No abstract

Potential of Sumilink-200 was investigated in a typical natural rubber-based tread compound in connection with its ability to act as a coupling agent for carbon black to reduce hysteresis loss of the compound. Optimum physical properties were obtained at 2 phr loading of Sumilink-200. At this loading, tensile modulus at 300% elongation improved by 9.6% with a reduction in visco-elastic energy dissipation (loss tangent) at 60°C by 8.3% over the control compound. The abrasion resistance properties of the compounds found to remain unaffected with the introduction of Sumilink-200.

Sulfidic linkages that are formed during the vulcanization process of natural rubber (NR) are unstable at a higher temperature and can be reversed into conjugated diene. To overcome such issue and to build a compound that is hostile to inversion and with increasing service life, anti‐reversion agent (ARA), for example, N,N′‐4,4′‐diphenylmethyene bismaleimide (BMDM), is added into the formulation. This work explains the conjugation reaction mechanism of conjugated diene and BMDM by means of gas chromatography–mass spectrometry and Fourier transform infrared spectroscopy. The first phase of this study is associated with the change in ARA dosage keeping ZnO dosage the same. It is observed that 5 phr of BMDM and 2 phr ZnO combination (ARA4) shows lowest reversion at 160°C. The modulus value at 300% elongation increased 12% by the incorporation of BMDM as compared to the compound of no BMDM (ARA1). The second part is all about keeping BMDM dosage the same at 5 phr level and varying ZnO phr by 3, 4, and 5. From the overall results, it is observed that at a suitable dosage of BMDM and ZnO (5 phr BMDM and 3 phr ZnO combination [ARA5]), least reversion can be achieved and vulcanizates containing optimized BMDM and ZnO show better retention properties after aerobic aging as compared to ARA1.

Physico-mechanical and dynamic mechanical properties of typical solution grade styrene-butadiene rubber (S-SBR) and polybutadiene rubber (PBR) based tiretread compound were investigated by partially replacing highly dispersible (HD) silica with naturally occurring α-cellulose. Fourier transform infrared spectrum detected abundance of hydroxyl group in α-cellulose, which has created keenness to investigate its reinforcement characteristics in an S-SBR and PBR based compound. Scanning electron microscope and transmission electron microscope were employed to investigate the microstructure and dispersion of α-cellulose at higher magnification. Thermo-gravimetric analysis was performed to understand the degradation behavior of α-cellulose. Differential scanning calorimeter was engaged to detect phase transition and degree of purity of α-cellulose. An increase in cure rate was observed with partial replacement of HD silica by α-cellulose. The cure rate index was increased by 13% over control one at 10% replacement of silica with α-cellulose. It was noticed that at an optimum level of replacement (10%), α-cellulose containing compounds exhibited lower viscoelastic energy dissipation (both loss modulus [E 00 ] and loss tangent [tan δ]) at the slight expense of tensile moduli. Beside these, substitution of silica with α-cellulose found to have no effect on wet grip property of the compounds.

A polyuronide hemicellulose has been isolated from the chlorite holocellulose of jute fiber. It constitutes about 75% of the hemicelluloses of jute and appears to consist of one molecule of monomethyglucuronic acid linked with six of anhydroxylose, which is the repeating unit. On hydrolysis, it gives methylaldobiuronic acid, which has been investigated as the barium salt; complete hydrolysis of this acid has not been possible. Results of the bromine oxidation of the barium salt of methylaldobiuronic acid indicate that the acid is at one end of the chain, and its hemiacetal group forms the glucosidic link with xylose. There is no free xylan in jute fiber. The only other sugar detected so far in the alkali extract of jute holocellulose is galactose, which occurs only in small amounts. Methyluronic acid seems to be incapable of yielding fur fural on distillation with 12% hydrochloric acid. This methyluronic acid-xylose complex is the main, if not the only, acidic constituent of the fiber, to which, apparently, is due its natural affin ity for basic dyes.