Oligoisoprene additives for preventing and repairing polyethylene degradation during extrusion

Overview

Polyethylene degradation during extrusion is a persistent challenge in polymer manufacturing. The thermal and mechanical stresses of the extrusion process cause chain scission, generating radical species that trigger oxidation and fragmentation of polymer chains. This research proposes using oligoisoprene as molecular patches to inhibit radical propagation and repair damaged polyethylene chains during extrusion. Oligoisoprene's allylic protons are more stable than secondary alkyl protons, making them highly effective at halting radical-driven degradation. Unlike monomers, oligomers survive in the polymer melt at high temperatures, and their low molecular weight enhances compatibility with polyethylene. Isoprene is a biorenewable, non-hazardous resource, and the oligomerization process is scalable.

Technical specifications

Key features:

• Oligoisoprene additives interrupt radical propagation during polyethylene extrusion
• Allylic carbons in the oligoisoprene backbone react preferentially with radicals formed during chain scission
• Five well-controlled oligomers spanning molecular weights from 500 to 10,000 kDa will be synthesized via living polymerization
• Standard isoprene polymerization will be used to produce scalable oligomers for practical application
• Characterization employs dynamic mechanical testing, differential scanning calorimetry, and size exclusion chromatography
• Potential to repair aged polyethylene that has undergone degradation prior to extrusion
• Biorenewable, non-hazardous raw material with scalable oligomerization

Technology readiness level

This technology is at an early-to-mid stage of development. The research team has demonstrated expertise in oligomer synthesis through ring-opening metathesis polymerization and atom transfer radical polymerization, as well as in extruding polyethylene with functional additives. A prior study successfully extruded polyethylene with coconut oil to produce functional films for tropical fruit storage. The proposed one-year project encompasses oligomer synthesis, co-extrusion with polyethylene, comprehensive characterization, and assessment of repair capabilities for aged polyethylene. The goal is to establish correlations between oligomer molecular weight, oligomer concentration, and resulting polyethylene film properties.