Abstract
Polyurethane foams are currently the most effective thermal insulation materials, polyisocyanurates have low combustibility. Predicting the number of closed cells forming a gas-filled matrix in the finished polymer is necessary to improve the quality and durability of rigid sprayed polyurethane foam (SPF) and also be able to determine their quantity in finished coatings using standardized techniques. Depending on the number of closed cells, the polyurethane coatings are classified into certain levels in European documents. The methods of determining the volume percentage of open and closed cells of polyurethane foam, the problems of applying these methods, measuring equipment and their errors are analyzed in the article. The authors analyzed the international standard ISO 4590 for determining the volume percentage of open and closed cells spread in the EU countries and the American standard ASTM D 6226 for the purposes of harmonization of European standards with the developed national standard for PUR insulation and polyisocyanurate (PIR), sprayed on the site of production.
Highlights
In Russia, for rigid sprayed polyurethane foam, two national standards are being developed, one of which is GOST R "Thermal insulation coating of polyurethane foam (PUR) and polyisocyanurate foam (PIR), sprayed on the site of p roduction
To improve the quality and durability of rigid sprayed polyurethane foam (SPF) and the overall understanding of the provision of most technological characteristics, it is necessary to predict the number of closed cells forming a gas-filled matrix in the finished polymer, be able to determine their quantity in finished coatings, using standardized methods [1]
Methods of accelerated aging, specified in subparagraphs C.4 and C.5 in EN 14315-1 are primarily developed for PUR/PIR products with closed cell content of greater than or equal to 90% and which are manufactured using high molecular weight blowing agents such as HFC 134a, 245fa, 227ea, 365mfc, which remain in the cells of the coating during the period specified by the manufacturer and more [1]
Summary
In Russia, for rigid sprayed polyurethane foam, two national standards are being developed, one of which is GOST R "Thermal insulation coating of polyurethane foam (PUR) and polyisocyanurate foam (PIR), sprayed on the site of p roduction. For products of class CCC4, since the value of thermal conductivity after aging depends strongly on the thickness of the product, and whether there is any diffusion-preventing finish in the final application of the product, it is necessary to indicate the thermal resistance according to the thic kness under three special conditions with respect to any surfaces that prevent diffusion. In the American standards for rigid polyurethane foam, the classification according to the percentage of closed cells is absent, this parameter is given as one of the physical propert ies (see Chapter 3 of this NTO)
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