منابع مشابه
Aging of Rigid Polyurethane Foams: Thermal Conductivity of N2 and Cyclopentane Gas Mixtures
The thermal conductivity of three mixtures of nitrogen and cyclopentane is measured using a transient hot wire method, at temperatures between 315.14 and 395.89K, and pressures up to 0.53MPa. These mixtures are important in the evaluation of the evolution of the thermal insulation capacity of closed-cell polyurethane foams considering their aging during the respective applications’ total life t...
متن کاملThe influence of environmental aging upon the loadbearing properties of polyurethane foams.
The effects of environmental exposure upon the loadbearing properties of nine polyurethane foams commonly used for wheelchair cushion construction were studied. Test pieces with and without a stretch cloth cover were aged in the open air at Houston over the period April 26 to October 31, 1982. The indentation resistance of each piece was measured initially and at frequent intervals during the e...
متن کاملThe Modification of Polyurethane Foams Using New Boroorganic Polyols (II) Polyurethane Foams from Boron-Modified Hydroxypropyl Urea Derivatives
The work focuses on research related to determination of application possibility of new, ecofriendly boroorganic polyols in rigid polyurethane foams production. Polyols were obtained from hydroxypropyl urea derivatives esterified with boric acid and propylene carbonate. The influence of esterification type on properties of polyols and next on polyurethane foams properties was determined. Nitrog...
متن کاملElimination of Amine Emissions from Polyurethane Foams: Challenges and Opportunities
Polyurethanes are a unique class of plastic in the sense that independent manufacturers buy liquid polyols and isocyanates and then react them in the presence of catalysts, surfactants and other additives in widely varying processing schemes to make the final commercial product. In some manufacturing scenarios, there is a growing concern about worker exposure to volatile organic chemicals (VOC)...
متن کاملEffects of silicon surfactant in rigid polyurethane foams
The rigid polyurethane foams (RPUFs) have been fabricated from high functional crude 4,4’-di-phenylmethane diisocyanate (CMDI) and polypropylene glycols (PPGs) for a wide range of surfactant concentration with an environmently friendly blowing agent (HFC 365mfc). Cream time, gel time, and tack-free time increased with the addition of surfactant. Foam density decreased rapidly to a minimum at 0....
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ژورنال
عنوان ژورنال: International Journal of Heat and Mass Transfer
سال: 1986
ISSN: 0017-9310
DOI: 10.1016/0017-9310(86)90148-1