Characterization of an Poly(ethylene-vinyl acetate) Copolymer

Importance of the Topic

Ethylene-vinyl acetate copolymers combine the properties of polyethylene and vinyl acetate to produce materials with tunable flexibility, adhesion, and resistance to heat and weather. Accurate determination of molecular weight distribution and composition is essential for quality control and performance optimization in applications such as sealants, foils, impact modifiers, and rubber additives.

Objectives and Study Overview

This application note demonstrates a gel permeation chromatography method for characterizing the molecular weight distribution of ethylene-vinyl acetate copolymers. The goal is to establish reliable conditions for separation, calibration, and data evaluation to support routine analysis and product development.

Methodology

A statistical copolymer of ethylene and vinyl acetate was analyzed by size exclusion chromatography using the following conditions

• Mobile phase tetrahydrofuran at a flow rate of 0.75 mL per minute and 25 degrees Celsius
• PSS SDV columns selected according to target molecular weight range
• Sample concentrations adjusted based on polymer dispersity and molar mass
• Injection volume of 100 microliters

Used Instrumentation

• High performance liquid chromatography system equipped with PSS SDV column set
• Refractive index detector Shodex RI71
• Calibration with polystyrene standards using the ReadyCal Kit
• Data processing software PSS WinGPC

Main Results and Discussion

The method produced clear chromatograms and reliable molar mass distributions for EVA samples. Calibration against polystyrene standards allowed determination of number average and weight average molecular weights and polydispersity indices. The selection of column sets enabled baseline separation across low, medium, high, and ultrahigh molecular weight fractions.

Benefits and Practical Application of the Method

• Robust routine analysis for quality control in polymer manufacturing
• Ability to tailor column selection and sample preparation to specific molecular weight ranges
• Enhanced control over polymer performance parameters such as flexibility, adhesion, and resistance properties

Future Trends and Possibilities for Use

Advances in multidetector SEC, such as coupling with light scattering or viscometry, will improve absolute molar mass and compositional analysis. Development of alternative solvents and high-temperature chromatography could expand the range of analyzable copolymers. Integration with inline composition detectors may enable simultaneous determination of vinyl acetate content.

Conclusion

The described GPC method offers a reliable approach for characterizing ethylene-vinyl acetate copolymers. Its adaptability, precision, and straightforward calibration make it suitable for both research and industrial quality control.

References

• Agilent Technologies Column Application Note 10084 Characterization of a Polyethylene-Vinyl Acetate Copolymer July 1 2023