No abstract

Poly(lactic acid) (PLA) was melt blended with thermoplastic elastomer (TPE) styrene-ethylene-butylene-styrene-g-maleic anhydride (SEBS-g-MA) copolymer using a micro compounder which used melt recirculation approach for efficient dispersion of SEBS-g-MA in PLA. The SEBS-g-MA volume fraction (U d ) was varied between 0.07 and 0.48. Dynamic mechanical analysis showed 10.4 8C decrease in glass transition temperature at U d 5 0.48. Differential scanning calorimetry results exhibited shift in cold crystallization temperature to a higher temperature in the presence of SEBS-g-MA. Thermogravimetric analysis presented enhanced thermal stability of PLA/SEBS-g-MA blends. Tensile strength and modulus decreased while elongation-at-break and Izod impact strength increased in the blends. Theoretical models were employed to analyze the tensile properties of the blends in order to evaluate the blend structure. The microstructural attributes were characterized by wide-angle X-ray diffraction, Fourier-transform infrared spectroscopy, and scanning electron microscopy of cryofractured, impact fractured, and tensile fractured surfaces. V C 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 45644.

In this study, sepiolite nanoclay is used as reinforcing agent for poly(lactic acid) (PLA)/(styreneethylene-butylene-styrene)-g-maleic anhydride copolymer (SEBS-g-MA) 90/10 (w/w) blend.Effects of sepiolite on thermal behavior, morphology, and thermomechanical properties of PLA/SEBS-g-MA blend were investigated. Differential scanning calorimetry results showed 7% improvement in crystallinity at 0.5 wt% of sepiolite. The nanocomposite exhibited approximately 36% increase in the tensile modulus and 17% increase in toughness as compared with the blend matrix at 0.5 and 2.5 wt% of sepiolite respectively. Field emission scanning electron microscopy and transmission electron microscopy images exhibited sepiolite-induced morphological changes and dispersion of sepiolite in both PLA and SEBS-g-MA phases. Dynamic mechanical analysis and wide angle X-ray diffraction present evidences in support of the reinforcing nature of sepiolite and phase interaction between the filler and the matrix. This study confirms that sepiolite can improve tensile modulus and toughness of PLA/SEBS-g-MA blend. Biobased polymers have received a great deal of attention because they minimize the use of petrochemical resources and are superior in eco-friendliness. 1 The poly(lactic acid) (PLA) is a biodegradable polyester with high tensile strength and modulus. However, because of its brittleness, low thermal stability, and tensile toughness, neat PLA is limited in applications. Properly modified PLA can be used in many applications like food packaging, textile, electronics, surgical sutures, drug delivery systems, and transport and building. [2][3][4][5] Techniques such as plasticization, copolymerization, and blending are used to deal with the drawbacks of PLA. Blending is a feasible option compared with other techniques because of its cost effectiveness and minimum trade-off in properties. Blending with a thermoplastic elastomer like SEBS can be an effective way to toughen PLA. The SEBS is widely used in commercial applications such as sealants, footwear, coatings, 6 automotive parts, adhesives, temperature sensors, 7 and wire insulation. Sangeetha et al 8 reported that impact strength was higher in PLA/SEBS-g-MA blends than that in PLA/SEBS, which may be due to the interaction between maleic anhydride groups in SEBS-g-MA and carbonyl groups of PLA. SEBS-g-MA copolymer is used to toughen many polymers such as polypropylene (PP), 9 high density polyethylene, 10 nylon-6, 11 nylon-6,6 12 and PLA. 8,[13][14][15] reported that SEBS-g-MA is an effective impact modifier for PP/PLA blends. However, tensile modulus and strength decreased.Various kinds of fillers such as organo-modified montmorillonite (OMMT), [16][17][18][19] carbon nanotubes (CNTs), 20-22 calcium carbonate, [23][24][25] silica, 26-28 and carbon fullerenes 29,30 are used to enhance the thermomechanical properties of PLA. Although, OMMTs and carbon nanotubes worked well with PLA, the formers need special organic treatments to get exfoliated, while the latters are expensive and are detrimen...