Natural Rubber Prepared by the Fast Rubber Sheet-Forming Method

Natural rubber (NR) with structural integrity was prepared by the Fast Rubber Sheet-Forming (FRSF) method for the first time, using NR latex derived from Para rubber tree (Hevea brasiliensis). NR was prepared by spraying the NR latex onto preheated metallic surfaces at various drying temperatures of 140, 150, 160, and 170 °C for short times, a minute or less, and then it was collected as a sheet. The water and gel contents of NR were measured, while the structure of NR was characterized by solution-state 1H, 13C NMR, and FTIR spectroscopies. The results showed that NR prepared by the FRSF method contained little amount of water, while its gel content was comparable to that of NR dried in an oven at 50 °C under atmospheric condition. The oxidative degradation, epoxidation, and cis–trans isomerization were suppressed when NR was prepared by the FRSF method, based on the results of 1H, 13C NMR, and FTIR measurements. NR prepared by the FRSF method was superior in mechanical properties to NR dried in an oven at 50 °C since the structural integrity of NR facilitated the rapid strain-induced crystallization due to a long sequence of cis-1,4-isoprene units.