Residual Fiber Research Articles

Blending cottonseed meal products with different protein contents for cost-effective wood adhesive performances

Water washed cottonseed meal (WCSM) is an excellent bio-adhesive resource because of its cost-effective extraction process and environmentally friendly performance. To evaluate the effects of protein content on the adhesive performance of cottonseed meal-based adhesives, we reconstituted cottonseed meal products with protein contents ranged from 34.9% to 94.8% by blending different amounts of WCSM, cottonseed protein isolate (CSPI), and residues after protein extraction (CSIR). Their physicochemical properties and three types of adhesive strengths (dry, wet, and soaked) were measured with press temperatures at 100, 150 and 170 °C. The morphological and rheological data showed that the low-protein-content adhesives with a high amount of residual cotton hull and fiber possessed poor spreadability and adhesive strength. Molecular and thermal analysis suggested that protein ratio had a stronger influence than press temperature to thermal property and adhesive strength. With these data, multiple linear regression models were established, providing analytical tools to predict the bonding strength affected by protein content and press temperature in cottonseed meal-based adhesives. On the other hand, the blends with 65–70% of protein content demonstrated the bonding performance and flowability comparable to highest protein product CSPI (94.8% protein) within the acceptable standard deviations. Thus, these observations and data could be helpful in set-up of industrial standard requirements and quality control for protein content in cost-effective adhesive-grade WCSM products.

Delay Effect on Coherent Transfer of Optical Frequency Based on a Triple-Pass Scheme**Supported by the National Natural Science Foundation of China under Grant No 61378037, and the Fundamental Research Funds for the Central Universities under Grant No JUSRP51628B.

We demonstrate a triple-pass scheme for coherent transfer of optical frequency and the delay effect on the fiber phase noise compensation. It is theoretically proved that the delay effect consists of both fiber delay and servo delay. The delay effect confines the servo bandwidth within 1/8τ and induces a residual fiber phase noise after noise compensation. For a 25-km-long fiber, the servo bandwidth is found to be around 1 kHz, and the fiber phase noise is suppressed approaching to the theoretical limitation. The triple-pass scheme enables the simultaneous transfer of optical frequency to multiple remote users. The performance of noise compensator in the triple-pass scheme can achieve a similar level result compared with that in the double-pass scheme.

Effects of growth stage and growing degree day accumulations on triticale forages: 2. In vitro disappearance of neutral detergent fiber

The use of winter triticale (X Triticosecale Wittmack) in dairy-cropping systems has expanded greatly in recent years, partly because of its value as a forage crop but also to improve land stewardship by providing winter ground cover. Our objectives were to use 2-pool and 3-pool nonlinear models to characterize in vitro disappearance of neutral detergent fiber (NDF) and then describe the relationship between estimated parameters from those models with plant growth stage or growing degree days (GDD) >5°C for winter triticale forages harvested during 2016 and 2017 in Marshfield, Wisconsin. Forages were harvested from replicated field plots each year at growth stages ranging from stem elongation to soft dough. All NDF analyses included use of sodium sulfite and heat-stable α-amylase with residual fiber corrected for contaminant ash (asNDFom). Nonlinear 3-pool models for in vitro disappearance of asNDFom that included fast (Bfast) and slow (Bslow) disappearance pools as well as an associated disappearance rate for each (Kdfast and Kdslow, respectively) were easily fitted provided that a single discrete lag time was applied to both Bfast and Bslow pools to reduce the number of parameters to be estimated. An unresolved issue related to fitting 3-pool decay models was the incomplete recovery of asNDFom from immature triticale forages at 0 h, which was partially resolved with 2 approaches that produced similar estimates of Kdfast and Kdslow. Most parameters obtained from 2- and 3-pool decay models for asNDFom could be related to growth stage or GDD using polynomial regression techniques, often with high coefficients of determination (R2). For 3-pool models of asNDFom disappearance, Bslow increased with plant maturity, but the associated Kdslow ranged narrowly from 0.011 to 0.015/h and could not be related to growth stage or GDD by quartic, cubic, quadratic, or linear regression models. Despite different cultivars coupled with substantial differences in precipitation across years, single endpoint estimates of in vitro disappearance of asNDFom after 24, 30, or 48 h of incubation were closely related (R2 ≥ 0.906) to growth stage and GDD by linear or quadratic regression models that were generally similar across production years. Typical recommendations for harvesting triticale at boot stage to facilitate the planting of a double crop are strongly supported by the extensive 30-h in vitro disappearance of asNDFom at that growth stage, which was 63.1 and 64.8% of asNDFom during 2016 and 2017, respectively.

Application of Melt-Blown Poly(lactic acid) Fibres in Self-Reinforced Composites.

The aim of our research was to produce poly(lactic acid) (PLA) fibres with diameters in the micrometer size range, serving as the reinforcing phase in self-reinforced (SR) PLA composites. Nonwoven PLA mats were manufactured by solvent-free melt-blowing technology. Three types of PLA differing in d-lactide content were processed with a productivity as high as 36 g/h. The crystallinity of the PLA microfibres was enhanced by thermal annealing. A 2–3-fold increase in the degree of crystallinity was obtained, as measured by differential scanning calorimetry (DSC). Fibre diameters between 2–14 µm were revealed by scanning electron microscopy (SEM). Static tensile tests were performed on the nonwoven mats, showing the reduced moduli of the annealed fibres due the amorphous relaxation. The PLA mats were processed via the hot compaction technique and formed into SR–PLA composites. The morphological and mechanical properties of the obtained microstructural composites were comprehensively studied. Composites prepared from annealed, thermally more stable PLA nonwoven mats showed superior mechanical properties; the tensile strength improved by 47% due to the higher residual fibre content.

Automatic glass fiber length measurement for discontinuous fiber-reinforced composites

Severe fiber breakage occurs in injection molding, affecting the mechanical performance of discontinuous fiber-reinforced composites. Accurate measurement of the residual fiber length distribution is crucial to experimentally investigate the physics of fiber breakage. This work proposes an automatic glass fiber length measurement method, based on the algorithm CT-FIRE for individual fiber detection. The main parameters of the algorithm were optimized to minimize the average systematic error between measurements performed with CT-FIRE and with a high-accuracy CMM. An approach to the evaluation of the measurement uncertainty based on substitution measurements was proposed and verified for a large size sample. For the scanner used in this study the uncertainty was 0.651 mm.Eventually, the developed automatic measurement method was used to investigate fiber breakage during plastication of long glass fiber-reinforced PP. The results obtained using the optimized algorithm parameters showed that significant breakage is due to the presence of the dynamic mixer.

Indium Tin Oxide Coated Two-Mode Fiber for Enhanced SPR Sensor in Near-Infrared Region

A surface plasmon resonance (SPR) sensor based on side-polished two-mode fiber (TMF) coated with indium tin oxide (ITO) film is proposed. ITO enables tuning of resonance wavelength of the sensor through changing its carrier concentration. The advantages of the TMF and ITO are combined in the sensor, which can achieve high sensitivity and plasma frequencies in the near-infrared region. The impact of ITO film thickness and residual fiber thickness on the sensing performance are numerically investigated with LP01 and LP11a modes coupled to specific surface plasmon modes. The results show that the resonance wavelength locates in 1500–2200 nm and an average sensitivity of ∼10149 and ∼10400 nm/RIU can be achieved for LP01 and LP11a modes, respectively, when the environmental refractive index varies between 1.33 and 1.39. The penetration depths of evanescent wave for the LP01 and LP11a modes are 460 and 502 nm, respectively. Both the sensitivity and penetration depth of the sensor are larger than those of single-mode fiber and multimode fiber based SPR sensors. The proposed sensor can play an important role in various applications, including environment, medicine, and security.

Optimal fiber distribution for tensile properties of injection molded composite

The survival rate of a composite is the residual fiber length divided by the initial fiber length, and it decreases with the initial fiber length and fiber volume content (Vf) during injection molding processes. The degree of damage is higher for carbon fiber than for glass fiber, and the survival rate increases with a hyperbolic tangent relationship as the nozzle diameter increases. Higher survival rate corresponds to a stronger material. Five different lengths of fiber with 29 different size fibers were selected based on the distribution and shape of residual fiber in experimental works. These were examined to study the effects of fiber distribution on the tensile properties of a short-fiber reinforced composite (SFRC). Compared with the experimental results, the modulus predicted using the Halpin-Tsai relation shows reasonable agreement with the prediction obtained using the residual fiber length instead of the initial fiber length. It was found that the tensile modulus and strength generally differ by a factor of up to 3.2, depending on the fiber distribution patterns with Vf = 30%, and the trend is more significant as the fiber aspect ratio increases. The interactions between the fiber and matrix and the staggered-type distribution are the most important factors in the reinforcement of the SFRC. With the same combination of short fiber length, an optimized fiber distribution pattern is suggested.

Fiber breakage behavior of long glass fiber-reinforced polypropylene through the convergent channel

Fiber breakage occurs during the processing of fiber-reinforced thermoplastics, thereby resulting in the deterioration of the mechanical properties of the thermoplastic parts. In this paper, the fiber breakage and flow behavior of long glass fiber-reinforced polypropylene containing 30 wt% glass fibers was investigated through a series of conical capillary die at varying shear rates, conical die angles or diameters, and the melt flow index of polypropylene. Moreover, scanning electron microscopy was employed to observe individual fiber cross sections to analyze the mechanism of fiber breakage, of which the conical capillary die geometry dominantly affected the residual fiber length, and the choice of an appropriate geometry most significantly affected improvements in the residual fiber length. The results also indicated an increase in the extent of fiber breakage following an increase in the shear rates. In addition, long glass fiber-reinforced polypropylene also generated a slightly higher average fiber length following an increase in the melt-flow index of polypropylene. Pressure oscillations were observed at the entrance, of which these pressure accumulations and releases affected fiber interactions and breakage at the entrance.

Influence of foaming technology on fibre breakage in long fibre-reinforced polypropylene composites parts

ABSTRACTIt is generally believed that the residual fibre length is one of the most important factors influencing on the mechanical properties of fibre-reinforced polymer matrix composites. In this study, long-glass fibre-reinforced polypropylene (LGFRPP) with initial fibre lengths of 12 mm was prepared and then moulded into parts via conventional injection moulding (CIM) and foamed injection moulding (FIM). The design of experiment (DOE) based on the Taguchi method was first used to determine the optimised processing conditions to increase the residual fibre length of the LGFRPP. The results indicated that foaming conditions have a substantial influence on the residual fibre length of the foamed samples. Based on the DOE, a set of optimised processing condition was selected, and two representative samples of CIM and FIM were carefully investigated using dynamical mechanical analysis, scanning electron microscopy, optical microscopy, etc. The experimental results further showed that the residual fibre length and the mechanical properties of the LGFRPP FIM components were better than those of the CIM components. It was also determined that there is a close relationship between the fibre breakage and the mechanical performance.

Mechanical properties, fiber orientation, and length distribution of glass fiber‐reinforced polypropylene parts: Influence of water‐foaming technology

It is generally believed that the length, length distribution, and orientation of fibers are important influencing factors on the mechanical properties of fiber‐reinforced polymer matrix composites. In this study, the length, length distribution, and orientation of fibers with respect to the loading direction of glass fiber‐reinforced polypropylene (GF‐PP) parts were investigated. GF‐PP of different initial fiber lengths, 2 mm (SGF‐PP) and longer than 2 mm (LGF‐PP), were prepared and then molded into parts via conventional injection molding (CIM) and water‐foamed injection molding (WFIM). The mechanical performance of samples was determined using tensile and impact tests, the residual fiber length and length distribution were measured, and the fiber orientation was observed by optical camera and scanning electron microscopy (SEM). The experimental results showed that the mechanical properties of LGF‐PP WFIM components were better than those of the CIM components, while the SGF‐PP parts were worse than the solid ones. The results also suggested that the LGF‐PP WFIM samples exhibited the best fiber length and length distribution, and a lesser degree of fiber orientation, along the flow direction, compared with the CIM samples. It was also shown that the fibers in the GF‐PP foamed parts that were longer than a critical length, which possibly exceeded that of the solid parts, were more effective in improving the mechanical properties. Thus, it can be concluded that the property enhancements of the LGF‐PP parts can be attributed to the effect of cell growth based on an interpretative model of the interaction of long fibers and foamed cells. POLYM. COMPOS., 39:4386–4399, 2018. © 2017 Society of Plastics Engineers

Simulation prediction of the fiber breakage history in regular and barrier structure screws in injection molding

In recent years, the use of long fiber‐reinforced thermoplastics (LFRT) has become one of the most popular materials in lightweight applications. However, the microstructure of the fiber inside the plastic matrix is quite complex, making it hard to fully control the fiber effect in the injection molding process. On the other hand, the screw structure and operation will affect the residual fiber length significantly. However, the mechanism of how the screw influences the fiber breakage is still not yet clear. Thus, in this study, we apply the screw plastication in the injection molding process to investigate the fiber microstructure mechanism. The results show that more severe fiber breakage occurs when the compression force increases abruptly. Generally speaking, the breakage increases from the compression to the metering section. One effective method to reduce the fiber breakage is to increase the channel depths in both the feeding and the metering sections while taking the plastic melt quality into consideration. Moreover, the fiber breakage phenomena for two types of fibers are also investigated. Evidently, carbon fiber is easier to be broken. Its length distribution has a higher peak at the exit of the screw. This discovery is consistent with the experimental results of the current literature studies. POLYM. ENG. SCI., 58:452–459, 2018. © 2017 Society of Plastics Engineers

A novel fiber length measurement technique for discontinuous fiber‐reinforced composites: A comparative study with existing methods

The residual fiber length in a molded part is one of the most important microstructural properties of discontinuous fiber‐reinforced composites. While there have been several research studies characterizing the process‐induced fiber length reduction, the measurement procedures vary substantially, calling into question the comparability of reported results. This article introduces a newly developed measurement procedure that aims to provide accurate, repeatable, robust, and time efficient fiber length analyses. A comprehensive study of measurement techniques was performed comparing commercially available systems and the conventional approach of measuring the fiber length manually. The results emphasize the need for a standardized procedure to characterize the fiber length distribution and the risk of generating inadequate results through improper sample preparation. The developed measurement technique was tested and compared for an experimental study of fiber breakage in injection molding. For a simple plaque geometry, the residual fiber length along the flow path was obtained for a long glass fiber‐reinforced polypropylene at 30 and 40%wt for varying process conditions. The new measurement technique showed accurate and repeatable results. The results of the injection molding study showed that screw speed and back pressure are important factors that drive fiber breakage. An increase in back pressure from 13 to 50 bar and screw speed from 27 to 35 rpm reduces the weight‐average fiber length by 37.5%. POLYM. COMPOS., 39:4058–4070, 2018. © 2017 Society of Plastics Engineers

Effect of discontinuous long polyimide fiber on mechanical properties, fracture morphology, and crystallization behaviors of polyamide-6 matrix composites

This work has conducted an extensive investigation on the effect of discontinuous long polyimide (PI) fiber on the mechanical properties, fracture morphology, and crystallization behaviors of polyamide-6 (PA6) matrix composites. A series of PA6 matrix composites with different contents of PI fiber were prepared through a standard melt-pultrusion process. The resulting composite specimens not only achieved a prominent reinforcement but also obtain a significant improvement in impact toughness. It is highlighted that the composites achieved a remarkable increase in Izod impact strength by a factor of five compared to pure PA6 when 12 wt% of PI fiber was incorporated. Moreover, the tensile strength of the composites reached 143 MPa at a fiber content of 18 wt%. The mechanical properties could be well predicted by the Cox-Krenchel model, but a negative deviation in experimental data was observed at high fiber concentrations due to the decrease of residual fiber length and fiber aggregation. The morphologic observation of fracture surface indicated that fiber pullout was a major mechanism for tensile failure as a result of long PI fiber-reinforcing effectiveness, and it was also the predominant energy absorption mechanism for the impact fracture of composite specimens. The presence of long PI fiber not only enhanced the crystallinity of PA6 matrix but also induced a well-defined transcrystalline layer on the fiber surface due to its high nucleating ability.

Long range surface plasmon resonance sensor based on side polished fiber with the buffer layer of magnesium fluoride

In this paper, a theoretical analysis of figure of merit (FOM) of a surface plasmon resonance (SPR) sensor with a buffer layer of magnesium fluoride has been carried out. While the FOM is the ratio of sensitivity and full width at half maximum and it is the measurement index for the SPR performance. The numerical simulation is based on side polished single mode fiber SPR sensor with the 66.5 μm residual fiber thickness and Drude model of metal with the 50 nm gold film thickness. Meanwhile, the comparisons for traditional surface plasmon resonance sensor, symmetrical surface plasmon resonance sensor and long range surface plasmon resonance sensor have performed differently for the FOM. The effect of sensitivity, full width at half maximum and transmittance depth has also been studied. All these studies, lead to a significant analysis to achieve the best possible design of a fiber optic SPR sensor with maximum FOM while the thickness of buffer layer is 100 nm. This design is expected to play an important role on chemical sensing and biological sensing.

Organosolv extraction of softwood combined with lignin-to-liquid-solvolysis as a semi-continuous percolation reactor

As part of a concept for a continuous biorefining process, a fractionation procedure for lignocellulosic biomass based on flow-through organosolv lignin solubilisation has been developed and tested. Lignin is removed from the biomass in a continuous flow-through system, producing a dissolved lignin fraction and a residual fibre fraction rich in cellulose. A solvent system comprising ethanol, water and sulfuric or formic acid as catalyst is tested over a 413–468 K temperature range. Process conditions that are suitable for fractionation of softwood from Norway spruce are determined using an experimental design. The best conditions give yields up to 86% of the initially determined lignin mass, leaving a clean fibre residue that corresponds to 67% of the initial cellulose mass. The produced lignin fraction can be converted by formic acid assisted solvolysis to a liquid comprising mostly methoxy-phenols at nearly 90% mass yield. The results show that the continuous flow fractionation of lignocellulosic biomass is a promising route for biorefinery processing.

Removal of toxic Congo red dye from water employing low-cost coconut residual fiber.

The coconut residual fiber (CRF) is the major byproduct obtained during production of virgin coconut oil. Its application as a biosorbent for adsorption of Congo red was investigated. The CRF was subjected to different pretreatments, namely, pressure cooking, hexane treatment, acid treatment and their combinations. The pretreatment of CRF with the combination of hexane, acid, and pressure cooking resulted in the highest degree of adsorption. The equilibrium data were analyzed and found to fit best to both Langmuir and Freundlich isotherms. Thermodynamic parameters such as standard free energy (ΔG0 kJ mol-1), standard enthalpy (ΔH0, kJ mol-1) and standard entropy (ΔS0, kJ mol-1 K-1) of the systems were calculated by using the Langmuir constant. The ΔG0, ΔH0 and ΔS0 were found to be 16.51 kJ mol-1, -19.39 kJ mol-1 and -0.12 kJ mol-1 K-1, respectively, at 300 K. These thermodynamic parameters suggest the present adsorption process to be non-spontaneous and exothermic. The adsorption process was observed to follow pseudo-second-order kinetics. The results suggest that CRF has potential to be a biosorbent for the removal of hazardous material (Congo red dye) with a maximum adsorption capacity of 128.94 mg g-1 at 300 K.

Residual fibre lung burden among patients with pleural mesothelioma who have been occupationally exposed to asbestos

ObjectivesTo evaluate the lungs asbestos fibres concentration in participants with malignant pleural mesothelioma (MPM) who have been occupationally exposed.MethodsThe lung samples were obtained from pleuropneumonectomies or autopsies of 271 male...

In vitro kinetic parameters of marandu palisadegrass associated with nonfiber carbohydrates

This study aimed to evaluate the effects of different levels (0, 10, 20 and 30%) of starch or glucose associated with marandu palisadegrass (Urochloa brizantha cv. Marandu) on its kinetic parameters and fiber digestion by the in vitro gas production technique. The experiment was arranged in a completely randomized design, with four treatments and six replications for each energy source. The marandu palisadegrass associated with nonfiber carbohydrate levels was incubated in 120 ml bottles, with McDougall buffer and rumen fluid from two rumen-cannulated sheep. Readings were taken of gas pressure within the bottle, and two vials were removed at 24, 48 and 96 hours (h) to assess residual neutral detergent fiber (NDF). The one-pool logistic model was used to estimate the kinetic parameters for pure forage and forage associated with starch, however it was necessary to use the two-pools model when glucose was added. Each 1% of added starch promoted a linear increase in total gas production of 0.2254 ml and a decrease in lag time of 0.2451 h, but did not affect the digestion rate. Glucose levels had a quadratic effect on digestion rate and lag time, with a minimum estimated value for digestion rate of 0.01689 h-1 at a glucose level of 10.07% and a minimum lag time of zero. Starch levels caused a linear reduction in NDF digestion of 0.296% only at 24 h, while glucose levels linearly reduced the NDF digestion in all evaluated times (0.3269, 0.4171 and 0.2340% at 24, 48 and 96 h, respectively). Glucose levels promoted different effects on the in vitro gas production kinetic parameters of marandu palisadegrass compared to starch supplementation, highlighting the prolonged negative effects on NDF digestion.

Interface Characterization in Fiber-Reinforced Polymer–Matrix Composites

A novel methodology is presented and applied to measure the shear interface strength of fiber-reinforced polymers. The strategy is based in fiber push-in tests carried out on the central fiber of highly-packed fiber clusters with hexagonal symmetry, and it is supported by a detailed finite element analysis of the push-in test to account for the influence of hygrothermal residual stresses, fiber constraint and fiber anisotropy on the interface strength. Examples of application are presented to determine the shear interface strength in carbon and glass fiber composites reinforced with either thermoset or thermoplastic matrices. In addition, the influence of the environment (either dry or wet conditions) on the interface strength in C/epoxy composites is demonstrated.

Viscoelastically prestressed polymeric matrix composites: An overview

Elastically prestressed polymeric matrix composites exploit the principles of prestressed concrete, i.e. fibres are stretched elastically during matrix curing. On matrix solidification, compressive stresses are created within the matrix, counterbalanced by residual fibre tension. Unidirectional glass fibre elastically prestressed polymeric matrix composites have demonstrated 25–50% improvements in impact toughness, strength and stiffness compared with control (unstressed) counterparts. Although these benefits require no increase in section dimensions or weight, the need to apply fibre tension during curing can impose restrictions on processing and product geometry. Also, fibre–matrix interfacial creep may eventually cause the prestress to deteriorate. This paper gives an overview of an alternative approach: viscoelastically prestressed polymeric matrix composites. Here, polymeric fibres are subjected to tensile creep, the applied load being removed before the fibres are moulded into the matrix. Following matrix curing, viscoelastic recovery mechanisms cause the previously strained fibres to impart compressive stresses to the matrix. Since fibre stretching and moulding operations are decoupled, viscoelastically prestressed polymeric matrix composite production offers considerable flexibility. Also, the potential for deterioration through fibre–matrix creep is offset by longer term viscoelastic recovery mechanisms. To date, viscoelastically prestressed viscoelastically prestressed polymeric matrix composites have been produced from fibre reinforcements such as nylon 6,6, ultra-high molecular weight polyethylene and bamboo. Compared with control counterparts, mechanical property improvements are similar to those of elastically prestressed polymeric matrix composites. Of major importance, however, is longevity: through accelerated ageing, nylon fibre-based viscoelastically prestressed viscoelastically prestressed polymeric matrix composites show no deterioration in mechanical performance over a duration equivalent to ∼25 years at 50℃ ambient. Potential applications include crashworthy and impact-absorbing structures, dental materials, prestressed precast concrete and shape-changing (morphing) structures.