Influence of plantation climate and storage time on thermal and viscoelastic properties of natural rubber

Abstract

The Sociedad de Caucho Colombo Argentina (SOCCA) collected natural rubber (NR) from Yarima, Colombia, for seven months spanning two years. The unvulcanized NR was used to conduct a preliminary study, part of a long-term study, to uncover some underlying mechanisms in charge of imparting variation between NR batches, such as the collection site's rainfall conditions and storage period by using calorimetry, rheometry, and a dynamic mechanical analyzer. The ultrasound study found that an increase in monthly rainfall increased the material's elastic constant at 10 MHz, and the crystallization study uncovered that the amount of crystallization decreased with increased rain while remaining relatively constant if rainfall was within the recommended rainfall amount for the tree. Additionally, stress relaxation measurements revealed that an increase in rainfall suggested an increase in the material's temperature sensitivity. The temperature sensitivity relates to the material's processability in which an increase in temperature with high sensitivity will have a more drastic decrease in stress during a relaxation test compared to a material with low sensitivity.

Keywords

• natural rubber
• rainfall
• aging
• rubber production