# Ethylene-Vinyl Acetate Copolymer as a Polyfunctional Modifier for Low-Viscosity Photosensitive Compositions

## TL;DR

This study explores using heat-treated EVA as a modifier in 3D printing materials to improve their properties at low temperatures.

## Contribution

The paper introduces EVA as a polyfunctional modifier that can act as a thickener but not as a crosslinking agent in photosensitive compositions.

## Key findings

- Heat-treated EVA forms C=C bonds, enabling it to act as a crosslinking agent with tBA.
- EVA changes the flow behavior of the composition from Newtonian to pseudoplastic with increasing concentration.
- EVA cannot simultaneously function as a crosslinking agent due to a heterogeneous phase structure.

## Abstract

The article presents the results of a study of the possibility of using heat-treated ethylene-vinyl acetate copolymer (EVA) as a thermoplastic modifier in a photosensitive composition based on tert-butyl acrylate (tBA). The use of such a modifier in 3D printing compositions is important for improving their physical and mechanical properties at low temperatures. An attempt was also made to use EVA as a polymer chain brancher. The molecular structure of the components and their compositions, rheology, curing kinetics, and phase organization of photocured systems were studied using FTIR and NMR spectroscopy, spectrophotometry, rheometry, Photo-DSC, and scanning electron microscopy. It was found that heat treatment of EVA allows the formation of single C=C bonds in macromolecules, which are necessary for a potential crosslinking agent with tBA. It was shown that EVA effectively functions as a thickener and modifier: with an increase in the modifier concentration, the nature of the composition flow changes from Newtonian to pseudoplastic, the rate of the photochemical polymerization reaction decreases, and the degree of conversion of the system decreases. However, the formation of a heterogeneous phase structure and the absence of a continuous spatial network of chemical bonds prevent the use of EVA simultaneously as a functional additive and crosslinking agent.