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01 | 2010

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Cellulosics

Foam Article contributed

Foam Article contributed by William Kelly, VP Technology and Gary Larrivee, VP Technical Support Cereplast, Inc., Hawthorne, California, USA A True Compostable Foam Cereplast Compostable 5001 ® is perfectly suited to meet the needs of all converters, manufacturers and brand owners interested in substituting Polystyrene foam with an environmentally sustainable plastic. Cereplast Compostable 5001 is a compostable foam using Ingeo PLA and various biodegradable and compostable components. Currently PLA based polymers are the dominant resin in the biopolymer industry from a technology and supply standpoint. The market for expanded polystyrene is greater than five billion dollars per year in the USA. With cities and counties banning the use of polystyrene packaging consumers are demanding alternative products. What is attractive about using a Cereplast foam polymer is that the finished products can biodegrade in 180 days or less in a commercial compost facility. Many disposable products are made of low density polystyrene foam materials. These foam products however will not biodegrade, even when filled with starch. Degradation of the starch will not cause the polystyrene to degrade and all the ‘additive’ technology has not been scientifically proven, nor demonstrated. Many of the applications that exist in polystyrene based foam materials are suitable for Cereplast Compostable materials such as clam shell food containers, meat trays, egg cartons, mushroom and berry boxes and a variety of packaging applications. Densities down to 0.08 g/cm 3 using conventional equipment were achieved and Cereplast is continuing research to further reduce densities. These products have the same look and feel as the polystyrene foam parts that they are replacing. There is no Bisphenol A (BPA) or any other harmful compounds found in Cereplast 5001. From a technical standpoint, it is difficult to produce from an unmodified PLA a viable foam product. In order to produce low density foam PLA based resins the polymer must be modified to increase molecular weight and elasticity. Increasing intrinsic viscosity and melt strength is also key to producing a good foam product. One method to increase melt elasticity and molecular weight is to utilize chain extenders associated to the end groups of PLA. Increases in melt elasticity and molecular weight result in producing foams with reduced cell size, increased cell density and lowered bulk foam density when compared to unmodified PLA foam. Cereplast specialty is to modify Ingeo PLA manufactured by NatureWorks. Cereplast Compostables 5001 represents an outstanding opportunity for companies across the plastic supply chain used to foam plastic resins and are seeking to become more environmentally sustainable and reduce the industry’s reliance on oil. Cereplast Compostable 5001 is the successful result of a several years research and development project which answers the growing demand for more sustainability from the plastic industry. www.cereplast.com 32 bioplastics MAGAZINE [01/10] Vol. 5

Materials High Heat Injection Molding PLA On January 14, NatureWorks LLC introduced its second generation Ingeo bioresin (PLA) solution targeted primarily at injection molding of semi-durable consumer products. This new patent-pending solution is the latest in a series of breakthroughs for Ingeo applications, which already include high heat thermoforms, films, and gift and transactional cards. NatureWorks’ new compounded resin technology enables the production of injection molded parts with a heat deflection temperature of up to 140°C (modified version of ASTM E2092) or 65°C (HDT B), notched Izod impact strength greater than 140 J/m, and modulus of about 3,000 MPa. “Different formulations based on this new development, with a reduced amount of impact modifier will lead to HDT B values of up to 140°C,” explained Jed Randall, Research Scientist at NatureWorks. Injection molding cycle time compares to styrenic resins, for which the new technology now offers a low-carbon, cost-competitive, performance replacement. Designated Ingeo 3801X, the new formulation combines a high percentage polylactide base resin with a tailored additive package designed to achieve the high heat, impact, and cycle time performance requirements of semi-durable products such as cosmetics, consumer electronics, toys, office accessories, and promotional products. “The introduction of this high heat technology demonstrates that the Ingeo family is maturing significantly, steadily broadening into a host of applications where these materials are a performance substitute for non-renewably sourced plastics,” said Marc Verbruggen, president and CEO of NatureWorks. “In the six years since we entered the market with our world-scale facility, the injection molding community has shown significant interest in our first generation product. The industry has already developed a compelling array of injection molded consumer products, with items that include lipsticks and compacts, mobile phones, and auto interior parts. Today, we’re pleased to announce support for ongoing development efforts with a product that has been custom designed to address enhanced property and performance requests.” NatureWorks is selectively opening this proprietary technology to Ingeo compounding partners, as Verbruggen explains. “NatureWorks firmly believes that the continuing development of Ingeo solutions for durable applications is best complemented by the innovations, expertise, and capabilities that our compounding partners offer.” www.natureworksllc.com A Novel, Lightweight, Heat-resistant PLA Among the most significant challenges for the wider application of PLA is its low heat resistance: native PLA usually turns soft at around 60 ºC, which not only makes it incapable of holding heated food or a hot drink, but also causes deformation during container transport. Enhancement of the heat resistance of PLA has been achieved already by adding fillers, or mixing with hard plastics. However these treatments often have unfavorable consequences such as an increase in density and difficulties in recycling. In the case of semi crystalline plastics adding nucleating agents is another approach, however for PLA, which crystallizes at a rather slow rate, such treatment does not bring about a significant improvement in heat resistance. By means of novel recipes and process equipments, Supla Co. Ltd. of Taiwan have developed SUPLA C that has a unique crystallization behavior, which results in a high HDT at around 100ºC (HDT B 120°C/hr, 0.45 MPa). Furthermore, because not much fillers were added, the density was kept at a level almost equivalent to native PLA. This lightweight characteristic results in a higher Melt Flow Rate of 31.9 g/10min (190ºC, 2.16 kg), which makes Supla C advantageous over other types of modified PLA in injection molding. Besides, the products would be lighter, so it is energy saving during transportation of the moulded products. Supla C minimizes the difficulties in forthcoming challenges towards recycling of PLA products, because in general, recycling of composite materials is more difficult than that of pure, homogeneous materials. PLAs with superior heat resistance have potential markets such as food wares, stationery, gifts, toys, 3C housing (3C = computer, communication and consumer electronics) etc. Supla C is suitable for all of the above applications, and is expected to exhibit particular strength in thin wall housing which is the mainstream in the design of 3C goods. supla.com@msa.hinet.net bioplastics MAGAZINE [01/10] Vol. 5 33

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