The Study on Moulding Technology of Starch-Based Totally-Biodegradable Plastic Products

摘要

Based on monofactorial comparison experiment, the following two excellent technological formations was derived for the production of starch-based totallybiodegradable tray via extruding, pelleting, slicing, and sucking molding: The first formulation: 40% of starch, 12.5% of DOP, 5% of EVA, 15% of polyvinyl alcohol, 20% of talc power and calcium carbonate, and 7.5% of other materials. The material temperature in high-speed kneader was about 9°C, rotation velocity was 600 r/min, kneading duration was 5～10 minutes, diameter of screw stem of extruder was 90 mm, ratio of length versus diameter of screw stem (L/D) was 44, rotation velocity of the screws stem was 40～50 r/min. Temperature in four segments of extruder were 145°C, 155 °C, 150°C, and 160°C respectively, and temperature in extruder head was 170°C;the material rod extruded was set while passing a cold water bath, and then was cut to pellets whose size was 3 mm×3 mm;the latter was transformed into slices and subject to sucking molding after predrying;temperature of sucking molding was 180～190°C, and sucking molding duration was 15～20 seconds. The second formulation: 60% of starch, 15% of DOP, 5% of PHB, 15% of polyvinyl alcohol, and 5% of other materials. All technological parameters were the same with that for the first formulation. According to the test result of Chinese institute of plastic processing, the biodegradation ratio of the tray made through the above treatment 1 and 2 in 30 days amounted to 54.2% and 70.6% respectively, which showed that a satisfied biodegradation effect was realized.