双向拉伸对尼龙6-66薄膜的性能影响研究

Effect of Biaxial Orientation on the Properties of PA6-66 Films

通过挤出流延的方法制备了尼龙6-66薄膜,采用双向拉伸试验机对薄膜进行双向拉伸。研究发现,拉伸促进了尼龙6-66的结晶行为,尼龙6-66的结晶度随拉伸比的增加而提高。拉伸后薄膜中仅存在α晶型,随拉伸比的增加,薄膜(002)晶面的衍射强度逐渐增加,表明拉伸比的提高有助于α晶的c轴沿薄膜法线方向取向。拉伸后,薄膜在纵向(MD)和横向(TD)方向的拉伸强度均随拉伸比的增加而增大,双向拉伸薄膜的力学性能在MD和TD方向几乎相等。拉伸后,薄膜的阻隔性能显著提高,当拉伸比为3×3时,薄膜的水蒸气和氧气阻隔性能分别提高约1.2和0.7倍。研究还发现,双向拉伸薄膜的收缩率随拉伸比提高而增大,MD和TD方向的收缩率基本一致。

The polyamide 6-66 films were prepared via extrusion film casting, and then the casted rams were biaxially oriented. It was found that the orientation facilitated the crystallization behavior of PA6-66, whose crystallinity increased as increasing stretch ratio. The stretched films only had α-form crystals. The increased stretch ratio would induce the gradually increased diffraction intensity of （002） plane, suggesting that the c-axis of α-crystal saligns along the normal direction of films. As increasing stretch ratio, the tensile strengths of the film in MD and TD both increased, which are almost equal in the two directions for the equi- biaxially oriented films. The barrier properties increased as the films were stretched. Specifically, as the stretch ratio reached up to 3×3, the water vapor and oxygen barrier properties increased 1.2 and 0. 7 folds, respectively. Furthermore, it was found that as increasing the stretch ratio, the thermal shrinkage of the stretched films increased as increasing the stretch ratios. In contrast, the equi-biaxially stretched films exhibited almost equal shrinkage in MD and TD.