Super Toughened Poly(lactic acid) Ternary Blends by Simultaneous Dynamic Vulcanization and Interfacial Compatibilization

Abstract

In this study, a poly(lactic acid) (PLA) ternary blend system consisting of PLA, an epoxycontaining elastomer, and a zinc ionomer was introduced and studied in detail. Transmission electron microscopy revealed that the "salami"-like phase structure was formed in the ternary blends. While increase in blending temperature had little effects on the tensile properties of the resulting blends, it greatly changed the impact strength. For the blends prepared at 240 °C by extrusion blending, the resulting PLA ternary blends displayed supertoughness with moderate levels of strength and modulus. It was found that the zinc ions catalyzed the cross-linking of epoxy-containing elastomer and also promoted the reactive compatibilization at the interface of PLA and the elastomer. Both blending temperature and elastomer/ionomer ratio were found to play important roles in achieving supertoughness of the blends. The significant increase in notched impact strength was attributed to the effective interfacial compatibilization at elevated blending temperatures.

Polylactide/Biopolyethylene bioblends

“…PLA/PE binary blend presents a melt index value between the values of PLA and PE neat polymers, whereas, the ternary blends present a significant decrease in the melt fluidity (from 3.0 to 1.4 for the PLA/PE/E-GMA blend and from 3.0 to 0.5 for PLA/PE/E-GMA blend). These results indicate the formation of PLA-E-GMA and PLA-EMA-GMA copolymers during the extrusion process, probably due the formation of bonds between the epoxy groups present in GMA and the carboxyl and hydroxyl functional end-groups present in PLA, as suggested by the authors in previous work [17] , based on FTIR characterizations, and also by other authors [2,4,20] . …”

“…However, PLA inherent brittleness is a major drawback that prevents its use in a wide range of applications. To overcome this problem, melt blending PLA with other polymers has proved to be the most economic and practical route [1][2][3][4] . Since 2010, Braskem, a Brazilian petrochemical company, has been commercializing the green polyethylene (Biopolyethylene).…”

Selective localization of titanium dioxide nanoparticles at the interface and its effect on the impact toughness of poly(L-lactide)/poly(ether)urethane blends

“…For each measurement, about 5 mg of the sample was directly heated from 0 to 200°C at a heating rate of 10°C/min. The value of were determined using the most commonly used Equation (3) [21,22,41]: (3) where "H m and "H c are the enthalpies of melting and cold crystallization, respectively; w f is the weight percent of the PLLA matrix, and "H m 0 is the melting enthalpy of completely crystalline PLLA (93.7 J/g [42]). …”

Fully bio-based, highly toughened and heat-resistant poly(L-lactide) ternary blends via dynamic vulcanization with poly(D-lactide) and unsaturated bioelastomer

“…Dynamic vulcanization, involving selective crosslinking of rubber polymer during melt blending with a thermoplastic polymer, has been demonstrated to be a powerful technique to control the morphology, enhance interfacial adhesion, and improve the final properties of PLLA blends with elastic polymers [19][20][21][22][23]. Some supertough PLLA blends with impact strengths of more than 530 J m −1 (or 53 kJ m −2 ) have been achieved by dynamic vulcanization of PLLA with some elastic polymers [22,[24][25][26][27][28]. It is worth noting that the sustainability of PLLA was compromised since most elastic polymers in previous studies were prepared from non-renewable feedstocks [19,25,28,29].…”

“…Some supertough PLLA blends with impact strengths of more than 530 J m −1 (or 53 kJ m −2 ) have been achieved by dynamic vulcanization of PLLA with some elastic polymers [22,[24][25][26][27][28]. It is worth noting that the sustainability of PLLA was compromised since most elastic polymers in previous studies were prepared from non-renewable feedstocks [19,25,28,29]. In this sense, some sustainable elastomers such as natural rubber, epoxidized natural rubber, and bioelastomer have gained much attention in fabricating fully sustainable supertough PLLA via dynamic vulcanization [22,24,30,31].…”