Polyme Analysis 2010 Part 2 docx

What are our expectations of polymer materials?• Excellent Characteristics: Mechanical and Physical Properties Thermal Behaviour Surface and interface Characteristics Electrical and Opt

What are our expectations of polymer materials?

• Excellent Characteristics:

Mechanical and Physical Properties Thermal Behaviour

Surface and interface Characteristics

Electrical and Optical Properties

•Safe to use

•Light weight

•Reliable, durable

•Low cost

•Less adverse environmental impact

•Good resistance to environmental attacks

Mechanical Testing

of Polymers

Types of Mechnical Tests

Tensile test (a) Flexural test (d) (e) (f)

Compression test (b) Shear (g)

(h)

(i)

Impact test (h) (i)

üMeasure the force required to break a specimen and the extent to which the specimen stretches or elongates to that breaking point.

üProduce a stress-strain diagram, which is used to determine tensile modulus

üThe data is often used to specify a material, to design parts to withstand application force and as a quality control check of materials

üSince the physical properties of many materials (especially thermoplastics) can vary depending on ambient temperature ⇒ test materials at temperatures that

simulate the intended end use environment

Tensile test

Specimen Size:

üThe most common specimen for ISO 527 is the ISO 3167 Type 1A

üASTM D882 uses strips cut from thin sheet or film

*The multipurpose test specimen:

+150 mm long, +The center section: 10 mm wide *4 mm thick *80 mm long

Tensile test

A tensile dog bone specimen

b W

For the composite samples

Longitudinal test

Transverse test

Test Procedure:

üSpecimens are placed in the grips and pulled until failure üFor ASTM D638, the test speed is determined by the material specification

üFor ISO 527 the test speed

is typically 5 or 50mm/min for measuring strength and elongation

+and 1mm/min for measuring modulus

ü An extensometer is used to determine elongation and tensile modulus

Tensile test

Tensile2.wmv