Chemical-physical properties and antimicrobial efficacy of neem oil-based waterborne polyurethanes

• Main Authors: Chieh-An Tsai, 蔡捷安
• Other Authors: 陳奕君
• Format: Others
• Language: zh-TW
• Published: 2017
• Online Access: http://ndltd.ncl.edu.tw/handle/98431486032391213761

碩士 === 國立中興大學 === 森林學系所 === 105 === In this study, waterborne polyurethane (PU) resins were synthesized by reacting isophorone diisocyanate (IPDI) with polytetramethylene ether glycol (PTMG). The micronized emulsion of neem oil was prepared with the surfactant of Tween 80. In the first topic of this thesis, the effects of various neem oil/waterborne PU resins weight ratio on the waterborne PU solutions and films were studied. Secondly, the neem oil glyceride (NOG) was synthesized by a transesterification process. The NOG was used as polyol and replace partial PTMG. The effects of various PTMG/NOG molar ratios on the waterborne PU solutions, films and coatings were evaluated. Furthermore, neem oil was contained various bacteriostatic components and the antimicrobial efficacy of waterborne PU films synthesized with various PTMG/NOG molar ratios was investigated. The results showed that the micronized neem oil was prepared with 1/1 weight ratio of neem oil/Tween 80 had smaller micelles, narrower particle size distribution, and better stability than theirs of other weight ratio. With neem oil/waterborne PU resins weight ratio increasing, the weight retention of water resistance, surface hydrophilicity, elongation at break, and thermal stability of waterborne PU films increase while the weight retention of solvent resistance, tensile strength and Young''s modulus decrease. Waterborne PU resins were successfully synthesized with various PTMG/NOG molar ratios. With the content of NOG increasing, the pH, viscosity, and particle size of waterborne PU solutions increase. The films with PTMG/NOG molar ratio of 75/25, 50/50, and 25/75 were intact. On the other hands, film with PTMG/NOG molar ratio of 0/100 was broken brittle after preparation process. The weight retention of water resistance and solvent resistance of waterborne PU films with NOG was higher than 94.9% and 88.2%, respectively. With the content of NOG increasing, the Young''s modulus and ultraviolet (UV) absorption of waterborne PU films increase. However, the elongation at break and thermal stability decrease. Waterborne PU coating with various PTMG/NOG molar ratios showed good performance of adhesion and durability for wood. With the content of NOG increasing, the hardness of waterborne PU coatings increases. Nevertheless, the impact resistance and abrasion resistance decrease. NOG based waterborne PU coatings exhibited poor chemical resistance to 50% ethanol and acetone. Neem oil showed antimicrobial activity against E. coli and S. aureus. NOG based waterborne PU films exhibited contact killing activity against E. coli and S. aureus. With the content of micronized neem oil increasing, the antimicrobial efficacy of waterborne PU films containing NOG blending with micronized neem oil increases.