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Zhang S.,Center for Degradable and Flame Retardant Polymeric Materials MoE | Zhang S.,South China University of Technology | Wang X.,Center for Degradable and Flame Retardant Polymeric Materials MoE | Wang Y.,Center for Degradable and Flame Retardant Polymeric Materials MoE
Advanced Materials Research | Year: 2011

Dialdehyde starch has been used to improve comprehensive properties of thermoplastic starch (TPS) in this study. Dialdehyde sweet potato starch (DASS) with various carbonyl contents has been prepared using sodium periodate to oxidize sweet potato starch in the neutral condition. The structure properties of DASS were analyzed by SEM and XRD. The results demonstrate that DASS with the higher carbonyl content comprise lower crystallization. The thermal, mechanical and biodegradable properties of TPDASS were investigated, and the results illustrate that the moisture adsorption and biodegradable ratio decreases with the Tg of TPDASS with higher carbonyl content. This phenomenon could be attributed to the partial cross-linking of DASS which is due to semi-acetal formation by itself. Meanwhile, the mechanical properties of TPDASS95 were less sensitive to the content of plasticizer. The tensile strength could reach even 12.9 MPa while the water content was higher than 13.5% and the biodegradable ratio was 28%. © (2011) Trans Tech Publications, Switzerland. Source


Zhang J.,Center for Degradable and Flame Retardant Polymeric Materials MoE | Zhou Q.,Center for Degradable and Flame Retardant Polymeric Materials MoE | Jiang X.-H.,Center for Degradable and Flame Retardant Polymeric Materials MoE | Du A.-K.,Center for Degradable and Flame Retardant Polymeric Materials MoE | And 3 more authors.
Polymer Degradation and Stability | Year: 2010

A catalytic system based on Na2WO4/CH3COOH/H2O2 effectively oxidizes natural rubber (NR) to prepare telechelic epoxidised liquid natural rubber (TELNR). The Na2WO4/CH3COOH/H2O2 catalytic system possesses a much higher epoxidation efficiency than the traditional CH3COOH/H2O2 system: the epoxidation degree (Xepoxy) of products increases from merely 5.6% (CH3COOH/H2O2) to values as high as 52.1% (Na2WO4/CH3COOH/H2O2) by reacting for 24 h at 60 °C. Moreover, this catalytic system also induces hydrolytic degradation so that the weight average molecular weight (over(Mw, -)) of NR decreases, e.g., from 14.10 × 105 Da (NR) to 0.57 × 105 Da (TELNR) after reacting for 30 h. The catalytic process probably proceeds via a mononuclear tungsten peroxo-species with coordinated peracetyl/acetyl group, as suggested by ESI-MS measurements. During oxidation, the tungstic anion [W(CH3COOO)(O)(O2)2]- not only catalyzes NR epoxidation, but also induces a further oxidation of epoxy groups to form ketones and aldehydes. © 2010 Elsevier Ltd. All rights reserved. Source


Zhu J.,Center for Degradable and Flame Retardant Polymeric Materials MoE | Dong X.-T.,Center for Degradable and Flame Retardant Polymeric Materials MoE | Wang X.-L.,Center for Degradable and Flame Retardant Polymeric Materials MoE | Wang Y.-Z.,Center for Degradable and Flame Retardant Polymeric Materials MoE
Carbohydrate Polymers | Year: 2010

A novel biodegradable ethyl cellulose (EC) grafting copolymer with poly(p-dioxanone) side-chains were successfully synthesized via ring-opening polymerization (ROP) of p-dioxanone (PDO) with a tin 2-ethylhexanoate (Sn(Oct)2) catalyst in bulk at 120 °C. By adjusting the molar ratios of PDO monomer to EC, the different side-chain lengths can be introduced onto EC backbone. The thermal properties and crystalline behaviors of EC-g-PPDO copolymers (EGPs) were different from those of linear PPDO. Furthermore, the in vitro degradation rate of EGPs was faster than the linear PPDO counterpart, and the degradability of grafting copolymers was decreased with the increase of the crystallinity of PPDO side-chains. © 2009 Elsevier Ltd. All rights reserved. Source


Zhang S.-D.,Center for Degradable and Flame Retardant Polymeric Materials MoE | Zhang Y.-R.,Center for Degradable and Flame Retardant Polymeric Materials MoE | Wang Y.-Z.,Center for Degradable and Flame Retardant Polymeric Materials MoE | Wang X.-L.,Center for Degradable and Flame Retardant Polymeric Materials MoE
Advanced Materials Research | Year: 2013

In this study, Dialdehyde sweet potato starch (DASS) with various carbonyl contents had been prepared by sodium periodate in the neutral condition and applied to improve the comprehensive properties of thermoplastic starch. Thermoplastic dialdehyde sweet potato starches (TPDASS) was prepared by thermal press when glycerol was added as a plasticizer. The thermal properties, moisture adsorption, mechanical and biodegradable properties of TPDASS were investigated. The results illustrated that at higher carbonyl content, the moisture adsorption and biodegradable ratio decreased with the increasing Tg of TPDASS, which may attribute to the partial cross-linking of DASS. The highlight properties of TPDASS95 were that: its tensile strength could reach 12.9 MPa even water content was 13.5%. © (2013) Trans Tech Publications, Switzerland. Source

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