Fiber Chemical Treatment Research Articles

Heat transfer coefficient of flowing wood pulp fibre suspensions to monitor fibre and paper quality

Abstract Heat transfer measurements were obtained for a range of suspensions of wood pulp fibre flowing through a pipeline. Data were generated over a selected range of flow rates and temperatures from a specially built flow loop. It was found that the magnitude of the heat transfer coefficient was above water at equivalent experimental conditions at very low fibre concentrations, but progressively decreased until it was below water at slightly higher concentrations. It was found that the heat transfer was affected by varying fibre properties, such as fibre length, fibre flexibility, fibre chemical and mechanical treatment, the variation of fibres from different parts of the tree as well as the different pulping methods used to liberate the fibres from the wood structure. Heat transfer coefficient was decreased with the increasing of fibre flexibility as found by previous workers. In the present investigation properties of fibre and paper are correlated with heat transfer to suspensions of fibres. Variations in fibre characteristics can be monitored in flowing suspension of fibres by measuring heat transfer coefficient and using those measurements to adjust the degree of fibre refining treatment so that papers made from those fibres are more uniform, more consistent and within product specification.

Effect of Redmud Particulates on Mechanical Properties of BFRP Composites

This article reports the effective usage of redmud (RM), an industrial waste, as a novel filler in polymer matrix. The composite has been fabricated with redmud as secondary reinforcement in banana fiber reinforced polyester (BFRP) using compression molding technique. The mechanical properties such as tensile, flexural and impact strength have been studied for different fiber weight percentage, weight percentage of red mud and chemical treatment of fiber. It is observed that the addition of 10 wt percent of redmud improves the impact and flexural properties for both NaOH, silane treated and untreated banana fiber but there is a decreased trend for tensile strength. It is also found that banana fiber particulate composites have superior mechanical properties than the banana/polyester. Addition of redmud to the banana fiber decreases the moisture absorption of the composites. The studies of the scanning electron microscopy (SEM) have been done to know the fracture mechanism.

The Effect of Varying Fiber Characteristics on the Simultaneous Measurement of Heat and Momentum Transfer to Flowing Fiber Suspensions

Heat transfer and pressure loss measurements were obtained simultaneously for a range of wood pulp fiber suspensions flowing in a pipeline. Data were obtained over a selected range of flow rates and temperatures from a specially built flow loop. It was found that the magnitude of the heat transfer coefficient was above water at equivalent experimental conditions and at very low fiber concentrations, but progressively decreased until it was below water at slightly higher concentrations. Similar trends were obtained for the pressure drop measurements obtained simultaneously, showing good correspondence between the two sets of data. It was found that both heat and momentum transfer are affected in a closely similar way by varying fiber properties, such as fiber length, fiber flexibility, fiber chemical and mechanical treatment, the variation of fibers from different parts of the tree, as well as the different pulping methods used to liberate the fibers from the wood structure. Drag reduction increased and heat transfer coefficient decreased with increasing fiber flexibility as found by previous workers.

Processing and Characterization of Epoxy/Luffa Composites: Investigation on Chemical Treatment of Fibers on Mechanical and Acoustical Properties

This study focuses on the development of epoxy/luffa composites and the investigation of their mechanical and acoustical properties. The fibers underwent an alkalization treatment, and its effects on the mechanical and sound absorption properties of the composites were measured utilizing a universal testing machine and two-microphone transfer function impedance tube methods. The effects of chemical modifications on the fibers were studied using a scanning electron microscope (SEM). The thermal analyses of composites were conducted using thermo-gravimetric analysis (TGA). The composite’s functional group was identified and evaluated using Fourier transform infrared spectroscopy (FTIR). The sound absorption coefficient of untreated and treated composites across a range of frequencies was very similar. Untreated composites appeared to perform better than those that were treated. Compared with untreated fiber composites, there was an improvement in the tensile strength of the treated fiber composites. The SEM characterization showed that the alkaline treatment changed the morphology of the fibers, resulting in a decrease in the sound absorption coefficients of the composites. The thermal characterization of composites showed that dehydration and degradation of lignin occurred in a temperature range of 40 to 260 °C, and the maximum percentage of cellulose was found to decompose at 380 °C.

Improvement of physico-mechanical properties of coir-polypropylene biocomposites by fiber chemical treatment

In preparing polymer–matrix composites, natural fibers are widely used as “reinforcing agents” because of their biodegradable characteristic. In present research, coir fiber reinforced polypropylene biocomposites were manufactured using hot press method. In order to increase the compatibility between the coir fiber and polypropylene matrix, raw coir fiber was chemically treated with basic chromium sulfate and sodium bicarbonate salt in acidic media. Both raw and treated coir at different fiber loading (10, 15 and 20 wt%) were utilized during composite manufacturing. During chemical treatment, hydrophilic –OH groups in the raw coir cellulose were converted to hydrophobic –OH−Cr groups. Microstructural analysis and mechanical tests were conducted. Scanning electron microscopic analysis indicates improvement in interfacial adhesion between the coir and polypropylene matrix upon treatment. Chemically treated specimens yielded the best set of mechanical properties. On the basis of fiber loading, 20% fiber reinforced composites had the optimum set of mechanical properties among all composites manufactured.

Effects of chemical modifications and MMT nanoclay addition on transport phenomena of naturally woven coconut sheath/polyester nanocomposites

Studies on the behavior of molecular transport properties such as thermal conductivity, gas permeability, volume and surface resistivity have been carried out for the naturally woven coconut sheath (CS) fiber reinforced composites with the addition of nanoclay and chemical treatment of fiber. The compression molding technique was used to fabricate the coconut sheath/clay reinforced hybrid composites. The morphological studies such as X-ray diffractogram (XRD), transmission electron microscopy (TEM) and scanning electron microscopy (SEM) have been carried out for polyester nanocomposites and coconut sheath fiber. The decreased gas permeability, thermal conductivity and volume and surface resistivity have been observed with increasing the weight percentage of nanoclay in polyester matrix. In chemical modifications, the alkali and silane treated coconut sheath reinforced composites have shown great influence on the transport properties due to the increasing hydrophilic nature by the topographical changes at the fiber surface. Dielectric strength has also been reported in this paper for all types of composites. Infra-red (IR) spectra have also been taken to study the physical and chemical structural changes of treated coconut sheath.

The effect of fibre chemical treatment on the steel fibre/cementitious matrix interface

► Enhanced bonding was achieved via treatment of steel fibres with ZnPh conversion. ► ZnPh crystals precipitation resulted into a rough surface of the steel fibres. ► ZnPh treatment led to significant increase in pullout energy. ► ZnPh treatment has a prominent effect, when mechanical interlocking is negligible. ► Optimum fibre configuration can be chosen based on the fibre surface contact area. This paper aims to study the interfacial bonding between steel fibres and cement-based matrix. The fibres were treated chemically using a zinc phosphate conversion to achieve enhanced bonding with the mortar matrix. In order to gain a better perspective on the effect of chemical treatment different fibre parameters were considered in this research, such as the fibres shape, length and diameter. In this respect, single-sided fibre pullout tests were conducted on treated as well as on as received (untreated) fibres of hooked-end, straight and undulated shape. The analysis of the experimental results revealed that the fibre shape is of great importance since it contributes to mechanical interlocking that prevail during the pullout of the fibres. Chemical treatment was also shown to play an important role on the fibre–matrix interface especially when mechanical interlocking is absent. Treated fibres exhibited a modified surface with a rough topology caused by precipitation of ZnPh crystals on the fibre. Optimum fibre configuration for maximum pullout performance can be chosen based on the fibre surface contact area, since the pullout load and pullout energy is directly related to this property.

Helium gas barrier and water absorption behavior of bamboo fiber reinforced recycled polypropylene

Helium gas permeability and water absorption behavior of the recycled polypropylene/short bamboo fiber composite membrane were investigated. The effects of short bamboo fiber content and fiber chemical treatment on gas permeability and water absorption properties of composites have been examined. Our research showed that the solubility coefficient of helium increased as the fiber content of the bamboo increases but the diffusivity coefficient seemed to decrease with increasing amount of bamboo fiber in the composite formulation due to the poor adhesion between bamboo fiber and polymer matrix. The structure of recycled polypropylene/bamboo fibers have also investigates by X-ray diffraction technique. The chemical treatment of the bamboo fiber by alkali solution increased fiber surface roughness within the composite; in consequence, a more homogeneous dispersion of these fibers appears in the polymer matrix. The process of absorption of water was found to follow the kinetics and mechanisms described by Fick’s theory. A considerable loss in mechanical properties of the water-saturated samples after 3 months of aging in water was observed and this reduction could be delayed by fiber chemical treatment. This study provided the useful information about the behavior of recycled polypropylene/bamboo fiber composite materials during their service life time.

Morphological and thermal properties of maize fiber composites

Maize stalk has become one of the major sources of fibers from the agricultural residues. Use of these fibers as a reinforcement in the polymer is described in this paper. The present work is focused on establishing the properties such as physical, chemical, morphological structure and thermal properties of maize stalk fiber using different characterization techniques. Simple hand layup method was followed for processing the composite material. Chemical treatments of fibers were carried out to study the interaction of fibers with the matrix. The results revealed that maize fibers can also be used as a traditional fiber as reinforcement in a natural fiber reinforced composite materials.

The Effect of Chemical Treatment of Cellulose with Epoxidized Soybean Oil (ESO) on the Properties PVC/Cellulose Composites

The adhesion between vegetable fibres and the polymeric matrix remains one of the technological bolts of the development of composites. Indeed cellulose, the principal constituent of vegetable fibres, is not generally compatible with thermoplastic matrices. Many studies thus focus on the improvement of these properties, in particular by the means of physical or chemical treatments of fibres. The objective of this work was the chemical modification of cellulose by epoxidized soybean oil to improve compatibility between the cellulose and the matrix. The effect on the physico-mechanical properties of the PVC/cellulose composites containing 10 to 30% treated cellulose was studied. The resultant composites were characterized various tests (mechanical, thermal and morphological).

Effect of Fiber Esterification on Fundamental Properties of Oil Palm Empty Fruit Bunch Fiber/Poly(butylene adipate-co-terephthalate) Biocomposites

A new class of biocomposites based on oil palm empty fruit bunch fiber and poly(butylene adipate-co-terephthalate) (PBAT), which is a biodegradable aliphatic aromatic co-polyester, were prepared using melt blending technique. The composites were prepared at various fiber contents of 10, 20, 30, 40 and 50 wt% and characterized. Chemical treatment of oil palm empty fruit bunch (EFB) fiber was successfully done by grafting succinic anhydride (SAH) onto the EFB fiber surface, and the modified fibers were obtained in two levels of grafting (low and high weight percentage gain, WPG) after 5 and 6 h of grafting. The FTIR characterization showed evidence of successful fiber esterification. The results showed that 40 wt% of fiber loading improved the tensile properties of the biocomposite. The effects of EFB fiber chemical treatments and various organic initiators content on mechanical and thermal properties and water absorption of PBAT/EFB 60/40 wt% biocomposites were also examined. The SAH-g-EFB fiber at low WPG in presence of 1 wt% of dicumyl peroxide (DCP) initiator was found to significantly enhance the tensile and flexural properties as well as water resistance of biocomposite (up to 24%) compared with those of untreated fiber reinforced composites. The thermal behavior of the composites was evaluated from thermogravimetric analysis (TGA)/differential thermogravimetric (DTG) thermograms. It was observed that, the chemical treatment has marginally improved the biocomposites’ thermal stability in presence of 1 wt% of dicumyl peroxide at the low WPG level of grafting. The improved fiber-matrix surface enhancement in the chemically treated biocomposite was confirmed by SEM analysis of the tensile fractured specimens.

Vegetable fibres from agricultural residues as thermo-mechanical reinforcement in recycled polypropylene-based green foams

Novel lightweight composite foams based on recycled polypropylene reinforced with cellulosic fibres obtained from agricultural residues were prepared and characterized. These composites, initially prepared by melt-mixing recycled polypropylene with variable fibre concentrations (10-25 wt.%), were foamed by high-pressure CO(2) dissolution, a clean process which avoids the use of chemical blowing agents. With the aim of studying the influence of the fibre characteristics on the resultant foams, two chemical treatments were applied to the barley straw in order to increase the α-cellulose content of the fibres. The chemical composition, morphology and thermal stability of the fibres and composites were analyzed. Results indicate that fibre chemical treatment and later foaming of the composites resulted in foams with characteristic closed-cell microcellular structures, their specific storage modulus significantly increasing due to the higher stiffness of the fibres. The addition of the fibres also resulted in an increase in the glass transition temperature of PP in both the solid composites and more significantly in the foams.

Effects of Processing Temperature and Chemical Treatment on Tensile Strength of Kenaf Fiber - Reinforced Polypropylene Waste Composites

In this research, the influence of processing temperatures and fiber chemical treatments to mechanical properties of polypropylene (PP) waste – kenaf fiber composites was investigated. Results from experimental and theoretical calculation of composite tensile strength were compared. The composites were made of PP wastes and unidirectional kenaf fiber, and manufactured by hot press molding. The processing temperature variations were 175 oC, 185oC and 195 oC. The chemical treatment used were alkaline and permanganate treatment. Kenaf fiber – PP composites were successfully made with the void volume fraction less than 5%, maximum fiber volume fraction 48% and maximum longitudinal tensile strength 110 MPa or 238% higher than PP’s strength. For non- and alkali treated fiber composites, 185oC was the optimum processing temperature. Elevated processing temperature up to 195oC could decrease composite strength due to the degradation of fiber-matrix interface. The effect of permanganate treatment did not significantly affect the composites strength. However, the improvement of interfacial properties at elevated temperature was found by the use of permanganate treatment.

Relationship between fiber chemical treatment and properties of recycled pp/bamboo fiber composites

This article reports the preparation of recycled polypropylene (RPP)/bamboo fiber (BF) composite via direct melt blends using a twin screw extruder. The effects of the chemical treatment of BF surface (alkaline and acetylation) on fiber structure and composite mechanical, thermal, rheological properties have been investigated. We showed that alkali treatment increases the contact surface of BF within composites, resulting in a more homogenous dispersion of fibers in the polymer matrix. Alkali treatment improves mechanical properties such as tensile strength as well as the Charpy impact strength. Reinforced composites obtained with acetylated BF show better mechanical properties due to grafting of acetyl groups onto the cellulose fiber surface and thus improve compatibility between BF and matrix. The rheological properties of RPP/BF composites depending on the BF content and treatment methods are also analyzed. Predominant factors that influence the properties of relevant materials are identified. Maleic anhydride grafted polypropylene is used as a compatibilizer to improve the adhesion between the cellulosic phase and the RPP matrix.

THE EDITION EFFECT OF NATURAL FIBERS ON POLYMERIC MATERIALS AND STUDY SOME OF THERMAL AND MECHANICAL PROPERTIES

This research has been done by reinforcing the matrix (polyester) resin with natural material (frond palm). The fibers were exposure to chemical treatment before reinforcement.Different volume fractions were used (0%, 15%, 20%). After preparation of composite material some of the physical properties have been studied of samples preparation. They were Tensile strength test, Impact test, and Thermal conductivity. The thermal conductivity was studied, the values of thermal conductivity were increased with increasing of volume fraction of all specimens and also the tensile strength and flexural strength were decreased with increasing volume fraction of fibers, while the impact strength was increased with volume fraction 15% but with continuouity of reinforcement, the impact strength wasdecreased, and also the chemical treatment of fibers improved the mechanical and thermal properties.

Preparation and characterization of micro- and nano-fibrils from jute

In order to prepare micro- and nano-fibrils from jute, the binder has to be cleaned off. A new technique including chemical (room temperature alkaline, acid steam, and 80 °C alkaline) and physical (high pressure steam) treatments of natural fibers was developed. The effects of chemical and physical treatments on the morphological development of jute fibers from micro- to nano-scale were observed by using scanning electron microscopy (SEM). This novel natural fibers treatment technology has two advantages compared with others. One is the long strands of natural fibers keep their length by special acid steam treatment, but the traditional acid solution treatment makes the length of natural fibers short. Another one is the high pressure steam treatment that made jute fibers nano-fibrils. The thermal property of untreated and treated fibers was determined by using thermogravimetric analysis (TGA) which indicated that the thermal stability of the jute fibers was enhanced after treatments. The lignin acted as binder was mainly removed by analyzing solid residues using fourier transform infrared spectrometer (FTIR).

Influence of various chemical treatments on the interactions between hemp fibres and a lime matrix

In this paper, results presented concern both the chemical and physical behaviours of hemp fibres in lime-based mineral matrix in order to better understand the role of chemical modifications of cellulosic fibres in the evolution of the macroscopic properties, essentially mechanical ones, of such composite materials. The role of fibres surface treatment has been also studied through various chemical treatments applied on hemp fibres. In a first step, the influence of such treatments on the fibre characteristics has been investigated by several means, such as scanning electron microscopy, thermal analysis, X-ray diffraction and FTIR spectroscopy, in order to evaluate their consequences on the fibre behaviour itself. Secondly, an attempt to characterise the influence of the various chemical treatments of fibres on the mechanical behaviour of hemp reinforced lime-based composites has been completed by a three points bending testing campaign. According to the results, it seems that the modifications induced by specific chemical treatments (EDTA, NaOH) on fibres play a major role in the strengthening of the lime/fibres interface but also in the improvement of the overall stiffness of the composite (with respect to the one reinforced by untreated fibres) most probably related to a specific stiffening process of the fibre itself.

Comparison of the thermal degradation of natural, alkali‐treated and silane‐treated hemp fibers under air and an inert atmosphere

AbstractTo estimate the contribution of all major components to the thermal properties of natural hemp fiber bundles, the thermal decomposition of hemp fibers following several chemical treatments was studied by the differential thermogravimetric analysis (DTA/TGA). Contrary to what was observed with measurements conducted under air, the thermal degradation of all major hemp fiber components (pectins, hemicellulose, cellulose, and lignin principally) could be easily detected and deconvoluted under inert atmosphere. The intensity of the TGA peaks observed at 235°C (characteristics of pectin) and at 265°C (characteristics of hemicellulose) decreased after all fiber chemical treatments. This resulted in an overall increase of the cellulose percentage. Based on the onset temperature of DTA, it was found that the thermal stability decreased in the following order: NaOH‐treated fibers, silane‐treated fibers, solvent extracted fibers (water/ethanol mixture, 20/80 v/v), and untreated hemp fibers. Moreover, the difference of the mass loss (%) between TGA under argon of silane‐treated fibers and untreated fibers showed that some silane molecules were chemically attached to hemp fiber bundles. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009

Effect of Fiber Content and Chemical Treatment on the Thermal Properties of Spartium junceum Fiber-Reinforced Polypropylene Composites

The thermal and crystallization behavior of PP/Spartium junceum fiber composites were studied by thermogravimetry (TGA) and differential scanning calorimetry (DSC). The surface modification of Spartium junceum fibers was carried out using silane coupling agents in order to improve the interfacial adhesion between the fiber and the matrix. The effects of fiber content and chemical treatment on thermal properties were evaluated. It was found that Spartium junceum fiber degraded before the PP matrix but the thermal stability of the PP/Spartium junceum fiber composites was higher than those of the fiber and the matrix. DSC measurements showed that the incorporation of Spartium junceum fiber caused an increase in the crystallinity of the matrix. These effects have been attributed to the fact that the surfaces of Spartium junceum fibers act as nucleating agents for the crystallization of the polymer, promoting the growth and the formation of transcrystalline regions around the fibers.

Preparation and characterization of poly(vinyl chloride)/virgin and treated sisal fiber composites

AbstractMechanical property changes, thermal stability, and water absorption capacity of poly(vinyl chloride) (PVC)/sisal fiber composites were assessed with respect to the effect of maleic anhydride chemical treatments of the sisal fiber, for five different sisal fiber contents, varying from 0 to 30% by weight in the composite. The composites prepared with the untreated sisal exhibited higher tensile modulus and hardness than the unloaded resin, while elongation and tensile strength were reduced. The deterioration in the mechanical properties of PVC blended with sisal fiber is attributed to the presence of moisture, interfacial defects at the fiber and polymer interface, and fiber dispersion in the PVC matrix. The amount of absorbed water is a function of the amount of fiber in the composite (F0 = 0 phr, F5 = 0.77 phr, and F20 = 4.83 phr). The comparison of the results of characterization of F5, F20, and F30 formulations prepared with the untreated fibers and the treated ones showed a reduction in absorbed water after the chemical treatment of fiber with maleic anhydride (F0 = 0 phr, F5 = 0.28 phr, and F20 = 2.99 phr), thus improving the mechanical properties of composites prepared with the treated sisal. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 3630–3636, 2007