The methodology of multi-scale structural assessment of the different cellulose fibre cement boards subjected to high temperature treatment was proposed. Two specimens were investigated: Board A ...(air-dry reference specimen) and Board B (exposed to a temperature of 230 °C for 3 h). At macroscale all considered samples were subjected to the three-point bending test. Next, two methodologically different microscopic techniques were used to identify evolution (caused by temperature treatment) of geometrical and mechanical morphology of boards. For that purpose, SEM imaging with EDS analysis and nanoindentation tests were utilized. High temperature was found to have a degrading effect on the fibres contained in the boards. Most of the fibres in the board were burnt-out, or melted into the matrix, leaving cavities and grooves which were visible in all of the tested boards. Nanoindentation tests revealed significant changes of mechanical properties caused by high temperature treatment: "global" decrease of the stiffness (characterized by nanoindentation modulus) and "local" decrease of hardness. The results observed at microscale are in a very good agreement with macroscale behaviour of considered composite. It was shown that it is not sufficient to determine the degree of degradation of fibre-cement boards solely on the basis of bending strength; advanced, microscale laboratory techniques can reveal intrinsic structural changes.
•Cellulose fibres can cause hydration inhibition, especially µm-scale fibre.•TGA-based chemically bound water in cellulose fibres needs to be calibrated.•Mm-scale cellulose fibre has a significant ...effect on enhancing tensile behaviour.•Fibre length plays a fundamental effect on the tensile properties of cement composites.
In this work, one type of commonly used commercial cellulose fibre with lengths ranging from μm to mm is introduced into cement paste at concentrations of 0.1 wt% to 10 wt% to study its effect on enhancing tensile behaviour and microstructural evolution at the early curing stage. Significantly inhibited hydration due to cellulose fibre incorporation is revealed, and the degree of inhibition increases as the length of the cellulose fibres decreases. Additionally, the degree of hydration calculated by the TGA data of cellulose fibre-incorporated cement paste needs to be calibrated against the mass loss of cellulose fibres during heating because it cannot be directly deduced by the TGA data of pure cellulose fibres. Only mm-scale cellulose fibres significantly improve the post-peak ductility, whereas µm-scale cellulose fibres have a weak enhancement effect on the post-peak ductility. It is found that cellulose fibres at both the μm and mm scales can enhance the tensile strength at day 28. Regarding this type of commercial cellulose fibre, it is optimal to adopt the mm-scale cellulose fibres because of their significant effect on improving tensile behaviour.
The thermal degradation behaviour of hemp (
Cannabis sativa L.) fibres under a nitrogen atmosphere was investigated by using thermogravimetry (TGA). The kinetic activation energy of treated fibres ...was calculated from TGA data by using a varied heating rate from 2.5 to 30
°C/min. The greater activation energy of treated hemp fibre compared with untreated fibre represented an increase of purity and improvement in structural order. A hydrophobic solvent affected the degree of non-cellulosic removal. Mercerisation and enzyme scouring removed non-cellulosic components from the fibre; however, structural disruption was observed after higher alkaline concentration, 20
%wt/v and longer scouring time, respectively. Structural disruption was observed by X-ray measurement. The FTIR results indicated an elimination of the non-cellulosic components by the mercerisation treatment and a specific removal of low methoxy pectin by use of pectate lyase enzyme (EC 4.2.2.2). An increase of temperature at the maximum rate of degradation and the rate of weight loss was characteristic of the purity and structure of treated hemp fibre.
•Paper sludge (PS) mainly consists of cellulose and calcite.•Cellulose fibre (CF) reduce the shrinkage of clay bricks.•CF and CaCO3 decomposition products change the microstructure of the clay ...body.•The optimal amount of PS additive in a clay brick is up to 15%.
The paper analyses the effect of waste sludge from paper industry (paper sludge) on physical and mechanical properties of clay bricks, their microstructure and resistance to freezing and thawing. Paper sludge is not hazardous industrial waste mainly consisting of cellulose and calcite. Clay bodies were made from the mix containing from 5% to 20% of paper sludge and fired at 900 °C and 1000 °C temperatures. Open pore structure in the clay body is developed as a result of burnt cellulose fibres and calcite decarbonization. Physical and mechanical properties of clay bodies change depending on the content of added PS: shrinkage, density and compressive strength reduce, water absorption and effective porosity increase. It is recommended to add 5% of paper sludge to the clay body and fire it at 900 °C temperature, or alternatively add 5–15% of paper sludge and fire the clay body at 1000 °C temperature. In terms of resistance to freezing and thawing, such products are regarded as frost resistant in moderately aggressive environment, i.e. in structures protected from direct environmental effects.
Fibres and textiles from synthetic polymers offer high functionality with regard to sweat transport and drying rate in sports clothing. However, the limited biodegradability of standard polyester and ...polyamide fibres leads to concerns with regard to release of micro-plastics and disposal. Here, a hydrophobic coating is used on cellulose fibre and subsequent blending with untreated fibre to bring about a modified yarn with optimised water transport properties.
The hydrophobic surface of the hybrid fibres is designed to resemble synthetic fibres like polyester or polyamide. In dynamic tests 90% of water was transferred from hydrophobic cellulose fabric into a hydrophilic cellulose layer, less than 10% of the added volume was held back in the capillaries of the hybrid material. The core of the fibres however exhibits the characteristics of cellulosic fibres thus dyeing of the hybrid fibres with standard reactive dyes for cellulose is possible. Water sorption of the hybrid fibres and water retention of the surface modified cellulose fibre were determined with 8 %wt and 30–35 %wt respectively. Thus both parameters remained at the typical level of unmodified cellulose fibres.
This work is an example of an alternative method to replace synthetic fibres with bio derived and biodegradable material in functional clothes.
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•Coating of cellulose fibres leads to biodegradable alternatives for synthetics.•Hydrophobic coatings of cellulose fibres retards water uptake.•Bulk properties of cellulose fibres were not affected by surface coating.•Surface coating increases water transport properties and retards swelling.•Surface modification permits wider application for the biomaterial cellulose.
Thermal stability, chemical structure and microstructure of cellulose fibre under cement paste and dry conditions at different temperature were tested to investigate its temperature adaptability in ...cement-based composites. Results demonstrated that after curing for 60 days at 60 and 90 °C, the compressive strength of cement paste containing 0.4 wt% cellulose fibre increased 16.16% and 22.79%, respectively. However, the compressive strength of the paste curing at 120 and 150 °C had no enhancement effect. Compared with the dry condition, cement paste filtrate had a significant influence on chemical structure and microstructure at 120 and 150 °C. In filtrate cured at 120 °C, β-1,4-polyglucose in cellulose fibre underwent alkaline hydrolysis, fragmenting cellulose fibre to smaller pieces, which converted the “fibrous structure” to “cluster structure”. However, in filtrate cured at 150 °C, reducing end group in cellulose fibre underwent peeling reaction, which decreased its thermal stability and changed its crystallinity from 0.69 to 0, whereby microstructure transformed into “agglomeration structure”.
•Effects of high temperature on the mechanical properties of the cement paste reinforced by cellulose fiber was investigated.•Microstructure of cellulose fiber in cement paste at high temperature was evaluated.•Chemical structure and microstructure of cellulose fiber cured dry and cement slurry filtrate were studied.
Assessment of viral contamination is essential for monitoring the microbial quality of water and protection of public health, as human virus presence is not accurately determined using bacterial ...indicators. Currently, the time required for conventional viral testing means that water contaminated with human pathogens may be used (e.g. for drinking, recreation or irrigation) days before results are available. Here we report a new rapid method for coliphage enumeration, the QuantiPhage (QP) assay. The novelty of the assay is the use of cellulose absorbent pad materials to support coliphage growth and colorimetric detection, in place of agar that is used in the plaque assay. In addition to saving time associated with agar preparation and tempering, the QP assay enabled enumeration of somatic coliphages in 1.5–2 h and F+ coliphages in 2.5–3 h. The assays were highly sensitive, with a lower detection limit of 1 plaque forming unit (PFU) per mL where 1 mL sample volumes were analysed, and 1 PFU per 10 mL where 10 mL sample volumes were analysed. This is the first rapid culture assay to enable low numbers of coliphages to be reliably detected and to produce directly equivalent results to agar-based plaque assays. A novel gelatin-immobilisation method is also reported, that reduces time to prepare bacterial cells from ∼20 h to 40–60 min (depending on the assay format), and provides a ready to use form of cells, that is compatible with rapid detection and kit formats. When applied to analysis of somatic coliphages in wastewater samples and surface water samples, mean differences in results of the QP assay and the conventional plaque assay were not statistically significant (mean difference ≤ 0.15 log10 PFU/L and 0.5 PFU/10 mL respectively, P > 0.05). The QP is a valuable tool for assessing microbial water quality, which may assist in improving the management of water resources.
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•Rapid, sensitive (1 PFU/10 mL) and simple culture method for enumerating coliphages.•Somatic coliphages can be detected in 1.5 h (>100 PFU) to 2 h (1–100 PFU).•F+ coliphages can be detected in 2.5 h (>100 PFU) to 3 h (1–100 PFU).•Use with freshly cultured or immobilised (ready to use) host bacteria.•Equivalent results to the conventional plaque assay, but in a much faster time.
This work examines size effects of ductile regenerated cellulose fibres (viscose) with different diameters (11.9, 16.6 and 48.4 μm) as well as their unidirectional epoxy composites reinforced with ...fibre mass fractions of 20, 30 and 40% (16, 25 and 34% in volume). Viscose fibres were tested at different clamping lengths ranging between 2 and 50 mm. Composites were produced in 2 different sizes (cross-sectional area of 6.3 and 41.2 mm
2
) and tested at different gauge lengths (35 and 100 mm). It was investigated to what extent size effects affect the tensile strength and if the two-parameter least squares Weibull statistics may be used for the prediction of strength values when the sample volume of fibres or composites is changed. The results have shown that the Weibull theory is in principle applicable. It has been found that the prediction accuracy is only sufficient if the Weibull strength is determined on the basis of Weibull parameters determined at small sample volumes for the prediction of data measured with higher specific sample volumes. In this case, all calculated data are within the mean arithmetic deviation of the experimental results. If, on the other hand, the prediction is based on parameters determined for larger sample volumes, a considerable overestimation of the strength data of samples having a smaller sample volume is the result.
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