Molecular Structure
The physical and even the chemical properties of a polymer in a final manufactured product can be closely related to the polymer structure.
Types of polymer structure:
- Linear
- Random branched
- Comb structure
- Starburst polymers or dendrimers
- Copolymers
- Cross-linked
Multi-detector SEC, such as the TDA, can be used to determine a number of the factors that determine structure:
- Branching ratio
- Branching frequency
- Molecular density / Intrinsic Viscosity
- Copolymer composition
- Backbone modification
Structure is determined using a combination of an intrinsic viscosity detector that is sensitive to density, and a light scattering detector that provides molecular weight. These parameters are used to construct a Mark – Houwink plot from which a range of structural information can be deduced.
Application example:
Acrylonitrile-butadiene copolymers, commonly called nitrile rubbers (NBR), are used widely for adhesive compounding, and gloves used for examination and cleaning.
The composition of the copolymers, the polymer cross-linking and branching as well as the molecular weight of NBR affect the macroscopic properties of NBR such as flexibility and puncture resistance.
