ABSTRACT:The polymer systems of vinyl latex, epoxy latex/resin, and phenol formaldehyde were used to modify sand-cement mortar at room temperature. The compressive strength increased with an increase of the latex/resin concentration, with the addition of CaCl 2 or CaCO 3 , and with the addition of superplasticizer. Tensile and flexural strengths also increased with polymer incorporation. The porosity of the modified mortar decreased with the addition of resin. The percentage of water absorption and acid solubility were found to decrease for the latex/resin modified samples.

SYNOPSISSince it has been reported in the literature that polymer-grafted wool fibers have better acid and alkali resistances and dye uptake, the present study was carried out using KBr03 and substrates such as Fe (II), Co (11) , cysteine, cystine, tyrosine, and urea for graft copolymerization of methyl methacrylate ( MMA) onto wool. Acid and alkali resistances, dye uptake, and dry tensile strength of the resulting graft copolymers were studied.

Kinetics of polymerization of acrylonitrile by the redox system V5+–lactic acid in sulfuric acid at 20–35°C was studied. Oxidation of lactic acid by V5+ in the absence of monomer was also carried out under identical conditions. The rates of polymerization, V5+ disappearance and the chainlengths of polyacrylonitrile were measured. From the results it is concluded that the polymerization reaction is initiated by an organic free radical arising from the V5+–lactic acid reaction with termination by V5+ ions. Mutual termination of active polymer radicals does not appear to operate under the conditions studied. The various rate parameters were evaluated.

The effects of the concentrations of monomer, cyclohexanol, V5+, H,SO,, HSO,, SO:-, Cland ionic strength a t 40 to 6OoC on the rate of V5f disappearance and the rate of polymerisation of acrylonitrile were studied. From the experimental results, it was concluded that the organic free radicals formed during the decomposition of the V5f-cyclohexanol complex, initiated polymerisation and that the polymer radicals were terminated by V5+ ion. An appropriate kinetic scheme was proposed and the various rate and energy parameters were evaluated. ZUSAMMENFASSUNG:Die Abhangigkeit der Polymerisationsgeschwindigkeit des Acrylnitrils und der Geschwindigkeit des Verschwindens des V5+ von den Konzentrationen von Monomerem, Cyclohexanol, V5+, H$O, HSO,, SO:-, C1-sowie von der Ionenstiirke wurde untersucht, und zwar bei Temperaturen zwischen 40 und 6OoC. Aus den experimentellen Ergebnissen wird abgeleitet, daB die Polymerisation durch Radikale gestartet wird, die durch Zerfall eines V5+-Cyclohexanol-Komplexes entstehen, und daB die Makroradikale durch das V5+-Ion desaktiviert werden. Die verschiedenen Geschwindigkeits-und Energieparameter w r d e n bestimmt, und es wird ein kinetisches Schema vorgeschlagen.

SYNOPSISThe thermal properties of wool fibers can be improved by graft copolymerization with vinyl monomers. Using TGA, DTG, and DSC techniques, the thermal behavior of methyl methacrylate grafted wool fibers was studied. Graft copolymerization was carried out using KBr03 and substrates such as Fe( 11), Co( 11), cysteine, cystine, tyrosine, and urea. Of all the systems studied the grafted fibers which involve Fe( II), Co (II), and cystine gave improvement in the thermal stability.