成核剂二(对甲基苄叉)木糖醇对聚丙烯结晶性能的影响

以对甲基苯甲醛和木糖醇为原料,合成成核剂二(对甲基苄叉)木糖醇(MDBX).以环己烷为反应溶剂,对甲基苯甲醛与木糖醇物质的量比为2.4:1,甲醇和对甲基苯磺酸用量分别为基料质量分数的430%和4.0%时,MDBX的收率最高,为97.7%,熔程为244℃～246℃.以MDBX为成核剂,使用溶液沉淀法制备MDBX质量分数分别为0.0%、0.1%、0.3%、0.5%的粉末聚丙烯样品,采用红外光谱仪、差示扫描量热仪,X衍射仪和偏光显微镜等方法,研究了PP结晶性能.结果表明,MDBX是PP的有效α晶型诱导剂,MDBX的加入能诱导大量球晶生成,结晶度提高,FT-IR,X-ray衍射和DSC等分析结果一致,即在PP中添加0.5%MDBX时,聚丙烯的改性效果最好,PP的结晶度达到最大值.

Effect of 1,3-2,4-di(p-methylbenzylidene) xylitol on crystalline structure and property of PP

1,3-2,4-di(p-methylbenzylidene) xylitol(MDBX) has been synthesized in the lab from p-methyl benzaldehyde and xylitol.Under the optimized reaction conditions that cyclohexane was used as solvent,the molar ratio of p-dimethyl benzaldehyde to xylitol was 2. 4∶1,and the mass fractions of catalyst and accelerator to raw materials were 4.0% and 430% respectively,the yield of MDBX exceeded 97.7%,and the melting point was 244 ℃～246 ℃. A series of PP samples was prepared based on the amount of nucleating agent used. The effect of MDBX on their crystalline structures and thermal property FT-IR,DSC,WAXD,polarized light microscopy,and so on . Extensive experiments demonstrate that MDBX can nucleate PP effectively and efficiently in α form of crystalline morphology,induce the generation of a large spherulites and increase the crystalline density. The great improvement of optical properties can be achieved with 0.5% addition of MDBX.