LLDPE Nanocomposites

Abstract

With limited circularity of plastics, the transition to recycled materials is crucial. For single-use products, such as packaging films, there is great potential to employ post-consumer recycled (PCR) plastic, but it faces challenges because of inconsistencies in material quality and mechanical properties. PCR films can, for example, contain ’gels’, that is, any small defects that distort the films. This thesis aims to investigate the limitations associated with PCR linear low-density polyethylene (LLDPE) and evaluate the potential of functionalized graphene to enhance the prop erties of LLDPE by making nanocomposites.

Microscopy, thermal, and rheological analysis, among others, were utilized to un derstand the material properties. These methods provided insights into batch vari ability, contamination levels, gel content, and the structural impact of incorporating functionalized graphene.

Characterization revealed significant batch-to-batch variability in PCR LLDPE and showed that PCR and virgin LLDPE had considerable differences, such as rheological behavior. Microscopy analyses of films identified two types of gel: small crosslinked gels present in both virgin and PCR materials, and larger fibrous gels found exclusively in PCR films, indicating contamination challenges inherent to re cycling processes. Incorporating functionalized graphene had varied effects on the material properties: It slightly decreased the thermal stability, while the influence on viscoelastic properties was complex and dependent on graphene type and con centration. However, thermal transitions such as melting and crystallization were not affected, suggesting that large-scale processing will not be significantly affected. The dispersion of functionalized graphene within the nanocomposites was lower than that desired, potentially influencing the observed viscoelastic properties.

In conclusion, this work has highlighted the complexity inherent in PCR materials and demonstrated the potential of using different functionalizations to fine-tune vis coelastic and mechanical properties in LLDPE nanocomposites, suggesting promis ing pathways toward improving the quality and application potential of recycled polymer systems.