Iranian Journal of Polymer Science and Technology
Year:2003 | Volume:15 | Issue:6 (ISSUE NO.62)|Papers Count:5

Conductive membranes show many benefits including fouling reduction for feeds containing ionic species. These membranes may be prepared either by conductive polymers or coating of the surfaces of non-conductive membranes with conductive polymer. In this research, the commercial microfiltration GVHP membrane manufactured from PVDF was coated with polypyrrole using two different techniques. The conductivity of the prepared membranes was measured. In this paper, effects of various factors including concentration of the solutions, oxidizing agents, time for leaving the support in the solutions, support type and temperature on membrane conductivity were investigated.

In this research the effects of formulation and the amount of triallylcyanorate (TAC) as coupling agent on peroxide vulcanization and mechanical properties of the participated amorphous silica filled EPDM elastomer are investigated. The results of curing process and measuring the mechanical properties (hardness, modulus, tensile strength, elongation-at-break, abrasion, resilience and Mooney viscosity) of compounds showed that silica accounts for mechanical properties improvement and TAC increases Mooney scorch time and it reduces optimum curing time, therefore it prevents compound scorching. In addition, results showed that TAC improved rubber-filler interaction and apparent crosslink density, which reflected on mechanical properties under study.

Suspension polymerization of styrene-acrylonitrile at 75oCunder atmospheric pressure was studied. To have copolymer with azeotropic composition, it was found that 30%AN in feed is needed. Different grades based on different average molecular weights were synthesized and relative procedures discussed. Mixed initiators of lauryl peroxide and benzoylperoxide were used in presence of n-dodecylmercaptane (n-ddm) as chain transfer agent. It was found that for isothermal copolymerization the optimum concentration of n-ddm is 0.1%.

The effect of two non-halogenic flame retarders, alumina trihydrate and antimony trioxide, on the flammability, mechanical and thermal properties of silane crosslinked polyethylene has been investigated. It was found that with addition of flame retarders the limiting oxygen index (LOI) was increased. With crosslinking, LOI was increased further more. Mechanical properties decreased with increasing the amount of flame retarders. Crosslinking improved the mechanical properties of polyethylene with flame retarders

Cryoaccumulator gels can retain cold temperature for long periods of time. These gels are used in medicine and transporting of medico-biological objects in cold condition. In this paper, two types of gels, the so-called soft gel and hard gel, have been formulated. Polyacrylamide, which was synthesized by precipitation polymerization in acetone, has been used as a gel in formulation of these cold packs. To evaluate the cold duration in the formulated gels, temperature changes of these gels have been measured versus time. Performed tests showed that cold duration in hard gels is longer than in soft gels, on precise term, average life of a soft gel is about 3h and for a hard gel it is about 10h. Also, the polyacrylamide crosslinking density affects the cold duration in soft gels. It has been evaluated and observed that with changing this parameter we can substantially extend the cold life of these gels.