Thermosets, Reinforcements, and Laminates

What is the difference between rigid and flexible thermosets?

rigid thermosets are made up of short chains with many crosslinks
flexible thermosets are made up of long chains with few crosslinks

Compare the resistance to heat and stability between thermoplastics and thermosets

thermosets have greater resistance to heat and are more stable than thermoplastics

What are the two types of curing processes a thermoset goes through, and what are the differences?

1. Condensation process - has a byproduct (like water or gas)

2. Addition process - no byproduct

An uncured polymer is also known as what?

a resin

Wha tis the difference between a catalyst and promoter?

a catalyst trigger the curing process while a promoter affects the rate of curing (with accelerators and inhibitors)

Which type of resin begins as a rubber like material?

polyester resin

Which type of resin begins as a syrup-like liquid?

epoxy resin

Which resin is most versatile?

polyester resin

What type of resin has good UV resistance and is transparent?

acrylic resin

Between polyester and vinyl ester resins, which has a better bonding properties when laminating?

vinyl ester resins

Rank the following resins according to strength form least to greatest: polyester, vinyl ester, and epoxy

polyester, vinyl ester, and epoxy

What is a giveaway that vinyl ester is between polyester resin and epoxy resin?

vinyl ester resin has a polyester chain with an epoxy backbone

Which type of fiberglass is utilized in elecrical applications?

quartz

Fiberglass improves the mechanical properties of plastic by a factor of what?

2

What type of fiberglass fibers are the strongest?

continuous, long fibers

While carbon fiber isn’t exactly stronger than other mateirials, it has a higher___

modulus (stiffness)

What are the 3 pros for carbon fiber?

1. high modulus

2. good fatigue resistance

3. there is no plastic range (goes from elastic to failure) [good creep resistance]

What are the 5 cons for carbon fiber

1. brittle

2. expensive

3. low impact strength

4. low compression strength

5. low break extension (doesn’t elongate when broken)

What are the properties for Kevlar

1. high impact strength

2. high modulus

3. lightweight and strong

Where would you see Kevlar in the real world?

bullet-proof vests, helicopter blades

Basalt is very similar with carbon fiber, EXCEPT

there is less itch with basalt compared to carbon fiber

What is a composite?

a combination of a reinforced material (like a fiber) with a matrix (like a resin)

What is autoclaving?

using a machine that gives you increased pressure during lamination to get a better end result

What is the psi range that is used for vacuum bag molding?

15-1000 psi

What are reasons why one might choose a composite instead of a metal?

1. lighter material

2. better insulation

3. better corrosion resistance

Wha

What are the cons on doing the Wet Layup lamination method?

uniformity is difficult to get

For the Prepreg Layup lamination method, what is often needed?

autoclave becasue heat is needed to cure

Compare and describe the shelf life for the Wet Layup and Prepreg Layup lamination methods

The Wet Layup method has a longer shelf life than the Prepreg layup method because the bag is always dry (you can leave them on the shelf and use whenever)

Prepreg is already wet, with is having the resin in already so you need to use it fast before it cures on its ownThe

What are the three common matrix materials for lamination?

polyester, vinyl ester, epoxy

What are the thee common fibers?

fiberglass, carbon fiber, and Kevlar (aramid)