Many products involve thermoplastics. It is a smart alternative to metal parts in most industries. However, thermoplastics is also a large field. You may want to know the exact differences when choosing the specific materials in product designing.

First let’s divide thermoplastics into two parts: amorphous and semi-crystalline.

Q: Who are amorphous plastics?

A: ABS, PS, PMMA, PPO/PPE, PETG, PC, PSU, PVC, PPSU, PEI

Q: Who are semi-crystalline plastics?

A: POM, HDPE, LDPE, Nylon, PBT, PEEK, PET, PP, PPS, PTFE, UHMW-PE

General Properties of Thermoplastics

Amorphous thermoplastics are:

✓Infusible, gradually softened, and fluidized in a wide range of heating temperature;

✓Transparent;

✓Lower in density;

✓Easier to process;

✓Easier to adhere through adhesives or solvent;

✓More ductile and more tenacious;

✓Used in structural parts, rather than bearing parts or wear-resistant parts (e.g. bearings).

Semi-crystalline thermoplastic are:

✓Infused at a certain temperature, instantly fluidized when being heated to the fusion point;

✓Higher in density, tensile strength, and modulus;

✓Higher in the contraction rate of injection molding;

✓Opaque;

✓Harder to crack under stress;

✓Better at organic-chemical resistance;

✓Better at creep and fatigue resistance;

✓Suitable for not only structural parts but also bearing parts and wear-resistant parts.

Now let’s start comparing these plastic materials in specific properties:

1. Heat Distortion Temperature (HDT) & Cost

Amorphous ThermoplasticSemi-crystalline Thermoplastic
COST ↓HDT ↓COST ↓HDT ↓
PEIPPSUPPSPPS
PPSUPEIPEEKNylon
PSUPSUPVDPOM
PPO/PPEPCPTFEPBT
PCPPO/PPEPETPVDF
ABSPMMAPBTPTFE
HIPSHIPSNylonPET
PVCABSPOMPP
PETGPVCUHMW-PEHDPE
PMMAPETGHDPELDPE
LDPE
PP

2. Mechanical Property – Tensile Strength

AMORPHOUSMPASEMI-CRYSTALLINEMPA
PEI104.8PEEK96.5
PSU70.3Nylon (6cast)69.0-93.1
PPSU69.6PPS86.2
PMMA69Nylon (6/6 extruded)85.5
PPO/PPE66.2PET79.3
PC65.5POM (homopolymer)69
PETG53.2POM (copolymer)67.6
PVC51.7PBT59.9
ABS28.3PVDF53.8
HIPS24.1PP (homopolymer)37.2
HDPE27.6
PP (copolymer)26.2
UHMW-PE21.4
PTFE10.3-20.7
LDPE9.7
tensile strength

3. Mechanical Property – Flexural Modulus

AMORPHOUSMPASEMI-CRYSTALLINEMPA
PEI (30% glass-filled)8963PPS4137
PC (20% glass-filled)5516PEEK4068
PVC3316Nylon (6cast)2896-3447
PEI3309POM (homopolymer)2896
PMMA3309Nylon (6/6 extruded)2827
PSU2689PET2758
PPO/PPE2551POM (copolymer)2551
PPSU2413PBT2275
PC2379PVDF2137
HIPS2137PP (homopolymer)1551
PETG2137PP (copolymer)1482
ABS2096HDPE1379
UHMW-PE758
PTFE496
LDPE207
Flexural Modulus

4. Mechanical Property – Impact Resistance

AMORPHOUSJ/MSEMI-CRYSTALLINEJ/M
PC641-854LDPEno break
PPSU694UHMW-PE961
ABS411PP (copolymer)667
PPO/PPE187PTFE187
HIPS107PVDF160
PETG91PEEK85
PSU69PBT80
PEI53POM (homopolymer)80
PVC53PP (homopolymer)64
PMMA21Nylon (6/6 extruded)64
POM (copolymer)53
Nylon (6cast)37-48
PET37
PPS27
Impact Resistance

5. Electric Insulation

AMORPHOUSKV/MMSEMI-CRYSTALLINEKV/MM
PEI32.7Nylon (6cast)19.7-23.6
PVC21.4POM (homopolymer)19.7
PPO/PPE19.7POM (copolymer)19.7
PMMA16.9PTFE15.7-19.7
PSU16.7PEEK18.9
PETG16.1PPS17.7
PC15PET15.7
PPSU14.2PBT15.7
Nylon (6/6 extruded)11.8-15.7
PVDF11
Electric Insulation

6. FDA (Food and Drug Administration) Compliance

Q: What amorphous thermoplastics meet FDA?

A: PMMA, PSU, PETG, PVC, PC, PPSU, HIPS, PEI

Q: What semi-crystalline thermoplastics meet FDA?

A: POM, PET, HDPE, LDPE, PP, PTFE, Nylon, PVDF, PBT, UHMW-PE, PEEK

7. Thermoplastic Applications

Now we have learned the basic knowledge of thermoplastics. In the next part, we will discuss their application, especially in the field of car body panels.

Get a Quote