Proper conditions for curing the cup lump that affect to the properties of natural rubber mixed with synthetic rubber properties Falida Sriprom* Supawadee Theerathammakorn and Preeprem tassanakun

Abstract

            The objective of this research is to study the curing time that makes the moisture content of rubber lump suitable for the production of natural rubber mixed with synthetic rubber (MNR) and has the properties as specified, the effect of relative humidity that influences the moisture content of rubber lump and dry rubber content, which affected the amount of waste in the production process.
          The research has been carried out, starting with the study of the amount of dry rubber content, relative humidity, and properties of cup lump and MNR rubber. Cup lumps were cured by place at ventilated and plastic covered area and then compare the data to find the best properties.
          It was found that the plastic - covered curing gave the best dry rubber content at 68.51 percent. At the position at the bottom of the pond the moisture content of the cup lump was 31.49 percent, at the average relative humidity of 93 percent at 05.00 AM. The properties of the cup lump cured with plastic covering at the position at the bottom of the pond at 05.00 AM, the initial plasticity of the rubber was the best 45.7 and the plasticity retention index of the rubber was 68.2 as according to the specified standard. The MNR rubber production process by cup lump at the end position has meet the company specified criteria which is based on Standards Thai Rubber and currently can reduce waste to 0.63% with reducing the amount of waste up to 1%.