M. E. Haque

Radiation dose required for the vulcanization of natural rubber latex

The radiation dose required for the vulcanization of natural rubber latex was optimized. To enhance the crosslinking, several sensitizers were used. Among the sensitizers, n-butyl acrylate (n-BA) alone was found to be the best one. The effects of concentration of n-Ba, mixing and standing time of latex with n-BA on the tensile properties of latex film were investigated. 12 kGy radiation dose, 5 phr n-BA and 30–40 min of mixing time were found to be the optimum conditions for irradiation.

Characterization of Poly(Vinyl Alcohol) and Poly(Vinyl Pyrrolidone) Co-polymer Blend Hydrogel Prepared by Application of Gamma Radiation

Hydrogel is prepared from a poly(vinyl pyrrolidone) (PVP) and poly(vinyl alcohol) (PVA) blend solution by gamma radiation with a 60Co λ source at room temperature. Properties of the prepared hydrogel, such as gel fraction, gel strength swelling ratio, equilibrium water content, and water absorption in room temperature, were investigated. Blending hydrogel with PVP and PVA obviously increased the gel strength and decreased the swelling ratio of hydrogel. It was observed that the gel fraction increased while the swelling ratio and water content decreased with increased radiation dose, but gel strength increased up to a certain radiation dose and then decreased. The percentage of water absorption at room temperature increased with time but after a certain time it became steady and decreased with radiation dose.

Effect of Natural Antioxidant (Diospyros peregrina) on the Aging Properties of Radiation Vulcanized (γ-Radiation) Natural Rubber Latex Film

Natural rubber latex and various concentration of natural antioxidant were blended in different ratios and irradiated at various absorbed doses by gamma rays from Co-60 source at room temperature. The aqueous extraction of Diospyros peregrina was used as natural antioxidant. It was found that the addition of different concentration of natural antioxidant into natural rubber latex improve the aging property of the film. Decreasing in tensile strength of rubber film with 10 phr natural antioxidant and 15 kGy radiation dose after 24 hours aging at 100°C was 9.34% compared to 13.89% for film without natural antioxidant. The tensile strength, tear resistance and modulus at 500% elongation of the rubber film were found to be optimum at 15 kGy radiation dose and with 10 phr natural antioxidant. Elongation at break, permanent set and swelling ratio decreases with the increasing absorbed radiation dose as well as the concentration of the natural antioxidant.

Studies on the Relative Degradation and Interfacial Properties Between Jute/Polypropylene and Jute/Natural Rubber Composites:

Jute fabrics (hessian cloth) reinforced polypropylene (PP) matrix composites (30% fiber by weight) were fabricated by compression molding. Tensile strength (TS), tensile modulus (TM), and percentage elongation at break (Eb) of the composites were found to be 32 MPa, 740 MPa, and 16%, respectively. Then jute fabrics reinforced solid natural rubber (NR)-based composites (30% fiber by weight) were also fabricated and it was found that TS, TM, and Eb of the jute/NR composites were 14 MPa, 120 MPa, and 94%, respectively. The mechanical properties of jute/PP and jute/NR composites were compared. Six weeks of degradation of the composites were performed in aqueous medium and it was found that jute/NR composites lost much of its original strength and modulus compared to that of the jute/PP composites. Interfacial shear strength (IFSS) of the jute/PP and jute/NR systems was investigated by using the single fiber fragmentation tests. The IFSS of jute/PP and jute/NR systems appeared to be 2.16 and 0.89 MPa, respectively. Fracture side of the composites was also studied by scanning electron microscope and suggested better fiber matrix adhesion between jute fiber and PP.

Effect of Kappa-Carrageenan on the Properties of Poly (Vinyl Pyrrolidone) Hydrogel Prepared by the Application of Radiation

Poly (vinyl pyrrolidone) hydrogels with kappa-carrageenan (KC) were synthesized by γ-ray irradiation. The conditions of synthesis such as variation of total radiation doses and concentration of KC were determined. The properties of the prepared hydrogels, such as gel strength, gel fraction, swelling ratio, and water absorption were evaluated. Gel strength and gel fraction attain maximum up to a certain dose but swelling ratio and water absorption decrease with increased total doses. Gel strength, swelling ratio, and water absorption increase with an increase in the concentration of KC but the gel fraction reduces.

Synthesis of Hydrogel from Aqueous Solution of Poly(Vinyl Pyrrolidone) with Agar by Gamma-Rays Irradiation

Abstract: Hydrogels were prepared from an aqueous solution of poly(vinyl pyrrolidone) (PVP) by using γ-rays from a Co-60 source at room temperature. For this purpose, effects of radiation dose and concentration of polymers on the properties were investigated. The gel fraction, gel strength, and elongation at break attain maximum at the radiation dose of 20 kGy. But swelling ratio decreases with increased radiation dose. On the other hand, gel strength, gel fraction, and elongation at break increase with an increase in the concentration of PVP. Agar improves gel strength and elongation at break but reduces gel fraction and swelling ratio.

Study on the Properties of Blend Rubber Between Grafted Rubber Latex and Natural Rubber Latex by Gamma Radiation

Blend rubber films were prepared by mixing styrene grafted rubber latex and natural rubber latex (NRL) with varying proportions by gamma radiation from Co-60 source at room temperature. Tensile strength, modulus at 500% elongation, elongation at break, permanent set, and swelling ratio were measured. Tensile strength and modulus at 500% elongation attain maximum at 8 kGy radiation dose for blend rubber films. The increase in tensile strength is insignificant, but modulus increases from 5.61 to 7.46 MPa with increased proportion of grafted rubber latex from 40 to 70% in the blend at this radiation dose. Elongation at break, permanent set, and swelling ratio of blend rubber decreases with increase in radiation dose as well as proportion of grafted rubber.

Improvement of Physicochemical Properties of Rubber Blends Between Nonirradiated and Irradiated Rubber Latexes by Radiation Vulcanization

Abstract Nonirradiated natural rubber latex (NRL) and irradiated (12 kGy) rubber latex were blended in ratios of 100:0, 85:15, 65:35, 50:50, 35:65, 15:85, and 0:100 (v/v) to improve properties of the rubber latex. The blends were irradiated using different irradiation doses (0–20 kGy) in the presence of a radiation vulcanization accelerator (RVA), normal butyl acrylate (n-BA). The physicochemical properties of the nonirradiated latex, irradiated latex, and blend films were determined after leaching with distilled water. It was observed that the tensile strengths of the blend films increases with an increase in the content of the irradiated proportion and radiation doses. The composition of the blends and the doses of radiation were optimized. The maximum tensile strength (31.41 MPa) was found for the 50:50 composition of the blend with a 5 kGy radiation dose. The 100:0 blends, when irradiated, give the highest tensile strength (27.69 MPa) with 12 kGy but a 15:85 nonirradiated blend gives the tensile strength of 26.18 MPa.

Study on the Properties of Radiation Induced Acrylamide Grafted Natural Rubber Latex Film

Grafted rubber films were prepared by mixing various proportions of acrylamide with natural rubber latex (NRL) with varying proportions by gamma radiation from Co-60 source at room temperature. Tensile strength, tear strength, elongation at break, permanent set, and swelling ratio, gel content and degree of grafting were measured. Tensile strength, tear strength, gel content and degree of grafting were found increasing with absorbed dose, as well as the proportion of monomer concentration and the optimum dose was found 12 kGy from the results. Elongation at break, permanent set, and swelling ratio of grafted rubber decreases with increase in absorbed dose, as well as proportion of grafted rubber.

Dependence of Physicochemical Properties of Radiation Vulcanized Natural Rubber Latex Film on Maturation Time

The effect of latex maturation on the physicochemica1 properties of radiation vulcanized natural rubber latex films was studied. The properties were compared to those of the nonirradiated natural rubber latex films at the same condition. For this purpose, field and concentrated latices were used. Tensile strength, modulus, tear strength, gel content, and cross-link density for both the nonirradiated and irradiated latex films increase with the increased length of maturation time, and these properties possess maximum values at nine weeks maturation period, whereas the elongation at break decreases to a minimum at the same length of maturation time.