Changes In Fiber Properties Research Articles

Simultaneous modification and solidification of bamboo Fiber/Epoxy composites

Bamboo fiber (BF) composite is a sustainable and environmentally friendly material. However, the traditional preparation process requires multiple modification processes, leading to changes in fiber properties, and often results in strength loss and energy waste. To address these issues, we report a novel tetrahydromethyl-1,3-isobenzofurandione epoxy system (MeTHPA-EP) that can simultaneously modify BF and solidify the matrix, resulting in a more efficient and sustainable composite material. In the BF/MeTHPA-EP forming process, BF acts as an “accelerator,” promoting the curing reaction and advancing the exothermic peak of the matrix by 10℃. Meanwhile, MeTHPA acts as a “bridge,” reducing the wettability of BF by 35–50% and decreasing the porosity to 1.02%. The combined effect of these two factors significantly strengthens BF as reinforcement, increasing matrix strength by 5.77 times and modulus by 5.82 times, exhibiting apparent ductile bulk failure. Furthermore, we conducted a comparison with the traditional isophorone diamine curing agent, verifying the superiority of the MeTHPA-EP system in reducing voids and enhancing interfacial stability. Our research expands the applicability of bamboo fiber as a reinforcing material, providing a cost-effective, environmentally friendly, and effective method for producing high-performance bamboo fiber composites.

Influence of Different Hot Runner-Systems in the Injection Molding Process on the Structural and Mechanical Properties of Regenerated Cellulose Fiber Reinforced Polypropylene.

The increasing demand for renewable raw materials and lightweight composites leads to an increasing request for natural fiber composites (NFC) in series production. In order to be able to use NFC competitively, they must also be processable with hot runner systems in injection molding series production. For this reason, the influences of two hot runner systems on the structural and mechanical properties of Polypropylene with 20 wt.% regenerated cellulose fibers (RCF) were investigated. Therefore, the material was processed into test specimens using two different hot runner systems (open and valve gate) and six different process settings. The tensile tests carried out showed very good strength for both hot runner systems, which were max. 20% below the reference specimen processed with a cold runner and, however, significantly influenced by the different parameter settings. Fiber length measurements with the dynamic image analysis showed approx. 20% lower median values of GF and 5% lower of RCF through the processing with both hot runner systems compared to the reference, although the influence of the parameter settings was small. The X-ray microtomography performed on the open hot runner samples showed the influences of the parameter settings on the fiber orientation. In summary, it was shown that RCF composites can be processed with different hot runner systems in a wide process window. Nevertheless, the specimens of the setting with the lowest applied thermal load showed the best mechanical properties for both hot runner systems. It was furthermore shown that the resulting mechanical properties of the composites are not only due to one structural property (fiber length, orientation, or thermally induced changes in fiber properties) but are based on a combination of several material- and process-related properties.

Impact of wet-drying Treatment of Raffia and Okra Fibres on Their Morphological, Physicochemical and Mechanical Properties

ABSTRACT Hornification is an irreversible effect that occurs on lignocellulosic fibers when they are subjected to drying and re-wetting cycles. This study aimed to evaluate okra and raffia fibers morphological, physico-chemical, and mechanical properties. The fibers were subjected to four and six wet-dry treatment cycles to assess the effect of the number of cycles on the performance of each fiber. The results show that four wet-dry cycles show an increase in density from 1.40 g/cm3 to 1.78 g/cm3 and from 1.34 g/cm3 to 1.58 g/cm3 for okra and raffia fibers, respectively. Furthermore, a decrease in fiber lumen is observed, resulting in a reduction in water absorption capacity of up to 18.3% for raffia fiber and 56.3% for okra after four hornification cycles. Statistical analysis reveals a significant improvement in the elastic modulus of raffia fiber up to 37% after treatment, while no significant improvement is observed in the elastic modulus and tensile strength of okra fiber. This is attributed to the strengthening of intracellulosic bonds, which resulted in the creation of more available -OH sites on the fibers. The physico-chemical and mechanical changes in fiber properties resulting from wet-dry processing have demonstrated their suitability to replace synthetic fibers in composites.

Effect of Fiber Chemical Treatments on Rice Straw Fiber Reinforced Composite Properties

ABSTRACT This work reports the effect of alkali, enzyme, and their sequential combination treatment on rice straw fiber properties (fiber diameter, aspect ratio, fiber length, bundle strength and elongation). The change in fiber properties and its association with rice straw fibers reinforced epoxy biocomposites has been studied. Biocomposites, prepared using the hand lay-up technique, were characterized using FTIR, TGA and SEM. The mechanical properties viz. tensile, flexural, impact and compression were measured according to the ASTM standards. Sound transmission loss and noise reduction coefficient of the composites was also determined. Results showed that the alkali and enzyme treatment to the rice straw significantly reduced fiber length and fiber diameter by 50%. Enzyme treatment caused the highest reduction in fiber diameter which increased the aspect ratio. The sequential combination of alkali and enzyme yielded significant improvements in the tensile (20%), flexural (22%), impact (98%), and compression (328%) strength of the composites. The noise reduction coefficient (0.95) of all rice straw composites was found excellent. Thus, alkali-enzyme pretreated rice straw fiber composite product is a good choice for agro-residue valorization and industrial product development.

Analysis of changes in fiber properties in processes opening, cleaning and carding

This article investigated and examined the change in the quality properties of cotton fiber and degree of purification. In the technological process of blowing, cleaning and carding. The basic purpose of this study determine the optimizing the technological parameters of blowing, cleaning and carding process for normal yarns by using fiber which is estimated as the average quality by the USTER®. Short fiber cotton was used to produce normal counts, i.e Ne 30 OE yarn spun on Autoconer 9 spinning frame. Yarn produced by spinning process from semifinished products collected at different type technological parameters of spinning process shows variable yarn properties. The study of all these parameters plays important role to achieve better quality output of the spinning process.

Development of alkali-treated surface-modified coir fibre filter for 1µm to 10 µm particle filtration and process optimization

Filtration of Particulate Matter (PM) 2.5 and PM 10 particles are focused by the filters used in Heating, Ventilation and Air Conditioning (HVAC) systems. Synthetic fibres/filaments are widely used to construct the filters for air conditioning filters and cleanroom filters which is not biodegradable. Natural fibres are easily biodegradable, exhibit better filtration characteristics as like synthetic fibres. In this research, alkali-treated coir fibres are used to construct the filter for filtering the particle range of 1.0 µm to 10 µm. Box- Behnken experimental design was used for the experimental plan and the experiments were conducted to construct the filters. The change in fibre properties by alkali-treatment was observed and the treatment with 5% and 10% alkali increases the crystallinity index of fibres. The influence of independent variables on the performance of developed filters was analyzed in detail. 5% NaOH treated fibre sample with 20% resin proportion and 60 g fibre content in the unit area was identified by a quality factor as the best combination of independent variables for constructing filter.

Development of fibre properties in mill scale high- and low consistency refining of thermomechanical pulp (Part 1)

Abstract The aim of this study was to evaluate changes in fibre properties with high (HC)- and low consistency (LC) refining of TMP and determine how these contribute to tensile index. Two process configurations, one with only HC refining and another with HC refining followed by LC refining were evaluated in three TMP mainline processes in two mills using Norway spruce. An increase in tensile index for a given applied specific energy was similar for all LC refiners in the three lines, despite differences in the fibre property profiles of the feed pulps. Compared with only HC refined pulps at a given tensile index, HC+LC refined pulps had greater fibre wall thickness, similar fibre length, strain at break and freeness, but lower light scattering coefficient, fibre curl and external fibrillation. The degree of internal fibrillation, determined by Simons’ stain measurements, was similar for both configurations at a given tensile index. The results indicate that the increase in tensile index in LC refining is largely influenced by a decrease in fibre curl and in HC refining by peeling of the fibre walls. Compared at a given tensile index, the shive content (Somerville mass fraction) was similar for both HC+LC and HC refining.

Does High Voltage Electrical Discharge Treatment Induce Changes in Tannin and Fiber Properties of Cocoa Shell?

Cocoa shell is a by-product of the chocolate industry that is rich in dietary fiber and bioactive components. In this research, the influence of high voltage electric discharge (HVED) treatment on chemical and physical characteristics of the cocoa shell, i.e., the effects of applied time and frequencies on grinding ability, water binding capacity (WBC), dietary fibers and tannin content was investigated. HVED had a significant influence on the chemical and physical properties of cocoa shell, all of which could be linked to changes in fiber properties. Along with the fiber content, grinding ability and water binding capacity were increased. These properties have already been linked to fiber content and soluble/insoluble fiber ratio. However, this research implies that change in fiber properties could be linked to tannin formation via complexation of other polyphenolic components. Additional research is needed to verify this effect and to establish mechanisms of tannin formation induced by HVED and its influence on fiber quantification.

Effects of alkalization on the properties of Ensete ventricosum plant fibre

Ensete ventricosum (EV) fibre is a lignocellulosic plant fibre hitherto, to the best of our knowledge, unexplored in terms of its response to alkali treatment at room temperature. The chemical compositions as well as physical and tensile properties of this fibre were evaluated after alkali treatment (in 2–15%w/v NaOH at 23 ± 2 °C for 1 h). Effects of alkali concentration on fibre properties were analysed and compared with that of untreated fibres. EV fibres treated with alkali solutions between 2 and 10% (w/v NaOH) exhibited all round improvement in physical, morphological, tensile, structural and thermal properties as compared to that of untreated EV fibres. Unlike the cellulose content, hemicellulose content of alkalized fibres decreased substantially with increase in alkali concentration. The 10% NaOH treated fibres showed the highest improvement in tenacity (9.1 gf/den), crystallinity index (71%) and other properties. Changes in fibre properties were further confirmed by SEM, XRD and TGA.

The Improvement of Mechanical Properties, Thermal Stability, and Water Absorption Resistance of an Eco-Friendly PLA/Kenaf Biocomposite Using Acetylation

As a result of industrialization and environmental pollution, increasing importance is being given to eco-friendly materials and technology. In particular, eco-friendly biocomposites using polylactic acid (PLA) have attracted great interest. In this work, fiber-reinforced composites were investigated in order to enhance the mechanical properties and improve the economic efficiency of PLA. Specifically, composite materials using natural fibers, such as kenaf were actively studied. In the utilization of natural fibers, such as kenaf, the treatment method for increasing the bonding force between the fiber and the matrix is very important. In this study, the surface of kenaf was treated using an acetylation technique, and the PLA composite material was prepared using surface-treated kenaf. Changes in fiber properties were observed with acetylation treatment time. The mechanical properties, thermal stability, and water absorption resistance of the acetylated kenaf and PLA composites prepared for each condition were evaluated. Finally, was concluded that acetylation treatment is effective for improving the performance of PLA/kenaf composites. This behavior was found to relate to the surface cleaning of acetylated kanaf, in addition to the efficient modification of the hydrophilic characteristics of kenaf.

Plant Fibre: Molecular Structure and Biomechanical Properties, of a Complex Living Material, Influencing Its Deconstruction towards a Biobased Composite.

Plant cell walls form an organic complex composite material that fulfils various functions. The hierarchical structure of this material is generated from the integration of its elementary components. This review provides an overview of wood as a composite material followed by its deconstruction into fibres that can then be incorporated into biobased composites. Firstly, the fibres are defined, and their various origins are discussed. Then, the organisation of cell walls and their components are described. The emphasis is on the molecular interactions of the cellulose microfibrils, lignin and hemicelluloses in planta. Hemicelluloses of diverse species and cell walls are described. Details of their organisation in the primary cell wall are provided, as understanding of the role of hemicellulose has recently evolved and is likely to affect our perception and future study of their secondary cell wall homologs. The importance of the presence of water on wood mechanical properties is also discussed. These sections provide the basis for understanding the molecular arrangements and interactions of the components and how they influence changes in fibre properties once isolated. A range of pulping processes can be used to individualise wood fibres, but these can cause damage to the fibres. Therefore, issues relating to fibre production are discussed along with the dispersion of wood fibres during extrusion. The final section explores various ways to improve fibres obtained from wood.

Effect of alkali and silane surface treatments on regenerated cellulose fibre type (Lyocell) intended for composites

Cellulose fibres have significant importance and potential for polymer reinforcement. It is essential to modify the surface of the fibre to obtain good fibre-matrix interface. Surface treatments can increase surface roughness of the fibre, change its chemical composition and introduce new moieties that can effectively interlock with the matrix, resulting in good mechanical properties in the composites. This is mainly due to improved fibre-matrix adhesion. The treatments may also reduce the water absorption rate by converting part of the hydroxyl groups on the fibre surface into other functional groups. Chemical modification of the surface of a regenerated cellulose fibre of the Lyocell type was carried out by alkali and silane treatments, which significantly changed the properties of the Lyocell fibres. Three parameters were considered when the fibre surface treatment was done: concentration (2–15 wt%), temperature (25 and 50 °C) and time (30 min–72 h). Fourier transform infrared spectroscopy and Raman spectroscopy were used for chemical analysis and qualitative analysis of the cellulose crystallinity due to the surface treatments; subsequently, mechanical strength of the fibres was tested by tensile testing. Weight loss, moisture regain and swelling measurements were taken before and after treatments, which showed the obvious changes in fibre properties on treatment. Heat capacity of the fibres was measured for untreated and treated fibres, and thermal degradation of fibres was examined to see the stability of fibres at elevated temperatures. Wettability and surface energies were measured using dynamic contact angle method in three wetting mediums. Scanning electron microscopy was used to study the morphological properties of the fibres.

Electrospinning cellulose acetate nanofibers and a study of their possible use in high-efficiency filtration

Cellulose acetate was dissolved in trifluoroacetic acid and electrospun onto polypropylene non-woven material. An upstream layer of polypropylene non-woven material was added to form a three-layered polypropylene/cellulose acetate/polypropylene filter. The thickness of the electrospun cellulose acetate layer was varied by changing the electrospinning time. The fabricated filter was then characterized. Cellulose acetate nanofibers were also electrospun onto an aluminum foil collector with the aim of studying the changes in fiber properties when they are electrospun onto the polypropylene non-woven material. The results obtained in this research work indicated that the layer of nanofibers electrospun onto polypropylene non-woven material increased the filtration efficiency of polypropylene non-woven material from 50.23% to 91.29%, but the quality factor reduced by 29.1%. When the cellulose acetate deposition time was increased from 3 h to 6 h, the filtration efficiency further increased to 98.26% and the quality factor increased by 0.6%. A comparison between cellulose acetate nanofibers electrospun using an aluminum foil as the collector and those electrospun directly onto the polypropylene non-woven material indicated that cellulose acetate fibers electrospun onto polypropylene non-woven material had poorer fiber quality properties.

A comparison of fibre deformations from mill like and laboratory kraft cooking of softwood

Abstract The fact that industrial pulps have a lower strength than their corresponding laboratory pulps is an unsolved problem affecting in various ways the potential fibre utilisation in different mills. The loss of pulp strength has to a great extent been attributed to changes at the fibre level. In order to clarify in what way changes in fibre properties contribute to the strength losses, cooking experiments were conducted using a laboratory batch digester in which mechanical forces may be introduced. Fibre properties, i.e. fibre structure and fibre strength, of laboratory-made pulps were compared with those of an industrial pulp. It was concluded that two essentially different mechanisms may be identified; one related to the transverse fibre shape, the other to fibre damage. The latter is manifested as lower rewetted zero-span strength which reduces tear resistance and tensile strength of the pulp. The former is a collapse of the fibre, reducing the lumen area and resulting in a pulp with lower water-retaining capacity, given sheets of lower density and a pulp that has to be beaten to a higher degree to reach the desired bonding and the desired tensile strength.

Displacement washing of TEMPO-oxidized softwood kraft pulp: Effects of change in fiber properties

Article Displacement washing of TEMPO-oxidized softwood kraft pulp: Effects of change in fiber properties was published on August 1, 2013 in the journal Nordic Pulp & Paper Research Journal (volume 28, issue 3).

Effects of Pressure during Preform Densification on SiC/SiC Composites

The nano-infiltration and transient eutectic-phase (NITE) method is one of the most attractive methods for fabrication of SiC and SiC/SiC composites. In the NITE method, preform densification is essential option for damage less near-net shaping technique. However, optimization of preform densification is insufficient yet. The objective of this study is to evaluate the effects of pressure during preform densification on SiC/SiC composites. The preform before preform densification has many pores in the inter-prepreg sheets. These pores were disappeared by preform densification. As the effects of pressure on preform, densification in the intra-fiber-bundle was improved due to increasing pressure. Flexural strength of the preforms with 1 MPa and 17 MPa indicated almost same value. The result suggested that increasing of pressure did not cause any change in fiber properties. In the effects of pressure on the composites, the composites with 17 MPa was exhibited improvement in bulk density and mechanical property, compared with that with 1 MPa.

Photoaggravation of hair aging.

Photoaggravation of hair aging includes various chemical and physical changes in fiber properties which lead to an increase in fiber porosity, loss of mechanical strength and an increase in surface roughness. These changes come from lipid oxidation, disulfide bond cleavage, tryptophan degradation and cysteic acid formation. Hair exposed to sunlight is claimed to be more brittle, stiffer and drier than before irradiation and exhibits a reduced water-absorption capacity. Hair pigments function to provide photochemical protection to hair proteins. Hair pigments accomplish this protection by absorbing and filtering the impinging radiation and subsequently dissipating this energy as heat. However, in the process of protecting the hair proteins from light, the pigments are degraded or bleached. Dark hair is more resistant to photodegradation than light hair, because of the higher photostability of eumelanin compared to pheomelanin. Integral lipids of hair fibers are degraded by ultraviolet light, as well as by visible light, helping to explain the weakening of the cell membrane complex exposed to light radiation.

Effect of sodium hydroxide pre-treatment on the optical and structural properties of lyocell

Lyocell is a type of regenerated cellulose. Fibres spun from cellulose solution in N-methylmorpholine- N-oxide hydrate consist of crystalline cellulose II and amorphous cellulose. Lyocell fabrics were treated with aqueous sodium hydroxide solution (NaOH) to study the influence of alkali on optical and structural properties. It was observed that sodium hydroxide treatment causes the density, orientation and crystallinity of lyocell fibre to decrease with increasing sodium hydroxide concentration, a corresponding decrease in tensile strength is also observed. The greatest change in fibre properties occurs between 3.0 and 5.0 mol dm −3 NaOH. This is attributed to the onset of formation of Na–cellulose II at 3.0 mol dm −3 NaOH; a fully formed Na–cellulose II structure is expected above 6.8 mol dm −3 NaOH. Formation of Na–cellulose II causes plasticization of the lyocell fibres as both inter- and intra-molecular hydrogen bonds are broken by these higher sodium hydroxide concentrations.

Pilling in cellulosic fabrics, Part 2: A study on kinetics of pilling in alkali‐treated lyocell fabrics

AbstractAs pilling in textiles originates from many factors, the kinetic of pilling formation play an important role in the investigation and approaches of pilling. The single jersey‐knitted lyocell fabrics were treated with different alkaline solution concentrations and submitted to Rapid Pilling Test—a wet‐state Martindale test for cellulosic fabrics performed with increasing abrasion cycles. After each type of cycles, the pilling density was microscopically counted, and then pilling was visually rated. The changes in fiber properties were followed by water retention values (WRV), fibers swelling, fiber wet abrasion resistance (NSF), and fibers tenacity/elongation in wet and in dry states. The kinetics of pill formation—quantified by pills/cm2—occurred in the following steps: pills are promptly formed at first abrasion cycles, reached the pill plateau cycles, and are self‐removed from the fabric surface. The untreated and alkali‐treated lyocell fabrics followed a similar trend of pill formation. However, the pilling propensity is distinct depending on the concentrations. The changes in the swollen state of fiber properties and fiber–fiber friction mainly determined the pill kinetics in lyocell fabrics. The kinetic model aims to figure out the pilling mechanism and the appropriate treatment for pilling resistance. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008

Change in fiber properties due to the heat treatment of nylon 6 tire cords

AbstractNylon 6 is used as a reinforcing material in different rubber products. However, as it is a thermoplastic material, it may undergo some kind of thermal shrinkage during the vulcanization of rubber, which leads to dimensional stability problems in the rubber product. To prevent this, we subjected nylon 6 to some kind of thermal treatment at higher temperatures. During thermal treatment, there was some change in the mechanical properties, shrinkage which may have been correlated with changes in the crystal structure of the polymer. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci 2008