Microcellular Injection Molding of PP and PC/ABS with Precision Mold Opening and Gas Counterpressure

Abstract

The injection molding of microcellular polymers is expected to be increasable promise for engineering applications. The combined effect of precision mold opening and gas counterpressure process produced uniform microfoam structure with a maximal cell diameter less than 10 μm/1/. The nature of microcellular PP and PC/ABS was analyzed. It was observed that the mechanical properties, the morphology and the application of microcellular PP were influenced by the degree of crystallinity and the conditions of foaming process. The viscoelastic behavior of materials and their correlation between process, foam structure and properties of PP foam and PC/ABS foam were investigated by DMA.

Polymer foaming with chemical blowing agents: Experiment and modeling

“…In all the cases, the percentages represent the weight concentration respect to PE matrix. In the following, CBA refers to the compound and not to the reactive elements only [16][17][18][19][20].…”

Lightweight Medium-Sized Parts Made of Foamed HDPE Processed via Extrusion Blow Moulding: Analysis of Parison Formation

“…Parisons with no CFA show less swell, are more viscous, and thus dissipate less irreversible energy due to their springy behaviour. The speed at which the parison is pushed not only affects diameter swell but also affects its shrinkage due to the fact that the molten polymer remaining in the die is shorter and therefore it has a shorter relaxation time which makes the degree of elastic strain recovery greater [26]. Results show that the perimeter becomes 42% bigger ( Figure 6) when adding 2 wt.% of CFA with respect to nonfoamed HDPE.…”

Characterization of the Structure, Acoustic Property, Thermal Conductivity, and Mechanical Property of Highly Expanded Open‐Cell Polycarbonate Foams

“…Then, the polymer/gas mixture was injected into it while the GCP was maintained. The mold cavity was completely filled by a full shot, and the foam expansion was achieved by opening the mold . The mold cavity pressures were measured at three different locations, i.e., near the gate, in the middle of the cavity, and near the end of the cavity during the entire injection cycle, using three PT462E Dynisco pressure transducers and a DAQ board (Compact DAQ Kit, National Instruments).…”

“…These foams were greatly expanded, and the cells were interconnected by pin‐holes on the cell walls . To produce them, we combined the regular foam injection‐molding process with mold opening and gas counter‐pressure (GCP) technologies. We believe that cell opening was achieved through the following three mechanisms: (i) large expansion (thinner cell walls), (ii) application of a shear motion (because of the edge effect), and (iii) by the tensile stress added by the mold opening and the biaxial stretching from cell growth.…”