Papers by Keyword: Graft Copolymer

Abstract: In this study, the modification of starch was conducted through graft copolymerization of cinnamic acid to result in starch-g-poly(cinnamic acid). The cinnamic acid polymerization was carried out via radical polymerization using cerium ammonium nitrate (CAN) as an initiator. The viscosity of the graft copolymer 10000 ppm dissolved in 16% NaOH solution was measured at a temperature range of 25-75 °C. The results showed that the higher the temperature the lower the viscosity. The activation energy of viscous flow for the copolymer was 18.4 kJ.mol^-1. The viscosity values of the copolymer solutions were also measured in saline solutions with NaCl contents of 3−20%(w/v). For the measurements in these saline solutions, the highest viscosity was 3.39 cP at room temperature for the copolymer solution containing 5%(w/v) NaCl.

Abstract: Polystyrene-grafted natural rubber (PS-GNR) at various graft levels was evaluated to improve mechanical properties of natural rubber (NR). PS-GNR was synthesized by emulsion copolymerization at 60°C at different reaction times between 15 and 360 mins to control the grafting levels of PS in the PS-GNR co-polymer. The resultant PS-GNR co-polymers were then blended into NR latex. The vulcanized NR compounds were investigated for the effect of PS grafting percentage in PS-GNR/NR compounds on mechanical properties, including tensile, tear strength and hardness. A core-shell structure was revealed with PS encapsulating the NR core via transmission electron microscopy. The polystyrene grafting percentage was determined to be 12.7%, 17.1%, 22.1% and 23.6% for polymerization times of 15 min, 60min, 120min, and 360 min, respectively. Addition of PS-GNR into NR exhibited biphasic behavior, resulting in a decrease in the tensile strength and tear strength. With further increase in grafting percentage of PS, the tensile strength and tear strength continues to decrease. The rigid chain of PS grafted onto NR surface reduced the elasticity of NR chain resulting in lower tear strength and the tensile strength. Fracture surface revealed a decrease in ductility of material with increasing grafting percentage of PS. On the other hand, modulus and hardness of PS-GNR/NR compounds were found to increase with increasing grafting percentage of PS. The addition of PS-GNR to rubber compound had shown an impact on dynamic behavior. With further increase in grafting percentage of PS in PS-GNR, an enhancement of storage modulus of rubber compound was clearly observed.

Abstract: Cinnamic acid grafted carboxymethyl cellulose (CMC-g-P (CA)) has been synthesized by microwave assisted technique, which is an alliance of microwave radiation with chemical free radical initiator (CAN) to commence grafting. The novel graft copolymer has been characterized by physicochemical techniques – FTIR spectroscopy, intrinsic viscosity measurement, elemental analysis (C, H and N), SEM micrograph and TGA study. The flocculation efficacy and range of turbidity during the sedimentation stage for synthesized material has been investigated in kaolin suspension by ‘Jar test’ procedure. The optimal dosage of CMC-g-P (CA) as flocculant in kaolin suspension is at 10 ppm and it showed lowest range of turbidity (176-61 NTU) during sedimentation stage.

Abstract: Graft copolymers of natural rubber with itaconic anhydride (IA) were prepared in toluene using benzoyl peroxide (BPO) as an initiator. The effects of reaction temperature, reaction time, monomer concentration and initiator concentration on natural rubber grafting were investigated. Graft copolymers (NR-g-IA) were characterized by Fourier transform infrared spectroscopy (FTIR). The grafting content of IA onto NR was estimated by means of FTIR using the absorbance peak ratio for 1783 cm^-1 and 835 cm^-1, corresponding to the symmetric C=O stretching and the =C-H out of plane bending in natural rubber, respectively. Titration was also used to determine the amount of IA grafted onto natural rubber. The optimal grafting conditions for preparation of NR-g-IA were found at 10 phr IA, 2.5 phr BPO, 85°C temperature, and 2.5 hr reaction time.

Abstract: Guar gum grafted sodium polyacrylate have been prepared via aqueous solution graft polymerization. Furthermore, the polymers were then surface-crosslinked using trimethylolpropane triglycidyl ether (TMPTGE) to improve the properties of swollen hydrogel. Polymerization conditions were systematically optimized to achieve the optimum swelling capacity. FTIR and DSC spectra confirmed that sodium acrylate had been grafted onto guar gum chains. SEM observations showed morphology of the samples. The results confirmed that introducing guar gum into the superabsorbent could improve the swollen hydrogel mechanics performance, including hydrogel strength, resilience and dispersion, although making the water absorbency decreasing slightly. The good mechanics performance will make it feasible in hygiene application.

Abstract: The simultaneous graft copolymerization between natural rubber (NR) and styrene monomer (St) was induced by electron beam irradiation. The grafted polystyrene in graft copolymer was characterized by Fourier Transform Infrared Spectroscopy (FT-IR). This research investigated the influence of three factors (radiation dose, type of emulsifier and adding of sensitizer; normal butyl acrylate (n-BA)). It was found that the appropriated emulsifier was ammonium laurate which lead to higher monomer conversion and grafting efficiency. The adding of n-BA could notably enhance monomer conversion and crosslink density. Moreover increasing radiation dose, the monomer conversion and crosslink density increased. This technique was a cleaner and faster technology suitable for grafting application.

Abstract: Graft copolymer of styrene on natural rubber was prepared in laboratory by emulsion polymerization using potassium persulfate and sodium laurysulfate as an initiator and an emulsifier, respectively. The concentrations of initiator and emulsifier were varied in the range of 0.7 to 2.0 parts and 5.0 to 11.0 part per 100 parts of organic compositions, respectively. The gross polymers were purified by soxhlet extraction to remove ungrafted polystyrene and ungrafted natural rubber to obtain the graft copolymer (NR-g-PS). Characterization of graft copolymer was confirmed by FTIR spectroscopy. The results of the conversion, the kinetic rate of polymerization and grafting efficiency as a function of initiator and emulsifier concentration were studied. It was found that the conversion and the rate of polymerization increased with initiator and emulsifier concentration. At 1.0 parts of initiator and 5.0 parts of emulsifier were the optimum values. Therefore, the conversion and grafting efficiency can be used to predict the reaction conditions as a guideline for the graft copolymer production in pre-scale up reactor.

Abstract: The new high temperature resistance graft copolymer inhibitor based on starch and acrylic acid, 2-acrylamide-2-methyl propane sulfonic acid by solution polymerization reaction with self-made initiator. Laboratory evaluation experiment shows that a new scale inhibitor still has better effect， anti-scaling rate is 85.21%. The field test show that the dosage is 500ppm, the new high temperature resistance starch graft copolymer inhibitor by single well dosing, to solve problems of Xing-buried hills block and pipeline scaling and downhole ESP scaling.

Abstract: This paper, a comprehensive analysis of selective flocculation am fine hematite selected based on the combination of soluble starch and the characteristics of acrylamide was prepared soluble starch - grafting of acrylamide polymer flocculant. We can see through selective testing, the preparation of starch - acrylamide graft polymer of pure quartz and pure hematite were produced on the surface adsorption, through the measured absorbance and then converted to the concentration of ways we can see remnants of the graft material in the quartz very small amount of surface adsorption, while in hematite adsorption volumes. By hematite flocculation test we can see, with flocculants prepared by flocculation, its ability to better than selective flocculation modified maize starch and polyacrylamide.

Abstract: The synthetic methods that starch graft copolymerized with lactic acid have been preliminary studied with catalysis of ordinary chemical reagents by one-step, and the structure of starch/lactic acid graft copolymer was characterized by IRH-NMRXRD and SEM et al. The experimental results show that sodium hydroxide (NaOH), zinc oxide (ZnO) and stannous chloride (SnCl₂) so on can catalyze the graft copolymerization of starch with lactic acid successfully, it will provide a simple synthetic process to prepare starch/lactic acid graft copolymer.