| 配方类型： |
RUBBER, PLASTICS, WAXES |
| 配方说明： |
Molding Polystyrene Foam |
| 配制方法： |
In the typical cycle, a measured amount of polystyrene beads, depending on the desired density of the foam, is placed in the mold. The mold is closed and heat applied. After the beads have expanded, the mold is cooled, then opened and the article removed.
For products less than one inch thick, the mold is usually heated by hot air or steam. For thicker sections, dry steam (10 to 30 psi) is introduced directly into the cavity of the mold. A temperature of 100 to 135'C is required. The expansion time may range from 10 seconds to 3 minutes for sections 12 inches thick. Internal mold pressures generated during expansion are 10 to 50 psi and proportional to the density of the molded article.
Cooling below 40'C is necessary before taking the article from the mold.
Cooling times range from one to fifteen minutes. Silicone greases are satisfactory mold-releasing agents.
Best materials for molds are brass and bronze. The walls should be at least 1/4 inch thick. The design should allow removal of th |
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