Deformation and Simulation of the Cellular Structure of Foamed Polypropylene Composites

Foamed Polymer is an important polymer material, which is one of the most widely used polymer materials and plays a very important role in the polymer industry. In this work, foamed polypropylene (PP) composites are prepared by injection molding, and the cell deformation process within them is studied by combining visualization technology and COMSOL software simulation. The results shows that the deformation of isolated cells depends in temperature, and there is no macroscopic deformation. There was no significant difference between the stress around adjacent cells at different temperatures, but the stress at different positions around the adjacent cells has obvious changes, and the maximum stress at the center of the adjacent cells was 224.18 N·m−2, which was easy to cause a lateral deformation of the cells. With the increase in temperature, the displacement around the adjacent cell gradually increased, the maximum displacement of the upper and lower symmetrical points of the cell was 14.62 μm, which is most likely to cause longitudinal deformation of the cell; the deviation of the cell deformation parameter gradually increased, which led to deformation during the growth of the cell easily. The simulation results were consistent with the visualized cell deformation behaviors of the foamed PP composites

The Effect of α-Olefin–Maleic Anhydride Copolymer on the Rheological and Crystalline Properties and Microcellular Foaming Behavior of Polyamide 6

The α-olefin–maleic anhydride copolymer DIA as a chain extender was used to modify polyamide 6 (PA6) during melt blending. The ability to modulate this modification for PA6 has been shown to be dependent on the effects of its content on the molecular weight distribution, rheological properties, crystalline properties, mechanical properties, and foaming behavior of foam samples. By increasing the DIA content, the viscoelasticity, water contact angle, and elongation at break improved as a result of a significant decrease in water absorption and melt flow rate. Compared with raw PA6, the modified PA6 presented a relatively wider molecular weight distribution. However, the crystallinity of modified PA6 samples decreased, the double melting peaks became one peak, and the α crystallites at 20.3° gradually disappeared with increasing DIA content. The morphologies of composite foams with different contents were analyzed using scanning electron microscopy. It was found that the cell size of different PA6 samples decreased from 160 μm to 83 μm and the cell density increased from 1.1 × 105 cells/cm3 to 5.9 × 105 cells/cm3 when the content of DIA increased from 0 wt% to 5 wt%. Meanwhile, the cell morphology obviously improved and the cell size distribution became narrow. Thus, a preparation technology based on foaming materials with excellent performance, such as better bubble quality and low water absorption, was developed for further research and application

Experimental and simulation analysis of bubble deformation in foaming polypropylene

This paper investigates the bubble deformation in bubble growth using a self-made in situ visual injection molding device. The results show that the deformation degree of independent bubbles is kept within 0.015. Under the frame rate of 25 frames per second (FPS), it is found that adjacent bubbles with the same average diameter simultaneously pass through the deformation critical point, while adjacent bubbles with different average diameters can’t pass through the critical deformation point at the same time. The interaction in the process of adjacent bubble growth is simulated by finite element software, radial migration of bubbles is suppressed, the hoop stretch of bubbles is enhanced, and the deformation sequence of adjacent bubbles is determined by bubble radius and bubble pressure. On the basis of the bubble influence zone model and the bubble deformation model, a bubble deformation response model is established, used to reflect adjacent bubbles’ deformation response speed