Thermal Analysis of Thermosets Noah Menard Veritas Testing and Consulting, LLC Denton, TX

Thermosets and Thermal Analysis 4 Feb 2015©Veritas Testing and Consulting. LLC2 TechniqueUncured SamplesCured SamplesUncommon Methodology DSCTime and how energetic a cure. Time/temperature/ degree of cure relationships Glass transition temperature Residual cure MT-DSC Fast Scan DSC UV-DSC TGAWeight loss on curingDecomposition temperatures Filler content Derivative controlled methods Hyphenated TGAWhat’s evolved on curingUnreacted components.TG-IR, MS, GCMS, etc TMAContraction on curingCTE on cured materialsDilatometry DMATime to gelation Re-vitrification Temperature Glass transition temperature Beta transition Strain and frequency scans Immersion/humidity tests

Differential Scanning Calorimetry (DSC) Looks at changes in a materials heat capacity. Detects energy released or absorbed. 4 Feb 2015©Veritas Testing and Consulting. LLC3

How much did it cure? 4 Feb 2015©Veritas Testing and Consulting. LLC4 Blue Curve = -126 J/g Green Curve = -191 J/g Degree of Cure (DC) = (1 – fraction uncured)100 Uncured Fraction = (Full Cure – unknown) Full Cure = ( )/-191 =.34 DC = (1-.34) = 66% ΔΗ = -126 ΔΗ = -191

So from the cure, we predict cure time 4 Feb 2015©Veritas Testing and Consulting. LLC5

Then on the reheat, 4 Feb 2015©Veritas Testing and Consulting. LLC6

Tracking Cures by Tg 4 Feb 2015©Veritas Testing and Consulting. LLC7

Now in real life The Tg can be hidden by residual curing or by stress relief 4 Feb 2015©Veritas Testing and Consulting. LLC8

MT-DSC – cleaning up the Tg and more 4 Feb 2015©Veritas Testing and Consulting. LLC9

TTT Diagrams 4 Feb 2015©Veritas Testing and Consulting. LLC10

Fast Scanning DSC 4 Feb 2015©Veritas Testing and Consulting. LLC11 Single run at 10 C/min

The high rates let us… 4 Feb 2015©Veritas Testing and Consulting. LLC12 See under the exotherm Makes transitions more visible

Linking Tg to chemistry of cure 4 Feb 2015©Veritas Testing and Consulting. LLC13 IR Scan of Epoxy over 3 Hour Period Epoxy at Specific Times

Thermogravimetric Analysis (TGA) 4 Feb 2015©Veritas Testing and Consulting. LLC14

TGA-IR or MS 4 Feb 2015©Veritas Testing and Consulting. LLC15 Best match: C 3 H 8 O 2 N 2 To MS A

Analysis by TG-IR in Action 4 Feb 2015©Veritas Testing and Consulting. LLC16

Thermomechanical Analysis (TMA) The Tg is a region (Mark) Tg from the three techniques do not match – DSC<TMA<DMA 4 Feb 2015©Veritas Testing and Consulting. LLC17 Temperature /K Expansion/(mm) T g = e-5/K 2.195e-2/K

CTE 4 Feb 2015©Veritas Testing and Consulting. LLC18

TMA - Dilatometry 4 Feb 2015©Veritas Testing and Consulting. LLC19 Dilatometer Al Sample TMA Probe

Dynamic Mechanical Analysis The dirty secret of DMA – most of them are used for Tg measurement 4 Feb 2015©Veritas Testing and Consulting. LLC20 tan  Temperature hours 1 hour Heat flow (mW) tan  Heat flow 20 C/min hours 500 C/min

DMA gives you modulus and viscosity in cure 4 Feb 2015©Veritas Testing and Consulting. LLC21

As well as Tg 4 Feb 2015©Veritas Testing and Consulting. LLC22

DMA – Strain, Frequency, other effects 4 Feb 2015©Veritas Testing and Consulting. LLC23

Immersion Testing 4 Feb 2015©Veritas Testing and Consulting. LLC24 Previous immersed & run in air Previous Immersed & run in salt water Failing Epoxy Marine Paint Never wet sample in air

Humidity 4 Feb 2015©Veritas Testing and Consulting. LLC25

Other things doable in a DMA 4 Feb 2015©Veritas Testing and Consulting. LLC26 Stress-strain Curves Creep-Recovery Tests Stress-Relaxation Frequency Scans Time Temperature Superposition Mastercurves Kinetics (Roller Model) UV curing

Thank you.