Fillers In Polymer Matrices Research Articles

MODIFICATION OF BUCKWHEAT HUSK POWDER AND CREATION OF COMPOSITE MATERIAL ON ITS BASIS

Abstract Waste of plant origin is becoming increasingly relevant for use as fillers in polymer matrices to create new composite materials. In this study, a composite material based on biodegradable thermoplastic polylactide (PLA) and buckwheat husks (BHS) was prepared. L-PLA IngeoTM Biopolymer 4043D in pellet form (Nature Works LLC, USA) was chosen as the base for the polymer matrix. BHS in the form of fine powder (harvested in 2023) was used as a plant filler. In order to purify the raw material from dust and pathogenic bacteria, as well as to increase the adhesion ability of the material, BHS was treated with 4% alkaline solution (NaOH). Modification of the filler was carried out using organosilicon resin K-9 (manufacturer Khimprodukt LLC, Lyubertsy, Russia). The filler was added to the material in the ratio of 22 %, 32%, 42% by weight of the product. A technology for modification of BHS powder is proposed, which makes it possible to significantly increase the wetting angle from 59.47±1.59° to 95.6±1.35°. The strength properties and water absorption resistance of the developed composites with different weight ratios of PLA/ BHS are investigated. The modification of the filler changes the structure and properties of BHS, as well as contributes to the improvement of strength properties. At the ratio PLA 68 wt.% / modified BHS 32 wt.% the composite material has the following characteristics: density - 1342 kg/m3, bending strength – 21.31 MPa, maximum deformation value – 0.22 mm, Vickers hardness at a load of 200 g – 20.21, water absorption – 1.9%. Research on the utilization of plant components will make it possible to integrate into industry innovative products based on renewable and biodegradable resources that will meet all societal needs and contribute to the preservation of the environment and exhaustible resources.

Biochar/Biopolymer Composites for Potential In Situ Groundwater Remediation.

This study explores the use of pine wood biochar (BC) waste gasified at 950 °C as fillers in polymer matrices to create BC@biopolymer composites with perspectives in groundwater remediation. Four biochar samples underwent different sieving and grinding processes and were extensively characterized via UV-Vis, FTIR, and FESEM-EDS, highlighting the fact that that BCs are essentially graphitic in nature with a sponge-like morphology. The grinding process influences the particle size, reducing the specific surface area by about 30% (evaluated by BET). The adsorption performances of raw BC were validated via an adsorption isotherm using trichloroethylene (TCE) as a model contaminant. A selected BC sample was used to produce hydrophilic, stable polymer composites with chitosan (CS), alginate (ALG), potato starch (PST), and sodium carboxymethylcellulose (CMC) via a simple blending approach. Pilot sedimentation tests over 7 days in water identified BC@PST and BC@CMC as the most stable suspensions due to a combination of both hydrogen bonds and physical entrapment, as studied by FTIR. BC@CMC showed optimal distribution and retention properties without clogging in breakthrough tests. The study concludes that biopolymer-based biochar composites with improved stability in aqueous environments hold significant promise for addressing various groundwater pollution challenges.

Synthesis of stable fluorescent ethylene-vinyl acetate copolymers based on in-situ grafted rare-earth organic complexes and antioxidants through transesterification

The synthesis and application of rare earth organic complexes (REOCs) are gaining attention due to their advantages including low excitation thresholds and high luminescence efficiencies. However, their integration as functional fillers in polymer matrices is constrained by challenges related to poor dispersion and limited stability. This study introduces a novel method for synthesizing stable fluorescent polymers by co-grafting europium (Eu) complexes and the antioxidant 3,9-bis-{1,1-dimethyl-2[β-(3-tert-butyl-4-hydroxy-5-methylphenyl-)propionyloxy]ethyl}-2,4,8,10-tetraoxaspiro[5.5]-undecane (AO-80) onto an ethylene-vinyl acetate (EVA) matrix through an in-situ synchronous grafting strategy, aiming to address these dual challenges of poor dispersion and rapid aging. In this study, Eu complexes characterized by low excitation thresholds and high hexahydrate (EuCl3) and selected ligands - 1,10-phenanthroline (Phen), alpha-thienyl trifluoroacetone (HTTA), and 4-acetoxybenzoic acid (4-ABA). Through transesterifications, the Eu complexes were successfully grafted onto the EVA chain, achieving a uniform dispersion within the EVA matrix to form fluorescent polymers. Furthermore, the incorporation of antioxidant AO-80 as a radical scavenger can significantly mitigate fluorescence attenuation. Through detailed exploration of transesterifications under various conditions, optimal grafting rates of 11.34% for EVA with Eu complexes and 22.87% for EVA with AO-80 were achieved. The synthesized fluorescent polymers of EVA synchronously grafted with Eu complexes and AO-80 have been proven to obtain markedly improved fluorescence stability and aging resistance by outdoor aging tests. Our findings not only validate the in-situ reaction grafting method as an efficient strategy for producing polymer composites with excellent fluorescence stability but also pave the way for future research aimed at overcoming the limitations of REOCs in photovoltaic and agricultural applications.

Investigation of Mechanical and Thermal Stabilities of Tamarind Seed- and Peanut Shell Powder-Reinforced Vinyl Ester Composite

Efficient exploitation of agricultural waste results in a more sustainable and ecofriendly environment since it lessens the burden of their disposal, which has become increasingly important in recent times. Due to their high mechanical strength and high thermal stability, these biodegradable low-value agrosolid wastes have the potential to successfully replace synthetic fibers and fillers in polymer matrices in the form of reinforcements. This work deals with the addition of low-cost and renewable hybrid natural fillers, tamarind seed filler (TMS), and peanut shell powder (PNS) as particulate reinforcements to the vinyl ester (VE) resin. Traditional compression molding creates TMS/PNS-VE hybrid composites with filler loadings ranging from 5% to 30%. After the composites were fabricated, they were tested for strength properties and heat deflection temperature. A detailed experimental analysis of the mechanical properties was conducted. According to the findings, 20 wt.% hybrid filler loading to the vinyl ester polymer exhibited peak tensile, flexural, and impact strengths of 40.3 MPa, 142 MPa, and 16 kJ/m2, respectively, which is 1.52, 1.69, and 1.29 times the properties of the virgin polymer. However, the peak elongation at break 3.9% was obtained at 30 wt.%. Similarly, the heat deflection temperature (HDT) test of TMS/PNS-VE composites showed a maximum rise of 50.91% at 25 wt.% of filler loading. This is 1.51 times greater than the heat deflection temperature of the pure vinyl ester resin. The findings made it quite clear that adding 20 wt.% biosolid waste hybrid particulate fillers made out of tamarind seed and peanut shell to vinyl ester is the optimum weight, which improves the mechanical and thermal properties of the TMS/PNS-VE composite, making it suitable for making cost-effective materials for lightweight applications. This study also utilizes scanning electron microscopy (SEM) to investigate the microstructural characteristics of the composites, correlating these features with their mechanical performance.

Reinforced energy storage performance of poly(vinylidene fluoride) composite films by filling with surface fluorinated one-dimensional barium titanate nanofibers

One-dimensional barium titanate nanofibers/poly(vinylidene fluoride) (PVDF) composite films were prepared by casting technology. To improve the dispersion of nanofibers in the PVDF matrix and enhance the interface bonding between nanofibers and the PVDF matrix, surface modification of nanofibers was obtained by fluorination treatment. Experimental and theoretical simulation studies were conducted to investigate the effects of surface fluorination-modified one-dimensional barium titanate nanofibers on the micro morphology, structure, dielectric constant, and energy storage density of PVDF composite films. The results showed that the barium titanate powder synthesized by electrospinning had a good one-dimensional fiber morphology, with a diameter of 70–130 nm and a length of 4–15 µm. The surface fluorination treatment was able to significantly improve the dispersion and bonding of the one-dimensional barium titanate nanofiber in the PVDF matrix. As the filling volume of the one-dimensional nanofibers increased, the dielectric constant of the PVDF composite film significantly increased. When the filling volume of the surface fluorinated one-dimensional barium titanate nanofiber was 7.5 vol%, the room temperature dielectric constant of the PVDF composite film reached 21.8, and the surface fluorinated one-dimensional barium titanate nanofiber/PVDF composite film exhibited lower dielectric loss and high breakdown strength. When the filling volume of the surface fluorinated one-dimensional barium titanate nanofiber was 2.5 vol%, the energy storage density of the PVDF composite film was 7.9 J/cm3, which was 2.82 times that of pure PVDF. The improvement of energy storage performance can be attributed to the good dispersion of the surface fluorinated barium titanate nanofibers in the PVDF matrix and the good interface situation. Finite element simulation further revealed that the surface fluorinated one-dimensional nanofibers could effectively improve the breakdown strength of the composites. That provides a promising way to enhance the dispersion and interface bonding of filler in polymer matrices, thereby achieving high-performance composites with high dielectric constant, high breakdown strength, and excellent energy storage density.

Conductive Plastics from Al Platelets in a PBT-PET Polyester Blend Having Co-Continuous Morphology.

Conductive plastics are made by placing conductive fillers in polymer matrices. It is known that a conductive filler in a binary polymer blend with a co-continuous morphology is more effective than in a single polymer, because it aids the formation of a ‘segregated conductive network’. We embedded a relatively low-cost conductive filler, aluminium nano platelets, in a 60/40 PBT/PET polymer blend. While 25 vol.% of the Al nanoplatelets when placed in a single polymer (PET) gave a material with the resistivity of an insulator (1014 Ωcm), the same Al nano platelets in the 60/40 PBT/PET blend reduced the resistivity to 7.2 × 107 Ωcm, which is in the category of an electrostatic charge dissipation material. While PET tends to give amorphous articles, the 60/40 PBT/PET blends crystallised in the time scale of the injection moulding and hence the conductive articles had dimensional stability above the Tg of PET.

Reactive Jetting of High Viscosity Nanocomposites for Dielectric Elastomer Actuation

AbstractThe layer‐by‐layer nature of additive manufacturing is well matched to the layer construction of stacked dielectric actuators, with inkjet printing offering a unique opportunity due to its droplet‐on‐demand capability, suitable for multi‐material processing at high resolution. This paper demonstrates the use of high viscosity, multi‐material jetting to deposit two‐part reactive inks with functionalized nanofillers to digitally manufacture dielectric elastomers for soft robots with high precision, and shape manipulation. Graphene‐based fillers, including graphene oxide (GO) and thermally reduced graphene oxides (TRGOs), have been incorporated into a polydimethylsiloxane (PDMS) matrix at low loading (below the percolation threshold). Consequently, the dielectric constant of the elastomer dramatically increases (by 97%) compared to neat PDMS, yielding a more than 20‐fold increase in the electric‐field induced electromechanical contraction (from 0.3 to 6.7%). This study shows that the oxygen‐functionalities present in GO and TRGOs, which possess a moderate conductivity, improve the dispersion of those fillers in polymer matrices, thus significantly improving the dielectric constant of the polymer composites. Inkjet printing of high‐performance, soft electroactive composites enables high‐speed, reliable fabrication of monolithic artificial muscles (leading to stronger, cheaper, and more capable soft robotic devices) and provides a vital stepping stone towards fully additively manufactured soft robots.

Boosted dielectric performance of organic–inorganic nanocomposites based on BaTiO3 via 2D TiO2 templates

Organic–inorganic hybrid dielectrics composed of nanoscale ceramic fillers in polymer matrices have attracted considerable attention because they can overcome the inherent limitations such as the low dielectric constant, high dielectric loss, and low film density associated with mechanically flexible pristine polymer materials. Barium titanate (BaTiO3), a representative perovskite-based material with a high permittivity, is suitable for applications as nanofillers in nanocomposite dielectrics. X-ray diffraction combined with Raman analysis suggest that a two-step hydrothermal synthesis, which uses synthesized TiO2 nanosheets as a template, is an effective method for the synthesis of pure BaTiO3 nanoparticles compared with other methods. Ultrasonic treatment is employed to disperse BaTiO3 nanoparticles with different concentrations in polyvinyl alcohol (PVA) polymer, and the dielectric performance of the nanocomposite films has been examined. In this study, 20 wt% BaTiO3–PVA nanocomposite dielectric showed superior capacitance and dielectric constant performance, i.e. five times higher than that of the pristine PVA.

Spent Coffee Grounds as Property Enhancing Filler in a Wholly Bio‐Based Epoxy Resin

AbstractCoffee is one of the most popular beverages in the world but generates copious amounts of waste that is usually discarded. This discarded waste, the so‐called spent coffee grounds (SCGs), can become a valuable resource if compelling use cases are found. Following a circular economy approach, one such use case can be employing SCGs as filler in polymer matrices, complementing conventional inorganic fillers such as kaolin clay. This work studies the effect of SCGs as filler in wholly natural thermosets, investigating changes in curing kinetics and final material properties. Different SCG content, for example, 25 to 35 wt% and various curing time and temperature is employed. SCGs are found to have a moderate catalytic effect on the curing reaction. Furthermore, SCGs are found to heavily increase stiffness of the final material, especially when oils present in SCGs are previously extracted, raising the rubber plateau modulus from around 5 MPa to 14 MPa. Extracted SCGs are most efficient during curing at room temperature, where they significantly improved the tensile strength, toughness, and hardness of the filled material compared to the pristine resin.

Characteristics of Palm Kernel Shell and Palm Kernel Shell-Polymer Composites: A Review

The peculiar characteristics of Palm Kernel Shell (PKS) may have corresponding effects on polymer mono composites and hybrid composites when used as filler in polymer matrices. This review paper relates Palm Kernel Shell (PKS), palm kernel shell-mono composites, and palm kernel shell hybrid composites in terms of identification, sampling, and analysis. The purpose was to establish the properties of palm kernel shells and their composites as documented by various researchers in a one-stop-shop document for use by current and future researchers. The accidental and judgmental sampling procedures were employed to sample documents that relate palm kernel shells and polymers. The study revealed that lignocellulos palm kernel shell properties, including lignin, cellulose, and hemicellulose might vary depending on the geographic location of the plant from which the shell is derived. Similarly, the mineral content of PKS, such as carbon, iron, Aluminum, potassium, silicon, phosphorus, oxygen, and cesium, among others, were found to vary. Other properties identified include solid density, porosity, specific gravity, specific heat capacity, moisture content, and angle of repose. The paper also observed that using PKS as a filler material in polymer composites could modify the properties of the filler and hence PKS/polymer composites. The paper concludes that PKS may be a good filler material when used in the development of PKS/oil palm mesocarp/polyethylene hybrid composites. Chemical treatment of the PKS particles may further enhance the characteristics of the evolved hybrid composite material.

Facile one−step preparation of acetylated cellulose nanocrystals and their reinforcing function in cellulose acetate film with improved interfacial compatibility

A facile one− step method to fabricate acetylated cellulose nanocrystals (ACNCs) was developed by using mixed sulfuric acid and acetic acid hydrolysis. It could be demonstrated that the esterification of surface hydroxyl groups took place simultaneously with hydrolysis of amorphous regions of cellulose, which was confirmed by transmission electron microscopy (TEM), Fourier transform infrared spectra (FT − IR) and X − ray diffraction (XRD) measurement. The as − prepared ACNCs exhibited typical rod − like morphology with diameter and length of 12 − 18 and 191 − 234 nm, respectively. All − cellulose nanocomposite films were subsequently produced by introducing ACNCs into cellulose acetate (CA) matrix through solution casting technique. The mechanical performance of nanocomposites was significantly enhanced due to the uniform dispersion of ACNCs and favorable CA − ACNC interface. The results showed that the tensile strength, Young’s modulus and elongation at break of nanocomposite film were increased by 78%, 58% and 68%, respectively, with the introduction of 5% ACNCs. Moreover, the nanocomposite films could retain good optical transparency. These results indicated ACNCs have a great potential to be used as reinforcing filler in polymer matrices for extending their industrial applications.

Thermal, morphological and mechanical properties of composites based on polyamide 6 with cellulose, silica and their hybrids from rice husk

The use of cellulosic fibers from different natural sources as fillers in polymer matrices to improve their properties has been extensively studied in the last years. It is mainly due to the vast availability of natural fibers as well as their biodegradability. The purpose of this present work was to extract cellulose, silica, and cellulose-silica fillers – these last called “hybrids” – from rice husk through delignification and subsequent oxidation and, then, prepare composites with polyamide 6 and improve mainly its thermal-mechanical properties. The content of 10 wt.% of fillers was inserted in PA 6 matrix. Infrared spectroscopy pointed the main characteristic peaks of cellulose and silica of hybrids, as thermogravimetric analysis showed high thermal stability of fillers, allowing their incorporation in PA-6 matrix by extrusion method. Thermo dynamic-mechanical analysis showed, in a general overview, a significant improvement of mechanical properties of composites, as elastic modulus, compared with neat polyamide-6, mainly the one with 2.5 wt% of silica and 7.5% of cellulose. This last also showed increasing of degree of crystallinity, measured by differential scanning calorimetry, showing the extraction efficiency of fillers from rice husk as well as the potential application of composites as structural components in automotive parts.

Bioinspired Polydopamine Coating as an Adhesion Enhancer Between Paraffin Microcapsules and an Epoxy Matrix.

Microencapsulated phase change materials (PCMs) are attracting increasing attention as functional fillers in polymer matrices, to produce smart thermoregulating composites for applications in thermal energy storage (TES) and thermal management. In a polymer composite, the filler–matrix interfacial adhesion plays a fundamental role in the thermomechanical properties. Hence, this work aims to modify the surface of commercial PCM microcapsules through the formation of a layer of polydopamine (PDA), a bioinspired polymer that is emerging as a powerful tool to functionalize chemically inert surfaces due to its versatility and great adhesive potential in many different materials. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) evidenced that after PDA coating, the surface roughness increased from 9 to 86 nm, which is beneficial, as it allows a further increase in the interfacial interaction by mechanical interlocking. Spectroscopic techniques allowed investigating the surface chemistry and identifying reactive functional groups of the PDA layer and highlighted that, unlike the uncoated microcapsules, the PDA layer is able to react with oxirane groups, thereby forming a covalent bond with the epoxy matrix. Hot-stage optical microscopy and differential scanning calorimetry (DSC) highlighted that the PDA modification does not hinder the melting/crystallization process of the paraffinic core. Finally, SEM micrographs of the cryofracture surface of epoxy composites containing neat or PDA-modified microcapsules clearly evidenced improved adhesion between the capsule shell and the epoxy matrix. These results showed that PDA is a suitable coating material with considerable potential for increasing the interfacial adhesion between an epoxy matrix and polymer microcapsules with low surface reactivity. This is remarkably important not only for this specific application but also for other classes of composite materials. Future studies will investigate how the deposition parameters affect the morphology, roughness, and thickness of the PDA layer and how the layer properties influence the capsule–matrix adhesion.

Effect of filler loading and size on the mechanical and morphological behaviour of natural fibre-reinforced polystyrene composites

ABSTRACT Due to ever increasing use of polymer composites and rising environmental concerns throughout the world, greater attention is being paid to the incorporation of lingo-cellulosic materials as filler in polymer matrices instead of synthetic materials in the field of aerospace and automobile industry. In this work, polystyrene composites using wheat husk, rice husk and mustard husk as fillers are synthesised using in-situ polymerisation technique. Three different filler loading (5, 10 and 15 %) and three different filler sizes (250–355 µ, 355–500 µ, 500–710 µ) were utilised for the studying the effect of these compositions on different mechanical properties of the synthesised composites. The results have shown that the filler size 250–355 µ and 5% loading give the maximum values for tensile strength, flexural strength and hardness for all the three types of fillers. While in case of water absorptivity the lower the size/loading, lesser would be the water absorbed. The SEM analysis is done to study the fractured surface of the specimen.

Nanocomposite egg shell powder with in situ generated silver nanoparticles using inherent collagen as reducing agent

Silver nanoparticles (AgNPs) were in situ generated in poultry hen egg shell powder (ESP) by one step thermal assisted method using the inherently present collagen as a reducing agent. The nanocomposite egg shell powder (NCESP) with in situ generated silver nanoparticles was characterized by scanning electron microscopy (SEM), Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), thermogravimetric analysis (TGA) and antibacterial tests. The prepared NCESP had the spherical AgNPs in the size range of 50–120 nm with most of them from 81 nm to 90 nm. Further, the average size of the AgNPs generated in the NCESP was 88 nm. The X-ray analysis indicated the presence of both AgNPs and AgO nanoparticles (AgONPs) in the NCESP. The possible mechanism of generation of AgNPs and AgONPs in the NCESP was also proposed. The thermal stability of the NCESP was found to be higher than that of the ESP. The NCESP exhibited excellent antibacterial activity against both the Gram negative and positive bacteria. The NCESP made from poultry waste ESP can be utilized as a low-cost antibacterial cleaning powder for house ware and also as low-cost antibacterial filler in polymer matrices to make antibacterial hybrid nanocomposites.

Detailed experimental and theoretical investigation of the thermomechanical properties of epoxy composites containing paraffin microcapsules for thermal management

AbstractMicroencapsulated phase change materials (PCMs) are being increasingly employed as functional fillers in polymer matrices for thermal management. Therefore, the effect of PCM microcapsules on the rheological, microstructural, thermal and mechanical properties of the host polymer matrices must be understood. This work concerned the preparation of epoxy polymers filled with PCM microcapsules (MC) in various concentrations and their subsequent characterization. The MC phase increases the viscosity of epoxy before curing, thereby reducing castability and hindering elimination of air bubbles. The latter was reflected in an increase in porosity for highly filled compositions, as elucidated by density measurements and microscopic investigation. SEM micrographs showed that the adhesion between the capsule shell and the epoxy matrix was not optimal. The interfacial weakness and the intrinsic low stiffness and strength of MC caused a reduction in mechanical properties, as evidenced by the Nicolais‐Narkis and Pukanszky models. On the other hand, at zero or low deformation levels, the interface presents no gaps and is able to transfer load and heat, as demonstrated by the data of elastic modulus, modeled with the Halpin‐Tsai and Lewis‐Nielsen models, and those of thermal conductivity, in excellent agreement with the Pal model. POLYM. ENG. SCI., 2020. © 2020 Society of Plastics Engineers

A combination of graphene and graphene nanoplatelets: An effective way to improve thermal conductivity for polymers

Graphene has emerged as an efficient filler in polymer matrices due to its unique properties. What is not entirely clear, however, is how to transfer the unique attributes exhibited at the nanoscale to the macroscale. The primary focus of this study was on understanding the main causes that lead to the improvement of thermal conductivity for polymers with a hybrid reinforcement material consisting of graphene and graphene nanoplatelets. The thermal properties of epoxy matrix composites filled with the hybrid reinforcement material were studied experimentally in order to provide an effective way to improve thermal conductivity for polymers. Comparisons with other existing reinforcement materials were made in terms of thermal properties. A mathematical model was developed to evaluate the effectiveness of the hybrid reinforcement material in improving thermal conductivity. The results indicated that a twenty-fold increase in thermal conductivity can be achieved for epoxy resins when the content of the hybrid reinforcement material is 8% by weight. The main cause is that the hybrid reinforcement material can significantly reduce interfacial thermal resistance. The hybrid reinforcement material is quite effective compared to other existing reinforcement materials. The thermal performance of the resultant composite materials has no significant degradation at high temperatures.

The alignment of AlN platelets in polymer matrix and its anisotropic thermal properties

The thermal conductivity of polymer composites can be enhanced by the vertical alignment of anisotropic aluminum nitride (AlN) platelet fillers in polymer matrices. The AlN platelets in polymer matrix were aligned in the direction of in-plane and out-of-plane by using the doctor blading and the lamination process. The alignment of AlN plates in the out-of-plane or the in-plane direction has been confirmed by XRD and FE-SEM investigations. The polymer composite with the out-of-plane aligned AlN platelets showed almost 1.5 times or 2 times higher thermal conductivity than those with the AlN spheres or the in-plane aligned AlN platelets at the same filler content, respectively. This result could be attributed to the improvement of thermal pathway generated along the plane of platelets and the decrease of interfaces between the filler and the polymer.

Modification of natural fibers from Thespesia lampas plant by in situ generation of silver nanoparticles in single-step hydrothermal method

Ligno-cellulosic fibers have a great market and propose higher value addition and options to develop various products but they do not have inherent antimicrobial properties. In this study, a simple hydrothermal method was applied to build up antimicrobial properties to natural fibers by in situ-generating silver nanoparticles (AgNPs) in them. Herein, the ligno-cellulosic Thespesia lampas natural fibers were selected to develop antimicrobial activity using silver nitrate (AgNO3) solution by hydrothermal method. The modified fibers were characterized by SEM, FTIR, XRD, TGA, and antibacterial activity tests. The modified fibers had spherical AgNPs with an average size of 95 nm. The thermal stability of the modified fibers was higher than that of the unmodified fibers. The modified fibers exhibited good antibacterial activity against both the Gram negative and Gram positive bacteria. These modified fibers can be considered as fillers in polymer matrices to make antibacterial composites.

Environmentally-Friendly Extraction of Cellulose Nanofibers from Steam-Explosion Pretreated Sugar Beet Pulp.

Cellulose nanofibers (CNFs) with an average diameter of 22 nm were prepared from sugar beet pulp (SBP) via an environmentally-friendly method. Steam-explosion pretreated SBP was treated with hydrogen peroxide (H2O2) bleaching, high-speed blending, and ultrasonic treatment. Thermogravimetric analysis showed that hemicellulose was partially hydrolyzed in the steam-cooking stage, pectin was removed in the explosion stage, and lignin was removed by H2O2 bleaching. The removal of non-cellulosic components was confirmed by Fourier-transform infrared (FT-IR) spectroscopy. Morphological analysis showed that steam-explosion pretreatment largely extracted the binder materials of hemicellulose and pectin. This exposed the microfibrillated cellulosic fibers, which promoted subsequent nanofibrillation. X-ray diffraction showed that the CNFs had a crystallinity index of 62.3%. The CNFs had good thermal stability, and thus have potential for use as fillers in polymer matrices. The only chemical reagent used in this green method was H2O2. Combining H2O2 bleaching with steam explosion, high-speed blending, and ultrasonic treatment reduced the overall energy consumption and increased the efficiency of the CNFs extraction. The method, therefore, has potential application in industrial processes.