HDPE/EVOH共混物结晶行为研究

使用示差扫描量热方法对聚乙烯接枝马来酸酐相容改性的HDPE／EVOH共混体系的结品行为进行了研究。实验发现相容作用对HDPE／EVOH共混物中两组分的结晶行为有较大影响,由于熔融共混过程中相容剂与EVOH之间形成的EVOH-g-HDPE对EVOH的结晶具有阻碍作用,导致EVOH分散相的结晶速度下降,晶粒尺寸分布变宽,结晶熔点和结晶度明显低于共混前纯组分。共混物中EVOH分散相对HDPE基体的结晶具有异相成核作用,而且相容作用使异相成核更加明显,从而使HDPE相结晶速度加快,结晶度增大。

Crystallization Behavior of HDPE/Poly (ethylene-co-vinyl alcohol) Blends

Crystallization behavior of HDPE/EVOH blends compatibilized with maleic anhydride-grafted HDPE was investigated using differential scanning calorimetry. It was found that the crystallization behaviors of the two components in the blends were significantly influenced by the compatibilizing effect. The constraint effect of EVOH -g-HDPE, formed by the reaction of maleic anhydride with the hydroxyl groups of EVOH during the melt blending, on the crystallization of the EVOH component gave rise to a slow crystallization rate and broad distribution of crystallite size. The melting temperature and the crystal-linity of the EVOH phase were also substantially decreased, compared with the pure EVOH resin before mixing. The crystallization of HDPE in the blends was facilitated by heterogeneous nucleation induced with the presence of EVOH crystallites, and the nucleation effect became more evident in the compatibilized blending systems, resulting in a faster crystallization rate and a higher crystallinity of HDPE component.