EFFECT OF DIFFERENT RELATIVE HUMIDITY ON MECHANICAL PROPERTIES OF STARCH-BASED BIODEGRADABLE PLASTICS FILLED WITH CELLULOSE ACETATE

摘要

Cellulose acetate as an additive blended with acetylated starch to extrude a plastic sheet was successfully earned out When cellulose acetate was added, tensile strength and water resistant of the extruded plastic sheets was effectively improved, however, elongation reduced. When more than 15% cellulose acetate was added, the extrusion becomes difficult due to high viscosity. Therefore, the added cellulose acetate content was limited to 15%. The extruded plastic sheets stored at high relative humidity (RH) (51.93%) had the lower strength, while it had higher elongation and water solubility index. On the contrary, in the case of the low humidity (33.51%), the tensile strength increased and elongation reduced. As the relative humidity increased from 33 to 93%, the moisture content of extruded plastic sheets increased due to absorbed moisture from air, indicating that water interacts with the acetylated starch and cellulose acetate to increase free volume, therefore, glass transition temperature (Tg)of the extruded plastic sheets became low.