M. U. Ahmad
Jahangirnagar University
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Featured researches published by M. U. Ahmad.
Radiation Physics and Chemistry | 1996
M. E. Haque; N. C. Dafader; F. Akhtar; M. U. Ahmad
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.
Polymer-plastics Technology and Engineering | 2012
M. A. Haque; M. U. Ahmad; M. A. Khan; S. M. A. Raihan; N. C. Dafader
Natural Rubber Latex (NRL) and Polyvinyl pyrolidone (PVP) blends with different PVP concentrations were prepared and rheological properties of NRL/PVP blends have been investigated at different speed range. Significant changes of behaviors are found with increased PVP in blends. Yield stress increases with increased PVP in blends. The increasing trend of stress increases with PVP content in blend. Shear stress and yield stress increase with increased speed range. Change of nature of rheogram of NRL with PVP indicates the interaction between NRL and PVP. Increasing speed range, the decreasing trend of viscosity indicates the orderliness of molecular segments in blends.
Polymer-plastics Technology and Engineering | 2006
N. C. Dafader; M. E. Haque; F. Akhtar; M. U. Ahmad
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.
Polymer-plastics Technology and Engineering | 2005
M. A. Haque; M. U. Ahmad; F. Akhtar; N. C. Dafader; M. E. Haque
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.
Polymer-plastics Technology and Engineering | 2003
N. C. Dafader; M. E. Haque; Y. N. Jolly; F. Akhtar; M. U. Ahmad
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.
Radiation Physics and Chemistry | 1995
M. E. Haque; N. C. Dafader; F. Akhtar; M. U. Ahmad
Abstract The mechanical properties of radiation vulcanized natural rubber latex of various clones were evaluated and compared. The dependences of the properties of latex film on the green strenght and on the type of clone were discussed. The green strength of the latex film varies from one clone to another and the tensile strenght of the film depends on the green strength to a considerable extent. The effects of radiation dose and leaching on the properties of latex film were reported.
Journal of Macromolecular Science, Part A | 1995
M. E. Haque; F. Akhtar; N. C. Dafader; F. R. Al-Siddique; A. R. Sen; M. U. Ahmad
Abstract Natural rubber field latex has been concentrated by a laboratory scale centrifuge machine to attain ISO requirements. The optimum conditions for various parameters e.g., frequency of the power source, flow rate of the latex into the machine, ring dam diameter of the separator, total solid content of the field latex, concentration of the preservative in the latex, have been established. The characteristics of latex concentrate were compared to those as required by ISO 2004: 1974.
Polymer-plastics Technology and Engineering | 2007
M. A. Haque; M. U. Ahmad; F. Akhtar; N. C. Dafader; M. E. Haque
Variable compositions of natural rubber latex (NRL) and polyvinyl alcohol (PVA) have been blended. The contents of PVA in the blends were varied from 0.5 phr to 3.0 phr and the total solids contents of NRL was fixed to 50%. The blends were irradiated at different irradiation doses (0–20 kGy) in the presence of normal butylacrylate (n-BA). The permanent set; swelling ratio and elongation at break point of the blended films at all compositions decrease with the increase of radiation doses whereas increase is observed in cross-linking density, gel content, tensile strength and modulus. Sharp changes of all the properties were observed between 3–5 kGy radiation doses. On the other hand, at higher radiation doses, ≥ 5 kGy, the permanent set, swelling ratio, gel content did not show any appreciable change whereas cross-linking density, tensile strength, modulus and elongation at break point are changed. The maximum cross-linking density of blend is observed with 2.0 phr PVA at 12 kGy radiation. The highest value of modulus and tensile strength of the same blend are found at 10 kGy and 5 kGy respectively. Blends with 2.0 phr PVA for all compositions proved to be optimum for improving varies properties at 5–12 kGy radiation doses.
Polymer-plastics Technology and Engineering | 2010
M. A. Haque; M. U. Ahmad; M. A. Khan; S. M. A. Raihan; N. C. Dafader
NR and Polyethylene (PE) were blended at different compositions of PE, like 00, 35, 50, 65, 85 and 100% by extrusion method and then the blend films were made by hot press. The blends, NR and PE films were irradiated and their mechanical properties were investigated before and after leaching. Blend compositions were optimized and found that the 50–65% PE blends give the best quality. It is also found that 5–8 kGy radiation doses are optimal for improved properties of blends. Leaching enhances mechanical properties and lower radiation doses give more enhanced mechanical properties compared to unleached one.
Polymer-plastics Technology and Engineering | 1999
N. C. Dafader; Y. N. Jolly; M. E. Haque; F. Akhtar; M. U. Ahmad
The effect of coagulants on the preparation of dipped film with good physical properties was studied. In order to optimize various parameters like coagulant concentration, latex concentration, and former dipping time in latex and coagulant, the effect of coagulant on the physical properties of radiation vulcanized natural rubber latex film was evaluated. Calcium nitrate, calcium chloride, and ammonium nitrate were used as the coagulant by dissolving either in water or ethanol. Calcium nitrate solution was found to be the best one among the coagulants used.