Changes in physical properties of methacrylonitrile (MAN)‐grafted silk fibers

Abstract

SYNOPSISChanges in physical properties of silk fibers, grafted with methacrylonitrile (MAN), were investigated as a function of the weight gain. The weight gain increased steadily during the first 60 min of reaction and gradually attained an equilibrium value (60% ) after about 4 h. The initial tensile resistance of silk fibers decreased by MAN grafting. The crystalline structure of silk fibers remained unchanged, regardless of MAN grafting, however, a minor and broad peak appeared in the X-ray diffraction curves of MAN-grafted silk fibers with a weight gain of 60%, corresponding to the unoriented MAN polymer attached inside the fibers. Molecular orientation of silk fibroin chains in the crystalline regions, evaluated from X-ray diffraction curves, did not change significantly, while both birefringence and isotropic refractive index decreased as the weight gain increased, implying that MAN polymer attached preferentially to the amorphous and not t o the crystalline regions. Dynamic viscoelastic measurements showed that the position at which the E' value began to decrease shifted to a lower temperature as the weight gain increased. These findings suggest that the thermal movement of silk fibroin molecules was accelerated by the presence of the poly-MAN chains attached to the amorphous regions of silk fibroin fibers. 0 1993 John

Silk grafting with methacrylic monomers: Process optimization and comparison

“…[8][9][10] Many works on silk grafting have been developed using various vinyl monomers: styrene, 11 acrylamide, 2 methacrylamide, 3,4,10,[12][13][14][15][16][17][18][19][20] N(nbutoxymethyl)methacrylamide, 21,22 methacrylonitrile, 23,24 vinyltrimethoxysilane 25 and several methacrylates: methyl-, [4][5][6][7][8]20,24,[26][27][28][29] ethyl-, 24 isopropyl-, 10 n-butyl-, 30 benzyl-, 31 glycidyl-, 2 2-hydroxyethyl-, 3,4,9,10,18,19,32 ethoxyethyl-methacrylate. 33 Methacrylamide (MAA), however, is the monomer most used in industry because it gives products with soft hand, crease recovery (up to 30% weighting), and increased hygroscopicity.…”

Silk‐inspired polyurethane containing glyalaglyala tetrapeptide. III. morphological, thermal, and mechanical features of electrosprayed and electrospun deposition

“…About the glass transition temperature ( T g ) of silk fibroin, some are reported more than 170–180°C, others are reported −20–−30°C, and the T g depends on the absorbed moisture. For silk fibroin films prepared at ambient humidity (∼35%) the T g is ∼100°C while for water saturated films the T g is room temperature .…”

Physical properties of silk fibers grafted with a binary mixture of styrene and n‐butyl methacrylate

“…8 The surface of the treated silk fibers was examined, after gold coating, with a JEOL JAX-333s scanning electron microscope (SEM) at 15 kV acceleration voltage. Figure 1 shows the tensile strength and elongation at break of St/BMA-grafted silk fibers measured both in dry and wet states as a function of the amount of weight gain.…”