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 Property

Amorphous thermoplastic 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 Thermoplastic Semi-crystalline Thermoplastic
Cost ↓ HDT ↓ Cost ↓ HDT ↓
PEI PPSU PPS PPS
PPSU PEI PEEK Nylon
PSU PSU PVD POM
PPO/PPE PC PTFE PBT
PC PPO/PPE PET PVDF
ABS PMMA PBT PTFE
HIPS HIPS Nylon PET
PVC ABS POM PP
PETG PVC UHMW-PE HDPE
PMMA PETG HDPE LDPE
LDPE
PP

2. Mechanical Property – Tensile Strength

Amorphous MPa Semi-crystalline MPa
PEI 104.8 PEEK 96.5
PSU 70.3 Nylon (6cast) 69.0-93.1
PPSU 69.6 PPS 86.2
PMMA 69 Nylon (6/6 extruded) 85.5
PPO/PPE 66.2 PET 79.3
PC 65.5 POM (homopolymer) 69
PETG 53.2 POM (copolymer) 67.6
PVC 51.7 PBT 59.9
ABS 28.3 PVDF 53.8
HIPS 24.1 PP (homopolymer) 37.2
HDPE 27.6
PP (copolymer) 26.2
UHMW-PE 21.4
PTFE 10.3-20.7
LDPE 9.7
tensile strength

3. Mechanical Property – Flexural Modulus

Amorphous MPa Semi-crystalline MPa
PEI (30% glass-filled) 8963 PPS 4137
PC (20% glass-filled) 5516 PEEK 4068
PVC 3316 Nylon (6cast) 2896-3447
PEI 3309 POM (homopolymer) 2896
PMMA 3309 Nylon (6/6 extruded) 2827
PSU 2689 PET 2758
PPO/PPE 2551 POM (copolymer) 2551
PPSU 2413 PBT 2275
PC 2379 PVDF 2137
HIPS 2137 PP (homopolymer) 1551
PETG 2137 PP (copolymer) 1482
ABS 2096 HDPE 1379
UHMW-PE 758
PTFE 496
LDPE 207
Flexural Modulus

4. Mechanical Property – Impact Resistance

Amorphous J/m Semi-crystalline J/m
PC 641-854 LDPE no break
PPSU 694 UHMW-PE 961
ABS 411 PP (copolymer) 667
PPO/PPE 187 PTFE 187
HIPS 107 PVDF 160
PETG 91 PEEK 85
PSU 69 PBT 80
PEI 53 POM (homopolymer) 80
PVC 53 PP (homopolymer) 64
PMMA 21 Nylon (6/6 extruded) 64
POM (copolymer) 53
Nylon (6cast) 37-48
PET 37
PPS 27
Impact Resistance

5. Electric Insulation

Amorphous kv/mm Semi-crystalline kv/mm
PEI 32.7 Nylon (6cast) 19.7-23.6
PVC 21.4 POM (homopolymer) 19.7
PPO/PPE 19.7 POM (copolymer) 19.7
PMMA 16.9 PTFE 15.7-19.7
PSU 16.7 PEEK 18.9
PETG 16.1 PPS 17.7
PC 15 PET 15.7
PPSU 14.2 PBT 15.7
Nylon (6/6 extruded) 11.8-15.7
PVDF 11
Electric Insulation

6. FDA (Food and Drug Administration) Compliance

Q: Who meet FDA in amorphous thermoplastics?

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

Q: Who meet FDA in semi-crystalline thermoplastics?

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

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