基于薄膜近似和neo-Hookean本构关系，建立了描述塑料挤出吹塑中型坯自由吹胀的数学模型。在实验方面，采用视频图像捕获技术获得了吹塑模具型腔内型坯吹胀的瞬态图像。比较发现，理论预示的型坯轮廓分布与实验观察结果较吻合。型坯中部的胀大速率要比两端的大得多，且在很低的吹胀压力（本研究约为20kPa）下即与模具型腔接触。本文还预示了型坯中截面半径对吹胀压力、材料模量和型坯起始壁厚的依赖性。型坯的胀大速率随材料模量或型坯起始壁厚的减小而提高。本文建立的数学模型还可用于预示型坯自由吹胀过程中局部的拉伸比、轴向与周向的局部应力分布以及壁厚分布。

The dependence of the diameter swell and sag of a parison extruded from blends of high-density polyethylene (HDPE)/polyamide-6 (PA6)/compatibilizer on the blend composition and flow rate is determined by analyzing video images of the parison. Among the blends tested, blends with a PA6 concentration of 35% or below exhibit an appreciable swell. A greater degree of sag begins to appear for the blend with a PA6 content of 45%. A neural network approach is applied to the experimental data, leading to a model for predicting the diameter swell profile from new levels of input variables, including the blend composition and flow rate.

A neural network-based model approach is presented in which the effects of the die temperature and flow rate on the diameter and thickness swells of the parison in the continuous extrusion blow molding of high-density polyethylene (HDPE) are investigated. Comparison of the neural network model predictions with experimental data yields very good agreement and demonstrates that the neural network model can predict the parison swells at different processing parameters with a high degree of precision (within 0.001).  2002 Elsevier Science Ltd. All rights reserved.

Continuous extrusion was studied of self-reinforced high density polyethylene (HDPE) sheets from flow-induced crystallization at die pressures varying from 30 to 60 MPa. Their morphology, thermal behavior, tensile strength, and light transmit-tance were tested. Flow fields of a polymer melt through a converging wedge channel were also investigated by direct visual observations in conjunction with a theoretical analysis. The extensional strain rate increased abruptly as the melt approached the exit of the converging channel, this resulting in a higher crystallization rate. So, achieving the crystallization of molecular chains just in front of the exit of the converging channel may favor to extrude the bulk polymeric materials having high properties under lower pressures (e.g., 40 MPa or lower), this having been realized in the present work. The tensile strength of the self-reinforced HDPE sheet prepared at a 40 MPa pressure was enhanced by a factor of 8.