Studies On The Thermal Deformation Behavior Of Injection Molding Products In Temperature Field And The Influence Of Heat Treatment On Mechanical Properties

The dimension stability of injection molding products is very important, and theinfluence of the environment temperature on dimension stability cannot be ignored.When the product is using in a high temperature field, because of the processes ofinjection molding, polymer chains have different degrees of orientation in injectionmolding parts, the thermal motion of the oriented molecular will be enhanced, leadingto macroscopic size shrinkage. When the injection product is using in a gradienttemperature field, temperatures of the product are not uniformity, so that the internalstresses and orientation will be relaxed asymmetry and the product has a distortion. Toreduce the thermal deformation, usually, we pre-treat the post-molding products in theuniform temperature field for long time, and fully contracted before put into using,however, the pre-treat process effects the mechanical properties significantly.In this paper, the content includes three parts:1. Through the DSC and variable temperature infrared spectrum we analyzed thecharacteristics of stress relaxation and conformation rotation of poly-molecular intemperature field. Through the experiments of PC and PC/PBT blend injection partsheated in a uniform temperature field, we simulated the results of the experiments,and built up a high-elastic deformation model, the simulation results agree withexperimental results, so the theory model is basically reliable.2. Through one-side heating experiments of PC/PBT blends injection moldingparts, we simulated the temperature filed and built up a mechanical model to calculatethe injection parts distortion properties, and the calculated results are in goodagreement with the experimental results.3. We studied different parameters of heat treatment on PC and PC/PBT injectionmolding products, which influence the products mechanical properties. Through theanalyses of DSC curve, it indicates that the mechanical properties of PC productsdepend on the cohesion entanglement structure, and the mechanical properties ofPC/PBT products depend on the crystalline of PBT.