成核剂对聚丙烯材料结晶形态的影响

利用X射线衍射(XRD)结合图像分析系统对成核聚丙烯(PP)结晶度、晶粒、晶胞结构及球晶形态进行了定量分析研究,结果表明,成核剂的加入对聚丙烯高层次和低层次结晶形态均有影响:在聚集态结构层次,随成核剂加入量增多,球晶尺寸下降,小尺寸球晶增多且分布逐渐变窄,结晶度增大,当成核剂加入量超过0.4%~0.5%(质量分数),球晶尺寸趋于稳定,且结晶度上升幅度变小。成核剂对PP片晶厚度和晶胞结构也有不同程度的影响,晶面法向晶粒尺寸随成核剂加入量增大而下降,(041)晶面最为明显;晶格参量在一定范围内变化,促进晶胞变小,晶胞参量中沿b轴方向的尺寸变化较明显。

Crystalline Morphology of PP Filled with Nucleating Agent

The crystalline morphology of nucleating polypropylene(PP) was analyzed by X-ray diffraction(XRD) and image analysis system after etched.With increasing of the nucleating agent content((Nc)),the crystallinity(Xc) increases and the number-average spherulite size(Dn) decreases and tends towards a uniform distribution,and when the(Nc) value exceeding 0.4%～0.5%,the varietion tending to stabilization.With increasing nucleating agent,the quantity of small spherulites increases and the distribution range tends to narrow.At the same time,nucleating agent also has effect on crystal grain structure and unit cell structure.So,the nucleating agent has effect on different layer of crystalline structure,with increasing(Nc) and compared with pure PP,the unit cell parameters decrease,especially the(041) crystal plane.The volume of the unit cell also decreases with the filling of nicleating agent,especially the size in b-axis,due to along the b-axis the molecular chains are farther away from each other and representing weaker mutual effect,which affected more easily by crystalline conditions when molecular chains array and enter into the crystal lattice.