塑料的收缩率一般是指塑料制品冷却固化经脱模成型后，其尺寸与原模具尺寸间之误差百分比，可依ASTM D955方法测得。 在塑料模具设计时，须先考虑收缩率，以免造成成品尺寸的误差，导致成品不良。以下列举几项常用塑料原料之收 缩率比较。现总结常用塑料的收缩率如下：
| 塑料品种 | 原料收缩率 | 改性料类别 | 改性料收缩率 |
| ABS | 0.4-0.7 |
ABS+20%GF |
0.2-0.4 |
|
|
|
ABS+FR |
0.4-0.7 |
|
|
|
ABS+20%GF+20%FR |
0.1-0.3 |
| PC/ABS |
|
35%PC |
0.4-0.6 |
|
|
|
PC/ABS+20%GF |
0.2-0.4 |
|
|
|
PC/ABS+FR(Br) |
0.3-0.6 |
| AS | 0.4-0.6 |
|
|
| HIPS | 0.5-0.6 |
|
|
| PS | 0.3-0.6 |
|
|
| SAN | 0.5-0.6 |
|
|
| LDPE | 1.5-5.0 |
|
|
| HDPE | 1.5-3.0 |
|
|
| PP | 1.0-2.5 |
PP+20%talc |
1.0-1.5 |
|
|
|
PP+20%GF |
0.5-0.8 |
|
|
|
PP+FR（溴系） |
1.5-1.8 |
|
|
|
PP+20%GF+FR |
0.3-0.5 |
| PC | 0.8 |
PC+20%GF |
0.3-0.5 |
|
|
|
PC+20%GF+FR(无卤) |
0.2-0.4 |
| PET | 1.2-2.0 |
|
|
| PBT | 1.5-2.5 |
|
|
| PA6 | 0.5-2.2 |
PA6+30%GF |
0.3-0.5 |
|
|
|
PA6+30%GF+FR(无卤) |
0.2-0.4 |
|
|
|
PA6+30%填充 |
0.6-0.9 |
| PA66 | 0.5-2.5 |
PA66+30%GF |
0.4-0.7 |
|
|
|
PA66+30%GF+FR |
0.2-0.4 |
|
|
|
PA66+FR(无卤) |
0.8-1.2 |
| PPS | 0.2 |
|
|
| PPO | 0.5-0.7 |
|
|
| PF | 1.2 |
|
|
| EP | 0.2 |
|
|
| PTFE | 3.5-6.0 |
|
|
| POM | 1.9-2.3 |
|
|
| PMMA | 0.1-0.8 |
|
|
| PVC-rigid | 0.5 |
|
|
