Unit Hardening Treatment

Examples of the resistance of various plasticising screw and cylinder outfitting options are shown in Table 3.1. Table 3.2 lists the classifications of the various treatments and Table 3.3 gives recommendations for the type of outfitting for some common materials. From these three tables it should be relatively straightforward to ensure that the correct equipment is being used and wear and tear can be minimised. 

Metal treatment type Plasticising Resistant to abrasion Resistant to corrosion Thickness (mm) Hardness Temperature ran up to 

Note resistant very resistant generally all nozzles are in nitride execution with different steel types non-return valves in nitride execution on screws with Arbid Nitride = low abrasion Arbid = abrasion proof BMA = ultra low abrasion  

Abrasion proof Arbid/Arbid BMA/Arbid VSX/Arbid  

Thermoplastics without corrosive or abrasive components (LDPE, HOPE, PP, PS, CA) 

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As with the acid treatment, application can be made by shovel, hand-portable device, or larger wheeled or stationary units. A typical application measure might be a 10-lb pail of agent to a 10-ft2 spill, which is a typical 3-gallon spill. Treatment time is usually 10 to 20 minutes, during which period only a moderate amount of heat is produced. The resulting residue will also be pastelike and harden over time (ANSUL, 1991b). 

Another commercially important reaction is du Pont s synthesis of 1,4-hexadiene. This is converted to synthetic rubber by copolymerization with ethylene and propylene, which leaves the polymer with unsaturation. Unsaturation is also present in natural rubber, a 2-methylbutadiene polymer 12.13, and is necessary for imparting elastomer properties and permitting vulcanization, a treatment with Sg that cross-links the chains via C-S-C units and greatly hardens the material. 

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