凝胶丁腈共聚弹性体增韧聚甲醛的加工流变行为及力学性能

研究了聚甲醛(POM)/凝胶丁腈共聚弹性体(GNBE)共混物的熔体流动指数(MFI)、高压毛细管流变行为和力学性能。结果表明,共混物MFI随GNBE用量的增加下降较大。聚酰胺(PA)对POM/GNBE共混体系的MFI影响较小,而热塑性酚醛树脂(PFR)的影响显著。当PFR的质量份为4时,POM共混物的MFI达最小值(0.053g/min),约为未加增容剂POM共混物MFI的1/6。随着剪切速率的提高,共混物剪切黏度迅速与POM接近。这种黏度变化行为说明共混物比GNBE对剪切速率更敏感,共混物的黏度受POM的影响较大。随着剪切速率的提高,POM与GNBE的黏度比迅速减小,并接近1,说明POM和GNBE在高剪切速率下共混时,GNBE的液滴能够在POM连续相中分散达到最小。含20份GNBE的POM共混物在高剪切速率下的熔体表观黏度与POM相当;在PFR质量份为6时,POM共混物的缺口冲击强度达到21.6kJ/m2,超过了GNBE质量份为40的POM共混物。当PFR质量份为4时,共混物的缺口冲击强度为对应的不加增容剂共混物的冲击强度的2倍多,扯断伸长率提高了55.4%。

Rheological behavior and mechanical properties of polyoxymethylene/gel acrylonitrile -butadiene elastomer blends

The rheological behavior and mechanical properties of polyoxymethylene (POM)/gel acrylonitrile-butadiene elastomer (GNBE) blends were investigated. The results showed that melt flow index(MFI) of the blends descended as increasing of GNBE content. The effect of compatibilizers of PA and PFR on MFI of POM/GNBE blends was evaluated. PFR was more effective than PA to decrease MFI of the blends. When PFR was 4 phr, the MFI of POM/GNBE blends reached minium value of 0.053 g/min, about 1/6 of the blend without PFR compatibilizer. At high shear rate, apparent viscosity of the blends became small and reached to that of POM. The rheological behavior showed that the apparent viscosity of the blends was more influenced by POM. When the share rate increased, the viscosity ratio decreased quickly and reached to 1. GNBE exhibited better effect on the impact modification of POM. When 20 phr GNBE was added to POM with 6 phr PFR, the charpy impact strength and elongation at break of the blends increased to 21.6 kJ/m2 and 133%, respectively.