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Plastic Material: Density & Specific Gravity

Definition: Density v.s. Specific Gravity
Density and specific gravity sound quite similar, some even say that they are synonyms; however, they are actually not the same, below we are going to introduce the differences of them.

What's the meaning of "Density"?
Density is mass or weight of a substance per unit volume under normal temperature and pressure.

First, we have to know that the formula of density is:

D = M / V
D = Density ; M = Mass ; V = Volume

As formula shown, density is total mass of the object divided by total volume of object, which means: 1 gram per cubic centimetre or 1 kilogram per cubic metre.
Density of water is 1 gram per cubic centimeter (1 g/cm3), but actually, the exact density of water is not really 1 g/cm3, but rather a bit less (very, very little less) than 1, so we can say that generally the weight and volume of water is the same.

What's the meaning of "Specific Gravity"?
Specific Gravity means specific value of an object under normal temperature and pressure.

The formula or specific gravity is:

Specific Gravity = Dobject / DH2O
Dobject = Density of the object ; DH2O = Density of water
 

The difference of Density & Specific Gravity

"Density" has its own unit of measurement, 1 g/cm3 or 1 kg/m3, in contrast, specific gravity has no unit of measurement goes with it; nevertheless, although they don't have the same meaning, they have the same value because density of water is quite close to 1g/cm3.


i.e. 1 cm3 water weighs 1 g (as mentioned, density of water is 1g/cm3), and 1cm3 aluminum weighs 2.7 g (the density is 2.7 g/cm3), thus specific gravity of aluminum is 2.7 ÷ 1 = 2.7 (which has the same value with density)

Density of Plastics

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Plastic MaterialDensity(g/cm3) / Specific Gravity
ABS1.06
ABS Fire Retardant1.15 - 1.20
ABS High Heat1.10 - 1.15
ABS High Impact1.00 - 1.10
ABS/PC1.10 - 1.15
ABS/PC + 20% GF1.25
ABC/PC Fire Retardant1.17 - 1.19
AS1.08
ASA1.05 - 1.07
ASA/PC1.15
ASA/PC Fire Retardant1.25
ASA/PVC1.20
CA1.22 - 1.34
CAB1.15 - 1.22
CP1.17 - 1.24
COC1.01 - 1.03
CPVC1.50 - 1.55
ETFE1.70
EVA0.92 - 0.94
EVOH1.10 - 1.20
FEP2.10 - 2.20
HDPE0.94 - 0.97
HIPS1.03 - 1.06
LCP1.40
LCP + CF1.50
LCP + GF1.50 - 1.80
LCP + MF1.50 - 1.80
LDPE0.92 - 0.94
LLDPE0.92 - 0.95
MABS1.08
MDPE0.93 - 0.94
PA11 + 30% GF1.25 - 1.27
PA11 Conductive1.13
PA11-Flexible1.03 - 1.05
PA11-Rigid1.02 - 1.03
PA12 Conductive1.14
PA12 + GF1.22 - 1.42
PA12 - Flexible1.01 - 1.04
PA12 - Rigid1.01
PA461.17 - 1.19
PA46 + 30% GF1.42 - 1.44
PA61.12 - 1.14
PA6-101.09 - 1.10
PA661.13 - 1.15
PA66 + 30% GF1.37
PA66 + 30% MF1.35 - 1.38
PA66 IM1.05 - 1.10
PA66 IM + 15-30% GF1.25 - 1.35
PAI1.40
PAI + 30% GF1.60
PAI LOW FRICTION1.40 - 1.50
PAN1.10 - 1.15
PAR1.20 - 1.26
PAR + 30-60% GF1.43 - 1.77
PBT1.30 - 1.40
PBT + 30% GF1.50 - 1.60
PC1.20
PC + 20-40% GF1.35 - 1.52
PC + 20-40% GF FLAME RETARDANT1.40 - 1.50
PC HIGH HEAT1.15 - 1.20
PC/PBT1.17 - 1.30
PC/PBT + GF1.30 - 1.59
PCL1.14
PCTFE2.10 - 2.20
PE + 30% GF1.20 - 1.28
PE/TPS1.00 - 1.05
PEEK1.26 - 1.32
PEEK + 30% CF1.40 - 1.44
PEEK + 30% GF1.49 - 1.54
PEI1.27 - 1.30
PEI + 30% GF1.50 - 1.60
PEI + MF1.40 - 1.50
PEKK LOW CRYSTALLINITY GRADE1.27 - 1.28
PESU1.37 - 1.46
PESU + 10-30% GF1.50 - 1.60
PET1.30 - 1.40
PET + 30% GF1.50 - 1.60
PET + 30/35% GF IM1.50
PETG1.27 - 1.38
PFA2.1 - 2.2
PGA1.40 - 1.60
PHB1.30 - 1.50
PI1.31 - 1.43
PLA1.23 - 1.25
PLA FIBER MELT SPINNING1.23 - 1.25
PLA INJECTION MOLDING1.24 - 1.26
PMMA1.17 - 1.20
PMMA HIGH HEAT1.15 - 1.25
PMMA IM1.23 - 1.25
PMP0.84
PMP + 30% GF1.05
PMP MF1.08 - 1.10
POM1.41 - 1.42
POM IM1.30 - 1.35
POM LF1.40 - 1.54
POM MF1.50 - 1.60
PP Copolymer0.90 - 0.91
PP Homopolymer0.90 - 0.91
PP + 10-20% GF0.97 - 1.05
PP + 10-40% MF0.97 - 1.25
PP + 10-40% TF0.97 - 1.25
PP + 30-40% GF1.10 - 1.23
PP IM0.88 - 0.91
PPA1.11 - 1.20
PPA + 33% GF1.40 - 1.50
PPA + 45% GF1.58 - 1.60
PPE1.04 - 1.10
PPE + 30% GF1.26 - 1.28
PPE FR1.06 - 1.10
PPE IM1.00 - 1.10
PPE MF1.20 - 1.25
PPS1.35
PPS + 20-30% GF1.40 - 1.60
PPS + 40% GF1.60 - 1.70
PPS CONDUCTIVE1.40 - 1.80
PPS + GF or MF1.80 - 2.00
PPSU1.29 - 1.30
PS1.05
PS Crystal1.04 - 1.05
PS + 30% GF1.25
PS HIGH HEAT1.04 - 1.05
PSU1.24 - 1.25
PSU + 30% GF1.40 - 1.50
PSU MF1.50 - 1.60
PTFE2.10 - 2.20
PTFE + 25% GF2.20 - 2.30
PU1.11-1.24
PVC PLASTICIZED1.30 - 1.70
PVC RIGID1.35 - 1.50
PVC + 20% GF1.45 - 1.50
PVDC1.60 - 1.75
PVDF1.70 - 1.80
SAN1.06 - 1.10
SAN + 20% GF1.20 - 1.40
SMA1.05 - 1.08
SMA + 20% GF1.20
SMA FR V01.20
SMMA1.05 - 1.13
SRP1.19 - 1.21
TPE1.15 - 1.24
TPS INJECTION MOULDING1.40 - 1.65
TPS WATER RESISTANT1.34 - 1.38
UHMWPE0.93 - 0.95
XLPE0.92 - 1.40

Remarks: Glass Fiber (GF), Carbon Fiber (CF), Mineral Fiber (MF), Impact Modified (IM), Low Friction (LF), Talc Filled (TF), Ultra High Molecular Weight Polyethylene (UHMWPE), Crosslinked Polyethylene (XLPE)

Density of Chemical Additives for Injection Molding

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AddictiveDensity (g/cm3) / Specific Gravity
Glass Fiber (GF)2.54
Tale2.8
Carbon Fiber (CF)2.7
Mica2.6 - 3.8


Due to the different density of plastic, we can easily identify different plastics by "Buoyancy Test", for more information, please check out in related articles.

★ Related articles:  Easy for Beginner: Plastic Material Identification by Buoyancy Test
 How to Identify Plastic Materials by Burn Test Accurately
 Plastic Material:Moisture Absorption

 


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