This study demonstrates a practical means to overcome inherent brittleness problem of poly(lactic acid) (PLA) and make PLA feasible as packaging material. PLA with suitable processability is utterly required for package manufacturers, where flexible, tough PLA film is essential for packers and end users. Highly flexible PLA films with 60-fold increase in elongation at break (Eb) over that of the neat PLA were successfully produced by integrating effective reactive blending and economical film blowing process. The 'two-step' blending was used to prepare PLA compound; poly(butylene adipate-co-terephthalate) (PBAT -another biodegradable polymer) was first blended with 0.5-1% chain extender (epoxy-functionalized styrene acrylic copolymer) (ESA), followed by subsequent blending with PLA in twin-screw extruder. Blown films of reactive blend of PLA/PBAT/ESA (80/20/1) showed impressively high Eb of 250% versus a very low Eb of 4% for the neat PLA. Resulting blown films still possessed high modulus of 2 GPa, yield stress of 50-60 MPa and good toughness of~100 MPa. Significant enhancement in the film's ductility was attributed to homogeneous blend with developed fine strand-like structure as a result of effective in situ compatibilization and good interfacial adhesion between the PLA and PBAT. PLA/PBAT/ESA blend also offered improved processability. Resulting films had acceptable haze of~10% for common packaging, and clearer film close to PLA (≤2%) could be obtained by designing PLA skin layers in multilayer structure. Films of PLA/PBAT/1%ESA exhibit potential as packaging material; their mechanical and optical properties are comparable with or even exceed some existing films used in the market.

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The symmetrical A/B/A structure of multilayer blown films was fabricated in this study. The immiscible low-density polyethylene/polylactic acid (LDPE/PLA) blend was set as a core (B) layer and LDPE was used as skin (A) layers. The compositions of PLA in the core layer were varied from 20 to 50 wt%. The thickness of each layer was 10 μm (total film thickness of~30 μm). In a blown film co-extrusion process, the morphology of the fiber/ribbon-like structures of LDPE/PLA blend was developed.Such structures had interesting effects on gas permeability and aroma barrier properties of the films. For instance, multilayer LDPE films containing 40 and 50 wt% PLA (P40 and P50) showed the reduction of oxygen permeability (PO 2 ) approximately 20% and 43%, respectively, compared with the neat LDPE film. A long tortuous path for gas and aroma transportation through film thickness was created from the developed ribbon-like structures of the PLA minor phase. For durian packaging application, fresh-cut durian of 300 g was packed in the developed multilayer films, LDPE, and HDPE (Control), stored at 4°C for 7 days. Results demonstrated that the steadystate condition of 10% to 13% O 2 and 8% to 10% CO 2 was achieved in all packages except in the HDPE. Moreover, the P40 and P50 films exhibited an outstanding aroma barrier property for three major durian volatiles: diethyl sulfide, ethyl propanoate, and 2-ethyl-1-hexanol. Overall results clearly indicated that the multilayer LDPE films containing PLA exhibited a significantly improved aroma barrier performance with optimum gas permeability desirable for modified atmosphere packaging to retain quality of fresh-cut durian throughout the storage period. KEYWORDS aroma barrier packaging, low-density polyethylene, modified atmosphere packaging, multilayer film, polylactic acid

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In this work, PCC was prepared from chicken eggshell powder (ESP) by dissolving 100 g ESP in 1 M hydrochloric acid at room temperature. Under vigorous stirring, PCC was precipitated from the ESP-dissolved solution using 1 M sodium carbonate solution. The dried PESP (precipitated eggshell powder) was then characterized by particle size analyzer, X-ray diffractometer, Brunauer-Emmett-Teller surface analyzer and thermogravimetric analyzer. The particle shape of the PESP was revealed using scanning electron microscope. It was found that PESP was a binary mixer of calcite and vaterite. The particles were in cubic and spherical shape. In addition, PESP had a volume average diameter of 8.16 μm, D[V, 0.5] of 7.22 μm, D[V,0.9] of 16.57 μm, and the specific surface area of 4.38 m2/g. The average particle size was lower than and the specific surface area was higher than that of ESP. The decomposition process of PESP occured in a single step between 610 and 770 °C, with 44.43% weight loss.