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  • 1
    Electronic Resource
    Electronic Resource
    Structure and physical properties of epoxide-treated tussah silk fibers (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 44 (1992), S. 2203-2211 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The structural characteristics and physical properties of epoxide-treated tussah silk fibers from Antheraea pernyi silkworm are discussed in relation to the increasing weight gain values. Ethyleneglycol diglycidylether (E) and glycerin diglycidylether (G) were used as modifying agents. The noticeably high weight gain values (about 140%) obtained were attributed to the catalytic effect of SCN- anion absorbed by the fibers during the pretreatment under reduced pressure conditions. The amino acid analysis showed that epoxide G exhibited a slightly higher reactivity toward tyrosine, while arginine preferably reacted with epoxide E. The peak of loss modulus (E″) determined by dynamic viscoelastic measurements became broader and its position linearly shifted to lower temperature when the weight gain increased, and a minor peak appeared in the low-temperature region below 50°C. Differential scanning calorimetry (DSC) thermograms showed that the position of the decomposition peak of modified silk fibers shifted to lower temperature with increasing weight gain values. The minor and broad endothermic peaks, appearing in the reference sample at about 234 and 290°C, disappeared by epoxide treatment. X-ray diffraction patterns of tussah silk fibers suggested that the epoxide treatment does not affect directly the crystalline regions but causes a decrease of molecular orientation in the amorphous regions. Both briefringence (Δn) and isotropic refractive index (niso) of tussah silk fibers decreased by the reaction with epoxides, although with different rate and extent, confirming the decrease of average molecular orientation. The extent of decrease of strength and elongation depends on the kind of epoxide and on the weight gain value. Epoxide-treated tussah silk fibers did not show significant changes of surface characteristics as the weight gain values attained up to 60%.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1992.070441217
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  • 2
    Electronic Resource
    Electronic Resource
    Chemical modification of silk with itaconic anhydride (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 45 (1992), S. 1719-1725 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Bombyx mori silk fibers were chemically modified by acylation with itaconic anhydride. The reactivity of the modifying agent toward silk fibroin was investigated on the basis of the amino acid analysis. We examined the physical properties, the structural characteristics, and the thermal behavior of modified silk fibers as a function of the weight gain. Silk fibers with a weight gain of 9%, corresponding to an acyl content of 68.9 mol/105g, were obtained at the optimum reaction conditions for silk acylation (75°C for 3 h). The amount of basic amino acid residues (Lys, His, and Arg) decreased linearly as the weight gain increased. The alkali solubility increased proportionally with the weight gain, probably due to the dissolution of the modifying agent reacted with silk fibroin, and not to the degradation of the fibers induced by the chemical modification. The birefringence value, related to the molecular orientation, slightly decreased when the weight gain increased. The isotropic refractive index, associated with the crystallinity, increased when the weight gain ranged from about 5 to 7% and then remained unchanged. The moisture regain did not change regardless of the chemical modification, and the crease recovery behavior of modified silk fabrics did not show significant improvement. The thermal behavior of silk fibers was affected by the modification with itaconic anhydride. The decomposition temperature shifted up to 322°C, 10°C higher than the control silk fibers, suggesting a higher thermal stability induced by chemical modification.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1992.070451005
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  • 3
    Electronic Resource
    Electronic Resource
    Physical properties of 2-hydroxyethyl methacrylate-grafted silk fibers (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 49 (1993), S. 1835-1844 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: This paper deals with the physical properties of silk fibers grafted with 2-hydroxyethyl methacrylate (HEMA). Both tensile strength and elongation measured in the dry and wet states gradually decreased with increasing weight gain. The initial modulus of the grafted silk fibers in the dry state sharply increased in the weight gain range of 0-16%, then decreased to a lower value than the reference untreated sample. The refractive indices parallel and perpendicular to the fiber axis decreased, though the former showed a steeper slope. Accordingly, birefringence and isotropic refractive index also decreased, suggesting a lower degree of crystallinity and molecular orientation of grafted silk fibers. DSC, TMA, and TGA curves of the HEMA-grafted silk fibers indicated an increased higher thermal stability of silk fibers due to the HEMA grafting. The dynamic mechanical measurements showed that the thermally induced molecular movement of both amorphous and crystalline domains of silk fibers was enhanced by HEMA grafting. X-ray diffraction curves, however, implied that the crystalline structure of the silk fibroin remained unchanged regardless of HEMA polymerization. The introduction of HEMA polymer in silk fibers was evidenced by the infrared spectra, exhibiting the absorption bands characteristic of either the grafted HEMA polymer and the fibroin molecules with ordered β structure. © 1993 John Wiley & Sons, Inc.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1993.070491014
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  • 4
    Electronic Resource
    Electronic Resource
    Chemical structure and dynamic mechanical behavior of silk fibers modified with different kinds of epoxides (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 52 (1994), S. 1037-1045 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The chemical reactivity of epoxide molecules toward silk fibroin was investigated by determining the rate of conversion of reactive amino acid residues. Significant differences were found between two different bifunctional epoxides, diglycidyl ethers of ethylene glycol (E) and resorcinol (R), the former reacting at a higher extent with arginine and tyrosine. The moisture regain decreased by reaction with epoxides, at a variable rate and extent, according to the hydrophobic/hydrophilic properties of epoxides. A two-step behavior was observed when moisture regain values relating to the silk content in modified silk, fibers were plotted as a function of the weight gain. Dynamic mechanical data showed that the major loss peak became broader and its temperature shifted to lower values following the increase of weight gain. The loss peak temperatures showed a linear relationship with the amount of weight gain. The fine structural changes induced by reaction with eposides will be discussed in terms of chemical and steric factors of the epoxides, as well as of epoxide location within the different structural domains of silk fibers. © 1994 John Wiley & Sons, Inc.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1994.070520805
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  • 5
    Electronic Resource
    Electronic Resource
    Structural characteristics of wool fiber modified with itaconic anhydride (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 46 (1992), S. 1477-1483 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The physicochemical properties of wool fibers chemically modified with itaconic anhydride in dimethylformamide were analyzed by DSC, TMA, and TGA and on the basis of measurements of the tensile characteristics. The acyl content in wool fiber increased even at the comparatively low reaction temperature (65°C) compared with that in silk fiber; this fact was due to the larger number of reactive sites in the wool than in silk such as basic amino acid residues. On the basis of DSC, TMA, and TGA analyses, the high thermostability of the modified wool fiber was evident. The molecular orientation, evaluated from the birefringence measurement, decreased slightly after the modification; however, tensile properties and surface characteristics of the wool fiber were not damaged. © 1992 John Wiley & Sons, Inc.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1992.070460819
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  • 6
    Electronic Resource
    Electronic Resource
    Reductions in rate of yellowing following irradiation of poly[N(n-butoxymethyl) methacrylamide]-grafted silk fibers (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 48 (1993), S. 113-120 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The 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.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1993.070480112
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  • 7
    Electronic Resource
    Electronic Resource
    Physical characteristics of silk fibers modified with dibasic acid anhydrides (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 51 (1994), S. 345-352 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The objective of this study was to investigate the physical properties of silk fibers modified with dibasic acid anhydrides. These are potentially attractive modifying agents to reduce the rate of photoyellowing of silk during and following UV irradiation. Several analytical techniques were employed, which included the measurement of the basic mechanical properties (tensile strength and elongation at break), equilibrium regain, amino acid analysis, dynamic viscoelastic measurements, X-ray diffractometry, and scanning electron microscopy (SEM). The succinylated silk fibers, which have been conditioned under different relative humidity atmospheres, always exhibited slightly higher equilibrium regain values than those of equivalently conditioned glutarylated silks. The amount of the basic amino acid residues slightly decreased following modification with both succinic and glutaric anhydrides. The birefringence values and the isotropic refractive indices decreased only slightly, which suggests that the fine structure of the treated silk fibers was not significantly altered. The X-ray diffraction curves demonstrated that no changes in the crystalline structure were induced by reaction with dibasic acid anhydrides. The tensile properties of the modified silks remained more or less unchanged. Only the initial tensile resistance of glutarylated silks in the dry state significantly decreased. The dynamic viscoelastic behavior of modified silk fibers was characterized by a reduced thermal stability. In fact, the onset temperature of the prominent E peak corresponding to the molecular movement shifted to lower values. The surfaces of modified silk fibers were as smooth as that of the untreated control sample. © 1994 John Wiley & Sons, Inc.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1994.070510217
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  • 8
    Electronic Resource
    Electronic Resource
    Dyeability of silk fabrics modified with dibasic acid anhydrides (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 52 (1994), S. 769-773 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Silk fabrics were chemically modified with different kinds of dibasic acid anhydrides. Samples with different acyl contents, ranging from 24 to 107 mol/105g, were obtained by reaction with succinic (S), glutaric (G), phthalic (PA), and 0-sulfobenzoic (OSBA) anhydrides. Dyeability with a cationic dye (Rhodamine B, C.I. Basic Violet 10) was determined by measuring dye uptake and K/S values. Following acylation, the absorption of basic dye was significantly enhanced for all samples. The maximum dye uptake was attained by OSBA-treated silk fabrics, while samples treated with S. G. and PA did not differ significantly. Dye uptake increased regardless of the content, at least in the range examined. Reflectance measurements and K/S values confirmed the trend evidenced by dye uptake results. © 1994 John Wiley & Sons, Inc.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1994.070520607
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  • 9
    Electronic Resource
    Electronic Resource
    Physical properties and dyeability of NaOH-treated silk fibers (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 55 (1995), S. 481-487 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Domestic (Bombyx mori) and wild (tussah, Antheraea pernyi) silk fabrics were treated with diluted NaOH solutions by the pad/batch method. The equillbrium moisture regain of tussah silk fibers increased steadily with alkaline treatment, while that of B. mori did not change. B. mori tensile strenght and elongation at break were slightly impaired. The average molecular orientation and crystallinity of both kinds of silk remained unchanged. Differential scanning calorimetry (DSC) and thermomechanical analysis(TMA) showed that the thermal behavior of B. mori silk was almost unaffected, while that of tussah exhibited slight changes in the temperature range 250-300°C. By dynamic mechanical measurements (DMA) it was elucidated that both storage and loss moduli of B. mori silk fibers decreased following NaOH treatment. On the other hand, tussah silk exhibited a noticeable upward shift of the major loss peak. Alkali-treated tussah silk fibers, dyed with an acid dyestuff, attained a lower degree of dye-bath exhaustion. © 1995 John Wiley & Sons, Inc.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1995.070550313
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  • 10
    Electronic Resource
    Electronic Resource
    Structural characteristics of silk fibers treated with epoxides (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 43 (1991), S. 643-649 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Structural characteristics of the silk fibroin fiber-modified with epoxide treatment were elucidated by refractive index measurement, differential scanning calorimetry, and thermomechanical analysis and on the basis of strength-elongation measurements. The four epoxides used were glycidol (G), ethylene glycol diglycidyl ether (E), tolyl glycidyl ether (T), and resorcinol diglycidyl ether (R). The values of the isotropic refractive index of the silk fiber increased by the action of T or R. The position of the endothermic peak attributed to the thermal decomposition and the position of the onset of the contraction of each of the samples treated with epoxides shifted to higher temperature, suggesting the more thermal stability. However, the values of the molecular orientation and the crystallinity of the specimen evaluated from X-ray diffraction analysis remained unchanged regardless of the epoxide treatment. These experimental results have been interpreted in terms of the cross-links between the adjacent silk fibroin molecules and of the hydrogen bonds between the hydroxyl groups of the epoxide molecules attached to the side chains of the silk fibroin.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1991.070430403
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