PVT Characterization Of Homogeneous Systems With Supercritical Fluid Microfoam

The PVT properties of polymers are intrinsic properties of polymers and are essential for analysing the physical transformations that occur during polymer processing,and can be applied to predict the compatibility between multiple polymers,optimise process parameters,and regulate the quality of injection moulded products.Supercritical gas microfoam injection moulded products have the advantages of light weight and electromagnetic shielding,but compared to conventional injection moulding,micro foam products are more difficult to control in terms of dimensional stability and bubble structure.In this paper,the PVT characteristics of microfoam homogeneous system are studied to regulate the process parameters and product quality.The relationship between the PVT properties of microfoam homogeneous systems and the quality of microfoam products is the focus of this paper.This paper investigates the PVT characteristics of microfoam homogeneous system based on numerical simulation,reveals the influence of process parameters on the PVT characteristics of microfoam homogeneous system,and establishes the relationship between the variation of molding specific volume,pore structure and mechanical properties of the homogeneous system.1.Based on Moldex3D software,the moulding process of microfoam homogeneous system was simulated under different process parameters,and the influence of gas injection volume,injection speed and melt temperature on the PVT characteristics of microfoam homogeneous system was revealed.The results show that(1)increasing the gas injection rate increases the specific volume of the microfoamed homogeneous system and its sensitivity to temperature,but the transition temperature decreases,and the transition section of the semi-crystalline polymer microfoamed homogeneous system will be enlarged,which is caused by the free volume between the polymer chain segments occupied by gas molecules,and the molecular chain movement ability increases;(2)increasing the injection rate decreases the specific volume of the microfoamed homogeneous system,and the temperature sensitivity of the ABS homogeneous system is increased.(2)the increase in injection speed reduces the specific volume of the microfoam homogeneous system and increases the temperature sensitivity and transition temperature of the ABS homogeneous system,but the temperature sensitivity of the solid section of the PP homogeneous system decreases.(3)increasing the melt temperature increases the transition temperature of the microfoam homogeneous system and the specific volume of ABS,but the specific volume of PP homogeneous system decreases.2.The effect of the microfoam injection moulding process on the warping and deformation of the product and the microstructure morphology of the bubble hole was investigated by the orthogonal method,and the relationship between the change in specific volume of the product and the dimensional stability and quality of the bubble hole was established.The study shows that in order to produce the best quality microfoam plastic parts,the best specific volume increment of the simulated material is 0.0977cm3/g,and the comprehensive performance of warpage deformation and bubble structure of the simulated microfoam parts reaches the best,when the gas injection amount exceeds 2wt%,the specific volume increment is too large to form the bubble hole collapse bubble hole,and the specific volume increment when the gas injection amount is 1wt%is too small to make the cooling warpage deformation of the parts serious.3,Using a combination of numerical simulation and microfoam injection molding experiments,reveal the product molding specific volume and its change value on the bubble structure,mechanical properties of the law.The results show that the increase of gas injection volume makes the specific volume of micro-foamed parts increase,and small pores are formed inside the parts,and the fine pores reduce the loss of mechanical properties of the parts.The best specific volume increment of the experimental material is 0.111cm3/g,the distribution of the internal pores is uniform,the pore structure is good,and the tensile strength and impact strength of the parts are the best.