Polyurethane foams blown with various types of environmentally friendly blowing agents

Abstract

Three different types of environmently friendly blowing agents (HFC 365mfc, HFC 245fa and water) have been used to fabricate rigid polyurethane foams from crude methylene diphenyl diisocyanate and polypropylene glycols. Water induced the earliest bubble, temperature and pressure rises, whereas HFC 365mfc gave the slowest reactivity. Water blown foams showed the largest cell and the lowest density and compression strength, together with the highest glass transition temperature and the greatest dimensional stalibility at high temperature. With the combined effects of large cell and large thermal conductivity of CO 2 , water blown foam gave the highest conductivity of the foam. On the other hand, HFC 365mfc gave the smallest cell size, the greatest foam density and compression strength, whereas HFC 245fa gave the intermediate values, except the lowest thermal conductivity of the foam.

Polyurethane Foams for Thermal Insulation Uses Produced from Castor Oil and Crude Glycerol Biopolyols

“…The effect of the blowing agent type on the apparent density of the foams produced from GCo polyols ( Table 2 ) showed that the formulations with physical blowing agents (cyclopentane and n-pentane) produced foams with higher densities than those synthesized with the chemical blowing agent (water). Similar results have been reported in the literature [ 32 , 33 , 34 ], and this behaviour indicates that smaller cells are formed due to the rapid volatilization of physical blowing agents, which have a low boiling point, during the highly exothermic foam growth step in comparison with the CO 2 , produced by the reaction of water with isocyanate [ 35 ].…”

Rigid polyurethane foams incorporated with phase change materials: A state-of-the-art review and future research pathways

“…Being an excellent thermal insulating material, rigid polyurethane foam (RPUF) has been widely used in the field of thermal insulation in building envelopes to save energy due to their M a n u s c r i p t low thermal conductivity, superior specific mechanical properties and low density [3][4]. As traditional blowing agents, CFCs and HCFCs have been phased out in developed countries and will be totally banned by 2020 in developing countries according to the Montreal protocol, which led to an important research focus on foam synthesis modification using HFC-245fa, HFC-365mfc, cyclopentane and water as new generation of blowing agents [5][6][7][8]. Owing to the inherent drawbacks in these environmentally friendly blowing agents, the mechanical and thermal performance of the new generation of foam products are not as good as traditional foams.…”

Synthesis of Polyurethane Foam Considering Mixture Blowing Agents for Application to Cryogenic Environments

“…Currently, polyurethane foam produced using water‐blown methods has the most similar properties to gas‐blown polyurethane foam. Nevertheless, the thermal performance of water‐blown polyurethane foam is significantly lesser owing to the higher thermal conductivity of CO 2 compared to other gases . In water‐blown polyurethane foam, water reacts with isocyanate and polyol and generates CO 2 gas.…”