C. Rami Reddy

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.

Use of [13C]-NMR spectroscopy for the estimation of composition of ethyl acrylate/n-butyl methacrylate copolymers

Abstract Copolymers of ethyl acrylate (M 1 ) and n-butyl methacrylate (M 2 ) were prepared by benzoyl peroxide initiation in solution at 60° and copolymer compositions estimated by [ 13 C]-NMR spectroscopy. The kinetic behaviour is approximately ideal with r 1 = 1/ r 2 = 0.47. Relaxation times T 1 were determined for six of the carbons in M 2 units and one in the M 1 units; they range from 0.07 to 1.65 sec.

Dilute solution properties of methyl methacrylate—acrylonitrile copolymer (MA1)

This paper deals with studies on the dilute solution properties of methyl methacrylate—acrylonitrile copolymer of 0.289 mole fraction (mf) of acrylonitrile composition. Mark—Houwink parameters for this copolymer have been evaluated in acetonitrile (MeCN), 2-butanone (MEK), dimethylformamide (DMF) and γ-butyrolactone (γ-BL). The solvent power is found to be in the order of MEK < MeCN < DMF < γ-BL at 30°C. Herein, probably for the first time, the steric factor for the copolymer is found to be lower than that for the parent homopolymers and the excess interaction parameter, χAB is found to be negative. This probably suggests that the units are compatible to each other.

Graft copolymerization of 2-hydroxyethyl methacrylate and methyl methacrylate onto hide powder

Abstract Graft copolymerization of 2-hydroxyethyl methacrylate(HEMA) and mixtures of HEMA with methyl methacrylate (MMA) onto hide powder was attempted using ceric ammonium nitrate as initiator, with a view to optimize the conditions for graft copolymerization. Percent grafting and grafting efficiency were calculated for various variables such as monomer concentration, initator concentration and mole ratio of HEMA to MMA. R p , R g and R h (rates of polymerization, grafting and homopolymerization respectively) were also evaluated. It was observed that R p increased linearly with increasing concentration of MMA except at very low concentrations of the monomer. An explanation is given for the effect of variables on extent of grafting and grafting efficiency.

Graft co-polymerization of casein with acrylonitrile and n-butyl methacrylate

Casein was grafted using acrylonitrile and n-butyl methacrylate. The mechanical properties of the grafted co-polymer films were studied using an Instron Universal Testing Machine. The morphological characteristics were studied by scanning electron microscopy. The tensile strength was found to increase and elongation at break to decrease with increasing monomer content. The compatibility of the graft co-polymer and homopolymer formed was found to be important in governing the morphological features of the films.

Surface tension of polluted waters and treated wastewater

Abstract A comprehensive study was made on the measurement of surface tension of natural waters, artificially polluted waters, domestic wastewater, and effluents obtained by treating wastewater by different physical, chemical and biological methods. There was a significant negative correlation between the surface tension and the oxidisable organic matter (3 min PV) and a significant positive correlation between dissolved oxygen content and the surface tension. Oils and detergents reduced the surface tension of water to the minimum level. The biological treatment improved surface tension values to such an extent that the final quality resembled pure water. The vorticellid group of protozoa played an important role in the increase of surface tension of wastewater.

Thermal properties of polyurethanes cross-linked with chlorinated rubber graft copolymers

Abstract Polyurethane prepolymers, prepared from castor oil, propylene glycol (MW 2000) and toluene diisocyanate, have been cross-linked using a graft copolymer of chlorinated rubber (CR). The grafted chain is a terpolymer of n-butyl methacrylate (nBMA), ethyl acrylate (EA) and 2-hydroxyethyl methacrylate (HEMA). The glass transition temperature (T g ), thermal stability and degradation kinetics were evaluated for different urethane systems in which the proportion of graft copolymer and HEMA content (i.e. functionality) was varied. The broadening observed in the glass transition is assumed to be due to the effect of mixing of graft copolymer which functioned as a reactive diluent. The increase in T g is explained on the basis of total cross-link density and copolymer effect. In TGA, the major weight loss was observed in two stages in all the systems studied. Degradation was observed only above 225°C. The energy of activation (E) associated with the degradation of the networks was evaluated by expressions appropriate to degradation kinetics. The values of E so obtained are in good agreement with each other.

Influence of Monomer and Initiator Concentrations on the Simultaneous Grafting of Several Monomers onto Insoluble Collagen

Abstract Simultaneous grafting of 2-hydroxyethyl methacrylate and methyl methacrylate (3:1 and 3:2 mole ratios) onto insoluble collagen with ceric ammonium nitrate as initiator was attempted with a view to optimizing conditions for the preparation of hydrogels. The influence of monomer and initiator concentrations on the grafting reactions was investigated. The grafting results are discussed in the light of grafting efficiency and percentage of grafting. They were found to be lower when the 3:1 mole ratio of monomers was used.

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.