|題名: ||The Study of Some Modified Polyurethane Elastomers|
|作者: ||Chen, Wen - Pin;Chen, Kuang-Jung;Chen, Kan-Nan|
|上傳時間: ||2014-01-21 11:30:29 (UTC+8)|
|摘要: ||Some known polyurethane (PU) elast6mers prepared from polyester polyols based on toluene diisocyanate(TDI) have better mechanical properties, especially at higher operating temperature and lower hystersis characteristics, than elastomers derived from polyether polyols based on TDI. However, elastomers from polyether polyols based on TDI have better hydrolytic stability and low temperature properties than those from polyester polyols.
The desirable PU properties may be obtained from some selected polyester polyols-polyether polyols blends which are mutually compatible and become permanently homogeneous and stable mixtures. Howev.e r, the r.eaction of diisocyanate with . incompatible mixture of polyester polyols-polyether polyols invariably yields heterogeneous PU prepolymer systems which become phase separated on standing .
The featured PU properties balanced by both prepolymers derived from polyester po~yols and polyether polyols would be of definite interest. Therefore, the preparations of polyester polyols, polyether-ester polyols, and the PU elastomers derived from both polyester polyols and polyether-ester polyols become our main interests.
Polyester polyols were prepared from the reactioris of adipi c acid with . different mixture of glycols (e . g . , ethylene glycol, propylene glycol, and neopentyl glycol) and the reaction conditions were carried out below 2300C and under ni trogen atmosphere throughout the' react ion. And applied vacuum to drive the , reaction to completion.Polyether-ester polyols could be obtained by the traditional polyesterification process mentioned above. Polyethers (e,g., polyethylene glycols: PEG 400, triethylene glycol, diethylene glycol; poly propylene glycols: PPG 400, and PPG 1000) and adipic acid were used according to the calculated quantities in order to make the molecular weight of the polyether~ster polyols to about 2000. The finished polymers were capped with ethylene glycol. The polyesterification processes with and without catalyst (e.g., hydrochloric acid or phosphoric acid) systems were studied and the reaction kinetics of ' those prepared polyester polyols or polyether-ester polyols with TDI were carried out under normal reaction conditions (at 80-90oC). And the corresponding PU prepolymers were obtained. The viscosity, the aging stability, the effect of polyesterification catalysts, ,and the stabi lizers were taken into consideration.
The PU elastomers were obtained from two different curing systems (MOCA Qr l,A-butandiol). The thermal properties of those cured PU elastomers were carried out by DTA, DSC and thermogravimetry. The detailed procedures of polyester polyols, polyetherester polyols, PU elastomers, preparations and their related, physical properties will be discussed.
|關聯: ||第五屆高分子研討會=5th Annual polymer symposium|