Thermal expansion of high‐density polyethylene in hot plate welding applications

Abstract

This research studies high‐density polyethylene (HDPE) behavior that is not easily identifiable in a production setting, but is, nevertheless, necessary for consideration when specifying equipment performance for hot plate welding (HPW) applications. Thermal expansion in polymers can depend on several factors, such as the specific type of polymer, its degree of cross‐linking, and the temperature range over which the expansion occurs. This physical behavior can affect the process by prolonging the cycle time if the equipment is not sized correctly for the application. This research uses HDPE samples with different surface areas and varying process parameters (force and temperature) to collect data on the sample size change. Experimental results are compared with a recommended industrial guideline of 0.2 to 0.5 MPa of pressure for the Matching stage (stage for surface conformation). Obtained findings indicate that this industrial guideline is very temperature dependent. Data collected in the experiment were used to develop a mathematical model for thermal expansion under different parameters. This study also presents a visual interpretation of HDPE behavior on the effect of temperature if the pressure is increased or decreased.

Computational and experimental study on the resistance welding process of a glass fiber‐reinforced epoxy‐based composite with thermoplastic interlayer adherent

“…It usually consists of the following steps: heating up the weld line to above either the glass transition temperature (T g ) for amorphous or the melting temperature (T m ) for crystalline/semi‐crystalline thermoplastics with a proper pressure applied during diffusion of molecules and consolidation of joint; Cooling down to the room temperature to solidify the polymer. Depending on the heating source, different welding approaches have been reported, including hot‐press welding, 8–10 ultrasonic signal welding, 11–13 laser welding, 14,15 induction welding 16 and resistance welding 17 . Although they are faster than the adhesive bonding, most of them are either high‐cost or limited to bond large‐scale components, such as the laser and the ultrasonic welding 11,12 .…”

Preparation of fluorinated poly(aryl ether) with high dimensional stability and high temperature resistance by photo‐thermal dual crosslinking reaction

“…Dimensional stability is an important parameter that should be considered for polymers in practical processing scenarios. FPAE, as a class of material with great potential for applications in semiconductor fabrication, communication technology and intelligent manufacturing technology, should be emphasized for their dimensional stability 11–14 . In recent years, for the study of dimensional stability, zero expansion or even negative thermal expansion materials have attracted the wide attention of researchers.…”