Polystyrene Foam with High Cell Density and Small Cell Size by Compression‐Injection Molding and Core Back Foaming Technique: Evolution of Cells in Cavity

Abstract

Many efforts have been made to obtain uniform cell structures from foam injection molding techniques. However, cell nucleation mechanism and complex dynamics during the cell formation have rarely been well understood. Here, high‐pressure foam injection molding (HPFIM) is achieved by combining the injection–compression molding with core back foaming (ICMCBF) technique. The influences of compression pressure and time on the cell structure of polystyrene foam during the foaming process are studied. Compared with low pressure for conventional foam injection molding, high compression pressure (200 bar) and fast pressure drop rate of ICMCBF endow the foam with the highest cell density (1.59 × 107 cells cm−3), and the smallest cell size (15 µm). The tensile strength and impact strength are enhanced by about 60% (from 22.3 to 35.6 MPa) and 80% (from 3.6 to 6.8 MPa), respectively. This study gives a critical understanding of the cell nucleation and growth mechanism of the foam injection molding and supplies a new strategy for the fabrication of foam with uniform cell structure.

Fabrication of fibrillated and interconnected porous poly(ε-caprolactone) vascular tissue engineering scaffolds by microcellular foaming and polymer leaching

“…The device stiffness and strength are important characteristics that dene the interface with existing tissue and the pressure tolerance of the vascular scaffolds. 41,42 Fig. 11(a) shows that the longitudinal strength and modulus of foamed PCL70 was bigger than that of PCL50.…”

Electromagnetic Shielding by MXene-Graphene-PVDF Composite with Hydrophobic, Lightweight and Flexible Graphene Coated Fabric

“…The cross links improve the thermo mechanical properties [ 26 , 27 , 28 ]. Furthermore, in the polymer foams the voids form due to the different nucleation time of constitutional solid and other external factor like temperature pressure [ 29 ]. Advanced EMI shielding materials should be lightweight, flexible, cost effective, dielectric, and multifunctional, and should possess a tunable absorption, high thermal resistance, intrinsic conductivity, large aspect ratio, high corrosion resistance, and good magnetic and electronic properties [ 19 , 20 , 30 , 31 , 32 , 33 , 34 ].…”

Improvement of the dispersity of micro‐nano particles for PP/PVC composites using gas‐assisted dispersion in a controlled foaming process

“…a, an expected imperfect foam structure of neat PP resin with a cell density of 5.7 × 10 5 cells/cm 3 and an average cell size of 51.9 μm can be observed from the SEM micrographs. It is not easy to manufacture a foamed neat PP sample with a cell density of 10 6 cells/cm 3 using a conventional injection molding machine . The cell size and cell density of neat PP resin, as shown in Fig.…”