Co-reporter:Chunhai Li, Shanshan Luo, Jianfeng Wang, Hong Wu, Shaoyun Guo, and Xi Zhang
Biomacromolecules April 10, 2017 Volume 18(Issue 4) pp:1440-1440
Publication Date(Web):March 16, 2017
DOI:10.1021/acs.biomac.7b00367
Self-assembly nucleators have been increasingly used to manipulate the crystallization of PLLA due to their strong intermolecular interaction with PLLA, while the molecular mechanism of such interaction is still unrevealed. In present work, one special self-assembly nucleator (TMC-300) with relatively high solubility in PLLA matrix, is chosen to investigate how the interaction works at molecular level to promote the crystallization of PLLA mainly through time-resolved spectroscopy. The results indicate that due to the dipole–dipole NH···O═C interaction between dissolved TMC-300 and PLLA, PLLA chains are transformed into gt conformer before TMC-300 phase-separating from PLLA melt, resulting in low energy barrier to pass for the following formation of PLLA α-crystal (α-crystal is consisted of gt conformer). Once the dissolved TMC-300 starts to self-assemble into frameworks upon cooling, the transformed PLLA chains with high population of gt conformer form the primary nuclei on the surface of such self-assembling TMC-300 frameworks. For the first time, not only the heterogeneous nucleation but also the conformational regulation of PLLA chains are proved to be responsible for the high efficiency of the self-assembly nucleators (TMC-300) in promoting the crystallization of PLLA. Therefore, conformational regulation is proposed for crystalline manipulation of PLLA, and this work brings new insight on promoting the crystallization of PLLA even other polymers by regulating their molecular conformation.
Co-reporter:Jianfeng Wang, Chunhai Li, Xiaomeng Zhang, Lichao Xia, Xianlong Zhang, Hong Wu, Shaoyun Guo
Chemical Engineering Journal 2017 Volume 325(Volume 325) pp:
Publication Date(Web):1 October 2017
DOI:10.1016/j.cej.2017.05.090
•Reduced graphene oxide (RGO) was melt-processed into polycarbonate (PC).•RGO can enhance the toughness, strength and notch resistance of PC greatly.•The toughening mechanism was investigated.•Microcrack, crack pinning, deflection and arresting were the toughening mechanism.The toughening effect of graphene sheets on polycarbonate (PC) was investigated to fabricate PC composites with excellent balanced toughness, notch resistance as well as strength. The reduced graphene oxide (RGO) was incorporated into PC matrix through melt compounding. A maximum toughening effect was observed in PC/RGO (PCG) composites with 0.03 wt% or 0.07 wt% RGO. Particularly, the tensile fracture toughness of PCG composites with 0.03 wt% RGO was enhanced by 89%. The notched impact strength and KIC of PCG composite with 0.07 wt% RGO was increased by 46% and 58%, respectively. The point of 0.1 wt% was found to be the ductile-brittle transition point in PCG composites. Meanwhile, the yield strength of these novel materials was increased by around 12% as well at loading of 0.07 wt%. Microcrack, resulting from interfacial debonding between PC and RGO as well as breakage and pulling out of graphene layer, was proposed to be the main toughening mechanism contributing to the great enhanced fracture toughness and notch resistance. Apart from the microcrack, crack pinning, crack deflection and crack arresting were also found and proposed to be toughening mechanism in notch-fractured process. This work not only provides us a novel strategy to fabricate advanced PC nanocomposites but also gives us a deep understanding on the toughening role of graphene on polymers.Download high-res image (143KB)Download full-size image
Co-reporter:Xiaomeng Zhang, Jiajia Zhang, Chunhai Li, Jianfeng Wang, Lichao Xia, Fang Xu, Xianlong Zhang, Hong Wu, Shaoyun Guo
Chemical Engineering Journal 2017 Volume 328(Volume 328) pp:
Publication Date(Web):15 November 2017
DOI:10.1016/j.cej.2017.07.087
•The alternating multilayered composites with 2 to 32 layers were obtained.•The multilayered structure was constructed through the melt extrusion method.•The contradiction between antistatic property and electrical insulation was resolved.•Thermally conductive enhancement mechanism of structure was in-depth investigated.To fabricate thermally conductive while electrically insulating composites with excellent antistatic property is a huge challenge in the region of packaging materials of electronic devices due to the contradiction between the electrical insulation and the antistatic property. In the present work, the peculiar multilayer structures with alternating high efficiency thermally, electrically conductive layers and thermally conductive, electrically insulating layers were constructed successfully through a simple, one-step melt extrusion method. Such thermally conductive and electrically insulating composites possessed significant anisotropic electrical resistivity; for example, the in-plane electrical resistivities (parallel to the layer direction) were below 117 Ω × cm, while the through-plane electrical resistivities were over 5 × 1013 Ω × cm. Meanwhile, with increasing the layer number, thermal conductivity of the composite with the same filler loading was improved monotonously, and reached as high as 1.45 W/(m × K) in the composite with 32 layers. In addition, tensile strength and elongation at break of the composites were also enhanced due to the different deformation mechanisms of separate layers. Furthermore, to give a deep insight into the enhancement mechanism of thermally conductive property, finite element analysis was applied and the results indicated that high efficiency thermally, electrically conductive layers possessed magnified effects on the heat dissipation. Therefore, the multilayer structure with alternating high efficiency thermally, electrically conductive layers and thermally conductive, electrically insulating layers can endow the composite with excellent comprehensive properties effectively, and it also sheds light on the design and fabrication of high performance materials for the applications of thermal management or other energy harvesting fields.Download high-res image (265KB)Download full-size image
Co-reporter:Xiaomeng Zhang, Jiajia Zhang, Xianlong Zhang, Chunhai Li, Jianfeng Wang, Huan Li, Lichao Xia, Hong Wu, Shaoyun Guo
Composites Science and Technology 2017 Volume 150(Volume 150) pp:
Publication Date(Web):29 September 2017
DOI:10.1016/j.compscitech.2017.07.019
The heat dissipation property of the thermally conductive and electrically insulating composites can be enhanced by constructing high efficiency thermally conductive pathways, while the mechanical properties of the final composites are always neglected. In this work, graphite (Gt), a typical carbon based filler with excellent thermal conductivity, was highly oriented and uniformly dispersed in polymer matrix to keep the electrical resistivity of the composite at a high level, even when the content of Gt was 33 wt%. Then, in order to further improve thermal conductivity, the consecutive and high efficiency thermally conductive yet electrically insulating pathways were constructed by adding silicon carbide (SiC) particles into the composites as junctions to release the thermally conductive potential of Gt via forming phonon transport channels. As a result, thermal conductivity reached 1.68 W/(m × K) when the content of SiC was 20 wt%. Meanwhile, the in-plane thermal conductivity (along the melt flow direction) was as high as 3.8 W/(m × K), which was over 5-fold larger than the through-plane thermal conductivity (along the thickness direction). Subsequently, Agari model and thermally conductive simulation based on the finite element analysis were also applied to give a deep insight into the effect of this special filler architecture on the heat dissipation performance of the composites. Furthermore, mechanical properties of such composites were also largely enhanced. Therefore, building up high efficiency thermally conductive and electrically insulating pathways through highly oriented and uniformly dispersed 1-D or 2-D anisotropic carbon based fillers close-packed with another kind of uniformly dispersed thermally conductive and electrically insulating fillers is a simple and effective method to endow the composites with excellent thermal conductivity, high electrical resistivity and great mechanical properties simultaneously.
Co-reporter:Jianfeng Wang, Xiuxiu Jin, Hong Wu, Shaoyun Guo
Carbon 2017 Volume 123(Volume 123) pp:
Publication Date(Web):1 October 2017
DOI:10.1016/j.carbon.2017.07.055
The poor dispersion of graphene-based materials and the weak interfacial interaction between the nanofillers and polymer matrix greatly limit the reinforcing efficiency of graphene-based nanofillers on polymers. Moreover, the polymers reinforced with graphene usually tend to be brittle. In this paper, hybrid GO/CNT nanostructure was designed and cross-linked through amide bond, which can disperse and embed into the PI matrix commendably, providing strong interfacial interaction between the nanofillers and the PI matrix. Compared with neat PI, the amide bond hybrid GO/CNT (1.1 wt % in total) can endow the PI matrix with a dramatic increment on strength (118%), modulus (94%), fracture toughness (138%) and electrical conductivity (11 orders), due to the effective stress transfer at the interface between PI matrix and nanofillers as well as at the interface between GO and CNT. Furthermore, the over-all performance of the nanocomposites containing chemical amide bond hybrid GO/CNT is superior to those containing hydrogen bond hybrid GO/CNT and π-π stack hybrid GO/CNT, providing us with a framework to study the interfacial interactions (covalent bond, hydrogen bond and π-π stack) in hybrid GO/CNT nanomaterials and their influence on the performance of polymer nanocomposites.Download high-res image (289KB)Download full-size image
Co-reporter:Xianlong Zhang, Mingtao Yang, Xiaomeng Zhang, Hong Wu, Shaoyun Guo, Yuzhong Wang
Composites Science and Technology 2017 Volume 150(Volume 150) pp:
Publication Date(Web):29 September 2017
DOI:10.1016/j.compscitech.2017.06.007
Neutron radiation is often encountered in a wide range of industries, such as aerospace, healthcare and nuclear power plants. It has been an arduous challenge to shield this neutron radiation to improve equipment safety and protect human health. In order to make an effective neutron shielding material, alternating multi-layered composites (high density polyethylene)/(high density polyethylene/boron nitride), (HDPE/(HDPE/BN)) and (HDPE/BN)/(HDPE/Barium sulfate (BaSO4)) were fabricated using a multi-layered co-extrusion system. The HDPE/BN layers in the alternating multilayered HDPE/(HDPE/BN) and (HDPE/BN)/(HDPE/BaSO4) composites had a continuous and layered distribution in their structure, with the BN particles oriented in the extrusion direction. The probability of collision between incident photons and flake-shaped particles is enhanced through alignment of the oriented BN particles. In this way, neutron transmittance noticeably decreased with an increasing number of layers. Compared to traditional polymer-blended materials, the alternating multilayered composites showed excellent shielding efficiency. In addition, the results of the dynamic rheological analysis showed that alternating multi-layered composites with more layers can weaken the cross-linking effects induced by secondary radiation. Furthermore, according to the Nano-TA analysis, BaSO4 was an effective shield of secondary radiation, so the average melting point, in nanoscale, can be represented as follows: (Nano-Tm¯) ((HDPE/BN)/(HDPE/BaSO4))> Nano-Tm¯ (HDPE/(HDPE/BN)).
Co-reporter:Xianlong Zhang, Xiaomeng Zhang, Mingtao Yang, Shuo Yang, Hong Wu, Shaoyun Guo, Yuzhong Wang
Composites Science and Technology 2016 Volume 136() pp:104-110
Publication Date(Web):18 November 2016
DOI:10.1016/j.compscitech.2016.10.008
To simultaneously resolve an undesirable electromagnetic wave and heat emissions that were caused by an electronic device, an electromagnetic interference (EMI) shielding material with excellent electrical insulation and high thermal conductivity was urgently required. However, keeping the EMI shielding material on electrical insulation still remained a challenge due to the superior electrical conductive network in it. We fabricated an ordered multilayer film through casting layer (graphene oxide/poly(-hydroxybenzate-co-DOPO-benzenediol dihydrodiphenyl ether terephthalate)) by layer (boron nitride/(maleated styrene-ethylene/butylene-styrene)), and the special architecture of the film not only simultaneously built the superior electrical and thermal conductive network in-plane direction, but also effectively blocked the electrical conductive path through-plane direction. Moreover, the ordered multilayer film (11 layers) exhibited a good EMI shielding effectiveness (37.92 dB), excellent electrical insulation (breakdown strength was 1.52 MV/m) and high thermal conductivity (12.62 W/mK) in-plane direction, indicating that the ordered multilayer film was a novel promising candidate for an ideal EMI shielding material with excellent electrical insulation and high thermal conductivity in today's electronic devices.The ordered multilayer film simultaneously has superior electromagnetic interference shielding effectiveness, excellent electrical insulation and high thermal conductivity.
Co-reporter:Jianfeng Wang, Hong Wu and Shaoyun Guo
RSC Advances 2016 vol. 6(Issue 2) pp:1313-1323
Publication Date(Web):18 Dec 2015
DOI:10.1039/C5RA24758F
In this work, an advanced extrusion approach (MSEDC technique) was adopted to control crystalline structure and phase morphology in PP/POE blends. The results showed that PP matrix alternating shish-kebab crystalline structure with spherulites, and POE phase alternating micro-/nano-sheets with nano-fibrils and elongated spherical particles were introduced into PP/POE blends simultaneously. The as-obtained densely-stacked shish-kebab crystalline structure of the PP matrix can provide blends with greatly enhanced tensile yield strength, while the planar POE phase with micro-/nano-sheets can induce the deflection of crack, providing the blends with greatly increased toughness. Moreover, hierarchical interfacial entanglement, formed between PP molecules and POE molecules, can connect the matrix and dispersed phase effectively, which is helpful to obtain materials with simultaneously enhanced strength and toughness. Compared with neat PP, the notched impact strength and tensile yield strength of MSEDC PP/POE blends is enhanced 490% and 35%, respectively, which is the first report realizing simultaneous reinforcement and toughening in polypropylene based on a polypropylene/elastomer binary system.
Co-reporter:Lichao Xia, Min Wang, Hong Wu, Shaoyun Guo
International Journal of Hydrogen Energy 2016 Volume 41(Issue 4) pp:2887-2895
Publication Date(Web):30 January 2016
DOI:10.1016/j.ijhydene.2015.12.043
•FKM gaskets with different ingredients are chemical aged in simulated PEMFC solution.•Effects of cure system and filler on chemical aging behavior are investigated.•FKM recipe that shows good chemical stability is optimized.•The insert filler BaSO4 reduces the blister but deteriorates the chemical stability of the gaskets.The chemical aging behavior of gaskets especially the chemical stability is crucial to the overall performance of PEMFC stack. The chemical stability of gaskets not only depends on the polymer but also heavily depends on the other ingredients. In this paper, we have studied the properties of fluoroelastomer with different amount of the cure agent, acid-acceptor and filler in the simulated PEMFC environment. The weight and volume change of samples was monitored. The surface conditions of the virgin and aged samples were observed using optical microscopy. Leachants in the soaking solution were detected using atomic emission spectrometry. ATR-FTIR was employed to determine the chemical change of samples. These results show that FKM cured with bisphenol system has the best comprehensive properties when the amount of bisphenol AF is set as 2.5 phr and the amount of Ca(OH)2 is 6 phr. The inert filler BaSO4 is not suitable for FKM because it has inferior effect on the compression resistance and chemical stability of FKM in this system.
Co-reporter:Lichao Xia, Hong Wu, Shaoyun Guo, Xiaojie Sun, Wenbin Liang
Composites Part A: Applied Science and Manufacturing 2016 Volume 81() pp:225-233
Publication Date(Web):February 2016
DOI:10.1016/j.compositesa.2015.11.023
In this work, the composites with multilayered distribution of the mica were fabricated by a multilayer coextrusion technique. The influence of layer number on sound insulation and mechanical properties of multilayered composites was investigated. The distribution, dispersion and orientation of mica particulates in composites were characterized by PLM and SEM. The sound insulation property of composites was measured by four microphone impedance tube. PLM and SEM images showed that the mica was distributed as the multilayered structure along the thickness direction of the composites. With the increase of layer number, more mica aggregates delaminated into thin flakes and aligned parallel to the flow direction. Compared to the conventional composites, the multilayered composites showed the enhanced sound insulation efficiency and mechanical properties. The discontinuity of sound impedance and the improved stiffness were considered to play a crucial role in the improvement of sound transmission loss.
Co-reporter:Fan Lei, Huaning Yu, Shuo Yang, Huimin Sun, Jiang Li, Shaoyun Guo, Hong Wu, Jiabin Shen, Rong Chen, Ying Xiong
Polymer 2016 Volume 82() pp:274-284
Publication Date(Web):15 January 2016
DOI:10.1016/j.polymer.2015.11.053
•The content of β-crystal in neat iPP was enhanced with increasing number of (LME).•The content of β-crystal in OMMT/iPP composites was decreased with increasing number of LME.•The dispersion of OMMT in iPP matrix was improved by increasing shear force.•The dimensions of OMMT particles influenced the morphology of iPP crystal.•A schematic was proposed to describe the formation mechanism of α-crystal and β-crystal.In this work, the different effects of organic montmorillonite (OMMT) particles and shear flow on the crystallization behavior of isotactic polypropylene (iPP) were discussed. While neat iPP and OMMT filled iPP were treated using the multistage stretching extrusion technology, changing the number of laminating-multiplying elements (LMEs) can obtain samples with different dispersion degree of OMMT particles and different orientation degree of molecular chains. With the increase of LME number, the content of β-crystal in neat iPP increased. But for OMMT/iPP composites, decreasing LME number caused the increase of content of β-crystal. The experimental results showed that the shear flow and large OMMT aggregations were essential factors for the formation of β-crystal in composites, and the crystalline morphology strongly depended on the size of OMMT particles. The scanning electron microscope (SEM) images of sample with 3 wt% of OMMT particles and without LME illustrated that β-transcrystallinity, fan-shaped β-crystal and α-spherulite were induced by different size of OMMT particles, respectively. A schematic was proposed to describe the formation mechanism of α-crystal and β-crystal under the coexistence of OMMT particles and shear flow.
Co-reporter:Kangming Xu, Fengshun Zhang, Xianlong Zhang, Jiwei Guo, Hong Wu and Shaoyun Guo
RSC Advances 2015 vol. 5(Issue 6) pp:4200-4209
Publication Date(Web):28 Nov 2014
DOI:10.1039/C4RA06644H
The fundamental mechanism of the improved damping properties of poly(vinyl acetate) (PVAc), contributed by the introduction of hindered phenols, was systematically elucidated by two-dimensional infrared (2D IR) spectroscopy, dynamic mechanical analysis (DMA), differential scanning calorimeter (DSC), X-ray diffraction (XRD) and molecular dynamics (MD) simulation. The 2D IR results revealed the evolution of hydrogen bonds (H-bonds) from intermolecular H-bonds to H-bond networks of PVAc/hindered phenols. Note that subsequent DMA results revealed that the damping properties of PVAc exhibited two different degrees of improvement due to the addition of hindered phenol. Moreover, DSC results showed that all hybrids were miscible, as concentration fluctuations changed irregularly. In accordance with the XRD observation of only amorphous hindered phenols existing in the PVAc matrix, further MD simulation, based on an amorphous cell, characterized the number of H-bonds, the binding energy and the fractional free volume (FFV) of the hybrids. It was observed that the variation tendency of the simulation data was in accordance with the experimental results. Therefore, the damping mechanism of PVAc/hindered phenol hybrids was proposed through a detailed analysis on the synergistic effect of the number of intermolecular H-bonds and the binding energy between PVAc and the hindered phenol, as well as the FFV or dynamic heterogeneity.
Co-reporter:Xianlong Zhang, Hong Wu, Shaoyun Guo and Yuzhong Wang
RSC Advances 2015 vol. 5(Issue 121) pp:99812-99819
Publication Date(Web):16 Nov 2015
DOI:10.1039/C5RA19982D
In an attempt to correctly understand an extra weak exothermic peak (Th) (near the melting temperature of the polyethylene (PE)) of the PE in the PE/boron nitride (BN) composites, a new hypothesis was proposed and proved: Th was induced by PE crystallization. When the BN content was more than 10 wt%, the Th was observed. Simultaneously, beside the Th, another weak exothermic peak (T1h), was also found. Beside the main melting peak (Tm), an extra melting peak (Tmh) also appeared. The results of the local thermal analysis technique (nano-TA) showed that the local melting temperature (nano-Tm) of the PE near the BN aggregates was higher 4–8 °C than that in other areas, indicating that the meso-phase (meso-phase was also induced by PE crystallization) can be formed near the BN aggregates during the PE crystallization. Moreover, the appearance of the Th and T1h was attributed to the differently nucleated capability of the different BN aggregates in local areas during the PE crystallization. When the annealing time and temperature were 20 min and 130 °C, respectively, the thermal conductivity of the PE/BN composite was 16% higher than that of the unannealed PE/BN composites. In addition, the results of the wide angle X-ray diffraction (WAXD) showed that the BN particles had no influence on the PE crystal form in the PE/BN composites.
Co-reporter:Tianbao Zhao, Mingtao Yang, Hong Wu, Shaoyun Guo, Xiaojie Sun, Wenbin Liang
Materials Letters 2015 Volume 139() pp:275-278
Publication Date(Web):15 January 2015
DOI:10.1016/j.matlet.2014.10.061
•The POE foam/film foaming sheet with alternating multilayered structure was successfully prepared through multilayer co-extrusion system.•This technique provided the new idea to obtain structure–foaming material with high sound absorption.•The foam/film alternating multilayered structure could be improved the sound absorption efficiency due to more reflection and friction loss of sound in layer interface. Meanwhile, the sound absorption efficiency of the foam/film foaming sheet with alternating multilayered structure increased with increasing of layer number.Poly (ethylene-co-octene) foaming materials with alternating multilayered structure were successfully prepared through multilayer co-extrusion. Poly (ethylene-co-octene) was micro-crosslinked and fully cured before and after the foaming process with co-extrusion. The effects of the layer number on foam morphology and density of poly (ethylene-co-octene) foaming materials were investigated. It was found that with increasing the layer number, the cell size was reduced while the density was not obviously changed. Meanwhile, this technique provided the new idea to obtain the poly (ethylene-co-octene) foaming material with excellent sound absorption. The results indicated that the foam/film alternating multilayered structure could improve the sound absorption efficiency of the foaming sheet, which was increased with increasing the layer number and decreasing of cell size.
Co-reporter:Tianbao Zhao;Xianlong Zhang;Shaoyun Guo;Xiaojie Sun;Wenbin Liang
Journal of Applied Polymer Science 2015 Volume 132( Issue 4) pp:
Publication Date(Web):
DOI:10.1002/app.41339
ABSTRACT
In this article, the multilayered foaming sheet with alternate layered structure was successfully prepared through multilayer co-extrusion. The high melt strength polypropylene (HMSPP)/poly (ethylene-co-octene) (POE) blend and POE were designed as foaming layers and film layers, respectively. POE was added into HMSPP to reduce the crystalline degree and improve the processing performance. The rheological results indicated that the addition of POE had a little effect on relaxation process and the strain hardening behavior of HMSPP when the POE content was lower than 50%. The results of the foam morphology showed that the cell size and its distribution of the multilayered foaming sheet with alternate layers were better than that with single layer. In addition, the cell size reduced and the cell density increased with increasing the number of layers from 4 to 32. The mechanical properties of the multilayered foaming sheet with alternate layers also could be improved through assembling of foaming layers and film layers. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41339.
Co-reporter:Fengshun Zhang;Guansong He;Kangming Xu;Shaoyun Guo
Journal of Applied Polymer Science 2015 Volume 132( Issue 2) pp:
Publication Date(Web):
DOI:10.1002/app.41259
ABSTRACT
The alternating multilayered damping composites, which were consisted of chlorinated butyl rubber (CIIR) layers and poly(vinyl chloride) (PVC) layers, were first prepared through multilayered coextrusion technology. The multilayered structure was controlled by adjusting the layer number or the thickness ratio of CIIR layer and PVC layer. The damping and flame-retardant properties of the CIIR/PVC multilayered damping composites were investigated by dynamic mechanical analysis, the limiting oxygen index, and thermogravimetric analyzer, respectively. The results showed that the effective damping temperature range was broadened with increasing the layer number, since multilayered structure resulted in partial overlap of the loss peaks of CIIR and PVC. Meanwhile, the flame-retardant properties of the multilayered composites were also enhanced with increasing the layer number. Less surface area of CIIR contacting oxygen in the confined burning space, rather than the formation of char residue, could effectively retard the combustion of the material. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41259.
Co-reporter:Tianbao Zhao, Mingtao Yang, Hong Wu, Shaoyun Guo, Xiaojie Sun, Wenbin Liang
Materials Letters 2015 Volume 145() pp:363
Publication Date(Web):15 April 2015
DOI:10.1016/j.matlet.2014.12.084
Co-reporter:Shuo Yang, Huaning Yu, Fan Lei, Jiang Li, Shaoyun Guo, Hong Wu, Jiabin Shen, Ying Xiong, and Rong Chen
Macromolecules 2015 Volume 48(Issue 12) pp:3965-3973
Publication Date(Web):June 9, 2015
DOI:10.1021/acs.macromol.5b00396
The β-nucleated polypropylene (β-PP) and polypropylene (PP) were coextruded to form the alternating layered structure with different layer number. During the isothermal crystallization of layered samples at 130 °C, the high-density β-nuclei at the two-dimensional layered interfaces between β-PP and PP layers grew asymmetrically. In the β-PP layer, the growth of β-lamellae was quickly terminated by other β-spherulites. In the PP layer, because the formation of α-crystals delayed, all β-lamellae could freely grow perpendicular to the interface and finally form the β-transcrystallinity (β-TC) layer with about 25 μm thickness. If the thickness of PP layer was lower than 50 μm, PP layer would be almost occupied by β-TC. The ordered arrangement of β-TC led to an orientation of molecular chains of β-TC layer parallel to the interface. With the increase of layer number, the content of β-TC and orientation degree of layered samples increased. This paper provided a simple and effective method to prepare continuous, highly ordered and content-controlled β-TC. As a result, the sample with high content of β-TC exhibited good mechanical properties.
Co-reporter:Chun-hai Li;Jian-feng Wang;Ji-wei Guo 吴宏
Chinese Journal of Polymer Science 2015 Volume 33( Issue 10) pp:1477-1490
Publication Date(Web):2015 October
DOI:10.1007/s10118-015-1692-1
The multilayered polypropylene (PP) and poly(ethylene-co-octene) (POE) sheets were prepared by the micro-layered co-extrusion system. The essential work of fracture (EWF) and the impact tensile methods have been successfully used to evaluate the toughening behaviors of the PP/POE multilayered blends under quasi-static and dynamic uniaxial tensile stress, respectively. The experimental results indicate that the multilayered structure plays a key role in the toughening behaviors. On increasing the layer number of the multilayered blends, the specific essential work of fracture, we, increases obviously. As for the βwp, there is no obvious variation in the multilayered blends with low POE content (6.79%), however, obvious enhancement is observed with increasing the layer number of the high POE content multilayered blends (16.57%). Compared with the conventional blends, the multilayered blends with 6.79% POE content are effective to increase the value of we. Additionally, the multilayered blends with high layer numbers present absolute advantage in improving the impact tensile values.
Co-reporter:Xian-long Zhang 吴宏;Shao-yun Guo 郭少云
Chinese Journal of Polymer Science 2015 Volume 33( Issue 7) pp:988-999
Publication Date(Web):2015 July
DOI:10.1007/s10118-015-1645-8
The molecular structure of SEBS grafted with maleic anhydride (SEBS-g-MAH) through ultrasound initiation was investigated by nuclear magnetic resonance (NMR). It can be confirmed that the grafting groups mainly exist on the terminus of the ultrasound initiated SEBS-g-MAH. However, it was difficult to detailedly confirm the block of the SEBS on which MAH is grafted through characterization of 1H-NMR due to the complex structure of the SEBS. Moreover, the temperature-dependent infrared spectra of the ultrasound initiated SEBS-g-MAH were also analyzed by the perturbation correlation moving window 2D (PCMW2D) correlation spectroscopy. It could confirm that the broken point existed at the joint between poly(ethylene-co-1-butene) (EB block) and polystyrene block (S block). Therefore, the grafting groups were attached to not only the S block but also the EB block. In addition, in order to well understand the aggregation structure of the ultrasound initiated SEBS-g-MAH, the possible grafting mechanism and aggregation model of the ultrasound initiated SEBS-g-MAH at room temperature were also proposed.
Co-reporter:Kangming Xu, Fengshun Zhang, Xianlong Zhang, Qiaoman Hu, Hong Wu and Shaoyun Guo
Journal of Materials Chemistry A 2014 vol. 2(Issue 22) pp:8545-8556
Publication Date(Web):06 Mar 2014
DOI:10.1039/C4TA00476K
In this study, a polyurethane/hindered phenol system was prepared as a melt in order to study the yet unclear mechanism of the formation of hydrogen bonds (H-bonds) in analogous systems. The evolution of intermolecular H-bonds between ester carbonyl/phenolic hydroxyl groups and urethane carbonyl/phenolic hydroxyl groups was detected, for the first time, by infrared analysis. Subsequent dynamic mechanical analysis combined with thermal analysis showed the fluctuation of the glass transition temperatures and the damping properties of the hybrids. From X-ray diffraction analysis the existence was observed of only amorphous hindered phenol in the polyurethane, further molecular dynamic simulation, based on an amorphous cell, characterized the number of H-bonds, the H-bond predominant binding energy and the fractional free volume in a quantitative manner. It was observed that the variation of the simulation data was in accordance with the fluctuation change of the damping properties, thus a relationship was established between the evolution of the H-bonds and the damping properties.
Co-reporter:Fengshun Zhang, Guansong He, Kangming Xu, Hong Wu and Shaoyun Guo
RSC Advances 2014 vol. 4(Issue 40) pp:20620-20625
Publication Date(Web):24 Apr 2014
DOI:10.1039/C4RA00976B
The relaxation behavior and different modes of molecular motion in the miscible blends of asymmetric chlorinated butyl rubber (CIIR) and petroleum resin (PR) were investigated by dynamic mechanical spectroscopy (DMS) and dielectric spectroscopy (DS). The different modes of CIIR molecular motion, attributed to local segmental motion, sub-Rouse modes and Rouse mode relaxation, have been detected from both of the DMS and DS results, and the relaxation times of local segmental motion and Rouse modes could be fitted by the Vogel–Fulcher–Tammann equation. Due to the increased activation energy with increasing PR content, local segmental motion of CIIR is slightly confined, however, Rouse modes of CIIR, which contain more backbone bonds and need a larger free volume than the local segmental motion, are greatly confined. As a result, the relaxation temperature of local segmental motion moves slightly to high temperature but that of Rouse modes moves to high temperature more significantly.
Co-reporter:Chunhai Li, Shuo Yang, Jianfeng Wang, Jiwei Guo, Hong Wu and Shaoyun Guo
RSC Advances 2014 vol. 4(Issue 98) pp:55119-55132
Publication Date(Web):07 Oct 2014
DOI:10.1039/C4RA09302J
In this study, a novel approach is proposed to significantly toughen polypropylene (PP) by fabricating PP and poly(ethylene-co-octene) (POE) into alternating multilayered blends instead of conventional blends. POM, SEM, polarized-FTIR, DSC and XRD were performed to investigate and characterize the microstructure of the alternating multilayered and conventional blends. The crack-initiation term, impact fracture surface and bulk morphologies beneath the fracture surface are inspected in order to understand the differences in the impact behaviors of the alternating multilayered blends and the conventional blends. The results show that the unique multilayered structure has a great advantage in toughening PP. The notable improvement of the toughness of the alternating multilayered blends is ascribed to the synergetic effects of the interfaces' delaminations, craze deflection, larger subcritical damage zone (stress whitening zone) and the combination of the voids and deformation during the fracture process. Moreover, the alternating multilayered blends exhibit high toughness with a low POE content; thus, this work also offers a new method to toughen the materials without an obvious sacrifice of their strength.
Co-reporter:Jianfeng Wang, Cuilin Wang, Xianlong Zhang, Hong Wu and Shaoyun Guo
RSC Advances 2014 vol. 4(Issue 39) pp:20297-20307
Publication Date(Web):24 Mar 2014
DOI:10.1039/C3RA48036D
In this paper, polypropylene (PP) and polypropylene/poly(ethylene-co-octene) blends (PP/POE) were fabricated into alternating multilayered materials to improve the low-temperature toughness of PP efficiently compared with conventional PP/POE blends. POM, SEM, micro-FTIR and part-impact test were performed to characterize and investigate the alternating multilayered microstructure and its relationship with mechanical properties. The results showed that the unique alternating multilayered microstructure could generate a distinctive distribution of POE, resulting in the great change in both macro- and micro-morphology of the materials. Most interestingly, the morphological evolution of the dispersed POE phase before and after the impact showed that a brittle–ductile transition (BDT) layer was formed at the interlayer interface between the adjacent PP layer and the PP/POE layer during the impact process, which was the main reason for the great improvement of the low-temperature toughness. Moreover, the rigidity of alternating multilayered materials was maintained very well because of the existence of the rigid PP layer, indicating that the alternating multilayered microstructure was very helpful to maintain a good balance between toughness and rigidity.
Co-reporter:Jianfeng Wang;Xianlong Zhang;Tianbao Zhao;Liyuan Shen;Shaoyun Guo
Journal of Applied Polymer Science 2014 Volume 131( Issue 7) pp:
Publication Date(Web):
DOI:10.1002/app.40108
ABSTRACT
The sheets of polycarbonate (PC)/polyethylene (PE) in situ microfibrillar composites are successfully prepared directly through multistage stretching extrusion with an assembly of laminating-multiplying elements (LMEs) instead of the secondary processing. The morphological development of the PC dispersed phase in PE matrix with increasing the number of LMEs during multistage stretching extrusion investigated by scanning electron microscope shows that core-skin structure of the microfibrillar PC/PE composites during multistage stretching extrusion with 4 LMEs is weakened, and the diameter of the PC microfibrils is relatively more uniform, indicating that the shear field in LMEs greatly affects the morphology of PC dispersed phase in PE matrix. The tensile, crystalline, melting, orientation and rheological behavior of the PC/PE microfibrillar composites are also investigated. The results show that the PC microfibrils are helpful to increase complex viscosity and yield stress of the PE/PC composites. In addition, it is found that the glass transition temperature of PC in PE matrix reduced with increasing the number of LMEs during dynamic rheological testing. It is coincided with the results of DSC analysis of the PC/PE composites. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40108.
Co-reporter:Fengshun Zhang;Guansong He;Kangming Xu;Shaoyun Guo;Chaoliang Zhang
Journal of Applied Polymer Science 2014 Volume 131( Issue 13) pp:
Publication Date(Web):
DOI:10.1002/app.40464
Abstract
To further investigate the effect of petroleum resin on damping mechanism and different modes of motion of chlorinated butyl rubber (CIIR), two kinds of petroleum resins with different molecular structures, aliphatic C5 resin and aromatic C9 resin, were incorporated into CIIR. The experimental results showed that the aliphatic C5 resin exhibited a better miscibility with CIIR, compared with aromatic C9 resin. With increase in the content of the C5 resin, the α process and the α′ process of CIIR moved to the higher temperature but to different extents, and the effective damping temperature range was broadened remarkably. The CIIR/C9 resin blends showed two loss peaks, which corresponded to the CIIR matrix and the C9 resin dispersed phase, respectively. The C9 resin neither moved different relaxation modes of CIIR to room temperature nor enhanced the value of the loss damping peak. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40464.
Co-reporter:Jianfeng Wang;Jiwei Guo;Chunhai Li;Shuo Yang
Journal of Polymer Research 2014 Volume 21( Issue 12) pp:
Publication Date(Web):2014 December
DOI:10.1007/s10965-014-0618-x
In this paper, SEM, POM, DSC, FTIR, polarized FTIR, and part-impact test were performed to investigate the effect of dispersed POE phase on crystallization kinetics behavior, molecular interaction, and impact-induced morphological evolution in polypropylene/poly(ethylene-co-octene) (PP/POE) blends. The main focus was to establish a systematic and deep toughening mechanism from microscopic molecular interaction to macroscopic deformation. The results showed that the existence of POE particles played the role of an obstacle during the crystallization process of a PP matrix, which could increase the growth path of PP lamellae or ordered PP molecules and reduce the growth space of spherulites, resulting in a slower spherulite growth rate and smaller spherulite size. This behavior was explained by a crystallization model. Most interestingly, a coated structure was formed in the interface, which was a transition state structure of molecules with different morphologies. The as-formed coated structure can be considered the origin of the cavitation effect and impact-induced morphology evolution of POE particles during the impact process. Moreover, micro-plastic deformation in PP/POE blends during the fracture process was a multi-stage mechanism, in which the POE content played a decisive role.
Co-reporter:Liyuan Shen;Xianlong Zhang;Shaoyun Guo
Journal of Applied Polymer Science 2013 Volume 129( Issue 5) pp:2686-2691
Publication Date(Web):
DOI:10.1002/app.38999
Abstract
The functionalization of styrene-b-(ethylene-co-1-butene)-b-styrene tri-block copolymer with maleic anhydride (MAH) in melt state through ultrasound initiation was studied in this article. The effects of plasticizer content and types, MAH content, ultrasound power, and die temperature on grafting ratio of MAH were investigated by means of acid–base titration. Functionalized products were confirmed by new absorption bands in Fourier-transform infrared spectroscopy. The experimental results showed that the ultrasound initiated products had lower complex viscosity (η*), lower gel content as well as lower molecular weight than peroxide initiated products, indicating that the ultrasound could cause chain scission and suppress the crosslinking side reaction to gain functionalized products, which have less gel content and high grafting ratio. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Co-reporter:Xianlong Zhang, Hong Wu, Shaoyun Guo, Yuzhong Wang
Polymer 2013 Volume 54(Issue 20) pp:5429-5436
Publication Date(Web):6 September 2013
DOI:10.1016/j.polymer.2013.07.050
In this paper, effect of phase morphology on water diffusion in phosphorus-containing aromatic liquid crystalline copolyester (P-TLCP) named as poly(-hydroxybenzate-co-DOPO-benzenediol dihydrodiphenyl ether terephthalate) (PHDDT) was investigated by two-dimensional correlation infrared (2DIR) spectroscopy, in order to understand well the relationship between structure and properties of P-TLCP. The phase morphologies of the PHDDT films were observed by polarized light microscope. The experimental results showed that the clear nematic texture, which was observed for PHDDT film treated at 250 °C for 3 min under a nitrogen atmosphere. However, lots of bright spots were observed for untreated PHDDT film due to weak crystallization of PHDDT molecules. Moreover, the density of the untreated PHDDT film (1.1631 ± 0.0257 g/cm−3) was lower than that of the treated one (1.2969 ± 0.0134 g/cm−3), indicating that the arrangement of the molecules in treated PHDDT film was compact in comparison with that in untreated one. Therefore, the average diffusion coefficient of water in treated PHDDT film was lower than that in untreated one. The mechanisms of water diffusion into PHDDT films with different phase morphologies can be obtained through 2DIR analysis in OH stretching and bending bands. It was found that water diffused into the treated PHDDT film by forming moderate hydrogen bonds prior to forming strong and weak hydrogen bonds, while diffused into the untreated one by forming strong and weak hydrogen bonds prior to forming moderate hydrogen bonds. It was also found that the spectral intensity of PO varied prior to that of CO during water diffusion into untreated PHDDT film, which was reversed for treated PHDDT film.
Co-reporter:Bo Peng;Wenting Bao;Shaoyun Guo;Yong Chen;Hua Huang;Shih-Yaw Lai;Jinder Jow
Polymer Engineering & Science 2012 Volume 52( Issue 3) pp:518-524
Publication Date(Web):
DOI:10.1002/pen.22112
Abstract
The reaction of maleic anhydride (MAH) grafted onto propylene-based copolymer (DP) without adding any initiator was conducted through ultrasound assisted extrusion in this article. The effects of ultrasound power, die temperature, and MAH content on the grafting degree and efficiency were studied. With increasing ultrasound power, the grafting degree and efficiency of DP-g-MAH increase. The presence of ultrasound with higher power and lower die temperature is beneficial to increase the grafting degree and efficiency. The increase of MAH content can increase the grafting degree but reduce the grafting efficiency. Based on the results of melt flow index, dynamical rheological, gel permeation chromatograph (GPC), and Fourier transform infrared spectroscopy (FTIR) tests, the mechanisms of the grafting reaction were proposed. POLYM. ENG. SCI., 2012. © 2011 Society of Plastics Engineers
Co-reporter:Bo Peng, Hong Wu, Wenting Bao, Shaoyun Guo, Yong Chen, Hua Huang, Hongyu Chen, Shih-Yaw Lai and Jinder Jow
Polymer Journal 2011 43(1) pp:91-96
Publication Date(Web):November 3, 2010
DOI:10.1038/pj.2010.95
Propylene-based plastomer/nanosilica composites, with a filler content of 1–4 wt%, were prepared by a specially designed ultrasound-assisted extrusion system that was developed in our laboratory. The effects of ultrasound on the morphology, as well as the rheological and mechanical properties of the composites, were studied in this paper. In spite of slight ultrasound-induced degradation of the polymeric matrix, the results showed that the strength and elongation of the composites at break, in most cases, still improve in the presence of ultrasound because of ultrasound-induced homogeneous dispersion of nanoparticles in the polymeric matrix (as confirmed by scanning electron microscope, transmission electron microscope and differential scanning calorimetry studies). Dynamic rheological measurements also indicate that ultrasound-induced compatibilization has a more predominant role than does degradation. From dynamic mechanical measurements, it was found that ultrasound-induced degradation results in a drop in the dynamic storage modulus and glass transition temperature for composites with 4 wt% filler content, whereas ultrasound-induced compatibilization enhances their loss factor values.
Co-reporter:Bowen Yan, Hong Wu, Genjie Jiang, Shaoyun Guo, and Jian Huang
ACS Applied Materials & Interfaces 2010 Volume 2(Issue 11) pp:3023
Publication Date(Web):October 13, 2010
DOI:10.1021/am1003574
This paper describes interfacial crystalline structures found in injection overmolded polypropylene components and the relationship of these structures to bond strength between the components. The combined effects of the development of hierarchical gradient structures and the particular thermomechanical environment near the interface on the interfacial crystalline structures were investigated in detail by PLM, SEM, DSC, WAXD, and infrared dichroism spectroscopy. The experimental results showed that during molding there was competitive formation of interfacial crystalline structures consisted of “shish-kebab” layer (SKL) and a transcrystalline layers (TCL). Variation in shear stress (controlled by injection pressure and injection speed) plays an important role in the formation of the SKL. The formation of TCL is influenced by the thermal environment, namely melt temperature and mold temperature. Increasing within certain limits, interfacial temperature and the thermal gradient near the interface promotes β-iPP growth. The relationship between interfacial crystalline structures and interfacial bond strength was established by lap shear measurement. The interfacial bond strength is improved by enhancing the formation of TCL, but reduced if SKL predominates.Keywords: bond strength; crystalline structure; injection overmolding; interface; polypropylene
Co-reporter:Rong Chen, Chuanbin Yi, Hong Wu, Shaoyun Guo
Carbohydrate Polymers 2010 Volume 81(Issue 2) pp:188-195
Publication Date(Web):11 June 2010
DOI:10.1016/j.carbpol.2010.02.012
The mechanochemical degradation behavior of hydroxyethyl cellulose (HEC) during vibratory ball milling and its induced morphological and structure development of HEC were studied through intrinsic viscosity measurement and scanning electron microscope (SEM), particle size analysis, wide-angle X-ray diffractometry (WAXD) and thermal gravimetry analysis (TG). A degradation kinetic model was proposed to evaluate the effects of ball-milling time on degradation rate of HEC with different initial molecular weights. The fragmentation mechanism is proposed based on the results of FTIR and 13C NMR measurements. The experimental results indicated that the molecular weight decreased sharply with the increase of ball-milling time, charge ratio of steel ball/HEC and the rotational speed. Meanwhile, the fibriform morphology of original HEC was damaged observably and the crystallinity of HEC decreased sharply during the milling, which induced the decrease of the thermal stability.
Co-reporter:Hong Wu;Wenting Bao;Shaoyun Guo
Polymer Engineering & Science 2010 Volume 50( Issue 11) pp:2229-2235
Publication Date(Web):
DOI:10.1002/pen.21759
Abstract
The effect of ultrasound on flow behaviors of metallocene-catalyzed linear low-density polyethylene (mLLDPE) melt in capillary-like die during the extrusion is investigated in this article. The rise in die temperature is found with increasing ultrasound power, especially at lower initial die temperature. At the same die temperature, the presence of ultrasound can decrease the apparent viscosity and the viscous flow activation energy of mLLDPE melt then increase its slip velocity at the capillary wall in the die. The flow behavior of mLLDPE melt is enhanced during ultrasound-assisted extrusion as the presence of ultrasound can enhance the mobility and the orientation of entangled segments. It is also found that ultrasound can break the dispersed phase of mLLDPE/polyolefin elastomer (POE) blend into small pieces thus improve the homogeneous dispersion of POE phase in mLLDPE matrix. A possible mechanism for enhanced flow behaviors of mLLDPE melt because of the presence of ultrasound is also proposed. POLYM. ENG. SCI., 2010. © 2010 Society of Plastics Engineers
Co-reporter:Genjie Jiang;Bowen Yan ;Shaoyun Guo
Polymer Engineering & Science 2010 Volume 50( Issue 4) pp:719-729
Publication Date(Web):
DOI:10.1002/pen.21576
Abstract
The effect of a tie film consisted of polyethylene (PE) and maleic anhydride functionalized PE (PE-g-MAH) on the interfacial adhesion of PE and polymide-6 (PA6) was studied in a sequential injection molding process. It was found that the interfacial adhesion of PE/PA6 was significantly improved via in situ reactive compatibilization. The results showed that the interfacial adhesion increased with PE-g-MAH concentration, and reached a plateau value at the weight fraction of 40%, showed a maximum at a thickness of about 15 μm tie film. Higher the second melt and mold temperature, stronger the interfacial adhesion was obtained. An analysis conducted on the fracture interface by using scanning electron microscopy (SEM) and differential scanning calorimetry (DSC) revealed that the increase of the interfacial adhesion was strongly related to the morphological structure of the fracture interface, which changed from chunks to fibrils, and to a thin layer. The relationship between the interfacial adhesion and interfacial fracture mechanisms was also discussed. POLYM. ENG. SCI., 2010. © 2009 Society of Plastics Engineers
Co-reporter:Genjie Jiang;Tingting Xie;Shaoyun Guo
Journal of Applied Polymer Science 2009 Volume 112( Issue 4) pp:2136-2142
Publication Date(Web):
DOI:10.1002/app.29676
Abstract
To improve the processability of ethylene-α-olefin copolymers (POE), POE and POE/polystyrene (PS) blends were extruded in the presence of ultrasound. On the one hand, the effect of ultrasound on the die pressure drop, extrudate productivity, melt viscosity of POE, and the processing behaviors of POE and POE/PS (80/20) blend were studied. The results showed that with increasing ultrasound power, the die pressure and melt-apparent viscosity of POE decreased whereas the productivity of POE extrudates increased, then the processability of POE was greatly improved. On the other hand, the effects of ultrasound on the morphology, rheological, and mechanical properties of POE/PS (80/20) blend were studied. Capillary rheological results showed that the merger of ultrasound and the addition of PS showed a synergistic improvement of processability of POE. From morphological observation and rheological analysis, the compatibility of the blend was also improved in the presence of 200W ultrasound. As a result, the stress at break of compatibilized POE/PS (80/20) blend increased from 9.2 to 11.0 MPa, and the dynamic storage modulus increased at experimental temperature range, indicating that the mechanical properties of POE/PS blends can be improved by ultrasound-assisted extrusion. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Co-reporter:Genjie Jiang;Bowen Yan;Shaoyun Guo;Jian Huang
Journal of Polymer Science Part B: Polymer Physics 2009 Volume 47( Issue 11) pp:1112-1124
Publication Date(Web):
DOI:10.1002/polb.21719
Abstract
The solid-melt interfaces between polyethylene (PE) and polyamide 6 (PA6) reinforced by in situ reactive compatibilization in a sequential two-staged injection molding process has been studied in this work. The effects of the maleic anhydride grafted PE content and processing parameters, such as injection pressure, injection speed, melt temperature, and mold temperature, on the interfacial adhesion were investigated experimentally. The results of the interfacial adhesion characterized by lap shear measurement showed that the interfacial temperature and heat transfer between PE and PA6 interfaces play a very significant role in the bonding process. The fracture surfaces of the specimens prepared at different calculated interfacial temperature were investigated by scanning electron microscopy (SEM) and differential scanning calorimetry (DSC), which suggested that the fracture failure changes from adhesive to cohesive failure with increasing interfacial temperature. The contribution of crystalline parts of the in situ formed copolymers to the enhancement in interfacial adhesion also was determined by DSC analysis. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 1112–1124, 2009
Co-reporter:Liyuan Shen, Lichao Xia, Teng Han, Hong Wu, Shaoyun Guo
International Journal of Hydrogen Energy (28 December 2016) Volume 41(Issue 48) pp:23164-23172
Publication Date(Web):28 December 2016
DOI:10.1016/j.ijhydene.2016.11.006
Co-reporter:Kangming Xu, Fengshun Zhang, Xianlong Zhang, Qiaoman Hu, Hong Wu and Shaoyun Guo
Journal of Materials Chemistry A 2014 - vol. 2(Issue 22) pp:NaN8556-8556
Publication Date(Web):2014/03/06
DOI:10.1039/C4TA00476K
In this study, a polyurethane/hindered phenol system was prepared as a melt in order to study the yet unclear mechanism of the formation of hydrogen bonds (H-bonds) in analogous systems. The evolution of intermolecular H-bonds between ester carbonyl/phenolic hydroxyl groups and urethane carbonyl/phenolic hydroxyl groups was detected, for the first time, by infrared analysis. Subsequent dynamic mechanical analysis combined with thermal analysis showed the fluctuation of the glass transition temperatures and the damping properties of the hybrids. From X-ray diffraction analysis the existence was observed of only amorphous hindered phenol in the polyurethane, further molecular dynamic simulation, based on an amorphous cell, characterized the number of H-bonds, the H-bond predominant binding energy and the fractional free volume in a quantitative manner. It was observed that the variation of the simulation data was in accordance with the fluctuation change of the damping properties, thus a relationship was established between the evolution of the H-bonds and the damping properties.
![Poly[oxy(1-oxo-1,6-hexanediyl)]](http://img.cochemist.com/ccimg/25300/25248-42-4.png)
![Poly[oxy(1-oxo-1,6-hexanediyl)]](http://img.cochemist.com/ccimg/25300/25248-42-4_b.png)
