Thermal and Mechanical Analysis

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Thermal and Mechanical Analysis
CNMR Athlone Institute of Technology
Alan Murphy
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Introduction
CNMR Athlone Institute of Technology

• Plastic materials are tested throughout their
  life
• Monomer / Reactants
• Polymer / Raw Material Additives
• Product / Design
• Product / Research Development
• Processing / Quality Control
• Product / Service
• Product / End of Life

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Introduction
CNMR Athlone Institute of Technology

• A knowledge of available test methods is useful
  to
• Identify Research Development requirements
• Control incoming raw material quality
• Quantify product specifications
• Understand material data sheets
• Correct manufacturing problems
• Investigate customer complaints
• Continuously improve the product

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Introduction
CNMR Athlone Institute of Technology

• Raw Material Testing
• Control of raw material helps to assure
  consistent processing and end product
  characteristics.
• Melt Flow Rate and Density are the most common
  raw material tests but other raw material tests
  may be specified if warranted by the product.
• Eg.1 Impact test for safety glasses.
• Eg.2 GPC for molecular weight control
• Eg 3. TGA to measure glass content

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Introduction
CNMR Athlone Institute of Technology

• Testing during processing
• QC tests, such as weight or moisture content
• Troubleshooting tests, such as investigating
• Why a component is cracking during assembly
• Why an extruded tube is shrinking after
  manufacture
• Where contamination is coming from what type

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Introduction
CNMR Athlone Institute of Technology

• Testing during service
• Research and Development tests, such as
  comparison of alternative materials or property
  loss with time.
• Customer complaints.
• eg Why has the product failed after 3 months
  use ?
• Why has the product embrittled ?
• Why has discolouration occurred ?

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Thermal Analysis
CNMR Athlone Institute of Technology

• ANALYTICAL TECHNIQUES
• Differential Scanning Calorimetry (DSC)
• Dynamic Mechanical Thermal Analysis (DMTA)
• Thermogravimetric Analysis (TGA)
• Melt Flow Rheology (MFI)
• Gel Permeation Chromatography (GPC)

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Thermal Analysis
CNMR Athlone Institute of Technology

• Differential Scanning Calorimetry (DSC)

DSC is a thermal method of analysis to study the
thermal behaviour and thermal properties of
materials (typically polymers). The material is
sealed in a sample pan and subjected to a
controlled temperature programme. The resulting
thermograph can yield much valuable information
about the properties of the material analysed.

• Main use of DSC Material Identification (Tm and
  DHf) based on IS EN ISO 31462000 Method C2

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Thermal Analysis
CNMR Athlone Institute of Technology

• Differential Scanning Calorimetry (DSC)

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Thermal Analysis
CNMR Athlone Institute of Technology

• Differential Scanning Calorimetry (DSC)

• Other uses of DSC
• Crystallinity determination by DSC (based on IS
  EN ISO 31462000 Method C2).
• Purity and Polymorphism analysis by DSC.
• Thermal Stability of materials (e.g. oxidative
  induction time (OiT) of materials) by DSC.

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Thermal Analysis
CNMR Athlone Institute of Technology

• Differential Scanning Calorimetry (DSC)

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Thermal Analysis
CNMR Athlone Institute of Technology

• Dynamic Mechanical Thermal Analysis (DMTA)

Dynamic Mechanical Thermal Analysis (DMTA)
records the temperature-dependent visco-elastic
properties and determines the modulus of
elasticity and the damping values by applying an
oscillating force to the sample. Thermal method
of analysis used to determine thermo-mechanical
properties of materials (i.e. Glass Transition
Temperature Tg). Used as an alternative to DSC
which is typically estimating Tg. Used to more
accurately determine the Tg value, strength and
temperature-dependant elongation of a material.
in several modes
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Thermal Analysis
CNMR Athlone Institute of Technology

• Thermogravimetric Analysis (TGA)

TGA measures the weight of a substance heated at
a controlled rate as a function of temperature or
time. All materials ultimately decompose on
heating, and the decomposition temperature and
profile is a characteristic property of each
material.

• Main use of TGA Inorganic Content of Material

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Thermal Analysis
CNMR Athlone Institute of Technology
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Thermal Analysis
CNMR Athlone Institute of Technology

• Thermogravimetric Analysis (TGA)

• Other uses of TGA
• Material Thermal Stability.
• Moisture and Volatiles Content (TG-IR).
• Composition of Multi-Component Systems.
• Shelf-Life Studies and Decomposition Kinetics.

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Thermal Analysis
CNMR Athlone Institute of Technology

• Thermogravimetric Analysis (TGA)

Polymer 64.4
Carbon Black 3.4
Glass Fibre 32.2
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Rheological Analysis
CNMR Athlone Institute of Technology

• Melt Flow Rate (MFR) to ISO 1133.
• Grams of material that flow through a simple die
  in 10 minutes using a loaded piston and a set
  temperature.
• Is a measure of Shear Viscosity and is directly
  proportional to the average molecular weight.
• Uses Raw material control processing quality
  regrind studies useful troubleshooting test

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CNMR Athlone Institute of Technology
Rheological Analysis

• Capillary Rheometry uses motor driven pistons to
  produce high pressures and two barrels with dies
  to
• measure shear viscosity and elongational
  viscosity.
• Mimics processing conditions gives information
  on average molecular weight and molecular weight
  distribution.
• Uses mould and die design new material
  validation troubleshooting raw material control

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CNMR Athlone Institute of Technology
Mechanical Analysis

• Tensile Testing to ISO 527
• Measures the strength of a material and its
  flexibility (elongation).
• Also used to measure peel strength, bond
  strength, weld strength.
• Carried out on dumbbell specimens or actual
  product.
• Uses QC control for material or product

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CNMR Athlone Institute of Technology Impact
Analysis

• Izod and Charpy Impact Testing to ISO 179/180.
• These are pendulum impact tests generally done on
  test bars but can be adapted for small products.
• Usually notched, testing can be done at ambient
  or sub-zero temperatures.
• Uses QC test, material comparison, notch
  sensitivity

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CNMR Athlone Institute of Technology Aging
Studies

• Use of elevated temperatures to accelerate the
  aging process of plastic products.
• Based on a 10ºC rise in environmental temperature
  produces a twofold increase in the degradation
  rate.
• Humidity can be applied too if considered a
  factor.
• Uses shelf-life studies product data regrind
  analysis and the affect of other influences on
  product lifespan

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Chemical Analysis
CNMR Athlone Institute of Technology

• Gel Permeation Chromatography (GPC)

GPC causes separation by various pore sizes in
the column packing material, separating on the
basis of molecular size, not molecular
weight. Main use of GPC (or SEC) Measuring
average molecular weight (Mp) and molecular
weight distribution (Mw) of a material. Typical
Detection methods used are UV-vis and Refractive
Index.
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Chemical Analysis
CNMR Athlone Institute of Technology

• Gel Permeation Chromatography (GPC)

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Case Study A
CNMR Athlone Institute of Technology

• Contamination Issue

The client sent one sample of their product with
particulate on the bottom of the container.
How was it resolved?

• Specimens were isolated and cleaned in Class 100
  Cabinet

• FTIR and DSC were applied to determine the
  material types

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Case Study A
CNMR Athlone Institute of Technology

• Contamination Issue

Isolated White Particulate Matter FTIR
Polytetrafluoroethylene (PTFE)
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Case Study A
CNMR Athlone Institute of Technology

• Contamination Issue

Isolated White Particulate Matter DSC Tm
329oC
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Case Study A
CNMR Athlone Institute of Technology

• Outcome

The client checked their materials list and
equipment associated with this product.
The PTFE Source was determined to have come from
a stirring bar used during manufacture of the
solution.
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Case Study B
CNMR Athlone Institute of Technology

• Processing Issue

A batch of parts were cracking in service after
normal pressure was put on the end of the part.
How was it resolved?

• GPC was used to compare both good and bad
  samples.

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Case Study B
CNMR Athlone Institute of Technology

• Processing Issue

Therefore we looked at the process and decided to
look at the moisture content of the pre-processed
material

• Using Karl Fischer Coulometry we determined that
  the material had not been dried sufficiently.

• This then led to the materials molecular weight
  being affected during processing causing the
  material in the part to be weakened.

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Case Study C
CNMR Athlone Institute of Technology

• Recycling Issue

• A manufacturer using regrind polyethylene
  material experienced difficulties with
  contamination of screen plates within an
  extruder.
• The problem was thought to be caused by
  contamination of the regrind feedstock. CNMR were
  requested to
• (1) Identify the contaminant
• (2) Determine the source of contamination if
  possible

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Case Study C
CNMR Athlone Institute of Technology

• Recycling Issue

• Debris from the screen plates was examined under
  an optical microscope. It was determined that the
  contamination was not compatible with the matrix
  and could be removed easily.

• FTIR determined that the materials present were
  PET-based.

PET
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Case Study C
CNMR Athlone Institute of Technology

• Recycling Issue

DSC confirmed that the contamination had a Tm at
ca. 250oC. This is typical of the melting
characteristics demonstrated by PET.
Material from two silos were analysed. The
granules were separated simply according to
density. Only one material from one of the silos
was found to contain dense particles. These
particles had the same thermal characteristics as
the contaminant.
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THANK YOU...
CNMR Athlone Institute of Technology
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CNMR Athlone Institute of Technology
Contact DetailsMr. Mark Atterbury Mr. Alan
MurphySenior Research Officer Senior Research
OfficerTel 00353 9064 83070 00353 9064
42575Email matterbury_at_ait.ie amurphy_at_ait.ie