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In this work, we report a melt blend of poly(lactic acid)(PLA)/epoxidized natural rubber (ENR) with liquid natural rubber (LNR). The LNR was synthesized by a photochemical degradation technique and used as a compatibilizer in the PLA/rubber binary blending systems. The PLA/ENR/LNR blends were melt-blended in a Haake internal mixer at 180°C and mixing speed of 50 r. min−1 for 15 min. It was found that the addition of LNR compatibilizer has improved the tensile strength and elongation at break for the compositions of the 40PLA/55ENR/5LNR blend system when compared with a noncompatibilized system (40PLA/55ENR/5NR). The elongation at break for the blend with 5% LNR compatibilizer showed a twofold increment compared with the blend without LNR. The increase in tensile strength and elongation at break were associated with the ability of LNR to promote the uniform dispersion between the natural rubber (NR) and PLA phases as observed in the scanning electron microscopic analysis. Moreover, the differential scanning calorimetric results indicated that the 40PLA/55ENR/5LNR showed the highest degree of crystallinity and thus contributed to improve their mechanical properties. Thermogravimetric analysis showed that two degradation transitions for both compatibilized and noncompatibilized blend systems due to higher degradation temperatures of ENR50 and NR parts. Fourier transform infrared spectroscopic analysis revealed that the PLA/ENR/NR and PLA/ENR/LNR blends were not miscible.

In this study, sago starch was physically blended with low-density polyethylene (LDPE) via the melt blending process followed by injection molding to produce LDPE/sago starch (LPS) composites. The sago starch content was varied from 5 to 30 wt% of LDPE. The addition of starch to LDPE reduced the melt flow rate (MFR), the tensile strength, and impact strength, whereas the tensile modulus, flexural strength, and flexural modulus increased. To improve poor mechanical properties of the LPS, LDPE/glycerol thermoplastic starch (LPGTS) or LDPE/2:1 mixture of glycerol and urea thermoplastic starch (LPMTS) was used in this study. The effect of compatibilizer (maleic anhydride) on properties of the LPMTS specimens was also investigated. The LPS, LPGTS, LPMTS, and maleic anhydride treated LPMTS (LPMTSM) samples were analyzed for the MFR, mechanical properties (tensile, flexural, and impact tests), thermal (TGA and DSC), and morphological properties. As a result, the incorporation of plasticizers or compatibilizer into LPS caused the considerable improvement in MFR and mechanical properties. Moreover, the presence of compatibilizer produced better properties for the LPMTSM sample than for the other samples, indicating better dispersion and homogeneity of starch to the matrix. In addition, thermal stability, DSC, and phase morphology were carried out for different LPS samples. C 2015 Wiley Periodicals, Inc. Adv Polym Technol 2016; View this article online at wileyonlinelibrary.com.

This paper reports a melt blend of poly(lactic acid)/liquid natural rubber with Cloisite C30B (C30B). The mechanical, thermal and morphological properties of poly(lactic acid)/liquid natural rubber and nanocomposites were investigated. Results indicate that Young’s modulus and flexural modulus increased with the addition of C30B to the poly(lactic acid)/liquid natural rubber blend. The elongation at break of poly(lactic acid)/liquid natural rubber increased significantly as compared to nanocomposite with 1% of C30B, i.e. from 37.3% to 62.4%. Nevertheless, the elongation at break and impact strength decreased gradually when nanoclay content increased above 3%, suggesting the addition of clay changed the strain response in the blend systems. The incorporation of nanoclay in the poly(lactic acid)/liquid natural rubber blends lowered the glass transition temperature values relative to poly(lactic acid). This behavior may be associated with more free volume available in the nanocomposite blend systems compared with pure poly(lactic acid). Morphological analyses by scanning electron microscope and transmission electron microscope revealed that different types of morphologies exist for poly(lactic acid)/liquid natural rubber and nanocomposites. This study indicates that poly(lactic acid)/liquid natural rubber-toughened nanocomposites with a higher modulus and that thermal stability could be produced.