Four suppliers are bringing out higher-performance materials partly or wholly based on PLA biopolymer. For example, NatureWorks LLC, Minnetonka, Minn. (natureworksllc.com), is making a major capital investment at its Blair, Neb., facility to produce new high-performance grades of Ingeo PLA biopolymers. Samples will be available next year, and commercialization is expected by 2013. A new Ingeo grade for injection molding will offer faster cycle times. NatureWorks will also assess opportunities for these new grades in thermoforming, film extrusion, and stretch-blow molding.
•Another new, 100%-biobased product line is Bioloy PLA alloys for injection molding from Sukano Polymers Corp., Duncan, S.C. (sukano.ch) These custom-compounded products are PLA chemically grafted with additives to provide impact strength, durability, and easy processability.
•RTP Co., Winona, Minn. (rtpcompany.com), has introduced what it says are the first glass-reinforced PLA compounds, designed to overcome the limitations of unmodified PLA by providing greater strength, stiffness, and heat resistance. Grades are available with 10% to 40% glass. The 30%-glass grade has nearly twice the tensile strength and 200° F higher HDT than neat PLA. Its tensile strength is 16,500 psi, flexural modulus is 1.63 million psi, and HDT is 320 F at 66 psi. Special nucleation packages speed crystallization, which raises heat resistance and allows earlier part ejection, yielding PLA cycle times similar to PP and ABS.
•Teknor Apex Co., Pawtucket, R.I. (teknorapex.com), is also beefing up the properties of PLA-based compounds. Its new Terraloy BP-34001 series is compounded to provide up to twice the HDT and up to six times the impact strength of standard PLA. Previously, it was possible to enhance either the HDT or toughness of PLA, but not both, according to Teknor. A typical grade has a HDT of 112 C/233 F and Izod impact strength of 135 J/m (2.5 ft-lb/in.). The new materials are said to enable PLA to be used in a wider range of durable and semi-durable parts, as well as high-end disposable food-service items such as cutlery, coffee lids, and containers for microwaveable foods. In contrast with previous enhanced-performance PLA resins, the new compounds reportedly also have 28% to 30% shorter molding cycle times and 10% to 30% more renewable-source content. The new compounds meet FDA specs and have 78% renewable content. (See also Starting Up section.)
Editor Pick'Green'...And Microwaveable Too
New technology from Teknor Apex Co., Pawtucket, R.I., eliminates a property tradeoff that could allow polylactic acid (PLA) to supplant polystyrene and polypropylene for microwavable frozen-food trays, lids for hot beverage cups, and carry-out containers.