Production of polymer-plaster composite by gamma irradiation

The estimated amount of plaster wastes in the construction industry is 45%. The reduction of these wastes is of concern, as the cost of lost material and the waste management can affect the competitiveness of the industry. The blend of plaster with a particular resin generates a composite, which gives the pre-molded obtained from this mixture, special properties. In this case, the plasticity of the plaster generates pre-molded products with wealth of details. Additionally, the use of nuclear techniques for initiation of the polymerization reaction to obtain this type of composite can eliminate the need for a heat source, which is the conventional way to obtain polymerization, considerably reducing the costs of the process. As a function of the availability of styrene monomer, in the initial phase of the research test samples were prepared from plaster composites with this type of material. The test samples, composed of plaster and styrene, were irradiated with a Cs-137 (662 keV) gamma source for a period of time of two days in an air pressurized chamber (total dose of 43.2 kGy). Tests of resistance to compression, tensile strength in bending and water absorption, were based on a type of experimental design, CCRD (Central Composite Rotatable Design). The percent average weight of polymer by weight of the test sample was 14%. The presence of a polymerized resin gives the sample qualities such as being highly impervious to water and having high mechanical strength, allowing its use in the manufacture of different types of materials.

► Gypsum/styrene composites irradiated with Cs-137 (662 keV) gamma-rays.
► Tests of resistance to compression, tensile strength in bending, water absorption.
► Experiment based on a Central Composite Rotatable Design (CCRD).
► Best regions of operational conditions for each factor set identified.
► Final product highly impervious to water and with high mechanical strength.