Morphology of Fluid Assisted Injection Molded Polycarbonate/Polyethylene Blends

Abstract

This study aims to examine the morphological development in fluid assisted injection molded high density polyethylene (HDPE)/polycarbonate (PC) blends. Samples for microscopic observation were prepared by an 80‐ton injection‐molding machine equipped with a tube cavity and with both gas and water injection units. It was observed that the shape and size of the dispersed phase depended on the position both across the part thickness and along the flow direction. Water molded parts with a smaller PC particle distribution than gas. Additionally, high fluid pressures were found to mold parts with a smaller PC particle distribution. For both gas and water assisted injection molding, small and large particles coexisted in the skin and subskin layers, indicating that both coalescence and breakup of the dispersed phase occurred in that layer.magnified image

Overview of the Experimental Trends in Water‐Assisted Injection Molding

“…The samples taken from the outer layer, middle layer, and inner layer showed a similar melting peak and crystallinity at position near the end of water channel. Liu et al found that material at the mold‐side exhibited a higher degree of crystallinity than that at the water‐side, and the crystallinity at the water‐side layer increased with increasing the water temperature, which was consistent with the reported results . In addition, for the WAIM–molded nylon 6 (PA6) parts, it was found that the γ‐phase crystals and α‐phase crystals, respectively, dominated the crystal morphology at the skin and intermediate layers, but the coexistence of the γ‐ and the α‐phase crystals dominated at the water‐channel layer…”

“…Wang and Huang suggested that lowering the melt temperature is favorable for the formation of β‐form in the WAIM PP part ( Figure a,b). However, Lin and Liu reported that no β‐form was found in the WAIM part, but a larger amount in the CIM part. They explained that this phenomenon was attributed to fast solidifying rate brought by the injected water that left short time for the growth of the β‐phase on the formed α‐row nuclei.…”

“…The results showed that the WAIM part was characterized with a distinct skin–core–water channel structure through the thickness, including a shish‐kebab structured skin, a typically spherulitic core, and a shish structure with low oriented lamellar water channel region (see Figure ). A distinct skin–core–water channel structure was also observed . Zheng and co‐workers studied the orientation and morphology of pure isotactic polypropylene (iPP) and nucleated iPP molded by WAIM.…”

“…This review focused on the WAIM equipment and the water penetration behavior and simulation, but it did not provide the experimental trends on WAIM. Furthermore, there have been investigations on the morphology and orientation evolution of the WAIM parts recently . Therefore, the present review article aims to review and summarize current research in WAIM, focusing on experimental trends in computer simulation, the effect of processing parameters, morphology and orientation, fiber‐filled thermoplastic composites, as well as the polymer blends.…”

Experimental study of penetration interfaces in the overflow fluid-assisted co-injection molding process

“…FAIM can enable greater freedom of design, material savings, weight reduction, and cost savings in tooling and press capacity requirements [4]. CIM can be used to produce parts with special characteristics by the combination of two or more types of plastic materials, such as using the outer material to achieve required surface properties, while using the core material to obtain sufficient mechanical properties or to reduce cost [7,8].…”