[en] Published in summary form only

[en] Positron lifetime measurements for some selected vinyl polymers have been performed. Samples have been made of : polyvinyl chloride, polyvinyl alcohol, polymethyl methacrylate, polystyrene and polyvinyl acetate. A conventional slow-fast coincidence lifetime spectrometer with plastic scintillators have been used for lifetime measurements. Mean free volumes radii have been calculated from the positron lifetime data. (author). 12 refs, 1 tab

[en] Preparation of two-layer hydrogel composed of polyvinyl alcohol (PVA), kappa carrageenan (KC) and carboxy methyl chitosan (CMS) laminated on polyvinyl pyrrolidone (PVP) and KC was conducted by gamma irradiation for the purpose of using as hydrogel wound dresser. The top part which designed to put to contact with the wounds would be soft hydrogel with anti-microbial activity from PVA and CMS respectively. The bottom part would serve asmain body of hydrogel, harder and absorb more wound exudate. KC was used for both layers as it could hold up more quantity of other polymers than that of agar and pregel was formed easily. The results showed that a proper constituent of the top part composed of 8% PVA 2.6% KC and 0.4% CMS. At radiation dose of 24 kGy, gel content was 9.4% with gel strength of 145 g/cm² and 250% swelling. The bottom part hydrogel composed of 7% PVP and 3% KC. At radiation dose of 24 kGy, gel content was 36.7% with gel strength of 588 g/cm² and 476% swelling. The prepared hydrogels were thus soft. possessed the power to kill germ and hold up more wound exudate

[en] A heavy charged particle detector is proposed which, to increase the registration threshold, is fitted with a sensitive polyvinylidenfluoride element. To ensure the required discriminatory power of the detector, the polyvinylidenfluoride is co-polymerized with tetrafluorideethylene which may amount up to 70 mol.%. The detector can be used for the threshold registration of accelerated multiply charged ions

No abstract available

[en] Tri-iso-amyl phosphate is an alternate solvent, proposed in literature as an alternate to the PUREX/UREX solvent tri-n-butyl phosphate for better physical properties. Its PVT properties and accurate expression for estimation of its vapour pressure are not available in the literature. Recently PVT properties of TiAP were estimated by authors and its vapour pressure was measured in a ASTM certified vapor pressure measurement system at temperatures ranging from 273.15 to 373.15 K. In this paper, results of these studies are presented. (author)

No abstract available

No abstract available

[en] Thermo-oxidative stability of poly (vinyl acetate) has been examined by measurement of loss in weight on heating in air. Weighted amounts of poly (vinyl acetate) placed in silica crucible were heated at four temperatures i.e. 125, 150, 175 and 200 deg. C for five hours in a ventilated furnace to an average atmosphere and weight losses were determined at various time intervals. These data were plotted as (a) percent volatilization in 5 hours versus temperature (b) as rate of volatilization versus percent volatilized. It has been found that above 125 deg. C the reaction proceeds rapidly, reaches a maxima then falls Activation energy based on rate of evaporation is found to be 12.98 Kcal/Mole. Further, work is in progress to enhance the thermal stability of poly (vinyl acetate). (author)

[en] In this paper, the effect of wheat straw (WS) pretreatments and glue formulations on mechanical (i.e. Compressive Strength (CS) and Impact Strength (IS)) and water resistance properties (i.e. Thickness Swelling (TS) and water absorption (WA)) of particle board have been investigated and the results have been compared with conventional wooden particleboard. Wheat straw was treated with steam available at 110 degree C and 20 psig, for the retention time of 5, 10 and 15 min. The solution of 10% HCl was also used for removing the lignin. Particleboard was prepared by bonding treated WS with four types of glue recipes of synthetic and natural binders like urea formaldehyde (UF), polyvinyl acetate (PVA), corn flour (CF) and wheat flour (WF). The particle board was formed at the hydraulic pressure and temperature of 2800 psig and 80 degree C respectively. It was observed that WS particleboard has low mechanical strength and high water resistance in comparison with conventional board. The particle board prepared with HCl cured wheat straw and glue having high urea formaldehyde and corn flour has higher CS and IS as well as low TS and WA. It may be concluded that wheat straw is a good substitute of wood for particle board while using HCl as a modifying chemical and strong binders like urea formaldehyde and corn flour. (author)