SynopsisThe gelation of mixed solutions of silk fibroin (SF) /syndiotactic-rich poly (vinyl alcohol) ( s -PVA), the thermal analysis of dry-gels, and the various properties of blend films were investigated. The rate of gelation of a mixed solution was lower than that of each SF or s-PVA solution of the same concentration. In the DSC thermograph of mixed dry-gel (SF/s-PVA = 2 / 8 ~ 8 / 2 ) 2 endothermic peaks corresponding to SF (at 288-299°C: decomposition) and s-PVA (at 233-241°C: melting) were found. Namely, microphase segregation took place. This was confirmed by optical and electron microscopes. The mechanical properties of blend films did not have additive properties. The degree of swelling in water of blend films was independent on water temperature or methanol treatment. The mechanochemical behaviors were barely observed by the pH exchange between p H 2 and 12 only under lower loads. The addition of SF into s-PVA films promoted the permeation of neutral salts.
SynopsisThe preparation of PVA films and fibers with high modulus and high strength was examined. The high drawing was attained when both the drawing just before melting and the relaxation a t room temperature were repeated. The maximum draw ratio was 40 for the films prepared from the gels of high molecular weight (HMW) a-PVA ( D P = 12000)/water/dimethyl sulfoxide (DMSO) system (water/DMSO = 20/80). The degree of crystallinity of the dried gels prepared from the PVA/ethylene glycol (EG) system was high, 40-50%, and independent on the tacticity of PVA. The modulus of the fibers, prepared from the gels of HMW s-PVA ( D P = 15300)/EG system, drawn 15 times to its original length was the highest ( 120 GPa) .
SYNOPSISThe color development due to the complex formation of poly(viny1 alcohol) (PVA) with iodine increased with increasing syndiotacticity of PVA. Isotactic PVA showed no color development. The color development of syndiotacticity-rich PVA film decreased with increasing annealing temperature for films before complexization, whereas that of atactic (commercial) PVA increased with it. Lower temperatures, the elongation of complex film, and the presence of boric acid enhanced the absorbance at 600 nm due to I;. The complexes are assumed to be made by incorporation of polyiodines into aggregates of syndiotactic sequences in PVA. The polarizability and electric conductivity of complex films are investigated. 0 1993 John Wiley & Sons, Inc.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.