By Matt Griswold, Plastics NewsToronto, Canada -- Toronto-based pultrusion firm Inline Fiberglass Ltd. has introduced a new polyurethane-based fibreglass window profile - a technology that will revolutionise the window and door industry, company officials said.Common fibreglass windows today contain about 60 percent glass fibres and about 40 percent polyester resin, according to the company.Using Pittsburgh-based Bayer MaterialScience llc's new PU resin, Baydur PUL 2500, engineers at Inline have been able to increase the glass-fibre content to about 80 percent. The end result is a lighter, stronger, less-expensive window that requires no styrene to make, does not conduct hot or cold, and pultrudes faster than polyester, according to the company.Inline founder and chief engineer Stanley Rokicki said window makers have been quietly working on a PU-based fibreglass formula for the past decade."This is the biggest breakthrough," he said. "We have the first windows being made with PU. It's stronger than aluminium. It's the material of the future."Of all the emerging materials in the windows market, it is fibreglass that seems to be making the biggest strides, said Nick Limb, managing partner with Bloomfield Hills, Michigan-based Ducker Research Co. Inc."Fibreglass is a very strong material," Limb said. "That's probably the biggest differentiator. But it's an expensive material, a premium product. They're going to have to change the cost structure as the material develops."Inline officials are in the midst of converting all of their pultrusion lines to the new urethane blend, eventually eliminating polyester from their product line. Since PU is easier to process than polyester, the company has not had to invest heavily in new tooling."