Effects of Injection Molding Parameters on Properties of Insert-Injection Molded Polypropylene Single-Polymer Composites

Abstract

The reinforcement and matrix of a polymer material can be composited into a single polymer composite (SPC), which is light weight, high strength, and has easy recyclability. The insert injection molding process can be used to realize the multiple production of SPC products with a short cycle time and wide processing temperature window. However, injection molding is a very complicated process; the influence of several important parameters should be determined to help in the future tailoring of SPCs to specific applications. The effects of varying barrel temperature, injection pressure, injection speed, and holding time on the properties of the insert-injection molded polypropylene (PP) SPC parts were investigated. It was found that the sample weight and tensile properties of the PP SPCs varied in different rules with the variations of these four parameters. The barrel temperature has a significant effect, followed by the holding time and injection pressure. Suitable parameter values should be determined for enhanced mechanical properties. Based on the tensile strength, a barrel temperature of 260 °C, an injection pressure of 127.6 MPa, an injection speed of 0.18 m/s, and a holding time of 60 s were determined as the optimum processing conditions. The best tensile strength and peel strength were up to 120 MPa and 19.44 N/cm, respectively.

Fabric Insert Injection Molding for the Preparation of Ultra-High Molecular Weight Polyethylene/High-Density Polyethylene Two-Component Self-Reinforced Composites

“… Schematics of the mold cavity and the fabric insert injection molding structure of the UHMWPE/HDPE SrC sample ( a ) and pictures of the mold plate, fabric, and the tensile SrC sample ( b ) [ 28 ]. …”

“…Some continuous manufacturing processes, such as extrusion-calendaring [ 22 , 23 ] and double belt pressing [ 24 , 25 ], have been also developed for the industrial production of SrC laminates or prepregs, which are generally intermediate materials. Whereas insert injection molding has been applied to produce SrC parts [ 26 , 27 , 28 ], complex shape and short cycle time can be realized. Good interfacial bonding between the inserted fabrics and the polymer melt can be realized due to the same polymer material.…”

Direct In-Mold Impregnation of Glass Fiber Fabric by Polypropylene with Supercritical Nitrogen in Microcellular Injection Molding Process

“…Therefore, the chosen preparation process for prepregs affects the molding cycle and increases energy consumption [ 11 , 12 , 13 ]. Wang et al [ 14 ] proposed a successful method that can realize the production of single-polymer composites whose matrix and fiber reinforcement are from the same polymer. They directly set the fabrics as an insert in the mold cavity and then applied the insert injection molding process.…”

“…They directly set the fabrics as an insert in the mold cavity and then applied the insert injection molding process. The influences of the injection molding process parameters, including the temperature, pressure, and time, were especially discussed [ 14 ]. Moreover, in order to improve the permeability, they presented an insert injection molding method whereby the inserted fabric was fixed in the middle of the mold cavity using clamping force [ 15 ].…”

Investigations on Temperatures of the Flat Insert Mold Cavity Using VCRHCS with CFD Simulation

“…The plastic cools and solidifies to make a product. In the injection molding process, the plastic flows in a laminar flow, and the melt front fills the mold cavity in the form of a fountain flow [ 14 , 15 ]. The fountain flow allows the plastic to gradually solidify from the contact side of the mold wall to the center layer of the plastic [ 16 ].…”