Preparation and characterization of an electromagnetic composite polypyrrole/polyethylene short filament geotextile

In this paper, firstly, polypyrrole was prepared by in situ polymerization using pyrrole as the monomer, hexahydrate ferric chloride as the oxidizer and dopant, and polyethylene geotextile as the substrate to prepare a polypyrrole/polyethylene short filament geotextile composite; secondly, the electromagnetic microwave absorption property and shielding property of the polypyrrole/polyethylene short filament geotextile composite were investigated; finally, the chemical structure of the polypyrrole/polyethylene short filament geotextile composite was characterized by Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), X-ray diffraction (XRD), and Raman test methods. The results show that the reflection loss value is up to the minimum value of –17.53 dB in the frequency range of 0–3 GHz and the best absorbing performance is obtained at the frequency of 1.12 GHz. In the frequency range of 0.95–1.25 GHz, the reflection loss value is less than –10 dB, and the electromagnetic wave is effectively absorbed. The shielding effectiveness value is up to the maximum value of 16.07 dB at the frequency of 1.19 GHz, that is, the shielding ability becomes strongest at the frequency of 1.19 GHz; otherwise, the shielding effectiveness is higher than 14 dB in the frequency range of 0.17–3.0 GHz. The FTIR, Raman, XRD, and DSC tests result show that polypyrrole has been successfully loaded on the polyethylene geotextile, improving the crystallinity and thermal stability property of the composite.

Enhancement of Heat Ageing Properties of Epoxidised Natural Rubber Blend

In recent years, automotive hose and belt specifications have changed, requiring longer product life in terms of swelling, wear and heat ageing. Diene-based rubbers, such as natural rubber (NR) and styrene-butadiene rubber (SBR), have been widely used in diverse industries. However, some apparent defects such as limited ageing resistance and large compression set, have been demonstrated in some rubbers cured by sulfur or peroxides. In the making of general and industrial rubber goods, short production and sufficient scorch time is crucial especially by using an injection moulding. In this work, blend of Epoxidised Natural Rubber (ENR 25) and Butadiene was developed with two types of curing systems namely Conventional and Efficient Vulcanisation system. The aim of the study is to produce a satisfactory heat resistance rubber compounds and adequate process safety for rubber manufacturing. Results showed that curing system applied significantly affected thermal stability property of the compounds. Modulus and hardness of the blends appeared to decrease progressively with ageing. However, greater thermal stability especially ageing at 100°C for 200h was observed with compound containing efficient curing system compared to conventional curing system which corresponded to the cross link density attributed by the torque value and dynamic mechanical analysis. The results on stiffness however was effected by the curing system applied. The influence of cure temperature on the chemical crosslink density on both cure systems are being investigated. The network results will be correlated with the technical properties.

Study on the thermal stability and ablation properties of metallic oxide-filled silicone rubber composites using uniform design method

The thermal stability and ablation properties of silicone rubber composites filled with Fe2O3, SnO2, CuO, MgO, and Al2O3 were researched using thermogravimetric analysis (TGA) and the oxyacetylene torch test. The effecting laws of metallic oxide on the thermal stability and ablation properties of silicone rubber composites were analyzed by uniform design method. TGA indicated that the thermal degradation process of silicone rubber composites took a two mass loss steps. The effecting order of metallic oxide on enhancing thermal stability property of silicone rubber composites in step 1 was MgO>SnO2> Fe2O3>Al2O3>CuO, whereas the order in step 2 was CuO> SnO2>MgO>Fe2O3>Al2O3. Furthermore, Fe2O3 and SnO2 had an evident synergistic effect on enhancing the thermal stability property and residual carbon of silicone rubber composites. The oxyacetylene torch test showed that the effecting order of metallic oxide on increasing ablation resistance property of silicone rubber composites in ablation process was CuO>MgO>Fe2O3>SnO2>Al2O3. Moreover, the line ablation rate of specimen 2 was 0.0499, which indicated that it had the best ablation resistance among all uniform samples. Furthermore, scanning electron microscopy also showed that the porous ceramic layer became much denser after the ablation process, and this will significantly improve the ablation resistance property.

Preparation, Characterization and Thermal Properties of Polyacrylonitrile/Alpha-Zirconium Phosphate Nanocomposites by Gelation/Crystallization

Nanocomposites of polyacrylonitrile (PAN) and Organophilic alpha-zirconium phosphate (OZrP) were prepared by gelation/crystallization. OZrP was prepared using cetyl trimethyl ammonium bromide (CTAB). The structure of PAN/OZrP nanocomposites was characterized by X-ray diffractometry (XRD) and high resolution transmission electron microscopy (HRTEM). The results showed that an intercalated or exfoliated structure was formed. Thermogravimetric analysis (TGA) was applied to characterize thermal stability property, which indicated that the thermal stability of PAN/OZrP nanocomposites was improved compared with that of pure PAN. HRTEM and Laser Raman spectroscopy were used to analyze the microstructure of the chars of PAN/OZrP nanocomposites.