Processing methods reaction injection molding

Typical processing methods - extrusion, injection molding, reaction injection molding, thermoforming ... 

Different casting processes are used. They tend to overlap and could be identified by other processing methods. An example is liquid injection molding that can be identified as injection molding (Chapter 4) or reaction injection molding (Chapter 12). Many decades ago the reaction injection molding process was initially called liquid injection molding. 

The latest trend in foamed composites is automotive structural parts produced by the SRIM (structural reaction-injection-molding) process. The SRIM process is a method of the reactive liquid injection molding (i.e., LIM). LIM includes RIM (reaction injection molding), RRIM (reinforced RIM) and RTM (resin transfer molding). IX M (Liquid Composite Molding) is a relatively new technical term which includes SRIM, RRIM and RTM (Resin Transfer Molding). 

Important processing methods mixing/compounding, injection molding, extrusion, Banbury mixer, two-roll mills, cold feed extruders, reaction injection molding... 

If glass fibers are added to get reinforcement, the method is known as RRIM (Reinforced Reaction Injection Molding). Structural RIM (SRIM) is the process whereby the reinforcement fabric or mat (glass, carbon) are placed in the mold and the resin is injected to impregnate the reinforcement. 

NIR transmittance spectroscopy was used to monitor polyurethane reaction extent in situ during a reaction injection molding (RIM) process. Good agreement was observed between multivariate (PGA) analysis, univariate (Beer-Lambert) analysis, and kinetic predictions. It was demonstrated that PGA methods with carefully chosen spectral ranges could provide estimation of the reaction extent without time-consuming calibration [83]. 

Processibility still remains a concern, since processibility appears to be much easier to obtain for undoped conducting polymers than for the same polymers in doped forms. If the polymer must be doped after fabrication of a shaped article, the problem of introducing the dopant uniformly is serieous, especially when it is required that the same dopant which easily diffuses into the article must eventually be thermally stable. What is needed here appears to be new methods for processing conducting polymers. One attractive possibility would be a process analogous to conventional RIM (reaction injection molding) in which polymer articles are directly fabricated from a mixture of monomer and dopant. 

Of all the methods for the production of block and graft polymers, the greatest importance, from the view of commercial simplicity, involves mechanical synthesis. The block and graft reactions can be potentially performed directly during polymer processing and in standard equipments, such as internal mixers, injection molding machines, and extruders. 

Chemical activities in the field of mass screening are often related to combinatorial chemistry [51,52]. One major goal, especially in the field of solid phase chemistry involving polymers like DNA or peptides, aims at the increase in the number of compounds per reactor volume and time. Commercially available microtiter plates are established as reactors in this case whereby robotic feed systems fit perfectly to their dimensions. A drastic reduction of reaction volume and increase in number of reaction vessels ( wells ) leads to the so-called nanotiter plates (e.g. with 3456 wells). Microfabrication methods such as the LIGA process are ideal means for the cost effective fabrication of nano-titer plates in polymeric materials by embossing or injection molding techniques so that inexpensive one-way tools are realized. 

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