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Issue 03/2015

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  • Bioplastics
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  • Injection
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Injection Moulding New

Injection Moulding New PLA formulations to replace ABS NatureWorks (Minnetonka, Minnesota, USA) announced in late April the availability of new ABS replacement formulations that clearly demonstrate PLA based Ingeo resins have evolved into a practical and safe alternative for a broad range of styrenics in terms of performance, price, and eco profile. Three new formulated Ingeo injection molding offerings built on NatureWorks’ heat-stable technology platform offer a range of impact and modulus performance features in tandem with excellent chemical resistance. Two formulations offer medium and high impact performance with high bio content, making them ideal for injection molding applications – particularly those currently utilizing ABS. Additionally, a high modulus Ingeo formulation for profile extrusion applications maintains excellent impact performance and, just as with the injection molding offerings, this formulation’s high stiffness (up to 50 % higher flex modulus vs. ABS) offers opportunities for downgauging and materials savings. “Our new Ingeo formulations take factors like thermal performance as a given and move beyond that to offer a comprehensive suite of properties, which in some cases exceed ABS,” said Frank Diodato, who leads NatureWorks Durables Business platform. “Compared to ABS, these Ingeo formulations also offer significantly improved resistance to many common household chemicals – including spray and wipe cleaning agents, oils, and common personal care products such as nail polish remover, sunscreen and hand sanitizer. Diodato explained that unlike legacy polymer blend approaches that often alloyed or compounded PLA with a petroleum-based polymer to achieve requisite properties, although at a reduced biobased content, these new Ingeo formulations derive their functionality from the crystallization enabled by combining NatureWorks’ newly commercialized polymer chemistries. The resulting Ingeo formulation has a renewably sourced carbon content of approximately 90 %. The new Ingeo grades possess significantly faster crystallization kinetics than conventional PLA resins currently in the market place. The rapid crystallization rate leads to high heat distortion temperatures of up to 92 °C (HDT B @ 0.46 MPa). The fast crystallization also allows for the molding of crystalline parts at significantly faster cycle times than legacy products in the market. Excellent chemical resistance vs. ABS ESCR performance Solvent/chemical Ingeo medium impact formulation (884-41-1) Ingeo high impact formulation (884-41-2) 1 hour 24 hours 96 hours 1 hour 24 hours 96 hours 1 hour 24 hours 96 hours ABS None Distilled vinegar (5 % acidity) Isopropanol Ajax spray & wipe cleaner Dawn liquid dish soap Bertolli extra virgin olive oil Unsalted butter Based on ASTM D543-06 standard practices for evaluating the resistance of plastics to chemical reagents. Tested under 1 % strain Excellent Very good Good Fair Poor Not tested 16 bioplastics MAGAZINE [03/15] Vol. 10

Injection Moulding Chemical resistance “An important step in development of the new formulations,” said Diodato, “was to begin to understand how Ingeo components used for consumer products would perform when exposed to common household chemicals.” The company began a focused series of Environmental Stress Crack Resistance (ESCR) tests comparing Ingeo PLA to ABS. Rather than picking from a standard laundry list of industrial solvents – irrelevant for the non-industrial markets targeted by these grades – NatureWorks used a range of common household chemicals, those typically of interest to brands in its targeted markets. The tests were based on ASTM D543-06 standard practices for evaluating the resistance of plastics to chemical reagents. Test parts were put under 1 % strain. Ingeo medium and high impact formulations and ABS were evaluated at intervals of one hour, 24 hours, and 96 hours. Solvents and chemicals used in the tests included: • Distilled vinegar (five percent acidity) • Isopropanol • AJAX spray and wipe cleaner • Dawn liquid soap • Bertolli extra virgin olive oil • Unsalted butter Both Ingeo and ABS had excellent resistance to distilled vinegar. For Ajax spray, Ingeo was rated excellent at alltime intervals, while ABS was rated as poor after 96 hours. For olive oil and butter, Ingeo achieved an excellent rating at all-time intervals while ABS was rated poor at both 24 and 96 hours. For isopropanol, Ingeo was rated good to very good. For dish soap, Ingeo was rated very good to excellent. ABS was not yet tested for either isopropanol or dish soap. In a further series of independent tests performed by Nypro, a Jabil Company, the chemical resistance of Ingeo and ABS was assessed using a method designed to test how plastics used in consumer electronics stand up to commonly carried items such as hand cream, sunblock, insect repellent, acetone (nail polish), and isopropyl alcohol (hand sanitizer). Ingeo passed each test. ABS failed to pass two tests – insect repellent and nail polish. After the consumer products chemical resistance tests, NatureWorks calculated that if 500,000 mobile phones were molded from Ingeo instead of from ABS the non-renewable energy saved would be equivalent to 750 gallons (2,893 l) of gasoline. The reduction in greenhouse gas emissions would be significant: a savings equivalent to a car driven for 22,000 miles with no emissions. MT Simulating the chemical resistance of plastics used in consumer electronics (Testing performed by Nypro, a Jabil Company) Chemical Ingeo ABS Hand cream Pass Pass Sunblock Pass Pass Insect repellant Pass Fail Acetone (nail polish) Pass Fail Isopropyl alcohol (hand sanitizer) Pass Pass PLA Injection Moulding grades ABS Ingeo injection moulding formulation Medium impact (884-41-1) High impact (884- 41-2) Ingeo profile extrusion formulation High modulus (821- 56-2) Bio content (%) 100 0 89 88 76 Specific gravity (g/m 3 ) 1.24 1.04 1.22 1.21 1.24 Specular gloss 60° 125 89 72 73 77 Specular gloss 20° 112 68 48 47 56 Tensile modulus (Mpa) 3,400 2,316 2,850 2,850 3,125 Tensile yield strength (Mpa) 64 39 37 38 33 Tensile elongation at break (%) 3.6 5.5 32 21 38 Notched Izod impact (J/m) 21 277 139 443 352 Flexural strength (Mpa) 113 68 66 65 59 Flexural modulus (Mpa) 3,640 2,381 3,140 3,100 3,550 Heat distortion (HDT B @ 0,46 MPa) 55 87 92 77 85 bioplastics MAGAZINE [03/15] Vol. 10 17

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