sustainability | Bioplastics
expect to use a material like this, which is nascent and has no volume, and compete with something like PC/ ABS,” he said. The environmental aspects of PLA are widely
acknowledged today. The polymer’s big weakness has been its low softening point. That is now being addressed both through compounded blends and base polymer chemistry. Natureworks’ director of durables and distribution
Above: Corbion, formerly Purac, claims the ability to produce high purity L and D isomers is key in making PLA a more durable polymer
but it is essential that any benefi ts the company claims are genuine and can be validated. “No greenwashing,” he said. “We want to be certain that the material we use really does deliver a sustainable benefi t.” Kuzcynski said the company has spent around a
year working on a project to replace some of the approximately 2,700 tonnes of PC/ABS blends it uses each year with a PC/PLA alternative for production of injection moulded enclosure parts. This new blend is expected to go into production on the company’s BladeCenter line of servers during this year. Meeting or getting very close to the mechanical
performance of the original PC/ABS parts with PC/PLA blends containing 30-40% PLA was not too diffi cult a task, he said, with only a slight relaxation required in terms of HDT and impact required. However, meeting the UL V-0 fl ammability rating at 1.6mm required in the computer industry was a challenge. “Simply blending in commercial FR packages proved to be insuffi cient,” he said. Kuzcynski said the fl ame retardance system fi nally
selected adds to the already higher cost of the PC/PLA compound. However, the premium is manageable given that the enclosure components are a minor contributor to the overall cost of a server system. “You cannot
Frank Diodato said that development partners such as specialist compounder Teknor Apex have been able to modify its PLA products to develop compounds such as Terraloy BP34001D, which offers a bio-based content of 90% and a HDT value of 112˚C, compared with 55˚C for the company’s Ingeo 3251D high fl ow injection moulding grade of PLA. Notched Izod impact performance is also dramatically increased, up to 133 J/m against 16 J/m for the standard product. Diadato said Natureworks is also commercialising its Ingeo HP products, which use optimisation of molecular weight and d-isomer content in the polymer to provide improved crystallisation rates and modulus above the glass transition temperature. To date, commercial Ingeo grades have had a d-isomer content of more than 1.5%; the HP grades reduce this to less than 0.5%. This, together with a special nucleation package, helps speed up crystallisation to improve thermal properties and reduce injection moulding cycle times. The company is completing modifi cations to its
140,000 tonne/year plant in Nebraska in the US in preparation for imminent production start-up of the new HP grades, he said. The fi rst products will target
Figure 2: Bioplastics production capacity by type 2016 Source: European Bioplastics/IfBB
36 INJECTION WORLD | July/August 2013
Figure 1: Global production capacity of bioplastics Source: European Bioplastics/IfBB
www.injectionworld.com
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