Rheological properties for polymer blends of natural rubber and cassava starch

Rheological properties for polymer blends of natural rubber and cassava starch
การวัดสมบัติการไหลของพอลิเมอร์เบลนด์ของยางธรรมชาติและแป้งมันสำปะหลัง

Charoen Nakason, Asst. Prof., D. of Rubber Tech. and Polymer Sci., F. of Sci. and Tech., PSU.
Azizon Kaesaman, D. of Rubber Tech. and Polymer Sci., F. of Sci. and Tech., PSU.
Tinarat Wongkul, B.Sc. Student in Rubber Tech., PSU.
Suda Kiatkamjonwong, D. of Photographic Sci. and Printing Tech., F. of Sci., Chulalongkorn U., Bangkok
Corresponding e-mail : ncharoen@bunga.pn.psu.ac.th

Grant : Thailand Research Fund
Presented : International Symposium on The Challenges of Polymer Science and Technology in the 21st Century, in 26th Congress on Science and Technology of Thailand, Queen Sirikit Convention Center, Bangkok, 18-20 October 2000, p. 722
Key words : epoxidized natural rubber, cassava starch, rheological properties, compatibiliser

Epoxidized natural rubber (ENR) was used as a blending ingredient and a compatibilizer for blending of natural rubber (STR5L) and cassava starch. Rheological properties in terms of shear stress and shear viscosity were plotted against shear rate. The results showed that pure ENR gave lower values than that of the blends of ENR with the starch. Moreover, both shear stress and shear viscosity increased with increasing with amount of starch. Comparison of shear stress and shear rate, at the same level of cassava starch, the blends of ENR showed the highest values, while the blends of STR5L with a compatibiliser showed the lower values than that of the first type of rubber blend but higher than the values for the blends of STR5L. This may be attributed to the polar nature of epoxide ring present in the ENR molecules. Chemical bond between the polar group of ENR and hydroxyl groups in the cassava starch molecules was established. For the blends of STR5L with ENR as an compati-bilizer, chemical bonding between polar groups in the ENR molecules and starch molecules was also formed, while the non-polar parts of ENR molecules compatibilized to the natural rubber molecules.

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