Elongation at Break

1. What is elongation at break?
2. What is the formula of elongation at break?
3. What is the importance of elongation at break?
4. Which materials show high elongation?
5. What factors affect the elongation at break?
6. What are the test methods to calculate elongation?
7. Which instrument measures elongation at break?
8. What is the elongation at break values of several plastics?

What is elongation at break?

Elongation at Break is the ratio of the initial and final lengths of the plastic material before it breaks. This process takes place at a controlled temperature.

It is the ability of plastic material to resist changes in shape without cracking. It is also known as fracture strain or tensile elongation at break.

What is the formula of elongation at break?

The elongation is calculated as the relative increase in length.


Where:

• ɛ is the elongation
• ΔL is the final length
• L is the initial length

Elongation at Break is measured in % (% of elongation vs. initial size when break occurs). The maximum elongation at the break (Emax) is also called “strain to failure”.

What is the importance of elongation at break?

Elongation at Break is an important mechanical property of materials.

• It measures how much bending and shaping a material can withstand without breaking.
• It defines the ductility of a polymer.
• Used in components that absorb energy by plastic deformation.
• Used to screen materials for use as plastic hinges. High elongation at break is important for plastic hinges.

Which materials show high elongation?

Ultimate elongation values of several 100% are common for elastomers and film/packaging polyolefins. Rigid plastics, especially fiber-reinforced ones, often exhibit values under 5%. Fibers have a low elongation-to-break and elastomers have a high elongation at break.

The combination of high ultimate tensile strength and high elongation leads to materials of high toughness.

Materials that show high elongation are:

1. Thermoplastics with High Elongation – View Products
2. TPEs/TPVs with High Elongation – View Products
3. Rubbers with High Elongation – View Products
4. Thermosets with High Elongation – View Products

What factors affect the elongation at break?

• Velocity of Testing: Slow testing allows for polymer relaxation and higher elongation at break values.


• Orientation Level: Fibers that are less oriented tend to exhibit greater degrees of elongation at break.


• Temperature: In general, the elongation at break increases with an increase in temperature.


• Filler Content: The elongation at the break of composites decreases with an increase in the filler content.

What are the test methods to calculate elongation?

Tensile tests measure the force required to break a specimen. It also determines the extent to which the specimen stretches or elongates to that breaking point.

In general, “tensile test methods” measure the modulus of elasticity of materials. The common methods used are:

• ASTM D638 - Standard Test Method for Tensile Properties of Plastics
• ISO 527-1:2012 - Determination of tensile properties. General principles

These methods determine the tensile properties of plastics and plastic composites. This is done under defined conditions that can range from:

• pretreatment,
• temperature,
• humidity, and
• machine speed

The test specimens are in the form of a standard dumbbell shaped.

For ASTM D638, the test speed is determined by the material specification. For ISO 527, the test speed is typically 5 or 50 mm/min for measuring strength and elongation, and 1 mm/min for measuring modulus.

Apart from Elongation at Break, the tensile test results can also calculate:

• Tensile strength at yield
• Tensile strength at break
• Young's modulus
• Tensile modulus
• Strain
• Elongation and percent elongation at yield

Which instrument is used to determine elongation at break?

An extensometer determines the elongation and tensile modulus. It is a device that measures the changes in the length of an object. It evaluates the stress-strain curve values.

The two main types of extensometers are contact and non-contact.

1. Contact extensometers are further divided into two types:
   
   
   • Clip-on extensometer: They can measure displacements from very small to relatively large. That is from less than 1 mm to over 100 mm. Used for applications requiring high-precision strain measurement (most ASTM-based tests). Major advantages include:
     
     
     • Low cost
     • Easy to use
   
   
   • Automated testing clip-ons: They replace digital "sensor arm" extensometers. They can be applied to the specimen automatically by a motorized system. They produce much more repeatable results than traditional clip-on devices. They measure very high extensions (up to 1000 mm) without losing any accuracy. Major advantages include:
     
     
     • Better linearity,
     • reduced signal noise, and
     • synchronization with the corresponding force data.


2. Non-contact extensometers: These devices are beginning to bring advantages for certain applications. Especially, in industries where it is impractical to use contact extensometers.

What is the elongation at break values for several plastics?

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A-C     |      E-M     |      PA-PC     |      PE-PL     |      PM-PP     |      PS-X

Polymer Name	Min Value (%)	Max Value (%)
ABS - Acrylonitrile Butadiene Styrene	10.0	50.0
ABS Flame Retardant	2.0	80.0
ABS High Heat	2.0	100.0
ABS High Impact	2.0	100.0
ABS/PC Blend - Acrylonitrile Butadiene Styrene/Polycarbonate Blend	60.0	85.0
ABS/PC Blend 20% Glass Fiber	1.90	2.10
ABS/PC Flame Retardant	50.0	90.0
ASA - Acrylonitrile Styrene Acrylate	15.0	40.0
ASA/PC Blend - Acrylonitrile Styrene Acrylate/Polycarbonate Blend	25.0	50.0
ASA/PVC Blend - Acrylonitrile Styrene Acrylate/Polyvinyl Chloride Blend	40.00	70.00
CA - Cellulose Acetate	16.00	53.00
CAB - Cellulose Acetate Butyrate	40.00	90.00
Celllulose Diacetate-Pearlescent Films	25.00	45.00
Celllulose Diacetate-Gloss Film	25.00	45.00
Celllulose Diacetate-Integuard Films	5.00	15.00
Celllulose Diacetate-Matt Film	25.00	45.00
Cellulose Diacetate-Window Patch Film (Food Grade)	25.00	45.00
Cellulose Diacetate-Clareflect metallized film	30.00	50.00
Cellulose Diacetate-Colored Films	25.00	45.00
Cellulose Diacetate-Flame retardant Film	20.00	40.00
Cellulose Diacetate-High Slip Film	25.00	40.00
Cellulose Diacetate-Semitone Films	20.00	45.00
CP - Cellulose Proprionate	30.00	10.00
COC - Cyclic Olefin Copolymer	1.700	4.500
CPVC - Chlorinated Polyvinyl Chloride	23.00	50.00
ECTFE - Ethylene ChloroTriFluoroEthylene	250.00	325.00
ETFE - Ethylene Tetrafluoroethylene	100.00	300.00
EVA - Ethylene Vinyl Acetate	200.00	990.00
EVOH - Ethylene Vinyl Alcohol	180.00	350.00
FEP - Fluorinated Ethylene Propylene	250.00	300.00
HDPE - High Density Polyethylene	500.00	700.00
HIPS - High Impact Polystyrene	10.00	65.00
HIPS Flame Retardant V0	10.00	50.00
Ionomer (Ethylene-Methyl Acrylate Copolymer)	290.00	740.00
LCP - Liquid Crystal Polymer	1.00	3.00
LCP Carbon Fiber-reinforced	1.00	1.00
LCP Glass Fiber-reinforced	1.00	3.00
LCP Mineral-filled	2.00	5.50
LDPE - Low Density Polyethylene	200.00	600.00
LLDPE - Linear Low Density Polyethylene	300.00	900.00
MABS - Transparent Acrylonitrile Butadiene Styrene	12.00	20.00
PA 11 - (Polyamide 11) 30% Glass fiber reinforced	3.00	6.00
PA 11, Conductive	186.00	186.00
PA 11, Flexible	225.00	405.00
PA 11, Rigid	225.00	355.0
PA 12 (Polyamide 12), Conductive	186.00	186.00
PA 12, Fiber-reinforced	4.00	8.00
PA 12, Flexible	300.00	340.00
PA 12, Glass Filled	30.00	40.00
PA 12, Rigid	250.00	390.00
PA 46 - Polyamide 46	160.00	300.00
PA 46, 30% Glass Fiber	11.00	15.00
PA 6 - Polyamide 6	200.00	300.00
PA 6-10 - Polyamide 6-10	150.00	300.00
PA 66 - Polyamide 6-6	150.00	300.00
PA 66, 30% Glass Fiber	2.00	2.20
PA 66, 30% Mineral filled	2.00	45.00
PA 66, Impact Modified, 15-30% Glass Fiber	3.00	10.00
PA 66, Impact Modified	150.00	300.00
Polyamide 66 (Nylon 66), Long Glass Fiber, 40% Filler by Weight	2.00	2.00
Polyamide 66 (Nylon 66), Long Glass Fiber, 50% Filler by Weight	2.00	2.00
Polyamide 66 (Nylon 66), Long Glass Fiber, 60% Filler by Weight	2.00	2.00
Polyamide semi-aromatic	50.00	200.00
PAI - Polyamide-Imide	3.00	15.00
PAI, 30% Glass Fiber	6.00	7.00
PAI, Low Friction	7.00	9.00
PAN - Polyacrylonitrile	3.00	4.00
PAR - Polyarylate	50.00	100.00
PARA (Polyarylamide), 30-60% glass fiber	1.80	2.00
PBT - Polybutylene Terephthalate	5.00	300.00
PBT, 30% Glass Fiber	2.00	3.00
PC (Polycarbonate) 20-40% Glass Fiber	2.00	4.00
PC (Polycarbonate) 20-40% Glass Fiber Flame Retardant	2.00	4.00
PC - Polycarbonate, high heat	50.00	120.00
PC/PBT Blend - Polycarbonate/Polybutylene Terephthalate Blend	4.00	175.00
PC/PBT blend, Glass Filled	2.00	4.00
PCL - Polycaprolactone	600.00	900.00
PCTFE - Polymonochlorotrifluoroethylene	80.00	180.00
PE - Polyethylene 30% Glass Fiber	1.500	2.500
PE/TPS Blend - Polyethylene/Thermoplastic Starch	400.00	700.00
PEEK - Polyetheretherketone	30.00	150.00
PEEK 30% Carbon Fiber-reinforced	1.00	3.00
PEEK 30% Glass Fiber-reinforced	2.00	3.00
PEI - Polyetherimide	59.00	60.00
PEI, 30% Glass Fiber-reinforced	3.00	3.00
PEI, Mineral Filled	6.00	6.00
PEKK (Polyetherketoneketone), Low Cristallinity Grade	80.00	80.00
PESU - Polyethersulfone	10.00	80.00
PESU 10-30% glass fiber	2.00	6.00
PET - Polyethylene Terephthalate	30.00	70.00
PET, 30% Glass Fiber-reinforced	2.00	7.00
PET, 30/35% Glass Fiber-reinforced, Impact Modified	6.00	6.00
PETG - Polyethylene Terephthalate Glycol	50.00	50.00
PFA - Perfluoroalkoxy	300.00	300.00
PGA - Polyglycolides	15.00	20.00
PHB - Polyhydroxybutyrate	3.00	6.00
PHB-V (5% valerate)	5.00	10.00
PI - Polyimide	90.00	90.00
PLA - Polylactide	5.00	7.00
PLA, High Heat Films	179.00	181.00
PLA,injection molding	2.00	3.00
PMMA - Polymethylmethacrylate/Acrylic	2.00	10.00
PMMA (Acrylic) High Heat	2.00	10.00
PMMA (Acrylic) Impact Modified	4.00	70.00
PMP - Polymethylpentene	7.50	30.00
PMP 30% Glass Fiber-reinforced	2.00	3.00
PMP Mineral Filled	20.00	30.00
POM - Polyoxymethylene (Acetal)	15.00	75.00
POM (Acetal) Impact Modified	60.00	200.00
POM (Acetal) Low Friction	10.00	70.00
POM (Acetal) Mineral Filled	5.00	55.00
PP - Polypropylene 10-20% Glass Fiber	3.00	4.00
PP, 10-40% Mineral Filled	30.00	50.00
PP, 10-40% Talc Filled	20.00	30.00
PP, 30-40% Glass Fiber-reinforced	2.00	3.00
PP (Polypropylene) Copolymer	200.00	500.00
PP (Polypropylene) Homopolymer	150.00	60.00
PP Homopolymer, Long Glass Fiber, 30% Filler by Weight	2.00	2.00
PP Homopolymer, Long Glass Fiber, 40% Filler by Weight	2.00	2.00
PP Homopolymer, Long Glass Fiber, 50% Filler by Weight	2.00	2.00
PP, Impact Modified	200.00	700.00
PPA - Polyphthalamide	2.60	30.00
PPA – 30% Mineral-filled	1.10	1.30
PPA, 33% Glass Fiber-reinforced	2.00	2.20
PPA, 33% Glass Fiber-reinforced – High Flow	1.70	1.90
PPA, 45% Glass Fiber-reinforced	227.00	229.00
PPE - Polyphenylene Ether	45.00	60.00
PPE, 30% Glass Fiber-reinforced	3.00	3.00
PPE, Flame Retardant	30.00	50.00
PPE, Impact Modified	40.00	60.00
PPE, Mineral Filled	20.00	40.00
PPS - Polyphenylene Sulfide	1.00	4.00
PPS, 20-30% Glass Fiber-reinforced	1.00	2.00
PPS, 40% Glass Fiber-reinforced	1.00	2.00
PPS, Conductive	0.50	3.00
PPS, Glass fiber & Mineral-filled	1.000	3.00
PPSU - Polyphenylene Sulfone	30.00	90.00
PS (Polystyrene) 30% glass fiber	1.00	1.50
PS (Polystyrene) Crystal	1.00	4.00
PS, High Heat	1.00	4.00
PSU - Polysulfone	50.00	100.00
PSU, 30% Glass fiber-reinforced	2.00	3.00
PSU Mineral Filled	2.00	5.00
PTFE - Polytetrafluoroethylene	200.00	400.00
PTFE, 25% Glass Fiber-reinforced	100.00	300.00
PVC (Polyvinyl Chloride), 20% Glass Fiber-reinforced	2.00	5.00
PVC, Plasticized	100.00	400.00
PVC, Plasticized Filled	200.00	500.00
PVC Rigid	25.00	80.00
PVDC - Polyvinylidene Chloride	160.00	250.00
PVDF - Polyvinylidene Fluoride	50.00	300.00
SAN - Styrene Acrylonitrile	2.00	5.00
SAN, 20% Glass Fiber-reinforced	1.00	2.00
SMA - Styrene Maleic Anhydride	2.00	30.00
SMA, 20% Glass Fiber-reinforced	2.00	3.00
SMA, Flame Retardant V0	2.00	2.00
SMMA - Styrene Methyl Methacrylate	2.10	52.00
SRP - Self-reinforced Polyphenylene	6.00	10.00
TPS/PE BLend - Thermoplastic Starch/ Polyethylene Blend (30 micron films tested)	300.00	350.00
TPS, Injection General Purpose	25.00	135.00
TPS, Water Resistant	2.00	2.00
UHMWPE - Ultra High Molecular Weight Polyethylene	200.00	500.00
XLPE - Crosslinked Polyethylene	10.00	440.00