Papers by Keyword: Silicone Rubber

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Authors: Nurul Nadiah Azmi, Ilya Izyan Shahrul Azhar, Jamaluddin Mahmud
Abstract: Skin is an important organ which provides multiple functions. Thus, if skin fails i.e. due to burns or diseases, body will lose the protection provided by skin against infections and the harmful outer environment. Due to that, synthetic skin is seen as a very important alternative in the future. A number of studies have been carried out to understand skin’s basic functions and behaviour as its mechanical properties and behaviour are important in various fields. Nevertheless, to date no breakthrough has been reported. Therefore, this paper aims to briefly review and outline a framework which ultimately will lead to the synthesising silicone-hydrogel materials that potentially becoming a skin substitute. The newly synthesised composite materials will be tested mechanically to characterise its behaviour based on Ogden hyperelastic model. It could be emphasised that the present study is significant and will contribute to the body of knowledge in the area of skin mechanics.
Authors: Guo Li, Jin Zhu Tan, Jian Ming Gong
Abstract: Silicon rubber is a potential material for gaskets in proton exchange membrane (PEM) fuel cell. So its long term stability and durability is crucial to the electrochemical performance of fuel cell especially in an acidic, high temperature, humid environment. In present paper, the aging process of silicon rubbers has been studied in one simulated PEM fuel cell medium and two accelerated durability test (ADT) mediums for short time test at 70oC and 90oC, respectively. Effect of exposure time, temperature and exposure medium on aging of silicone rubber is also compared. Weight loss is measured by electronic balance; topographical changes on samples’ surfaces are monitored by optical microscopy; Attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy was employed to study the surface chemistry of samples before and after exposure over time. The results show that the weight loss increased over time. Surface conditions of samples change over time from initially smooth to rough, crack appearance and finally crack propagation through Optical microscopy. ATR-FTIR results show that the surface chemistry changed significantly via de-crosslinking and chain scission in the backbone for materials over time. The aging degree is severe at high temperature or in high concentration acidic solution over time.
Authors: Chao Wang, Jun Xue Ren, Yu Liu, Wen Qiang Hao, Jing Xian Yang
Abstract: In order to study the performance on silicone rubber elastomer in small-size flexible joint at different temperatures, a series tests for two miniature flexible joints (joint-SR1 and joint-SR2) with the same structure and different formula of silicon rubber elastomer (phenyl silicon rubber and dimethyl silicon rubber) were conducted. Axial compressive stiffness and bending stiffness at various temperatures (-60 °C~20 °C) and vessel pressures (1MPa~8MPa) were studied. Results show that the axial compressive stiffness and bending stiffness of joint-SR1 remain stable throughout the temperature range of-60 °C~20 °C, while those remain stable throughout the temperature range of-40 °C~20 °C and become to be infinite at-50 °C due to the elastic failure of elastomer material for the joint-SR2. Analysis indicates that the reason that elastomer of joint-SR2 lost elasticity at-50 °C is not glass-transition but crystallization. The phenomenon of elastic failure did not appear throughout the temperature range-60 °C~20 °C for the joint-SR1 elastomer is due to the existence of phenyl side-group substitute. The modified chain content of silicone rubber not only affects the process of crystallization inhibition but also the crystallization rate. The rubber with phenyl or other bulky side-group could destroy the crystal of silicone rubber at low temperatures, which is beneficial to be applied in small-size flexible joint.
Authors: S.H. Gao, Y. Liu, M.K. Lei, Li Shi Wen
Abstract: Silicone rubber (SIR) samples are exposed to CF4 capacitively coupled plasma (CCP) and inductively coupled plasma (ICP) at radio frequency (RF) power of 60–200 W for a treatment time up to 20 min, respectively. Static contact angle is employed to estimate the change of hydrophobicity of the silicone rubber modified by the two coupled types of CF4 RF plasma. A milder enlargement of static contact angle of SIR samples modified by ICP treatment is observed compared with that by CCP treatment. The hydrophobicity of the modified SIR surface by CCP treatment increases to a maximum, and further decreases toward the hydropholicity. The higher self-bias on the SIR samples being modified by CCP treatment than that by ICP treatment leads to the more dramatic physical and/or chemical reaction on the SIR surface, resulting in the competition between fluorination and ablation or etching.
Authors: Sufiah Mohamad Yahya, A. Azmi, Sufizar Ahmad, Hariati Taib
Abstract: The study investigates the effects of various contents of rice husk silica (RHS) on mechanical properties of polysiloxane (POS) sheet composite. The polysiloxane sheet composites filled with 5wt%, 10wt%, 15wt% and 20wt% of RHS were fabricated using casting technique at room temperature. The polysiloxane sheet reinforced RHS (POS-RHS) composites were characterised using thermogravimetry analysis (TGA), Fourier Transformation Infrared Spectroscopy (FTIR) and tensile test to determine the thermal and mechanical properties. It was found that the RHS as filler in polysiloxane is improvement in mechanical properties and the curve degradation of POS and POS-RHS are similarly. By using FTIR was shown the affect of Si and O bonding from RHS as filler.
Authors: Ying Gang Bu, Hideyuki Kinjo, Kazuaki Oyaizu, Kaname Inoue, Tsutom Mizuno, Zhi Hui Duan
Abstract: This paper introduced a novel actuator constructed by a flexible torsion spring with molded silicone rubber. The torsion spring is fixed at the ends to obtain the high rigidity and is molded by a silicone rubber material to achieve the high reliability. The actuator has the resonant frequency of f0=59Hz on the scanning direction and fβ =239Hz on the longitude direction. The maximal stress is 0.168MPa compared to the yield strength of 4.3MPa and the predicted safety factor is 25.6.
Authors: Elena Valentina Stoian
Abstract: Conductive plastics are attracting more and more interest in electronics due to their light weight and inability to rust, which are common problems associated with metals. In this work silicone rubbers reinforced with conductive fillers have been fabricated for use in various applications in electronics, telecommunications, and electronics enclosures, or to protect human factor, namely protective clothing. This paper presents the results of experimental determinations concerning electromagnetic field attenuation in materials containing micro-particles of nanocarbon in their structure. To know the effect of shielding effectiveness of electromagnetic field electromagnetic absorbents were performed by transmission measurements of attenuation in the frequency range 1-18 GHz. The goal of present paper consits in the realization a composit material with polymeric matrix. The materials were characterized by transmision diminishing carried out, relative permittivity, compression test and electrical conductivity.
Authors: Guo Li, Jin Zhu Tan, Jian Ming Gong
Abstract: The long term stability and durability of gaskets made of silicone rubber in proton exchange membrane fuel cell (PEMFC) has important effect on the sealing and the electric-chemical performance of the fuel cell. In present paper, the time-dependent chemical degradation of a silicone rubber was studied in three simulated PEMFC environments. The test temperature was selected and used at 90°C in this study according to the actual PEM fuel cell operation. Optical microscopy was used to show the topographical changes on the sample surface. Attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy was employed to study the surface chemistry of the gasket material before and after exposure to the simulated PEM fuel cell environments over time. The results show that the weight loss increased with the exposure time for the samples. Optical microscopy reveals that the surface conditions of the samples changed over time from initially smooth to rough, crack appearance and finally crack propagation. The ATR-FTIR results show that the surface chemistry changed significantly via de-crosslinking and chain scission in the backbone for the material over time.
Authors: Chil Chyuan Kuo, Min Hsiang Wu, Ming Yang Lai
Abstract: Silicone rubber mold is frequently used in the indirect tooling. Automatic vacuum casting system is widely used to degas in the manufacturing of silicone rubber mold, but the cost of hardware is very expensive. A low-cost automatic vacuum degassing system is designed, build and test in this study. Optimized parameters for degassing process are investigated. The saving in the degassing time is about 23.4%.This system offers many advantages such as reducing human error of operator, reducing noise and air pollutions derived from the vacuum pump of the vacuum casting system.
Authors: Antal Huba, László Molnár, András Czmerk, Tamás Fischl
Abstract: The silicone elastomers offer in our days new perspective for the construction in the precision engineering and in the medicine because of their special mechanical, electrical, optical and chemical properties. Since the essential material parameters like storage modulus and loss modulus depend on temperature and frequency explicit it is important for simulations to know these characteristics. This report is about determining of relaxation behaviour of silicone rubbers and about finding the mathematical relation to describe time-temperature equivalence of silicone elastomers. As conclusion we can declare that the common used Williams–Landel-Ferry equation to describe temperature and time dependent behaviour of polymers is not applicable for silicone rubbers.
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