Structural Study Of Epoxidized Natural Rubber (ENR-50) And Its Derivatives Synthesized Via Epoxide Ring-Opening Reactions Using Nmr Techniques
| dc.contributor.author | Hamzah, Rosniza | |
| dc.date.accessioned | 2017-01-09T07:09:09Z | |
| dc.date.available | 2017-01-09T07:09:09Z | |
| dc.date.issued | 2015-06 | |
| dc.description.abstract | A cyclic dithiocarbonate derivatives of epoxidized natural rubber (ENR-50) and three types of hybrids comprising ENR-50/titania (TiO2), ENR-50/zirconia (ZrO2) and ENR-50/tin (Sn) complex were prepared. FTIR, 1D NMR; 1H-, 13C-, 119Sn-NMR, 2D NMR; HMQC, HMBC, COSY, TGA, DSC, TEM, SEM-EDX and XRD techniques were used to characterize the ENR derivative and hybrids. A triad sequence of ENR-50 was successfully assigned using NMR techniques consolidated by the cyclic dithiocarbonate derivative of ENR-50. A cyclic dithiocarbonate derivative of ENR-50 was synthesized from the reaction of purified ENR-50 with carbon disulfide (CS2), in the presence of 4-dimethylaminopyridine (DMAP) as catalyst at reflux temperature (47 °C) for 3 hours. Both ENR/TiO2 and ENR/ZrO2 hybrids were prepared from epoxide ring opening reaction of ENR-50 at mild acidic (acid treated ENR-50) and basic (base treated ENR-50) conditions which later reacted with the respective precursors via sol-gel technique at reflux temperature (60 °C) for 24 hours. The respective source of TiO2 and ZrO2 precursors used were Ti(OCH2CH2CH3)4 and Zr(OCH2CH2CH3)4. The ring opened reaction of ENR-50 with acid and base treated ENR-50 were carried out using acetic acid and potassium hydroxide/isopropanol respectively at reflux temperature (110 °C) for 3 hours. 1H-NMR revealed that 19.56 and 16.76% of epoxide were ring opened from the total amount of the epoxide unit in ENR-50 for acid and base treated ENR-50 respectively and these were supported by quantitative FTIR spectroscopy. The alkyl (R) attachment occured at both most (↑) and least (↓) hindered carbons of the epoxide. 13C- NMR provides the location of R in the polymer chain via additional acetate and ester peaks for acid treated ENR-50 and ether peaks for base treated ENR-50. The Tg value of acid treated ENR-50 was higher than base treated ENR-50 due to extent of ring opening and location of R attachment. The formation of ENR/TiO2 and ENR/ZrO2 hybrids was via C-O-Ti and C-O-Zr networks respectively. Ti atom was specifically tailored at the quaternary carbon E6 while Zr atom as at both (↑) and (↓) carbon (E6 and E7) of the ring opened epoxide. The structural position of R, Ti and Zr were proven using 13C-NMR and 2D NMR. The Tg value of ENR/TiO2 was higher than ENR/ZrO2 hybrid due to types of inorganic moiety. The ENR/Sn complex hybrid was synthesized upon further reaction of ENR/SnCl2.2H2O composite at reflux temperature (110 °C) for 3 hours and upon cooling, the reaction mixture was subject to 1 to 5 hours of CO2 gas treatment. The formation was through various stages of electrophilic attack and finally rearranged to ENR/Sn complex hybrid. The formation of C-O-Sn also occurred at quaternary carbon E6 of ring opened ENR-50. | en_US |
| dc.identifier.uri | http://hdl.handle.net/123456789/3360 | |
| dc.subject | Chemistry | en_US |
| dc.subject | Epoxy compounds | en_US |
| dc.title | Structural Study Of Epoxidized Natural Rubber (ENR-50) And Its Derivatives Synthesized Via Epoxide Ring-Opening Reactions Using Nmr Techniques | en_US |
| dc.type | Thesis | en_US |
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