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Properties and Degradation of Nitrile Rubber
Published in Nicholas P. Cheremisinoff, Elastomer Technology Handbook, 2020
Susmita Bhattacharjee, Anil K. Bhowmick, Bhola Nath Avasthi
Nitrile rubber is manufactured by emulsion copolymerization of butadiene and acrylonitrile.1,2 The monomers are emulsified in water and a catalyst is added to generate free radicals and initiate polymerization. Generally, anionic emulsifiers such as alkali salts of “fatty” carboxylic acids, sulfates, or sulfonates are used in nitrile rubber polymerization. They can be washed out during coagulation and de watering. The catalyst is a water-soluble peroxide activator1 such as potassium, ammonium salt of persulfuric acid, organic peroxides, hydroperoxides, and peracids. The polymer chain is initiated when a free radical formed by decomposition of a catalyst reacts with a monomer molecule. The initiated chains quickly leave the water phase and enter the micelles and the polymer chain grows. The catalyst is inactivated by a short stop and the residual monomers are removed from the emulsion. Usually, the short stops are water-soluble reducing agents such as sodium hydrogen sulfite, sodium dithionite, hydroxy lamine, hydrazine and its salts, or sodium dimethyldithiocarba-mate. A stabilizer or antioxidant is added to the latex for protection during drying and storage. Bis-p-cresol and alkylated phenols are the most effective stabilizers. The polymer is coagulated with an aqueous solution of inorganic salt. The rubber crumb is washed with water several times and dried by hot air.
Plastics
Published in Arthur Lyons, Materials for Architects and Builders, 2019
Nitrile rubber is formed by the copolymerisation of acrylonitrile and butadiene. It is water- and oil-resistant, so it is frequently used in structural movement joints which may be subject to surface oil.
Rubber-Based Adhesives
Published in A. Pizzi, K. L. Mittal, Handbook of Adhesive Technology, 2017
A.A. Shybi, Siby Varghese, Hanna J. Maria, Sabu Thomas
Nitrile rubbers are rubber-like copolymers of unsaturated nitriles, such as acrylonitrile, with dienes (mainly butadiene). The oil resistance and adhesive properties of nitrile rubber increase with an increase in nitrile content [62]. Adhesives based on nitrile rubber latex and resorcinol–formaldehyde latex to bond nitrile rubber to glass fibers and organic synthetic fibers were prepared by Hisaki et al. [63]. The adhesive formulation they used also contained carbon black as filler, and a vulcanizing agent. It was found that the adhesive gave better initial adhesion strength than conventional adhesives for bonding fibers. An adhesive from hydrogenated nitrile rubber latex blended with chlorinated paraffin wax was used to coat textiles [64]. An adhesive composition based on hydrogenated nitrile–butadiene rubber latex with resorcinol–formaldehyde resin and ethylene urea compound showed excellent degradation resistance and high tackiness, and was used to bond rubber and glass [65]. To produce a toothed belt with excellent wear and water resistance, Isshiki et al. prepared an adhesive comprised of a self-cross-linking carboxylated unsaturated nitrile rubber latex with resorcinol–formaldehyde [66].
A design of fully soft robot actuated by gas–liquid phase change
Published in Advanced Robotics, 2019
Yuto Nishikawa, Mitsuharu Matsumoto
Silicone rubber made by crosslinking PDMS (polydimethylsiloxane) is mainly used as a body material of soft robot due to its high flexibility and heat resistance. It is also used in the medical field due to high biocompatibility. However, gas permeability is much higher than other rubbers. Hence, we avoided to use it as a chamber as it contains volatile substances. Nitrile rubber has good features in oil resistance, abrasion resistance and aging resistance. It is used for work gloves due to its features. Although it is inferior to ozone resistance and cold resistance, gas permeability is very small and gas is difficult to pass through. Natural rubber is also a good candidate for the chamber. It is widely used in various scenes and has high mechanical strength and small gas permeability.
A proposal of a new rotational-compliant joint with oil-hydraulic McKibben artificial muscles
Published in Advanced Robotics, 2018
Ryusuke Morita, Hiroyuki Nabae, Gen Endo, Koichi Suzumori
The newly developed HAM, as well as an ordinary McKibben artificial muscle, consists of an inner rubber tube and an outer sleeve woven with fibers. Figure 3 shows an overview of the HAM. As shown in Figure 4, the operation principle is that the tube expands by applying a fluid pressure inside the rubber tube, and the knitting angle of the outer sleeve increases, so that it contracts in the axial direction. The rubber tube is made of an oil-resistant nitrile rubber [23] which we have recently developed. The properties of this rubber are shown in the S–S curve of Figure 5. The outside diameter is 14.7 mm and the inside diameter is 9.5 mm. The rubber has a deformation ratio of 600% and is oil resistant, which makes it suitable for the HAM that drives while deforming the rubber. In addition, the sleeve is woven with aramid fibers with 1.0 mm of diameter and assembled at a knitting angle of 25. The outer diameter of a HAM is approximately 17 mm, the length of the contraction part is 400 mm, and the length between the mounting holes of both terminals is 500 mm. In the crimping structure, the tensile force applied to the fibers is taken directly by the metal terminal [24]. This is based on the papers[5] [22]. By combining the newly developed highly oil-resistant nitrile rubber, sleeve made of high-strength aramid fibers and crimping structure, we achieved the HAM having a high oil-pressure resistance of up to 7 MPa. The applied pressure is 7 MPa at maximum. Using the newly developed highly oil-resistant nitrile rubber in combination with high-strength aramid fibers and crimping structure corresponding to high pressure, we were able to attain pressure and oil resistance at high levels.