Expanded polystyrene Subject

Addition of rubber particles of 30% to 100% by weight to cement with a grain size of approximately 40 to 60 mesh (0.4 to 0.25 mm) will produce a lightweight cement. The addition of rubber particles also creates a low permeability. The compositions are advantageous for cementing zones subjected to extreme dynamic stresses such as perforation zones and the junctions of branches in a multi-sidetrack well. Recycled, expanded polystyrene lowers the density of a hydraulic cement formulation and is an environmentally friendly solution for downcycling waste materials. 

In unconfined pre-expansion the translucent beads grow larger and become white in color. Confined and subjected to heat, the preexpanded beads can produce a smooth-skinned closed-cell foam of controlled density, registering every detail of an intricate mold. To minimize formation of a density gradient and to ensure uniform expansion throughout the molded piece, expandable-polystyrene beads are preexpanded to the approximate required density by control of time and temperature, since the process of molding does not increase the density (6). 

BS 3837, Part 2. describes a method for the determination of the water absorption by diffusion for expanded polystyrene board. This method is based on the Swiss Standard SIA 279, Part 5.07, and involves subjecting the specimen (500 x 500 x. 50mm) to the environment above a small reservoir of water maintained at 50 C with the other side of the foam at 0 C. After 28 days the increase in mass is expressed as the water absorption (Fig. 5). 

The complete TV set is assembled and packed in a standard customer delivery box with expanded polystyrene foam. Random samples of the packages are then subjected to the following tests. 

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