中文摘要：

通过亲核取代反应,制备了一系列不同接枝率的十八硫醇（C18H37SH）接枝改性聚氯乙烯（PVC）（记作PVCS18）.通过傅立叶变换红外光谱（FTIR）、核磁共振氢谱（1H-NMR）、示差扫描量热仪（DSC）、热重分析（TG）和X射线衍射（XRD）对PVCS18的结构、相变行为、热稳定性和热能行为进行了研究.结果表明,随十八硫醇钠（C18H37SNa）投料的增加,PVCS18接枝率增加,最高达到50.2%.PVCS18相转变的出现,主要是接枝的十八烷基链段贡献的.随接枝率由8.5%增加到50.2%,相转变温度由61.7℃升高到66.3℃,热焓值由5.3 k J/mol提高到50.9 k J/mol,结晶碳原子数从1.4增加到13.8.主侧链间连接键的极性和基团大小明显影响侧链烷基的结晶能力及可结晶碳原子数目.PVCS18的热稳定性较PVC的没有明显热损失行为出现,该材料可在较高的温度下加工使用.

英文摘要：

A series of modified poly（ vinyl chloride）（ PVC） with n-octadecanethiol,denoted as PVCS18,have been prepared through a nucleophilic substitution reaction,where the different substitution degrees（ DS） are realized. The structure,phase change properties and thermal stability of PVCS18 comb-like polymers are systematically characterized by Fourier transform infrared spectroscopy（ FTIR）,hydrogen nuclear magnetic resonance spectroscopy（~1H-NMR）,differential scanning calorimertry（ DSC）,thermogravimetric analysis（ TG） and wide-angle X-ray diffraction（ WAXD）. The results demonstrate that the DS has a big influence on the structure and properties of PVCS18 comb-like polymers. With increasing the DS of C18 alkyl side chains,PVCS18 exhibits an interesting variation for phase transition and thermal performance,contributed from the grafted C18 side chains along PVC backbones. With DS increasing from 8. 5% to 50. 2%,the phase transition temperature changed from 61. 7 ℃ to 66. 3 ℃,the melting enthalpy increased from 5. 3 k J / mol to 50. 9 k J /mol,and the crystallizable number of carbon atoms also increased from 1. 4 to 13. 8,accompanied with the enhanced crystallinity of C18 alkyl side chains. The chemical junction between the main-chain and side-chains has an important effect on the crystallizable number of carbon atom per side chain,and the smaller the polarity and size of chemical junction,the higher the crystallization ability of side alkyl group is. In addition,PVCS18comb-like polymer shows a similar thermals stability with that of pristine PVC,demonstrating that the incorporated alkyl side chains do not alter the thermal stability of PVC,showing a promising application perspective.