VOLUME 30, NO4, AUG 2008

The Effects of Plasticizer and Filler on the Curing Characteristic and Mechanical Properties of (SBR) Styrene Butadiene Rubber and (CR) Chloroprene Rubber Blends

Curing characteristics and mechanical properties of styrene butadiene rubber and chloroprene rubber blends have been studied. Carbon black loading in the range of 50-70 phr and plasticizer in the range of 7.5-12 phr was used. Minimum torque (ML), maximum torque (MH), cure time (Tc 90) and hardness was found to increase, while reduction in scorch time was observed by increasing the carbon black loading in the rubber matrix. Increasing the carbon black quantity in the rubber blends resulted in an enhancement of the tensile strength and tear strength up to 60 phr and then gradually decreased as the filler quantity was increased. The curing characteristics indicate that the rubber filler interaction increases the cure time with increasing filler loading. Tensile strength, tear strength and hardness were found to increases with the increasing plasticizer concentration up to 9 phr in the rubber blends. This property gradually decreases as the plasticizer concentration is increases up to 12 phr while elongation at break increases.read more

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TAHZEEB AKHTAR ,MAHMOOD IQBAL ,KHALID MAHMOOD ,ZIA ULHAQ FAROOQI ,

Thermoluminescence Method for Detection of Irradiated Black Pepper

Thermoluminescence (TL) method was investigated for detection of radiation treatment of black pepper (Piper nigrum), irradiated to gamma ray doses of 1.0 kGy and 5.0 kGy. The TL response of the minerals isolated from irradiated samples was much higher as compared to that of un-irradiated control samples. For the normalisation of results the separated minerals were re-irradiated to a normalisation dose of 1.0 kGy and TL glow curve recorded a second time. By comparing the glow curves of irradiated and unirradiated samples, it was possible to separate the irradiated samples from unirradiated ones. For laboratories having re-irradiation facilities, more accurate detection was possible by finding the ratio of the areas of first and second (re-irradiated) glow curves (TL1/TL2), which was confirmed by comparing the shapes of the glow curves of irradiated and un-irradiated samples.read more

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HASAN MAHMOOD KHAN ,IJAZ AHMAD BHATTI ,

Kinetics of Xanthate Sorption by Copper Sulphide (CuS)

A comprehensive kinetic study of the xanthate ions sorption on CuS was performed as a function of different experimental conditions of temperature and concentration. Adsorption kinetics experiments indicated that xanthate adsorption onto the CuS reached steady-state within approximately seven and ten minutes from the start of the experiment in case of high and lower concentration of xanthate anions respectively. Legregran’s first order equation was applied for the determination of the rate constant. Temperature had a positive effect on kinetics of the process and from the temperature dependence of the rate constant, energy of activation was calculated.read more

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SYED MUSTAFA ,ABDUL NAEEM ,DILHARA BEGUM ,SYED TASLEEM ,SULTANA QAMAR ,HAMID ALI ,

Heavy Metals Status of Industrial Effluents and Its Impacts on Human Life

Wastewater samples were collected from Hayatabad Industrial Estate, Peshawar and investigated for physical and chemical parameters. pH was in the range of 6.2 to 7.6, magnesium was 0.456-10.523mg/L, Copper was 1.035 to 10.230 mg/L, lead was 1.023-6.52 mg/L, manganese was 0.231- 9.852 mg/L, zinc was 0.231-12.34 mg/L, cadmium was 0.120-8.523 mg/L, cobalt was 0.214 – 4.562mg/L, silicon 0.321 – 14.52 mg/L, nickel was 0.231-12.3 mg/L, iron was 0.231-11.23 mg/L, and chromium was 0.123-6.321 mg/L. The values were compared with the standards of NEQS and it was found that some of the parameters show deviations due to the direct disposal of effluents into the environment and may affect life when they enter the water bodies. Therefore the effluents must be treated before they enter the environment.read more

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ILYAS AHMAD ,MIAN SAID WAHID ,MUHAMMAD HUSSAIN ,SULTAN ALAM ,FAZLULLAH KHAN BANGASH ,

Study of the Parameters Affecting the Viscosity of Chitosan Solutions

The temperature and storage time dependence of the viscosity of chitosan in a number of solvents (formic, acetic and propionic acids solutions) was determined. The temperature effect was studied over a temperature range of 20 ºC to 50 ºC while the storage time effect was examined at room temperature for a duration ranging between one to four days. The effect of chain length of the solvents on the viscosity of chitosan solutions was also investigated. Remarkable change in the viscosity of chitosan solutions was observed by varying the temperature, storage time and chain length of the solvents thus concluding that in the suitable design of experimental conditions these parameters play a vital role.read more

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ABDUL HAMID YAHYA ,ESAM AEL HEFIAN ,RASHID ATTA KHAN ,

Characterization of a Single Sample of Polymer by Dynamic Light-Scattering Technique

This article describes the characterization of a single sample of polystyrene in toluene using laser light-scattering (LLS) technique.  In dynamic LLS the Laplace inversion of precisely measured intensity-intensity time correlation function lead us first to an estimate of the characteristic line-width distribution G (G) and then to the translational diffusion coefficient distribution G (D).  By using previously established calibration of D = (3.64 x 10-4) M-0.577, we were able to convert G (D) into a differential weight distribution fw (M) for the single sample of polystyrene. The weight-average molecular weights calculated from fw (M) are comparable to that obtained directly from static LLS.  Our results showed that using single polystyrene sample instead of a set of narrowly distributed samples provided not only similar final results, but also a more practical method for polystyrene characterization.read more

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WILAYAT AHMED KHAN ,IMTIAZ AHMED ,MUHAMMAD SIDDIQ ,KHALID MAHMOOD ,BAKHTIAR MOHAMMAD ,

A Study of Electroless Nickel-Boron Coating Process

An electroless nickel-boron coating method has been developed that attempts to overcome the problems that are generally associated with the process of applying coatings. The problems include irregular film deposits and brittleness. The method is versatile and is applied for coatings on a number of substrates, including brass, copper, mild steel and stainless steel AISI 316L. Growth rates of 14 to 22 microns per hour are possible. The deposited coating thickness varied with the amount of complexing agent added to the solution, sodium borohydride concentration and to the bath temperature. When the deposits are annealed at 400 °C, transformations of amorphous nickel-boron deposits to crystalline nickel and Ni3B are obtained. The boron content in coated film varied from 1.26 % to 4.15 %.read more

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TARIQ DURRANI ,

Influential Role of Al2O3 and B2O3 on Selenium Ruby Glass

This paper represents the results of investigations on the melting of selenium ruby glass, particularly on the effect of Al2O3 and B2O3 on ruby colour. A glass of base composition (wt. %) SiO2 65.0, Na2O 15.5, K2O 5.3, ZnO 12.0, B2O3 1.0, CdS 0.6, Se 0.6 has been chosen for these studies. In this study Al2O3 and B2O3 are systematically substituted for Na2O in small amounts from 0.5 to 3.0 %. Effects of these substitutions on melting, refining, colour, striking temperature etc. have been recorded. Transmittance of some representative samples has been determined. Glasses containing Al2O3 1.5 to 2.5 and  B2O3  2 to 3.0 % have been found suitable for the development of red signal glass. Pilot plant meltings also gave satisfactory results.read more

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MUHAMMAD AFZAL KHAN ,AHMAD DIN ,MUHAMMAD PERVEZ IQBAL QAZI ,MUHAMMAD SAADAT KHAN ,MUHAMMAD ASLAM CHAUDRY ,

Adsorptive Interaction Studies of Aqueous Carboxylic Acids with Smectites, Kaolin and their Li-Exchanged Forms

Commercial smectites (montmorillonite, hectorite and bentonite) and kaolin clays were purified by fractionated sedimentation with fraction < 2 µm particle size and their Li-exchanged forms were prepared by cation exchange method and characterized by XRD and SEM techniques. The XRD Patterns confirmed the purity and crystalline nature and SEM images indicated the particle sizes and morphologies of the materials investigated. Gels of smectites are formed when concentrations are greater than ~ 2 % by weight in deionized water.  The effects of adsorptive interactions of aqueous carboxylic acids (HCOOH, CH3COOH and CH3CH2COOH) 20 % (V/V, 10mL) were examined refractometrically using 0.05g of each clay sample in 14mL vials at room temperature. The experimental results proved that hectorite i.e., trioctahedral magnesium smectite showed preferential adsorption of water from aqueous phase of carboxylic acids. Smectites (0.5 %) expanded and changed into jelly-like forms and kaolin formed a swollen paste in the aqueous carboxylic acids in vials. The sizes of the cylindrical shaped jells of smectites formed depend on the layer charge density, location of charge, size of carboxylic acid and nature of the interlayer cation and its hydration properties, were in the following order.Li-montmorillonite > Na, Ca-montmorillonite > Na-bentonite > Li-bentonite > Na-hectorite » Li-hectorite.It was also observed that the cylindrical shaped jells of the clays formed were largest in the aqueous propionic acid. The 0.5 % by weight of commercial clays formed slurries while pure clays changed to suspensions in deionized water in vials under similar conditions. The interactions of the water and carboxylic acids with the interlayer cations and the exposed smectite clay surface are responsible for the swelling due to the expansions of the interlayers from its dry state.read more

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SHER AKBAR ,KRISTA S WALTON ,MEGAN PUKALA ,

Experimental Study of Calcination-Carbonation Process for the Production of Precipitated Calcium Carbonate

The limestone of Swabi district was used to produce precipitated calcium carbonate. The optimum calcination temperature and time was found to be 10000C-11000C and 3 hours to 4 hours respectively. The results show that the stirrer speed of 130 rpm is the most suitable, as higher speed causes attrition of precipitates. The required particle size of precipitates of calcium carbonate can be achieved by choosing the right concentration of calcium hydroxide suspension. The impurities provide additional nucleus for precipitate formation affecting brightness and specific gravity of the product.read more

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SAMEER AHMAD ,ANWAR SAEED AHMED ,MUHAMMAD TARIQ SAEED ,SHER KHAN AFFRIDI ,MUSTANSIR BILLAH BHATTY ,