Cellulose – Polycarbonate Nanocomposites: A novel automotive window alternative

Abstract

Nanocrystalline cellulose (NCC) has great potential as a reinforcing agent in thermoplastics (such as polyesters, polyamides and polycarbonates) due to its high mechanical strength and aspect ratio – being compared with reinforcements like steel and carbon nanotubes. In order to maintain its strength when compounded with thermoplastics, the high-temperature processing must not damage the structural integrity of the nanocrystalline cellulose. The processing temperature for polyesters, polyamides and polycarbonates is relatively high and near to the onset of thermal degradation of cellulose bio products, therefore care must be taken to ensure the preservation of the structural integrity of nanocrystalline cellulose.

The thermal stability and the kinetics of thermal degradation of five different cellulose samples were studied using an Ozawa-Flynn-Wall method and thermogravimetric analysis data. To complete the characterization of the NCC for polymer processing applications, the crystallinity index was determined using X-ray diffraction; surface morphology was studied with scanning electron microscope, chemical composition was studied using FT-IR, and moisture content was measured using a moisture analyser. Each of these properties observed is essential to the end mechanical properties of the polymer nanocomposite as these properties will affect the dispersion and interfacial adhesion of the fibres to the polymer matrix.

After a complete investigation of the cellulose reinforcements, a procedure was developed for dispersion of the NCC fibres into a polycarbonate matrix followed by the moulding of specimen bars. The mechanical properties of the five cellulose-polycarbonate nanocomposites – for example, tensile modulus, flexural modulus and impact strength – were tested and compared to the homo-polycarbonate. The motivation for this project was to design a new material for use as strong, lightweight window substitute; an alternative to conventional residential/commercial windows and a lightweight alternative to conventional automotive glass, offering increased fuel efficiency.