Characterization and evaluation of vulcanization time for colombian natural rubber from three hevea brasiliensis tree clones

Abstract

Significant projects for natural rubber (NR) production in Colombia have been developed in the past two decades. However, several topics about the properties of colombian NR have not been studied yet. In this work, NR obtained from FX3864, IAN873 and IAN710 rubber tree clones, cultivated in Tarazá-Antioquia-Colombia, is characterized by FTIR, DSC and TGA. Also, a comparison with SGR10 guatemalan rubber and technically specified rubber of Caquetá, Colombia, is carried out. Rubber compounds were manufactured following the same formulation, varying only the type of natural rubber used as matrix. Uncured mixtures were evaluated by vulcanization rheometry at 160 °C, and cylindrical and tension specimens were molded using compression molding. Optimal vulcanization time for each geometry was determinated based on their elastic modulus under  tension  and  uniaxial  compression,  a  methodology  that  can  be  applied  to  commercial  products.  Test  specimens  for  compression-set, density and hardness were moulded using the vulcanization optimal times. Some differences between FTIR spectra, decomposition temperature, rheometric parameters and mechanical properties of the natural rubbers compounds were identified. Some recommendations for Colombian natural rubbers processing are postulated, seeking a better reliability.