Poly(lactic acid) (PLA)/poly(butylene adipate-co-terephthalate) (PBAT) blends were compatibilized using epoxidized polyhedral oligomeric silsesquioxanes (Epoxy-POSS). Three different Epoxy-POSS types were utilized having mono-, tri-, and multi-epoxides per POSS cage. In order to understand the localization of Epoxy-POSS types, wetting coefficients were calculated from surface energy measurements. According to scanning electron microscopy (SEM) and transmission electron microscopy (TEM), it was observed that Epoxy-POSS types mostly located at the interface of PLA/PBAT phases. The compatibilization of PLA and PBAT was shown through the decrease in dispersed particles size and the shifts in glass transition temperatures of phases. Mechanical properties of PLA/PBAT improved in the presence of Epoxy-POSS types. The Izod impact strength and elongation in tensile test values were maximized when 0.5% monoepoxy-POSS was used as compatibilizer. The reactions between Epoxy-POSS and polymers were monitored by Fourier transform infrared (FTIR) analysis and rheology.PBAT. 7 PBAT is an aliphatic-aromatic copolymer, which resembles to LDPE in term of its features. It has a great toughness, flexibility, low glass transition temperature, and it is fully biodegradable. PBAT has been considered as a good nominee for the toughening the PLA owing to its high flexibility. 8 However, PLA/PBAT blends show multiphase behavior due to incompatible characters of each component, which results in poor mechanical properties. PLA/PBAT blends can be compatibilized in order to strengthen the interfacial adhesion and to reduce the interfacial tension between phases. 9 Moreover, compatibilization can also improve the morphological stability of the blend.Al-Itry and coworkers used a commercial epoxidized styreneacrylic copolymer as a compatibilizer in PLA/PBAT blends. They found that the compatibilizer enhanced the tensile toughness of PLA/PBAT blends. It was seen from scanning electron microscopy (SEM) and transmission electron microscopy (TEM) pictures that the interfacial adhesion was improved in the presence of compatibilizer. 8 Kumar et al. focused on glycidyl methacrylate (GMA) compatibilizer on the thermal, mechanical, thermomechanical, and morphological properties of PLA/PBAT blends. It was reported that impact strength of PLA/PBAT blends increased in the presence of GMA. The glass transition temperatures of PLA and PBAT phases shifted to each other that proved the enhanced compatibilization. Moreover, the morphological results figured-out that the interfacial adhesion was successfully achieved Additional Supporting Information may be found in the online version of this article.

This article focuses on the effect of molecular weight of poly(butylene adipate-co-terephthalate) (PBAT) on the immiscible poly(lactic acid) (PLA)/PBAT blends compatibilized with epoxidized polyhedral oligomeric silsesquioxanes (Epoxy-POSSs) having different numbers of epoxy groups per molecule. Mechanical, thermomechanical, thermal, rheological, and morphological properties of the blends were investigated as a function of PBAT molecular weight and epoxy-POSS type. Mechanical tests revealed that all epoxy-POSS types significantly improved the performance of the blends containing low-molecular-weight PBAT. On the other hand, epoxy-POSS with three epoxy functional groups (TriEpPOSS) and Epoxy-POSS with multiple-epoxy functional groups (MuEpPOSS) only slightly improved the performance of blends with highmolecular-weight PBAT. Thermomechanical and thermal test results supported that the compatibilization effects of the epoxy-POSSs were more prominent in the PLA/PBAT blends with low-molecular-weight PBAT due to the observation of the shifts in the glass transition temperatures of the PLA phase. According to the rheological results, the addition of epoxy-POSSs increased the interactions between the PLA and PBAT phases much more effectively in the PLA/PBAT with low-molecular-weight PBAT. The dispersed phase size of the PBAT further decreased in the low-molecular-weight PLA/PBAT blend system due to the enhanced compatibility much better. POLYM. ENG. SCI., 60:398-413, 2020.

In this study, the compatibilization effects of triglycidylisobutyl polyhedral oligomeric silsesquioxane (TEpPOSS) on biodegradable poly(lactic acid) (PLA)/thermoplastic polyurethane (TPU) blends were investigated. All blends were prepared via melt blending and PLA/TPU (80/20, 70/30, 50/50 wt%) ratio was selected as the experimental parameter. In order to predict the selective localization of TEpPOSS thermodynamically, wetting coefficient were determined by means of surface energy measurements. Morphological analyses were carried out by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Moreover, rheological, mechanical, thermomechanical and thermal properties of the blends were performed via rheometer, universal tensile tester, dynamic mechanic analyses and differential scanning calorimeter (DSC), respectively. Morphological test results revealed that TEpPOSSs were mostly located at the interfaces of the PLA and TPU phases. According to the rheological studies, the interfacial interactions between PLA and TPU were improved with the addition of TEpPOSS, which resulted from the potential reactions between epoxy-carboxylic acid and/or epoxy-hydroxyl functional groups. The addition of TEpPOSS enhanced the mechanical properties of PLA/TPU blends. DSC test results revealed a decrease in the glass transition temperatures of PLA in the presence of TEpPOSS, which was an another indication of improved compatibility between PLA and TPU.

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Effects of Epoxy-POSSAbstract: In this study, the influence of epoxy functionalized polyhedral oligomeric silsesquioxanes (G-POSS) loading level on the mechanical, thermal and rheological properties of poly(lactic acid) (PLA)/thermoplastic polyurethane (TPU) blends were investigated. The blends were prepared in an Xplore Instruments MC15 twin-screw microcompounder at 200 C barrel temperature and 100 rpm screw speed. Mechanical properties were characterized by tensile and impact tests, thermal properties were determined via differential scanning calorimeter (DSC) and thermogravimetric analysis (TGA). Rheological properties were examined by oscillatory rheometer. A decreasing trend in tensile strength and thermal degradation temperature were obtained for PLA/TPU blends at high G-POSS loading levels. G-POSS loading level did not exhibit significant effect on glass transition, crystallization and melting temperatures of the blends.