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CURE AND MECHANICAL PROPERTIES OF CARBOXYLATED NITRILE RUBBER (XNBR) VULCANIZED BY ALKALINE EARTH METAL COMPOUNDS

Tulyapitak, Tulyapong
http://rave.ohiolink.edu/etdc/view?acc_num=akron1158067153

Abstract Details

2006, Doctor of Philosophy, University of Akron, Polymer Science.
Compounds of carboxylated nitrile rubber (XNBR) with alkaline metal oxides and hydroxide were prepared, and their cure and mechanical properties were investigated. Magnesium oxide (MgO) with different specific surface areas (45, 65, and 140 m2/g) was used. Increased specific surface area and concentration of MgO resulted in higher cure rate. Optimum stiffness, tensile strength, and ultimate strain required an equimolar amount of acidity and MgO. The effect of specific surface area on tensile properties was not significant. Crosslink density of XNBR-MgO vulcanizates increased with increased amounts of MgO. ATR-IR spectroscopy showed that neutralization occurs in two steps: (1) During mixing and storage, MgO reacts with carboxyl groups (RCOOH) to give RCOOMgOH. (2) Upon curing, these react bimolecularly to form RCOOMgOOCR and Mg(OH)2. Dynamic mechanical thermal analysis revealed an ionic transition at higher temperature, in addition to the glass transition. The ionic transition shifts to higher temperature with increasing MgO concentration. Like MgO-XNBR systems, cure rates of XNBR-calcium hydroxide (Ca(OH)2) and XNBR-barium oxide (BaO) compounds increased with increased content of curing agents. Curing by these two agents resulted in ionic crosslinks. To ensure optimum tensile properties, equimolar amounts of carboxyl groups and curing agents were required. Dynamic mechanical analysis revealed the ionic transition in these two systems. It shifted to higher temperature with increased amounts of curing agents. In contrast to MgO, Ca(OH)2, and BaO, calcium oxide (CaO) gave results similar to those for thermally cured samples. No ionic transition was observed in XNBR-CaO systems. Tensile strength of XNBR depended on the strength of ionic crosslinks, which was dependent on the size of the alkaline metal ions.
Gary Hamed (Advisor)
222 p.
Chemistry, Polymer
carboxylated nitrile rubber; XNBR; calcium oxide; magnesium oxide; barium oxide; calcium hydroxide

Recommended Citations

Citations

  • Tulyapitak, T. (2006). CURE AND MECHANICAL PROPERTIES OF CARBOXYLATED NITRILE RUBBER (XNBR) VULCANIZED BY ALKALINE EARTH METAL COMPOUNDS [Doctoral dissertation, University of Akron]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=akron1158067153

    APA Style (7th edition)

  • Tulyapitak, Tulyapong. CURE AND MECHANICAL PROPERTIES OF CARBOXYLATED NITRILE RUBBER (XNBR) VULCANIZED BY ALKALINE EARTH METAL COMPOUNDS. 2006. University of Akron, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=akron1158067153.

    MLA Style (8th edition)

  • Tulyapitak, Tulyapong. "CURE AND MECHANICAL PROPERTIES OF CARBOXYLATED NITRILE RUBBER (XNBR) VULCANIZED BY ALKALINE EARTH METAL COMPOUNDS." Doctoral dissertation, University of Akron, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=akron1158067153

    Chicago Manual of Style (17th edition)

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