HXNBR Coating for Improving Aging Resistance of Natural Rubber Products

2006 ◽  
Vol 79 (4) ◽  
pp. 553-560 ◽  
Author(s):  
Rani Joseph
Keyword(s):  
Mechanical Properties ◽  
Natural Rubber ◽  
Room Temperature ◽  
Oxidative Degradation ◽  
Thin Coating ◽  
Oil Resistance ◽  
Aging Resistance ◽  
Natural Rubber Vulcanizates ◽  
Good Heat ◽  
Accelerator System

Abstract HXNBR (Hydrogenated Carboxylated Nitrile Rubber) has very good heat ageing resistance and oil resistance. A novel accelerator system is designed to bring about the vulcanization of HXNBR at room temperature. The room temperature cured samples showed good mechanical properties equivalent to those of high (150 °C) temperature cured samples. Natural rubber vulcanizates are highly prone to oxidative and ozone degradation. The oil resistance of natural rubber vulcanizates is also very low. The oil resistance, ozone and oxidative degradation resistance of natural rubber vulcanizates are considerably improved by placing a thin coating of HXNBR over it.

Mechanical and Swelling Behavior of Double Networked Natural Rubber Cured Using a New Binary Accelerator System

2007 ◽  
Vol 80 (5) ◽  
pp. 809-819 ◽  
Author(s):  
C. V. Marykutty ◽  
G. Mathew ◽  
Sabu Thomas
Keyword(s):  
Mechanical Properties ◽  
Natural Rubber ◽  
Transverse Direction ◽  
Tensile Elongation ◽  
Longitudinal Direction ◽  
Chain Orientation ◽  
Swelling Studies ◽  
Natural Rubber Vulcanizates ◽  
Double Networks ◽  
Accelerator System

Abstract The concept of double networks, which impart chain orientation to elastomers, is a rather new idea. Double networks were induced in natural rubber vulcanizates cured with different accelerator systems. Double networked natural rubber with different extensions cured with N-cyclohexyl benzothiazyl sulphenamide (CBS) and 1-phenyl 5-ortho -tolyl 2,4 dithiobiuret was studied and the effect of extension on the mechanical properties and swelling was analyzed. The extent of chain orientation was analyzed through anisotropic swelling studies. The modulus, tensile strength and tear strength showed an increase with increased residual extension ratio. The effect was more predominant in the longitudinal direction than in the transverse direction. The ultimate tensile elongation showed a slight deterioration. It was revealed that the formation of double networks with higher residual extension ratios restricted the entry of the solvent. Based on the studies it was concluded that residual extension has a profound effect in determining the final properties of vulcanizates.

Influence of Crosslink Characteristics Induced by Aromatic-Based Antioxidants on the Swelling and Stress-Strain Behavior of Natural Rubber Vulcanizates

2003 ◽  
Vol 76 (2) ◽  
pp. 334-347 ◽  
Author(s):  
Tarek M. Madkour ◽  
Rasha A. Azzam
Keyword(s):  
Natural Rubber ◽  
Crosslinking Agent ◽  
Oxidative Degradation ◽  
Thermal Oxidative Degradation ◽  
Stress Strain ◽  
Strain Behavior ◽  
Strain Induced Crystallization ◽  
Elastomeric Chains ◽  
Natural Rubber Vulcanizates ◽  
Induced Crystallization

Abstract Stress-strain measurements were performed on dry and swollen natural rubber vulcanizates prepared using both sulfur as the crosslinking agent and aromatic-based bound antioxidants acting as a second crosslinking agent. The aromatic-based antioxidants were synthesized and analyzed spectroscopically in order to relate the final behavior of the vulcanizates to the nature of the crosslink characteristics. The anomalous upturn in the modulus values of these networks in response to the imposed stress was shown to persist in the dry as well as the swollen state. Since the swollen elastomeric chains cannot undergo a strain-induced crystallization, the abnormal upturns in the modulus values in an absence of a filler were explained on the basis of the limited extensibility of the short chains of networks prepared using two different crosslinking agents in line with earlier modeling predictions. Remarkably, the swelling experiments revealed the increase in the crosslink density of the networks in the early stages of the thermal oxidative degradation procedure indicating a post-cure of the chemically bound antioxidants to the elastomeric chains, which incidentally corresponds to a maximum in the modulus values of the networks. The rheological and other mechanical properties such as the hardness were shown not to have been affected as a result of the incorporation of the chemically bound antioxidants.

Kinetics of Crosslinking and Network Changes in Natural Rubber Vulcanizates with a Dithiodimorpholine Based Accelerator System

1980 ◽  
Vol 53 (5) ◽  
pp. 1015-1022 ◽  
Author(s):  
A. K. Bhowmick ◽  
S. K. De
Keyword(s):  
Natural Rubber ◽  
Rate Constants ◽  
Crosslink Density ◽  
Curing Temperature ◽  
Side Reactions ◽  
Filler Surface ◽  
Natural Rubber Vulcanizates ◽  
Kinetics Of ◽  
Accelerator System

Abstract Kinetics of crosslinking and network changes in unfilled and filled natural rubber vulcanizates with a dithiodimorpholine based accelerator system have been studied at 150° and 180°C. Results show that addition of HAF black enhances the polysulfidic crosslinks as well as the total crosslinks. This has been explained with the help of Coran's model wherein HAK black increases the rate constants. It is likely that the filler surface prevents desulfuration and undesirable side reactions involving the crosslink precursors. Increase of curing temperature by 30°C lowers the total crosslink density and increases the sulfur inefficiency.

Influence of Reaction Conditions on the Properties of Nano-matrix Structure Formed by Graft-Copolymerization of Acrylonitrile onto Natural Rubber

2013 ◽  
Vol 844 ◽  
pp. 365-368 ◽  
Author(s):  
Kontapond Prukkaewkanjana ◽  
Seiichi Kawahara ◽  
Jitladda Sakdapipanich
Keyword(s):  
Mechanical Properties ◽  
Natural Rubber ◽  
Graft Copolymerization ◽  
Monomer Concentration ◽  
Proton Nuclear Magnetic Resonance ◽  
Resonance Spectroscopy ◽  
Matrix Structure ◽  
Oil Resistance ◽  
Wide Range ◽  
Initial Monomer

Natural rubber (NR) is one of the most important agriculture products of Thailand, which is an important material with unique and special characteristics used in wide range of applications such as mechanical properties, excellent strength, and elasticity. However, it is inferior in oil resistance due to the presence of hydrogen and carbon in its structure. This inherent drawback of NR has limited its application in industry. In order to expand the use of NR, this research is interested to improve the oil resistance of NR without loss of outstanding properties by grafting NR with acrylonitrile (AN) monomer to form the nano-matrix structure. The influences of the initial monomer concentration and initial initiator concentration were investigated. These effects on structure, mechanical properties and oil resistance properties were studied by Fourier transform infrared spectroscopy and proton nuclear magnetic resonance spectroscopy, tensile machine, and swelling in toluene, respectively. It was found that the tensile strength and oil resistance properties of graft copolymerization of AN onto NR increased with increasing the percentage grafting efficiency of acrylonitrile monomer.

Mechanical Properties of Natural Rubber and Chloroprene Rubber Latex Blends

2011 ◽  
Vol 239-242 ◽  
pp. 1601-1604 ◽  
Author(s):  
Xiao Xue Liao ◽  
Hai Sheng Tan ◽  
Ming Chao Luo ◽  
Bing Tang ◽  
Shuang Quan Liao ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Natural Rubber ◽  
Natural Rubber Latex ◽  
Physical And Mechanical Properties ◽  
Epoxidized Natural Rubber ◽  
Latex Film ◽  
Rubber Latex ◽  
Oil Resistance ◽  
Chloroprene Rubber

The effects of the ratios of natural rubber latex (NRL)and chloroprene rubber latex(CRL) and the type of compatibilizer on physical and mechanical properties of latex film were researched.The oil resistance of vulcanized latex film was tested. The compatibility of the latex blends was also analyzed by TG/DTG method.The results showed that properties of latex film were best when ratio of NRL/CRL was 75/25. As the CRL content increased, oil resistance of latex film was improved. Epoxidized natural rubber latex improved compatibility of NRL and CRL blends.

Aromatic and Epoxidised Oil Curing and Rebound Resilience Characteristic and their Humidity Effect of Hardness on NR Vulcanizates

2013 ◽  
Vol 812 ◽  
pp. 138-144 ◽  
Author(s):  
Mohamed Rahmah ◽  
Wan Zain Norazira ◽  
Shafie Nur Ashyikin ◽  
Mohd Nurazzi Norizan
Keyword(s):  
Natural Rubber ◽  
Physical Properties ◽  
Room Temperature ◽  
Rubber Compound ◽  
Humidity Effect ◽  
Humidity Level ◽  
Cure Time ◽  
Humidity Chamber ◽  
Overall Performance ◽  
Natural Rubber Vulcanizates

Recently, aromatic oil (AO) is one of the substances that is typically used as a processing aid especially for high filler loadings in formulating rubber compound. Aromatic oil has disadvantages in that, it is hazardous to environment, toxic and has been labeled as carcinogenic. In this research, an epoxidised oil (EO) and aromatic oil were used to investigate the effect incorporation of oil onto the SBR/NR natural rubber vulcanizates (NR). From the result obtained, EO showed shorter cure time and scorch time as the oil loading were increased up to 20 pphr of EO. Physical properties such as hardness and rebound resilience of NR/EO vulcanisate were also investigated upon exposure to different humidity level in humidity chamber. At room temperature, the hardness of EO loading onto the SBR/NR vulcanisate is lower than AO loadings. Hardness was slightly decreased with increasing rate of humidity. There is great difference in hardness and rebound resilience values between AO and EO. Both hardness and rebound resilience were not affected by humidity. This implies the existence of good filler interaction with EO and rubber which do not impart changes in the hardness and resilience properties of rubber compound. Epoxidised oil has great promising potential to replace the carcinogenic aromatic oil as it has good overall performance and renewable in nature .

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