ISSN:
1662-9752
Source:
Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
Topics:
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
Notes:
Molded polyurethane foams for car seats are based on petrochemical polyols ofmolecular weight 4000-6000 and copolymer polyols containing micron size polymeric particles.Copolymer polyols (CPP) typically constitute 30% of the mixture with the base polyol. They helpcell opening, increase load bearing and tear strength of the foams, but they are relatively expensive.Hyperbranched polyols of petrochemical origin were used in molded foams.[1] They are solid inthe pure form and due to high crosslinking density could be incorporated at low concentration inconjunction with copolymer polyols. Instead, we have made hyperbranched polyols which could bea total replacement for CPP in molded foams. Six hyperbranched polyols with primary andsecondary hydroxyl groups and different hydroxyl numbers were prepared from soybean oil andtested in flexible foams. Novel polyols were liquid even at very high molecular weights and couldcompletely replace copolymer polyols. Functionality of these polyols increased linearly withmolecular weight to very high values, resulting eventually in their high crosslinking power. Theeffects of the type of hydroxyl groups (primary vs. secondary), hydroxyl number (from 85 to 135mg KOH/g), and concentration (7.5-30%) in the mixture with the base polyol on foam propertieswere analyzed. It was found that hyperbranched polyols could replace copolymer polyolscompletely but their effect on cell morphology and mechanical properties varied with the type ofpolyol and concentration
Type of Medium:
Electronic Resource
URL:
http://www.tib-hannover.de/fulltexts/2011/0528/02/17/transtech_doi~10.4028%252Fwww.scientific.net%252FMSF.555.459.pdf
