Co-reporter:Yu-Zhong Wang;Ling Lin;Xiu-Li Wang;Gong-Peng Lin
Industrial & Engineering Chemistry Research February 4, 2015 Volume 54(Issue 4) pp:1282-1291
Publication Date(Web):Publication Date (Web): January 9, 2015
DOI:10.1021/ie504032w
Due to the limited toughening effect of BPM520 (a commercial acrylic-based core–shell structure impact modifier) on poly(butylene terephthalate) (PBT)/polycarbonate (PC) blends, magnesium oxide (MgO) was used as a transesterification catalyst, and BPM520 as a toughening agent to prepare PBT/PC blends by extrusion and injection molding. The structures and comprehensive properties of PBT/PC blends were investigated. Results of thermogravimetric analysis, Fourier transform infrared analysis, differential scanning calorimetry, and rheological measurements showed that transesterification reactions occurred among PBT, PC, and BPM520. As a result, the impact property of the blends was improved significantly, and only 5 wt % of BPM520 was needed to make the PBT/PC blend possess excellent toughness in the presence of MgO, which suggested a very efficient toughening approach for PBT/PC blends.
Co-reporter:Dan Shen, Ying-Jun Xu, Jia-Wei Long, Xiao-Hui Shi, Li Chen, Yu-Zhong Wang
Journal of Analytical and Applied Pyrolysis 2017 Volume 128(Volume 128) pp:
Publication Date(Web):1 November 2017
DOI:10.1016/j.jaap.2017.10.025
•Additive-type flame retardant for epoxy resin was conveniently prepared via neutralization between DOPA and melamine.•Flame retardance of the resulting material was significantly improved.•Pyrolysis behavior was comprehensively investigated by Py-GC/MS and TG-FTIR.•Flame retardant played the role of flame retardance in both condensed and gaseous phases.A melamine-organophosphinic acid salt (MDOP) was synthesized via neutralization of dibenzo[c,e][1,2]oxaphosphinic acid (DOPA) with melamine, and used as an additive-type flame retardant for epoxy resin (EP). Thermal stability and flame retardance was comprehensively evaluated via thermogravimetric analysis (TGA), UL-94 vertical burning test, limiting oxygen index (LOI) and cone calorimetry. The cured epoxy easily passed UL-94 V-0 rating with 0.33% content of P (5 phr MDOP); and LOI value of 38.0% was further achieved with 10 phr MDOP. The peak heat release (PHRR), total heat release (THR), total smoke production (TSP) and fire growth rate (FIGRA) were all reduced with the incorporation of MDOP. The pyrolysis behavior of the flame-retardant EP systems from Py-GC/MS and TG-FTIR suggested that MDOP played the role of flame retardance in both condensed and gaseous phases. Interestingly, the incorporation of MDOP did not deteriorate the mechanical properties of epoxy resin.
Co-reporter:Hai-Yi Zhong;Rong Yang;Zhi-Ying Meng;Xiao-Min Ding;Xiao-Feng Liu;Yu-Zhong Wang
Journal of Materials Chemistry C 2017 vol. 5(Issue 13) pp:3306-3314
Publication Date(Web):2017/03/30
DOI:10.1039/C6TC05493E
An azobenzene-containing thermotropic liquid crystalline polyester showing unique thermo- and photo-responsive behaviours was synthesized by polycondensation from mesogenic dial 4,4′-bis(6-hydroxyhexyloxy)azobenzene (BHHAB) with 2-phenylsuccinic acid (PSA), and named as poly(4,4′-bis(6-hydroxyhexyloxy)azobenzene phenylsuccinate) (PBHPS). Liquid crystalline behaviours were investigated through differential scanning calorimetry (DSC), polarizing optical microscopy (POM) and wide-angle X-ray diffraction (WAXD). PBHPS showed a smectic phase with strong π–π interactions between the adjacent phenyl rings or between the side group and mesogenic unit, which could be regarded as physical crosslinking points that made PBHPS have good shape memory and self-healing properties. A series of PBHPS/methylcellulose bilayer films were prepared to study the reversible photo-mechanical properties. UV-vis absorption spectra were used to study the reversible photo-responsive behaviour of the polyester, proving that the reversible photoisomerization-induced volume expansion of the PBHPS layer resulted in good reversible photo-responsive properties.
Co-reporter:Hai-Yi Zhong;Xiao-Feng Liu;Rong Yang;Yu-Zhong Wang
Journal of Materials Chemistry C 2017 vol. 5(Issue 37) pp:9702-9711
Publication Date(Web):2017/09/28
DOI:10.1039/C7TC02393F
Novel liquid crystalline copolyesters named as P(BH-co-BPn)PS, with azobenzene and biphenyl group mesogenic units, were designed and synthesized conveniently by one pot melt polycondensation. All P(BH-co-BPn)PS copolyesters showed good thermal stability, smectic liquid crystalline behavior with π–π interactions in the polymer chains. As the three different functional building blocks (azobenzene and biphenyl chromophores, liquid crystals, π–π interactions) work together, P(BH-co-BPn)PS were responsive to external stimuli at the molecular level, exhibiting thermal shape memory, photo-induced bending and self-healing behaviors at the macroscopic level. It was noteworthy that the different responsive properties of the photo-active azobenzene and photo-inert biphenyl mesogenic units made a great contribution in the photo responsive behavior of these copolyesters, resulting in reversible bending and unbending behaviors for P(BH-co-BP30)PS. In addition, without the chemical crosslink, these copolyesters could be reshaped and reprocessed. Taking advantage of the features, these copolyesters containing amphi-mesogenic units can help to facilitate numerous applications like soft actuators and smart materials.
Co-reporter:Xue Dong, Rong-Tao Duan, Yan-Peng Ni, Zhi-Jie Cao, Li Chen, Yu-Zhong Wang
Polymer Degradation and Stability 2017 Volume 146(Volume 146) pp:
Publication Date(Web):1 December 2017
DOI:10.1016/j.polymdegradstab.2017.09.022
•A series of imidized norbornene-containing PET copolyesters were successfully prepared.•Flame retardancy of the copolyesters was improved as a result of cross-linking between the imidized norbornene groups.•Cross-linking and rDA reaction happened at the same time, exhibiting a competitive relationship between each other.Retro-Diels-Alder reaction (rDA) has been widely used as a common modification approach for expanding functional applications of polymers. Especially, it has become an effective method of current cross-linking chemistry. With the goal of designing a cross-linkable PET-based copolyester toward flame retardancy and anti-dripping during combustion, dimethyl 5-(1,3-dioxo-3a,4,7,7a-tetrahydro-1H-4,7-methanoisoindol-2(3H)-yl) isophthalate (DMTMI) was incorporated as the functional co-monomer into PET chains via random transesterification polycondensation. Thermogravimetry-differential scanning calorimetry (TG-DSC) and rheological studies demonstrated the existence of cross-linking behavior at high temperature. By controlling the co-monomer content, expected flame retardancy was obtained, as illustrated by the results from the limiting oxygen index (LOI) and cone calorimetry. Furthermore, LOI values increased firstly and then decreased with the content of DMTMI increased, which was related to the existence of rDA reaction, and further proposed that a competitive relationship between the release of inflammable cyclopentadiene during rDA reaction and cross-linking behavior occurred in combustion. The hypothesis was verified through pyrolysis-gas chromatograph-mass spectrometry (Py-GC-MS).
Co-reporter:Xue-Bao Lin, Shuang-Lan Du, Jia-Wei Long, Li Chen, and Yu-Zhong Wang
ACS Applied Materials & Interfaces 2016 Volume 8(Issue 1) pp:881
Publication Date(Web):December 28, 2015
DOI:10.1021/acsami.5b10287
An organophosphorous hybrid (BM@Al-PPi) with unique core–shell structure was prepared through hybridization reaction between boehmite (BM) as the inorganic substrate and phenylphosphinic acid (PPiA) as the organic modifier. Fourier transform infrared spectra (FTIR), solid state 31P and 27Al magic angle spinning nuclear magnetic resonance, X–ray diffraction, and element analysis were used to investigate the chemical structure of the hybrids, where the microrod–like core was confirmed as Al-PPi aggregates generated from the reaction between BM and PPiA, and those irregular nanoparticles in the shell belonged to residual BM. Compared with the traditional dissolution–precipitation process, a novel analogous suspension reaction mode was proposed to explain the hybridization process and the resulting product. Scanning electronic microscopy further proved the core–shell structure of the hybrids. BM exhibited much higher initial decomposition temperature than that of Al-PPi; therefore, the hybrid showed better thermal stability than Al-PPi, and it met the processing temperature of semi–aromatic polyamide (HTN, for instance) as an additive-type flame retardant. Limiting oxygen index and cone calorimetric analysis suggested the excellent flame-retardant performance and smoke suppressing activity by adding the resulting hybrid into HTN.Keywords: boehmite; flame retardance; hybrid; phenylphosphinic acid; semiaromatic polyamide; thermal stability
Co-reporter:Yi Tan, Zhu-Bao Shao, Lei-Xiao Yu, Jia-Wei Long, Min Qi, Li Chen and Yu-Zhong Wang
Polymer Chemistry 2016 vol. 7(Issue 17) pp:3003-3012
Publication Date(Web):13 Apr 2016
DOI:10.1039/C6PY00434B
To obtain highly fire-safe epoxy resin (EP), piperazine-modified ammonium polyphosphate (PAz-APP) with multiple active –NH– groups was prepared and utilized as a highly effective flame-retardant hardener. After curing by PAz-APP as a monocomponent hardener, cross-linked networks containing both tertiary amino and ether linkages were obtained, which resulted in two glass transitions. Thanks to the phosphorus-containing inorganic part, PAz-APP brought excellent flame retardance and smoke suppression efficiency to the EP system. The cured sample passed V-0 rating (UL-94) with only 7.5 wt% addition of PAz-APP. Cone calorimetric results suggested that, compared with PAz/EP (as a reference sample), both the peak-heat release rate (PHRR) and total smoke production (TSP) of PAz-APP 15/EP (15 wt% addition) sharply dropped by 81.5% and 80.0%, respectively. By analyzing the chemical constitution of the decomposing residues at different temperatures, it was noticed that PAz-APP mainly acted as a flame retardant in the condensed phase via the formation of phosphorus-rich char. Dynamic mechanical analysis (DMA) illustrated that the main glass transition temperature (Tg) of PAz-APP 15/EP was as high as 162.4 °C. Furthermore, the incorporation of PAz-APP did not worsen the mechanical properties, but contrarily, improved the impact strength.
Co-reporter:Xue Dong, Li Chen, Rong-Tao Duan and Yu-Zhong Wang
Polymer Chemistry 2016 vol. 7(Issue 15) pp:2698-2708
Publication Date(Web):14 Mar 2016
DOI:10.1039/C6PY00183A
The concept of incorporating cross-linkable precursor as the copolymerizing monomer has been proved efficient for polyesters to achieve low flammability and anti-dripping property. Adapting this concept, in our latest paper, a new co-monomer named 5-(2,5-dioxo-3-phenyl-2,5-dihydro-1H-pyrrol-1-yl) isophthalic acid (DPDPI) was synthesized and incorporated into PET chain. Results from limiting oxygen index (LOI), UL-94 and the cone calorimetric test demonstrated that these PET-co-DPDPI copolyesters possess excellent flame retardance and anti-dripping performance. UL-94 V-0 rating could be achieved with a DPDPI content of as low as 10 mol% (PET-co-DPDPI10). Results from thermogravimetry-differential scanning calorimetry (TG-DSC) and dynamic oscillatory rheology proved the existence of the cross-linking behaviour during heat. The cross-linked polymer structures were stable at high temperature and could promote the char formation during burning. According to the results of Raman spectroscopy, X-ray photoelectron spectrometry (XPS) and pyrolysis/gas chromatography-mass spectrometry (Py/GC-MS), the cross-linking and flame-retardant mechanism were proposed for PET-co-DPDPIX, that during combustion, 2π + π cycloaddition which occurred between the phenylmaleimide groups as the cross-linking reaction. Afterward, the cross-linked networks promoted aromatization and carbonization, which resulted in self-extinguishing and anti-dripping.
Co-reporter:Yi Tan, Zhu-Bao Shao, Lei-Xiao Yu, Ying-Jun Xu, Wen-Hui Rao, Li Chen, Yu-Zhong Wang
Polymer Degradation and Stability 2016 Volume 131() pp:62-70
Publication Date(Web):September 2016
DOI:10.1016/j.polymdegradstab.2016.07.004
To expand the application of ammonium polyphosphate (APP) in epoxy resin (EP), hyperbranched polyethyleneimines (PEI) were selected to modify it via cation exchange reaction. Then, a highly-efficient flame-retardant hardener with poly-functionalities for EP was successfully prepared and named as PEI-APP. After curing, PEI-APP endowed the EP samples with good flame retardance and smoke suppression performance. Results suggested the total heat release (THR) and total smoke production (TSP) decreased 76.1% and 70.5% respectively. Thermogravimetric analyses (TGA) of the PEI-APP cured EPs displayed a slight improvement in the high temperature region compared with the reference sample (PEI/EP). Dynamic mechanical analysis (DMA) demonstrated that the glass transition temperature (Tg) of PEI-APP/EP also slightly increased compared with PEI/EP. Fourier transform infrared spectra (FTIR) was used to analyse the condensed products of PEI-APP/EP samples at different temperatures to investigate the flame-retardant mechanism. All the aforementioned results distinctly confirmed that PEI-APP did not only act as an effective flame-retardant hardener for EP, but also brought a good thermal stability and improved the smoke suppression to the system. This polyamine hardener provided a new platform for intumescent flame-retardant application in EP.
Co-reporter:Yi Tan, Zhu-Bao Shao, Xue-Fang Chen, Jia-Wei Long, Li Chen, and Yu-Zhong Wang
ACS Applied Materials & Interfaces 2015 Volume 7(Issue 32) pp:17919
Publication Date(Web):July 17, 2015
DOI:10.1021/acsami.5b04570
A novel multifunctional organic–inorganic hybrid was designed and prepared based on ammonium polyphosphate (APP) by cation exchange with diethylenetriamine (DETA), abbreviated as DETA-APP. Then DETA-APP was used as flame-retardant curing agent for epoxy resin (EP). Curing behavior, including the curing kinetic parameters, was investigated by differential scanning calorimetry (DSC) and X-ray photoelectron spectroscopy (XPS). The flame retardance and burning behavior of DETA-APP cured EP were also evaluated. The limiting oxygen index (LOI) value of DETA-APP/EP was enhanced to 30.5% with only 15 wt % of DETA-APP incorporated; and the UL-94 V-0 rating could be easily passed through with only 10 wt % of the hybrid. Compared with DETA/EP, the peak-heat release rate (PHRR), total heat release (THR), total smoke production (TSP), and peak-smoke production release (SPR) of DETA-APP/EP (15 wt % addition), obtained from cone calorimetry, were dropped by 68.3, 79.3, 79.0, and 30.0%, respectively, suggesting excellent flame-retardant and smoke suppression efficiency. The flame-retardant mechanism of DETA-APP/EP has been investigated comprehensively. The results of all the aforementioned studies distinctly confirmed that DETA-APP was an effective flame-retardant curing agent for EP.Keywords: ammonium polyphosphate; curing; epoxy resin; flame retardance; hybrid
Co-reporter:Ze-Yong Zhao, Liang-Ping Dong, Li Chen and Yu-Zhong Wang
RSC Advances 2015 vol. 5(Issue 23) pp:17967-17975
Publication Date(Web):02 Feb 2015
DOI:10.1039/C5RA00450K
The influence of a high loading of magnesium hydroxide (Mg(OH)2, MDH) on the morphology and properties of polypropylene (PP)/ethylene–octene copolymer (POE) blends has been investigated via scanning electron microscopy, dynamic mechanical thermal analysis and tensile mechanical testing. It was demonstrated that the mechanical properties, especially the elongation at break, are highly related to the phase structure exhibited by the composites. In the PP/POE 90/10 and 70/30 blends, the addition of a high loading of MDH lowered the average diameter of the dispersed POE domains, also the MDH and POE domains were separately dispersed in the PP matrix. Meanwhile, the elongation at break of the samples sharply declined to an unacceptable level. While in the PP/POE 50/50 blends, a co-continuous structure was formed and it could be maintained even after a large amount of MDH was added. The co-continuous structure was found to be a key factor for tolerating high loading of additives and retaining acceptable mechanical properties, especially the elongation at break.
Co-reporter:Bo-Wen Liu, Hai-Bo Zhao, Yi Tan, Li Chen, Yu-Zhong Wang
Polymer Degradation and Stability 2015 Volume 122() pp:66-76
Publication Date(Web):December 2015
DOI:10.1016/j.polymdegradstab.2015.10.009
Several kinds of novel flame-retardant-free and thermo-crosslinkable epoxy resins (EPs) containing azobenzene or/and phenylacetylene groups have been synthesized and characterized, and the flame retardant properties as a result of thermal crosslinking during combustion were investigated in detail. Crosslinking behaviors were tested by simultaneous thermogravimetry–differential scanning calorimetry (TGA–DSC). Thermal stabilities were investigated by thermogravimetric analysis (TGA). Flame retardance of the resulting EPs was evaluated through LOI tests, and combustion behaviors were studied via cone calorimetry and micro-combustion calorimetry (MCC), which further confirmed that flame retardance of these EPs was significantly improved, despite the absence of conventional flame retardant. Py–GC/MS analysis was used to investigate the degradation mechanism of these epoxy resins, and the results confirmed that the flame-retardant activity of epoxy resins mainly took effect in the condensed phase. The chemical constitution of the char layers were investigated by XPS and Raman spectrum. The co-crosslinking behavior between azobenzene and phenylacetylene groups was predicted and confirmed, which led to the most compact char layer, therefore resulted in the best flame retardance of these EPs.
Co-reporter:Rong Yang, Li Chen, Chao Ruan, Hai-Yi Zhong and Yu-Zhong Wang
Journal of Materials Chemistry A 2014 vol. 2(Issue 30) pp:6155-6164
Publication Date(Web):28 May 2014
DOI:10.1039/C4TC00512K
A series of main-chain thermotropic liquid crystalline polyesters were synthesized by polycondensation from mesogenic dial such as 4,4′-bis(6-hydroxyhexyloxy)biphenyl (BHHBP) and various diacids with different substituents such as succinic acid (no side group), 2-methylsuccinic acid (aliphatic side group) and 2-phenylsuccinic acid (aromatic side group), named poly(4,4′-bis(6-hydroxyhexyloxy)biphenyl succinate) (PBDS), poly(4,4′-bis(6-hydroxyhexyloxy)biphenyl methylsuccinate) (PBDMS), and poly(4,4′-bis(6-hydroxyhexyloxy)biphenyl phenylsuccinate) (PBDPS), respectively. Liquid crystalline behaviours were investigated through differential scanning calorimetry (DSC), polarizing optical microscopy (POM) and small angle X-ray scattering (SAXS) and the thermal stability of the polyesters was determined via thermogravimetric analysis (TGA). PBDS, PBDMS and PBDPS showed a SmF, SmB and SmA phase, respectively. On enlarging the side group, the d-spacing of the smectic layer increased, indicating folding packing of the polymer chains. Therefore, the adjacent phenyl rings in side groups stacked well together and formed strong π–π interactions even when the temperature was higher than Ti. The special structure of PBDPS could provide good mechanical properties. Thus, PBDPS exhibited the maximum tensile stress (28.6 MPa) and the highest elongation at break (1060%). Furthermore, the strong π–π interaction can act as netpoints; therefore, PBDPS exhibited excellent shape fixing (>99%) and shape recovery ratio (>99%) with large strain (>220%).
Co-reporter:Yi Zhang, Li Chen, Jing-Jing Zhao, Hong-Bing Chen, Ming-Xin He, Yan-Peng Ni, Jun-Qiu Zhai, Xiu-Li Wang and Yu-Zhong Wang
Polymer Chemistry 2014 vol. 5(Issue 6) pp:1982-1991
Publication Date(Web):15 Nov 2013
DOI:10.1039/C3PY01030A
In this study, a novel phosphorus-containing ionic monomer, named sodium salt of 10H-phenoxaphosphine-2,8-dicarboxylic acid,10-hydroxy-,2,8-dihydroxyethyl ester,10-oxide (DHPPO-Na), was synthesized, characterized, and then copolymerized to prepare poly(ethylene terephthalate)-based ionomers. The chemical structure of the resulting ionomers was confirmed by 1H, 13C, and 31P NMR spectroscopy. Thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) were used to investigate the thermal properties of the ionomers. Compared with that of neat PET, the initial decomposition temperature of PETIs decreased in a nitrogen atmosphere while it increased in air. The crystallinity of PETIs was enhanced firstly and then destroyed with the ionic group increase. The limiting oxygen index (LOI) test and cone calorimeter were used to characterize the flame-retardant properties of the ionomers. The results showed that the introduction of DHPPO-Na could endow an expected flame-retardant performance, meanwhile it considerably restricted the melt-dripping behavior and suppressed the smoke release. The rheology test confirmed that the ionic groups increased the melt viscosity via ionic aggregation during heating, which was a benefit for the flame-retardant property of the copolyester.
Co-reporter:Li Yu, Li Chen, Liang-Ping Dong, Liang-Jie Li and Yu-Zhong Wang
RSC Advances 2014 vol. 4(Issue 34) pp:17812-17821
Publication Date(Web):31 Mar 2014
DOI:10.1039/C4RA00700J
A novel organic–inorganic hybrid flame retardant (DOPA–ATH), which was prepared via reacting dibenzo[c,e][1,2]oxaphosphinic acid (DOPA) with aluminum trihydroxide (ATH), was incorporated in ethylene-vinyl acetate copolymer (EVA) to improve its flame retardance. The structure, morphology and thermal stability of the hybrid flame retardant were characterized by Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), and thermogravimetric analysis (TGA). The results suggested that DOPA was grafted onto ATH successfully, therefore resulting in higher thermostability than ATH. The flame retardance and burning behaviour of EVA with DOPA–ATH were also studied using limiting oxygen index (LOI), Underwriter laboratory 94 vertical burning test (UL-94 V) and cone calorimeter test (CCT). Results of UL-94 tests and LOI tests showed that the flame retardance of EVA/DOPA–ATH was better than EVA/ATH binary and EVA/DOPA/ATH ternary flame-retardant composites. The data obtained from the CCT showed that the peak heat release rate (PHRR) of EVA with the addition of 50 wt% DOPA–ATH was reduced by about 25% comparing with EVA with equivalent ATH. Total heat release (THR) and total smoke production (TSP) were reduced remarkably as well. The thermogravimetric analysis (TGA) data showed that the thermal stability of EVA/DOPA–ATH was improved with increased initial decomposition temperature and char residue. SEM observations of cryogenically fractured and tension fractured surfaces showed that EVA/DOPA–ATH had better interfacial interaction comparing with those of EVA/ATH and EVA/DOPA/ATH, which resulted in better elongation at break and tensile strength.
Co-reporter:Rong-Kun Jian, Li Chen, Bin Zhao, Yuan-Wei Yan, Xiao-Fan Li, and Yu-Zhong Wang
Industrial & Engineering Chemistry Research 2014 Volume 53(Issue 6) pp:2299-2307
Publication Date(Web):January 20, 2014
DOI:10.1021/ie403726m
Three metal hypophosphites, including aluminum hypophosphite (AP), magnesium hypophosphite (MP), and calcium hypophosphite (CP), were applied to flame retard acrylonitrile–butadiene–styrene (ABS). Thermal stability of three flame-retardant ABS were evaluated, and the enhancement of thermal stability were found. Flammable properties of flame-retardant ABS were investigated by Underwriters Laboratories 94 vertical burning test (UL-94), limit oxygen index (LOI), and cone calorimetry. Results suggested that AP could endow the best flame retardance for ABS with a UL-94 V-0 rating and LOI value of 25.1%. The peak heat release rate of ABS-AP reduced to 174.8 kW/m2, and the total heat released was decreased to 40.9 MJ/m2. Thermogravimetric Fourier transform infrared (TG-FTIR), FTIR, and scanning electron microcsopy–energy-dispersive X-ray spectrometry (SEM-EDX) were used to characterize the gaseous products and condensed residue respectively. Results showed that the flame-retardant mechanism was attributed to the formation of a two-layer protective barrier consisting of an organic P–O–C char layer and an inorganic layer to insulate material from fire and oxygen in the condensed phase, and the generation of P• and PO• to capture the reactive radicals in the vapor phase.
Co-reporter:Rong-Kun Jian, Li Chen, Si-Yang Chen, Jia-Wei Long, Yu-Zhong Wang
Polymer Degradation and Stability 2014 Volume 109() pp:184-193
Publication Date(Web):November 2014
DOI:10.1016/j.polymdegradstab.2014.07.018
Aluminum isobutylphosphinate (APBu) and its synergistic system with red phosphorus (APBu/RP) were used to flame-retard ABS. With the addition of APBu to ABS, the flame retardance of the material was greatly improved, that LOI value was as high as 29.8%, and a UL-94 V-0 rating was obtained; moreover, heat release parameters obtained from cone calorimetry decreased. However, the smoke release of the material during combustion increased. When RP was added to ABS-APBu system, flame-retardant synergism was gained, and it was helpful to reduce the smoke release of the material. The decomposition behaviors of materials were studied by thermogravimetric analysis (TG), and it was found that the residues of materials at 700 °C increased with the addition of APBu or APBu/RP. The flame-retardant mechanisms of APBu and APBu/RP were analyzed by Fourier transform infrared spectrum (FTIR), scanning electron microscopy (SEM) and pyrolysis-gas chromatograph/mass spectrometer (Py-GC/MS). Results suggested that the addition of RP to ABS-APBu further enhanced the flame retardation of APBu both in the gaseous phase and condensed phase, leading to a high synergistic effect.
Co-reporter:Hai-Bo Zhao, Bo-Wen Liu, Xiao-Lin Wang, Li Chen, Xiu-Li Wang, Yu-Zhong Wang
Polymer 2014 Volume 55(Issue 10) pp:2394-2403
Publication Date(Web):13 May 2014
DOI:10.1016/j.polymer.2014.03.044
Flame-retardant-free and thermo-cross-linkable copolyesters have been synthesized, and their flame retardation and anti-dripping behavior as a consequence of cross-linking during combustion were investigated in detail. TG-DSC simultaneous thermal analysis, rheological analysis, and TGA established the extent and rate of the cross-linking reaction. The extent of cross-linking depends on the content of cross-linkable monomer, PEPE, and the higher the extent of the cross-linking, the better the flame retardance and anti-dripping performance of copolyesters. The large melt viscosity caused by cross-linked networks at high temperature played the most important role in anti-dripping of copolyesters. TG-FTIR results confirmed that the flame-retardant activity of copolyesters mainly took effect in the condensed phase, and XPS results indicated that the carbonization process was aromatization-dominant. SEM and Raman analysis suggested that the char layers were constituted mainly of polyaromatic species with small and uniform microstructures at the surface. Consequently, both the large melt viscosity and the formation of an especially compact char with fine microstructure resulting from cross-linking were considered as the key to the flame retardance and anti-dripping performance of the polymer when subjected to the flame.
Co-reporter:Rong Yang, Li Chen, Rui Jin and Yu-Zhong Wang
Polymer Chemistry 2013 vol. 4(Issue 2) pp:329-336
Publication Date(Web):24 Aug 2012
DOI:10.1039/C2PY20579C
A series of phosphorus-containing main-chain thermotropic liquid crystalline copolyesters named poly(4,4′-biphenylene decanedioate-co-4,4′-(phenylphosphoryl)dibenzoate) (PBPDP) were synthesized by random polycondensation from mesogenic diol 4,4′-biphenol (BP), decanedioic acid (DA) and phosphorus-containing non-coplanar diacid named 4,4′-(phenylphosphoryl)dibenzoic acid (PPDBA). Chemical structures and physical properties of PBPDPs were characterized by Fourier-transform infrared spectroscopy (FTIR), proton and 31P nuclear magnetic resonance (NMR), differential scanning calorimetry (DSC) and X-ray diffraction (WAXD). Thermal stability of the copolyesters was determined via thermogravimetric analysis (TGA), and the liquid crystalline behaviours were observed using polarizing optical microscopy (POM). Results showed that the introduction of PPDBA into the copolyester could decrease the liquid crystalline temperature (Tlc) and the isotropic temperature (Ti) as a result of both copolymerization and the non-coplanar structure of PPDBA; furthermore, when the molar ratio of PPDBA reached 15%, the copolyester turned into a semi-crystalline polymer and lost its liquid crystallinity. Thermal stability of the copolyester increased with increasing the content of PPDBA, due to the positive contribution of the phosphorus-containing structure.
Co-reporter:Hong-Bing Chen, Xue Dong, David A. Schiraldi, Li Chen, De-Yi Wang, Yu-Zhong Wang
Journal of Analytical and Applied Pyrolysis 2013 Volume 99() pp:40-48
Publication Date(Web):January 2013
DOI:10.1016/j.jaap.2012.11.003
A novel phosphorus-containing poly(trimethylene terephthalate) (PTT) derived from 2-(6-oxido-6H-dibenz〈c,e〉〈1,2〉oxaphosphorin-6-yl)-1,4-hydroxyethoxy phenylene was synthesized via solid state polymerization, and its chemical structure was confirmed with 1H NMR. The thermal stability of the resulting copolyester was analyzed by thermogravimetric analysis. With the introduction of phosphorus-containing segments, polyester onset weight-loss temperatures in both nitrogen and air are enhanced. Thermal degradation kinetics were analyzed using the Flynn–Wall–Ozawa method, which showed a decreased activation energy for the copolyester compared with that for neat PTT, strongly suggesting that the increased onset weight-loss temperature in nitrogen is a result of enhanced carbonization. Microscale combustion calorimetry was carried out to test the flammability behavior of the copolyester; improved flame-retardant properties were observed with incorporated phosphorus components. Py-GC–MS testing revealed that the pyrolysis of phosphorus-containing copolyester is not significantly affected by the phosphorus incorporation.Highlights► P-containing monomer was incorporated into poly(trimethylene terephthalate) (PTT) via solid state polymerization. ► Onset weight-loss temperatures of the P-containing PTT copolyester in both nitrogen and air were enhanced. ► The activation energy for the copolyester in nitrogen was decreased compared with that for neat PTT. ► Improved flame-retardant properties tested by microscale combustion calorimetry were observed with incorporated phosphorus components. ► Py-GC–MS testing revealed that the pyrolysis of the P-containing copolyester is not significantly affected.
Co-reporter:Hong-Bing Chen, Jian-Bing Zeng, Xue Dong, Li Chen and Yu-Zhong Wang
CrystEngComm 2013 vol. 15(Issue 14) pp:2688-2698
Publication Date(Web):24 Jan 2013
DOI:10.1039/C3CE26631A
The crystallization behavior of neat PTT and phosphorus-containing PTT copolyester with specific block chain structure (PTTDs, obtained by solid-state polymerization (SSP)) has been investigated by differential scanning calorimetry (DSC), polarized microscopy (POM) and wide-angle X-ray diffraction (WAXD). The overall crystallization kinetics study shows that crystallization is retarded with introduction of a phosphorus-containing segment. This retardation effect is obvious for PTTD10; however, no greater retardation can be observed with further increasing the phosphorus content, which is attributed to the hindering effect of phosphorus-containing segment and specific chain structure, and is in accordance with the crystallization morphology. The crystallization rate of PTTDs is much lower at high crystallization temperature than that of PTT, which can be explained by the diluent effect of the non-crystallizable chain segment. The result of spherulite growth is in accordance with DSC study. The rigid amorphous fraction (RAF) is also calculated, which increases with increasing phosphorus content, suggesting that RAF is not the main factor for retarded crystallization. The main factors of retarded crystallization are probably caused by the diluent effect and the hindering effect of the specific chain structure. With incorporation of phosphorus-containing segments, the transition temperature is slightly changed; however, the equilibrium melting temperature (Tm0) of the copolyester decreases. The phosphorus-containing segment plays the role of nucleation agent at regime III.
Co-reporter:Gong-Peng Lin, Li Chen, Xiu-Li Wang, Rong-Kun Jian, Bin Zhao, and Yu-Zhong Wang
Industrial & Engineering Chemistry Research 2013 Volume 52(Issue 44) pp:15613-15620
Publication Date(Web):2017-2-22
DOI:10.1021/ie402396x
In this manuscript, synergistic effect was found when aluminum hydroxymethylphosphinate (AHMP) and melamine pyrophosphate (MPyP) with a suitable mass ratio were used together for glass-fiber-reinforced polyamide 6 composites (GFPA6). Both vertical burning test (UL-94) and limited oxygen index (LOI) results showed that GFPA6 containing 5 wt % AHMP and 25 wt % MPyP had excellent flame retardance, i.e. its LOI value was 31.0 and UL-94 reached V-0 rating even for the sample with 1.6 mm thickness. Besides, the flammable properties and smoke suppression of GFPA6 were also improved demonstrated by cone calorimetry results. The thermal stability and the decomposition activation energies (Eα) were studied by TGA. Moreover, the morphology of char after the LOI test was investigated by SEM. It was found that the interaction existing between PA6, AHMP, and MPyP resulted in the higher char content and stable char layer on the GFPA6 surface, which is helpful in improving the flame retardancy of GFPA6.
Co-reporter:Bin Zhao, Li Chen, Jia-Wei Long, Hong-Bing Chen, and Yu-Zhong Wang
Industrial & Engineering Chemistry Research 2013 Volume 52(Issue 8) pp:2875
Publication Date(Web):February 5, 2013
DOI:10.1021/ie303446s
Aluminum hypophosphite (AP) and aluminum isobutylphosphinate (APBu) were used to flame retard polyamide 6 (PA6). Addition of either AP or APBu resulted in an increased LOI value, UL-94 V-0 rating, and decreased heat release in cone calorimetric tests. However, different chemical structures of two flame retardants caused different flame-retardant effects: APBu endowed PA6 a higher LOI value and better UL-94 result than did AP. Decomposition pathways of AP, APBu, and the corresponding composites were investigated using TGA, TG-IR, Py-GC/MS, and FTIR characterization of the residues. The introduction of AP changed the thermal stability and decomposition behavior of the composites due to the cross-linking reactions occurred, which were proved by rheological analysis and TG-DSC. APBu could not essentially affect the composition of pyrolysis products and decomposition behaviors, but mainly produced phosphorus-containing free radical scavengers in the gaseous phase, which were positive to flame retardation. Finally, the proposed flame-retardant mechanisms of such systems were summarized.
Co-reporter:Zhen-Qi Shen, Li Chen, Ling Lin, Cheng-Liang Deng, Jing Zhao, and Yu-Zhong Wang
Industrial & Engineering Chemistry Research 2013 Volume 52(Issue 25) pp:8454
Publication Date(Web):June 5, 2013
DOI:10.1021/ie4010546
In this work, flame-retardant ethylene–propylene–diene terpolymer (EPDM) composites were prepared by incorporating intumescent flame-retardant (IFR) together with two different organically modified layered nanoparticles: montmorillonite (OMMT) and layered double hydroxides (OLDH). The morphology, fire behavior, thermal stability, flame-retardant synergism, and mechanical properties of the flame-retardant EPDM nanocomposites were studied. The introduction of a certain amount of OMMT (or OLDH) in the intumescent flame-retardant EPDM led to the considerable enhancement of flame retardance, thermal stability, and mechanical properties. Especially, the EPDM-IFR30-OLDH2 composite (100 phr EPDM, 30 phr IFR, and 2 phr OLDH) presented the highest tensile strength and could pass a UL-94 test V-0 rating; while the EPDM-IFR30-OMMT2 composite (100 phr EPDM, 30 phr IFR, and 2 phr OMMT) showed the lowest peak heat release rate (pHRR) and total heat release (THR) values. Different flame-retardant performances should be attributed to their own characteristics, dispersion state in EPDM matrix, and the change of structure during burning. The flame-retardant mechanisms for the composites were proposed to be condensed phase activity.
Co-reporter:Bin Zhao, Li Chen, Jia-Wei Long, Rong-Kun Jian, and Yu-Zhong Wang
Industrial & Engineering Chemistry Research 2013 Volume 52(Issue 48) pp:17162
Publication Date(Web):November 5, 2013
DOI:10.1021/ie4009056
A novel binary flame-retardant system was formed by introducing aluminum hypophosphite (AP) and aluminum isobutylphosphinate (APBu) together for PA6. The optimum flame retardant formulation was 1:1 (AP:APBu, 15 wt % in total), and the resulting flame-retardant PA6 could achieve a LOI value of 28.3 vol % and UL-94 V-0 rating. Cone calorimeter testing showed the samples containing binary flame retardants became less flammable with lower peak heat release rate (PHRR, 259 kW/m2). Dynamic oscillatory rheology and simultaneous thermogravimetry–differential scanning calorimetry results proved that cross-linking reactions existed in the samples containing AP. Morphology of the char layers was analyzed via SEM and laser Raman spectroscopy, and the results demonstrated the samples containing both AP and APBu formed more effective char. These results revealed that flame-retardant synergism existed between AP and APBu when they were combined to flame retard PA6. Consequently, a brief synergistic mechanism in this system was proposed.
Co-reporter:Hai-Bo Zhao, Li Chen, Jun-Chi Yang, Xin-Guo Ge and Yu-Zhong Wang
Journal of Materials Chemistry A 2012 vol. 22(Issue 37) pp:19849-19857
Publication Date(Web):08 Aug 2012
DOI:10.1039/C2JM34376B
In this manuscript, contradiction between the non-flammability and non-dripping of polyesters could be solved by copolymerizing terephthalic acid and ethylene glycol together with a pendent phenylethynyl-based monomer named 4-(phenylethynyl) di(ethylene glycol) phthalate (PEPE), which exhibited a cross-linkable nature at a proper temperature. TG-DSC simultaneous thermal analysis, FTIR, dissolution tests and rheological investigations proved the thermal cross-linking behavior of the copolyester, which was not active at the temperature of polymerization and processing but could cross-link rapidly at higher temperature before burning. LOI tests, cone calorimetry and small-scale flame tests further confirmed the self-extinguishment and inhibition for melt-dripping could be achieved through the cross-linking during burning, despite the absence of any flame-retardant element (say, bromine, chlorine, phosphorus, or nitrogen, etc.). Rheological analyses and the SEM microphotographs of the char showed P(ET-co-P)s exhibited a greater complex viscosity through the cross-linking at high temperature, leading to compact char residue, flame-retardant and anti-dripping effects.
Co-reporter:Li Chen, Yuan Luo, Zhi Hu, Gong-Peng Lin, Bin Zhao, Yu-Zhong Wang
Polymer Degradation and Stability 2012 Volume 97(Issue 2) pp:158-165
Publication Date(Web):February 2012
DOI:10.1016/j.polymdegradstab.2011.11.003
Compared with poly(butylene terephthalate) (PBT), glass-fibre-reinforced poly(butylene terephthalate) (GF-PBT) is difficult to flame retard with halogen-free flame retardants. In the present study, the aluminium salt of hypophosphorous acid (AP) was used as a flame retardant for GF-PBT. A series of flame-retardant GF-PBT composites was prepared via melt compounding. The flame retardance and combustion behaviour of the composites were studied by limiting oxygen index (LOI), vertical burning test (UL-94) and cone calorimetric test. Thermal behaviours and thermal decomposition kinetics were investigated by thermogravimetric analysis (TGA) under N2 atmosphere. The addition of AP to the composites could result in an increased LOI value, a UL-94 V-0 (1.6 mm) classification and a better fire performance in cone calorimetric tests. The char morphology observation after flame-retardant tests, calculation of decomposition kinetics, X-ray photoelectron spectroscopy (XPS) and infra-red spectral analysis of the char residue confirmed the condensed-phase flame-retardant mechanism. Furthermore, the mechanical properties of the flame-retardant composites were not deteriorated, retaining an acceptable level.
Co-reporter:Yuan-Wei Yan, Li Chen, Rong-Kun Jian, Shuang Kong, Yu-Zhong Wang
Polymer Degradation and Stability 2012 Volume 97(Issue 8) pp:1423-1431
Publication Date(Web):August 2012
DOI:10.1016/j.polymdegradstab.2012.05.013
An intumescent flame-retardant (IFR) system, which was comprised of a novel carbonization agent (CA) and ammonium polyphosphate (APP), was prepared for general purpose polystyrene. Thermal degradation and flame retardance of the PS/IFR composites were studied. The results of LOI and UL-94 test showed that when the content of APP and CA was 22.5 and 7.5 wt%, respectively, the LOI value of PS/IFR composite was 32.5%, and a V-0 classification could be achieved. The TGA data indicated that there was a synergistic effect between CA and APP. The cone calorimeter data showed that the heat release rate (HRR), the total heat release (THR) and the mass loss rate (MLR) were reduced largely with the addition of IFR. Some cone calorimeter data, such as smoke production rate (SPR), total smoke production (TSP) and carbon monoxide production (COP), revealed that the IFR could greatly suppress the generation of the smoke during the material flaming. The study on the flame-retardant mechanism of IFR indicated that a steady structure containing P–O–C was formed due to the reaction between APP and CA. The mechanical properties of PS and PS/APP/CA3:1 were also investigated, and the results showed that, compared to those of the neat PS, the tensile strength and the flexural strength of the PS/IFR composite decreased to a certain extent.
Co-reporter:Rong-Kun Jian;Zhi Hu ;Yu-Zhong Wang
Journal of Applied Polymer Science 2012 Volume 123( Issue 5) pp:2867-2874
Publication Date(Web):
DOI:10.1002/app.34845
Abstract
Red phosphorus encapsulated by polysiloxane (MRP) was prepared, and the chemical structure and morphology of MRP were characterized by FTIR and TEM, respectively. A series of flame retardant polycarbonate/acrylonitrile-butadiene-styrene containing MRP (PC/ABS/MRP) were prepared via melt-blending. The flame retardance of PC/ABS/MRP was investigated by limiting oxygen index (LOI) and UL-94 test. It was shown that the LOI value was increased to 27.7 and UL-94 achieved a V-0 rating at a 15 wt % loading of MRP. Cone calorimetric results showed that the peak of heat release rate (PHRR) of PC/ABS/15% MRP decreased from 452.7 to 198.0 kW/m2, and the total heat release decreased from 92.9 to 60.7 MJ/m2 compared with virgin PC/ABS. Thermal stability analysis showed that the char yield of the PC/ABS/15% MRP increased from 0 to 16.1 wt % under air atmosphere, and from 15.2 to 27.4 wt % under nitrogen atmosphere compared to virgin PC/ABS, respectively. The sample PC/ABS/15% MRP also showed excellent water resistance of flame retardance in 70°C water for 168 h. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Co-reporter:Hong-Bing Chen;Yi Zhang;Wei Wang;Bin Zhao ;Yu-Zhong Wang
Polymers for Advanced Technologies 2012 Volume 23( Issue 9) pp:1276-1282
Publication Date(Web):
DOI:10.1002/pat.2042
In order to improve the flame retardancy of the semi-biobased polyester, poly(trimethylene terephthalate) (PTT), bis-4-carboxyphenyl phenyl phosphine oxide (BCPPO) was used as a third monomer to synthesize a novel main-chain phosphorus-containing copolyester, poly(trimethylene terephthalate-co-BCPPO)s (PTTBP), through melt polycondensation. Phosphorus analysis of the resulting polymers suggests that BCPPO has been introduced to PTT chain successfully. 1H and 31P nuclear magnetic resonance spectra further confirm the random chemical structure. The thermal behavior was investigated by differential scanning calorimetry and thermogravimetric analysis. The introduction of BCPPO to PTT lowered the melting point and crystallization ability because of the random copolymerization and the rigid structure of BCPPO, and the thermal stabilities of PTTBP were improved in air but decreased in nitrogen. Rheological investigations showed that the complex viscosities of all the samples were independent of frequency at low frequency (say lower than 100 rads), and shear thinning effect occurred at higher frequency. The cone calorimeter was used to test the fire behavior of PTTBP, and the results suggested that the novel copolyester had good flame retardance. Copyright © 2011 John Wiley & Sons, Ltd.
Co-reporter:Wei-cheng Xiong 陈力;Bin Zhao;De-yi Wang
Chinese Journal of Polymer Science 2012 Volume 30( Issue 2) pp:297-307
Publication Date(Web):2012 March
DOI:10.1007/s10118-012-1126-2
A novel encapsulated flame retardant containing phosphorus-nitrogen (MSMM-Al-P) was prepared by encapsulating with polyamide 66 (PA66-MSMM-Al-P) for the flame retardation of polyamide 6 (PA6). The structure and thermal properties of PA66-MSMM-Al-P were characterized by Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy and thermogravimetric analysis. The flammability of PA6 containing flame retardants (MSMMAl-P and PA66-MSMM-Al-P) was investigated by the limiting oxygen index test, vertical burning test and cone calorimeter. The flame retardancy and cone calorimetric analyses suggested a synergistic effect between PA66 and MSMM-Al-P in the flame-retardant PA6. Thermal stability of the flame-retardant PA6 was also investigated.
Co-reporter:Wei-cheng Xiong 陈力;De-yi Wang;Fei Song
Chinese Journal of Polymer Science 2012 Volume 30( Issue 1) pp:72-81
Publication Date(Web):2012 January
DOI:10.1007/s10118-012-1100-z
The synergistic effect of phosphorus oxynitride (PON) with a novolac-based char former modified by salification (NA-metal salt) on the flame retardance of polyamide 6 (PA6) was investigated. For this purpose, various flame-retardant PA6 systems were melt-compounded with PON, PON/NA, PON/NA-V2O5 and PON/NA-Fe2O3, and their flame retardance was evaluated by measuring the limiting oxygen index (LOI) values and UL-94 vertical burning ratings. The results showed that, compared with the PA6/PON/NA system, the combination of two char formers (NA-V2O5, NA-Fe2O3) with PON could obviously improve the char formation and flame retardance of PA6. The flame retardance and cone calorimetric analyses showed the stronger synergism as well as the better flame retardant performance of PON/NA-Fe2O3 flame retardant system. The effects of different char formers on the flame retardance and thermal stability of this system were also discussed.
Co-reporter:Hong-Bing Chen, Li Chen, Xue Dong, Liang-Jie Li, Yu-Zhong Wang
Polymer 2012 Volume 53(Issue 16) pp:3520-3528
Publication Date(Web):19 July 2012
DOI:10.1016/j.polymer.2012.05.050
Phosphorus-containing flame-retardant monomer entitled 9,10-dihydro-10-[2,3-di(hydroxycarbonyl)propyl]-10-phospha-phenanthrene-10-oxide (DDP) was first esterified with 1,3-propane diol, then incorporated in poly(trimethylene terephthalate) (PTT) chain via solid-state polymerization (SSP) at 200 °C. Reaction kinetics of incorporation was studied choosing 30 wt% DDP content as representative example. The reaction rate constant kf was calculated to be 1.68 h−1. The intrinsic viscosity increased with the increase of tssp, and decreased with the increase of DDP content. The sequence distribution of resulted copolyester was also analyzed with 1H NMR. Results suggested that all of the samples possess block chemical structure, and the degree of randomness increased with the increase of transesterification. For the transesterification reaction occurs only in amorphous phase of the material, the copolyester exhibited greater tendency to form block constitution when increasing DDP content. DSC investigation further confirmed the non-random constitution of the resulted copolyester.
Co-reporter:Hong-Bing Chen, Li Chen, Yi Zhang, Jing-Jing Zhang and Yu-Zhong Wang
Physical Chemistry Chemical Physics 2011 vol. 13(Issue 23) pp:11067-11075
Publication Date(Web):12 May 2011
DOI:10.1039/C0CP02176H
A novel phosphorus-containing copolyester (PTTP), poly(trimethylene terephthalate) (PTT) copolyester with a bulky linking pendent group of 9,10-dihydro-10-[2,3-di(hydroxycarbonyl) propyl]-10-phosphaphenanthrene-10-oxide (DDP) was prepared, and its crystallization, crystal morphology and interference color were investigated in this article for the first time. Differential scanning calorimeter (DSC) results showed that with the increase of DDP content, the melting point (Tm) and crystallization ability of PTTP decreased. WAXD results suggests that the three samples share one crystal structure, however the crystallinity decreases with increasing DDP content. Polarized optical microscope (POM) observation indicated that the samples showed non-banded spherulites at a lower and higher temperature, and banded spherulites at the middle temperature range. From the micrographs obtained from scanning electronic microscopy (SEM) and atomic force microscopy (AFM), ringed patterns with many defects could be found for samples with higher DDP contents, which crystallized at a lower temperature, and a transformation from square-shaped spherulites to circular spherulites was noted for samples with higher DDP contents, which crystallized at a higher temperature. The interference color of the spherulites was also studied and it was shown that with the increase of film thickness or decrease of DDP content, the spherulites became more colorful under POM observation, indicating that the hindering effect and randomness caused by incorporating the DDP monomer with a bulky pendent group into the PTT molecular chain exhibited a negative influence on the molecular mobility and crystallization ability of the copolyester, and led to the formation of the defective band morphology and the less colorful interference color of the PTTP spherulites.
Co-reporter:Zhi Hu, Li Chen, Gong-Peng Lin, Yuan Luo, Yu-Zhong Wang
Polymer Degradation and Stability 2011 Volume 96(Issue 9) pp:1538-1545
Publication Date(Web):September 2011
DOI:10.1016/j.polymdegradstab.2011.03.010
Aluminum salts of phosphinic acid mixture of diisobutylphosphinic acid and monoisobutylphosphinic acid (HPA-2TBA-Al) and glass fibres were compounded with polyamide 6 to prepare a series of flame retardant GF/PA6 composites via melt blending. The flame retardance and burning behaviors of the composites were investigated by limiting oxygen index (LOI), vertical burning test (UL-94), and Cone calorimeter test. The thermal properties and decomposition kinetics were investigated by thermogravimetric analysis (TGA) under N2 atmosphere. Addition of HPA-2TBA-Al results in an increased LOI value, a UL-94 V-0 rating together with a decrease in both the values of PHRR and THR in Cone calorimetric analysis. Visual observations and scanning electronic microscopy (SEM) after flame retardant tests confirmed the char-formation which acts as a fire barrier in condense phase. Analysis of cone calorimeter data indicates that gas phase flame retardant mechanism exists in the GFPA6/HPA-2TBA-Al system.
Co-reporter:Zhi Hu;Gong-Peng Lin;Yu-Zhong Wang
Polymers for Advanced Technologies 2011 Volume 22( Issue 7) pp:1166-1173
Publication Date(Web):
DOI:10.1002/pat.1922
The aluminum phenylphosphinate (BPA-Al) was synthesized and its chemical structure was confirmed by FT-IR, 1H NMR, and inductively coupled plasma-atomic emission spectrometry (ICP-AES). BPA-Al was used to prepare a series of flame-retardant glass-fiber-reinforced polyamide 6 (GFPA6) composites together with melamine pyrophosphate (MPyP) and sodium tungstate (ST) via melt compounding. The flame retardancy of the composites was investigated by vertical burning test and cone calorimeter test. The thermal behaviors and decomposition kinetics were investigated by thermogravimetric analysis (TGA). BPA-Al alone could not improve the flame retardancy of GFPA6 composites, but the combination of BPA-Al and MPyP resulted in a UL-94 V-2 rating, and the addition of a small amount of ST to the flame retardant system could endow the composites a V-0 rating. The flame retardant systems also resulted in a decrease in PHRR and THR in cone calorimeter test. The analysis of thermal decomposition kinetics showed that the activation energies (Eα) of the flame-retardant composites dramatically decreased compared with that of GFPA6. Copyright © 2011 John Wiley & Sons, Ltd.
Co-reporter:Rong Yang, Li Chen, Wen-Qiang Zhang, Hong-Bing Chen, Yu-Zhong Wang
Polymer 2011 Volume 52(Issue 18) pp:4150-4157
Publication Date(Web):18 August 2011
DOI:10.1016/j.polymer.2011.06.047
Polycarbonate (PC) was blended with various loadings of novel phosphorus-containing thermotropic liquid crystalline copolyester named PHDDT to form the in situ reinforced composites (PC/PHDDT) by flake extrusion. The morphology, thermal behaviors, tensile properties and flame-retardant performances of PC/PHDDT composites were investigated. Results suggested that fine deformation and microfibrillation of PHDDT in PC matrix could be formed during flake extrusion, which was confirmed by both the SEM observation and rheological analysis. With the increase of PHDDT content, the limiting oxygen index (LOI), tensile strength and storage modulus of the composites were enhanced simultaneously, along with the gradually decreased values of the peak heat release rate (PHRR) and the total heat released (THR), indicating the in situ reinforced and flame-retardant PC/PHDDT composites could be obtained.
Co-reporter:Hong-Bing Chen, Yi Zhang, Li Chen, Zhu-Bao Shao, Ya Liu and Yu-Zhong Wang
Industrial & Engineering Chemistry Research 2010 Volume 49(Issue 15) pp:7052-7059
Publication Date(Web):July 2, 2010
DOI:10.1021/ie1006917
A novel phosphorus-containing copolyester, poly(trimethylene terephthalate)-co-poly(trimethylene DDP)s (PTTP), was synthesized through esterification and polycondensation of terephthalic acid (TPA), 1,3-propane diol (PDO), and 9,10-dihydro-10-[2,3-di(hydroxycarbonyl)propyl]-10-phospha-phenanthrene-10-oxide (DDP). The analysis of phosphorus content and the test of intrinsic viscosity indicated that DDP was successfully introduced to the poly(trimethylene terephthalate) (PTT) chain. The chemical structure of the resulting copolyesters was further confirmed by 1H NMR and 31P NMR. The thermal behaviors were investigated by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA), and it was shown that the introduction of DDP lowered the melting temperature and crystallization because of its bulky pendent groups and decreased the initial decomposition temperature in the nitrogen atmosphere due to its weak P−C bond. The flame retardant properties of the resulting copolyesters were characterized by limiting oxygen index (LOI) and cone calorimeter, and it was shown that the copolyesters had good inherent flame retardancy.
Co-reporter:Zhi-Ying Meng, Li Chen, Hai-Yi Zhong, Rong Yang, Xiao-Feng Liu, Yu-Zhong Wang
Composites Science and Technology (18 January 2017) Volume 138() pp:8-14
Publication Date(Web):18 January 2017
DOI:10.1016/j.compscitech.2016.11.006
Co-reporter:Hong-Bing Chen, Li Chen, Yi Zhang, Jing-Jing Zhang and Yu-Zhong Wang
Physical Chemistry Chemical Physics 2011 - vol. 13(Issue 23) pp:NaN11075-11075
Publication Date(Web):2011/05/12
DOI:10.1039/C0CP02176H
A novel phosphorus-containing copolyester (PTTP), poly(trimethylene terephthalate) (PTT) copolyester with a bulky linking pendent group of 9,10-dihydro-10-[2,3-di(hydroxycarbonyl) propyl]-10-phosphaphenanthrene-10-oxide (DDP) was prepared, and its crystallization, crystal morphology and interference color were investigated in this article for the first time. Differential scanning calorimeter (DSC) results showed that with the increase of DDP content, the melting point (Tm) and crystallization ability of PTTP decreased. WAXD results suggests that the three samples share one crystal structure, however the crystallinity decreases with increasing DDP content. Polarized optical microscope (POM) observation indicated that the samples showed non-banded spherulites at a lower and higher temperature, and banded spherulites at the middle temperature range. From the micrographs obtained from scanning electronic microscopy (SEM) and atomic force microscopy (AFM), ringed patterns with many defects could be found for samples with higher DDP contents, which crystallized at a lower temperature, and a transformation from square-shaped spherulites to circular spherulites was noted for samples with higher DDP contents, which crystallized at a higher temperature. The interference color of the spherulites was also studied and it was shown that with the increase of film thickness or decrease of DDP content, the spherulites became more colorful under POM observation, indicating that the hindering effect and randomness caused by incorporating the DDP monomer with a bulky pendent group into the PTT molecular chain exhibited a negative influence on the molecular mobility and crystallization ability of the copolyester, and led to the formation of the defective band morphology and the less colorful interference color of the PTTP spherulites.
Co-reporter:Hai-Yi Zhong, Li Chen, Rong Yang, Zhi-Ying Meng, Xiao-Min Ding, Xiao-Feng Liu and Yu-Zhong Wang
Journal of Materials Chemistry A 2017 - vol. 5(Issue 13) pp:NaN3314-3314
Publication Date(Web):2017/03/15
DOI:10.1039/C6TC05493E
An azobenzene-containing thermotropic liquid crystalline polyester showing unique thermo- and photo-responsive behaviours was synthesized by polycondensation from mesogenic dial 4,4′-bis(6-hydroxyhexyloxy)azobenzene (BHHAB) with 2-phenylsuccinic acid (PSA), and named as poly(4,4′-bis(6-hydroxyhexyloxy)azobenzene phenylsuccinate) (PBHPS). Liquid crystalline behaviours were investigated through differential scanning calorimetry (DSC), polarizing optical microscopy (POM) and wide-angle X-ray diffraction (WAXD). PBHPS showed a smectic phase with strong π–π interactions between the adjacent phenyl rings or between the side group and mesogenic unit, which could be regarded as physical crosslinking points that made PBHPS have good shape memory and self-healing properties. A series of PBHPS/methylcellulose bilayer films were prepared to study the reversible photo-mechanical properties. UV-vis absorption spectra were used to study the reversible photo-responsive behaviour of the polyester, proving that the reversible photoisomerization-induced volume expansion of the PBHPS layer resulted in good reversible photo-responsive properties.
Co-reporter:Hai-Bo Zhao, Li Chen, Jun-Chi Yang, Xin-Guo Ge and Yu-Zhong Wang
Journal of Materials Chemistry A 2012 - vol. 22(Issue 37) pp:NaN19857-19857
Publication Date(Web):2012/08/08
DOI:10.1039/C2JM34376B
In this manuscript, contradiction between the non-flammability and non-dripping of polyesters could be solved by copolymerizing terephthalic acid and ethylene glycol together with a pendent phenylethynyl-based monomer named 4-(phenylethynyl) di(ethylene glycol) phthalate (PEPE), which exhibited a cross-linkable nature at a proper temperature. TG-DSC simultaneous thermal analysis, FTIR, dissolution tests and rheological investigations proved the thermal cross-linking behavior of the copolyester, which was not active at the temperature of polymerization and processing but could cross-link rapidly at higher temperature before burning. LOI tests, cone calorimetry and small-scale flame tests further confirmed the self-extinguishment and inhibition for melt-dripping could be achieved through the cross-linking during burning, despite the absence of any flame-retardant element (say, bromine, chlorine, phosphorus, or nitrogen, etc.). Rheological analyses and the SEM microphotographs of the char showed P(ET-co-P)s exhibited a greater complex viscosity through the cross-linking at high temperature, leading to compact char residue, flame-retardant and anti-dripping effects.
Co-reporter:Rong Yang, Li Chen, Chao Ruan, Hai-Yi Zhong and Yu-Zhong Wang
Journal of Materials Chemistry A 2014 - vol. 2(Issue 30) pp:NaN6164-6164
Publication Date(Web):2014/05/28
DOI:10.1039/C4TC00512K
A series of main-chain thermotropic liquid crystalline polyesters were synthesized by polycondensation from mesogenic dial such as 4,4′-bis(6-hydroxyhexyloxy)biphenyl (BHHBP) and various diacids with different substituents such as succinic acid (no side group), 2-methylsuccinic acid (aliphatic side group) and 2-phenylsuccinic acid (aromatic side group), named poly(4,4′-bis(6-hydroxyhexyloxy)biphenyl succinate) (PBDS), poly(4,4′-bis(6-hydroxyhexyloxy)biphenyl methylsuccinate) (PBDMS), and poly(4,4′-bis(6-hydroxyhexyloxy)biphenyl phenylsuccinate) (PBDPS), respectively. Liquid crystalline behaviours were investigated through differential scanning calorimetry (DSC), polarizing optical microscopy (POM) and small angle X-ray scattering (SAXS) and the thermal stability of the polyesters was determined via thermogravimetric analysis (TGA). PBDS, PBDMS and PBDPS showed a SmF, SmB and SmA phase, respectively. On enlarging the side group, the d-spacing of the smectic layer increased, indicating folding packing of the polymer chains. Therefore, the adjacent phenyl rings in side groups stacked well together and formed strong π–π interactions even when the temperature was higher than Ti. The special structure of PBDPS could provide good mechanical properties. Thus, PBDPS exhibited the maximum tensile stress (28.6 MPa) and the highest elongation at break (1060%). Furthermore, the strong π–π interaction can act as netpoints; therefore, PBDPS exhibited excellent shape fixing (>99%) and shape recovery ratio (>99%) with large strain (>220%).
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![Ethanol, 2,2'-[[2-(6-oxido-6H-dibenz[c,e][1,2]oxaphosphorin-6-yl)-1,4-phenylene]bis(oxy)]bis-](/data/chemimg/3784500/102486-97-5_b.png)
![Ethanol, 2-[[[2-(1,1-dimethylethyl)-6-oxido-6H-dibenz[c,e][1,2]oxaphosphorin-6-yl]methyl](hydroxymethyl)amino]-](/data/chemimg/3784500/1228360-62-0.png)
![Ethanol, 2-[[[2-(1,1-dimethylethyl)-6-oxido-6H-dibenz[c,e][1,2]oxaphosphorin-6-yl]methyl](hydroxymethyl)amino]-](/data/chemimg/3784500/1228360-62-0_b.png)
![Ethanol, 2,2'-[[[2-(1,1-dimethylethyl)-6-oxido-6H-dibenz[c,e][1,2]oxaphosphorin-6-yl]methyl]imino]bis-](/data/chemimg/3784500/1228360-63-1.png)
![Ethanol, 2,2'-[[[2-(1,1-dimethylethyl)-6-oxido-6H-dibenz[c,e][1,2]oxaphosphorin-6-yl]methyl]imino]bis-](/data/chemimg/3784500/1228360-63-1_b.png)
![1,3-Benzenedicarboxylic acid, 5-[1,3-dihydro-1,3-dioxo-5-(2-phenylethynyl)-2H-isoindol-2-yl]-, 1,3-dimethyl ester](/data/chemimg/3784500/1776951-27-9.png)
![1,3-Benzenedicarboxylic acid, 5-[1,3-dihydro-1,3-dioxo-5-(2-phenylethynyl)-2H-isoindol-2-yl]-, 1,3-dimethyl ester](/data/chemimg/3784500/1776951-27-9_b.png)
![1,2-Benzenedicarboxylic acid, 4-[2-(1,3-dihydro-1,3-dioxo-5-isobenzofuranyl)ethynyl]-](/data/chemimg/3779100/1776951-28-0.png)
![1,2-Benzenedicarboxylic acid, 4-[2-(1,3-dihydro-1,3-dioxo-5-isobenzofuranyl)ethynyl]-](/data/chemimg/3779100/1776951-28-0_b.png)
![1,2-Benzenedicarboxylic acid, 4-[2-(2,3-dihydro-1,3-dioxo-2-phenyl-1H-isoindol-5-yl)ethynyl]-](/data/chemimg/3780500/1776951-29-1.png)
![1,2-Benzenedicarboxylic acid, 4-[2-(2,3-dihydro-1,3-dioxo-2-phenyl-1H-isoindol-5-yl)ethynyl]-](/data/chemimg/3780500/1776951-29-1_b.png)
![1,3-Benzenedicarboxylic acid, 5-[2-(1,3-dihydro-1,3-dioxo-5-isobenzofuranyl)ethynyl]-](/data/chemimg/3779100/1776951-30-4.png)
![1,3-Benzenedicarboxylic acid, 5-[2-(1,3-dihydro-1,3-dioxo-5-isobenzofuranyl)ethynyl]-](/data/chemimg/3779100/1776951-30-4_b.png)
![1,3-Benzenedicarboxylic acid, 5-[2-(2,3-dihydro-1,3-dioxo-2-phenyl-1H-isoindol-5-yl)ethynyl]-](/data/chemimg/3780500/1776951-31-5.png)
![1,3-Benzenedicarboxylic acid, 5-[2-(2,3-dihydro-1,3-dioxo-2-phenyl-1H-isoindol-5-yl)ethynyl]-](/data/chemimg/3780500/1776951-31-5_b.png)
![1,4-Benzenedicarboxylic acid, 2-[2-(1,3-dihydro-1,3-dioxo-5-isobenzofuranyl)ethynyl]-](/data/chemimg/3779100/1776951-32-6.png)
![1,4-Benzenedicarboxylic acid, 2-[2-(1,3-dihydro-1,3-dioxo-5-isobenzofuranyl)ethynyl]-](/data/chemimg/3779100/1776951-32-6_b.png)
![1,4-Benzenedicarboxylic acid, 2-[2-(2,3-dihydro-1,3-dioxo-2-phenyl-1H-isoindol-5-yl)ethynyl]-](/data/chemimg/3780500/1776951-33-7.png)
![1,4-Benzenedicarboxylic acid, 2-[2-(2,3-dihydro-1,3-dioxo-2-phenyl-1H-isoindol-5-yl)ethynyl]-](/data/chemimg/3780500/1776951-33-7_b.png)
![1,2-Benzenedicarboxylic acid, 4-[1,3-dihydro-1,3-dioxo-5-(2-phenylethynyl)-2H-isoindol-2-yl]-](/data/chemimg/3780500/1776951-34-8.png)
![1,2-Benzenedicarboxylic acid, 4-[1,3-dihydro-1,3-dioxo-5-(2-phenylethynyl)-2H-isoindol-2-yl]-](/data/chemimg/3780500/1776951-34-8_b.png)
![1,4-Benzenedicarboxylic acid, 2-[1,3-dihydro-1,3-dioxo-5-(2-phenylethynyl)-2H-isoindol-2-yl]-](/data/chemimg/3780500/1776951-35-9.png)
![1,4-Benzenedicarboxylic acid, 2-[1,3-dihydro-1,3-dioxo-5-(2-phenylethynyl)-2H-isoindol-2-yl]-](/data/chemimg/3780500/1776951-35-9_b.png)
![Ethanol, 2-[4-[4-[4-[4-(2-hydroxyethoxy)phenoxy]phenoxy]-2-phenoxyphenoxy]phenoxy]-](/data/chemimg/3784500/1799740-74-1.png)
![Ethanol, 2-[4-[4-[4-[4-(2-hydroxyethoxy)phenoxy]phenoxy]-2-phenoxyphenoxy]phenoxy]-](/data/chemimg/3784500/1799740-74-1_b.png)
![Phenol, 4-[4-[[6-[4-(acetyloxy)phenoxy][1,1'-biphenyl]-3-yl]oxy]phenoxy]-, 1-acetate](/data/chemimg/3784500/1799740-78-5.png)
![Phenol, 4-[4-[[6-[4-(acetyloxy)phenoxy][1,1'-biphenyl]-3-yl]oxy]phenoxy]-, 1-acetate](/data/chemimg/3784500/1799740-78-5_b.png)
