Addition Of Cellulose Fibers Research Articles

The properties of potato and cassava starch films combined with cellulose fibers and/or nanoclay

The aim of this study was to develop and evaluate films produced from potato and cassava starches, reinforced with cellulose fibers and/or nanoclay. The films were elaborated with 4% starch, 30% glycerol, 20% cellulose fiber, and/or 5.0% nanoclay. The films were evaluated by physical, mechanical, and water vapor barriers, and morphological properties. The addition of nanoclay and cellulose simultaneously increased the tensile strength from 12.03 to 17.75 MPa and decreased the elongation from 13.81 to 0.94% of the potato starch films when compared to films without addition of these reinforcements. The addition of cellulose fibers and/or nanoclay increased the tensile strength of the cassava starch films. The water vapor permeability (WVP) of the films decreased with the addition of reinforcing agents, and the lowest WVP values were presented when cellulose and nanoclay were added simultaneously to the starch films. A synergistic effect between the cellulose and the nanoclay in the constitution of the film promoted a lower WVP value. The addition of cellulose increased the water solubility from 14.7 to 19.6% of the potato starch films. The addition of reinforcement agents in potato starch films produced more resistant films with a moderate solubility, thus can be used as a biodegradable sachet to release systems.

Effects of cellulose fiber with different fiber length on rheological properties of wheat dough and quality of baked rolls.

Powdered cellulose is often used in cereal processing industry. The effects of partial replacement (0.5%, 1%, 2% and 5%) of wheat flour by cellulose fiber with different fiber length (80, 120 and 220 µm) on rheological properties of wheat dough and qualitative parameters of baked rolls were studied. Sensory evaluation of baked products was also performed. Mixing and pasting properties of dough were determined by Mixolab. Generally, cellulose-enriched dough was characterized with higher water absorption, dough stability and parameters C2 and C3. Moreover, it was found that parameters C4 and C5 increased with increasing cellulose fiber length. From the results, it was also concluded that the physical parameters of baked rolls containing cellulose were reduced. It was also observed that the incorporation of cellulose fiber with shorter fiber length concluded in lower rolls volume compared to cellulose fiber with long fiber length. Texture analyses showed that the firmness of rolls containing cellulose at the substitution level 5% was significantly higher than those of the control, whereas the springiness of wheat rolls was not significantly affected. It was also recorded that the firmness and cohesiveness of baked rolls were higher after the addition of cellulose fiber with shorter fiber length. Sensory evaluation indicated that baked rolls with cellulose addition up to 1% were comparable with control rolls. Results also showed that higher levels of cellulose significantly decreased crust, taste, color and porosity of rolls.

Morphological, mechanical, barrier and properties of films based on acetylated starch and cellulose from barley.

Biodegradable films of native or acetylated starches with different concentrations of cellulose fibers (0%, 10% and 20%) were prepared. The films were characterized by morphological, mechanical, barrier, and thermal properties. The tensile strength of the acetylated starch film was lower than those of the native starch film, without fibers. The addition of fibers increased the tensile strength and decreased the elongation and the moisture of native and acetylated starches films. The acetylated starch film showed higher water solubility when compared to native starch film. The addition of cellulose fibers reduced the water solubility of the acetylated starch film. The films reinforced with cellulose fiber exhibited a higher initial decomposition temperature and thermal stability. The mechanical, barrier, solubility, and thermal properties are factors which direct the type of the film application in packaging for food products. The films elaborated with acetylated starches of low degree of substitution were not effective in a reduction of the water vapor permeability. The addition of the cellulose fiber in acetylated and native starches films can contribute to the development of more resistant films to be applied in food systems that need to maintain their integrity. © 2016 Society of Chemical Industry.

Films based on oxidized starch and cellulose from barley

Starch and cellulose fibers were isolated from grains and the husk from barley, respectively. Biodegradable films of native starch or oxidized starches and glycerol with different concentrations of cellulose fibers (0%, 10% and 20%) were prepared. The films were characterized by morphological, mechanical, barrier, and thermal properties. Cellulose fibers isolated from the barley husk were obtained with 75% purity and high crystallinity. The morphology of the films of the oxidized starches, regardless of the fiber addition, was more homogeneous as compared to the film of the native starch. The addition of cellulose fibers in the films increased the tensile strength and decreased elongation. The water vapor permeability of the film of oxidized starch with 20% of cellulose fibers was lower than the without fibers. However the films with cellulose fibers had the highest decomposition with the initial temperature and thermal stability. The oxidized starch and cellulose fibers from barley have a good potential for use in packaging. The addition of cellulose fibers in starch films can contribute to the development of films more resistant that can be applied in food systems to maintain its integrity.

Regenerated cellulose fibre reinforced casein films: Effect of plasticizer and fibres on the film properties

The idea of using man-made cellulosic fibres as reinforcement for casein films in this study was inspired by their well defined fibre diameter and availability in large quantity, eventually leading to a homogeneous high quality composite at low cost. The casein biofilms were fabricated by solution casting from an aqueous alkaline solution of the bovine milk protein casein in the presence of glycerol as a plasticizer, and the fibre-reinforced biocomposites were prepared by the addition of regenerated cellulose fibre to the casein casting solution with various amounts of glycerol. The effects of glycerol content and cellulose fibre reinforcements on the mechanical, thermal and physiological properties were characterized. The results showed that increasing glycerol content decreased the film strength, Young’s modulus and thermal stability with a gradual increase in the elongation. However, the tensile properties were noticeably improved when reinforced with cellulose fibre. The composite with 20 wt% glycerol and 20 wt% cellulose fibre showed the maximum tensile strength of 23.5 MPa and Young’s modulus of 1.5 GPa. The corresponding values for the composite with 30 wt% glycerol and the same fibre content were 15.1 MPa and 0.9 GPa, which were 2.3- and 3.2-fold higher compared to 30 wt% glycerol plasticized film. The thermal analysis revealed that the glass transition temperature and the thermal stability were decreased when the glycerol content was increased. Addition of cellulose fibres increased the glass transition temperature as well as the thermal stability. The gel electrophoresis (SDS-PAGE) analysis indicated that there was no significant decrease in the molecular weight of the casein protein during sample preparation. Scanning electron microscopy showed that the obtained composites with low glycerol content had adequate interfacial bonding, and Fourier transform IR spectroscopy confirmed the formation of molecular interactions between the cellulose fibres and the casein. Open image in new window

Strategies to improve the mechanical properties of high-density polylactic acid foams

In this study, different strategies to improve the mechanical properties of physically foamed high-density polylactic acid sheets were examined to produce polylactic acid foam sheets with tailor-made mechanical properties. The first part was the determination of the effect of different blowing agents (CO2 and N2) on the foam morphology. The second part of the study was the modification of the formulation. For this purpose, both a linear and a branching chain extender and a thermoplastic elastomer were used to improve the elongational properties (tensile modulus and strain at break) of the polylactic acid foam sheets. Additionally, the effect of the addition of cellulose fibers on the foam morphology and the mechanical properties was investigated. All experiments were carried out on a laboratory flat-film line. This extrusion line consists of a 30-mm single-screw extruder attached with a 250-mm flat sheet die. The results show a strong influence of the material formulation on the mechanical properties of the high-density foam sheets. Both the mechanical properties and foam morphology could be improved by the right material formulation. The addition of the thermoplastic elastomer leads to a better foam morphology and also to a reduced brittleness of the foam sheets. Furthermore, it could be demonstrated that cellulose fiber can be used as a nucleating agent for polylactic acid but causes a further decrease in the strain at break.

Biocomposite cellulose-alginate films: Promising packaging materials

Biocomposite films based on cellulose and alginate were produced using unmodified birch pulp, microfibrillated cellulose (MFC), nanofibrillated cellulose (NFC) and birch pulp derivate, nanofibrillated anionic dicarboxylic acid cellulose (DCC), having widths of fibres ranging from 19.0μm to 25nm as cellulose fibre materials. Ionically cross-linked biocomposites were produced using Ca2+ cross-linking. Addition of micro- and nanocelluloses as a reinforcement increased the mechanical properties of the alginate films remarkably, e.g. addition of 15% of NFC increased a tensile strength of the film from 70.02 to 97.97MPa. After ionic cross-linking, the tensile strength of the film containing 10% of DCC was increased from 69.63 to 125.31MPa. The biocomposite films showed excellent grease barrier properties and reduced water vapour permeability (WVP) after the addition of cellulose fibres, except when unmodified birch pulp was used.

Extrusion processing of green biocomposites: Compounding, fibrillation efficiency, and fiber dispersion

ABSTRACTThe efficiency of twin‐screw extrusion process to fibrillate cellulose fibers into micro/nanosize in the same step as the compounding of green bionanocomposites of thermoplastic starch (TPS) with 10 wt % fibers was examined. The effect of the processing setup on micro/nanofibrillation and fiber dispersion/distribution in starch was studied using two types of cellulose fibers: bleached wood fibers and TEMPO‐oxidized cellulose fibers. A composite with cellulose nanofibers was prepared to examine the nanofiber distribution and dispersion in the starch and to compare the properties with the composites containing cellulose fibers. Optical microscopy, scanning electron microscopy, and UV/Vis spectroscopy showed that fibers were not nanofibrillated in the extrusion, but good dispersion and distribution of fibers in the starch matrix was obtained. The addition of cellulose fibers enhanced the mechanical properties of the TPS. Moisture uptake study revealed that the material containing TEMPO‐oxidized fibers had higher moisture absorption than the other composites. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 39981.

Mechanical properties and foaming behavior of injection molded cellulose fiber reinforced polypropylene composite foams

This paper investigates the effects of cellulose content and processing conditions on the mechanical properties and foaming behavior of injection molded cellulose fiber reinforced polypropylene composite foams. Composite foams were injection molded using an advanced structural foam molding machine with N2 as a physical blowing agent. Foamed specimens were prepared at different injection speeds and void fractions. The mechanical properties and foam morphologies of the specimens were evaluated. The results suggested that the specific flexural modulus was increased and the specific flexural strength and Izod impact strength were maintained by foaming, and that the strength, modulus, and notched Izod impact strength increased with the increase of cellulose content. Additionally, the results suggested that the cell morphology of the composite foams was improved by the increase of void fraction and the addition of cellulose fiber.

Influence of the simultaneous addition of bentonite and cellulose fibers on the mechanical and barrier properties of starch composite-films

The addition of nanoclay or cellulose fibers has been presented in the literature as a suitable alternative for reinforcing starch films. The aim of the present work was to evaluate the effect of the simultaneous incorporation of nanoclay (bentonite) and cellulose fibers on the mechanical and water barrier properties of the resultant composite-films. Films were prepared by casting with 3% in weight of cassava starch, using glycerol as plasticizer (0.30 g per g of starch), cellulose fibers at a concentration of 0.30 g of fibers per g of starch and nanoclay (0.05 g clay per g starch and 0.10 g clay per g starch). The addition of cellulose fibers and nanoclay increased the tensile strength of the films 8.5 times and the Young modulus 24 times but reduced the elongation capacity 14 times. The water barrier properties of the composite-films to which bentonite and cellulose fibers were added were approximately 60% inferior to those of starch films. Diffractograms showed that the nanoclay was intercalated in the polymeric matrix. These results indicate that the simultaneous addition of bentonite and cellulose fibers is a suitable alternative to increase the tensile strength of the films and decrease their water vapor permeabilities.

Preparation and characterization of PVA composites with cellulose nanofibers obtained by ultrasonication

Cellulose nanofibers were obtained from microcrystalline cellulose (MCC) by the action of hydrodynamic forces associated with ultrasound. Nanofibers isolated from MCC by applying different ultrasonication conditions were characterized to elucidate their morpho-structural features by field emission scanning electron microscopy, atomic force microscopy, X-ray diffraction, and dynamic light scattering. Several differences were observed regarding the size of the nanofibers obtained in different ultrasonic conditions, but no significant changes in the crystalline structure of cellulose nanofibers were detected. The obtained cellulose fibers were used at low levels (1 to 5 wt.%) as reinforcements in a poly(vinyl alcohol) (PVA) matrix. The mechanical and thermal properties of the PVA/cellulose fibers nanocomposites films were determined. The tensile strength and modulus of the PVA film were significantly improved by the addition of cellulose nanofibers. Slightly higher onset degradation temperatures were obtained for PVA composites in comparison to neat PVA, showing an increase of the thermal stability caused by the addition of cellulose fibers.

Evaluation of Castor Oil Polyurethane Reinforced with Lignin and Cellulose from Sugarcane Straw

The search for materials from renewable sources such as vegetable oil-based polymers, polyurethane based on castor oil represents a promising alternative in researches. Using castor oil polyurethane as matrix for composites reinforced with lignin and cellulose from sugarcane straw is in tune with economical and environmental interests. The objective of this work was the evaluation of the changes on the structure and thermal behavior of castor oil polyurethane composites reinforced with lignin and cellulose from sugarcane straw. The cellulose and lignin were extracted from the straw by acid hydrolysis and then they were milled. For the production of the polyurethane, the mass reason between polyol (castor oil) and diisocyanate was 1.5:1.0. Reinforcement of the matrix was done changing the concentration of cellulose and lignin. SEM micrographs of fractured surfaces of the obtained composites and thermal analysis (TGA) were done. No lignin could be seen in SEM micrographs, what suggests a blend material behavior. The addition of cellulose fibers (30%) and lignin (40%) to the polyurethane matrix has caused an increase of the stiffness in the resulting composite when compared with the pure matrix. Above these rates, stiffness decreases. The presence of lignin or cellulose fibers in polyurethane matrix seems to increase mechanical properties of the composite, and also introduce better thermal stability than the pure matrix. Its presence might also bring other significant synergetic properties to the final composite, what has currently been studied. At the same time, the blend behavior of Polyurethane-Lignin composites has been investigated.

Effect of cellulose fibers on the crystallinity and mechanical properties of starch-based films at different relative humidity values

The objective of this study was to investigate the effect of the addition of cellulose fibers on the mechanical and physicochemical properties of starch-based films plasticized with glycerol. Film samples were prepared from solutions with 3% of cassava starch, with the addition of 0, 0.10, 0.30 and 0.50 g of fibers/g of starch. The mechanical properties of samples conditioned at different relative humidity (RH) values were determined through tensile and stress relaxation tests. SEM micrographs of the films showed a homogeneous and random distribution of the cellulose fibers, without pores or cracks. Films with fibers were more crystalline and had higher tensile strength and rigidity, but lower elongation capacity. On the other hand, addition of cellulose fibers increased the stability of starch-based films subjected to RH variations, solving a classical problem encountered with this kind of film. Thus, the addition of cellulose fibers to starch-based films is an effective way to prepare stronger and more stable films.

Cast-in-Place Cellulose Fiber-Reinforced Cement Paste, Mortar, and Concrete

Fiber-reinforced concrete is a fast-growing technology. This research considers the use of cellulose fibers as an inexpensive alternative to synthetic fibers. This study characterizes the behavior of cellulose fiber-reinforced paste, mortar, and concrete and investigates rheological, dispersion, and mechanical properties of the materials. The addition of cellulose fibers to a cementitious material stiffens the matrix. This stiffening limits the maximum usable fiber volume. At fiber volumes used, fibers offer little improvement in flexural properties. Optical and scanning electron microscopy are used to inspect fiber dispersion. A technique is developed to locate fibers in hardened specimens. Correlations among fiber dispersion, mechanical performance, and rheology are investigated. Restrained ring shrinkage tests are performed on paste and mortar. Fibers are found to reduce the width of shrinkage cracks in both materials. Fiber dispersion, matrix rheology, and mechanical performance cannot be correlated. Fibers disperse well under normal mixing conditions, regardless of matrix rheological properties.

Thermal and thermomechanical properties of biocomposites made from modified recycled cellulose and recycled polypropylene

AbstractResidual cellulose fibers from the paper industry have been used as reinforcements in recycled polypropylene (PP) composites. The main obstacle to obtaining good properties with this biocomposite is deficiencies in the compatibility between the nonpolar matrices and the polar cellulose fibers used as reinforcements. The aim of this work was to improve the compatibilization between these cellulose fibers and the PP matrix with four different methods: modification by the addition of polypropylene–maleic anhydride copolymer (PPgMA) during the process of blending, preblending modification of the cellulose with a solution of PPgMA, modification of cellulose by silanes (vinyltrimethoxysilane), and acetylation of cellulose. Blends with all of the differently modified celluloses were prepared with the cellulose content varied up to 40%, and then all of the blends were subjected to thermal (differential scanning calorimetry and thermogravimetric analysis) and thermomechanical (dynamic mechanical thermal analysis) analyses. The results showed that the addition of cellulose fibers improved the thermomechanical behavior of the PP, increasing the value of the log of the dynamic modulus, and affected the thermal and thermooxidative behavior. Moreover, an advantage of the use of a recycled PP containing a small quantity of ethyl vinyl acetate (EVA) as a prime material in the composition was the enhancement of mechanical properties. The use of these methods for the modification of cellulose led to more desirable thermal and thermooxidative stabilities. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2353–2360, 2003

Elemental and intravenous total parenteral nutrition diet-induced gut barrier failure is intestinal site specific and can be prevented by feeding nonfermentable fiber.

Parenteral nutrition and elemental diets both cause bacterial translocation, immune dysfunction, and increased infection in laboratory animals, whereas elemental diets, with or without fiber, ameliorate some, but not all gut barrier failure. The purpose of this study is to investigate, in an Ussing chamber system, whether elemental vs. parenteral diets induce gut barrier failure in specific anatomical sites in the intestine and whether fiber can ameliorate this phenomenon. Controlled study in laboratory animals. University laboratory. Male Sprague-Dawley rats. Nutritional support was provided to rats for 7 days by oral total parenteral nutrition (TPN; elemental diet) 307 kcal/kg/day, intravenous TPN (parenteral diet) 307 kcal/kg/day via jugular venous catheters, or rodent chow (controls). Permeability to bacteria in intestinal segments of ileum, jejunum, and colon was evaluated in an Ussing chamber. Results were correlated with bacterial translocation to the mesenteric lymph nodes. Intravenous TPN caused greater bacterial translocation in all small intestinal segments and the cecum when compared with chow (p <.05). Oral TPN caused gut barrier failure only in the ileal segment, but not in the remainder of the small intestine (p <.001). Addition of cellulose provided a greater protection of the ileum to permeability than did pectin (p <.01). TPN causes global intestinal barrier failure, but elemental diet prevents barrier failure in parts of the small intestine other than the ileum. The addition of cellulose fiber to elemental diet can ameliorate further barrier failure in the ileum.

Effect of diet on blood lead concentration in the cynomolgus monkey

Infant cynomolgus monkeys ( Macaca fascicularis) were reared from birth in an infant primate nursery and dosed with lead acetate (2 mg Pb/kg body wt/day) from approximately 100 days of age. The monkeys were switched from an infant formula diet to a diet of primate chow and water at 460 days of age. Beginning at approximately 935 days of age, various diets were fed in the following order: infant formula plus a restricted amount of primate chow, infant formula only, infant formula plus cellulose fiber, infant formula plus phytic acid, cow's milk, and primate chow plus water. Blood lead content was determined throughout the experiment. At 360 days of treatment (approx. 460 days of age) the blood lead concentration was 90 μg/dl but decreased to 50 μg/dl within 30 days after the diet was changed to primate chow and water. When the monkeys were 935 days of age the introduction of the infant formula plus a restricted amount of primate chow had little effect on blood lead concentrations. However, when primate chow was removed from the diet so that the monkeys were fed infant formula only, there was a rapid increase in blood lead from approximately 40 to 220 μg/dl. The addition of cellulose fiber to the infant formula had no effect on blood lead concentrations, whereas the addition of phytic acid caused an abrupt decrease to approximately 85 μg/dl. Blood lead concentrations increased to approximately 190 μg/dl when cow's milk only was fed and decreased to approximately 55 μg/dl when the monkeys were returned to a diet of primate chow and water. In a second experiment, infant monkeys were reared as above and dosed from birth with lead acetate at a rate of 25 μg Pb/kg body wt/day. The monkeys were switched to a primate chow and water diet at 200 days of age and at approximately 900 days of age various dietary changes were made that were similar to those described above. Although blood lead concentrations were much lower and more viable than in the 2-mg/kg/day dose group, the data showed a pattern similar to those of the higher dose group.

Network flocculation and fractionation of latex particles by means of a polyethyleneoxide—phenolformaldehyde resin complex

Flocculation of monodisperse latex particles by the sequential addition of a phenolformaldehyde resin and polyethyleneoxide has been investigated. It is suggested that flocculation takes place via a mechanical enmeshment mechanism in a transient hydrogen-bonded network formed by complexation of the two flocculating components. No flocculation takes place unless the latex dispersion is sensitized by the addition of cellulose fibers (collector). It is suggested that the role of the collector is to sweep the transient network and the therein entrapped particles before the network breaks apart (syneresis). Latex removal was found to be independent of latex concentration, but strongly dependent on latex particle size. Larger particles are more easily removed, thus establishing the network character of the complex formed. Experiments with latex particles of different sizes revealed the apparent mesh-size distribution of the transient network. It has also been demonstrated that the network can be used to fractionate mixtures of latex particles according to their size. A theoretical framework from which these network flocculation and fractionation phenomena may be understood is proposed.