Dependence of physical properties on composition in a series of high load-bearing polyurethane foams. Part II. Effects of variations in reactant ratios

✍ Scribed by Morris A. Mendelsohn; Richard G. Black; Robert H. Runk; Herbert F. Minter

• Publisher: John Wiley and Sons
• Year: 1966
• Tongue: English
• Weight: 845 KB
• Volume: 10
• Category: Article
• ISSN: 0021-8995
• DOI: 10.1002/app.1966.070100309

✦ Synopsis

Data and interpretations are presented on the effects of chemical variations on the physical properties, and in particular, the compression-deflection characteristics of a series of high load-bearing, open-celled, shock-mitigating polyurethane foams. The load-bearing capability of the foam is considered to be a function of density and intrinsic st,iffness of the polymer. Polyol components of the formulations consisted of a poly-(oxypropylene triol) of approximately 4000 molectilar weight and ethylene glycol. The blowing agents were water and trimerized linseed fatty acids. A solntion of polymethylene polyphenylisocyanate and tolylene diisocyanat,e comprised the isocyanate mixture. Stannous octoate and N-ethylmorpholine were the diial catalysts. Load-bearing capability of the foam was raised by increasing the concentrations of the isocyanates, poly-(oxypropylene t,riol), stannous octoate, and by employing higher ratios of polymethylene polyphenylisocyanate to tolylene diisocyanate. Decrease in compressive strength resulted from increasing the quantity of blowing agents and N-ethylmorpholine. Increasing the quantity of ethylene glycol gave load-bearing properties which increased to a maximum and then decreased. Chemical variations are analyzed in t,erms of t.heir effects on the properties of the polymeric networks. These include crosslink density, number and distribiition of hydrogen bonds, chain orienhtion and mobility, and relative selertivity of the varioiis reactions. Effects on the overall hnlk properties of i.he foam w e disciissed in terms of the chemical composition.