Abstract
Polar amino groups of the waste silk sericin (SS) were modified by isocyanate compounds : 2- (methacryloyloxy)ethyl isocyanate (MOI) or 2-(acryloyloxy)ethyl isocyanate (AOI). By hot-pressing the MOImodified silk sericin (MOISS) or the AOI-modified silk serisin (AOISS), vinyl groups in the MOI or AOI were polymerized and the flexible and transparent films were obtained. Tensile moduli and strengths of the MOISS films were significantly enhanced as the MOI content increased. By the addition of the isocyanate compound, sericin films exhibited the lower solubility to the distilled water (80℃) and also the lower swell ratio to the distilled water (room temperature). For the enhancement of tensile properties and to restrain the water swelling, MOI was more effective than AOI. Biochemical oxygen demand (BOD) / theoretical oxygen demand (TOD) of the pure sericin film was almost 100% after 10days immersion into the activated sludge. By adding the isocyanate compound, BOD/TOD was decreased and delayed. When more than 50mol% of polar amino groups remained unreacted, sericin films retained the biodegradability. From the viewpoint of biodegradability, AOI was more effective than MOI.
