MODULE 6D - POLYMERS

Structural rigidity under load

Plastics are materials that have ___.

Thermoplastic, thermosetting

Plastics are either ___ or ___.

Optical transparency

Polystyrene and poly(methyl methacrylate) are used when ___ is critical.

Nonstick cookware, bearings

Fluorocarbons are used for ___.

Vulcanization

Elastomer properties depend on the degree of ___.

Carbon black

Mechanical properties of rubbers are improved by additives such as ___.

SBR

The most important synthetic elastomer is ___.

Automobile tires

SBR is used for ___, reinforced with carbon black.

NBR

The elastomer used when highly resistant to degradation is ___.

-90°C to 250°C

Silicone elastomers are flexible from ___ to ___.

Automobile engine compartment

Silicone elastomers are used in ___.

Biocompatibility

Silicone elastomers are valued for ___.

100:1 length-to-diameter ratio

Fibers must have at least a ___.

Textile industry

Fibers are primarily used in the ___.

Aramid fibers

Fibers employed in composite materials are ___.

Protect from environment, improve appearance

Coatings are applied to ___.

Electrical insulation

Coatings are also used to provide ___.

Paint, varnish

Common coatings include ___.

Latex

A stable suspension of polymer particles in water is called ___.

Bond together two solid surfaces

Adhesives are substances used to ___.

Mechanical, chemical

Types of adhesive bonding mechanisms are ___.

Polyurethanes, epoxies, silicones

New synthetic adhesive materials include ___.

0.025–0.125 mm

Polymeric films have thicknesses between ___.

Low density, high flexibility

Polymeric films are characterized by ___.

Bags for packaging food products

Polymeric films are used as ___.

Small pores and trapped gas bubbles

Foams contain a high volume percentage of ___.

Polyurethane, polystyrene, rubber

Common foam materials include ___.

Cushions, packaging, thermal insulation

Foams are commonly used for ___.

Matrix, dispersed phase

Most composites are made of two phases: ___.

Continuous phase

The matrix phase is the ___ present throughout the material.

Concentration, size, shape, distribution, orientation

Composite properties vary depending on ___.

Aerospace, underwater, transportation

Applications of composites include ___.

Particle reinforced, fiber reinforced, structural

Classifications of composites include ___.

Tiny particles

Particle-reinforced composites use ___ as dispersed phase.

Large particle, dispersion strengthened

Particle-reinforced composites are classified as ___.

Concrete

A large particle composite made of cement, sand, and gravel is ___.

Cement

The matrix in concrete is ___.

Cermets

A composite of metal matrix and ceramic particles is called ___.

Cobalt or nickel

The metal matrix in cermets is ___.

Tungsten carbide, titanium carbide

The ceramic particles in cermets are ___.

Atomic or molecular level

In dispersion-strengthened composites, phase interaction occurs at ___.

Thoria dispersed nickel

A nickel alloy with 3% thoria is called ___.

Length-to-diameter ratio

Fibers in composites are characterized by their ___.

High strength, stiffness, elastic modulus

Fiber-reinforced composites provide ___.

Continuously, discontinuously arranged

Fiber-reinforced composites are classified based on fiber ___.

Orderly aligned fibers

Continuously arranged fiber composites have ___.

Randomly arranged fibers

Discontinuously arranged fiber composites have ___.

Homogeneous and composite materials

Structural composites are made of ___.

Laminar, sandwich composites

Structural composites are classified as ___.

Two-dimensional sheets or panels

Laminar composites are composed of ___.

Preferred high-strength direction

Laminar composites have a ___.

Plywood

An example of a laminar composite is ___.

Lightweight, high stiffness and strength

Sandwich composites are designed to be ___.

Two outer sheets and a thicker core

Sandwich composites consist of ___.

Roof, floors, walls

Sandwich composites are used in ___.

Replacement of diseased or damaged parts

Biomaterials are used for ___ in the human body.

Inert, compatible with body tissues

Biomaterials must be ___ and ___.

All material types

Biomaterials may be made from ___.