Iranian Journal of Polymer Science and Technology
Year:2004 | Volume:16 | Issue:6 (ISSUE NO. 68)|Papers Count:6

EPDM Rubber is one of the unsaturated general purpose elastomers having low density and high filler loading ability. Silica is one of the reinforcing fillers used in EPDM rubber compound. In this research work, the effect of three different coupling agents on silica filled EPDM compound were studied. The results showed that coupling agent affected on curing behavior and filler polymer interaction with physical and mechanical properties improvement.

It is essential to control polymerization parameters in order to reach a specific polymer. A fuzzy controller is proposed to control temperature using reactor and jacket deviations. However, uncertainty exists on a jacket temperature, due to noise and disturbance effects. Fuzzy numbers are applied to model this uncertainty. Consequently, a fuzzy trajectory is derived for jacket temperature. Finally, a pseudo-Sugeno fuzzy controller is designed for temperature tracking. The results show the good performance of this controller for control of solution polymerization of methyl methacrylate.

Polyurethane thickeners are one of the important members in associative thickeners. These materials are divided in two groups of S-G HEUR and Uni-HEUR depending on their synthetic procedure and molecular weight distribution. In this work, three S-G HEURs (step growth hydrophobically modified ethoxylate urethane) were synthesized through a two-step polymerization. In the first step, prepolymers were produced via reaction of poly (ethylene glycol) with H12 MDI. Then, the synthesis of HEURs was finished by substituting of cetyl alcohol in the prepolynmer. Molecular weights of thickener models were determined by GPC. Associative bahavior was studied by Ubbelhode viscometery. Also, a cone and plate rheometer was used to investigated the obtained results from Ubbelhode viscometery. The results showed that some associations are present even at very low concentration. Also, the sample with shorter hydrophilic size showed stronger association behavior.

Sheet molding compound (SMC) is among the most common materials in the manufacture of composite parts. The main characteristic of the base resin used in the manufacture of these materials is its capability of viscosity build-up to molding region. In this research, thickening behavior of an unsaturated polyester (UP) resin with three thickening agents, i.e., MgO, methyl diisocyanate (MDI) and MDI/MgO was investigated. The effect of thickener level, temperature and filler content was also studied. Mechanical properties of the molded SMCs were determined. Isocyanate-thickened SMC showed the highest flexibility, while MDI/MgO thickened SMC displayed the maximum flexural and tensile modulus. There was no much difference in impact strength of the SMCs thickened with various methods.

Preparation of maleic anhydride-grafted polypropylene (PP-g-MA) as compatibilizer and the preparation of the blends of polypropylene and polyethylene terephthalate by catalyzed reactive blending in a co-rotating twin screw extruder using para-toluene sulphonic acid as catalyst were investigated. IR spectroscopy and titration results confirmed the successful melt grafting. The effects of compatibilizer on rheological, thermal, and thermomechanical properties and the morphology of PP/PET blends were also studied. The percentage of PET in all blends was fixed at 20% and the compatibilizer content was changed 5-15%. Rheological studies showed that the viscosity of PP was decreased upon melt grafting. This is due to chain scission and decrease in molecular weight. The non-compatibilized and compatibilized blends rheologically behave very similar to PET (lower viscosity component). It means that the viscosity of blends decreased on the addition of the compatibilizer.The DSC results showed that melt grafting has a significant effect on increasing the PP crystallinity. Thermomechanical studies showed that by grafting MA on PP, the storage modulus was increased, whereas, the loss modulus decreased. The SEM micrographs showed that the inter-facial interactions significantly were improved by addition of small amounts of the compatibilizer. A sharp decrease in the size of minor phase inclusions was also observed. The interface was saturated with 10% compatibilizer. The compatibilizer was very successful in improving the properties of blends.