Grafted Silk Fibers Research Articles

The preparation of poly[N(n‐butoxymethyl) methacrylamide] grafted silk fibers by polymerization using a low pH system

AbstractThe graft polymerizations of the N(n‐butoxymethyl) methacrylamide (BMA) monomer onto silk fibers were effected after reducing the pH of the grafting system to 2.5 by the addition of a formic acid solution. We compared the grafting efficiencies, surface characteristics, and thermal behaviors, as well as the whiteness levels and the extent of reduction of the rate of yellowing following UV irradiation, with the equivalent features of poly(BMA)‐grafted silk fibers, prepared under normal (pH 6) conditions. The grafting efficiency [as poly(BMA) weight gain] onto silk fiber that was attained was almost 100% through optimization of the pH environment in the polymerization system by the addition of formic acid. The stiffness of the silk fabrics observed, following the conventional grafting, was markedly higher than that of equivalent silks after the polymerization at pH 2.5. The rates of yellowness index increase, for these latter silk fabrics following UV irradiation were also reduced, specifically in the initial irradiation period (up to 60 h).The SEM of the grafted silk fabrics reveal the absence of granules on the surface of the grafted silk fiber, when the silk was grafted with poly(BMA), after reducing the pH of the grafting system to 2.5. These findings suggest that the BMA monomer was polymerized specifically within the silk fiber and not on the surface. It is suggested that the increase in the polymer weight gain, and the reduced adverse effect on the fabric handle, arise because of the modified polymer location. © 1993 John Wiley & Sons, Inc.

Reductions in rate of yellowing following irradiation of poly[N(n‐butoxymethyl) methacrylamide]‐grafted silk fibers

AbstractThe physical properties, including changes in the yellowness index, following UV irradiation of Bombyx mori silk fibers loaded with poly[N(n‐butoxymethyl) methacrylamide], poly(BMA), are examined in relation to the amount of held polymer. The percentage weight gain by the silk fibers observed after 45 min at 80°C increased with increasing initial amounts of BMA monomer in the reaction system. Differential scanning calorimetry (DSC) observations suggest that the thermal decomposition behavior of the heated silk fiber was little affected, with but an apparent small shift of the endothermic decomposition temperature range to higher temperatures. The tensile properties of the treated silk fibers remained effectively unchanged, independent of the polymer weight gains. There was, however, a marked effect of the poly(BMA) weight gains onto silk in maintaining the whiteness and reducing the rate of yellowing following irradiation of treated habutae silk fabrics. These observations suggest that the rate of photoyellowing of silk fabrics can be retarded by the presence of the poly(BMA) in the fabric. © 1993 John Wiley & Sons, Inc.

Grafting of methyl methacrylate onto silk fibers initiated by tri‐n‐butylborane

AbstractStructural characteristics of the methyl methacrylate (MMA)‐grafted silk fibers using tri‐n‐butylborane as an initiator were analyzed by infrared spectroscopy and differential scanning calorimetry (DSC), and their refractive index and tensile properties were measured. Graft polymerization was promoted by FeCl3 pretreatment of the silk. The graft yield reached a maximum by the immersion in 4% FeCl3 solution for 1 min at 25°C. The infrared spectrum of poly(MMA)‐grafted silk fibers showed overlapped absorption bands of silk fibroin with the β structure and of the grafted MMA polymer. A grafted silk fiber with graft yield of more than 140% exhibited two endothermic peaks at 321°C and 396°C on the DSC curve, attributed to the thermal decomposition of silk fibroin and grafted poly(MMA) chain, respectively. Refractive index measurements suggested that the molecular orientation and the crystallinity of the silk fiber decreased with increasing graft yield. Electron photomicrographs showed that silk was coated by grafted PMMA. The tensile strength of the grafted silk decreased rapidly by the grafting even at a lower level.

Structural characteristics of 2‐hydroxyethylmethacrylate (HEMA)/methacrylamide (MAA)‐grafted silk fibers

AbstractA series of 2‐hydroxyethylmethacrylate (HEMA)/methacrylamide (MAA)‐grafted silk fibers obtained in various comonomer compositions was prepared and their structural characteristics were studied by X‐ray diffractometry, differential scanning calorimetry, and scanning electron microscopy. HEMA/MAA‐grafted silk fibers with a graft yield of about 60% obtained in a HEMA/MAA mixture system containing 20% of HEMA and 80% of MAA on a weight basis showed endothermic peaks at 280 and 420°C (shoulder form), which are attributed to the thermal decomposition of the MAA and HEMA polymers, respectively, in addition to the thermal decomposition peak of the silk fibroin fiber which appeared at 323°C. These DSC results suggest that the HEMA/MAA‐grafted silk fiber showed a low compatibility in the relation between the silk fibroin molecules and HEMA and/or MAA polymers. The crystalline structure of the HEMA/MAA‐grafted silk fiber remained unchanged regardless of the HEMA/MAA grafting ratio even when the graft yield value reached 120%.

Studies on some physical properties and structural characteristics of methyl methacrylate‐grafted silk fiber

AbstractStructural characteristics and physical properties of methyl methacrylate‐grafted silk fiber from Bombyx mori were studied by X‐ray diffractometry, differential scanning calorimetry (DSC), thermogravimetry, and scanning electron microscopy. Methyl methacrylate (MMA)‐grafted silk fiber with a grafting yield of more than 30% showed two endothermic peaks at 320°C and 390–410°C, which are attributed to the thermal decomposition of silk fibroin and MMA polymer filled in the fiber, respectively. These DSC results indicate that MMA‐grafted silk fiber showed a poor compatibility in the relation between the silk fibroin molecules and MMA polymer. The weight of the MMA‐grafted silk fiber decreased as observed at 160°C on the thermogravimetric thermograms due to the evaporation of water from the sample with increasing graft yield. The crystalline structure of MMA‐grafted silk fiber remained unchanged regardless of MMA grafting. Taking into account the X‐ray diffraction patterns and the increasing graft yield with reaction time, it is assumed that the graft chains of MMA polymer have penetrated into a weak aggregate region and not in the crystalline region of silk fibroin.

Determination of water in grafted silk fibers by pyrolysis-gas chromatography

Determination of water in grafted silk fibers by pyrolysis-gas chromatography

The changes of Infra-red absorption spectra by autoclaving on the methacrylamide monomers grafted silk fibers and its applications for the testing of the grafted silk fibers

The changes of Infra-red absorption spectra by autoclaving on the methacrylamide monomers grafted silk fibers and its applications for the testing of the grafted silk fibers

Studies on dyeing properties of styrene grafted silk fiber

Studies on dyeing properties of styrene grafted silk fiber

Studies on dyeing properties of styrene grafted silk fiber

Studies on dyeing properties of styrene grafted silk fiber

Studies on dyeing properties of styrene grafted silk fiber

Studies on dyeing properties of styrene grafted silk fiber

Studies on dyeing properties of styrene grafted silk fiber

Studies on dyeing properties of styrene grafted silk fiber

Studies on dyeing properties of styrene grafted silk fiber

Studies on dyeing properties of styrene grafted silk fiber

Studies on dyeing properties of styrene grafted silk fiber

Studies on dyeing properties of styrene grafted silk fiber