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Manipulation of Molecular Weight Distribution Shape as a New Strategy to Control Processing Parameters
Milena Nadgorny1, Dillon T Gentekos2, Zeyun Xiao1
1The Department of Chemical and Biomolecular Engineering, The University of Melbourne, Victoria, 3010, Australia.
Macromolecular Rapid Communications
|August 11, 2017
Summary
Altering the shape of polymer molecular weight distribution (MWD) significantly impacts material properties. Skewing MWD towards higher molecular weights enhances thermal stability, stiffness, and viscosity, offering new polymer engineering possibilities.
Area of Science:
- Polymer Science
- Materials Science
- Rheology
Background:
- Molecular weight and dispersity are key polymer properties influencing physical and rheological behavior.
- These parameters offer incomplete information regarding polymer composition, as reflected by molecular weight distribution (MWD) shape.
- Understanding MWD's influence is crucial for advanced polymer processing and material design.
Purpose of the Study:
- To investigate the impact of MWD symmetry on thermal and rheological properties of polymers.
- To demonstrate how controlled synthesis can manipulate MWD shape to engineer polymer characteristics.
- To correlate MWD asymmetry with specific material property changes.
Main Methods:
- Synthesis of polymers with identical average molecular weights and dispersity but varied MWD shapes.
- Characterization of thermal properties, including glass transition temperature (Tg).
- Rheological measurements to determine apparent viscosities and stiffness.
Main Results:
- Polymers with MWD skewed towards higher molecular weights exhibited elevated Tg.
- Increased stiffness and thermal stability were observed in polymers with higher molecular weight-skewed MWD.
- Higher apparent viscosities were recorded for polymers with MWD skewed to higher molecular weights.
Conclusions:
- MWD shape, not just average molecular weight and dispersity, significantly affects polymer properties.
- Controlled synthetic strategies can effectively tune MWD symmetry to engineer desired material performance.
- This approach provides a versatile method for tailoring polymer thermal and rheological characteristics.
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