Material Process & Properties
The main difference between the LPMC™ made by Preferred Molding Compounds and materials made by our competitors, is that it is physically thickened instead of being chemically thickened. Our material uses “Crystic Impreg Technology” as the additive that physically thickens our material.
The process of producing LPMC™/SMC can be described in the following way. It is a mixture of polymer resin, inert fillers, fiber reinforcement, catalysts, pigments, stabilizers, release agents, and thickeners. The material is sheathed on the top and bottom by a nylon plastic film to prevent auto-adhesion. The paste is spread evenly onto the bottom film.
Chopped glass fibers are randomly deposited onto the paste. The top film/paste meets with the lower paste/fiber mixture and the sandwich is rolled into a thickness that is pre-determined. Our LPMC™ is ready to be used immediately, no cure time is necessary.
Thermoset compounds are used because of their high thermal stability, low coefficient of thermal expansion (when compared to steel), high impact strength, relatively low weight, and their receptiveness to paint.
Superior electrical insulation, heat resistance, and dielectric properties make LPMC™/SMC an excellent choice for insulating components of switch gear, circuit breakers, stand off insulators, and motor brush holders.
Thermoset compounds exhibit excellent electrical resistance due to the network of cross-linked molecules that create a rigid structure, where chemical bonds hold molecules in place. These compounds have the ability to maintain both physical and electrical properties under mechanical loads during prolonged exposure to high temperatures.
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MECHANICAL PROPERTIES COMPARISON
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TEST
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LPMC™
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SMC
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Glass Content (%)
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27
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27
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Moisture Absorption (%)
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0.30
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0.30
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Specific Gravity
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1.844
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1.824
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Flexural Modulus @ 72 °F (22 °C)
0.5 mm deflection (MPa)
2.5 mm deflection (MPa)
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11,840
7,971
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12,600
8,302
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Flexural Modulus @ 302 °F (150 °C)
0.5 mm deflection (MPa)
2.5 mm deflection (MPa)
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5,151
3,905
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5,641
4561
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Flexural Strength (MPa)
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169
|
161
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Tensile Strength (MPa)
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82.0
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76.9
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Unnotched Izod Impact (J/m)
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1,084
|
915
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