Purging material

For each node v, where the offending chemicals (x, Xj) are present in the initial and goal states, respectively, find a directed path that leads the purgative material from its source to the sink through node u. 

A liquid purging material is available for cleaning out extruders, molders, or molds between colors. 

Do you understand why the recycle process without a purge stream will cause an impurity to build up even though the recycle rate is constant The purge rate is adjusted so that the amount of purged material remains below an acceptable specified economic level or so that the... 

A nearly equimolar mixture of ethylene and ethane is to be separated. The stream is available at about 3 atm, and high-purity (greater than 99%) ethylene is desired at greater than 95% recovery. An adsoibent with reasonable selectivity has been found which will desorb ethylene either at pressures well below atmospheric, or in the presence of a Cj hydrocaibon or heavier, or in the presence of various inert gases. Ethylene in turn cannot displace hydrocarbons with more than four carbons, however. In Table 12.6-1, the tme statements are 1,6, 7, and 9. Statement 9 is considered to be true because ciyogenic distillation would be required to separate the ethylene from the inert or purge material. In Table 12.6-2 we see that PSA is the most likely choice, using vacuum desorption. 

Cleaning one color or type of material from the processing machine by forcing it out with the new color or material to be used in subsequent production. Special purging materials are also available. 

Purge material should not be re-used. Re-used purge compound may work some of the time, but it will prove a false economy, through the re-introduction of cured rubber into the system. Examples of purge compound formulations are to be found in Appendix 7. 

PEI (Ultem) should be used as the purging material before and after molding. 

Typically, the injection molded article has low crystallinity upon molding with increased crystalhnity within 24 hours. Polyethylene plastic is an excellent purge material for injection molding machines. PHA plastics should be dried for 4 hours at 85 ° C prior to molding for improved mechanical properties. 

The injection machine was injecting 15 maximum shot size shots for HIPS. The first shot was injected with mixed mica materials. After injection the first shot, some mica particles still remained in both the barrel and the hot runner manifold. Those particles are assumed to simulate a color or contamination. The second to fifteenth shots used virgin material to purge the previous one and the mica particles. The purged materials were put into a water bath to cool down. Then, they were cut into small pieces and weighed and then put in a crucible for ash testing. 

The ASTM standard test method for ash content in plastics, D5630 - 01, was performed to measure the mass of mica particles in each purged material. Porcelain crucibles of 50 mL volume charged with the purged material were put in a muffle furnace at 900 °C for 60 minutes. The weights of samples before and after burnout were recorded to determine the amount of residual, mica particles... 

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