Cellulose nanofibers produced from banana peel by chemical and mechanical treatments: characterization and cytotoxicity assessment

Cellulose nanoparticles from a vegetable source (cellulose fiber) have been evaluated for future use as reinforcement of polymeric matrixes (e.g., biodegradable films). Cellulose nanoparticles have numerous advantages: they are inexpensive and biodegradable, and they originate from renewable sources. Here, cellulose nanofibers (CNFs) were isolated from banana peel by chemical (alkaline treatment and bleaching followed by acid hydrolysis with 0.1, 1, or 10% (v/v) H2SO4) and mechanical (high pressure homogenizer) treatments. Atomic Force Microscopy (AFM) analysis showed all treatments effectively isolated banana fibers at the nanometer scale (average diameter of 3.72 nm). CNFs displayed -potential values ranging from -37.60 to -67.37 mV, which prevented their aggregation. CNFs had high crystallinity values, from 63.1 to 66.4%, which indicated they could be good reinforcing agents. FTIR results confirmed that the chemical and mechanical treatments removed the amorphous fractions. Regarding cytotoxicity, low CNF concentrations (50-500 g/mL) did not cause cell death, but CNFs at concentrations above 1000 g/mL significantly decreased cell viability. The use of different sulfuric acid concentrations provided more detailed knowledge of the treatment methods and CNF features, which could help to improve the CNF production process. The combination of chemical and mechanical treatments proved to be an efficient strategy to prepare CNFs from banana peels as a potential reinforcing agent of polymeric matrixes (e.g., food packaging).The authors would like to acknowledge the financial support provided by Coordenaçao de Aperfeiçoamento de Pessoal de Nível ~ Superior (2952/2011), Conselho Nacional de Desenvolvimento Científico e Tecnologico (150523/2013-0 and 140274/2014-6), and CAPES/FCT 349/13 for the PhD exchange program. Joana T. Martins acknowledges the Foundation for Science and Technology for her fellowship (SFRH/BPD/89992/2012). This study was supported by FCT under the scope of the strategic funding of UID/BIO/04469/ 2013 unit and COMPETE 2020 (POCI-01-0145-FEDER-006684) and BioTecNorte operation (NORTE-01-0145-FEDER-000004) funded by the European Regional Development Fund under the scope of Norte2020 - Programa Operacional Regional do Norte. This study was also supported by FCT under the scope of the Project RECI/BBBEBI/0179/2012 (FCOMP-01-0124-FEDER-027462). The authors would also like to acknowledge the Brazilian Nanotechnology National Laboratory (LNNano) for allocation of the TEM and AFM apparatus.info:eu-repo/semantics/publishedVersio

Materials produced from plant biomass: part II: evaluation of crystallinity and degradation kinetics of cellulose

In this study Eucalyptus grandis (CEG) and Pinus taeda (CPT) cellulose fibers obtained from kraft and sulfite pulping process, respectively, were characterized using Fourier transform infrared (FTIR) spectroscopy and thermogravimetry (TGA). The degradation kinetic parameters were determined by TGA using Coats and Redfern method. FTIR results showed that CPT presented a more ordered structure with higher crystallinity than CEG. Thermogravimetric results showed that CPT had a higher thermal stability than CEG. The kinetic results revel that for CEG the degradation mechanism occurs mainly by random nucleation, although phase boundary controlled reactions also occurs while for CPT the degradation process is more related with phase boundary controlled reactions. Results demonstrated that differences between thermal stability and degradation mechanisms might be associated with differences in the cellulose crystalline structure probably caused by different pulping processes used for obtaining the cellulose fibers

Utilization of Areca Nut Leaf Sheath Fibers for the Extraction of Cellulose Whiskers

In this study, cellulose whiskers were extracted from an agricultural plant waste, Areca Nut Leaf Sheath, by employing a sulfuric acid hydrolysis method. The effect of hydrolysis time and temperature on the morphology, crystallinity, and degree of polymerization of the resultant cellulose particles was studied. Highly crystalline cellulose whiskers with an aspect ratio around 20 were obtained under moderate conditions of hydrolysis by maintaining the temperature at 45°C and hydrolysis time of 180 min. However, on increasing the temperature and time of hydrolysis, surface flattening of fibers was observed and aspect ratio was decreased. Isolated cellulose whiskers were found to contain traces of biosilica

Utilization of Areca Nut Leaf Sheath Fibers for the Extraction of Cellulose Whiskers

In this study, cellulose whiskers were extracted from an agricultural plant waste, Areca Nut Leaf Sheath, by employing a sulfuric acid hydrolysis method. The effect of hydrolysis time and temperature on the morphology, crystallinity, and degree of polymerization of the resultant cellulose particles was studied. Highly crystalline cellulose whiskers with an aspect ratio around 20 were obtained under moderate conditions of hydrolysis by maintaining the temperature at 45°C and hydrolysis time of 180 min. However, on increasing the temperature and time of hydrolysis, surface flattening of fibers was observed and aspect ratio was decreased. Isolated cellulose whiskers were found to contain traces of biosilica.</p

Reutilization of polyurethane-based shoe sole scrap as a reinforcing filler in natural rubber for the development of high-performance composites

Reutilization of industrial waste is one of the emerging strategies to combat solid waste disposal for the protection of our environment. The present work describes a novel and economic approach to reutilize finely ground shoe sole scrap, a thermoset polyurethane-based waste (PUW) material generated during shoe sole production in footwear industries as an efficient reinforcing filler in natural rubber (NR). Shoe sole scrap was ground to fine powder and characterized by various analytical techniques. NR-PUW composites were prepared using 0–20 phr (parts per hundred of rubber) of PUW. The cure characteristics, mechanical, thermal, and morphological properties of prepared composites were studied. Composite with 5 phr PUW showed a remarkable improvement in tensile strength by 10% and modulus at 300% elongation increased by 9% compared to that of neat sample. A considerable increase in abrasion resistance and tear strength was also observed in 5 phr PUW loaded composites. Other mechanical properties like hardness, heat build-up and compression set showed a regular increase with further filler loading. To estimate the level of interfacial adhesion between the filler and the matrix, the experimental values of tensile strength were compared with Nicolais–Narkis (N–N), Lu, and Turcsányi–Pukànszky–Tüdõs (T–P–T) models and elastic modulus values with Einstein and Guth and Smallwood models. The tensile strength values are in agreement with T-P-T model (B = 4), up to 5 phr PUW proving the better adhesion between NR and PUW at lower filler loadings. At higher PUW loading, the experimental results are approaching Lu and N–N models indicating that this adhesion is collapsed. The incorporation of PUW as a filler in NR does not adversely impact the thermal stability of prepared composites. The results obtained are not only promising from a circular economy perspective, but also is contributive in production of high-performance, low-cost NR composites for various industrial applications. </jats:p