Materials Science articles list

Liquid isoprene rubber as a safe processing aid in natural rubber compounds

In order to overcome the carcinogenic ‘polycyclic aromatic hydrocarbon’ emission from aromatic oils, which are restricted in European countries since 2010, various efforts have been made to replace the aromatic oil in rubber-based compounds either fully or partially. The authors in the present work have used liquid isoprene rubber (LIR50 or LIR) as a reactive plasticizer in natural rubber (NR) compound at different loadings (2, 4, 6 and 8 phr) and have studied its effect on viscosity, curing characteristics and physico-mechanical properties. These results were compared with the control compound containing conventional aromatic oil as plasticizer. From the experimental data, it was noticed that, the minimum torque for control compound was 0.33 dNm and that for LIR based compounds ranged between 0.16 to 0.56 dNm. The LIR based compounds exhibited slightly higher Mooney viscosity but offers the same scorch safety. The study supports the utility of LIR as a promising alternative, as revealed by the comparable rheological and physico-mechanical properties attained with the usage of appropriate quantity of LIR, unlike the other alternatives of the previous investigations that usually showed a property difference. Keywords: aromatic oil, liquid rubber, reactive plasticizer, safe processing oil.

Chandresh M. P.

Surface modification of anhydrous borax with stearic acid by wet coating method

The wet coating of anhydrous borax powders with stearic acid (SA) to reverse their inherent hydrophilic surface properties was investigated. The coating procedure was based on the results from a previous study that revealed that the stearic acid solution (2 wt. % SA) mixed for 60 minute at 750 rpm on the magnetic stirrer was sufficient for the surface modification of anhydrous borax. For the experiments, stearic acid powders were first dissolved in water at 80 °C. The mixture obtained by adding anhydrous borax powders to this solution was vigorously mixed on a magnetic stirrer to initiation and completion the surface modification. Each of these solutions was then filtered using a filter paper to separate the undissolved particles, and the residue on paper was dried at 50 °C for 48 h until constant weighing was obtained. Wettability has been accepted as a key parameter for success in wet coating treatment. This parameter gained via the experimental characterization technique was used for an evaluation of the powder properties. The degree of wettability of anhydrous borax powders was measured and compared both after their surfaces were coated with stearic acid and after they were treated with water for a certain period of time in an aqueous environment. The stearic acid coating made the powder hydrophobic and this property was highly preserved after washing.

Journal of Characterization

Surface modification of anhydrous borax with stearic acid by wet coating method

The wet coating of anhydrous borax powders with stearic acid (SA) to reverse their inherent hydrophilic surface properties was investigated. The coating procedure was based on the results from a previous study that revealed that the stearic acid solution (2 wt. % SA) mixed for 60 minute at 750 rpm on the magnetic stirrer was sufficient for the surface modification of anhydrous borax. For the experiments, stearic acid powders were first dissolved in water at 80 °C. The mixture obtained by adding anhydrous borax powders to this solution was vigorously mixed on a magnetic stirrer to initiation and completion the surface modification. Each of these solutions was then filtered using a filter paper to separate the undissolved particles, and the residue on paper was dried at 50 °C for 48 h until constant weighing was obtained. Wettability has been accepted as a key parameter for success in wet coating treatment. This parameter gained via the experimental characterization technique was used for an evaluation of the powder properties. The degree of wettability of anhydrous borax powders was measured and compared both after their surfaces were coated with stearic acid and after they were treated with water for a certain period of time in an aqueous environment. The stearic acid coating made the powder hydrophobic and this property was highly preserved after washing.

Journal of Characterization