Moisture-Driven Degradation Mechanisms in the Viscoelastic Properties of TPU-Based Syntactic Foams

TL;DR

This study investigates how long-term moisture exposure affects the chemical, morphological, and viscoelastic properties of TPU-based syntactic foams, revealing degradation mechanisms relevant for their durability in various applications.

Contribution

It provides a multi-scale analysis of moisture-induced degradation mechanisms in TPU syntactic foams, addressing a gap in understanding their long-term durability.

Findings

Moisture exposure causes chemical and morphological changes in TPU foams.

Microphase morphological changes correlate with alterations in viscoelastic properties.

Volume fraction of glass microballoons influences moisture degradation effects.

Abstract

Syntactic foams have found widespread usage in various applications including, marine, aerospace, automotive, pipe insulation, electrical cable sheathing, and shoe insoles. However, syntactic foams are often exposed to moisture when used in these applications that potentially alter their viscoelastic properties, which influences their long-term durability. Despite their significance, previous research has mainly focused on experimental studies concerning mechanical property changes resulting from filler loading and different matrix materials, overlooking the fundamental mechanisms resulting from moisture exposure. The current paper aims to bridge this gap in knowledge by elucidating the impact of long-term moisture exposure on TPU and TPU-based syntactic foam through multi-scale materials characterization approaches. Here, we choose a flexible syntactic foam manufactured using thermoplastic polyurethane elastomer (TPU) reinforced with glass microballoons (GMB) through selective laser sintering. Specifically, the research investigates the influence of moisture exposure time and the volume fraction of GMB on chemical and microphase morphological changes, along with their associated mechanisms. The study further examines how these microphase morphological changes manifest in viscoelastic properties.