title: Overcoming the Fundamental Challenges in Improving the Impact Strength and Crystallinity of PLA Biocomposites: Influence of Nucleating Agent and Mold Temperature.
abstract: Poly(lactic acid) (PLA), one of the widely studied renewable resource based biopolymers, has yet to gain a strong commercial standpoint because of certain property limitations. This work is a successful attempt in achieving PLA biocomposites that showed concurrent improvements in impact strength and heat deflection temperature (HDT). Biocomposites were fabricated from a super toughened ternary blend of PLA, poly(ether-b-amide) elastomeric copolymer and ethylene-methyl acrylate-glycidyl methacrylate and miscanthus fibers. The effects of varying the processing parameters and addition of various nucleating agents were investigated. Crystallinity was controlled by optimizing the mold temperature and cycle time of the injection process. With the addition of 1 wt % aromatic sulfonate derivative (Lak-301) as a nucleating agent at a mold temperature of 110 °C, PLA biocomposites exhibited dramatic reduction in crystallization half time to 1.3 min with crystallinity content of 42%. Mechanical and thermal properties assessment for these biocomposites revealed a 4-fold increase in impact strength compared to neat PLA. The HDT of PLA biocomposites increased to 85 °C from 55 °C compared to neat PLA. Crystallization behavior was studied in detail using differential scanning calorimetry and was supported with observations from wide-angle X-ray diffraction profiles and polarized optical microscopy. The presence of a nucleating agent did not alter the crystal structure of PLA; however, a significant difference in spherulite size, crystallization rate and content was observed. Fracture surface morphology and distribution of nucleating agent in the PLA biocomposites were investigated through scanning electron microscopy.
authors.affiliation: †School of Engineering, University of Guelph, Thornborough Building, Guelph, N1G2W1 Ontario, Canada.|‡Bioproducts Discovery and Development Centre, Department of Plant Agriculture, University of Guelph, Crop Science Building, Guelph, N1G2W1 Ontario, Canada.
authors.forename: Vidhya
authors.initials: V
authors.lastname: Nagarajan
authors.affiliation: †School of Engineering, University of Guelph, Thornborough Building, Guelph, N1G2W1 Ontario, Canada.|‡Bioproducts Discovery and Development Centre, Department of Plant Agriculture, University of Guelph, Crop Science Building, Guelph, N1G2W1 Ontario, Canada.
authors.forename: Kunyu
authors.initials: K
authors.lastname: Zhang
authors.affiliation: †School of Engineering, University of Guelph, Thornborough Building, Guelph, N1G2W1 Ontario, Canada.|‡Bioproducts Discovery and Development Centre, Department of Plant Agriculture, University of Guelph, Crop Science Building, Guelph, N1G2W1 Ontario, Canada.
authors.forename: Manjusri
authors.initials: M
authors.lastname: Misra
authors.affiliation: †School of Engineering, University of Guelph, Thornborough Building, Guelph, N1G2W1 Ontario, Canada.|‡Bioproducts Discovery and Development Centre, Department of Plant Agriculture, University of Guelph, Crop Science Building, Guelph, N1G2W1 Ontario, Canada.
authors.forename: Amar K
authors.initials: AK
authors.lastname: Mohanty
mesh_terms: D019245:Compressive Strength; D003460:Crystallization / Q000379:methods*; D006244:Hardness; D019344:Lactic Acid / Q000737:chemistry*; D008422:Materials Testing; D010936:Plant Extracts / Q000737:chemistry*; D006109:Poaceae / Q000737:chemistry*; D011091:Polyesters; D011108:Polymers / Q000737:chemistry*; D013696:Temperature
chemical_list: D010936:Plant Extracts; D011091:Polyesters; D011108:Polymers; D019344:Lactic Acid; C033616:poly(lactide)
keywords: crystallization; heat deflection temperature; impact strength; injection molding; mold temperature; nucleating agent; poly(lactic acid)