Iranian Journal of Polymer Science and Technology
Year:2002 | Volume:15 | Issue:1 (ISSUE NO.57)|Papers Count:6

The belt section in a low aspect ratio steel-belted radial tires is more important than compared with the other tires. In this study, we attempt to improve the adhesion between rubber compound and steel-cord.In the first step we have analyzed the belt section of reference tire (Brigestone tire) and then designed and modified some of the compounds. Therefore, an optimized compound has been obtained by varying the percenatge of ingredients. It is shown that the naphthenate cobalt has more effective role for improving the adhesion among the others.

Hydrophilicity at room temperature for vulcanized silicone rubber (RTV) was characterized prior and after addition of different ratios of poly (acrylic acid), PAAC, hydrogel. It was found that there is a direct linear relationship between equilibrium water content and the amount of hydrogel present in the matrix. Also a noticeable dicrease in contact angle was observed with increase in hydrogel content which confirms the hydrophilic character of the composite material. The degree of water uptake was found to have a direct and linear relationship with the hydrogel's degree of cross linking although this effect has not been very obvious. However, it may be assumed that the amount of hydrogel in the matrix is the determinant factor of hydrophilicity rather than that of cross linking agent in PAAC. Considering two different particle sizes for PAAC particles it is noticed that the equilibrium water uptake with particles less than 120m is higher than the particles sizes under 2S0 m Therefore, the particles sizes within these given ranges cannot be considered an important factor in equilibrium water uptake. But this characteristic effect of surface irregularities on blood compatibility is not ignorable. Finally, observation of unpredictable variations in contact angle values, and in particulars, surface tension. With respect to composite surfaces confirm the conjecture that interaction of the ionic PAAC hydrogel with aqueous medium, as manifested by surface tension in this study, was a function of hydrogel particle distribution in the matrix.

During the production and processing of textiles, determination of wettability is a matter of prime importance. Measurement of fibers weltability seems to be a straight forward process but it always faces in various ways. For this reason, several procedures have been proposed by different investigators. In the present work, the different methods of the measurements of wettability and liquid-fiber contact angle are reviewed and briefly discussed with emphasis on the problems involved with each method. Among these methods, determination of contact angle by weighing the water absorbed by a bundle of yarns, seems to be simple with higher practicality. This method is used for the measurement of contact angle between water and polyester fibers in yarn form. The contact angle is calculated from the weight of water absorbed at different time intervals, and the results are compared with those available in literature. It seems that due to the different approximations used and the changes in the surface structure of the fibers, it is not possible to assign a single contact angle for a given fiber - water system.

Polyaniline was synthesized chemically. The purified form of polyaniline was swollen with THF before dispersing in N-methyl pyrrolidone for film making. The thickness of the films were 80 and 100 micrometers. Polyaniline films were doped with hydrochloric acid at two different concentrations for varied periods of time. The doped films with areas of 1 cm2 were used as conducting plates, and papers were soaked with paraffin as dielectric of conducting polyaniline capacitor. In the present work design, construction of capacitor based on conducting polyaniline films has been investigated experimentally. The results of measurement and calculation of capacitance of the designed capacitor, assuming that diffusion of dopant in polyaniline is plate-like, arc reported. Stability under both atmospheric and vacuum conditions were investigated. Experimental results and theoretical studies show that by increasing the doping time, capacitance is increased. Also, the thinner insulating form of polyaniline film, the faster the two conducting fronts meet and the capacitor reaches a maximum. The value of this maximum in the present work was 42PF.

The outstanding properties of polymers are considered significant in polymer membranes with it many diverse uses. The membranes and specifically thin rubber sheets have made their ways in a vast area of important uses as in protective clothing, separation or liquids and chemical wastes or refining. Therefore, mass transfer of liquids in rubber sheets is considered important in adsorption. diffusion and particularly in separation processes in the study of natural rubber NBR, SBR and EPDM which arc mechanically considered suitable and are selected in the mass transfer studies of the aromatic solvent mixtures like benzene and 1.2- dichloro benzene. The solubility parameter(s), diffusion (D) and permeation (P) are measured using mass transfer methods. Calculations for evaporations at low pressure are used at different temperatures for thin elastomer sheets. The separation level for NBR membrane shows the highest efficiency while the separation for EPDM membranes in aromatic solvent is at its lowest level of efficiency

In chitin extraction from the shrimp's shell the influence of extraction parameters (reaction time length, temperature and concentration of reagents) was studied.In this study chitin was extracted from shrimp's shell of Persian Gulf, using different methods. The process parameters were optimized to chitin with 6.8% nitrogen content and the viscosity average molecular weight (Mv) of 3.22´106 and ash content of 0.34 Chitin extraction yield from shrimp's shell was 25-30%. Degree of deacetylation (DD) and molecular weight are structural parameters which influence industrial uses such as medical application.Deacetylation or chitin was carried out by optimized reaction parameters (reaction time length. Temperature, concentration of alkaline reagent and sea sources of chitin). Experimental deacetylation conditions were studied and physicochemical characteristics of the obtained chitosan were compared.This work suggests that at these experimental deacetylation conditions (T=90, t=5h, freshness of chitin and 50% NAOH) it is possible to reach molecular weight as high as 3.57´105 and degree of deacetylation 86%.