Iranian Polymer Journal
Year:2008 | Volume:17 | Issue:8|Papers Count:6

This paper is devoted to review of the publications on the finite element modeling of rolling tyres performed during the past two decades. Starting with the description of the scope and motivation behind this work, a brief history of the finite element modelling of tyres is given. Then, a comprehensive review on the published works on modelling techniques of the simulation of the rolling tyres is presented. The applied aspects of the subject including the energy loss (rolling resistance) and temperature prediction, interaction between tyre and road, noise, failure, and stability are considered too. It is then followed by introducing the most applied computer codes available in the numerical and computational market. A summary on the published works with particular focus to compare different developed methods and especially the current situation of the applied aspect of the finite element modelling of rolling tyres are presented and discussed. Finally, a conclusion with some remarks is drawn.

Process ability, morphology, optical, and mechanical properties of acrylonitrilebutadiene- styrene (ABS) polymers were studied by simulation of its reprocessing and service life. A series of ABS samples were prepared by melt-mixing of SAN and g-ABS. All specimens were characterized by melt mass-flow rate (MFR) measurements, tensile testing, impact strength (Izod), Fourier transform infrared (FTIR) spectroscopy, colour spectrophotometry (data of L*, a*, and b*) and transmission electron microscopy (TEM) techniques. Reprocessing and thermo-oxidative ageing clearly alter the elongation-at-break, impact strength and yellowness index of the polymers. These changes observed at a macroscopic scale have been related to chemical alterations in the structure of ABS. TEM Micrographs indicated no significant changes in the status of rubber (PB) phase. The PB phase was demonstrated to be the initiation point of the degradative processes induced by processing, service life, and recycling. The results of the FTIR showed that upon processing of ABS, cross-linking and chain scission of rubber phase was the governing degradation and yellowing mechanisms. Thermo-oxidative ageing degradation has affected the degree of yellowing of the polymer more severely. Thus, it may be deduced that the changes occurring during service life of ABS are part of the life cycle which mostly affect its further recycling possibilities and performance in second-market applications.

The widespread use of cross-linked polyethylene (XLPE) as insulation in the manufacturing of medium and high voltage cables may be attributed to its outstanding physical, chemical, mechanical, and electrical properties. However, it is well known that degradation under service conditions is the major problem in the use of XLPE as cables insulation. Especially, thermal oxidative degradation produces low molecular weight and oxygenated products. Several diagnostic measurements have been used in this study in order to characterize XLPE behaviour under thermal ageing. Firstly FTIR has been conducted on fresh and aged samples in order to reveal the effect of thermal ageing on the chemical changes which take place in the XLPE structure. The main changes are the formation of carbonyl groups (aldehyde, ketone, etc.). Use of DSC analysis shows the effect of ageing on the melting peak temperature Tm, melting enthalpy DHm and lamellar thickness. In the last part we have applied X-ray diffraction to reveal the variations in percentage of XLPE crystallinity or addition of any new crystalline phase under thermal ageing. The obtained results showed that thermal ageing at temperatures above the melting temperature of XLPE has a great effect on the material structure.

In the present work, two kinds of CPVC carboxylated ionic copolymers were prepared by a new method. First, a graft copolymer (CPVC-cg-AA) comprising of polyacrylic acid (PAA) as branched chains and chlorinated polyvinyl chloride (CPVC) as backbone was synthesized by in-situ chlorinating graft copolymerization (ISCGC).Second, the acid groups of the graft copolymer were neutralized by sodium hydroxide and aluminum hydroxide, respectively in order to prepare carboxylated ionic copolymers.The carboxylated ionic copolymers have been studied by FTIR, 1H NMR, DSC, and DMA techniques and also their mechanical and swelling properties were determined. The results have confirmed the existence of the ionic copolymers by the characteristic peak at 1620 cm-1 in FTIR spectra and changes in chemical shift in 1H NMR. Compared with Al ionic copolymer, Na ionic copolymer has higher glass transition temperature (Tg) through DSC, DMA tests and it has shown better mechanical properties.Na ionic copolymer can be solved in tetrahydrofuran (THF) while Al ionic copolymer only swells in THF.

This paper demonstrates the synthesis and characterization of a new functional acrylic monomer, 7-acryloyloxy 4-methyl coumarin (AOMC) and its copolymers with methyl acrylate (MA). The polymerization was conducted by free radical polymerization technique using AIBN as an initiator at 70±1oC. The resulting polymers were characterized by FTIR and 1H NMR techniques, solubility study and their inherent viscosity measurements. Gel permeation chromatography (GPC) was used to find out the molecular weights of homopolymers and copolymers. The number average molecular weight of copolymers was found to increase with increase in mole fraction of AOMC. The polymers showed moderate thermal stability which were determined by thermogravimetry (TG) and differential thermal anlaysis (DTA). Copolymers' compositions were determined by 1H NMR spectra. Further, the linearization method of Finemann-Ross (rAOMC=0.7315; rMA=0.8439), Kelen-Tudos (rAOMC=0.7734; rMA=0.8650), and extended Kelen-Tudos (rAOMC=0.7663; rMA=0.8554) were employed to calculate the monomer reactivity ratios. These values suggest that MA is more reactive than AOMC. Antimicrobial activities of different copolymers synthesized were also studied against different bacteria, fungi, and yeasts and it was observed that their antimicrobial activities differ from each other depending on the AOMC content in copolymers.

Novel polypyrrole (PPy) hollow micrometer-sized Y-junctions and capsules were selectively prepared via in-situ polymerization. The rod junctions or particles of benzyl orange (BO) precipitates were used as reactive templates which were obtained by adding HCl or FeCl3 to BO aqueous solution, respectively. PPy formed on the surface of the templates and the templates could be removed easily by routine washing with water for BO-HCl or by direct self-degradation for BO-FeCl3. Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) results showed that, the PPy hollow Y-junctions and capsules with morphologies similar to those of templates were obtained after templates removal. The effects of pH, the speed of the oxidant addition and the reaction temperature on morphology of the PPy microstructures were investigated and the special hollow structures could be observed always under the appropriate conditions. It was found that more PPy Y-junctions or capsules were obtained when the polymerization rate was decreased either by controlling the speed of oxidant addition or the reaction temperature, implying that the formation of PPy micro/nanostructures by this BO template method is a relatively slow process.Moreover, the structure and property of the PPy microstructures have been characterized by Fourier transform infrared spectrometry (FTIR) and X-ray diffraction (XRD) techniques and electric conductivity measurements.