1 / 25

Understanding BMC: Properties, Applications, and Chemical Composition

This article explores the chemistry of Bulk Molding Compounds (BMC) and their distinctive properties. BMCs are thermosetting materials that become permanently rigid when heated or cured, utilizing crosslinking mechanisms to enhance strength. We differentiate BMCs from thermoplastics, which can be remelted and reshaped. The article provides insights into resin choices, low-profile additives, fiberglass properties, and critical BMC metrics such as flexural strength, tensile strength, and thermal properties. Essential for engineers and material scientists developing advanced composite materials.

barton
Télécharger la présentation

Understanding BMC: Properties, Applications, and Chemical Composition

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Chemistry of BMC A World of Choices

  2. What a BMC Is • Thermoset • Having the property of becoming • permanently hard and rigid when • heated or cured. Uses crosslinking as • the mechanism to develop rigidity and • strength.

  3. What a BMC Isn’t • Thermoplastic • Having the property of softening or • fusing when heated and of hardening • and becoming rigid again when cooled; • thermoplastic materials can be • remelted and cooled time after time • without undergoing any appreciable • chemical change.

  4. Resin Choices • Different Acids and Alcohols • Isophthalic Acid • Maleic Acid • Fumaric Acid • Propylene Glycol • Diethylene Glycol • Neopentyl Glycol

  5. Styrene: Crosslinking Genius Dilutes the polyester resin and participates in the crosslinking of the polymers CH=CH 2 Styrene

  6. Low Profile Additives • Ranked from least effective to most effective • Polyethylene • Polystyrene • PolyMethylmethacrylate • Polyvinyl Acetate

  7. Polystyrene as a Low Profile Additive

  8. Filler (aka Ground Rock) • ATH • CAC03 • Clay • Graphite • Talc • And others.....

  9. ATH vs. CAC03 ATH CAC0 3 Which does your application require?

  10. Fiberglass • Sizing • Filament Diameter • Length • Amount

  11. In Line Fiberglass Process

  12. Additives • Initiators - temperature ranges • Pigments • Release Agents - Ca vs. Zn • Thickeners - Chemical vs. Physical • Antioxidants - Heat Stability • UV Stabilizers

  13. The Composite • Physical Form • Shrink, Density, Cure

  14. BMC Mixer

  15. BMC Property Range Glass Range, % Specific Gravity Mold Shrinkage, mil/in Flexural Strength, Kpsi Flexural Modulus, psi Tensile Strength, Kpsi Notched Izod, Fppi Water Absorption, %, 24 Hours Arc Resistance, sec Dielectric Strength, V/mil UL 94 Flame Resistance Heat Deflection @ 264 psi, Thermoconductivity, btu/hrs/ft2/0F/in Glass Transition Temperature, Tg 10-30 1.70-2.00 -1.0- +4.5 10-35 1.4-2.2 x 106 3-13 3-33 0.05-0.15 180 - 210 250 - 450 HB – V0 @ 1/32 °F 500+ 1.3-1.7 °C 145-210

More Related