reaction injection molding - pennsylvania state...
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Reaction Injection Molding
Figure 1: C.W. Macosko, Fundamentals of R.I.M. (Hanser, 1989).
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Reaction Injection MoldingBASIC CHEMISTRY
polyol + isocynate → polyurethane
with no volatile byproduct
Polyols: chains are PEO, PPO
Diol:
Triol:
Isocyanates:
MDI: (most common)
PPI: (where n=3,4,5 (mixture))
TDI:
HDI:
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Reaction Injection MoldingIMPINGMENT MIXING FOR RIM AND
RRIM
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Reaction Injection Molding
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Reaction Injection Molding
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Reaction Injection Molding
Advantages:
1. Low viscosity - large parts with thin sections are no problem.
2. Easy to incorporate fillers
3. No regrind
4. No weld lines
Problems:
1. Incomplete mixing
2. Toxic monomers (isocyanates smell bad)
3. Chemistries are limited to those that form crosslinks without a volatilebyproduct (chiefly polyurethanes)
4. No way to recycle thermosets
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