The Research Of PVAc/starch Blending Membranes

With the increasing use of one-off plastic product, the pollution results from the plastic waste has become more and more serious. So the development of totally-biodegradable plastics has become the main task of many scientists.In this paper, vinyl acetate and acrylic acid were synthesized through emulsion polymerization under the temperature of 80°C, polyvinyl acetate was modified by acrylic with 0%, 2%, 4%, 6%, 8%, 10%(weight/weight) content, the emulsifier and initiator each occupied with 2.5% and 0.7% of monomer Afterwards, the polyester was blended with starch (0%, 20%, 40%, 60%, 80%) to obtain the biodegradable plastic. Their mechanical properties, rheological properties, thermal stability and morphology were evaluated by mechanical performance testing instruments, capillary rheometry, thermogravimetry and scanning electronic micrograph. The effects of AA and starch amounts on the properties above were studied. The main results are summarized as follows.1. The SEM micrographs shows that with the increasing amount of acrylic acid the compatibility of polyester and starch blends is greatly improved, owing to the formation of an ester carbonyl group, led to a better dispersion and homogeneity of starch in the polyester matrix.2. Mechanical properties of polyester became worse when it was blended with starch, starch is the reinforce agent of polyester and polyester can be used as plasticizer in the blends, the blends with 10% acrylic acid gave the highest tensile strength of about 6.6MPa with about 125% elongation.3. Using capillary rheometer to obtain the rheological properties: the blends melt is non-Newtonian fluid, the relationship between na (apparent viscosity) and τ_w (shear stress) is linear; with the AA content increasing, the non-Newtonian index tend to decrease(less than one) but apparent viscosity tend to increase.4. Thermal properties were examined using differential scanning calorimetry (DSC) and Thermogravimetry (TG). The stability of the blends became worse with the increased starch but better with the increased acrylic acid.5. The biodegradation ratio of the film can exceed 60% in the soil after 15 days.