Average Fiber Length Research Articles

Effects of initial fiber length and fiber length distribution on the properties of carbon-fiber-reinforced-polypropylene composites

In this study, short carbon fiber-reinforced polypropylene composites with three different initial carbon fiber lengths were prepared by using extrusion compounding and injection molding techniques. The physical and morphological properties of the prepared short carbon fiber-reinforced composites were investigated by means of tensile test, differential scanning calorimetry and scanning electron microscopy. Final fiber length distributions of composites were also determined by using an image analyzing program. It was found that the maximum number of fibers was observed in the range from 51 to 100 µm. Number average final fiber lengths were calculated between 230 and 280 µm. Regardless of the used initial carbon fiber length, tensile strength and modulus values of the composites increased with the increasing carbon fiber content. It has been concluded that the initial fiber length at the studied range did not have any significant effect on the properties of composites.

Development of a bovine collagen–apatitic calcium phosphate cement for potential fracture treatment through vertebroplasty

The aim of this study was to examine the potential of incorporating bovine fibres as a means of reinforcing a typically brittle apatite calcium phosphate cement for vertebroplasty. Type I collagen derived from bovine Achilles tendon was ground cryogenically to produce an average fibre length of 0.96±0.55mm and manually mixed into the powder phase of an apatite-based cement at 1, 3 or 5wt.%. Fibre addition of up to 5wt.% had a significant effect (P⩽0.001) on the fracture toughness, which was increased by 172%. Adding ⩽1wt.% bovine collagen fibres did not compromise the compressive properties significantly, however, a decrease of 39–53% was demonstrated at ⩾3wt.% fibre loading. Adding bovine collagen to the calcium phosphate cement reduced the initial and final setting times to satisfy the clinical requirements stated for vertebroplasty. The cement viscosity increased in a linear manner (R2=0.975) with increased loading of collagen fibres, such that the injectability was found to be reduced by 83% at 5wt.% collagen loading. This study suggests for the first time the potential application of a collagen-reinforced calcium phosphate cement as a viable option in the treatment of vertebral fractures, however, issues surrounding efficacious cement delivery need to be addressed.

A Determining Method of Paper Fiber Density and Equivalent Diameter

It is very important to measure paper fiber density and equivalent diameter for pulp suspension as solid-liquid two-phase flow in fluid dynamics study. There are some kinds of ways to measure fiber density，but not be suit for pulp fiber density because of their limitations. By using kajaaniFS300 fiber analyzer provided by Mesto ltd company to compare and measure all kinds of fiber length, fiber coarseness, weight average fiber length can more accurately show the actual length of fiber. The results shows that it is apparently more appropriate to calculate fiber density by using fiber coarseness, weight-average fiber length and weight-average fiber width, and fiber equivalent diameter should also be calculated according to the same weight-average fiber length and weight-average fiber width.

Bite Force Estimation and the Fiber Architecture of Felid Masticatory Muscles

Increasingly, analyses of craniodental dietary adaptations take into account mechanical properties of foods. However, masticatory muscle fiber architecture has been described for relatively few lineages, even though an understanding of the scaling of this anatomy can yield important information about adaptations for stretch and strength in the masticatory system. Data on the mandibular adductors of 28 specimens from nine species of felids representing nearly the entire body size range of the family allow us to evaluate the influence of body size and diet on the masticatory apparatus within this lineage. Masticatory muscle masses scale isometrically, tending toward positive allometry, with body mass and jaw length. This allometry becomes significant when the independent variable is a geometric mean of cranial variables. For all three body size proxies, the physiological cross-sectional area and predicted bite forces scale with significant positive allometry. Average fiber lengths (FL) tend toward negative allometry though with wide confidence intervals resulting from substantial scatter. We believe that these FL residuals are affected by dietary signals within the sample; though the mechanical properties of felid diets are relatively similar across species, the most durophagous species in our sample (the jaguar) appears to have relatively higher force production capabilities. The more notable dietary trend in our sample is the relationship between FL and relative prey size: felid species that predominantly consume relatively small prey have short masticatory muscle fibers, and species that regularly consume relatively large prey have relatively long fibers. This suggests an adaptive signal related to gape.

Biocomposites reinforced with cellulose nanocrystals derived from potato peel waste

This study investigated the effectiveness of cellulose nanocrystals derived from potato peel waste as a reinforcement and vapor barrier additive. The nanocrystals were derived from cellulosic material in the potato peel by alkali treatment and subsequently acid hydrolysis. TEM images revealed the average fiber length of the nanocrystals was 410nm with an aspect ratio of 41; its aspect ratio being considerably larger than cotton-derived nanocrystals prepared using similar reaction conditions. Cellulose nanocrystals (CNC)-filled polyvinyl alcohol (PVA) and thermoplastic starch (TPS) films were prepared by solution casting method to maintain uniform dispersion of the 1–2% (w/w) filler content. An increase of 19% and 33% (starch composite) and 38% and 49% (PVA composite) in tensile modulus was observed for the 1% and 2% CNC-reinforced composites, respectively. Water vapor transmission measurements showed a marginal reduction of water permeability for the PVA composite, whereas no effect was observed for the thermoplastic starch composite.

Fiber and Yarn Performance of Upland Cotton with Improved Fiber Bundle Strength

ABSTRACTThe U.S. cotton (Gossypium spp.) industry has shifted focus in recent years to an export market, necessitating further development of upland cotton (G. hirsutum L.) cultivars with superior fiber properties to maintain competitiveness. This study was conducted to compare both fiber and yarn performance of upland cotton genotypes with similar average fiber length but enhanced fiber bundle strength (Str) with two high quality commercial controls, ‘FM 832LL’ and ‘DP 491’. The high Str strains and commercial upland controls were grown in Weslaco, TX, during the summers of 2009 and 2010 with standard agronomic practices for south Texas, including furrow irrigation. Plots were spindle‐machine harvested, seedcotton ginned on a research gin without a lint cleaner, and lint and yarn tested at the Fiber and Biopolymer Research Institute (FBRI) in Lubbock, TX. Lint and yarn data collected included high volume instrument (HVI) and advanced fiber information system (AFIS) derived data and ring spun yarn data (mini‐spinning protocol). Years were different for almost every fiber and yarn property except Str, immature fiber content (IFC), yarn tenacity (Ten), work required for yarn breakage (Work to Break) and the number of thin places per kilometer that are at least 50% smaller in diameter than adjacent portions of yarn (Thin). All of the high Str strains had higher Ten in 2009 than the controls and 9 of the 11 had higher Ten in 2010. The high Str genotypes resulted in more even yarns (as determined with the Uster Tester 3 [Uster Technologies]).

Study on short glass fiber‐reinforced poly(3‐hydroxybutyrate‐co‐4‐hydroxybutyrate) composites

AbstractBiobased non‐fossil polyester poly(3‐hydroxybutyrate‐co‐4‐hydroxybutyrate) (P3/4HB) containing 4.0 mol % 4‐hydroxybutyrate (4HB) was melt‐mixed with short glass fibers (SGF) via a co‐rotating twin‐screw extruder. The compositing conditions, average glass fiber length and distribution, thermal, crystallization, and mechanical properties of the P3/4HB/SGF composites were investigated. Calcium stearate, two kinds of paraffin wax and modified ethylene bis‐stearamide (TAF) were investigated as lubricants for the P3/4HB/SGF composites. It revealed that TAF is the most efficient lubricant of the P3/4HB/SGF composites. Coupling agents 2,2′‐(1,3‐phenylene)bis‐2‐oxazoline (1,3‐PBO) and pyromellitic dianhydride (PMDA) were used as end‐group crosslinkers to reduce the degradation of P3/4HB and increase the mechanical properties of the P3/4HB/SGF composites. It showed that 1,3‐PBO is the efficient coupling agent. The optimum condition of the P3/4HB/SGF composites is 1.5 phr TAF, 1.0 phr 1,3‐PBO, and 30 wt % glass fiber content. And the maximum of tensile strength, tensile modulus, and impact strength of the composites is 3.7, 6.6, 1.8 times of the neat P3/4HB polymer, respectively. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

Sample size considerations in human muscle architecture studies

This report is a meta-analysis of the human muscle architecture literature that analyzes the number of muscles, number of subjects, and muscle fiber length coefficient of variation (CV) by body region. Muscle fiber length data are used to make recommendations for dissection-based architectural study sample sizes. An average of 9 ± 10 (mean ± SD) muscles and an average of 9 ± 5 subjects were reported in the 26 studies considered. Across all studies, average fiber length CV was highly variable (18% ± 5%). This shows that sample sizes required to achieve adequate power varies by anatomical region. Studies involving muscle architecture should consider regional variability and effect size and determine sample size accordingly.

Controllable synthesis and tunable field-emission properties of tungsten oxide sub-micro fibers

A large amount of tungsten oxide (W18O49) sub-micro fiber arrays was prepared via a novel method on tungsten substrates, using tungsten trioxide powders as the source. Different growth densities and diameters of W18O49 sub-micro fibers were obtained when synthesized temperature was changed from 800°C to 950°C. The morphology and structure of the tungsten oxide sub-micro fibers were characterized by SEM, X-ray diffraction, and TEM. The average length of the resultant tungsten oxide sub-micro fibers is more than 5μm, and their diameters are about several hundred nanometers. The synthesized fibers have a single-crystalline monoclinic structure with the growth direction of [010] and their growth mechanisms are discussed. Also, the relationships between the sub-micro fibers' field emission properties and their diameters and growth densities are investigated.

Effect of dynamical converging channels on fiber organization and damage during vane extrusion of sisal fiber‐reinforced polypropylene composites

AbstractIt is well known that converging channel can generate elongational deformation field. In this study, novel dynamical converging channels were successfully incorporated into plant fiber‐reinforced thermoplastics composites processing. A dynamical elongational deformation field (DEDF) generated by these channels was studied. The fiber organization and damage in the DEDF has been investigated in terms of its relationship to changes in rotating speed of the channels. A vane extruder based on these channels was used to prepare sisal fiber‐reinforced polypropylene composites. By investigating rapidly cooled samples in the vane extruder, sisal fiber in the center part of these channels has an orientation with an angle to the discharging direction. Rotating speed increases from 30 to 90 r/min result in 30.99–42.7% decreases in average fiber length. The issues of fiber distribution and voids formation have been related to the mechanical properties of the composites, particularly tensile strength and modulus. Increased rotating speeds from 30 to 90 r/min results in tensile strength and modulus increases of about 21.3% and 11.6%, respectively. The majority of this change is caused by decreased voids formation with the increases of speed, which is in agreement with scanning electron microscopy of the composites. POLYM. COMPOS., 2012. © 2011 Society of Plastics Engineers

The effect of span length of flexural testing on properties of short fiber reinforced composite

The aim of this study was to determine the effect of different span lengths of flexural testing on some properties of test specimens made of experimental short fiber reinforced composite resin (FC). Bar shaped specimens with different lengths were made from experimental FC composite with an average fiber length of 3 mm and particulate filler composite (PFC, control: Z250). The specimens (n = 8) were polymerized with a hand light-curing unit for 40 s and dry stored in a room temperature for 24 h before testing. Three-point flexural test for determination of ultimate flexural strength, toughness and flexural modulus of specimens was made with different span lengths (20, 15, 10, 7, 6, 5 mm) with a speed of 1.0 mm/min until fracture. By shortening the span length for specimens made of FC or PFC, the flexural modulus decreased (from ca. 11 to 4 GPa) and flexural toughness increased (from ca. 0.25 to 2.25 MPa). Reduction in flexural strength by shortening the span length was found with PFC (from 170 to 125 MPa) but not with FC, which showed reduction by span lengths from 20 to 7 mm and considerable increase of flexural strength by further shortening the span length from 7 to 5 mm. Shortening of span length of flexural testing showed linear reduction of the measured and calculated flexural properties of PFC and some properties of FC, but flexural strength values for FC were non-linearly related to the span length: the highest values were obtained with the longest and the shortest span lengths. In reporting the flexural values of composites, the span length-specimen dimension ratio, and the length of the reinforcement need to be taken into consideration.

Detecting abnormalities of corpus callosum connectivity in autism using magnetic resonance imaging and diffusion tensor tractography

The corpus callosum (CC) has emerged as one of the primary targets of autism research. To detect aberrant CC interhemispheric connectivity in autism, we performed T1-weighted magnetic resonance imaging (MRI) and diffusion tensor imaging (DTI)-based tractography in 18 children with high functioning autism (HFA) and 16 well-matched typically developing (TD) children. We compared global and regional T1 measures (CC volume, and CC density), and the DTI measures [fractional anisotropy (FA), apparent diffusion coefficient (ADC), average fiber length (AFL), and fiber number (FN)] of transcallosal fibers, between the two groups. We also evaluated the relationships between scores on the Childhood Autism Rating Scale (CARS) and CC T1 or DTI measurements. Significantly less white matter density in the anterior third of the CC, and higher ADC and lower FN values of the anterior third transcallosal fiber tracts were found in HFA patients compared to TD children. These results suggested that the anterior third CC density and transcallosal fiber connectivity were affected in HFA children.

The moisture and temperature effect on mechanical performance of flax/starch composites in quasi‐static tension

AbstractThe effect of temperature and moisture on mechanical behavior of flax fiber/starch based composites was investigated experimentally. Elastic modulus, the nonlinear tensile loading curves, and failure strain were analyzed. Neat matrix and composites with 20 and 40% weight content of fibers were tested. It was found, performing tests with different amplitudes, that microdamage development with stress is rather limited and the related elastic modulus reduction in this type of composites is not significant. It was shown that the composite elastic modulus and failure stress are linearly related to the maximum tensile stress in resin. The sensitivity of the maximum stress of the resin with respect to temperature and moisture is the source of composites sensitivity to these parameters. Constant interface stress shear lag model for stress transfer assuming matrix yielding at the fiber/matrix interface has been successfully used to explain the tensile test data. It indicates that the sensitivity of the used composite with respect to the matrix properties change could be significantly reduced by increasing the average fiber length from 0.9 mm to 1.5 mm. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers

Correlation between processing conditions and fiber breakage during compounding of glass fiber‐reinforced polyamide

AbstractThe inter‐relationship between processing conditions and fiber breakage has been studied for glass fiber‐reinforcedpolyamide 12, prepared using (i) an internal batch mixer, (ii) a laboratory scale corotating twin screw extruder, and (iii) an industrial scale twin screw extruder. The average fiber lengths and fiber length distributions were measured for various compounding conditions (screw or rotor speed, mixing time, feed rate). Experimental results have shown that fiber breakage depends on both screw speed and mixing time, the later being controlled, in an extruder, by the feed rate. For a given compounding system (batch mixer or twin screw extruder), the energy input (specific mechanical energy, SME) during the compounding process is found to be a reliable parameter, which governs fiber length (average, minimal, and maximal) evolution. Experimental data are correctly described with a model defining change in fiber length as a function of SME. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers

Effects of Enzymatic Modification of Masson Pine Mechanical Pulp on Fiber Morphology and Pulp Properties

Mechanical pulping is a kind of high yield pulping that comes with the comprehensive utilization of plant material. Mechanical pulp has lots of benefits, such as simple process, low pollution, good bulkiness, fine stiffness, excellent optical performance and good printability. However, it also has disadvantages of lower paper physical strength and higher refining energy. In this paper, AU-MTPE90 enzyme and acid xylanase were used to modify the masson pine mechanical pulp before refining. The effects of modification on the shape parameters of masson pine mechanical pulp fiber and pulp properties were studied. The results showed that after modified by AU-MTPE90 enzyme and acid xylanase，the drainability of the refined pulp increased, the average fiber length increased and the fines percent decreased. The curl index and kink index increased slightly after modified by AU-MTPE90 enzyme，while the kink index decreased after modified by xylanase.

Properties of wood chips for thermomechanical pulp (TMP) production as a function of spout angle

Abstract Spruce wood chips were produced under well-controlled conditions in a laboratory wood chipper at spout angles of 30°, 40°, and 50° at a cutting rate of 20 m s-1 and with a nominal chip length of 25 mm. The chips were then refined under thermomechanical pulp (TMP) conditions in a pilot refiner plant. The pulp properties such as freeness, average fiber length, and shives content were determined and evaluated as a function of specific energy consumption. For a first stage refining and for a freeness value of 350 ml, a decrease in specific electrical energy consumption could be achieved by performing the wood chipping at a spout angle of 50° as compared to 30° which is the spout angle commonly used. A patent application regarding this method has been filed and is pending. It is realized that a freeness value is not directly indicative of any quality measure, such as, for example tensile index and light scattering coefficient but the obtained results can be interpreted to be promising. Further studies are needed regarding the impact of the modified chipping process.

Polypropylene/natural fibres composites: Analysis of fibre dimensions after compounding and observations of fibre rupture by rheo-optics

Fibre size distribution and the way how fibres are breaking during compounding with polypropylene were analysed. Two types of cellulose-based fibres were used: natural flax and man-made (regenerated) cellulose, Tencel. No significant influence of Tencel initial fibre size on its final size after processing was observed. However, the fibre type and the presence of defects have a stronger effect on the rupture. The value of the average final length of flax fibres was found to be similar to the distance between kink bands. In order to understand fibre rupture mechanisms, they were observed using a rheo-optical system which enabled visualization of fibre break-up. All fibres studied broke by fatigue after an accumulation of strain, contrarily to what is known for glass fibres. Flax fibres broke around the kink bands while Tencel® broke after numerous bending.

Application of NSSC pulping to sugarcane bagasse

The NSSC pulping process was investigated to produce pulp from bagasse for corrugating board manufacture. The chemical contents including cellulose, lignin, ash, and extractives soluble in alcohol-acetone measured 55.75, 20.5, 1.85, and 3.25, respectively. The average fiber length, fiber diameter, lumen width, and cell wall thickness of bagasse were 1.59 mm, 20.96, 9.72, and 5.64 μm, respectively. The optimum conditions, with a yield of 74.95%, were achieved using 20 percent chemicals on the basis of sodium oxide, cooking temperature of 170 °C, and cooking time of 30 minutes. Pulp was refined to freeness 345 and 433 mL CSF according to Canadian standards. 127 g m-2 handsheets from both pulps were made and strength properties measured. Statistical analysis of results indicated that paper derived from freeness 345 and 433 mL CSF had better strength properties in all indices in comparison with NSSC pulp from hardwoods produced at Mazandaran Pulp and Paper factory, Iran.

Effects of Cellulase Modification on Fiber Surface and Quality of Masson Pine Mechanical Pulp

At present, paper industry has a lot of problems in China, such as the shortage of forest resources and high cost of pulping. Paper industry must be seeking high yield and low cost pulping process. In order to reduce the cost of mechanical pulp and increase the use of mechanical pulp, a lot of research and patent showed that the refining energy consumption of mechanical pulp would be further decreased using the corresponding enzyme to modify fiber of the raw materials before refining. The effects of cellulases modification on masson pine mechanical pulp were investigated in this paper. The modification conditions were as follows: the dosage of enzyme 75IU/g (to bone dry materials), temperature 500C, time 150min, pH value 5.5 and pulp concentration 15%. The effects of cellulase modification on the surface and quality of masson pine fiber of mechanical pulp were investigated by scanning electron microscope (SEM), atomic force microscopy (AFM) and fiber quality analyzer (FQA). It was found from the images of SEM that the original fiber surface was smoothly but markedly corroded after the cellulase modification. Moreover, the modification brought about more external fibrillation and longitudinal tearing during refining. AFM measurement results showed that the fiber surface roughness was improved after the cellulase modification because that the middle lamella, primary wall and outer layer of secondary wall were broken. The results of FQA measurement showed that the average fiber length increased slightly.

The Effect of Microwave Treatment on the Hydrogen Peroxide Bleaching of Soda-AQ Wheat Straw Pulp

In this paper, the effect of microwave treatment on the hydrogen peroxide bleaching of Soda-AQ wheat-straw pulp was investigated. The results showed that microwave treatment could increase the brightness of the hydrogen peroxide bleached pulp. The fiber coarseness of microwave enhancing peroxide bleached pulp was higher than that of the peroxide bleached pulp. However, the arithmetic average fiber length, the length weighted average fiber length and weight weighted average fiber length of the former was lower than that of the latter. Fourier transform infra-red spectroscopy (FTIR) and X-ray diffraction (XRD) spectra showed that CrI(%) crystallinity of microwave enhancing peroxide bleached pulp was similar as that of the peroxide bleached pulp but all higher than that of the Soda-AQ wheat-straw pulp. N·O′KI infra-red crystalline index of microwave enhancing peroxide bleached pulp were lower than that of the peroxide bleached pulp. The FTIR spectra of lignin showed that the microwave treatment had some influences on the methoxyl and phenolic group in lignin.