These composites have a combination of desired thermal properties and performance characteristics that enable use in building and construction applications as well as other markets where these combined characteristics offer improved performance over traditional products and materials. The developed thermoplastic composites offer exceptional thermal properties and impact-resistance for such applications as siding, railing, dark coloured fencing and window parts.

Engineering long-glass composites for siding performance

After starting to study the development of a new class of siding in 2023, GaMra realised that this material would not only be suitable for siding, but could also be used in many other products. Thanks to its knowledge of the existing siding industry and its extensive experience in improving the properties of thermoplastics, the company was able to develop a thermoplastic-based siding that could compete with products such as fibre cement (James Hardie) and oriented strand board (LP SmartSide). To be truly competitive, GaMra decided to manufacture a product that could be ‘hard nailed’, available in 16-foot-long (488 cm) panels, lightweight (easy to install/move by a single installer), with good impact properties, a Heat Deflection Temperature (HDT) above 200°F (93.3°C), good weather resistance, and, ideally, the ability to be used in ground contact situations where existing materials cannot be used. And all this at a reasonable cost.

One of its most important attributes of GaMra’s siding is that it is capable of being fastened by ‘hard nailing’. “We used the ancient Euler equation for column buckling to guide us toward specific coefficient of thermal expansion (COTE) goals,” said Greg Mitsch, GaMra Founder and CEO. GaMra started out with a small strip die to begin the screening process and looked at a variety of resins including PVC, Polystyrene, PP, PE, ABS, Polycarbonate and researched various methods to reduce the COTE of these materials to the target value. The result of GaMra’s development efforts is a siding material that can be hard nailed like any wood siding, cement board or oriented strand board, is lightweight and strong enough to be handled, in 16’ (488 cm) lengths, by one person, cuts and drills with standard wood-working tools, resists winds up to 170 mph (274 km/h), remains undeformed at temperatures up to 250°F (121°C), is undamaged by 2” (5 cm) hail stones, can be used in ground-contact applications and can be recycled.

The extruded siding product is composed of about 40 wt% long-glass fibre and 60 wt% polypropylene co-polymers. Its density has been reduced to about half that of an unmodified composite.

“I’m not aware of anyone who is extruding long-glass composites,” stated Mitsch. “Most applications for long-glass are injection- or compression-moulded. We developed a proprietary extrusion process to make our unique siding.” With an in-house tooling shop at its disposal, custom tooling was produced and process experimentation was greatly accelerated.

Performance testing and weatherability development

In addition, GaMra has a force of talented and experienced engineers, who developed test equipment for analysing the performance and durability of siding products, including:

Siding products are co-extruded with a weatherable polyolefin compositions capping at a thickness of about .015” (0,04 cm). This coextruded capping material gives a superior finish that is weatherable and far superior to paint. “Over a year ago, we initiated outdoor exposures, intended to examine the effects of both direct and reflected sunlight on our product. In addition, we are measuring product temperature at various locations on these exposures on a minute-by-minute basis,” Mitsch said. “We believe it’s important to expose our product, not only to direct southern sunlight, but also to indirect heating sources like adjoining windows and garage roofs.” GaMra’s outdoor exposures are located in Hudson, WI and Cave Creek, AZ.

GaMra currently has two US patent applications surrounding its work to date.

about GaMra Composites

GaMra Composites, located in Hudson, Wisconsin, is a company specialising in plastic profile extrusion founded over 25 years ago by Greg Mitsch, its current CEO and owner, and Mike May, its previous technical director. During the company’s 25-year history, GaMra has extruded many different resins, including PVC, polyethylene, polypropylene, ASA, polycarbonate, thermoplastic elastomers, ABS and even PEEK (polyetheretherketone) at one point. GaMra currently serves five different markets (residential fenestration, pipe mandrels, windows, commercial fenestration and energy management) and has an extensive tooling shop to manufacture all of its own tools.