The effect of the dispersion of microfibrillated cellulose on the mechanical properties of melt-compounded polypropylene–polyethylene copolymer

Abstract

Microfibrillated cellulose (MFC) is a highly expanded, high surface area networked form of cellulose-based reinforcement. Due to the poor compatibility of cellulose with most common apolar thermoplastic matrices, the production of cellulosereinforced composites in industry is currently limited to polar materials. In this study, a facile water-based chemistry, based on the reaction of MFC with tannic acid and subsequent functionalisation with an alkyl amine, is used to render the surface of the MFC fibrils hydrophobic and enhance the dispersion of the cellulose-based filler into an apolar thermoplastic matrix. The level of dispersion of the compatibilized MFC reinforced composites was evaluated using Time of Flight Secondary Ion Mass Spectrometry and multi-channel Spectral Confocal Laser Scanning Microscopy. The agglomeration of cellulosic filler within the composites was reduced by functionalising the surface of the MFC fibrils with tannic acid and octadecylamine. The resulting composites exhibited an increase in modulus at a high cellulose content. Despite the dispersion of a large portion of the functionalised filler, the presence of some remaining aggregates affected the impact properties of the composites produced.

Employing photoluminescence to rapidly follow aggregation and dispersion of cellulose nanofibrils

“…2 Their high specific Young's modulus, calculated to be around 85 N m g -1 for CNCs and 65 N m g -1 for CNFs; 3 sustainable sources; ease of functionalization and biocompatibility have resulted in their use for an array of potential applications. 1,2 These vary from composites and packaging, [4][5][6][7][8][9] to drug delivery, 10,11 tissue engineering 12 and food additives 13 with final forms including films, textile fibres, and gels.…”

“…2,25,26 The autofluorescence of poly-and oligo-saccharides, from various sources, has previously been widely reported. 6,[27][28][29][30][31][32][33][34][35] This autofluorescence is generally attributed to contamination of the sample with aromatic compounds, i.e. lignin, or proteins, dependent on the source.…”

“…We previously took advantage of this phenomenon to track the dispersion of cellulose particles in polymer matrices, confirming that the observed autofluorescence was intrinsically linked to the presence of cellulose. 6,31 In relation to cellulosic nanomaterials with typical surface chemical modifications, Li et al investigated the autofluorescent properties of carboxymethylated nanocellulose. 33 They demonstrated that the particles exhibited two fluorescent bands with an approximate wavelength difference of 40 nm, the second of which increased with concentration.…”

Microfibrillated Cellulose Suspension and Its Electrorheology

“…New sources, new mechanical processes, and new pre-and post-treatments are being continuously developed to reduce the high energy consumption used to fabricate a new type of MFC particles for engineering applications [12]. From this point of view, MFC has great potential to be used as a bio-based structural-reinforcing cost-efficient material [13]. Therefore, a good understanding of the rheological and other properties of the MFC is required.…”

Recent Developments in Cellulose Nanomaterial Composites

“…Palange et al chemically modified CMF using a water‐based, facile method to first attach tannic acid (TA) to the surface and then an alkyl amine, hexylamine, to create a less hydrophilic nanoparticle surface. [ 99 ] The nanoparticles were melt‐mixed with PP–PE copolymers using a twin‐screw extrusion system; up to 20 wt% modified MFC was added. Despite chemical modification, materials showed evidence of agglomerates, with a typical aggregate length of ≈100 µm.…”