Query: acetylation flax fibers

title: Comparison of Various Chemical Treatments Efficiency in Relation to the Properties of Flax, Hemp Fibers and Cotton trichomes
abstract: The main aim of this study was to chemically modify the plant fiber surface. Hemp, flax fibers and cotton trichomes were subject of surface treatments using silanization, acetylation, benzoylation, and mercerization processes. The fiber properties were evaluated with the use of fourier transform infrared spectroscopy (FTIR) scanning electron microscopy (SEM) wide angle X ray analysis (WAXS) and thermogravimetric analysis (TGA) Additionally, humidity and color of the modified fibers were evaluated. Chemical treatment of the plant fibers reduced their hydrophilic nature, increased the moisture resistance, and improved their thermal stability. In all the cases the silanization process proved to be the most effective method of improving fiber thermal stability and moisture resistance, yet mercerization and benzoylation methods offered satisfying results as well.

title: Solvent free acetylation of lignocellulosic fibers at room temperature: Effect on fiber structure and surface properties
abstract: Acetylation is one of the most interesting chemical treatments to improve the affinity of lignocellulosic fibers with polymeric matrices for the elaboration of several types of composites. In this paper, the acetylation of flax and wood pulp (bleached softwood Kraft pulp and thermomechanical pulp) fibers was carried out at room temperature in a solvent free system with acetic anhydride in the presence of sulfuric acid as catalyst. The effect of acetylation on the fine structure of fibers was investigated by spectroscopic methods, while the extent of acetylation was quantified by weight percent gain. The effect of reaction time on fiber morphology was studied at macro and microscale using scanning electron microscopy, optical microscopy, and fiber quality analysis. The evolution of the hydrophobic/hydrophilic character of fibers was determined by contact angle measurements. The wettability of fibers by liquid epoxy resin was also evaluated to confirm the improvement of the affinity of acetylated fibers with the epoxy matrix. It was found that the hydrophilic character of fibers decrease with increasing reaction time, whereas the trend was less pronounced beyond specific reaction times. Acetylated fibers can therefore be potential candidates for replacing nonbiodegradable reinforcing materials in composite applications.

title: Oil spill cleanup by raw flax fiber: Modification effect, sorption isotherm, kinetics and thermodynamics
abstract: Modification of raw flax fiber by acetylating process and microwave energy was useful in the application of oil spill cleanup. The change in fibers was characterized by scientific analysis(FTIR, SEM, XRD and contact angle) The results indicate that the modified fibers by the acetylating process have extra hydrophobic properties than both microwave radiation and raw fibers. Oil/Artificial seawater(3.5% salinity by NaCl) system (O/W S) was used as a liquid phase operation system. Fast oil sorption was reached at 6 min and attained(equilibrium) at 10 min. Acetylated fiber(ACF)has higher oil sorption capacity(24.54 g/g) than both raw(13.75 g/g) and microwave fiber(17.42 g/g) with exothermic effect. The sorption kinetics and isotherms indicate that the oil sorption onto ACF agreement with pseudo second order kinetic model and Freundlich isotherm model. Also, the economic reusing of fiber was evaluated. The process of acetylation demonstrated the ability to improve the absorptive properties of the fibers, which makes them able to compete with synthetic fibers in the oil spill cleanup and industrial applications, as well as cheap and eco friendly due to their biodegradation.

title: Effect of Hygrothermal Aging and Surface Treatment on the Dynamic Mechanical Behavior of Flax Fiber Reinforced Composites
abstract: The recent developments of FRP (fiber reinforced polymer) are towards the growth and usage of natural FRP in the field of engineering due to both environmental and economic benefits. Flax fiber is one of the most commonly used natural fibers. One of the critical factors affecting the mechanical behavior of FFRP (flax fiber reinforced polymer) is hygrothermal aging. Some experimental works have been conducted to investigate the effect of hydrothermal aging on static behavior of FFRP. However, fewer efforts have been made to study its damping properties after hydrothermal aging. In this paper, the effect of surface treatment (including alkalization, silanization, acetylation and alkali silanization) on dynamic mechanical behavior of FFRP under hygrothermal aging is studied. The results show that water resistance and damping properties of FFRP are improved after surface treatment. The acetylation treated FFRP exhibits excellent damping performance among all treated specimens.

title: Biodegradation of chemically modified flax fibers in soil and in vitro with selected bacteria.
abstract: The extent and rate of degradation of flax (Linum usitatissimum) fibers, both in the native state and after surface chemical modification (acetylation or poly(ethylene glycol) PEG, grafting) was investigated under laboratory conditions in two different biodegrading environments. Degradation of the fibers under aerobic conditions by the action of the microorganisms present in soil is assessed with the ASTM 5988 96 method by monitoring carbon dioxide evolution. In vitro biodegradation experiments were carried out by exposing the fibers to a pure culture of Cellvibrio fibrovorans bacteria and measuring the mass loss as a function of time. Despite the complexity of the system, the results of degradation in soil were satisfactorily reproducible, although the absolute rates were found to change in different experiments using the same soil. The degradation rate of acetylated fibers in soil nearly equals that of unmodified fibers, whereas in the pure culture, acetylated fibers biodegrade slower than native fibers. The opposite happens with the PEG grafted fibers, which degrade slower than unmodified flax in soil and at a comparable rate upon in vitro exposure to the bacterial culture. The different biodegradation kinetics observed in the two biodegrading environments were attributed to differences of biocenoses, abiotic factors, and biodegradation assessing methods. Nevertheless, the final extent of biodegradation was the same for modified and unmodified fibers both in soil and in the pure culture, showing that the surface chemical modifications applied do not significantly affect biodegradability of the flax fibers.

title: Natural cellulose fibers: heterogeneous acetylation kinetics and biodegradation behavior.
abstract: Steam exploded fibers from flax (Linum usitatissimum) are heterogeneously acetylated using acetic anhydride and sulfuric acid as catalyst, with the aim to modify the surface properties without changing fiber structure and morphology. The acetylation reaction follows first order kinetics up to a reaction time that depends on catalyst concentration (15 h when using 0.4 vol of H(2)SO(4) or 50 h with 0.1 vol The fibers undergo no structural and/or morphological changes under either reaction condition. On the contrary, surface damage and structural modifications appear after longer reaction times, when the reaction kinetics change. The extent of biodegradation of acetylated fibers, evaluated from the weight percent remaining after 13 days of exposure to previously isolated cellulolytic bacteria Cellvibrio sp. decreases with increasing acetylation degree. After biodegradation the fibers show a higher acetyl content than before the experiment, indicating that the bacteria preferentially biodegrade unsubstituted cellulose, though also acetylated chains are cleaved. Biodegradable acetylated cellulose fibers with modified surface chemistry and unchanged structure are obtained for applications as polymer composite reinforcements.

title: Bio composite of bacterial poly(3 hydroxybutyrate co 3 hydroxyhexanoate) reinforced with vegetable fibers
abstract: Composites of a bacterial copolyester poly(3 hydroxybutyrate co 3 hydroxyhexanoate) P(3HB co 3HH) with flax fibers were investigated. A satisfactory reinforcing effect was observed in composites prepared by compression molding and using long fiber mats (long fiber composites, LFC) On the other hand, composites obtained by batch mixing fibers with molten polymer resulted in poor mechanical properties, owing to drastic fiber shortening during processing (short fiber composites, SFC) In order to improve fiber matrix adhesion in SFC, fibers chemically modified at the surface (by acetylation or by short chain PEG grafting) were also used. The best results were obtained with surface acetylated fibers. In the flax fiber composites the crystallization rate of P(3HB co 3HH) remarkably increased compared with that of the plain polyester. The fibers displayed a nucleating effect on P(3HB co 3HH) crystallization, whose magnitude depended on fiber surface chemistry. This feature was confirmed by the appearance of transcrystallinity in isothermal crystallisation experiments run in a hot stage of a polarized optical microscope.

title: Durability of natural/synthetic/biomass fiber based polymeric composites: Laboratory and field tests
abstract: The desire for environmental sustainability, coupled with the need to lower production costs, has encouraged the composite industry to utilize natural fibers. These fibers are a readily available resource with a relatively low price. Biocomposites (BCs) are produced by mixing polymeric materials with natural resin and then adding natural fibers for reinforcement. These natural fibers (biofibers) can include wood (hardwood and softwood) or nonwood fibers (wheat, kenaf, hemp, jute, sisal, and flax, bamboo, palm wood) Biofibers can reduce cost and weight, while improving physical properties of the BC, but one significant problem with these materials is susceptibility to biodegradation. Understanding the processes of degradation and their effects on properties can be useful for developing improved materials. At the same time, it will also be important to develop more durable biofibers for inclusion in these composites. Processes such as acetylation, furfurylation, or thermal modification may be useful for enhancing BC properties but will require much more research before they become practical in these applications. This chapter reviews composites made from biopolymers such as polylactic acid, polyhydroxybutyrate, cellulose acetate, and polyhydroxyalkanoates and their resistance to biological degradation.

title: Development of biodegradable composites with treated and compatibilized lignocellulosic fibers
abstract: The aliphatic polyester Bionolle 3020 was combined with lignocellulosic fibers, namely, flax, hemp, and wood, to produce biodegradable composite materials. The effect of two fiber surface treatments, acetylation and propionylation, and the addition of maleic anhydride (MA) grafted Bionolle 3001 as a compatibilizer on the fiber/matrix interfacial adhesion was studied. The compatibilizer was synthesized through a MA grafting reaction in the presence of dicumyl peroxide as an initiator. The composites' mechanical properties, water absorption, fracture morphology (scanning electron microscopy) and biodegradation were evaluated. Both the fiber treatments and the compatibilizer incorporation significantly improved the composites' tensile strength, whereas an important reduction in the water absorption was found with the addition of treated fibers. Moreover, fiber incorporation into the matrix increased its biodegradation rate.

title: THE POTENTIAL OF DIFFERENT PULPING PROCESSES IN PRODUCTION OF PULP PLASTIC COMPOSITES (PPC) FROM BAGASSE AND RICE STRAW
abstract: Natural fibres are renewable, biodegradable, low cost, low density raw materials with high stiffness and strength compared to the other conventional products such as glass, aramid and carbon. There are a large variety of natural fibers such as rice straw, rice husk, wheat straw, corn stalks, palm, bagasse, hemp, flax and other agricultural residues. Natural fibers contain various organic materials (mainly celluloses as well as hemicelluloses and lignin) and there are several chemical treatments such as bleaching, esterification, silane treatment, use of compatibilizer, acetylation, alkali treatment and treatment with other chemicals in order to enhance the fiber matrix adhesion, which improve the physical and mechanical properties of composites. This study investigates different pulping processes as a novel chemical treatment on bagasse and rice straw fibers and consequently, properties of biocomposites. By pulping processes, the treated natural fibers as a biofiller could be used to produce the new classes of bio composites defined as pulp plastic composites (PPCs) Different pulping processes which are categorized in mechanical, semi chemical and chemical methods led to natural fibers with different anatomical and chemical properties such as surface modification and delignification in comparison with untreated fibers. Furthermore, the comparison of natural fibers treated by chemical and mechanical pulping processes and effects of these treatments on physical and mechanical properties of natural fibers are worth considering. Therefore in this paper, High density polyethylene (HDPE) bagasse and rice straw fibers treated by four pulping processes (AS AQ (alkaline sulfite anthraquinone) SODA AQ (soda anthraquinone) MEA (monoethanolamine) and chemical mechanical pulping (CMP) and maleic anhydride polyethylene as coupling agent were used to produce pulp plastic composites (PPCs) by injection molding. The physical and mechanical properties of corresponding composites were evaluated according to ASTM standards. The results showed that compared to untreated bagasse and rice straw/HDPE composite, the addition of bagasse and rice straw pulp fibers increased significantly the mechanical properties such as tensile strength and modulus, flexural strength and modulus, and hardness. The chemical pulps reinforced composites showed better mechanical strengths than that of CMP reinforced composites, but in some properties, CMP pulp composites have comparable results to the chemical pulp reinforced composites. Natural fibers (untreated and treated) increased water absorption and thickness swelling of composites compared to pure HDPE. The comparison of PPCs from bagasse and rice straw untreated and treated fibers will be also presented and discussed.