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Some specific polymers

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Presentation on theme: "Some specific polymers"— Presentation transcript:

1 Some specific polymers
H2C-C-C{-O C O-}nC-C-CH2 H-C-H H epoxy O Some specific polymers hardener H2N-R-NH2 Prepregs

2 Composites - overview Example - carbide tools (previously discussed) Co matrix phase angular WC fragments

3 Composites - overview Artificial combination of matrix phase & dispersed phase Matrix: metal, alloy ceramic mat'l polymer Dispersed phase: particulate fiber

4 Composites - metal matrix composites (MMCs)
Particulates: ThO2-dispersed Ni (TD Ni) sintered Al powder (SAP) Works like precipitation hardening - except strengthening maintained at hi T Improves: strength creep resistance hi T corrosion resistance

5 Composites - metal matrix composites (MMCs)
Fibers: Conts - C, SiC, B, Al2O3 Disconts - C, Al2O3 , SiC whiskers Matrix mat'ls May get rxn betwn phases at hi T

6 Composites - ceramic matrix composites (CMCs)
Particulates, fibers: SiC, B, Al2O3 , C, SiC & Si3N4 whiskers Matrix Improve fracture toughness: slow crack growth deflect crack tips redistribute stresses around crack tips bridge crack tips

7 Composites - polymer matrix composites (PMCs)
Fibers: mainly - glass (GFRPs), carbon (CFRPs), aramid, others - B, SiC, Al2O3

8 Composites - polymer matrix composites (PMCs)

9 Composites - polymer matrix composites (PMCs)
Very common - polyesters, vinyl esters

10 Composites Role of matrix in FR composites: a. transfer stresses betwn fibers b. provide barrier to environment c. protect fibers Matrix/fiber bond: matrix must wet fiber physical & chemical bond desirable mechanical interlocking Fibers frequently coated w/ coupling agent

11 Composites non-coupled coupled

12 Composites Fibers - variables amount fiber length distribution orientation Fiber orientation can be random aligned intermediate


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