Use of natural rubber in rice huskers

Boontham Nithi-Uthai, D. of Rubber Technology and Polymer Sci., F. of Sci. and Tech., PSU.
Preecha Pongbhai, Asst. Prof., D. of Rubber Tech. and Polymer Sci., F. of Sci. and Tech., PSU.
Pornpun Nithi-Uthai, Assoc. Prof., D. of Rubber Tech. and Polymer Sci., F. of Sci. and Tech., PSU.
Paiboon Inajit, Asst. Prof., D. of Chemical Eng., F. of Eng., PSU.
Orasa Patarapaiboolchai, D. of Rubber Tech. and Polymer Sci., F. of Sci. and Tech., PSU.
Corresponding e-mail : porasa@bunga.pn.psu.ac.th

Grant : STDB (1989-1993)
Published : Research report
Key words : natural rubber, rubber roll, dehusking

Rubber roll for dehusking rice should have hardness between 80-95 IRHD. The most suitable hardness is 88 IRHD. Roller with hardness less than 80 IRHD cannot remove husk from paddy rice but it will rapidly wear itself. In compounding rubber roller, though carbon black is the best reinforc-ing filler for tire and other mechanical goods, it cannot be used in making rubber roller. Roller with carbon black as a filler will cause gray color to finish mill rice. Thus hydrated precipitated silica is normal filler use in normal compounding.

Natural rubber can make rubber roller as good as nitrile rubber providing of using silane with silica. However, this type of natural rubber roller is only slightly cheaper than those roller made from nitrile rubber. Most of rubber rollers showed hardness drop rapidly during milling. Those roller made from natural rubber had hardness drop between 8-9 IRHD and some roller had hardness finally only around 80 IRHD. But those roller made from nitrile rubber had hardness drop between 3-8 IRHD. None of nitrile roller had final hardness of less than 86 IRHD. It is proposed that, if natural rubber roller, with suitable modification on rubber backbone, is made to high hardness and without hardness loss during using, then one can get a very good rubber roller from natural rubber.

---

BACK