Evaluation of Novel Back-flush Filtration for Removal of Homopolymer from Starch-g-PMMA

摘要

Starch-g-poly(methyl methacrylate) (PMMA) was prepared by emulsion photopolymerization without photoinitiator. Grafting efficiency was determined for two types of starch (high-amylose and amylopectin) and at several illumination times. Since clogging of the graft copolymer prevented vacuum filtration and Soxhlet extraction was too time-consuming, a new method to separate the PMMA homopolymer from the graft copolymer was developed. Back-flush filtration uses an intermittent pressure pulse to clean the filter as the homopolymer is separated from the graft copolymer. Back-flush filtration was shown to be more efficient by reducing the separation time and solvent use, and the grafting efficiencies obtained with back-flush filtration compare favorably with those from Soxhlet extraction for the starch-g-PMMA copolymer systems studied. More accurate grafting efficiencies could be obtained by applying a nonstick coating to the inside chamber of the back-flush filtration unit.