The authors disclosed the biaxially stretched film that exhibited uniaxial heat shrinkage properties as well as high tensile strength both in the machine direction (MD), and the traverse direction (TD). The heat shrinkable co-polyester (Co-PES) film was produced using a sequential biaxial stretching process, which was conducted in the order of stretching in TD, the first annealing (TS 1), stretching in MD and the second annealing (TS 2). The first annealing temperature was important to control the properties. However, the film structure change caused by the first annealing is unclear.
The objective of this study was to investigate the relationship between the properties and structural characteristics of the film. The raw material of experiments were used so that the Co-PES was random co-polymer of ethylene terephthalate and neopentyl glycol as well as previous paper, and the homogeneous poly(ethylene terephthalate) (PET) for comparison. The biaxially stretched Co-PES films were prepared by changing the temperature and the relaxation ratio at TS 1. The PET films were also prepared under similar processing conditions while changing the temperature at TS 1 process.
TD shrinkage at 90°C of all films decreased when increasing of the first annealing temperature or the TD relaxation ratio. However, TD tensile strength is poorly correlated with the conditions. Though the phenomenon could not be explained by polymer crystallization and molecular orientation, the trans-conformation index of those films was well correlated with both shrinkage and tensile strength. The trans-conformation remained in stable structure and high molecular orientation. Therefore, even though shrinkage was decreased, the Co-PES films showed high tensile strength because of high amount of trans-conformation in TD. The consideration is that stable and/or rigid oriented amorphous represented the trade-off of shrinkage and tensile strength.
On the other hand, all films in MD showed high shrinkage and high strength as ordinary shrinkable films because there was no application of high annealing temperature after the MD stretching.

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Poly(lactic acid) (PLA) has attracted much attention recently as green plastic, but its use is still limited because of its low crystallinity and productivity. A modified PLA compound for injection molding was developed by adding nucleating agents and a plasticizer into PLA. Furthermore, addition of filler compounds into PLA was examined to increase the strength and the modulus of PLA. In this study, modified PLA composites containing amorphous cellulose and crystalline cellulose fillers were investigated. The amorphous cellulose filler was made by a mechanochemical reaction. Compared to the modified PLA without cellulose, the PLA/crystalline cellulose composite had increased stiffness and heat resistance, but greatly decreased fracture toughness. The decrease of fracture toughness of the PLA/amorphous cellulose composite was much smaller than that of the PLA/crystalline cellulose composite. To explain these results, scanning electron microscopy and atomic force microscopy were performed. The microscopy observations indicated that the interface of PLA and amorphous cellulose was more cohesive and this prevented the occurrence of microcracks. Effect of further pulverization of amorphous cellulose was also investigated. By using microamorphous cellulose, the impact strength of PLA/amorphous cellulose composite improved by 46 percent.

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