K. T. Joseph

Grafting of poly(glycidyl methacrylate) onto alginic acid

Abstract Grafting of poly(glycidyl methacrylate) (PGMA) onto alginic acid was carried out using ceric ammonium nitrate as initiator, using various concentrations of monomer and initiator, and various temperatures and times. Percentage grafting, grafting efficiency and rates of polymerization, graft copolymerization and homopolymerization were evaluated in all cases. Infrared spectra for pure alginic acid, poly(glycidyl methacrylate) and the alginic acid-poly(glycidyl methacrylate) were taken to establish the occurrence of grafting. Differential scanning calorimetry was carried out for alginic acid, poly(glycidyl methacrylate), the graft copolymer and the physical mixture to establish evidence for grafting.

Grafting onto naturally occurring macromolecules. Gelatin graft copolymers

Abstract Gelatin-methylmethacrylate copolymers were prepared using two initiators, viz. potassium persulphate and ceric ammonium nitrate. Grafting experiments were carried out at 60 and 70° using a short polymerization time (20 min) and a prolonged polymerization time (60 min). The composition of the graft copolymer depended upon the type of initiator and the experimental conditions. The number of grafting sites was small and the molecular weight of the grafted branches was very high. These results could be attributed to the heterogeneity of the system.

Studies on the grafting of acrylonitrile-co-styrene onto casein

Abstract Graft copolymerization of acrylonitrile and styrene mixture was performed on casein in aqueous medium at pH 7.8 using potassium peroxydisulphate as initiator. The effects of monomer concentration, initiator concentration and temperature were investigated. The individual polymers were isolated by Soxhlet extraction and characterized by i.r. spectroscopy and thermogravimetric analysis.

Graft copolymerization of ethyl acrylate on gelatin in water-acetic acid medium

Abstract Gelatin was graft copolymerized with ethyl acrylate in water-acetic acid medium (1:1. v/v). Effects of experimental variables such as reaction time and concentrations of monomer, initiator and gelatin were studied. The results are discussed in terms of rate of grafting and percentage of grafting. These quantities were found to be lower than for gelatin-g-poly(ethyl acrylate) copolymers in aqueous and water-isopropanol media.

Effect of additives on the cross section of PAN fibers

Abstract Additives are generally added to spin dope in wet spinning to facilitate mechanical operations, increase solid content, and effect gelation to precede phase separation. Besides these advantages, they have an effect on the cross section of PAN fibers. Organic compounds (hydrochlorides of aryl, alkyl secondary amines, etc.) change the cross section to a bean shape, whereas a nonsolvent (water) and inorganic compounds (calcium salts, borax, boric acid, etc.) retain the circular cross section of PAN fibers. The change in cross section can be attributed to the change in skin and core effects at different pH values of the spin dope in the presence of the additives.

Tensile properties of blends of copolymers of n-butyl methacrylate with ethyl acrylate and chlorinated rubber

Solution blending of n-butyl methacrylate-ethyl acrylate copolymers with chlorinated rubber was investigated. The tensile properties of the blends were studied; it was concluded that the blends serve as good film forming materials.