307 - Polymer Analysis

Gel Permeation Chromatography (GPC)

A technique used to separate polymer molecules according to their hydrodynamic size and determine molecular-weight information.

Size Exclusion Chromatography (SEC)

A technique that separates dissolved polymer molecules according to size.

Retention time

Time required for a molecule to pass through the chromatography system.

Mark-Houwink relationship

Relationship connecting intrinsic viscosity and molecular weight using polymer-specific constants.

Thermal analysis

Analysis of changes in a material property as temperature changes.

Differential Thermal Analysis (DTA)

Measures the temperature difference between a sample and reference during a controlled thermal programme.

DTA endotherm

A thermal event where the sample absorbs heat.

DTA exotherm

A thermal event where the sample releases heat.

Differential Scanning Calorimetry (DSC)

Measures the heat flow required to maintain a sample and reference at the same temperature.

DSC endotherm

Heat-absorbing event such as melting.

DSC exotherm

Heat-releasing event such as crystallisation or curing.

DSC melting peak

Endothermic peak associated with melting crystalline regions.

DSC crystallisation peak

Exothermic peak associated with crystallisation.

DSC curing peak

Exothermic peak associated with a curing reaction.

DSC memory effect

The effect of previous thermal history on subsequent DSC behaviour.

Thermogravimetric Analysis (TGA)

Measures changes in sample mass as temperature changes.

TGA thermal stability

Ability of a material to resist decomposition or mass loss during heating.

TGA mass loss

Reduction in sample mass due to processes such as evaporation, decomposition or oxidation.

Thermomechanical Analysis (TMA)

Measures dimensional changes in a sample under a static load as temperature changes.

TMA thermal expansion

Measurement of dimensional changes caused by temperature.

TMA softening

Measurement of deformation as the material softens with increasing temperature.

TMA deflection

Measurement of deformation under an applied load as temperature changes.

Shear rate

Rate at which adjacent layers of material move relative to each other.

Shear thinning

Decrease in viscosity as shear rate increases.

Low shear rate

A condition where polymer viscosity is generally higher.

High shear rate

A condition where polymer chains orient and slide more easily, reducing viscosity.

Tensile test

Test where a specimen is pulled while force and deformation are measured.

Creep test

Test measuring strain over time under constant stress.

Stress relaxation test

Test measuring stress over time under constant strain.

DMA test

Test measuring dynamic viscoelastic properties.

Fracture test

Test used to investigate crack initiation and propagation.

Fatigue test

Test involving repeated cyclic loading to determine fatigue behaviour.

Impact test

Test involving rapidly applied loading to assess impact resistance.