Increase In Grafting Percentage Research Articles

Development and characterization of dual sensitive poly(N,N-diethyl acrylamide) grafted alginate microparticles

Temperature and pH dual sensitive materials have attracted much interest in the fields of tissue engineering and drug delivery. In this study, a novel temperature and pH dual sensitive poly(N,N-diethyl acrylamide) grafted alginate (A-g-PDEA) microparticles were developed for 5-fluorouracil (5-FU) delivery. The structures of 5-FU loaded A-g-PDEA microparticles were characterized by FTIR, DSC, SEM, and XRD analyses. The effect of PDEA grafting percentage, temperature and pH on the swelling ratio and the release of 5-FU was explored. The obtained results displayed that the 5-FU release was controlled by both the temperature and pH of the medium. Furthermore, A-g-PDEA microparticles demonstrated a sustained release of 5-FU compared to free 5-FU. Moreover, the 5-FU release and swelling ratio of A-g-PDEA microparticles decreased with the increase in grafting percentage, crosslinking time and 5-FU/copolymer ratio. All the results indicated that A-g-PDEA microparticles are promising candidates for the sustained and controlled delivery of drugs.

Mechanical Behavior of Polystyrene-Grafted Natural Rubber/Natural Rubber Blend: Effect of Polystyrene Grafting Percentage

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.

Radiation-induced grafting of acrylic acid onto polypropylene film and its biodegradability

Abstract Polypropylene based commodity polyolefins are widely used in packaging, manufacturing, electrical, pharmaceutical and other applications. The aim of the present work is to study the effect of grafting of acrylic acid on the biodegradability of acrylic acid grafted polypropylene. The effect of different conditions showed that grafting percentage increased with increase in monomer concentration, radiation dose and inhibitor concentration but decreased with increase in radiation dose rate. The maximum grafting of 159.4% could be achieved at optimum conditions. The structure of grafted polypropylene films at different degree of grafting was characterized by EDS, FTIR, TGA, DSC, SEM and XRD. EDS studies showed that the increase in acrylic acid grafting percentage increased the hydrophilicity of the grafted films. FTIR studies indicated the presence of acrylic acid on the surface of polypropylene film. TGA studies revealed that thermal stability decreased with increase in grafting percentage. DSC studies showed that melting temperature and crystallinity of the grafted polypropylene films lower than polypropylene film. SEM studies indicated that increase in acrylic acid grafting percentage increased the wrinkles in the grafted films. The maximum biodegradability could be achieved to 6.85% for 90.5% grafting. This suggested that microorganisms present in the compost could biodegrade acrylic acid grafted polypropylene.

Modified tamarind kernel polysaccharide: A novel matrix for control release of aspirin

pH dependent hydrogels of modified tamarind kernel polysaccharide (TKP) were synthesized by grafting with polyacrylamide chains on TKP backbone in presence of microwave irradiation and initiator. The present study is carried out to design oral controlled drug delivery systems for aspirin using synthesized hydrogels as carrier in form of tablets. TKP-g-PAM based hydrogels show significant enhancement for control release of aspirin. Release behavior of aspirin has been evaluated using USP type I apparatus in 900mL of buffer solutions (pH 1.2, 6.8, 7.4), maintained at 37°C at 100rpm. It is observed that with increase in percentage of grafting (% G), swelling of matrices increases whereas erosion and rate of drug release decrease. The effect of % G onto t50 value (time taken for release of 50% drug) has also been discussed. The release characteristics from the matrices under study show non-Fickian diffusion mechanism, suggesting the controlled release of aspirin.

Graft copolymerization of methyl methacrylate onto bamboo cellulose under microwave irradiation

Grafting of methyl methacrylate (MMA) onto bamboo cellulose using ceric ammonium nitrate (CAN) as an initiator was carried out under microwave irradiation. The graft copolymers were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM). The effects of varying the microwave power, exposure time and concentration of initiator of graft polymerization were studied by determining the grafting parameters, such as grafting percentage and grafting efficiency. The experimental results showed that the optimal conditions for grafting were: [CAN] = 0.004 mol/L, which was acidified with 0.1 mol/L nitric acid; exposure time, 9 min; and the microwave power, 160 W. Moreover, the moisture absorption ability of the graft copolymers decreased significantly with the increase in grafting percentage.

Synthesis and characterization of a novel cationic chitosan-based flocculant with a high water-solubility for pulp mill wastewater treatment

In this work, pulp mill wastewater was treated using a novel copolymer flocculant with a high water-solubility, which was synthesized through grafting (2-methacryloyloxyethyl) trimethyl ammonium chloride (DMC) onto chitosan initiated by potassium persulphate. The experimental results demonstrate that the two main problems associated with the utilization of chitosan as a flocculant, i.e., low molecular weight and low water-solubility, were concurrently sorted out. The physicochemical properties of this flocculant were characterized with Fourier-transform infrared spectroscopy, 1H nuclear magnetic resonance spectroscopy, X-ray powder diffraction and field emission scanning electron microscopy. Reaction parameters influencing the grafting percentage, such as temperature, reaction time, initiator concentration and monomer concentration, were optimized using an orthogonal array design matrix. With an increase in grafting percentage, the water-solubility of the flocculant was improved, and it became thoroughly soluble in water when the grafting percentage reached 236.4% or higher. Its application for the treatment of pulp mill wastewater indicates that it had an excellent flocculation capacity and that its flocculation efficiency was much better than that of polyacrylamide. The optimal conditions for the flocculation treatment of pulp mill wastewater were also obtained.

Modification of Muga Silk by Methyl-Methacrylate. II

Abstract The physical properties of Methyl Methacrylate grafted Muga silk fiber (9.05 to 25.5% graft) were studied using standard methods. Properties of textile interest such as thermal insulating capacity, tensile properties like breaking load, tenacity, tensile strength, youngϵs modulus, and electrical properties such as electrical resistance were found to decrease with an increase in percentage of grafting. Possible explanations for such changes in properties are advanced and suitable end uses for the grafted fiber identified.

Structure and physical properties of grafted jute fiber

AbstractJute fiber was grafted by acrylonitrile and methylmethacrylate monomers in raw and bleached condition. It was also noted that optimum grafting takes place after about 4 h of grafting. It was also noted that in bleached jute fiber, the grafting percentage is higher at all stages of grafting but the tenacity value at the highest add‐on is practically the same as that of raw fiber with much less add‐on. The crystalline orientation of the grafted jute fiber was correlated with the fiber tenacity. The moisture regain (%) of the fiber after grafting showed a decreasing trend with an increase in grafting percentage. No structural change of the fiber occurred due to grafting. © 1995 John Wiley & Sons, Inc.

Modification of Tussah Silk by Methyl Methacrylate. Part II

Abstract The physical properties of methyl methacrylate grafted tussah silk fiber (9.6 to 36.9% graft) were studied using standard methods. Properties of textile interest such a8 thermal conductivity and shrinkage; tensile properties such a8 breaking load, tenacity, tensile strength, and Young' s modulus; and electrical properties such as electrical resistance were found to decrease with an increase in percentage of grafting. Possible explanations for such changes in properties are advanced and suitable end uses for the grafted fiber identified.