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Structure - Processing Linkages in

Polyethylene

David BroughAbhiram Kannan

Final Presentation ME 8883

Outline

‣ Motivation & Objective

‣ X Ray Scattering Datasets of Polyethylene

‣ Workflow

‣ Results and Discussions

‣ Future Work

‣ Summary

‣ Acknowledgements

Motivation

Jancar, J. et al. Current issues in research on structure - property relationships in polymer nanocomposites. Polymer 51, 3321–3343 (2010)

Hierarchical structural assembly of a material influences the properties on the macroscopic scale

Motivation & Objective

Processing Condition a

Processing Condition b

Microstructure Set a

Microstructure Set b

Properties Set a

Properties Set b

PE

Temperature Pressure

Isotropic vs Anisotropic Homogeneous vs Heterogeneous

Yield Strength

Polyethylene (PE)

X Ray Scattering Data of PESmall Angle X Ray Scattering (SAXS) data is related to spatial statistics

200 µm x 200 µm

Lamella

Inter Crystalline Amorphous

~10 nm

X Rays

Play

Film sample is strained continuously while being probed by X rays

X Ray Scattering Data of PE

X Rays

Bulk Density Processing Condition Film Thickness (µm)

0.912 gms/cc1 20 30 752 20 30 75

0.923 gms/cc1 20 30 752 20 30 75

Workflow

spatial statistics

dimensionality reduction

processing linkage

SAXS Data

Principal Components

Analysis (PCA)

Transfer Function

Model (TFM)

Principal Components Analysis

• 3200 .tif images across 12 samples (~250 per sample) • Log intensity scaled by mean to account for thickness effects • Scaled images fed to PCA Algorithm • Outputs of PCA Algorithm visualized in D3

Compare :-

1. Effects of Processing Conditions 2. Effects of Density 3. Effects of Thickness

Transfer Function Model Linkage

• For sample 6,10 each Principal Component is fit to a Transfer Function model of order (2,1,5)

• Using obtained coefficients, predictions for the remaining samples are made

• Comparison of Predicted and True Low Dimensional Trajectories.

Model Equation:-

Xt = a1Xt−1 + a2Xt−2 + b0ε t + b1ε t−1 + b2ε t−2 + b3ε t−3 + b4ε t−4 + b5ε t−5 + Err

Summary

• Dimensionality Reduction of time resolved data by PCA • Objective comparison between strain derived microstructures of

PE • Minimization of User Bias incurred from traditional analysis

protocols • Applied method for deriving processing linkages via Transfer

Function Model might hold potential

Future Work

• Extraction of spatial statistics by via transformation of SAXS data

• Reconstruction of 2 Phase Crystalline - Amorphous Microstructures

• Extend Transfer Function Model to incorporate Stress Values • Property Linkage with Crystallinity, Orientation etc. • Additional Length Scales (~0.1 nm) from Wide Angle Scattering

Data (WAXS)

Acknowledgements

• Dr. Surya Kalidindi (GT) • Dr. Hamid Garmestani (GT) • Dr. Tony Fast (GT) • Dr. David Bucknall (GT) • Dr. David Fiscus (ExxonMobil)