有机磷酸盐成核剂粒径对PP性能的影响

通过调控反溶剂法中的转速、反溶剂与溶剂配比、溶液浓度等条件制备了不同粒径的2,2’–亚甲基双(4,6–二叔丁基苯基)磷酸钠(NA–40)成核剂,考察了NA–40粒径对等规聚丙烯(i PP)力学性能的影响,并利用差示扫描量热(DSC)仪研究了NA–40粒径对i PP结晶性能的影响。结果表明,随着NA–40粒径的增加,NA–40对i PP力学性能的改善作用变弱。NA–40平均粒径为(17.7±2.2)μm时,i PP/NA–40–1的弯曲弹性模量、弯曲强度和拉伸强度与纯i PP相比,分别提高了44.5%,20.5%和8.3%,相应的缺口冲击强度有所降低;当NA–40平均粒径为(52.6±1.1)μm时,i PP/NA–40–4的弯曲弹性模量、弯曲强度和拉伸强度的增幅分别降至16.8%,2.3%和6.4%。在较低的降温速率下,NA–40粒径对结晶峰值温度(Tc)的影响不明显,提高降温速率对Tc的影响开始显现。用扫描电子显微镜观察NA–40形貌发现,NA–40呈棒状,加工过程影响NA–40粒径,但对NA–40形貌没有影响。利用偏光显微镜观察NA–40在i PP熔体中的分散性,粒径较小的NA–40能够均匀分散在i PP熔体中,而粒径较大的分散性差,大大降低了NA–40的有效成核浓度,影响了NA–40对i PP力学性能及结晶性能的改善作用。

Effects of Particle Sizes of Organic Phosphate Nucleating Agent on PP Properties

Sodium 2,2’-methylene-bis-(4,6-di-t-butylphenylene) phosphate (NA–40) nucleating agents with different particle sizes were produced by controlling rotation rate,sovent/anti-solvent ratio and solution concentration through antisovent method. The effects of particle size on isotactic polypropylene (iPP) crytalization properties and mechanical properties were studied. The re-sults shows that mechnical properties are impoved with the decrease of nucleating agents particle sizes. When the nucleating agent average particle size is (17.7±2.2)μm,the flexural modulus,flexural strength and tensile strength of iPP are impoved by 44.5%, 20.5% and 8.3% respectively,compared with pure iPP. When the nucleating agent average particle size is (52.6±1.1)μm,the flexural modulus,flexural strength andtensile strength of iPP are impoved by 16.8%,2.3%和6.4% respectively. The influence of nucleating agents particle is not obvious unless the cooling rate reach a certain level. Observing NA–40 with SEM,which shows a bars-like morphology. The anti-solvent processing did not changed the morphology of NA–40 except for particle size. using POM to study the dispersity of NA–40 in iPP,and the results shows that NA–40 with smaller particle size disperse well in iPP,while those with larger size cannot disperse very well,which may greatly reduce the effective concentration of NA–40 and affect NA–40 on the improvement of the mechanical properties and crystallization behaviors of iPP.