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Effects of chemical versus enzymatic processing of kenaf fibers on poly(hydroxybutyrate-co-valerate)/poly(butylene adipate -co-terephthalate) composite properties

Bing Yang, Mangesh Nar, David K. Visi, Michael Allen, Brian Ayre, Charles L. Webber III, Hongbing Lu, Nandika Anne D'Souza
Composites: Part B 2014 v.56 pp. 926-933
alkali treatment, biocomposites, biopolyesters, crystallization, enzymatic treatment, kenaf, microscopy, polygalacturonase, polyhydroxybutyrate, retting, scanning electron microscopes, soaking, sodium hydroxide, temperature
Fibers from the kenaf plant for composites are extracted using various retting processes. In this paper, we investigate the impact of retting by NaOH alkaline soak and enzymatic retting using pectinase on the crystallization and mechanical performance of a biopolymer blend of poly(hydroxybutyrate-co-valerate)/poly(butylene adipate-co-terephthalate). Two fiber lengths, 5 and 10 mm and a hybrid 1:1 fiber mixture were utilized. From DMA results, the NaOH retted fibers showed synergistic benefits of using hybrid fiber lengths on modulus. The pectinase retted samples did not show synergistic benefits of fiber lengths but composites of the same fiber length retted by pectinase outperformed the corresponding composites with NaOH retted fibers. The fiber retting method also affected recrystallization of the biopolymer. Pectinase retting showed a higher recrystallization temperature than NaOH retting. Transcrystallization resulting from fiber presence was analyzed using polarized optical microscopy. ESEM revealed smoother surfaces on the pectinase retted fibers compared to NaOH.