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Application
Guide: Reinforced Reaction Injection Molding
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Background:
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Reinforced
Reaction Injection Molding (RRIM) describes a method often seen
in automotive applications. This method differs from conventional
injection molding in that polymerization, via a chemical reaction,
occurs in the mold as opposed to melting and cooling to form a
solid polymer. RRIM is further characterized by inclusion of reinforcement
additives to provide improved physical properties
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| Products
For Selection: |
Features
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Benefits
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| Milled
Glass Fibers |
- Short
fiber lengths
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Wide variety of grades
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- Best
physical properties
- Specific
application advantage
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Wollastonite |
- Natural
mineral
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Short fibers with narrow diameter
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Needle-like shape
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- Improved
cost savings vs. some glass options
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Improved flow properties
- Improved
mechanical strengths vs. other minerals
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| Muscovite
Mica |
- High
purity ore
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Platy shape
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- Minimal
reactivity
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Warpage and shrinkage control
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| Microwool:
Processed Mineral Fiber |
- Low
bulk density
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Complex silicate chemistry
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Small diameter with long lengths
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Processed and surface treated in the U.S.
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- Lower
weight parts
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Lower wear on processing equipment
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Good physical properties
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Excellent compatibility with standard polyols
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Excellent economics
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Suggested
Loadings:
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| Product |
By
Weight |
| Microglass |
15
- 25 |
| Wollastonite |
15
- 22 |
| Muscovite
Mica |
6
- 8 |
| Microwool |
15
- 20 |
Note:
For maximum mechanical strengths balanced with warpage and shrinkage
control, it is highly suggested that formulating blends of
the reinforcements be incorporated.
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| Expected
Observations: |
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The noted
reinforcing fillers all will increase flexural modulus about 3
times over unfilled resin. Addition of 10 - 15% weight milled
glass fibers prevents waviness in long, thin parts. Fibrous fillers
can have more anisotropy. The platy particles, the mica, will
orient flat to the flow thus controlling warpage. To maximize
tensile strength, one suggestion could be to look at average lengths
of the fiber or needle-like products close to 500 microns. To
improve adhesion to the matrix proper selection of surface treatment
can be critical.
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Final determination of the
suitability of the material for the use contemplated is the
sole responsibility of the user. Manufacturer's only
obligation shall be to replace such quantity of the product
proven to be defective.
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