Compostable, fully biobased foams using PLA and micro cellulose for zero energy buildings

Area of Science:

• Materials Science
• Sustainable Building Materials
• Polymer Foams

Background:

• Growing demand for eco-friendly building materials due to environmental and health concerns.
• Need for bio-resourced alternatives to conventional insulation foams like polyurethane.
• Polylactic acid (PLA) and micro cellulose fibrils (MCF) as promising bio-based components.

Purpose of the Study:

• To investigate the production and properties of PLA/MCF bio-foams using supercritical CO2 (sc-CO2) foaming.
• To evaluate the impact of MCF concentration on foam structure, mechanical, thermal, and biodegradation properties.
• To assess the energy performance of these bio-foams in a net-zero energy model house.

Main Methods:

• Supercritical CO2 (sc-CO2) physical foaming of melt-mixed PLA and MCF systems.
• Characterization of foam structure (porosity, density, cell size) using Scanning Electron Microscopy (SEM).
• Assessment of mechanical properties, thermal conductivity, glass transition temperature (Differential Scanning Calorimetry - DSC), and biodegradability (compostability tests).

Main Results:

• MCF concentration influenced foam structure: initial increase then decrease in open porosity, higher density, reduced expansion, and smaller cell size.
• MCF addition decreased PLA's glass transition temperature, leading to thinner cell walls and initially improved mechanical and thermal insulation properties.
• PLA/MCF foams demonstrated enhanced compostability, with a maximum mineralization of 95% for 3 wt.% MCF foam.
• Energy simulations indicated a minimal increase (≤12%) in heating/cooling demand compared to polyurethane insulation, with best efficiency at low MCF fractions.

Conclusions:

• PLA/MCF bio-foams produced via sc-CO2 foaming are viable sustainable alternatives for building insulation.
• Optimizing MCF content is crucial for balancing structural, mechanical, thermal, and biodegradation performance.
• These bio-foams show promising energy efficiency in building applications, especially at lower MCF concentrations.