二(3,4-二甲基二苄叉)山梨醇对聚乙烯结晶结构及性质的影响

Effect of 1,3-2,4-Di-(3,4-Dimethyl-Benzylidene) Sorbitol on Crystalline Structures and Crystallization Behaviors of Polyethylene

以山梨醇与3,4-二甲基苯甲醛为合成原料,通过缩醛反应合成出苄基类山梨醇成核剂二(3,4-二甲基二苄叉)山梨醇(DMDBS)。使用溶液沉淀法制备了DMDBS质量分数分别为0%和0.3%的粉末聚乙烯(PE)样品,采用X射线衍射仪、红外光谱仪、偏光显微镜、差示扫描量热仪等研究了结晶结构和结晶性质,并用Avrami模型和Kissinger方程计算了PE样品动力学参数。结果表明,DMDBS保持了PE晶体的稳定性,提高了成核密度,结晶度由60.08%提高至64.91%,球晶尺寸由65μm降至51μm;DMDBS能够提高PE结晶速率,促进异相成核过程,结晶活化能从484kJ/mol降至351kJ/mol,Avrami指数由4.0减小至3.2。

1,3-2,4-di-（3,4-dimethyl-benzylidene） sorbitol （DMDBS） was synthesized from sorbitol and p-ethyl- benzaldehyde by acetalization reaction. Mass .fraction of 0 % and 0.3 % DMDBS was respectively introduced into polyethylene by a solution-precipitation method, forming several samples in order to investigate their properties. Crystalline structures and behaviors of PE materials were measured by X-ray diffractometer, infrared spectrometer, polarized light microscopy, differential scanning calorimeter. It showes that DMDBS can maintain the crystal stability and improve the nucleation density for the PE samples. This compound can increase PE crystallinity from 60.08 % to 64.91% and decrease the spherulite size from 65μm to 51 μm. The kinetic analysis reveals that DMDBS can increase the crystallization rate and significantly promote the heterogeneous nucleation process, the activation energy is reduced from 484 kJ/mot to 351 kJ/mol, Avrami exponent is declined from 4.0 to 3.2.