Thermoplastic Material Selection Guide

Disclaimer:

The information presented below is of a general nature and shall not be relied upon other than for preliminary material identification purposes only.


ABS (Acrylanitrile Butadiene Styrene)

ABS is an amorphous polymer with good Impact Strength and excellent appearance. It is easy to process and is widely used for computer housings, small appliances, automotive interior trim, and medical components. It is available in flame retardant grades, and medical grades. ABS has poor chemical resistance.

Tensile Strength
5000-7500 psi

Flexural Modulus
270,000-380,000 psi

Impact Strength
3.0-7.5 ft-lb/in notched izod

Maximum Temp.
200 F short duration, 140 F long term

Chemical Resistance
poor to fair

Cost
$$$

Brand Names
Cycolac (GE) Lustran (Monsanto)


ABS-Polycarbonate Alloy

These alloys offer improved strengths over ABS at a lower cost than Polycarbonate. Exceptional low temperature Impact Strength. Flame retardant grades are available. Due to the world shortage of polycarbonate production capacity, lead times for these materials are long, and availability is limited.

Tensile Strength
6400-9150 psi

Flexural Modulus
300,000-400,000 psi

Impact Strength
8-12 ft-lb/in notched izod

Maximum Temp.
210 F short duration, 140 F long term

Chemical Resistance
poor to fair

Cost
$$$$

Brand Names
Cycoloy(GE), Pulse(Dow)


Acetal (POM)

Acetal polymers are semi-crystalline. They offer excellent inherent lubricity, fatigue resistance, and chemical resistance. Acetals suffer from outgassing problems at elevated temperatures, and are brittle at low temperatures. Glass filled, and added lubrication grades are available, flame retardant grades are not.

Tensile Strength
6000-22,000 psi

Flexural Modulus
120,000-170,000 psi 1,200,000 psi with carbon fiber

Impact Strength
.8-2 ft-lb/in notched izod, 15 lb/in for impact modified grades

Maximum Temp.
300 F short duration with filled grades, 180 F long term

Chemical Resistance
excellent

Cost
$$$

Brand Names
Duracon (Celanese), Delrin (Dupont)


PMMA, Acrylic

Acrylics are amorphous polymers with excellent clarity. They are widely used in optical applications. Acrylics also have excellent weather ability and do very well in outdoor applications.

Tensile Strength
6000-11,000 psi

Flexural Modulus
200,000-600,000 psi

Impact Strength
.2-.4 ft-lb/in notched izod, 2.5 lb/in for impact modified grades

Maximum Temp.
220 F short duration , 170 F long term

Chemical Resistance
excellent

Cost
$$

Brand Names
Perspex (ICI), Plexiglas (AtoHass)


Nylon 6

Nylons are semi-crystalline polymers with a good range of properties. Nylons are widely used because they have a good cost to performance ratio. Lower numbered nylons, 6 ,6-6, 4-6, absorb moisture and change their properties as a result. Nylons have been compounded with reinforcements, fillers and additives to produce a very wide variety of properties. Nylon 6 has the lowest modulus of all nylon grades.

Tensile Strength
6,000-24,000 psi up to 36,000 psi with long glass or carbon

Flexural Modulus
390,000-1,100,000 psi 2,000,000 with long glass fiber or carbon

Impact Strength
2-8 ft-lb/in notched izod

Maximum Temp.
~300 F short duration 200 F long term

Chemical Resistance
Good to Excellent

Cost
$$$

Brand Names
lots


Nylon 6-6

Nylons are semi-crystalline polymers with a good range of properties. Nylons are widely used because they have a good cost to performance ratio. Lower numbered nylons, 6 ,6-6, 4-6, absorb moisture and change their properties as a result. Nylons have been compounded with reinforcements, fillers and additives to produce a very wide variety of properties. Nylon 6-6 offers better properties than nylon 6 without being as costly as nylon 4-6. It has the best abrasion resistance of all nylons. Verton, long glass fiber filled materials, by LNP, are excellent metal replacement materials.

Tensile Strength
8,000-24,000 psi up to 36,000 psi with long glass or carbon

Flexural Modulus
430,000-1,100,000 psi 2,000,000 with long glass fiber or carbon

Impact Strength
2-8 ft-lb/in notched izod

Maximum Temp.
~350 F short duration 220 F long term

Chemical Resistance
Good to Excellent

Cost
$$$

Brand Names
Celanese Nylon (), Verton (LNP), Zytel (Dupont)


Nylon 11

Nylons are semi-crystalline polymers with a good range of properties. Nylons are widely used because they have a good cost to performance ratio. Higher numbered nylons, 11,12, do not absorb moisture to the extent that lower numbered nylons do, as a result their properties are more stable over a wide range of conditions. However , they are more expensive. These Nylons have been compounded with reinforcements, fillers and additives to produce a very wide variety of properties. Nylon 11 offers better Impact Strength and dimensional stability than lower numbered nylons. It is also more flexible.

Tensile Strength
8,000-17,000 psi

Flexural Modulus
170,000-1,200,000 psi

Impact Strength
2-No Break ft-lb/in notched izod

Maximum Temp.
~250 F short duration 180 F long term

Chemical Resistance
Good to Excellent

Cost
$$$$$

Brand Names
Rilsan(Elf AtoChem)


PBT Polyester (Polybutylene Terepthalate)

PBT polyesters are semi-crystalline. They are versatile materials with a good range of properties. They have excellent electrical properties and are abrasion resistant. PBT has been extensively compounded giving a very wide range of properties. PBT performs much like Nylon but can handle higher temperatures and does not absorb moisture. PBT has excellent impact strength but is very notch sensitive.

PBT is very anisotropic in shrinkage, so it is difficult to mold to extremely tight tolerances.

Tensile Strength
6,000-13,000 psi

Flexural Modulus
300,000-1,200,000 psi

Impact Strength
1 ft-lb/in notched izod . 30+ ft-lb/in un-notched

Maximum Temp.
420 F short duration 250 F long term

Chemical Resistance
Fair to Good

Cost
$$$

Brand Names
Celanex (Hoechst Celanese), Valox (GE)


LCP (Polyester Liquid Crystal Polymer)

LCPs are cool, relatively new materials with interesting properties. They have Tensile Strength and modulus close to aluminum.

Because of the highly oriented, rod like nature, of the polymer molecules, LCPs present some interesting design challenges. This is because the molecules will only form in straight lines. Additionally, the high orientation only occurs within about .040 of the surface of the part. Molecular orientation below this skin is random. As a result all of the strength of the material is in the skin.

Good design data is not available for these materials, so prototyping is a must. prototypes must be molded, because of the molecular orientation mentioned above.

Tensile Strength
12,000-32,000 psi

Flexural Modulus
1,300,000-4,600,000 psi with carbon fiber 3.2x10E6 with glass fiber

Impact Strength
1.1-11 ft-lb/in notched izod

Maximum Temp.
500 F short duration 430 F long term

Chemical Resistance
Good to Excellent

Cost
$$$$$$$$

Brand Names
Vectra (Hoechst Celanese), Xydar (Amoco)


PP, Polypropylene

Polypropylene is a widely used, semi-crystalline material. It has been extensively compounded to provide a wide range of properties at a wide range of costs. In general, polypropylene is a low temperature material with excellent chemical resistance. It has no known solvent at 73 F.

Polypropylene is difficult to mold to extremely close tolerances .

Tensile Strength
4,500-18,500 psi

Flexural Modulus
210,000 -1,500,000 psi

Impact Strength
1.4-5.5 ft-lb/in notched izod

Maximum Temp.
Up to 300 +F short duration 150 F long term

Chemical Resistance
Excellent

Cost
$ to $$$


PC, Polycarbonate

Polycarbonate is an amorphous material with excellent Impact Strength, clarity, and optical properties. It is very widely used and a wide variety of compounds are available. Polycarbonate is a victim of its own success as worldwide production is at capacity, and there are currently long lead times for this material.

Polycarbonate has excellent mechanical properties, and can be molded to tight tolerances. It is attacked by solvents and petrochemicals, and its weatherability is only adequate.

Tensile Strength
9,000-23,000 psi

Flexural Modulus
340,000-1,400,000 psi

Impact Strength
2- 18 ft-lb/in notched izod
Bulletproof un-notched

Maximum Temp.
300 F short duration 150 F long term

Chemical Resistance
Poor to Fair

Cost
$$$$

Brand Names
Caliber (Dow), Lexan (GE)


Polyimide (Thermoplastic) (Aurum)

Polyimides offer excellent properties at high temperatures. A thermoplastic version of this material became available recently. Both amorphous and crystalline grades are offered. Polyimide materials are attacked by alkali and are very expensive.

Tensile Strength
13,000-36,000 psi

Flexural Modulus
420,000 -2,800,000 psi

Impact Strength
1.7-2.2 ft-lb/in notched izod

Maximum Temp.
580 +F short duration 450 F long term

Chemical Resistance
Good - attacked by alkali

Cost
$$$$$$$$$$$$$$$$!!! (expensive stuff)


PPO Modified Polyphenylene Oxide (Noryl)

By itself PPO is an excellent material with wonderful properties, unfortunately it cannot be processed by conventional means. As a result, PPO has been modified by placing it in a styrene matrix to create a readily processable amorphous material with properties superior to ABS. Modified PPO has good Impact Strength, stiffness, surface appearance, and flame retardency. It has fair to good chemical resistance too, but is more expensive compared to ABS.

Tensile Strength
6,000-18,000 psi

Flexural Modulus
270,000 -1,400,000 psi

Impact Strength
1.3-8.5 ft-lb/in notched izod

Maximum Temp.
200 +F short duration 120 F long term

Chemical Resistance
Fair to Good

Cost
$$$$

Brand Names
Noryl (GE)


PPS Polyphenylene Sulfide

PPS is a high temperature semi-crystalline material. It has good mechanical properties and excellent chemical resistance at elevated temperatures. PPS has been compounded extensively and many different types of properties are available. PTFE filled PPS is one of the best bearing materials available.

Unfilled grades of PPS have poor properties, so components are usually made from glass filled or glass/mineral filled grades.

PPS is very sensitive to molding conditions and must be processed properly to achieve its maximum potential.

Tensile Strength
14,000-28,000 psi

Flexural Modulus
550,000 -2,900,000 psi

Impact Strength
.5-6 ft-lb/in notched izod

Maximum Temp.
500 +F short duration 450 F long term

Chemical Resistance
Good to excellent

Cost
$$$$ to $$$$$$$


Polysulfone

Polysulfone is a high temperature amorphous material with relatively low cost. It is transparent and can be used at temperatures of up to 300 F. Polysulfone has been compounded, with glass and mineral filled grades available.

Tensile Strength
9,500-18,000 psi

Flexural Modulus
390,000-1,500,000 psi

Impact Strength
.65-7 ft-lb/in notched izod

Maximum Temp.
350 F short duration 300 F long term

Chemical Resistance
Fair to Good

Cost
$$$$$