Hydroxyurethane modifiers

In many cases the use of epoxy materials in so-called field conditions (for industrial, construction sites, etc.) demand an increase in the reaction velocity, which is usually achieved by adding accelerators. At present, the widely used accelerators include alkyl-substituted phenols, benzyl alcohol, carboxylic acids (in particular, salicylic acid), and others. A major disadvantage of these accelerators is their tendency to migrate from the cured epoxy matrix during the exploitation, which could lead to a change in the physical properties of the polymer. They also act as a plasticizer of epoxy-based polymers, and as a result reduce the polymer s chemical resistance. Thus, there is a need for new accelerator-modifiers that can provide faster curing of epoxy-amine compositions without negative side effects, and also improve the properties of the finished product. 

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A novel concept for generating new multifunctional modifiers was developed [26], Hydroxyurethane modifiers (HUMs), which possess a wide range of hydrogen bonds, are embedded in an epoxy polymer network without a direct chemical interaction. Some new hybrid materials obtained by introducing hydroxyalkyl urethane into the polymer network structure, without any additional chemical reactions, are described in the following sections. 

SCHEME 4.5 The process of HUM preparation. (Reprinted from O. Figovsky, O. Birukov, L. Shapovalov, and A. Leykin, Hydroxyurethane Modifier as Effective Additive for Epoxy Matrix, Scientific Israel Technological Advantages 13, no. 4 (2011) 122-128. With permission.)... 

The company Polymate Ltd-INRC (Israel) has developed a number of new two-component flooring and coating compositions based on hybrid nonisocyanate polyurethanes using hydroxyurethane modifiers. Properties of the new materials are presented in Table 4.16 [5,37,38],... 

Novel hydroxyurethane modifiers (HUM) for cold-cured epoxy composite materials were synthesized. It is established that the compositions with HUM demonstrate a significant increase in the speed of the curing process, a nontrivial increase in abrasion resistance, and a marked improvement in strength properties. The HUM, which possesses a wide range of hydrogen bonds, is embedded in an epoxy polymer network without a direct chemical interaction. 

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