Common plastic specific gravity and shrinkage rate summary

- Jun 18, 2019-

Shrinkage rate refers to the percentage of the size difference between the size of the parts at the molding temperature and the size difference after the parts are taken out of the mold and cooled to room temperature. It reflects the degree of the size reduction of the parts after they are taken out of the mold and cooled.


The factors affecting shrinkage rate include: material varieties, forming conditions, mold structure, etc., the shrinkage rate of different materials is different.

Shrinkage also has a great deal to do with the shape of the plastic parts, the complexity of the internal structure, whether there are embedded parts, etc.


Common plastic specific gravity, shrinkage and other parameters are as follows:


Chinese specific gravity shrinkage (%) drum temperature mold temperature

LDPE low density polyethylene 0.92 3 220~260 20~40

HDPE high density polyethylene 0.96 3 190~280 30~70

PP PP 0.91 2 210~280 20~50

PVC 1.38~1.41 1.5 170~190 20~40

ABS propylene - butadiene - styrene 1.05 0.6 210~260 50~80

AS propylene - styrene 1.07 0.6 220~270 40~80

BS butadiene-styrene 1.01 0.5 190~230 30~50

GPPS general purpose polystyrene 1.16 0.3~0.6 200~250 40~60

HIPS high impact polystyrene (changed to benzene) 1.08 0.5 210~270 20~50

EVA vinyl acetate 0.95 2 140~200 20~40

PMMA polymethylacrylate 1.18 0.6 220~240 60~80

PA6 polyamide-6 1.13 0.77-1 250~270 40~60

PA66 polyamide -66 1.13 1.3 280~300 40~60

PA66+30%GF polyamide-66 +30% glass fiber 1.39 0.3 240~270 80~90

POM polyformaldehyde 1.42 2.1 205~225 80~100

PC polycarbonate 1.2 0.5 271~293 71~93

PET polyethylene terephthalate 1.33 0.4 277~293 15~30

PET+30%GF polyethylene terephthalate +30% glass fiber 1.67 0.2 265~305 95~150

PETG modified polyester 1.27 0.2~0.5 250~270 15~40

PCTG modified polyester 1.23 0.2~0.5 275~295 15~40

PBT polybutylene terephthalate 1.4 1.5~2.2 225~245 40~80

PBT+30%GF polybutylene terephthalate 1.61 0.4~0.9 225~250 40~100

PCT+30%GF modified polyester +30% glass fiber 1.45 0.1~0.4 295~370 105~135

CA cellulose acetate 1.26 0.5 160~230 40~60

CAP propionate cellulose 1.2 0.5 215~240 40~75

CAB cellulose butyrate 1.19 0.5 230~250 40~85

PP high temperature resistant polypropylene 1.12 0.9~1.1 180~220 60~80

PP fireproof polypropylene 0.95 1.4 180~220 30~50

PPS+40%GF polyphenylene sulfide +40% glass fiber 1.67 0.25 300~340 120~150

PPO polyphenyl ether 1.07 0.5~0.8 270~310 70~93

PSU polysulfone 1.24 0.5 330~360 120~160

PES 1.37 0.68 340~380 120~160

LCP liquid crystal polymer 1.7 0.02 385~400 35~200

SBS styrene block copolymer 0.96~1.1 1.5 145~160 25~30

SEBS hydrogenated styrene block copolymer 0.87~0.91 1.6 180~220 35~65

TPU thermoplastic polyurethane 1.24 1.2 190~220 24~49

TPV fully vulcanized polyolefin elastomer 0.97 1.5~2.5 180~190 10~80

TPEE polyester elastomer 1.2 1.4 220~250 45

1