High-Performance Cooling Screws

High-performance screw with bimetallic lined cylinder designed for processing a specific plastic can be cored for cooling. 

Time, pressure, and temperature controls indicate whether the performance requirements of a molded product are being met. The time factors include the rate of injection, duration of ram pressure, time of cooling, time of piastication, and screw RPM. Pressure requirement factors relate to injection high and low pressure cycles, back pressure on the extruder screw, and pressure loss before the plastic enters the cavity which can be caused by a variety of restrictions in the mold. The temperature control factors are in the mold (cavity and core), barrel, and nozzle, as well as the melt temperature from back pressure, screw speed, frictional heat, and so on in the plasticator. 

To a solution of 2-bromo-l,6-diene (0.627 mmol) in acetonitrile (5 mL) in a screw-capped Pyrex bottle were added Pd(OAc)2 (5 mg, 3.5 mol%), PPhj (12.8 mg, 8 mol%), silver carbonate (207 mg, 0.75 mmol) and the respective dienophile (0.74 mmol). The solution was purged with argon, and then stirred in the sealed bottle at 90 °C for 45 min. After the mixture had been cooled down to ambient temperature, the reaction mixture was filtered through a bed of charcoal and celite, and the solvent was removed under reduced pressure. The residue was purified by chromatography on silica gel (6.0 g, column 1.7 x 6 cm). For performing the second step under high pressure, the cooled mixture was filtered directly into a Teflon tube that was sealed and subjected to 10 kbar at 25 °C for 3 d colorless oil. 

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