Experimental study of the effects of different drying methods on the kinetics and quality of air dried sheet (ADS) rubber

Rubber (Hevea brasiliensis) is the most important commercial natural source in ASEAN countries. Mostly natural rubber (NR) industries were followed by old traditional method. However, understanding in the rubber drying process occurred. Then, this research aims to study effect drying conditions on kinetics and quality of air dried sheet (ADS) rubber. The five different drying strategies were carried on by green house drying (GH), green house and natural convention (GH-NC) drying, open sun and natural convention (OS-NC) drying, infrared radiation (IR) drying and hot air (HA) drying. Initial moisture content of fresh rubber sheet was varied between 30 and 50% dry-basis and dried samples had final moisture content of 0.5% dry-basis. From the experiments, it was found that falling drying rate stages and mathematical models of Approximation of diffusion model can predict the behavior of ADS rubber was good. ADS rubber was dried by GH-NC drying longer period than those of OS-NC drying, GH drying, HA drying and IR drying, respectively. Additionally, drying at a low drying temperature has a low specific energy consumption compared to those drying of high temperature. To determine qualities following the highest standard Thai rubber (STR5L) grade, the results showed that quality of samples was acceptable in market level.