成核剂1,3-2,4-二(3,4-二甲基)亚苄基木糖醇的合成及其对聚丙烯的改性

Effect of DMDBX on crystalline structure and properties of PP

以3,4-二甲基苯甲醛和木糖醇为原料合成1,3-2,4-二(3,4-二甲基)亚苄基木糖醇(DMDBX),将DMDBX作为成核剂使用溶液沉淀法制备DMDBX质量分数分别为0、0.1%、0.3%、0.5%、0.7%、0.9%的聚丙烯(PP)样品,采用红外光谱仪、差示扫描量热仪、X射线衍射仪和偏光显微镜等方法,研究了DMDBX对PP结晶结构和结晶性能的影响。结果表明,DMDBX是PP的有效α晶型诱导剂,DMDBX的加入能诱导大量球晶生成,导致结晶峰尖锐,结晶温度区间变窄,结晶度提高15%左右,FT-IR、X射线衍射和DSC等分析结果一致。在PP中添加0.3%～0.5%DMDBX时,聚丙烯的改性效果最好,结晶度达到最大值。采用修正Avrami方程Jeziorny法处理非等温结晶动力学结果表明,添加DMDBX的PP Avrami指数约为3,说明DMDBX起到了异相成核的作用,使PP结晶过程的成核和生长方式发生了改变。

1,3-2,4-di （3,4-dimethyl） benzylidene xylitol （DMDBX） as synthesized in the lab from 3,4- dimethyl benzaldehyde and xylitol, and a series of polypropylene （PP） samples were prepared based on the amount of the nucleating agent, DMDBX used. This work presented the effect of DMDBX on PP crystalline structure and properties. Various techniques including FT-IR, XRD, DSC, polarized light microscopy, etc. were used to investigate the crystalline structures and crystalline properties of the samples. Extensive experiments demonstrated that DMDBX could nucleate PP effectively and efficiently in an a form of crystalline morphology, decrease spherulite size and increase crystalline density, resulting in an increase in the crystallinity temperature, etc. These eventually resulted in an improvement of optical properties.