Polyme Analysis 2010 Part 4 pot

üThe parameters for this test are : +The support span; +The speed of the loading +The maximum deflection for the test.. These parameters are based on the test specimen thickness, and are

ü Most commonly the specimen lies on a span and the load is applied to the center by the loading nose producing three point bending at a specified rate

üThe parameters for this test are :

+The support span;

+The speed of the loading +The maximum deflection for the test

These parameters are based on the test specimen thickness, and are defined differently by ASTM and ISO

Specimen Size: üA variety of specimen shapes can be used

üThe most commonly used specimen size:

+ 3.2mm x 12.7mm x 125mm for ASTM D790 +10mm x 4mm x 80mm for ISO 178

Test Procedure:

Flexural test

üFlexural strength

üFlexural modulus

Flexural test

b b

L

F

δ

3

3

4 h b

L m

E b =

2 2

3

h b

L F

b =

σ

m : initial slope of the load vs deflection curve

For relatively thin samples → two point loading

For thick samples → 4 point loading

Flexural test

Izod Impact Testing (Notched Izod)

üNotched Izod Impact is a single point test that measures

a materials resistance to impact from a swinging

pendulum

ü Izod impact is defined as the kinetic energy needed to

initiate fracture and continue the fracture until the

specimen is broken

üIzod specimens are notched to prevent deformation of

the specimen upon impact

üThis test can be used as a quick and easy quality control check to determine if a material meets specific impact

properties or to compare materials for general toughness

Scope:

ü 64 x 12.7 x 3.2 mm for ASTM D256

üThe preferred thickness is 6.4 mm because it is not as likely to bend or crush

üThe depth under the notch of the specimen is 10.2 mm

ü80 x 10 x 4 mm for ISO 180

üThe depth under the notch of the specimen is 8mm

Specimen Size:

Izod Impact Testing (Notched Izod)

üThe specimen is clamped into the pendulum impact test

fixture with the notched side facing the striking edge of the

pendulum

üThe pendulum is released and allowed to strike through

the specimen

üIf breakage does not occur, a heavier hammer is used

until failure occurs

üSince many materials (especially thermoplastics) exhibit

lower impact strength at reduced temperatures ⇒ to test

materials at temperatures that simulate the intended end

use environment

izodimpact.wmv

Izod Impact Testing (Notched Izod)

Test Procedure:

üThe specimens are conditioned at the specified temperature in a freezer until they reach equilibrium.

üThe specimens are quickly removed, one at a time, from the freezer and impacted.

üNeither ASTM nor ISO specify a conditioning time or elapsed time from freezer to impact - typical values from other specifications are 6 hours of conditioning and 5 seconds from freezer to impact.

Reduced Temperature Test procedure:

üImpact energy is expressed in J/m or ft-lb/in.

üImpact strength is calculated by dividing impact energy in J (or ft-lb) by the

thickness of the specimen.

üThe test result is typically the average of 5 specimens.

ISO

üImpact strength is expressed in kJ/m2

üImpact strength (acU) is calculated by dividing impact energy in J by the

area under the notch.

Data

3

b h

b = width of the sample

h = thickness of the sample

üThe test result is typically the average of 10 specimens.

The higher the resulting number, the tougher the material.