【作者】 宋波；

【导师】 王勇；

【作者基本信息】 西南交通大学 ， 材料科学与工程， 2009， 硕士

【摘要】 本论文中对不同分子结构的聚丙烯(PP)如:等规聚丙烯(iPP)、无规聚丙烯PPR3260(3%mol),PPR7726(10%mol),嵌段聚丙烯EPS30R(8%mol)在成核剂诱导下的结晶行为进行了研究。α成核剂为1,3:2,4-二(3,4-二甲基苯甲醛)山梨糖醇(DMDBS),β成核剂为取代芳基酰胺类化合物(TMB-5)。结果表明,PP的成核效果依赖于分子的序列结构。对iPP、PPR3260和EPS30R来说,两种成核剂诱导结晶的效果非常的明显。但对于PPR7726,成核剂没有起到成核的效果。另外,从结晶形貌分析,iPP和PPR3260结晶机理有所不同。接下来对PP-MA及PP/PP-MA(50/50)在成核剂诱导下的结晶和熔融行为进行了研究。结果发现DMDBS虽然对iPP有很好的成核效果,但对含有PP-MA的样品效果不是很明显。然而,无论是iPP,PP-MA还是PP/PP-MA,成核剂TMB-5都有明显的成核作用,β-PP是其主要的晶体结构。对成核剂母料的进一步研究表明,DMDBS在iPP中良好的分散,但在PP-MA中却引起了团聚;TMB-5无论在iPP还是在PP/PP-MA中都有较好的分散。可以得知成核剂的分散性在诱导结晶时起到决定的作用。本论文也对PP-MA和β成核剂诱导PP-MA的等温、非等温结晶动力学进行了研究。在等温和非等温结晶后,对样品升温的熔融行为进行了研究,其结果也反应了样品在等温和非等温下结晶的结晶结构。结果表明,TMB-5对PP-MA是非常有效的成核剂,其加快了PP-MA的结晶速率、增加了成核密度。在结晶过程中生成了大量的β晶体。更多还原

【Abstract】 In this paper,crystallization behaviors of isotactic polypropylene(iPP) with different macromolecular structures,such as isotactic homopolymer polypropylene (iPP),random copolymer PP with 3 mol%polyethylene(PPR3260),random copolymer PP with 10 mol%polyethylene(PPR7726),and 8 mol%polyethylene (EPS30R) were studied through addition of commercialα-form nucleating agent (NA) 1,3:2,4-bis(3,4-dimethylbenzylidene) sorbitol(DMDBS) andβ-form NA aryl amides compound(TMB-5),respectively.The results show that the nucleation efficiency of NA during the PP crystallization process depends on the PP macromolecular structure.DMDBS or TMB-5 has an apparent nucleation effect in iPP and PPR3260,the crystallization temperature is enhanced greatly and the spherulites size is decreased dramatically.However,the crystallization behavior of PPR7726 is not influenced by the addition of DMDBS.Furthermore,compared with the crystallization behavior of iPP with DMDBS,a more interesting phenomenon during the crystallization of PPR3260 with the same DMDBS content is observed.The crystallization and melting behaviors of NAs nucleated iPP, polypropylene grafted by maleic anhydride(PP-MA) and their blend iPP/PP-MA(50/50) were also comparatively studied.DMDBS and TMB-5 were used.It is interesting to observe that,although DMDBS shows excellent nucleation effect for virgin iPP,the crystallization behaviors of PP-MA and blend of iPP/PP-MA are completely independent on the addition of DMDBS.However, whether in iPP,PP-MA or in iPP/PP-MA blend,TMB-5 presents good nucleation effect and theβ-PP is the main crystalline structure.Further results based on the master batch suggest that DMDBS is well dispersed in iPP but aggregated in PP-MA,however TMB-5 shows good dispersion in both iPP and PP-MA.Our results show that the dispersability of NA is one of the key factors determining the nucleation effect of NA.This paper also studys the crystallization behavior of PP-MA with TMB-5. The isothermal and nonisothermal crystallization kinetics of PP-MA and nucleated PP-MA are comparatively researched based on the concentration ofβ-NA of 0.2wt%.Subsequent melting behaviors after isothermal and nonisothermal crystallization processes are also investigated to explore the crystalline structures formed during the crystallization.The results indicate that TMB-5 is still very efficient in influencing the crystallization of PP-MA through increasing the nucleation density and accelerating the spherulites growth rate,leading to large amounts ofβ-phase formation during the crystallization process.更多还原