This research work was to study the improvement of toughness and impact resistance of polylactic acid (PLA) with modified soybean oil (MSBO) and palm fiber (PF). The detail of this work was divided into three parts. The first was to find the suitable condition for modification of soybean oil with ozonolysis. The second and last parts were to study the effects of MSBO and PF contents on the properties of PLA respectively. For oil modification the reaction times were varied from 0 to 3 hours and the chemical changes in molecules of soybean oil were investigated by Nuclear magnetic resonance (NMR) and Fourier transform infrared (FTIR) spectroscopies. The result suggested that the most suitable condition for ozonolysis reaction was 2 hours considering the decrease in double bond between carbon atoms and the increase in hydroxyl group into molecular structure of MSBO. For the effect of MSBO content on mechanical properties it was evaluated by tensile and impact testing. Differential scanning calorimeter (DSC) and scanning electron microscope (SEM) were used for thermal and morphology analyses. The result showed that elongation at break and impact strength of modified PLA by MSBO increased about 89 and 25 % compared to those of neat PLA respectively. MSBO act as the efficient plasticizer for PLA considering the conversion of fracture behavior from brittle to ductile good dispersions of MSBO droplets in PLA and the decrease of glass transition temperature (Tg) with addition of MSBO. The addition of PF improved the impact strength of modified PLA. Strong interfacial bonding between PLA and PF indicated MSBO being both coupling agent for PLA and natural fiber and plasticizer for PLA. For migration test it was found that contents of released heavy metal and migrated chemical from specimens of PLA and PLA/PF composite were under the criteria according to Notification of the Ministry of Public Health (No. 295) B.E. 2548.

Biodegradable polymer blend fibers were prepared by melt spinning technique. Poly(lactic acid) (PLA) and poly(butylene succinate) (PBS) were blended in a twin screw extruder at various contents of PBS at 0-50 wt%. PLA/PBS blends were melt spun using a single screw extruder equipped with multifilaments spinnerette. The effect of PBS contents on morphology thermal properties and mechanical performance of PLA/PBS blend fiber was investigated. SEM micrographs indicated that the addition of PBS at 10 wt% showed miscibility of PLA/PBS blends while the other contents of PBS exhibited phase separation of the blends. The incorporation of PBS affected on the declination of crystallinity in the blends. It can be noted that the addition of PBS could enhance the elasticity of PLA/PBS blend fibers.

The study of vegetable-carved processing packed in hermetically sealed container for 5 types of plant e.g. carrot pumpkin radish green papaya and cucumber which carved into rose or leave shape and preserved in acidified-pickle (7.23% vinegar 64.81% water 0.81% salt 27.00% sugar and 0.15% lactic acid pH 3.27). The processing were conducted by sanitized carved-carrot pumpkin and radish in peroxyacetic acid solution (80 mg/l 3 min) or dipped in tap water (3 min) for green papaya and cucumber. Then all carved-vegetables were blanched in calcium chloride solution (0.5% 3 min) followed by preserved in acidified-pickle in plastic box with a lid and stored for 4 days at room temperature (25ºC). The results showed that pH and °Brix decreased during 4 days storage and showed obviously tended to equilibrium. However carved-radish and cucumber were spoiled by microorganisms as a film on the surface of pickle solution and gas bubble was occurred inside a container on 4th days of the storage. Hence carrot and pumpkin were used in the next experiment which preserved in preservative-added recipe (27.03% vinegar 27.03% water 0.9% salt 45.05% sugar and 200 ppm sodium metabisulfite pH 3.39) with hot-filled method in glass bottle. Treatment was compared with carved-vegetables preserved in acidified-pickle and kept at 4oC as the control. The pH of samples of pickle solution carved-vegetables and mixed-sample of both treatments showed lower than 4.6 and °Brix were gradually decreased during storage periods.The appearance of both treatments were maintain good and not different between treatments. Shelf-life of carved-carrot -pumpkin and -radish stored in hermetically sealed container was up to 7 days. Total bacteria count Escherichia coli yeast-molds were not exceeded than the standard limited by Ministry of Public Health and Staphylococcus aureus was not detected