Graft copolymerization of benzyl methacrylate onto wool fibers

Abstract

Benzyl methacrylate (BzMA) was graft copolymerized onto wool fibers by using ammonium peroxydisulphate as the initiator. Grafted samples with different polymer add ons (from 7 to 180%) were obtained by varying the monomer concentration in the reaction system. Following grafting with BzMA, the X-ray diffraction peak at 20.2Њ slightly moved towards higher spacing values. Birefringence decreased, indicating a lower degree of molecular orientation of grafted wool fibers. The equilibrium regain values of grafted wool decreased with increasing add on. Tensile strength increased in the range 45-77% add on, while elongation at break decreased. Differential scanning calorimetry (DSC) and thermogravimetry (TG) measurements showed a higher thermal stability for grafted wool. Following grafting, the drop of dynamic storage modulus (E) shifted to a lower temperature. Accordingly, the intensity of the loss modulus (EЉ) peak decreased, indicating that the thermally induced molecular motion was enhanced by grafting. Thermomechanical analysis (TMA) confirmed the increase in chain mobility for the grafted wool fibers. Above 35-40% add on, the presence of homopolymer on the surface of the wool fibers was identified by scanning electron microscopy.

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].…”

“…Free radicals can be produced by both chemical and physical methods, including the use of redox systems, oxidant agents or low and high-energy radiations [7]. A very effective method of generating free radicals under mild conditions is by one-electron transfer reaction, induced by redox initiation [9], which has been frequently used in grafting and polymerization.…”

“…Different studies on natural and modified wool fibers indicate that the preferred grafting sites are the thiol groups on cystine aminoacid [7,9]. However, NH and OH have also been found to act as reactive sites [11].…”

Pretreatments of Textiles Prior to Dyeing: Plasma Processing

“…They have used KMnO 4 as an initiator. Tsukada et al have used ammonium peroxysulfide as an initiator to graft benzyl methacylate on wool fibres (Tsukada et al, 1997). They have also reported that the tensile strength of grafted fibres increases while elongation and breaking strength decreases.…”