Huntsman Advanced Materials has developed a new epoxy resin system and a new efficient process which could give an entirely new compression molding concept.
According to the company, the new compression molding process, which uses a fast-cure Araldite epoxy, makes it possible to make structural composite parts with cycle times as low as one minute without any further post-curing. It is also suitable for making structural parts using thermoset technology for high-volume applications such as automotive.
The company’s current system for high-volume manufacture of composite parts is the Araldite system used to make the BMW i-Series of cars. With a cure time of two minutes at 130°C, this system gives a total cycle time of around two minutes, 30 seconds. The latest rapid-cure Araldite epoxy system is quicker and also displays a higher Tg, enabling processing up to 150°C, and a cure time of just 30 seconds at 140°C. This means that at a press cycle time of only one minute is possible, without any further post-curing of the part. Following curing, the epoxy system displays a tensile elongation in excess of 5% with a Tg of 120°C.
Resin impregnation
Huntsman has also developed a dynamic fluid compression molding (DFCM) process to go with the new epoxy system. According to the company, the new process removes the need for high-pressure injection and in some cases, the need for a bonded fibre preform. The resin impregnation of the fibers through-thickness almost eradicates fiber-wash, a common problem with high-volume resin transfer molding (RTM) production parts, Huntsman says.
In tests carried out by the company, the new process reduced the void content of laminates in comparison to conventional wet-compression molding (WCM) process. It also allowed typical porosity content of less than 1%, making it comparable to high pressure RTM (HP RTM) or autoclave prepregs. Fiber volume contents of 66% can be achieved with no special processing conditions, while feavy-tow industrial fabrics proved similarly easy to impregnate, with virtually void-free parts, even when parts were made with a 960 gsm plain weave fabric.
This story uses material from Huntsman, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier.
