Co-reporter:Tuan Liu, Cheng Hao, Liwei Wang, Yuzhan Li, Wangcheng Liu, Junna Xin, and Jinwen Zhang
Macromolecules November 14, 2017 Volume 50(Issue 21) pp:8588-8588
Publication Date(Web):October 16, 2017
DOI:10.1021/acs.macromol.7b01889
Conventional epoxy polymers are constructed by petro-based resources that are toxic and nonrenewable, and their permanent cross-links make them difficult to be reprocessed, reshaped, and recycled. In this study, a unique eugenol-derived epoxy (Eu-EP) is synthesized, and then vitrimeric materials are prepared by reacting Eu-EP with succinic anhydride (SA) at various ratios (1:0.5, 1:0.75, and 1:1) in the presence of zinc-containing catalysts. All vitrimers exhibit excellent shape changing, crack healing, and shape memory properties. Although vitrimers with 1:0.75 and 1:1 ratios cannot be physically reprocessed, they can be well reprocessed by the chemical method of being simply decomposed in a benign ethanol solution without loading additional catalyst. The collected decomposed polymers can form vitrimers again after exposure at 190 °C for 3 h. This work combines the concepts of vitrimer preparation, chemical recycling, and biobased polymer together, which would bring a feasible way to satisfy the demands of sustainability.
Co-reporter:Xiaoxu Teng, Hui Xu, Wenjia Song, Jianwei Shi, Junna Xin, William C. Hiscox, and Jinwen Zhang
ACS Omega January 2017? Volume 2(Issue 1) pp:251-251
Publication Date(Web):January 25, 2017
DOI:10.1021/acsomega.6b00296
Sodium lignosulfonate (SLS) was aminated to obtain a lignin amine (LA) compound, which was subsequently crosslinked with poly(ethylene glycol) diglycidyl ether (PEGDGE) to obtain hydrogels. The chemical structure of the resulting LA-derived hydrogel (LAH) was characterized by Fourier transform infrared (FTIR) spectroscopy, solid-state 13C NMR spectroscopy, and elemental analysis, and the interior morphology of the freeze-dried hydrogel was examined by scanning electron microscopy. NMR and FTIR spectroscopy results indicated that the amino groups of LA reacted with PEGDGE in the crosslinking reaction. The lignin content in the resulting hydrogel increased with an increase in the LA/PEGDGE weight ratio in the reaction, approaching a maximum (∼71 wt %) and leveling off. The hydrogel with such a composition happened to be the same as the one prepared by reacting the primary amines of LA and epoxy groups of PEGDGE in equal stoichiometry. These results strongly suggest that the formation of the hydrogel network structure was largely dictated by the reactions between the primary amines and epoxy groups. The gels with lignin contents at this level exhibited a superior swelling capacity, viscoelasticity, and shear properties.Topics: Hydrogels; Hydrogels; Mechanical properties; Phase; Physical swelling; Polymer morphology;
Co-reporter:Tuan Liu;Xiaolong Guo;Wangcheng Liu;Cheng Hao;Liwei Wang;William C. Hiscox;Chengyun Liu;Can Jin;Junna Xin
Green Chemistry (1999-Present) 2017 vol. 19(Issue 18) pp:4364-4372
Publication Date(Web):2017/09/19
DOI:10.1039/C7GC01737E
Thermosetting polymers possess high dimensional stability, chemical resistance and thermal stability, and they are indispensable for many applications. However, conventional thermosetting polymers cannot be reprocessed and reshaped due to their permanent cross-linked structure. Therefore, recycling of thermosetting polymers is a serious challenge. Degrading thermosetting polymers into soluble oligomers and reuse of the oligomers in new resin systems may provide a favorable way to solve this problem. In this work, we developed an efficient method for chemical degradation of anhydride-cured epoxy using environmentally benign phosphotungstic acid (HPW) aqueous solution as the catalyst system at a mild reaction temperature of 190 °C. During reaction, the ester bond in the cross-linked structure was selectively cleaved, and the thermosetting polymer was fully converted to oligomers that contain multifunctional reactive groups. When the decomposed matrix polymer (DMP) was used as a reactive ingredient and added up to 40 wt% in the preparation of a new anhydride-cured epoxy curing system, the resulting cross-linked polymers still retained the mechanical properties of the neat polymer.
Co-reporter:Mahshid Maroufkhani, AliAsghar Katbab, Wangcheng Liu, Jinwen Zhang
Polymer 2017 Volume 115(Volume 115) pp:
Publication Date(Web):21 April 2017
DOI:10.1016/j.polymer.2017.03.025
•Elasticity and complex viscosity of NBR increased with ACN content.•Slopes of Cole-Cole and Han plots of PLA/NBR for lower ACN is higher.•Interfacial tension between PLA and NBR increased with ACN content.•Rubber particle size increased with ACN content.•Impact strength and elongation properties of the blend significantly improved by adding 10 wt% NBR.In this study, attempts have been put to prepare toughened polylactide (PLA) through melt blending with acrylonitrile butadiene rubber (NBR) via melt mixing process. The influences of acrylonitrile (ACN) content on the compatibility, microstructure, tensile properties and impact resistance have been investigated. A matrix-dispersed droplet morphology was noted for all blend samples, and the rubber particle size decreased with decreasing ACN content of NBR. This droplet size, impact strength and elongation all corresponded well to the interfacial interaction that was evidenced by surface tension analysis and melt rheology. It was noted that the interfacial tension decreased with decrease in ACN content, accordingly, the results from both Cole-Cole curves and Han plots indicated high homogeneity of the PLA blend with NBR containing lower ACN contents. On the other hand, all blends exhibited very similar glass transition temperatures and crystallinity. It is concluded that extent of thermodynamic compatibility of PLA and NBR determines the improvement of toughness. Incorporation of only 10 wt% NBR resulted in dramatic improvements of elongation at break and impact strength of PLA and largely retained the high tensile strength of neat PLA.Download high-res image (153KB)Download full-size image
Co-reporter:Tuan Liu, Meng Zhang, Xiaolong Guo, Chengyun Liu, Tian Liu, Junna Xin, Jinwen Zhang
Polymer Degradation and Stability 2017 Volume 139(Volume 139) pp:
Publication Date(Web):1 May 2017
DOI:10.1016/j.polymdegradstab.2017.03.017
Carbon fiber reinforced polymers (CFRPs) with high Tg (>200 °C) are indispensable for aerospace industry where high service temperature is required. Chemical recycling of the matrix polymers for these CFRP composites is more difficult than that of their low Tg analogues. In this work, an efficient approach for mild chemical recycling of CFRP with a Tg of ∼210 °C was developed using a ZnCl2/ethanol catalyst system. The high efficiency of ZnCl2/ethanol was attributed to the strong coordination effect of ZnCl2 with the C-N bonds and the strong swelling ability of ethanol, which worked together to break down the chemical bonds of the cross-linked polymer. Also, mild degradation temperature (<200 °C) imparted little damage to the recovered fibers. The decomposed matrix polymer (DMP) was in the oligomer form and contained multifunctional reactive groups. When DMP was used as a reactive ingredient and added up to 15 wt% to the preparation of new epoxy materials, the resulting cross-linked polymers could still retain the high strength and modulus compared to the neat polymer without addition of DMP.
Co-reporter:Wenjia Song, Junna Xin, Jinwen Zhang
Industrial Crops and Products 2017 Volume 100(Volume 100) pp:
Publication Date(Web):1 June 2017
DOI:10.1016/j.indcrop.2017.02.018
•Soy protein-poly(acrylic acid) hydrogel was prepared via a macromonomer approach.•The use of SP macro-crosslinker eliminated the need for another crosslinker.•The mechanical properties were significantly improved by the macromonomer approach.•Extractable SP was reduced by the macromonomer approach.•SP to acrylic acid ratio was 1/3 and the final SP content in the gel was 11–19%.A soy protein (SP)-poly(acrylic acid) (PAA) superabsorbent hydrogel was synthesized from soy protein isolate and potassium acrylate. Alkali-treated SP was turned into macromonomer through the functionalization of its primary amine groups using methacrylic anhydride. The SP-PAA hydrogel was formed by free radical copolymerization of the SP macromonomer and potassium acrylate monomer. It was demonstrated that the SP macromonomer acted as a macro-crosslinker and no additional crosslinker was needed. The whole synthesis was conducted in a one-pot process. The chemical structure and degree of functionalization of the SP macromonomer were characterized by 1H NMR spectroscopy and UV–vis spectrophotometry, respectively. The SP to acrylic acid weight ratio at the preparation of the hydrogel was 1/3 and the SP content in the final product was 11–19%. As a result of the functionalization of SP, compressive gel strength was significantly improved, gel content was increased and extractable SP was reduced. Free swelling in distilled water was reduced for SP macromonomer gels due to increased crosslink density. The SP-PAA hydrogels displayed a stable swelling performance in buffer solutions with pH ranging from 6 to 11.5.Download high-res image (93KB)Download full-size image
Co-reporter:Junna Xin, Mei Li, Ran Li, Michael P. Wolcott, and Jinwen Zhang
ACS Sustainable Chemistry & Engineering 2016 Volume 4(Issue 5) pp:2754
Publication Date(Web):April 5, 2016
DOI:10.1021/acssuschemeng.6b00256
In this work, lignin-based epoxy was synthesized by reacting epichlorohydrin (ECH) and partially depolymerized lignin (PDL) and then used for modification of asphalt. The Diels–Alder adduct of methyl esters of eleostearic acid and maleic anhydride (ME-MA) was synthesized and used as a biobased curing agent. The structure of PDL-epoxy was characterized by FTIR and 31P NMR. Nonisothermal curing kinetics and thermal properties of the cured epoxy resins were studied by differential scanning analysis, dynamic mechanical analysis, and thermogravimetric analysis, respectively. Curing behaviors of PDL-epoxy and a commercial epoxy DER332 were compared. Effects of epoxy content on rheological properties of the modified asphalt binder were studied using a parallel plate rheometer. Results show that the elastic behavior of asphalt binder at elevated temperatures was improved with increase in epoxy content.Keywords: Epoxy asphalt; Green epoxy resin; Lignin; Lignin-based epoxy
Co-reporter:Xiaojie Guo, Jinwen Zhang, Jijun Huang
Polymer 2015 Volume 69() pp:103-109
Publication Date(Web):9 July 2015
DOI:10.1016/j.polymer.2015.05.050
•PLA/POM blends were prepared through melt compounding.•The HDT of the blend with 50% POM (133 °C) was about twice that of the neat PLA (65 °C).•The tensile modulus exhibited a synergistic effect, as the blend had a greater modulus than neat PLA or POM.•The stacked phase structure of the blends resulted in enhanced HDT and superior mechanical performance.Poly(lactic acid)/polyoxymethylene (PLA/POM) blends were prepared through melt compounding in an attempt to improve the heat resistance of PLA. The effects of POM on the immiscibility, dynamic and quasi-static mechanical properties, rheological properties, and heat resistance were examined in detail with various techniques. PLA was found to be immiscible with POM, evidenced by both phase-separated morphology and two glass transition temperatures of the blends. The heat deflection temperature of PLA was nearly doubled, increasing from 65 to 133 °C, when the POM content approaches 50%. The tensile modulus exhibited a synergistic effect, as the blend has a greater modulus than neat PLA or POM. Because the PLA in the injection molded test samples was totally amorphous as revealed by the WXRD result, the enhanced HDT and superior mechanical properties were mainly attributed to the unique stacked layer structure of the blends.
Co-reporter:Jia Cheng, Pei Zhang, Tao Liu, Jinwen Zhang
Polymer 2015 Volume 78() pp:212-218
Publication Date(Web):5 November 2015
DOI:10.1016/j.polymer.2015.10.009
Co-reporter:Yu Fu, Linshu Liu, and Jinwen Zhang
ACS Applied Materials & Interfaces 2014 Volume 6(Issue 16) pp:14069
Publication Date(Web):July 4, 2014
DOI:10.1021/am503283f
This study aimed to enhance the conductive properties of PLA nanocomposite by controlling the dispersion and distribution of graphene within the minor phase of the polymer blend. Functionalized graphene (f-GO) was achieved by reacting graphene oxide (GO) with various silanes under the aid of an ionic liquid. Ethylene/n-butyl acrylate/glycidyl methacrylate terpolymer elastomer (EBA-GMA) was introduced as the minor phase to tailor the interface of matrix/graphene through reactive compatibilization. GO particles were predominantly dispersed in PLA in a self-agglomerating pattern, while f-GO was preferentially located in the introduced rubber phase or at the PLA/EBA-GMA interfaces through the formation of the three-dimensional percolated structures, especially for these functionalized graphene with reactive groups. The selective localization of the f-GO also played a crucial role in stabilizing and improving the phase morphology of the PLA blend through reducing the interfacial tension between two phases. The establishment of the percolated network structures in the ternary system was responsible for the improved AC conductivity and better dielectric properties of the resulting nanocomposites.Keywords: conductivity; dispersion; functionalization; graphene; nanocomposites; polylactic acid
Co-reporter:Pei Zhang, Junna Xin, and Jinwen Zhang
ACS Sustainable Chemistry & Engineering 2014 Volume 2(Issue 2) pp:181
Publication Date(Web):October 13, 2013
DOI:10.1021/sc400206t
Unlike the conventional synthesis of acrylated soybean oil (ASO) that usually involved several steps, a novel one-step reaction synthesis of ASO was introduced in this study. ASO was prepared directly from the addition reaction of soybean oil (SO) and acrylic acid (AA). Effects of catalyst type, reaction stoichiometry, and conditions of the one-step synthesis of ASO were investigated in detail. The products were characterized using 1H NMR, 13C NMR, and FTIR. BF3·Et2O was found to be the most effective catalyst for this addition reaction. The results indicated that high catalyst and AA concentrations greatly increased the conversion to ASO and accelerated the reaction. Side reactions, such as polymerization of AA and transesterification between triglycerides and AA, were also noted during the reaction and were examined using 1H NMR. The feasibility of recovering and reusing the catalyst and excess AA was evaluated.Keywords: Acrylated soybean oil; Acrylation; Biobased polymers; Soybean oil
Co-reporter:Jianglei Qin, Michael Woloctt, and Jinwen Zhang
ACS Sustainable Chemistry & Engineering 2014 Volume 2(Issue 2) pp:188
Publication Date(Web):October 3, 2013
DOI:10.1021/sc400227v
In this study, Kraft lignin was partially depolymerized through base catalyzed depolymerization (BCD) in supercritical methanol to increase its solubility in organic solvents. The resulting partially depolymerized lignin (PDL) was then converted to lignin-based polycarboxylic acid (LPCA) by reacting with succinic anhydride. The hydroxyl value of PDL and acid value of LPCA were determined using 31P NMR. LPCA was used as a curing agent to cure a commercial epoxy (DER353). Because LPCA was a soft solid, glycerol tris(succinate monoester) (GTA) which was liquid at room temperature was also synthesized and used as cocuring agent and a diluent for LPCA. Dynamic mechanical properties and thermal stability of the cured epoxy resins were examined using dynamic mechanical analysis and thermogravimetric analysis, respectively. Results showed that curing of DER353 with the LPCA resulted in an epoxy resin with a moderate glass transition temperature (Tg) and a storage modulus comparable to the resin cured with the commercial hexahydrophthalic anhydride (HHPA). However, thermal and thermal mechanical properties of the cured resins could be greatly regulated by using GTA or HHPA as a cocuring agent.Keywords: Biobased material; Curing agent; Lignin; Polycarboxylic acid
Co-reporter:Xiaojie Guo, Hongzhi Liu, Jinwen Zhang, and Jijun Huang
Industrial & Engineering Chemistry Research 2014 Volume 53(Issue 43) pp:16754-16762
Publication Date(Web):2017-2-22
DOI:10.1021/ie502104y
In this work, use of polyoxymethylene (POM) as a polymeric nucleating agent for poly(lactic acid) (PLA) was studied. The compounding was performed using a twin-screw extruder. Effects of POM on isothermal crystallization of PLA at temperatures ranging from 106 °C to 111 °C and visible transmittance of PLA were examined in detail with various techniques, including polarized optical microscopy, differential scanning calorimetry (DSC), X-ray diffraction (XRD), and ultraviolet–visible (UV-vis) spectroscopy. Banded spherulites were noted when the POM content exceeded 5 wt %. The presence of POM generally resulted in effective reductions in the half time of crystallization and the spherulite size of PLA. However, 1% POM was a threshold for the nucleating effect: at ≤1% POM, no nucleating effect was observed. Fourier transform infrared (FTIR) spectroscopy revealed the strong interaction between the two polymers. The Avrami modeling suggested a three-dimensional crystal growth at all temperatures and loading levels of POM. Although POM does not accelerate the crystallization of PLA as fast as some of the inorganic nucleating agents such as talc, it imparts PLA the nucleating effect without sacrificing transparency.
Co-reporter:Mei Li, Jianchun Jiang, Jinwen Zhang, Xiaohua Yang, Yan Zhang, Shouhai Li, Jian Song, Kun Huang, Jianling Xia
Polymer Degradation and Stability 2014 Volume 109() pp:129-136
Publication Date(Web):November 2014
DOI:10.1016/j.polymdegradstab.2014.07.008
In this work, a new liquid thermal stabilizer (LTS) was prepared using rosin and fatty acids as feedstock and evaluated for its stabilizing effects on poly(vinyl chloride) (PVC). First, a rosin/oil-based dimer acid (RODA) was prepared by the addition reaction of rosin and industrial fatty acids and then converted into its zinc soap (RODA-Zn) and calcium soap (RODA-Ca). The chemical structures were examined by UV–Vis and Fourier Transform infrared spectroscopies. Liquid form thermal stabilizers (RODA-LTS) were obtained by treating the solid RODA-Zn and RODA-Ca soaps with epoxidized soybean oil, triphenyl phosphite and liquid paraffin at 120 °C for 3 h. Thermal stabilizing effects of the resulting RODA-LTS for PVC were compared with that of two commercial LTSs. Thermal stability of PVC compounds was determined using dehydrochlorination test, thermogravimetric analysis (TGA), Congo red test and torque rheological analysis. Results indicated that RODA-LTS had overall superior thermal stability. Tensile and dynamic mechanical properties of the PVC compounds were also studied, and the results indicated that the PVC compounds stabilized with RODA-LTS and commercial LTSs displayed comparable strength, modulus and glass transition temperatures.
Co-reporter:Gustavo F. Brito, Junna Xin, Pei Zhang, Tomás J. A. Mélo and Jinwen Zhang
RSC Advances 2014 vol. 4(Issue 50) pp:26425-26433
Publication Date(Web):06 Jun 2014
DOI:10.1039/C4RA03607G
In this work, for the first time, redox initiation was employed in the melt free radical grafting of glycidyl methacrylate (GMA) and maleic anhydride (MA) onto polyethylene (PE) by reactive extrusion. Since it is very challenging to obtain high grafting degrees of GMA and MA onto polymer backbones through conventional free radical initiation, especially in the extrusion process, the strategy of using a peroxide/reducing agent initiator was introduced. The redox initiation system was composed of dicumyl peroxide (DCP) and Tin(II) 2-ethylhexanoate (Sn(Oct)2). The grafting reaction was monitored by torque rheometry and graft products were analyzed by Fourier Transform Infrared Spectroscopy. Effects of monomer concentration and DCP/Sn(Oct)2 ratio on the degree of grafting were studied. The redox initiation proved to be very effective in improving the grafting degree of GMA and MA onto PE. It is reasoned that, in the presence of Sn(Oct)2, the free radicals produced were not subject to a cage effect, yielding high initiator efficiency.
Co-reporter:Xiaoping Rao, Jinwen Zhang, Jianqiang Zheng, Zhanqian Song and Shibin Shang
RSC Advances 2014 vol. 4(Issue 48) pp:25334-25340
Publication Date(Web):29 May 2014
DOI:10.1039/C4RA01510J
Renewable chiral bulky rigid D- and L-camphorsulfonic acids were introduced as new building blocks in the design of ionic liquid crystals with long chain alkylamines (CnH2n+1NH2; n = 12, 14, 16 and 18) by the direct reaction of acid and amine. The phase transition behaviors of the obtained salts were investigated using DSC, POM, FTIR, XRD and CD spectroscopy, respectively. The salts with shorter alkyl chain lengths exhibited lower liquid crystal transition temperatures and wider mesophase ranges. The vibration of the N–H bonds was weakened or even disappeared with increasing temperature, which was probably due to the decrease in the change of dipole moment of the liquid crystals.
Co-reporter:Junna Xin, Pei Zhang, Kun Huang and Jinwen Zhang
RSC Advances 2014 vol. 4(Issue 17) pp:8525-8532
Publication Date(Web):16 Jan 2014
DOI:10.1039/C3RA47927G
An epoxy based on cinnamic acid (Cin-epoxy) and an anhydride curing agent based on dipentene were prepared. Both products are liquids of low viscosity at room temperature. For the synthesis of the epoxy, cinnamic acid was first converted to a diacid by reacting with maleic anhydride via Friedel–Crafts reaction, followed by allylation of the carboxylic groups and subsequent epoxidation of the allyl double bonds. The curing agent was the Diels–Alder adduct of dipentene and maleic anhydride (DPMA). The chemical structures of Cin-epoxy and DPMA were confirmed by 1H NMR, 13C NMR, FT-IR and ESI-MS. Non-isothermal curing of Cin-epoxy was studied using differential scanning calorimetry (DSC). In addition to DPMA, two commercial anhydrides were also used to cure Cin-epoxy and the curing reactivity and properties of cured resins were compared. Thermal mechanical properties and thermal stability of the cured epoxy resins were studied using dynamic mechanical analysis (DMA) and thermogravimetric analysis (TGA), respectively. Results showed that Cin-epoxy was slightly more reactive than the bisphenol A type epoxy DER 332 and displayed good dynamic mechanical properties and thermal stability.
Co-reporter:Jianglei Qin;Hongzhi Liu;Pei Zhang;Michael Wolcott
Polymer International 2014 Volume 63( Issue 4) pp:760-765
Publication Date(Web):
DOI:10.1002/pi.4588
Abstract
In this study, an epoxy based on eugenol and an anhydride curing agent based on rosin were prepared. Curing of the eugenol epoxy with a commercial anhydride curing agent and with the rosin-derived anhydride curing agent was studied. For comparison, a commercial bisphenol A type epoxy, DER353, was also selected in the curing study. The syntheses of the eugenol epoxy and rosin anhydride were investigated and the chemical structures of the products and intermediates were characterized using 1H NMR and Fourier transform infrared spectroscopies. Non-isothermal curing of the eugenol epoxy with hexahydrophthalic anhydride and the rosin-derived maleopimaric acid was studied using differential scanning calorimetry. Thermomechanical properties and thermal stability of the cured epoxy resins were evaluated using dynamic mechanical analysis and thermogravimetric analysis, respectively. Addition of 2-ethyl-4-methylimidazole as catalyst greatly decreased the curing temperature and promoted the completion of cure reactions. The results suggest that the eugenol epoxy and the bisphenol A type epoxy have similar reactivity, dynamic mechanical properties and thermal stability. © 2013 Society of Chemical Industry
Co-reporter:Kun Huang, Zengshe Liu, Jinwen Zhang, Shouhai Li, Mei Li, Jianling Xia, and Yonghong Zhou
Biomacromolecules 2014 Volume 15(Issue 3) pp:
Publication Date(Web):February 2, 2014
DOI:10.1021/bm4018929
A novel biobased epoxy monomer with conjugated double bonds, glycidyl ester of eleostearic acid (GEEA) was synthesized from tung oil fatty acids and characterized by 1H and 13C NMR. Differential scanning calorimeter analysis (DSC) and Fourier transform infrared spectroscopy (FT-IR) were utilized to investigate the curing process of GEEA with dienophiles and anhydrides. DSC indicated that GEEA could cross-link with both dienophiles and anhydrides through Diels–Alder reaction and epoxy/anhydride ring-opening reaction. Furthermore, Diels–Alder cross-link was much more active than the ring-opening of epoxy and anhydride in the curing process. FT-IR also revealed that GEEA successively reacted with dienophiles and anhydrides in both cross-linking methods. Dynamic mechanical analysis and mechanical tensile testing were used to study the thermal and mechanical properties of GEEA cured by maleic anhydride, nadic methyl anhydride and 1,1′-(methylenedi-4,1-phenylene)bismaleimide. Due to the independence between the curing agents, dienophile and anhydride, a series of thermosetting polymers with various properties could be obtained by adjusting the composition of these two curing agents.
Co-reporter:Yu Fu, Linshu Liu, Jinwen Zhang, William C. Hiscox
Polymer 2014 Volume 55(Issue 24) pp:6381-6389
Publication Date(Web):18 November 2014
DOI:10.1016/j.polymer.2014.10.014
•Five silanes with different functional groups were employed to modify the graphene through a novel one-step method.•An effective strategy for engineering the interfacial compatibility between graphene and PLA was developed.•Curing between functionalized graphene and the elastomer modifier resulted in controlled dispersion and distribution of graphene.•The percolated structures are the origin of the improved properties of nanocomposites.•The mechanism on property tailoring is from interface engineering through dual modifiers.In this work, an effective strategy for engineering the interfacial compatibility between graphene and polylactic acid (PLA) was developed by manipulating the functionalization of graphene and introducing an epoxy-containing elastomer modifier. Curing between the functional groups of the modified graphene and the epoxy groups of the elastomer modifier resulted in controlled dispersion and distribution of graphene in the composite system and hence improved the interfacial adhesion between PLA and graphene. Effects of different graphene functionalization with polymer toughener on morphology, viscoelasticity, and thermal properties of the resulting PLA nanocomposites were thoroughly examined. The resulting percolated structures were the origin of the improved properties of PLA/graphene nanocomposites. The mechanism on property tailoring from interface engineering through dual modifiers are also proposed. Overall, the insight into the interface engineering between the functionalized graphene and the matrix through an elastomer modifier offers a novel way for the future design of graphene polymer nanocomposites.
Co-reporter:Shifeng Deng;Jia Cheng;Xiaojie Guo;Long Jiang
Journal of Polymers and the Environment 2014 Volume 22( Issue 1) pp:17-26
Publication Date(Web):2014 March
DOI:10.1007/s10924-013-0617-8
The effects of ionic liquid BMIMCL (1-buthyl-3-methyl-imidazolium-chloride) on the solution of soy protein isolate (SPI) were first studied. In situ polymerization of acrylonitrile monomer in the presence of SPI was conducted in a BMIMCL/dimethyl sulfoxide (DMSO) mixture solvent to produce SPI-g-PAN. This graft polymer was blended with pure PAN in BMIMCL/DMSO (1:5) and spun into fiber using a wet spinning method. The effects of SPI content and solution temperature on the viscoelasticity of the spinning dope were studied. FTIR, DSC and solution studies were used to confirm the grafting of PAN. Microstructure and mechanical properties of the spun fibers under different draw ratios were investigated.
Co-reporter:Pei Zhang and Jinwen Zhang
Green Chemistry 2013 vol. 15(Issue 3) pp:641-645
Publication Date(Web):23 Jan 2013
DOI:10.1039/C3GC36961G
In this work, a novel efficient one-step method for preparation of acrylated soybean oil (ASO) was introduced. ASO was obtained by reacting soybean oil (SO) and acrylic acid (AA) directly under the catalysis of BF3·Et2O. Effects of reaction stoichiometry and reaction time on the conversion of the double bonds of SO were studied. 1H NMR analysis indicated that the number of acrylate groups could reach 3.09 per triglyceride molecule or the conversion of the double bonds was up to ∼75.7%. Copolymerization of the ASO and styrene was demonstrated, and the flexural and dynamic mechanical properties of the resulting polymers were evaluated.
Co-reporter:Kun Huang, Pei Zhang, Jinwen Zhang, Shouhai Li, Mei Li, Jianling Xia and Yonghong Zhou
Green Chemistry 2013 vol. 15(Issue 9) pp:2466-2475
Publication Date(Web):25 Jun 2013
DOI:10.1039/C3GC40622A
In this work, a 21-carbon dicarboxylic acid (C21DA) and a 22-carbon tricarboxylic acid (C22TA) were prepared by the Diels–Alder addition of tung oil fatty acids with acrylic acid and fumaric acid, respectively, and subsequently converted to the corresponding di- and triglycidyl esters. There were no solvents used in the addition and glycidylation reactions. The excess epichlorohydrin used in the latter reaction could be recovered and reused. Furthermore, for the first time, calcium oxide was introduced as a water scavenger in the glycidylation process to effectively avoid the side reactions. The chemical structures of the products were confirmed using 1H NMR, 13C NMR and ESI-MS analyses. The curing behaviors of the di- and triglycidyl esters were studied using differential scanning calorimetry. Flexural, impact and dynamic mechanical properties of the cured resins were also determined. A commercial bisphenol A epoxy DER 332 and an epoxidized soybean oil (ESO) were used as controls in the study. Results indicated that the obtained diglycidyl and triglycidyl esters had overall superior performance to that of ESO for epoxy applications. Particularly, the triglycidyl ester of the C22TA displayed comparable strength, modulus and glass transition temperature to that of DER332.
Co-reporter:Yu Fu, Jinwen Zhang, Hang Liu, William C. Hiscox and Yi Gu
Journal of Materials Chemistry A 2013 vol. 1(Issue 7) pp:2663-2674
Publication Date(Web):11 Dec 2012
DOI:10.1039/C2TA00353H
A novel one-step approach for the pH-triggered electrochemically interacted exfoliation of graphene sheets in graphite oxide and simultaneous reduction and functionalization with the aid of the ionic liquid is reported. The developed method shows significant advantages over the conventional functionalized/chemically reduced graphene. Particularly, for the first time, no additional stabilizer or modifier is needed to stabilize the resulting processible graphene dispersion. The prepared graphene oxide and its functionalized graphene are characterized by SEM, TEM, FTIR, UV-vis, XRD, Raman, XPS, and NMR. The results indicate that, with the aid of the IL during the reaction, the resulting functionalized graphene shows improved organophilicity, good wettability and improved interfacial interactions as well as significant resistance to thermal degradation. The methodology paves a new way for use of the IL as a processing aid and reaction medium to promote chemical functionalization of graphene through the electrochemically interacted exfoliation of graphene sheets and can be expected to provide a new approach with great promise for its organophilic wettability and enhanced interfacial adhesion as well as improved thermal stability. Furthermore, the controlled modifications of graphene nanoreinforcements can also be expected to alter the nature of the interactions between components.
Co-reporter:Hongzhi Liu, Xiaojie Guo, Wenjia Song, and Jinwen Zhang
Industrial & Engineering Chemistry Research 2013 Volume 52(Issue 13) pp:4787
Publication Date(Web):March 9, 2013
DOI:10.1021/ie303317k
In this study, toughening of poly(lactic acid) (PLA) through reactive blending with epoxy-containing elastomer and ionomer was investigated. Four commercial ionomers based on the poly(ethylene-co-methacrylic acid) (EMAA) precursor were evaluated in this study, which contained zinc, magnesium, sodium, an lithium ions, respectively. Effects of metal ion type, elastomer/ionomer weight ratio and blending temperature on impact toughness of PLA ternary blends were studied. The toughening effects of metal ions of the ionomers is in the order of Zn > Mg > Li ≈ Na. High blending temperature and high elastomer/ionomer ratio both promoted the effective toughening of the PLA ternary blends. The reactive compatibilization and cross-linking of the epoxy-containing elastomer were analyzed using FT-IR, SEM, dynamic mechanical analysis, and torque rheology. In addition, the effect of metal ion type on thermal degradation of PLA was also examined.
Co-reporter:Scott Anderson;Michael P. Wolcott
Journal of Polymers and the Environment 2013 Volume 21( Issue 3) pp:631-639
Publication Date(Web):2013 September
DOI:10.1007/s10924-013-0586-y
To explore the commercial viability of Polyhydroxybutyrate (PHB)/wood flour (WF) composites, systems were produced at industry-standard levels of fiber loading. Further, four interfacial modifiers were selected to improve the mechanical properties of PHB/WF composites, including maleated PHB (PHB-g-MA), a low molecular weight epoxy, a low molecular weight polyester, and polymethylene-diphenyl-diisocyante (pMDI). Results showed that all modifiers resulted in improvements in tensile strength and modulus, however, pMDI showed the highest improvements. The pMDI modifier also improved water uptake of the composites. Study of the fracture surfaces showed signs of improved fiber bonding, as did morphological studies by dynamic mechanical analysis (DMA), and differential scanning calorimetry (DSC). Interpretation of the DSC and DMA results indicate possible reactions with lubricant, and interactions between PHB and wood fibers with the addition of pMDI.
Co-reporter:Rui Zhu, Hongzhi Liu, and Jinwen Zhang
Industrial & Engineering Chemistry Research 2012 Volume 51(Issue 22) pp:7786-7792
Publication Date(Web):May 18, 2012
DOI:10.1021/ie300118x
Poly(lactic acid) (PLA)/soy protein concentrate (SPC) composites were prepared using a twin-screw extruder. Extra amounts of water and glycerol were added to SPC prior to compounding with PLA to ensure that SPC behaved like a thermoplastic during subsequent mixing. Free radical grafting of maleic anhydride (MA) onto PLA was performed by reactive extrusion, and PLA-g-MA was used as a compatibilizer in the composites. The effects of compatibilizer concentration and degree of functionality on the tensile, morphological, and thermal properties of PLA/SPC composites were studied. The tensile strength of the composites containing 4 phr compatibilizer increased by 19% compared to that of the uncompatibilized one. Also, the presence of compatibilizer resulted in finer domain sizes of SPC and a lower damping peak, both of which suggested that good interfacial adhesion between the two phases was achieved. Differential scanning calorimetry analysis indicated that SPC induced and accelerated cold crystallization of PLA.
Co-reporter:Elvie E. Brown;Marie-Pierre G. Laborie
Cellulose 2012 Volume 19( Issue 1) pp:127-137
Publication Date(Web):2012 February
DOI:10.1007/s10570-011-9617-9
Bacterial cellulose/fibrin composites were treated with glutaraldehyde in order to crosslink the polymers and allow better match of the mechanical properties with those of native small-diameter blood vessels. Tensile and viscoelastic properties of the glutaraldehyde treated composites were determined from tensile static tests and cyclic creep tests, respectively. Glutaraldehyde-treated (bacterial cellulose) BC/fibrin composites exhibited tensile strength and modulus comparable to a reference small-diameter blood vessel; namely a bovine coronary artery. However, the breaking strain of the glutaraldehyde-treated composites was still well below that of the native blood vessel. Yet a long strain hardening plateau was induced by glutaraldehyde treatment which resembled the stress–strain response of the native blood vessel. Tensile cyclic creep test indicated that the time-dependent viscoelastic behavior of glutaraldehyde-treated BC/fibrin composites was comparable to that of the native blood vessel. Covalent bonding between BC and fibrin occurred via glutaraldehyde, affording mechanical properties comparable to that of the native small blood vessel.
Co-reporter:Hongzhi Liu, Li Guo, Xiaojie Guo, Jinwen Zhang
Polymer 2012 Volume 53(Issue 2) pp:272-276
Publication Date(Web):24 January 2012
DOI:10.1016/j.polymer.2011.12.036
Reactive blending of poly(lactic acid) (PLA) with an ethylene/n-butyl acrylate/glycidyl methacrylate terpolymer elastomer (EBA-GMA) and a zinc ionomer of ethylene/methacrylic acid copolymer (EMAA-Zn) was performed at various temperatures using a twin screw extruder. Notched Izod impact strength, dynamic mechanical properties and morphological structure of the resulting blends were studied. A sharp brittle–ductile transition (BDT) of the resulting blends occurred when the blending temperature increased to 195∼210 °C and the EBA-GMA/EMAA-Zn ratio was equal to or large than 1. The influences of blending temperature on interfacial compatibilization and croslinking of the elastomer were also studied. Supertough PLA ternary blends were achieved by this reactive approach.
Co-reporter:Wenjia Song, Hongzhi Liu, Feng Chen, Jinwen Zhang
Polymer 2012 Volume 53(Issue 12) pp:2476-2484
Publication Date(Web):25 May 2012
DOI:10.1016/j.polymer.2012.03.050
Toughening of poly(lactic acid) (PLA) was studied by reactive blending PLA with ethylene/n-butyl acrylate/glycidyl methacrylate (EBA-GMA) terpolymer and zinc ion-containing ionomer. The ionomer was prepared by neutralizing the ethylene/methacrylic acid copolymer (EMAA), i.e., ionomer precursor, with ZnO. The reactive interfacial compatibilization between PLA and EBA-GMA and the crosslinking of EBA-GMA during blending was studied in detail. Fractography and FT-IR analysis indicated that both the degree of neutralization (DN) of ionomer and methacrylic acid (MAA) content of ionomer precursor exhibited significant effects on interfacial compatibilization. Dynamic mechanical analysis also suggested that the crosslinking level of EBA-GMA varied with these two factors. Particle size and polydispersity of the dispersed phase were measured by image analysis of TEM micrographs of the ternary blends and correlated with the impact strength of the blends and the characteristics of the ionomer. Ionomers derived from precursor of high MAA content and/or having high DN tended to yield superior impact strength of the PLA blends.Graphical abstract
Co-reporter:Xiaoqing Liu, Yi Wang, Yang Cao, Vikram Yadama, Ming Xian, Jinwen Zhang
Carbohydrate Polymers 2011 Volume 83(Issue 3) pp:1180-1184
Publication Date(Web):30 January 2011
DOI:10.1016/j.carbpol.2010.09.019
In this study, a water-soluble dextrin derivative was synthesized by reacting dextrin with trimellitic anhydride. The chemical structure of the dextrin-derived curing agent was confirmed by FT-IR and 1H NMR. The dextrin derivative contained free carboxylic acid groups and was used as curing agent for waterborne epoxy in wood bonding test. The adhesion of wood bonded by this waterborne epoxy system was studied and compared with that of wood bonded by phenol–formaldehyde resin. Results showed that the two adhesive systems displayed very similar block shear strengths and specimen failures. The two types of adhesives also showed similar extents of resin penetration into the wood substrate. This study demonstrated that starch or dextrin could be used as an economic feedstock for synthesis of curing agents for waterborne epoxies in the effort to develop formaldehyde free and volatile organic compounds (VOC)-free wood adhesives.
Co-reporter:Bo Liu;Long Jiang
Macromolecular Materials and Engineering 2011 Volume 296( Issue 9) pp:835-842
Publication Date(Web):
DOI:10.1002/mame.201000449
Co-reporter:Bo Liu, Sachin Bhaladhare, Peng Zhan, Long Jiang, and Jinwen Zhang , Linshu Liu and Arland T. Hotchkiss
Industrial & Engineering Chemistry Research 2011 Volume 50(Issue 24) pp:13859-13865
Publication Date(Web):November 8, 2011
DOI:10.1021/ie2017948
In this work, sugar beet pulp (SBP), the residue remaining after sugar extraction, was first turned into a thermoplastic-like compound by extrusion in the presence of water and glycerol. The resulting thermoplastic SBP (TSBP) was then blended with poly(butylene adipate-co-terepthalate) (PBAT) and extruded into sheets in a single process. The effects of polymeric diphenyl methane diisocyanate (pMDI) as compatibilizer and TSBP content on rheological properties, phase morphology, mechanical properties, and water absorption of the extruded sheets were studied. In comparison, dried SBP powder was also blended with PBAT by extrusion. It was found that when SBP was used as a plastic in compounding, it yielded blends with much finer dispersion of the SBP phase than when SBP was used as a filler in compounding. The dispersion of SBP in the blends was greatly improved with the addition of pMDI. The PBAT/SBP blends with fine phase morphology showed enhanced mechanical properties and moisture resistance.
Co-reporter:Hongzhi Liu, Wenjia Song, Feng Chen, Li Guo, and Jinwen Zhang
Macromolecules 2011 Volume 44(Issue 6) pp:1513-1522
Publication Date(Web):February 16, 2011
DOI:10.1021/ma1026934
Polyactide (PLA) was blended with an ethylene/n-butyl acrylate/glycidyl methacrylate (EBA-GMA) terpolymer and a zinc ionomer of ethylene/methacrylic acid (EMAA-Zn) copolymer. The phase morphology of the resulting ternary blends and its relationship with impact behaviors were studied systematically. Dynamic vulcanization of EBA-GMA in the presence of EMAA-Zn was investigated by torque rheology, and its cross-link level was evaluated by dynamic mechanical analysis. Reactive compatibilization between PLA and EBA-GMA was studied using Fourier transform infrared spectroscopy. The dispersed domains in the ternary blends displayed a “salami”-like phase structure, in which the EMAA-Zn phase evolved from occluded subinclusions into continuous phase with decrease in the EBA-GMA/EMAA-Zn ratio. An optimum range of particle sizes of the dispersed domains for high impact toughness was identified. Also, the micromechanical deformation process of these ternary blends was also investigated by observation of the impact-fractured surfaces using the electron microscope. It was suggested that the low cavitation resistance of dispersed particles in conjunction with suitable interfacial adhesion was responsible for the optimum impact toughness observed.
Co-reporter:Hongzhi Liu
Journal of Polymer Science Part B: Polymer Physics 2011 Volume 49( Issue 15) pp:1051-1083
Publication Date(Web):
DOI:10.1002/polb.22283
Abstract
Renewable poly(lactic acid) (PLA) exhibits high strength and stiffness. PLA is fully biodegradable and has received great interest. However, the inherent brittleness of PLA largely impedes its wide applications. In this article, the recent progress in PLA toughening using various routes including plasticization, copolymerization, and melt blending with flexible polymers, was reviewed in detail. PLA toughening, particularly modification of impact toughness through melt blending, was emphasized in this review. Reactive blending was shown to be especially effective in achieving high impact strength. The relationship between composition, morphology, and mechanical properties were summarized. Toughening mechanisms were also discussed. © 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2011.
Co-reporter:Bo Liu;Linshu Liu
Journal of Polymers and the Environment 2011 Volume 19( Issue 3) pp:
Publication Date(Web):2011 September
DOI:10.1007/s10924-011-0322-4
Sugar beet pulp (SBP), the residue from sugar extraction, was compounded and turned into in situ thermoplastic composite materials. The compounding was performed using a common twin- screw compounding extruder and water and glycerol were used as co-plasticizers. The melt compounding of SBP utilized the water-soluble characteristics of pectin which is one of main components of SBP. The structure of SBP was destroyed under extrusion and pectin was partially released and plasticized by water and glycerol. Scanning electron microscopy revealed that the cellulose microfibrils were dispersed in the matrix of pectin and other ingredients. Effects of the water and glycerol co-plasticizers on rheological, tensile and dynamic mechanical properties of the SBP plastics were investigated. Effects of relative humidity of the environment on the tensile and dynamical mechanical properties of the neat SBP compounds were also evaluated. The results demonstrated that SBP could be processed as a plastic with water and glycerol as co-plasticizers using traditional processing equipments.
Co-reporter:Feng Chen and Jinwen Zhang
ACS Applied Materials & Interfaces 2010 Volume 2(Issue 11) pp:3324
Publication Date(Web):October 21, 2010
DOI:10.1021/am100751c
In this study, soy protein concentrate (SPC) was used as a plastic component to blend with poly(butylene adipate-co-terephthalate) (PBAT). Effects of SPC plasticization and blend composition on its deformation during mixing were studied in detail. Influence of using water as the major plasticizer and glycerol as the co-plasticizer on the deformation of the SPC phase during mixing was explored. The effect of shear stress, as affected by SPC loading level, on the phase structure of SPC in the blends was also investigated. Quantitative analysis of the aspect ratio of SPC particles was conducted by using ImageJ software, and an empirical model predicting the formation of percolated structure was applied. The experimental results and the model prediction showed a fairly good agreement. The experimental results and statistic analysis suggest that both SPC loading level and its water content prior to compounding had significant influences on development of the SPC phase structure and were correlated in determining the morphological structures of the resulting blends. Consequently, physical and mechanical properties of the blends greatly depended on the phase morphology and PBAT/SPC ratio of the blends.Keywords: bioplastics; percolation; soy protein blend
Co-reporter:Long Jiang, Feng Chen, Jun Qian, Jijun Huang, Michael Wolcott, Linshu Liu and Jinwen Zhang
Industrial & Engineering Chemistry Research 2010 Volume 49(Issue 2) pp:572-577
Publication Date(Web):December 2, 2009
DOI:10.1021/ie900953z
In this work, poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV)/bamboo pulp fiber composites were melt-compounded and injection-molded. Tensile, impact and dynamic mechanical properties of the composites were studied. In contrast to many other short natural fiber reinforced biocomposites which demonstrate decreased strain-at-break, impact toughness and tensile strength, the PHBV/bamboo pulp fiber composites displayed increased tensile strength and impact toughness, and maintained/increased strain-at-break. Microscopic study of the fracture surfaces revealed extensive fiber pullout in both tensile and impact tests. The fiber pullout suggests insufficient interfacial adhesion between the fiber and the matrix. The pullout process in the impact testing dissipated a significant amount of energy and hence substantially improved the impact toughness of the composites. With the improved interfacial adhesion provided by coupling agent polymeric diphenylmethane diisocyanate (pMDI), the strength and modulus of the composites were further increased. However, the toughness was decreased due to the inhibition of the fiber pullout. An acoustic emission test revealed a significantly different process of structural change for the composites with/without pMDI during tension test.
Co-reporter:Bo Liu;Long Jiang;Hongzhi Liu;Lili Sun
Macromolecular Materials and Engineering 2010 Volume 295( Issue 2) pp:123-129
Publication Date(Web):
DOI:10.1002/mame.200900224
Co-reporter:Bo Liu, Long Jiang, Hongzhi Liu and Jinwen Zhang
Industrial & Engineering Chemistry Research 2010 Volume 49(Issue 14) pp:6399-6406
Publication Date(Web):June 24, 2010
DOI:10.1021/ie100218t
In this work, biobased poly(lactic acid) (PLA)/soy protein concentrate (SPC) composites were prepared by twin screw extrusion and injection molding. Poly(2-ethyl-2-oxazoline) (PEOX) and polymeric methylene diphenyl diisocyanate (pMDI) were used sequentially as compatibilization agents to improve phase morphology and interfacial bonding. Properties of the PLA/SPC composites were significantly improved by the application of PEOX and pMDI. The SPC phase was refined and stretched into fine threads during processing under the compatibilization effect of PEOX. With only 0.5 part pMDI, the tensile strength of PLA/SPC composite increased significantly to approach that of pure PLA. With 1 part pMDI, the tensile strength was 6% higher than that of the neat PLA. Scanning electron micrographs evidenced enhanced interfacial adhesion between the two phases. Dynamic mechanical analysis tests revealed that the presence of pMDI enhanced the storage modulus of the composite, especially at temperatures above the glass-transition temperature of PLA, due to the strong interactions between the PLA and SPC phases after pMDI compatibilization. The compatibilized PLA/SPC blends also exhibited significantly reduced water uptakes. Fourier Transform Infrared Spectroscopy confirmed the occurrence of PLA grafting onto SPC molecules through pMDI compatibilization.
Co-reporter:Xiaoqing Liu
Polymer International 2010 Volume 59( Issue 5) pp:607-609
Publication Date(Web):
DOI:10.1002/pi.2781
Abstract
Great achievements have been made in the research of biobased thermoplastic polymers, but the progress concerning thermosetting resins has been minor. In particular, research on high-performance thermosetting polymers from renewable feedstock has not been reported elsewhere. A novel biobased epoxy was synthesized from a rosin acid. Its chemical structure was confirmed using 1H NMR, 13C NMR and Fourier transform infrared spectroscopy. The results indicated that the rosin-based epoxy possessed high glass transition temperature (Tg = 153.8 °C), high storage modulus at room temperature (G′ = 2.4 GPa) and good thermal stability. A rosin-based epoxy with excellent properties was achieved. The results suggest it is possible to develop high-performance thermosetting resins from renewable resources. Copyright © 2010 Society of Chemical Industry
Co-reporter:Feng Chen, Jinwen Zhang
Polymer 2010 Volume 51(Issue 8) pp:1812-1819
Publication Date(Web):6 April 2010
DOI:10.1016/j.polymer.2010.02.035
In this study, soy protein concentrate (SPC) was blended as plastic with poly(butylene adipate-co-terephthalate) (PBAT). An extra amount of water was added to SPC prior to compounding to ensure that SPC behaved like a plastic during mixing. Because of the extensive crosslinking and agglomeration during compounding and the fact that most water was evaporated after drying the compounds, the SPC phase was not able to flow like a plastic in the subsequent processing. Therefore, the compounds became in-situ formed composites. The effects of SPC content and compatibilizer on the morphological, rheological, tensile and dynamic mechanical properties of PBAT/SPC blends were studied. Using maleic anhydride grafted PBAT as compatibilizer resulted in fine domain sizes and good dispersion of SPC and hence improved tensile and dynamic mechanical properties. In the presence of compatiblizer, the formation of percolated SPC network structure was observed at high SPC concentrations, subsequently, resulted in drastic changes in rheological properties, mechanical and dynamic mechanical properties of the blends.
Co-reporter:Hongzhi Liu, Feng Chen, Bo Liu, Greg Estep and Jinwen Zhang
Macromolecules 2010 Volume 43(Issue 14) pp:6058-6066
Publication Date(Web):June 30, 2010
DOI:10.1021/ma101108g
In this study, a poly(lactic acid) (PLA) ternary blend system consisting of PLA, an epoxy-containing elastomer, and a zinc ionomer was introduced and studied in detail. Transmission electron microscopy revealed that the “salami”-like phase structure was formed in the ternary blends. While increase in blending temperature had little effects on the tensile properties of the resulting blends, it greatly changed the impact strength. For the blends prepared at 240 °C by extrusion blending, the resulting PLA ternary blends displayed supertoughness with moderate levels of strength and modulus. It was found that the zinc ions catalyzed the cross-linking of epoxy-containing elastomer and also promoted the reactive compatibilization at the interface of PLA and the elastomer. Both blending temperature and elastomer/ionomer ratio were found to play important roles in achieving supertoughness of the blends. The significant increase in notched impact strength was attributed to the effective interfacial compatibilization at elevated blending temperatures.
Co-reporter:Xiaoqing Liu, Wenbo Xin and Jinwen Zhang
Green Chemistry 2009 vol. 11(Issue 7) pp:1018-1025
Publication Date(Web):17 Apr 2009
DOI:10.1039/B903955D
In this paper, two bio-based epoxy curing agents were synthesized using rosin acids. The chemical structures of the rosin derivatives were confirmed in detail by 1H NMR, 13C NMR, FT-IR and ESI-MS. The synthesis methods of the rosin-based curing agents, curing behaviors and properties of the cured epoxy resins were studied. Two commercial curing agents, which have similar functionality and structural resemblance to the rosin-based curing agents, were also used in the study for comparison. Compared with the synthesis of petrochemical curing agents, the synthesis of rosin-based curing agents was simpler and more environmentally friendly, and has less strict requirements on reactors and catalysts. Non-isothermal curing of a commercial liquid epoxy was studied using differential scanning calorimetry (DSC). The thermal mechanical properties and thermal stability of the cured epoxy resins were evaluated using dynamic mechanical analysis (DMA) and thermogravimetric analysis (TGA), respectively. Results showed that the curing behaviors of the rosin-based curing agents were similar to those of the commercial curing agents. The epoxies cured by rosin-based curing agents also demonstrated similar thermal mechanical properties and thermal stability to the epoxies cured by commercial curing agent analogs.
Co-reporter:Long Jiang, Bo Liu and Jinwen Zhang
Industrial & Engineering Chemistry Research 2009 Volume 48(Issue 16) pp:7594
Publication Date(Web):July 23, 2009
DOI:10.1021/ie900576f
Poly(lactic acid) (PLA) can be toughened by flexible poly(butylene adipate-co-terephthalate) (PBAT) at the cost of a certain degree of strength and modulus loss. In an attempt to achieve balanced overall properties, PLA ternary composites containing both PBAT and rigid nanoparticles, i.e., montmorillonite clay (MMT) or nanosized precipitated calcium carbonate (NPCC), were prepared by twin screw extrusion and subsequent injection molding. Mechanical testing demonstrated that the composites containing MMT exhibited higher tensile strength and modulus but lower elongation compared to the composites containing NPCC. Using maleic anhydride (MA) grafted PLA as a compatibilizer, the elongation of the ternary composites was substantially increased, possibly due to improved dispersion of the nanoparticles. The injection molded ternary composites were shown to have a skin−core layered structure. The skin and core layers were found to possess different microstructure, thermal behavior, and mechanical properties. The microstructure difference led to a sequential fracture behavior during tension testing: the fracture of the core layer was followed by the skin layer. The skin layer, with a higher degree of PLA chain alignment and conformational ordering than the core layer, exhibited a higher glass transition temperature, lower cold crystallization temperature, and a higher degree of perfection in crystalline structures.
Co-reporter:Long Jiang;Bo Liu
Macromolecular Materials and Engineering 2009 Volume 294( Issue 5) pp:301-305
Publication Date(Web):
DOI:10.1002/mame.200900018
Co-reporter:Honghua Wang;Xiaoqing Liu;Bo Liu;Ming Xian
Polymer International 2009 Volume 58( Issue 12) pp:1435-1441
Publication Date(Web):
DOI:10.1002/pi.2680
Abstract
BACKGROUND: Although rosin acid derivatives have received attention in polymer synthesis in recent years, to the best of our knowledge, they have rarely been employed as epoxy curing agents. The objective of the study reported here was to synthesize rosin-based flexible anhydride-type curing agents and demonstrate that the flexibility of a cured epoxy resin can be manipulated by selection of rosin-based anhydride-type curing agents with appropriate molecular rigidity/flexibility.
RESULTS: Maleopimarate-terminated low molecular weight polycaprolactones (PCLs) were synthesized and studied as anhydride-type curing agents for epoxy curing. The chemical structures of the products were confirmed using 1H NMR spectroscopy and Fourier transform infrared spectroscopy. Mechanical and thermal properties of the cured epoxy resins were studied. The results indicate that both the epoxy/anhydride equivalent ratio and the molecular weight of PCL diol play important roles in the properties of cured resins.
CONCLUSION: Rosin-based anhydride-terminated polyesters could be used as bio-based epoxy curing agents. A broad spectrum of mechanical and thermal properties of the cured epoxy resins can be obtained by varying the molecular length of the polyester segment and the epoxy/curing agent ratio. Copyright © 2009 Society of Chemical Industry
Co-reporter:Feng Chen, Jinwen Zhang
Polymer 2009 50(15) pp: 3770-3777
Publication Date(Web):
DOI:10.1016/j.polymer.2009.06.004
Co-reporter:Feng Chen, LinShu Liu, Peter H. Cooke, Kevin B. Hicks and Jinwen Zhang
Industrial & Engineering Chemistry Research 2008 Volume 47(Issue 22) pp:8667-8675
Publication Date(Web):October 28, 2008
DOI:10.1021/ie800930j
Sugar beet pulp (SBP), the residue from the sugar extraction process, contains abundant dietary fibers and is mainly used for feedstuff. In this study, poly(lactic acid) (PLA) and SBP composites were prepared using a twin screw extruder. The phase structure, thermal properties, mechanical properties, and water absorption of the composites were studied. The molecular weight change of PLA in the composites was also studied. Polymeric diphenylmethane diisocyanate (pMDI) was used as a coupling agent and resulted in significant increases in mechanical properties and water resistance. The tensile strength of the PLA/SBP (70/30 w/w) composite was only 56.9% that of neat PLA, but it was increased to 80.3% with the addition of 0.5% pMDI and further increased to 93.8% at 2% pMDI. With 50% SBP and 2% pMDI, the tensile strength of the composite was 87.8% of that of neat PLA. The microstructure of the composites indicated that the addition of pMDI greatly improved the wettability of the SBP particles by PLA and increased the penetration of PLA into the porous SBP. Consequently, the failure of the composites in mechanical testing changed from extensive debonding without pMDI to progressive rupture of the SBP particles with pMDI.
Co-reporter:Long Jiang;Jijun Huang;Jun Qian;Feng Chen
Journal of Polymers and the Environment 2008 Volume 16( Issue 2) pp:83-93
Publication Date(Web):2008 April
DOI:10.1007/s10924-008-0086-7
In this study, poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV)/bamboo pulp fiber (BPF) composites were prepared by melt compounding and injection molding. The crystallization ability, tensile strength and modulus, flexural strength and modulus, and impact strength were found substantially increased by the addition of BPF. Tensile and flexural elongations were also moderately increased at low fiber contents (<20%). BPF demonstrated not only higher strength and modulus, but also higher failure strain than the PHBV8 matrix. Boron nitride (BN) was also investigated as a nucleation agent for PHBV8 and maleic anhydride grafted PHBV8 (MA-PHBV8) as a compatibilizer for the composite system. BN was found to increase the overall properties of the neat polymer and the composites due to refined crystalline structures. MA-PHBV8 improved polymer/fiber interactions and therefore resulted in increased strength and modulus. However, the toughness of the composites was substantially reduced due to the hindrance to fiber pullout, a major energy dissipation source during the composite deformation.
Co-reporter:Long Jiang;Michael P. Wolcott;Karl Englund
Polymer Engineering & Science 2007 Volume 47(Issue 3) pp:281-288
Publication Date(Web):6 FEB 2007
DOI:10.1002/pen.20705
Decking and railing is the largest and fastest growing market for wood–plastic composites (WPCs). Despite WPC's advantages in comparison to lumber, its modulus and creep resistance need to be further improved for demanding structural applications. In this study, WPC deck boards were reinforced by the composite sheets made of commingled glass and polypropylene fiber. Various reinforcement arrangements were carried out to identify the optimal one. Scanning electron microscopy revealed good bonding at the reinforcement/WPC interface. All reinforced samples exhibited considerably increased modulus of rupture, modulus of elasticity, and strain at break. The creep resistance of the reinforced WPC boards was also greatly improved. Creep strain was simulated with Findley's model. Master curves of creep compliance were generated by time–temperature–stress superposition principle. The Prony series was found to be the analytical expression of the master curves with acceptable accuracy. With improved mechanical properties, the reinforced WPC board can be used in more demanding applications. POLYM. ENG. SCI., 47:281–288, 2007. © 2007 Society of Plastics Engineers.
Co-reporter:Linyong Zhu;Jun Qian;Robert S. Whitehouse
Journal of Polymer Science Part B: Polymer Physics 2007 Volume 45(Issue 13) pp:1564-1577
Publication Date(Web):22 MAY 2007
DOI:10.1002/polb.21157
In this study, thymine and melamine were introduced as nucleating agents for poly(3-hydroxybutyrate-co-3-hydroxyvalerates) (PHBVs) and poly(3-hydroxybutyrate) (PHB), and their effects were compared with that of boron nitride (BN). Because the overall crystallization rate of PHBVs decreases significantly with the increase in the 3-hydroxyvalerate comonomer content, the study focused on the crystallization of PHBVs. Isothermal crystallization kinetics of the neat PHBVs and the nucleated PHBVs were studied by differential scanning calorimetry (DSC). The Avrami equation was derived and the parameters were assessed for the nucleation and crystal growth mechanism. The nucleation and crystal growth were examined using polarized optical microscopy. All nucleating agents had similar particle sizes and showed good dispersion in the polymer matrix, as revealed by scanning electron microscopy. The results indicated that BN and thymine significantly increased the overall crystallization rate for all PHBVs studied and demonstrated very similar nucleating effects. Melamine reacted with PHBVs and accelerated the thermal degradation, and hence was less effective in nucleating PHBVs. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 1564–1577, 2007
Co-reporter:Yu Fu, Jinwen Zhang, Hang Liu, William C. Hiscox and Yi Gu
Journal of Materials Chemistry A 2013 - vol. 1(Issue 7) pp:NaN2674-2674
Publication Date(Web):2012/12/11
DOI:10.1039/C2TA00353H
A novel one-step approach for the pH-triggered electrochemically interacted exfoliation of graphene sheets in graphite oxide and simultaneous reduction and functionalization with the aid of the ionic liquid is reported. The developed method shows significant advantages over the conventional functionalized/chemically reduced graphene. Particularly, for the first time, no additional stabilizer or modifier is needed to stabilize the resulting processible graphene dispersion. The prepared graphene oxide and its functionalized graphene are characterized by SEM, TEM, FTIR, UV-vis, XRD, Raman, XPS, and NMR. The results indicate that, with the aid of the IL during the reaction, the resulting functionalized graphene shows improved organophilicity, good wettability and improved interfacial interactions as well as significant resistance to thermal degradation. The methodology paves a new way for use of the IL as a processing aid and reaction medium to promote chemical functionalization of graphene through the electrochemically interacted exfoliation of graphene sheets and can be expected to provide a new approach with great promise for its organophilic wettability and enhanced interfacial adhesion as well as improved thermal stability. Furthermore, the controlled modifications of graphene nanoreinforcements can also be expected to alter the nature of the interactions between components.
.jpg)
![2(3H)-Furanone,dihydro-4-[(S)-hydroxy(4-hydroxy-3-methoxyphenyl)methyl]-3-[(4-hydroxy-3-methoxyphenyl)methyl]-,(3R,4R)-](http://img.cochemist.com/ccimg/20300/20268-71-7.png)
![2(3H)-Furanone,dihydro-4-[(S)-hydroxy(4-hydroxy-3-methoxyphenyl)methyl]-3-[(4-hydroxy-3-methoxyphenyl)methyl]-,(3R,4R)-](http://img.cochemist.com/ccimg/20300/20268-71-7_b.png)
![(3s,3ar,6r,6ar)-3,6-bis(prop-2-enoxy)-2,3,3a,5,6,6a-hexahydrofuro[3,2-b]furan](http://img.cochemist.com/ccimg/6400/6338-34-7.png)
![(3s,3ar,6r,6ar)-3,6-bis(prop-2-enoxy)-2,3,3a,5,6,6a-hexahydrofuro[3,2-b]furan](http://img.cochemist.com/ccimg/6400/6338-34-7_b.png)