Study on Strain-Induced Crystallization of Natural Rubbers from Guayule and Rubber Dandelion

ワユーレ天然ゴムとタンポポ天然ゴムの伸長結晶化に関する研究

2017-09-25

2017-09-25

Because of the biosecurity and biodiversity problems of natural rubber (NR) from Hevea brasiliensis, studies on other rubber yielding plants, i.e., guayule and rubber dandelion have been focused. Strain-induced crystallization (SIC) has been well known as an indispensable function for Hevea NR. In order to determine their suitability as alternatives to Hevea NR, characteristics of SIC for sulfur crosslinked guayule and dandelion NRs were investigated using quick in situ simultaneous synchrotron time-resolved wide-angle X-ray diffraction/tensile measurements for the first time in this study. By comparing with sulfur cross-linked Hevea NR, the SIC of cross-linked dandelion NR was comparable to that of cross-linked Hevea NR. However, cross-linked guayule NR showed a superior SIC upon high stretching to cross-linked dandelion and Hevea NRs. This were presumably due to the lower non-rubber components particularly a lack of proteins leading the less branched physical network structure in guayule NR, compared to other NRs. In addition, a comparative SIC study between cross-linked guayule NR and isoprene rubber suggested that non-rubber components in guayule NR, which formed additional cross-linked sites and its high regularity of cis-1,4-polyisoprene configuration accelerated the SIC of cross-linked guayule NR. From the new points of view of SIC, the roles of non-rubber components on characteristic SIC of cross-linked guayule and dandelion NRs were apparently detected, probably relating to the different aggregation degrees of non-rubber components between the NRs. The results of DMA and Mullins effect also supported this hypothesis. Interestingly, the higher-order structures of their physically aggregated non-rubber components were possibly proposed. The present observation in this study confirmed that both guayule and dandelion NRs are useful as alternatives of Hevea NR from the view point of SIC features. Nonetheless, the roles of physically aggregated non-rubber components must be taken into account as they are applied to rubber materials.

博士（工学）

京都工芸繊維大学

14303甲第841号

http://hdl.handle.net/10212/2417

eng

none

Thesis or Dissertation

Thesis