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

Kayode Oluwabunmi,Nandika Anne D’Souza,Thomas Theyson,Tae-Youl Choi,Weihuan Zhao

doi:10.1038/s41598-020-74478-y

Kayode Oluwabunmi, Nandika Anne D’Souza + Show 3 more

Open Access

https://doi.org/10.1038/s41598-020-74478-y

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Journal: Scientific Reports	Publication Date: Oct 20, 2020
Citations: 27	License type: open-access

Affiliation: University of North Texas

Abstract

Ecological, health and environmental concerns are driving the need for bio-resourced foams for the building industry. In this paper, we examine foams made from polylactic acid (PLA) and micro cellulose fibrils (MCF). To ensure no volatile organic compounds in the foam, supercritical CO2 (sc-CO2) physical foaming of melt mixed systems was conducted. Mechanical and thermal conductivity properties were determined and applied to a net zero energy model house. The results showed that MCF had a concentration dependent impact on the foams. First structurally, the presence of MCF led to an initial increase followed by a decrease of open porosity, higher bulk density, lower expansion ratios and cell size. Differential Scanning Calorimetry and Scanning Electron Microscopy revealed that MCF decreased the glass transition of PLA allowing for a decrease in cell wall thickness when MCF was added. The mechanical performance initially increased with MCF and then decreased. This trend was mimicked by thermal insulation which initially improved. Biodegradation tests showed that the presence of cellulose in PLA improved the compostability of the foams. A maximum comparative mineralization of 95% was obtained for the PLA foam with 3 wt.% MCF when expressed as a fractional percentage of the pure cellulose reference. Energy simulations run on a model house showed that relative to an insulation of polyurethane, the bio-resourced foams led to no more than a 12% increase in heating and cooling. The energy efficiency of the foams was best at low MCF fractions.

Highlights

Ecological, health and environmental concerns are driving the need for bio-resourced foams for the building industry
polylactic acid (PLA) foams reinforced with micro cellulose fibrils in three different weight percent concentrations (1.5, 2.25 and 3 wt.%) were developed using the solid-state batch foaming process with CO2 as the blowing agent
The micro cellulose fibrils acted as nucleating agents and created numerous nucleation sites by lowering the G value required for bubble nucleation

Summary

Introduction

Ecological, health and environmental concerns are driving the need for bio-resourced foams for the building industry. Using the extrusion foaming process with C O2 and N 2 gas as a blowing agent, the mechanical properties of plain PLA foams were compared with those reinforced with joncryl chain extender. To improve the mechanical properties of both solid and foam composites made from PLA, it has been blended with a range of natural fibers such as jute, kenaf, wood flour/fiber, cellulose crystals and whiskers[15,16,17,18,19,20]. The results obtained showed that the mechanical properties of the reinforced PLA composites were comparable to those of conventional polypropylene based thermoplastic composites with a maximum flexural modulus value of 8.9 GPa recorded at 30 wt.% fiber reinforcement. Cellulose microfibrils (MCF) have been produced using different techniques such as; micro fluidization, grinding, high-intensity ultra-sonication

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Conclusion