Structure and properties of tussah silk fibers graft-copolymerized with methacrylamide and 2-hydroxyethyl methacrylate

Abstract

Tussah silk fibers were graft-copolymerized with methacrylamide (MAA) and 2-hydroxyethyl methacrylate (HEMA) in aqueous media, using a chemical redox system as an initiator. High weight gain values were obtained with both grafting agents (up to 175%). The extent of homopolymerization was negligible for the MAA grafting system over the entire range of monomer-silk ratios examined, while polymer deposition on the fiber surface occurred when the HEMA-silk ratio exceeded 0.5% (w/w). The moisture content of poly(MAA)-grafted silk fibers was enhanced by grafting. Breaking load, elongation at break, and energy decreased at low weight gain (0-20%) and then remained rather constant. The DSC curves of poly(MAA)-grafted silk showed a new endotherm at about 280ЊC, due to the melting of poly(MAA) chains. The loss modulus peak of poly(HEMA)-grafted silk fibers broadened and shifted to a lower temperature, showing a tendency to split into two peaks at high weight gain. On the other hand, grafting with poly(MAA) induced a noticeable upward shift of the loss peak. The TMA curves showed that grafting with poly(MAA) resulted in a higher extent of fiber contraction from room temperature to about 250ЊC. Moreover, the intensity of the final contraction step at about 350ЊC decreased with increasing weight gain and shifted to a lower temperature. The Raman spectra of grafted fibers were characterized by overlapping of the characteristic lines of both silk fibroin and polymer, the latter showing an intensity proportional to the amount of weight gain. Among the conformationally sensitive vibrational modes of tussah silk fibroin, the amide III range was significantly modified by grafting with both poly(MAA) and poly(HEMA).

Grafting of methyl methacrylate onto natural keratin

“…Different studies have shown that grafting may cause slight or severe changes in the thermal behavior of the fibers, the extent of which depends on several parameters, such as the kind of used monomer, grafting conditions and grafting percentage [5][6][7]. The results of DSC are summarized in Fig.…”

“…For instance, silk crease recovery, dimensional stability, rub resistance, photo yellowing, oil and water repellency, color fastness, have been dramatically improved [5,6] by means of grafting. In the case of wool, the internal deposition of different polymers may change tensile properties, felting shrinkage, abrasion and pilling resistance, hygroscopicity, chemical resistance, thermal stability, dying behavior, rot resistance, durability and bacterial resistance [7,8].…”

Development of advanced antimicrobial and sterilized plasma polypropylene grafted muga (antheraea assama) silk as suture biomaterial

“…The peaks at 2405 and 2108 cm −1 represent characteristic α‐helical and β‐sheet conformation of AASF . Besides, the spectral patterns are further characterized by the peaks at 1665 (amide I), 1234 (amide III), and 1083 cm −1 which are assigned to β‐sheet conformation whereas the peaks at 1058, 945, and 906 cm −1 arise from α‐helical conformation of fibroin region containing polypeptide (poly(‐Gly‐Ala) chain) sequences . From Figures a–c, it appears that position and intensity of the peaks characteristics of β‐sheet AASF remain essentially unchanged.…”

Evaluation of the mechanical properties of chemically modified chicken feather fibres reinforced high density polyethylene composites

“…They are also hydrophobic and hygroscopic in nature with unique honeycomb structure which is accountable for their high thermal resistance properties [15]. CFF can be modified by grafting to enhance some of its naturally poor properties such as dimensional stability, rub resistance, oil and water repellency, tensile properties, abrasive and peeling resistance [16][17][18][19]. CFF have been used to reinforce a number of different polymeric materials for diverse applications.…”