Ageing of natural rubber under stress

Ageing of Natural Rubber under Stress

We report a dynamical-mechanical study of stress relaxation at small deformation in a natural (polyisoprene) rubber well above its glass transition temperature Tg. We find that an almost complete relaxation of stress takes place over very long relaxation periods, even though the elastic network is retained. The relaxation rate and the long-time equilibrium modulus are sensitive functions of tem...

The Cyclization of Natural Rubber

The effects of solvent, temperature, time, weight percent of catalyst on the rate and mechanism of cyclization of natural rubber (NR) was studied in toluene and xylene solutions having tin tetra chloride catalyst (SnCl4). Iodometric titration show, with 8% SnCl4 (based on polymer weight) cyclization occurs, leaving 27.4% of the total unsaturation. Infrared spectra of c...

Multiaxial stress effects on fatigue behavior of filled natural rubber

This work explores multiaxial stress effects on fatigue crack nucleation and growth in filled natural rubber based on experiments using short thin-walled cylindrical specimens subjected to axial and twist displacements. Cyclic stress–strain response exhibits significant initial softening relative to the monotonic response, followed by a more gradual additional softening. Irreversible breakage o...

Natural Rubber Latex Allergy

Natural rubber latex allergy.

Immediate hypersensitivity to natural rubber latex (NRL) has become increasingly common during the last 20 years. It is currently one of the most frequently encountered occupational diseases among the healthcare workers and a problem even in other occupations where protective gloves are used. Several groups at high risk for developing NRL allergy have been defined, including healthcare workers ...