摘要
应用差示扫描量热方法研究了不同表面改性碳酸钙纳米粒子对聚丙烯 (PP)等温与非等温结晶动力学的影响 ,并研究了上述各聚丙烯结晶样品的熔融行为和晶型 .研究发现纳米碳酸钙具有明显的成核效应 ,并具有较强的诱导 β 型结晶的能力 ,而且与粒子的表面处理密切相关 .
Mechanical properties of polymers can be improved by. incorporating nanoparticles, however, there are few works about the influence of nanoparticles on the crystallization mechanism of polymers. To develop an understanding of the important role of nanoparticles in polymer crystallization, the current paper introduced different surface modifications, for calcium carbonate nanoparticles, and studied their effects on the crystallization behavior of isotactic polypropylene (iPP) by DSC measurement. The CaCO3 particles used are 40 nm in diameter, and their surfaces were treated by stearic-coating , PS-grafting, and PBA-grafting methods, respectively. The isothermal crystallization, results show that the addition of both neat and modified nano-CaCO3 into PP has an obvious nucleating effect on the crystallization of iPP, resulting in lower supercooling degree, higher rate of nucleation and overall rate of crystallization, and higher crystallinity. Even through. grafted PBA and PS belong to amorphous polymers, their evident nucleating effects indicate some. regular structure forming on the particles surface.. However, the grafted PBA exhibits different effect from PS because of its distinct molecular polarity and stiffness. On the other hand, the non-isothermal crystallization results show that the addition. of these nano-CaCO3 reduced the rate of nucleation and overall rate of crystallization of iPP, which is related with the slower formation procedure of beta-form crystallites of iPP. The melting behavior and WAXD results revealed that all of these nano-CaCO3 have a strong promoting effect on the nucleation and crystallization of beta-form crystallites of iPP, especially for the systems. containing modified, fillers,implying that this promoting effect was strongly dependent on the surface modifications of the nano-CaCO3 particles.
出处
《高分子学报》
SCIE
CAS
CSCD
北大核心
2003年第3期381-386,共6页
Acta Polymerica Sinica
基金
广东省科技计划项目"十五"规划重大专项 (项目号A10 70 2 )
广东省自然科学基金 (基金号 990 2 77)
广东省自然科学基金团队项目资助
