Abstract:The objective of this study was to investigate the effect of crosslinking systems (conventional and efficient systems) on the contact mechanics and heat build-up of natural rubber (NR) tyre mimicking samples. The JKR (Johnson, Kendall and Roberts) experiment has been established to measure the contact mechanics in NR samples at different vulcanization systems. Work of adhesion obtained from JKR model is in good agreement with that calculated from contact angle measurement. From the contact mechanics point of v… Show more
“…Samples with a high NR concentration possess more network structure, generating the low hysteresis. This result is in good agreement with the existing literature, and the hysteresis of the rubber foam could be due to either the molecular friction of short molecules or the reduced network structure 8 , 48 . Figure 10 Dynamic mechanical analysis of various foam samples: ( a ) storage modulus, E ' , as a function of temperature, and ( b ) tan δ as a function of temperature.…”
Natural rubber (NR) foam can be prepared by the Dunlop method using concentrated natural latex with chemical agents. Most previous studies have focused on the thermodynamic parameters of solid rubber in extension. The main objective of this study is to investigate the effect of the NR matrix concentration on the static and dynamic properties of NR foams, especially the new approach of considering the thermodynamic aspects of NR foam in compression. We found that the density and compression strength of NR foams increased with increasing NR matrix concentration. The mechanical properties of NR foam were in agreement with computational modelling. Moreover, thermodynamic aspects showed that the ratio of internal energy force to the compression force, Fu/F, and the entropy, S, increased with increasing matrix concentration. The activation enthalpy, ∆Ha, also increased with increasing matrix concentration in the NR foam, indicating the greater relaxation time of the backbone of the rubber molecules. New scientific concepts of thermodynamic parameters of the crosslinked NR foam in compression mode are proposed and discussed. Our results will improve both the knowledge and the development of rubber foams based on the structure–properties relationship, especially the new scientific concept of the thermodynamical parameters under compression.
“…Samples with a high NR concentration possess more network structure, generating the low hysteresis. This result is in good agreement with the existing literature, and the hysteresis of the rubber foam could be due to either the molecular friction of short molecules or the reduced network structure 8 , 48 . Figure 10 Dynamic mechanical analysis of various foam samples: ( a ) storage modulus, E ' , as a function of temperature, and ( b ) tan δ as a function of temperature.…”
Natural rubber (NR) foam can be prepared by the Dunlop method using concentrated natural latex with chemical agents. Most previous studies have focused on the thermodynamic parameters of solid rubber in extension. The main objective of this study is to investigate the effect of the NR matrix concentration on the static and dynamic properties of NR foams, especially the new approach of considering the thermodynamic aspects of NR foam in compression. We found that the density and compression strength of NR foams increased with increasing NR matrix concentration. The mechanical properties of NR foam were in agreement with computational modelling. Moreover, thermodynamic aspects showed that the ratio of internal energy force to the compression force, Fu/F, and the entropy, S, increased with increasing matrix concentration. The activation enthalpy, ∆Ha, also increased with increasing matrix concentration in the NR foam, indicating the greater relaxation time of the backbone of the rubber molecules. New scientific concepts of thermodynamic parameters of the crosslinked NR foam in compression mode are proposed and discussed. Our results will improve both the knowledge and the development of rubber foams based on the structure–properties relationship, especially the new scientific concept of the thermodynamical parameters under compression.
“…Bound rubber was analysed by a previously reported method. 13,16 The vulcanisation characteristics of the rubber compound were evaluated by using a Moving Die Rheometer (TechPro, RheoTech MDþ, Cuyahoga Falls, OH, USA) at 150 C. Optimum cure time (t 90 ) was obtained at the time at which the rheometer torque increases to 90% of the total torque change following curing of rubber.…”
Section: Characterisation Of Rubber Compositesmentioning
confidence: 99%
“…Compared at the same ratio, they presented higher tensile strength but undesirable higher heat buildup. [11][12][13][14][15] Increasing the surface area and including surface treatment gave higher abrasion resistance, chemical adsorption or reaction, modulus (at elongation over 300%) and also heat build-up.…”
The effects of carbon black on the properties of rubber composites were studied in order to explore their value in producing low rolling resistance truck tires. Carbon black with different grades, N330 (coarser grade of 26–30 nm) and N220 (finer grade of 20–25 nm), was used as a reinforcing agent of natural rubber. The effects of different ratios of carbon black N330 at 40, 45, 50 and 55 parts per hundred rubber (phr) and N220 at 30, 35, 40 and 50 phr were investigated. Rubber composites with N220 had greater rubber/carbon black interaction than those with N330. The Mooney viscosity of rubber composite increased when the carbon black ratio increased. After vulcanisation of rubber, the samples were characterised by dynamic mechanical analysis, tensile strength and heat build-up. The results showed that the strength of rubber composites increased with increasing carbon black ratios. Interestingly, at the same bound rubber level, rubber composites with N220 presented lower dissipation energy, heat build-up and better mechanical properties than those with N330. This study indicated that reinforcement with an optimum amount of carbon black N220 would improve several desirable characteristics of rubber composites when used in low rolling resistance truck tires.
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