挤出机头内流场对玻纤取向和分布的影响

Influence of flow field in extrusion dies on orientation and distribution of glass fiber

引言玻璃纤维可明显增强高分子材料,但加入的量一般较高（如30%）,而有机改性蒙脱土（MMT）可在低含量（如3%～5%）下较显著地提高高分子材料的物理性能[1]。

In the current work,flow fields in both straight and divergent dies were analyzed,and the circumferential stretch rate in the divergent channel was derived.The glass fiber orientation and distribution across the thickness of samples extruded from both dies at two flow rates were studied.The formation mechanism of aforementioned glass fiber orientation and distribution was explained by using the distribution of shear and stretch strain rates.The results showed that most of the glass fibers were aligned in the flow direction in the samples extruded from the straight die.A five-layered structure,including two skin layers,two sub-skin layers,and a core layer,formed across the thickness of the samples extruded from the divergent die.It was first found that the fibers exhibited a ＂W＂ type alignment in the core layer.It was also demonstrated that the glass fiber alignments were affected more remarkably by the strain rate than the strain.