GE Plastics’ pledge to develop environmentally-friendly materials is starting to bear fruit. The company has developed new PBT-based resins and polyester-based elastomers whose feedstocks come partially from post-consumer waste.
To make these materials, GE uses a proprietary manufacturing technology that transforms post-consumer PET – mostly from bottles – into one of the chemical building blocks of PBT. According to Vikram Gopal, the company’s program manager for crystalline plastics, GE first depolymerizes the PET and then chemically “upgrades” it so that it can be reacted with BDO to produce PBT. “What we’ve been able to do is use this post-consumer feedstock to replace DMT or TPA, the feedstocks used in the two conventional PBT processes,” he explains. In all, more than 85 percent of the PBT’s usual feedstocks are replaced by the feedstock derived from post-consumer waste.
The environmental benefits of incorporating so much post-consumer waste add up quickly. According to calculations GE made as part of an environmental analysis of the new materials, iQ technology reduces CO2 emissions by at least 1.7 kg per kg of resin and saves up to 8.5 barrels of crude oil per 1,000 kg of resin. “If all PBT was made using GE’s Valox iQ resin technology, it would represent an annual reduction of 1.4 million metric tons of CO2 emissions. This is equivalent to planting a forest 650 square kilometers in an area which is greater than the area of metro Tokyo,” says Nicholas Eisenberger, managing principal of GreenOrder, an environmental strategy firm that audited GE’s environmental assessments of the new PBT materials and helps qualify GE’s other Ecomagination products.
And in the future, these green materials may grow even greener. Gopal says GE is at work developing bio-based feedstocks for BDO, the other key ingredient in PBT.
GE will initially offer six materials based on this new process technology, which it calls “iQ.” The company will offer four varieties of Valox iQ PBT materials – filled, unfilled, flame-retardant and lighting-bezel grades. And it will offer two unfilled Xenoy iQ PBT-PC alloys – one tailored to automotive energy absorbers and another to general-purpose applications.
Property-wise, all of the new iQ materials very closely duplicate the performance of their conventional counterparts. “They’re drop-in replacements that meet existing specifications,” says Gopal. The new PBT grades do have a small loss of heat resistance with an HDT that’s about 5C lower than conventional PBT – though GE can modify the grades to increase the HDT if the application requires it. On the plus side, the iQ PBTs flow 10 to 20 percent better than conventional PBTs. Gopal believes the flow improvements have the potential to enable thinner wall sections, improve cycle times and lower temperature processing – especially if the iQ technology is combined with an unrelated high-flow technology that GE previously developed for its conventional Valox PBT resins.
All of the new PBT-based materials are now available globally for sampling. The focus for the first of the new materials is automotive applications, including connectors, lighting components, energy absorbers and more. Japanese components supplier DENSO is one of the first companies to evaluate the new materials, says Tim Dummer, GE’s director for new automotive markets. “The goal is to bring the technology to automotive users first but then apply it to a broad spectrum of applications that consume PBT,” Dummer says.
And GE isn’t stopping with PBT thermoplastics. The company has also developed polyester-based elastomers derived from iQ-like technology. According to Gopal, the elastomers will come in Shore D hardnesses and perform over a wide temperature range – from -60 to 200C. Depending on the formulation, the elongations will range from as little as 90 percent to about 500 percent, he adds. These thermoplastic elastomers are scheduled for commercial release sometime in 2007.
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