Advances blurring line between thermoplastics and thermosets

I arrived at my computer one day to find the following e-mail message: PLEASE CANCEL MY SUBSCRIPTION. I AM IN THE THERMOSET INDUSTRY AND YOUR MAGAZINE NEGLECTS US.

Having just published pieces about a thermoset material innovation and a new machine for injection molding of thermosets on our Technology Trends page, as well as a feature article on polyurethanes (our second in less than a year), I asked him to reconsider.

Still, I had to concede that, yes, our coverage of thermosets was minor in comparison to our coverage of thermoplastics. Admittedly, though, we have felt little guilt perpetuating this bias. After all, our excuse has been, thermoplastics is where all the action is these days. This observation seems especially true if one excludes polyurethanes, a thermoset and sometimes thermoplastic, albeit with its own unique properties and processing technology, which continues to be a widely-used workhorse in markets such as construction and automotive.

Rightly or not, many in the plastics trade-press profession have come to see thermosets as being synonymous with hand-layup molding and prepregs; the domain of either low-tech job shops or highly esoteric, low volume industries such as aerospace. This view is also shared by many in the plastics industry itself, where all the high-growth numbers and economies of scale are on the side of the engineering and commodity thermoplastics markets.

Yet, new technology, much of it already commercial, may demand that both the trade press and those in the business of making things out of plastic give thermosets more notice. The reason for this is because, in both its ability to be processed and recycled, thermosets are becoming more like thermoplastics.

As alluded to above, several machine manufacturers have recently introduced new injection molding machines for processing thermosets. Another company has brought to market an innovative glass-reinforced thermoset designed to be used with “soft” tooling in compression molding, replacing spray-up applications. (See Canadian Plastics, January 1999).

The agenda for the Industrial Materials Institute/National Research Council’s upcoming Polymer Technology Symposia offers more evidence of the on-going evolution of thermosets. A good chunk of the meeting (which takes place October 6-8 at Manoir du Lac Delage, Quebec) is devoted to new developments in processing and recycling thermoset materials. Certainly, if limitations in recyclability and processing are overcome, one can imagine more processors in mainstream markets such as automotive and consumer appliances considering thermosets in order to capitalize on the materials’ enhanced stiffness and other properties in certain applications.

But perhaps the bigger story here is the current commercial evolution of both classes of plastic materials. Just as there is a desire to make thermosets behave more like thermoplastics, there has been an interest for some time in expanding the applications of thermoplastics by, in effect, making them behave more like thermosets–for example recently announced efforts to extend the use of reinforced thermoplastics in automotive structural applications.

The meeting ground of the two trends, approaching from opposite ends of the plastics spectrum, is the broad area of advanced composites. Today advanced composites are used in commercial aircraft, marine and surface transportation, energy transmission and virtually every type of recreational equipment. Tomorrow, with the continued pace of innovation, we could see more molders with the ability to process these advanced materials, whether they’re thermoset- or thermoplastic-based, using similar forming equipment, to make parts for cars, computers and consumer appliances. When this happens, the two solitudes of plastics, thermosets and thermoplastics, will at last be one.

And at least one of our readers will be much happier.

e-mail: mlegault@southam.ca