Dynamic mechanical properties of natural rubber in molten state
สมบัติพลวัตเชิงกลของยางธรรมชาติในสถานะหลอมเหลว
Vilaiporn Luksameevanich, D. of Sci., F. of Sci. and Tech., PSU.
Manus Seadan, Asst. Prof., D. of Sci., F. of Sci. and Tech., PSU.
Arlongkot Wongsuwan, D. of Sci., F. of Sci. and Tech., PSU.
Corresponding e-mail : E-mail : vnoparat@bunga.pn.psu.ac.th
Grant : Government Budget
Published : Research Report
Key words : dynamic mechanical properties, natural rubber, molten state
Dynamic properties of STR5L (grade of natural rubber) and its compounds, mixed with carbon-black and CaCO3 were investigated and tested as a hollow cylinder specimen in shear molde on Dy-namic Mechanical Analyser series 7 (DMA7). Experiments were done at 1% shear strain with static displacement control at the temperature ranged of 80-200oC and the angular frequencies ranged of
0.63-328 rad/s. Master curves of storage and loss modulus, at the reference temperature of 120oC,
were investigated by using time - temperature superposition principle and WLF equation. The master curve of pure natural rubber presents a good plateau of rubber state with its terminal limit, a cross
point of storage and loss modulus at 3x10-2 rad/s. At rubber plateau region, the storage and loss mo-
dulus are 3x105 and 1x105 Pa respectively and at terminal limit these value is about 3x104 Pa. The carbon-black mixed in the compound cause increased in storage and loss modulus at high frequency
and slightly shift the rubber state limit to a higher frequency. The rubber state limit shift about 2 order from pure STR5L or 1 rad/s as the compound having 60 phr of carbon-black content. The affect of CaCO3 on these dynamic properties was increasing only a loss modulus at high frequency and cause a strong shift the rubber state limit; its movement is about 4 order of frequency when the compound having 60 phr of CaCO3.
BACK