Abstract
Poly(vinyl alcohol) foams, containing different amounts of microfibrillated cellulose, were prepared through an eco-friendly procedure based on high-speed mixing and freeze-drying. The effect of filler amount on cell shape and regularity was studied by scanning electron microscopy (SEM) and the evolution of the microstructure was assessed through dynamic cryo-SEM. Fourier Transformed Infrared Analysis and Differential Scanning Calorimetry measurements revealed the presence of hydrogen bond interaction among cellulosic filler and the matrix. The modulus and compression deflection of neat PVA were significantly improved by increasing the amount of microfibrillated cellulose content with respect to foams realised with pulp cellulose fibers.
Highlights
Polymer foams, due to their unique structure and properties, are widely used in all those applications for which light-weight, thermal/acoustic barrier effects and shock-impact absorption are required, ranging from the automotive sector to packaging systems, from construction to technical footwear [1]
Poly(vinyl alcohol) (PVA)-MFC5: (a) Sample frozen in liquid nitrogen and observed
scanning electron microscopy (SEM) image in Figure 3g (PVA-MFC30), where it is shown that the cellulose fibres with large for foam containing 40 wt % of WPC, and this is attributed to the high fibre content, which hinders a regular cell expansion during foaming
Summary
Due to their unique structure and properties, are widely used in all those applications for which light-weight, thermal/acoustic barrier effects and shock-impact absorption are required, ranging from the automotive sector to packaging systems, from construction to technical footwear [1]. Petroleum-based polymer foams possess serious environmental problems after end-use, due to their non-biodegradability and difficult disposal. Pulp cellulose fibres are widely used as filler in polymer composites [9,10]. High MFC content (up to 40 wt %) PVA foams were prepared and characterised with the aim of understanding and clarifying the effect of the addition of a high amount of filler on the properties and morphologies of the PVA foams. The mechanism of formation of the double porosity was clarified and the effect of MFC on the properties of the foams was analysed through physico-mechanical characterisations in comparison to PVA foams containing pulp cellulose fibres
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