Raj Krishnaswamy, Allen Padwa* Metabolix, Inc. *Speaker

Transcription

1 Impact Modification of PLA Using Biobased, Biodegradable Mirel TM PHB Copolymers Raj Krishnaswamy, Allen Padwa* Metabolix, Inc. *Speaker

2 OUTLINE Background on PLA, PHB Copolymers PLA Impact Modification Approaches Results on PLA/PHB Copolymer Blends Summary 2

3 Poly(lactic acid) Biobased and compostable aliphatic polyester NatureWorks, LLC has demonstrated success in a variety of sheet, fiber and blend applications Low impact toughness and low end-use temperature are important considerations for even larger-scale commercial adoption of PLA 3

4 PLA Toughening Approaches (1 of 8) Plasticizers Mineral Fillers Traditional Impact Modifiers Other Compostable Polymers 4

5 PLA Toughening Approaches (2 of 8) Plasticizers Citrate esters & low-mw PEG have shown only modest improvements in toughness Tensile strength is lowered Tg is reduced (depending on miscibility). Lowering Tg accelerates physical aging at room temperature, which results in shelf-life concerns. 5

6 PLA Toughening Approaches (3 of 8) Mineral Fillers Precipitated CaCO 3 (EM Force Bio), at 30% 2.5 loading, provides substantial improvement in the impact toughness of PLA. Izod Impact (ft.lb/inch.) % EM Force Bio CaCO3 Pure PLA 0.0 Pure PLA PLA/CaCO3 70/30 6

7 PLA Toughening Approaches (4 of 8) Traditional Impact Modifiers Ethylene acrylate copolymers [Biomax Strong 120] TPU modifiers [Estane 2102] ABS modifiers [Blendex 3160; 60% rubber] 7

8 PLA Toughening Approaches (5 of 8) Traditional Impact 10% Loading; Compounded by twin-screw extrusion Izod Impact (ft.lb/inch.) Pure PLA Biomax Strong 120 Estane 2102 Blendex

9 PLA Toughening Approaches (6 of 8) Traditional Impact Modifiers ABS impact modifiers [Blendex 3160; 60% rubber] provide significant impact toughening of PLA. However, adding any of these impact modifiers will compromise the compostability of the PLA. Biobased carbon content is also lowered. 9

10 PLA Toughening Approaches (7 of 8) Other Compostable Polymers PCL has shown modest promise. PBS, PBSA, and PBAT are also promising. Amongst all compostable polymers, PBSA has shown the best impact modification of PLA. US Patent 5,883,199 [McCarthy, et. al.] will serve as a benchmark in our effort 10

11 PLA Toughening Approaches (8 of 8) Tensile Elongation (%) PLA/PBSA Blends US Patent 5,883, Wt% PBSA Tensile Toughness (MJ/m 3 ) PLA/PBSA Blends US Patent 5,883, Wt% PBSA 11

12 Objective Impact Modification of PLA Using PHB Copolymers Without compromising biobased carbon content AND compostability of PLA Will explore semi-crystalline PHB copolymer (sc-phb) amorphous, low Tg PHB copolymer (a-phb) 12

13 Mirel TM PHB Copolymers Biodegradable Soil (Ambient) Home Compost Industrial Compost Fresh Water Marine Water Anaerobic Biobased Sugar used as feedstock Products Can be fabricated using conventional plastics processing equipment. Fermentation Microbial engineering enables high polymer accumulation in microbes as well as control of polymer structure 13

14 sc-phb Copolymers Poly(3-hydroxy butyrate) homopolymer Highly crystalline (~ 65%), high Tm (~ 160C) With copolymers, control of Tg, Tm and crystallinity is possible. 14

15 DSC of sc-phb Copolymer Low Tg phase About 20% crystalline 15

16 PLA/sc-PHB Blends Elongation to Break (%) Regular Blends Compatibilized Blends Wt% % M4100 sc-phb 16

17 PLA/sc-PHB Blends Tensile Toughness (J) 2.0 Regular Blends Compatibilized Blends PBSA Blend (USP 5,883,199) Wt% % sc-phb M4100 improvement over benchmark 17

18 Blends with other Compostable Polymers % loading of second polymer into PLA Izod Impact (ft.lb/inch.) sc-phb impact modification is similar to that of PBS & PBAT. 0.2 Pure PLA PBAT PBS M

19 DSC of a-phb a-phb is an amorphous, low-tg rubber. Cool at 10C/min Heat at 40C/min 19

20 PLA/a-PHB Blends Izod Impact (ft.lb./inch) Standard Blends Compatibilized Blends Significantly improved over sc-phb Compatibilized blends much better Wt% % M4300 sc-phb 20

21 PLA/a-PHB Blends Tensile Strength (MPa) 75 Standard Blends Compatibilized Blends Tensile strength is higher for compatibilized blends. Trend similar to other compostable polymers such as PBS & PBAT Wt Wt% % sc-phb M

22 PLA/a-PHB Blends Tensile Modulus (MPa) Tensile modulus is not as greatly influenced by compatibilization. Trend similar to other compostable polymers such as PBS & PBAT Wt% % M4300 sc-phb 22

23 PLA/a-PHB Blends Two-Phase Structure Evident in Blends Component Tg largely unchanged T g ( C) PLA Tg: Standard Blends PLA Tg: Compatibilized Blends M4300 a-phb Tg: Standard Blends M4300 a-phb Tg: Compatibilized Blends Wt Wt% % sc-phb M

24 PLA/a-PHB Blends Heat Flow [Endo >] DSC Heating 40 C/min Post Cooling From the 10 C/min M4300: a-phb: T g ~ -35 C PLA: T g ~ 50 C Multi-Phase Morphology Two Distinct Phases Temperature ( C) 24

25 Impact Benchmarking 10 All Polymeric Impact Modifiers Izod Impact (ft.lb/inch.) Pure PLA Biomax Strong 120 Estane 2102 Blendex 3160 PBAT PBS M4100 M4300 M4300 Comp-Blend 25

26 Impact Benchmarking ONLY Compostable Impact Modifiers 6 5 Izod Impact (ft.lb/inch.) a-phb = Clear Winner 0 Pure PLA PBAT PBS M4100 M4300 M4300 Comp-Blend 26

27 Competitive Benchmarking Modulus Izod Impact Yield Strength PLA PLA/PHA /a-phb Impact PP PBT PC Elongation Break Strength 27

28 Summary PLA blends with a-phb copolymer results in significant improvement in impact toughness with a modest decrease in modulus and strength. Izod impact 0.4 -> % a-phb NO compromise to biobased content and compostability of PLA Modulus-Strength-Toughness Balance rivals that of polymers used in engineering applications! 28