Exam 2 - Polymer Reinforcement

Question 1

Polymer Reinforcement

Answer 1

• Adding of some agent to improve or reinforce
the plastic
– Usually used to enhance the strength of the base
resin

Question 2

forms of polymer reinforcement

Answer 2

– Continuous, short, particle

– Glass, metals, ceramics, polymers

Question 3

Can thermosets/thermoplastics be used in polymer reinforcement?

Answer 3

• Both thermosets and thermoplastics can be
used to produce composites
– Historically mostly thermosets, but now more and
more thermoplastics.

Question 4

Matched-Die

Answer 4

• Usually uses bulk-molding (BMC) and sheet-molding (SMC) compounds
• The SMC or BMC is then
compression molded in
matched mold steel dies

Question 5

bulk-molding compound (BMC)

Answer 5

• Putty-like mixtures of resin, catalysts, fillers and
short fiber reinforcements < 0.38 mm long
• Gunk, putty, dough or slurry molding

Question 6

sheet-molding compounds (SMC)

Answer 6

• Leather-like mixtures

* Flow mat or mold mat with longer fibers.

Question 7

Matched-Die Uses

Answer 7

• Transportation 
– Vehicle body panels and hoods (SMC) 
– Small boat hulls (SMC) 
• Appliances 
– Shower floors (BMC) 
– Heater housings (BMC) 
– Cases (BMC) 
– Components (SMC)

Question 8

Matched Die Advantages

Answer 8

– Finished surfaces (interior and exterior)
– Complex shapes (e.g., ribs and thin details)
– Minimum trimming of parts
– Good mechanical properties, close tolerances and corrosion
resistance
– Low costs and reject rates

Question 9

Matched Die Disadvantages

Answer 9

– More equipment, handling and storage needed for pre-form, BMC, TMC, XMC and SMC
– Close tolerances require precise parallel press guides
– Costly molds and tooling vs. open molds
– Porous or wavy surfaces may result
– Cannot be transparent.