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Yao C.,CAS Institute of Chemistry | Yao C.,University of Chinese Academy of Sciences | Yang G.,CAS Institute of Chemistry | Yang G.,Shanghai Genius Advanced Material Co.
Polymer | Year: 2010

A new type of poly(ether-ester) based on poly(trimethylene terephthalate) as rigid segments and poly(ethylene oxide terephthalate) as soft segments was synthesized and its crystallization behavior and morphology were investigated. Differential Scanning Calorimetry revealed that the copolymer containing 57 wt% soft segments presented a low glass transition temperature (-46.4 °C) and a high melting temperature (201.8 °C), suggesting that it had the typical characteristic of thermoplastic elastomer. With increasing soft segment content from 35 to 57 wt%, the crystallization morphology transformed from banded spherulites to compact seaweed morphology at a certain film thickness, which was due to the change of surface tension and diffusivity caused by increasing the soft segment content. Moreover, with the decrease of film thickness from 15 to 2 μm, the crystallization morphology of the copolymer (57 wt% soft segment) changed from wheatear-like, compact seaweed to dendritic. Scanning Electron Microscopy revealed that some flower-like crystals presenting in the bulk, which had been surprisingly found in the poly(ether-ester) segmented block copolymers for the first time. Possible mechanism was discussed in the text. © 2010 Elsevier Ltd. All rights reserved.


Chen Z.,Zhejiang University | Yao C.,Shanghai Genius Advanced Material Co. | Yang G.,Zhejiang University | Yang G.,Shanghai Genius Advanced Material Co.
Polymer Testing | Year: 2012

Poly(trimethylene terephthalate)/polyethylene glycol (PTT/PEG) copolymers, with PEG content ranging from 27.2 to 47.4 wt%, were synthesized by melt copolycondensation. Wide-Angle X-ray diffractometer revealed that all copolymers had the same crystal structure of homo-PTT at room temperature. All copolymers could form ring-banded spherulites, and band spacing increased with increasing PEG content at a given crystallization temperature. Nonisothermal crystallization morphology of copolymers was greatly influenced by cooling rate. When the cooling rate was 2.5 °C/min or lower, banded patterns were absent, whereas when the cooling rate was 20 °C/min or higher, a novel crystal morphology composed of non-banded spherulites (central part) and ring-banded spherulites with decreasing band spacing along the radial growth direction was observed. Moreover, the size of the non-banded spherulitic part decreased with increasing cooling rate. Finally, the nonisothermal crystallization kinetics of copolymers were analyzed and only the Mo method was satisfactory to accurately describe this system. © 2011 Elsevier Ltd. All rights reserved.


Chen Z.,Zhejiang University | Liu Y.,Shanghai Genius Advanced Material Co. | Yao C.,Shanghai Genius Advanced Material Co. | Yang G.,Zhejiang University | Yang G.,Shanghai Genius Advanced Material Co.
Polymer Testing | Year: 2012

A series of poly(trimethylene terephthalate)/poly(ethylene oxide terephthalate) copolymers with approximately 25 wt% PEG content were synthesized and investigated. The results showed that the thermal stability of copolymers increased with increasing M n, PEG from 1000 to 4000 g/mol. However, the thermal stability of the copolymer with M n, PEG = 300 g/mol was better than the copolymer with M n, PEG = 600 g/mol. The nonisothermal crystallization kinetics of the copolymers was analyzed using Ozawa and Mo models, and only the Mo method was satisfactory in describing this system. Polarized optical microscopy revealed that all copolymers could form ring banded spherulites and the temperature window for their formation was basically identical for all copolymers. In addition, the spherulitic growth rate curves of copolymers exhibited a bell shape, and both the maximum growth rate and the crystallization temperature corresponding to the maximum growth rate increased with the increase in M n, PEG. © 2012 Elsevier Ltd. All rights reserved.


Fu X.,Hefei University of Technology | Fu X.,Shanghai Genius Advanced Material Co. | Yao C.,Shanghai Genius Advanced Material Co. | Yang G.,Hefei University of Technology | And 2 more authors.
RSC Advances | Year: 2015

This paper reviews recent advances in polyamide 6 (PA6) nanocomposites with graphene-based fillers including current works using graphite nanoplatelet fillers. Almost all of the latest important publications relating to the preparation, morphology and properties (such as thermal stability, thermal conductivity, electrical conductivity, mechanical properties, and flame retardant and gas barrier properties) of graphene/PA6 nanocomposites are summarized. An outlook of the current challenges in this field is provided for a potential guide to progress in the development of graphene/polymer nanocomposites too. © The Royal Society of Chemistry 2015.


Chen Z.,Zhejiang University | Liu Y.,Shanghai Genius Advanced Material Co. | Yao C.,Shanghai Genius Advanced Material Co. | Yang G.,Zhejiang University | Yang G.,Shanghai Genius Advanced Material Co.
Polymer Engineering and Science | Year: 2013

Poly(trimethylene terephthalate)-poly(ethylene oxide terephthalate) block copolymer (PTG)/multiwalled carbon nanotubes (MWCNTs) composites were prepared via in situ polymerization. To improve the dispersion of MWCNTs in the PTG matrix, the poly(ethylene glycol)-grafted multiwalled carbon nanotubes (MWCNT-PEG) were produced by the "graft to" method. The transmission electron microscopy observation demonstrated that a homogeneous dispersion of MWCNT-PEG was obtained. As a consequence, the percolation threshold for the rheology was around 0.5 wt% and the conductivity was ∼1 wt%, respectively. Differential scanning calorimetry and polarized optical microscopy results confirmed that MWCNT-PEG can act as an effective heterogeneous nucleating agent. Interestingly, the effects of MWCNT-PEG on crystallization and melting of the poly(ethylene oxide terephthalate) blocks were more pronounced than on those of the PTT blocks. Copyright © 2012 Society of Plastics Engineers.


Fu X.,Hefei University of Technology | Liu Y.,Shanghai Genius Advanced Material Co. | Zhao X.,Zhejiang University | Zhao D.,Hefei University of Technology | And 3 more authors.
Journal of Applied Polymer Science | Year: 2015

In this study, we report our progress toward an effective method to prepare polyamide 6 (PA6)/multilayer graphene (MLG) nanocomposites via in situ polymerization. The thermal and mechanical properties of PA6 nanocomposites were investigated with low unmodified MLG content of 0.01-0.5 wt %. The dispersion of MLG sheets in the host matrix was studied in extensive detail while the properties of the resultant nanocomposites were systematically measured. Results indicate that the mechanical properties of the nanocomposites were significantly enhanced; the flexural modulus, flexural strength and impact strength increased by ~97%, ~69%, and ~76% relative to pristine PA6. Furthermore, the thermal stability of nanocomposites was enhanced and the weight loss temperature of PA6 was increased ~15°C at 0.5 wt % content of MLG. Moreover, incorporation of low loading of MLG can increase the crystallization speed of PA6 composites and promote the formation of the γ-crystalline phase while also improving the crystallization temperature. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42742.


Yao C.,CAS Institute of Chemistry | Yao C.,University of Chinese Academy of Sciences | Yang G.,CAS Institute of Chemistry | Yang G.,Shanghai Genius Advanced Material Co.
Polymer International | Year: 2010

The sol-gel technique has provided promising opportunities for the preparation of polymer/inorganic hybridmaterials at the molecular level, which ensures the inorganic particles are well dispersed in the organic matrix. In this work, poly(trimethylene terephthalate) (PTT)/silica nanocomposites were fabricated via the sol-gel technique and in situ polymerization. Fourier transform infrared and nuclear magnetic resonance analyses confirmed that some PTT molecular chains were grafted to the surfaceof silica. UnlikepurePTT, thegraftedPTTwas insoluble inamixedsolvent of chloroformandhexafluoro-2-propanol.Both transmission electron microscopy and scanning electron microscopy showed that the silica particles, with a size of 40-50 nm, were homogeneously dispersed in the PTT matrix with no preferential accumulation in any region. Differential scanning calorimetry revealed that the glass transition temperature and cold-crystallization peak of the composites gradually increased with increasing silica loading. A simultaneous increase of stiffness and toughness was observed for the nanocomposites. Moreover, polarized opticalmicroscopy showed that the nanocomposites exhibited interesting banded spherulites, whichwere different from banded spherulites of PTT previously reported. The nanocomposites with covalent bonding between silica and PTT gave a series of interesting results, such as elevated glass transition temperature, simultaneous increase of stiffness and toughness as well as surprising banded spherulites. © 2009 Society of Chemical Industry.


Chen Z.,Zhejiang University | Liu Y.,Shanghai Genius Advanced Material Co. | Yao C.,Shanghai Genius Advanced Material Co. | Yang G.,Zhejiang University | Yang G.,Shanghai Genius Advanced Material Co.
Polymer International | Year: 2013

Double crystalline poly(trimethylene terephthalate)/poly(ethylene oxide terephthalate) copolymers (PTT/PEOT), with PTT content ranging from 16.5 to 65.5 wt%, were synthesized by melt copolycondensation. The morphological transformation of samples from microphase separation to macrophase separation was investigated by gel permeation chromatography and transmission electron microscopy. Differential scanning calorimetry and in situ wide-angle X-ray diffraction suggested that all copolycondensation samples displayed double crystalline behavior. The melt-crystallization peak temperatures (Tm, c values) of PTT chains monotonously increased with increasing PTT content and were higher than that of homo-PTT when the content of PTT was above 30.6 wt%. Interestingly, Tm, c values of PEOT chains were also increased with increasing PTT content. Polarized optical microscopy revealed that all copolycondensation samples studied could form ring-banded spherulites and band spacing increased with increasing Tc values. In addition, band spacing decreased with increasing PTT content at a given Tc. Strangely, although PEOT was the main component in all copolycondensation samples, spherulitic morphology formed by the advance crystallization of PTT did not change after PEOT crystallization. Only a subtle change of quadrant tones was detected. © 2012 Society of Chemical Industry.


Yao C.,CAS Institute of Chemistry | Yao C.,University of Chinese Academy of Sciences | Yang G.,University of Chinese Academy of Sciences | Yang G.,Shanghai Genius Advanced Material Co.
Journal of Polymer Science, Part B: Polymer Physics | Year: 2010

A new type poly(ether-ester) based on poly(tri- methylene terephthalate) as rigid segments and poly(ethylene oxide terephthalate) as soft segments was synthesized and its aging behavior were investigated. Different from other polymer, the segmented block copolymers exhibited a unique aging mechanism. That is, the degradation of mechanical property within short term annealing was due to the overgrown crystals and dramatically increased crystallinity, which was proved by field emission scanning electron microscope (FE- SEM) and differential scanning calorimetry (DSC), respectively. The deterioration in mechanical property after long term annealing was the results of both the increase in crystallinity and the decrease in molecular weight. Moreover, FE-SEM showed many interesting flower-like crystals presented on the surface of annealed sample. The flower-like crystals consist of several radialized petal-like arms and a more densely packed center, which has been seldom found in polymer bulk. Wideangle x-ray diffraction results showed that the copolymer has the same crystal structure as PTT. Such poly(ether-ester) or its blends with other polymer could be suitable for rapid degradable products, such as package and vessel. © 2010 Wiley Periodicals, Inc.

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