Iranian Journal of Polymer Science and Technology
Year:2005 | Volume:17 | Issue:6 (ISSUE NO. 74)|Papers Count:6

In this study the melt blending of a thermoplastic rigid polymer (POM) with a chemical resistant elastomer (NBR) is performed. The blending is done in a counter -rotating twin screw extruder. The optimized setting of the important process parameters like temperature, residence time, screw rotation and the retarder quantity was calculated from the results of our previous work. Also a sulfur base curing procedure was devised for dynamic vulcanization of the blend. It was shown that employing either SAN or SBS as a third component compatibilizer would improve the morphology of the blend. In this regard by fixing the process condition the mechanical properties of the two-component POM/NBR blend was compared with that of a compatibilized one (with either SAN or SBS), as well as the samples that where dynamically cured. The results showed some improvements in the mechanical properties by both compatibilization and curing. It was also shown that for samples with NBR as a major component the curing is a dominant factor of the final products quality. It was observed that SAN acts as a better compatibilizing agent than SBS for our blending system.

Variations in the physico-mechanical properties of PET carbonated beverage bottles during shelf-life have been studied at different temperatures. Several carbonated beverage bottles were kept at two temperatures (10 and 20°C) for 4.5 months. During two weeks physical properties such as pH, density and CO2 gas permeation of bottles as well as the mechanical properties were determined at two temperatures. The results show that pH and density of PET bottles have not changed during shelf-life at two different temperatures, but there is a reduction in pressure of CO2 at 20°C and after 4 months, which it reached half its level. On the other hand, PET bottles show a reduction in mechanical properties after 10 weeks residence time due to the interaction between the beverage and the bottles.

Honeycomb sandwich panels are increasingly being used for various engineering applications due to their low weight and excellent mechanical properties. Aluminium and reinforced plastic cores are used for general purpose applications whilst Nomex cores are mainly used in aerospace industry. More recently thermoplastic cores, made from polypropylene and polycarbonate, have also become available. The aim of this project is to develop design methods and manufacturing techniques for polypropylene core honeycomb sandwich panels. Honeycomb sandwich panels were fabricated in-house and subjected to physical and mechanical tests. Test results have indicated that these honeycombs when subjected to compressive loads exhibit relatively high compressive strengths. Experimental results also showed that the compressive strength of panels is independent of core thickness. However, flexural strength of honeycomb sandwich panels increases with an increase in core thickness.

The feasibility study for production of PHAs by activated sludge has been carried out. The laboratory experiment was accomplished in the following two stages: Firstly, activated sludge with high potential of PHA production was acclimatized in PHA accumulating bacteria enrichment reactor (PABER). In this reactor wastewater was treated under 10h hydraulic retention time and qc of 5 day. Secondly, the activated sludge acclimatized in the PABER was transferred into "PHA production reactor". In this reactor the wastewater with high concentration of volatile fatty acid (VFA) is fed as carbon sources for PHA production. As a result, it was possible to produce PHA from activated sludge. Activated sludge acclimatized in the anaerobic-aerobic process accumulated PHA as much as 17% of sludge dried weight. The composition of PHA was investigated to be 14% of 3HB and 3% of 3HV by weight. In this system 0.325g PHA was produced per 1g of carbon consumed.

Organic-inorganic hybrid coatings prepared by sol-gel process due to having organic-inorganic networks in their structure have a set of mechanical and chemical properties and as a result they attract a lot of interest. These coatings were prepared by a two-step process: hydrolysis and condensation reaction of silane compounds, that is, 3-glycidoxy propyl trimethoxy silane (GPTMS) and tetramethoxysilane (TMOS) in the presence of acid catalyst and as a bisphenol A (BPA) and an aromatic diol. Surface investigation of films and the bonds between the epoxy functional group of silane compound and the curing agent and also cross-linking between them and the curing agent and oxide layer were carried out by optical microscopy images and ATR-IR spectroscopy. Corrosion resistance of these coatings was studied by electrochemical and accelerated corrosion (salt spray) experiments. Both optical microscopy and ATR-IR spectroscopy observations revealed that the surface of these coatings have not any crack and reduction of absorption peaks in the region of 750 and 906cm-1 and the presence of a peak at 936cm-1 were attributed to cross-linking between BPA and epoxy function of silane compound and oxide layer of metal support surface, respectively. Electrochemical and accelerated corrosion experiment results showed that these compounds have good corrosion resistance. Study of the effect of H2O and silane content on the degree of corrosion resistance by electrochemical experiments indicated that the completion of hydrolysis reaction and reduction of silane content (%TMOS) make improvement on corrosion resistance of organic-inorganic hybrid coatings.