Papers by Keyword: Graft Copolymerisation

Abstract: Activated starch was prepared by ball milling before used. Graft copolymerization of acrylamide onto activated starch was carried out in inverse emulsion using a redox initiation system of ammonium persulfate and sodium bisulfite. The effects of ball-milling time, reaction temperature, initiator concentration and weight ratio of acrylamide to starch on the conversion of monomer, grafting percentage and grafting efficiency were studied. The structure and properties of the graft copolymer and activated starch were characterized by FT-IR, XRD and SEM. The results showed that ball milling could progressively destroy the crystalline structure of starch and improve the chemical reactivity. The monomer conversion, grafting percentage and grafting efficiency of grate copolymerization were 96.6%、62.4%、85.49%, respectively.

Abstract: Abstract. In this paper, high oil-absorbing resin is prepared, using microcrystalline cellulose as base material, and acrylate as grafting monomer. Effect of mass ratio of microcrystalline cellulose/monomer, the amount of cross-linking agent, initiator dosage, reaction temperature, and reaction time on oil-absorbing properties of the products is investigated. The optimized conditions are as followed: reaction time 6 hours, reaction temperature 70 °C, mass ratio of microcrystalline cellulose to monomer 1:1.5. The oil absorbing ratio of the product prepared under these conditions is up to 12.9 g/g for toluene, and 14.6 g/g for kerosene oil.

Abstract: The chloroprene rubber (CR) and trans isoprene rubber (TPI) combined with methyl methacrylate (MMA) and α-Methylacrylic acid (MAA) to obtain a tetrabasic graft copolymer adhesive in a low poisonous mixing solvent. The effect of solvent, ratio of CR and TPI, benzoyl peroxide (BPO) amount, the dosage of MMA and MAA on the adhesive properties was investigated by studied the relationship between graft percentage (GP) and the T peel strength (T-PS) of various graft copolymer adhesives. The results showed that an excellent tetrabasic graft copolymer adhesive was obtained by a copolymerization of CR, TPI, MMA and MAA was 85 g, 15 g, 0.8 g, 60 g and 10 g using 0.8g BPO as initiator in a low poisnouos mixing solvent consisted of 124 g ethyl acetate (EA), 44 g pyroacetic spirit (PK) and 32 g toluene (TOL) at 85 °C for 5 h. The chemical structure of the tetrabasic graft copolymer adhesive was characterized by FTIR.

Abstract: The chitosan was degraded by hydrochloric acid and the effects of concentration of chitosan, amount of hydrochloric acid, reaction temperature and reaction time on the viscosity of chitosan were investigated. The results showed that the degraded chitosan with low viscosity could be prepared when chitosan (wt 6%) was dissolved in acetic acid solution and hydrochloric acid (wt 3%) at 90°C for 6 h to decrease the viscosity from 7.52 mPa·s to 2.48 mPa·s. Then, a graft copolymer was synthesized by copolymerization of degraded chitosan with methacrylic acid (MAA) and acrylamide (AAM) by using horseradish peroxidase (HRP)/H₂O₂/acetylacetone (ACAC) as initiator. The structures of original chitosan, degraded chitosan and the copolymer were characterized by FTIR. The copolymer was applied to the leather industry as an amphoteric retanning agent. The applied results showed that the retanned leather had the merits of good uniformity fullness softness, strong selecting filling properties, good dyeing ability and antimicrobial activity.

Abstract: Graft copolymerization of diethylenetriamine onto bagasse celluloses was investigated with ammonium ceric nitrate as initiator in an aqueous medium. The condition of the graft copolymerization initiator concentration, the mass ratio of monomer/cellulose, reaction temperature, reaction time based on the experiment is optimized according to the zeta potential. The results showed the relative optimum process conditions were: the concentration of initiator at 36.98mmol/L, the mass ratio of the monomer and cellulose at 1:1, the reaction temperature at 70°C, and the reaction time by 3h. In addition, the graft copolymers were characterized by Fourier transform infrared spectra (FT-IR), X-ray diffraction analysis (XRD). The results showed that bagasse celluloses could be grafted with diethylenetriamine in aqueous medium.

Abstract: The Pb( )-imprinted polymers were synthesized through homogeneous graft copolymerization of cellulose with acrylic acid in an homogeneous medium using Pb( ) as template. The prepared copolymers were characterized by FTIR and SEM. The batch adsorption experiments were conducted to evaluate the adsorption capacity of the Pb( )-imprinted beads. The results demonstrated that the imprinted beads showed significantly higher imprinting efficiency than those only consisting of poly(acrylic acid) without Pb( )-imprinted, and the selectively adsorption capacity of Pb( ) on imprinted beads was higher than other competitive ions(Cu( ) or Ni( )). The imprinted beads also showed much better stability in rebinding of the imprinted ions after three adsorption-regeneration cycles.

Abstract: Graft copolymerization of acrylic acid(AA) on starch to prepare super absorbent resin (SAR) under microwave irradiation were investigated using N,N-methylene bis-acrylamide as crosslinker and potassium persulfate as initiator. The influences of the amount of initiator and crosslinker, neutralization degree of acrylic acid(AA), ratio of starch to AA, microwave power level and irradiation time on the distilled water absorption amount of resin were investigated. The results indicated that it only needed 4min under the microwave level of 231W to obtain the resin with the maximum absorption amount of 1110g×g^-1, under the conditions that 0.3wt% initiator, 0.02wt% crosslinker, 60% neutralization degree of acrylic acid, the ratio of starch to acrylic acid of 0.25. Under microwave irradiation, the synthesis and drying of super absorbent resin could be completed at one step without nitrogen. Compared to conventional heating method, the methods had the striking advantages of short reaction time, simple process and low cost.

Abstract: In this article, the graft copolymerization of 4-vinyl pyridine onto poly (ethylene terephthalate)(PET) via the potassium diperiodacuprate(III)–PET redox system as an initiator was investigated in an alkaline medium. The graft copolymer was characterized with Fourier-transform infrared spectra analysis. A mechanism is proposed to explain the generation of radicals and the initiation. The effects of reaction variables, such as the initiator concentration, the ratio of monomer to PET, pH, and reaction temperature and time, are investigated, and the grafting conditions are optimized. Graft copolymers with high grafting efficiency are obtained, thus indicating that potassium diperiodacuprate(III)-PET redox system is an efficient initiator for this graft copolymerization. The quaternized PET-g-PVP (QPEVP) is proved to be an excellent adsorbent to heavy metal ions.

Abstract: Chitosan-g-MMA was prepared with methyl methacrylate using ceric ammonium nitrate (CAN) as an initiator under nitrogen atmosphere in aqueous solution and characterized by FTIR spectroscopy. The effects of concentration of CAN, the amount of MMA, reaction temperature on graft copolymerization were studied by determining the grafting percentage and grafting efficiency. The maximum grafting percentage and grafting efficiency obtained under these conditions were 790 % and 83 %, respectively.

Abstract: In aqueous two-phase system, azodiisobutyronitrile（AIBN） was adsorbed on starch by dissolve- precipitate method. Free radical was then produced by its thermolysis, thus graft copolymerization of starch and acrylamide could be initiated. The effect of factors such as initiating system, organic solvent for AIBN dissolving, time for pre-initiation, concentration of initiator, composition and concentration of disperse system on monomer conversion, grafting efficiency, and dissolution property of the reaction product were studied. The optimum conditions of the reaction were as follows: AIBN was used as initiator and methanol as solvent; pre-initiation time was 25 min; concentration of AIBN was 2.6×10^-4 mol/L; polyethylene glycol (PEG) and polyvinyl alcohol (PVA) was used as disperse system, the ratio of m(PEG):m(PVA) was 2.0:1 and their total mass fraction was 6.5%; both pre-initiation and polymerization temperatures were 60-65 °C. Monomer conversion (C) and grafting efficiency (GE) of the product obtained under these conditions were 99.4% and 99.1%, respectively.