|Year of Publication||2015|
|Authors||เพ็ชญไพศิษฏ์ ช วยากรณ์|
|Series Editor||รวมเจริญ จรีรัตน์|
In this research work, the novel renewable source precursors from modified liquid natural rubber were used to prepare elastomeric polyurethane for metal coating and foam applications. The elastomeric PU for metal coating was synthesized from the modified natural rubber with OH functional group (HLNR), modified NR grafted with polysiloxane (LENR-g-PDMS), commercial polyurethane paint B (PU pack (B)) and modified PET (P-ET-PA and P-T-PA) as a polyol/polyacid, a commercial polyurethane paint A (PU pack (A)) and commercial MDI (Millionate MR-200) as isocyanate. The physical properties as film-thickness, gloss, hardness, adhesion (cross-cut and scratch-adhesion), impact test, erichsen, bending and chemical resistant of the coated film were investigated by following the industrial standard for automobile coating. Salt spray and electrochemical impedance spectroscopy (EIS) were used to examine the corrosion behavior of coated steel. It was found that the best formulas of PU elastomer prepared from PU pack (A) and HLNR are Isocyanate (A) : Polyol (B) : HLNR 50 equal to 10 : 1.5 : 0.75 and 10 : 1.5 : 1 by weight. These coatings showed good physical properties followed the industrial standard for automobile coating and suitable for using in acid and salt condition. Meanwhile, the best formulas of PU elastomer prepared from commercial MDI, PU pack (B), and HLNR is MDI : Polyol (B) : HLNR 35 equal to 0.75 : 0.5 : 0.75 by weight. This coating is suitable for using in basic condition. Furthermore, form the DSC spectra, it was found that film from HLNR showed more heat resistant than those of a two-pack PU topcoat. The film of PU elastomer prepared from PU pack (A), PU pack (B) and HLNR also could be used at higher temperature than that of prepared from MDI, PU pack (B) and HLNR.
Polyurethane foams were prepared from a mixture of polyols (Thamol-HL-456 and HLNR) and pMDI. The aim of this study is to investigate the effect of hydroxyl content of HLNR, the ratio of HLNR and commercial polyols on foaming behaviors and physico-mechanical properties comparing with commercial polyols and standard testing for rigid PU foam. It was found that PUA1 and PUB1 gave the best foaming behavior, cell structure and physical property for rigid PU foam application. Regarding physical properties and mechanical properties of foam, HLNR 22, HLNR 35 HLNR 50 and HLNR 80 with the OH of HLNR in the range of 0.1-0.4, density hardness and compression strength increase with hydroxyl content. The density was found in the range of 43-52 kg/m3 . Hardness in the range of 45-50 shore C and compression strength in the range of 169-318 kPa. Especially, foam from commercial polyols with HLNR 22 (PUA) HLNR 35 (PUB) and HLNR 50 (PUC) showed the suitable physical and mechanical properties. All prepared foam satisfied the standards.
|Alternate Title||Development and Application of Modified Natural Rubber for Polyurethane Production : Coating and Foam|