With Wax-Like Additives

The systems with styrene evaporation suppressants work well only if the surface of the processed UPR is left imdisturbed, allowing the waxy barrier fihn to be formed and stay intact. As soon as laminators start working on the item, the anti-emission fihn is broken and becomes ineffective. 

In a general approach the styrene evaporation suppressants are dissolved in the UPRs. It is soluble in the resin, i.e., in the solution of imsaturated polyester in styrene and in styrene itself as well. It is, however, insoluble in the polyester. In the course of processing, styrene monomer evaporates from the surface and the suppressant forms a thin film, which exhibits barrier properties in relation to styrene. This mechanism is well known as far as solution of paraffin wax in UPRs is concerned. Nevertheless, paraffin wax cannot be applied as a styrene evaporation suppressant because of its antiadhesive properties and the decrease in interlaminar adhesion in glass fiber reinforced UPRs. Thus, a suitable styrene evaporation suppressant should contain an adhesion promotor with a waxy consistence. 

The general properties of a commercial styrene evaporation suppressant are presented in an article [97]. The evaporation efficiency of that suppressant was determined. The laboratory determination of the evaporation is carried out by weighing the UPR before and after the weight loss in an air stream. The effect of temperature and air stream rate on the evaporation was investigated [98]. 

Since commercialization in the mid 1980s by Byk-Chemie of the styrene evaporation suppressant BYK S 740 which was elaborated at the Industrial Chemistry Research Institute in Warsaw, Poland, some new information about low styrene-emission (LSE) UPRs was launched, cf., e.g., refs. [100,101]. 

Styrene has been classifled as a possible carcinogen. Thus, an operatively simple method was needed to determine the styrene concentration in air which the workers busy with laminating are occupationally exposed to. The elaborated method of analysis consists of a diffusive sampler, which can be analyzed using thermal desorption-gas chromatography, and is apphed for styrene absorption from the ambient environment [102]. 

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