Polymer Static Shear Crystallization Experiments And Calculation Of Preliminary Research

Crystal structure is one kind of aggregation structure, the behavior and performance of polymer parts are mainly determined by its processing namely structuring. The crystallization in processing has a great influence on product's properties. The main results focusing on polymer crystallization are as follow:1. Research on crystallization kinetics of iPP has been done, crystallization kinetics parameters are worked out by the means of nonisothermal crystallization kinetics function;2. Research on the shear-induced crystallization of iPP has been done under isothermal and nonisothermal conditions. The DSC results under the same temperature conditions are compared with the results from Rheometer respectively.. The comparison demonstrates that shear contributes to crystallization of polymer. Because of the aggregation structure's response to frequency, frequency shows greater effect on crystallization in latter period than that in the earlier one; The relative crystallinity will increase as the Gap's value decreases; Due to the crystal nucleus mechanism, small strain has less influence on relative crystallinity in earlier period than the large one, but reversely in latter period; The shear-induced relative crystallinity is greater than the one in steady state if they are in the same temperature condition;3. Temperature is calculated between the end of injection and the end of packing with Fourier unsteady thermal conductive equation on the premise that the heat of crystallization is regarded as the inner heat source. Specific heat is regarded as the function of temperature. Then specific heat temperature-equation is introduced into Z-mold's original codes. Only considering the heat of crystallization, the specific heat and not considering the both parameters respectively, the calculated results gained from such conditions are compared. The comparison demonstrates that heat of crystallization can influence the temperature field greatly, so that heat of crystallization must be considered in injection modeling. Specific heat has little influence on the temperature field which may be the reason why specific heat is not regarded as a variable in many sophisticated injection modeling CAE programs;4. The nonisothermal crystallization experiments are done firstly. Then heat of crystallization at different cooling rates are fitted. Lastly, the crysatllinity at different positions of product is calculated. Though different crystallinity calculated method has different meanings, crystallinity gained from the same method can play great role in valuing properties;...