Mechanical Pulp Fibres Research Articles

Cellulose nanofibrils as a bio-based binder for wood fiber composite insulation panels with enhanced thermo-mechanical properties for structural wall sheathing applications

A low-density wood fiber insulation panel (WIP) composite was developed with 100 % petrochemical-free, bio-based binder with high mechanical strength, water resistance and thermal insulation properties. This study investigated the manufacturing process of composite WIPs made with mechanical pulp fibers with cellulose nanofibrils (CNFs), lignin-containing CNFs (LCNFs), hybridized CNFs-LCNFs, and CNFs-starch as a binder on different scales and evaluated the effects of binder type and content on the panels’ physical, mechanical, and thermal properties. All panels had excellent thermal resistivity values, which increased with the decrease in density. The WIPs made with LCNFs as binder had lower mechanical properties, but it was possible to replace 20 % CNFs with LCNFs to obtain the same performance as neat CNFs as the binder. Untreated panels had poor water resistance but the water absorption properties were significantly improved with the addition wax. The WIPs made with 5 % and 7.5 % binder content and 2 % wax addition could fulfill the criteria of regular and structural wall sheathing applications, respectively. Overall, the results confirm the potential of CNFs and LCNFs to be used as 100 % bio-based adhesives to produce eco-friendly composite WIPs with excellent thermo-mechanical properties to be used for regular and structural wall sheathing applications.

Acoustic optimization of a flow through sonicator for fibrillation of cellulose fibers

Fibrillation is identified as the most energy intensive process step in pulp and paper manufacturing and improved energy efficiency is the motivation for development of alternative technologies. The aim of this study is to explore the potential of a new refining concept based on cavitation, focusing on the optimization of acoustic cavitation efficiency of the proposed flow-through sonicator concept. The simulations utilize the linearized wave equation in the frequency domain with an addition of nonlinear attenuation introduced by cavitation bubbles. Verification is made by pressure measurements, calorimetry, and foil tests. The fibrillation capability was validated on chemi-thermo mechanical pulp fibers at low consistencies. Fiber properties was characterized by ultrasonic spectroscopy, fiber analysis and SEM. The objective is to optimize the energy transfer efficiency from electrical input power to acoustic cavitation intensity for efficient fibrillation of cellulose fibers. Results showed changes in fiber dimensions and fiber morphology, however, improvements in tensile strength index, measured and predicted by ultrasonic spectroscopy, was limited to 20 % at an energy level of 804 kWh/bdt. To enhance energy efficiency and paper strength properties, it is suggested to add a hydrodynamic cavitation device prior to the sonicator to initiate cavitation bubbles and to increase turbulence intensity.

Improving the flexibility of bamboo mechanical pulp fibers for production of high soft tissue handsheets

Softness is generally seen as one of the most important consumer attributes that can determine the quality of tissue papers. Herein, a green integrated technology, i.e., ultrasonication combined with subsequent cellulase treatment, was developed to improve the flexibility of bamboo CTMP fibers and the softness of obtained handsheets fabricated with treated bamboo CTMP. Ultrasonication can effectively open up the fiber structure by destroying its crystalline structure and expose the fiber surface, which can greatly facilitate the efficiency of cellulase treatment for improved fiber flexibility. It was found that the crystallinity of bamboo pulp decreased from 56.7%–36.2% after ultrasonication (800 W, 40 min) and cellulase (0.3 EGU/g) treatments. Single bamboo fiber flexibility was increased from 2.5 × 2.5 × 1014/N·m2 to 26 × 1014/N·m2 after ultrasonication pretreatment (50 min). The softness and other physical properties of prepared tissue handsheets were also enhanced compared with that of the control and a commercial tissue sample.

N-Doped Carbon Aerogels Obtained from APMP Fiber Aerogels Saturated with Rhodamine Dye and Their Application as Supercapacitor Electrodes

We developed an efficient and environmentally friendly strategy for synthesizing an N-doped carbon aerogel by the carbonization of an alkaline peroxide mechanical pulp (APMP) fiber aerogel saturated with rhodamine B (RB) dyes. The APMP aerogel was prepared via cellulose extraction, sol-gel, and freeze drying. The resulting aerogel had a high adsorption capacity (250 mg g−1) and a fast adsorption rate (within 30 s) towards RB dyes. The saturated aerogel was used as a starting material for further carbonization to prepare N-doped carbon aerogels. SEM studies showed that the 3D network structure of the APMP aerogels was well preserved after RB adsorption and carbonization. The prepared carbon aerogel exhibited a graphitized structure, and N (2.15%) was doped at pyridinic N and pyrrolic N sites in the 3D carbon network. The specific capacitance of the N-doped carbon aerogel reached 185 F g−1 at a current density of 1 A g−1, which is higher than carbon aerogels (155 F g−1).

Improving fire retardancy of cellulosic thermal insulating materials by coating with bio-based fire retardants

Abstract Sustainable thermal insulating materials produced from cellulosic fibers provide a viable alternative to plastic insulation foams. Industrially available, abundant, and inexpensive mechanical pulp fiber and recycled textile fiber provide potential raw materials to produce thermal insulating materials. To improve the fire retardancy of low-density thermal insulating materials produced from recycled cotton denim and mechanical pulp fibers, bio-based fire retardants, such as sulfonated kraft lignin, kraft lignin, and nanoclays, were coated onto sustainable insulating material surfaces to enhance their fire retardancy. Microfibrillated cellulose was used as a bio-based binder in the coating formula to disperse and bond the fire-retardant particles to the underlying thermal insulating materials. The flammability of the coated thermal insulating materials was tested using a single-flame source test and cone calorimetry. The results showed that sulfonated kraft lignin-coated cellulosic thermal insulating materials had a better fire retardancy compared with that for kraft lignin with a coating weight of 0.8 kg/m2. Nanoclay-coated samples had the best fire retardancy and did not ignite under a heat flux of 25 kW/m2, as shown by cone calorimetry and single-flame source tests, respectively. These cost-efficient and bio-based fire retardants have broad applications for improving fire retardancy of sustainable thermal insulating materials.

Surface Characterization of Plasma-treated Eucalyptus Alkaline Peroxide Mechanical Pulp using Electronic Spectroscopy Chemical Analysis and Atomic Force Microscopy

Eucalyptus alkaline peroxide mechanical pulp (APMP) fibers were modified by a low-temperature plasma (LTP) treatment within an air and oxygen mixture. An atomic force microscope (AFM) and electronic spectroscopy chemical analysis (ESCA) were used to analyze the morphological and chemical information of eucalyptus APMP fibers. According to the AFM results, LTP treatment etched the fibers’ surface, allowing for the removal of hydrophobic substances from the surface. According to the ESCA, the oxygen to carbon ratio of the APMP fiber surface increased from 50.08% to 55.47%, and the C1 peak area decreased from 8.89% to 8.45% after a LTP treatment. All of these results indicate that a LTP treatment can modify the APMP fibers and reduce the contents of lignin and extractives, thus exposing more carbohydrate.

Physical strength improvement of Eucalyptus alkaline hydrogen peroxide mechanical pulp by low-temperature plasma treatment

Low-temperature plasma treatment technology is an efficient and environmentally friendly surface treatment technology that has been extensively studied for the surface chemical modification to pulp fibers. In this study, Eucalyptus alkaline peroxide mechanical pulp (APMP) fibers were modified using a low-temperature plasma generator. The tensile index of the fibers after low-temperature plasma treatment under different conditions was measured and analyzed to evaluate the relationship between the plasma treatment conditions and the physical strength improvement of APMP. It was revealed that factors such as gas source (oxygen, argon, and nitrogen gases), discharge power, vacuum level, and modification time affected the physical strength properties of APMP. In addition, the change in carboxyl group content in the pulp fibers after low-temperature plasma treatment was measured using the Headspace Gas Chromatography (HS-GC) method. The carboxyl content in the fiber increased remarkedly after low-temperature plasma treatment, which was beneficial for improving the physical strength properties of paper made from the APMP.

Application of Pulp Fiber for Automotive Brake Lining

Mechanical and/or chemical pulp fiber is usually used for papermaking and other kind of paper products. In fact, physical properties of chemical and/or mechanical pulp showed that it can be utilized as filler of automotive brake lining. Mechanical pulp is non-asbestos cellulosic fiber with high heat absorption rate which can fit into criterion of good quality brake lining. Pulp fiber was defiberation mixed with some other composite materials can create high fiber bonding with some hardness, friction materials, clutching, heat and dust retainer fiber which is free of asbestos fiber. Current automotive brake lining uses asbestos fiber as main filler, which is in fact known as cancer triggers. A series of study and assessment in using pulp fiber in a specified composition as brake lining filler have been carried out. The research and field experiment revealed that a mixture of pulp fiber can be further examined and feasible for brake lining prototype filler application which is ready for automotive vehicles operation. The development and application fiber brake lining filler has been tested on two wheeled vehicles with considerable result.

N-methylol acrylamide grafting bamboo fibers and their composites

The present study focuses on the modification of four commercial bamboo fibers (BFs), namely bamboo particles (PF), mechanical pulp fibers (MP), chemical pulp fibers (CP) and original bamboo fibers (OF), with a water-soluble monomer, N-methylol acrylamide (NMA), in the presence of sulfuric acid as a catalyst, surface chemistry of the grafted BFs with NMA, and their reinforcing effects on unsaturated polyester (UPE) in terms of the interface and bonding mechanisms, and hence mechanical properties of the resulting BF-UPE composites. Fourier transform infrared spectroscopy (FTIR) analysis showed that the reaction degree of BFs with NMA followed CP > MP > PF > OF due to their different fiber morphology and chemical compositions. This was further confirmed by X-ray photoelectron spectroscopy (XPS) with the increase in N content and the reduction in O/C ratio on the fiber surfaces. NMA treated BF gave rise to an improved interfacial adhesion between the treated fibers and UPE resins, and hence mechanical properties of BF-UPE composites, although the magnitudes are dependent on the combined effect of NMA grafting efficiency and fiber characteristics (i.e. types) of BFs.

Adsorption of cationized eucalyptus heteropolysaccharides onto chemical and mechanical pulp fibers

Adsorption of native eucalyptus heteropolysaccharides onto bleached softwood and hardwood kraft pulps and bleached CTMP was explored in this work to potentially improve the mechanical properties of the final furnish. It was found that adsorption of native heteropolysaccharides onto softwood kraft pulp was slightly higher than hardwood; however, heteropolysaccharides with low arabinose content were preferentially adsorbed onto the hardwood fibers. Adsorption onto CTMP was the lowest, although the general phenomenon of native absorption was rather low under the applied conditions. A strategy to increase the absorption required cationizing the heteropolysaccharides with 2,3-epoxy propyltrimethylamonium chloride that in general significantly increased the overall phenomenon, again with the same general tendencies as observed for the native adsorption.

Comparison of Interfiber Bonding Ability of Different Poplar P-RC Alkaline Peroxide Mechanical Pulp (APMP) Fiber Fractions

In recent years, the alkaline peroxide mechanical pulping performed with refiner-chemical preconditioning (P-RC APMP) has obtained a wide application in many paper grades in China. This is due to such desirable pulp characteristics as its high bulk, opacity, and light scattering coefficient. However, compared with its bleached chemical pulps, the poplar P-RC APMP has weak bonding strength, which limits its application in value-added products. Usually, the interfiber bonding abilities of different fiber fractions are quite different. In this study, the page bonding strength index (B) and the interfiber bonding abilities (shear bond strength per unit area (b) and relative bonding area (RBA)) of different P-RC APMP fiber fractions were extrapolated by the traditional Page Equation. The results show that the higher B could be obtained when the fiber fraction was shorter or smaller. The same trend was observed for b and RBA. Wet pressing was used to improve the bonding ability, and higher pressure of wet pressing or shorter fiber fraction can lead to obviously higher tensile strength.

Preparation and Properties of Multi-Layer Composite Paperboard

In order to study the preparation and property of the multi layer composite paperboard, bleached wheat straw pulp, bleached chemical thermal mechanical pulp and waste newsprint pulp are used as raw materials to making paperboard. The results show that the bonding force between fibers of grasses chemical pulp is strong which can improve the bonding strength between the layers. Bleached wheat straw pulp is used as outer layer and waste news paper pulp is used as inner layer to make composite paperboard has high physical properties. Bleached chemical thermal mechanical pulp fiber is shorter, so paperboard tightness and physical strength reduce, which can be used as the lining of the multi layer composite paperboard to improve the stiffness of the paperboard and reduce the cost.

Defibration mechanisms of autohydrolyzed Eucalyptus wood chips

The objective of this study was to evaluate the influence of autohydrolysis on mechanical defibration of Eucalyptus wood chips. The autohydrolysis process changed notably the mechanical properties of Eucalyptus chips. The removal of mainly hemicelluloses undoubtedly decreased the overall pulp yield. Hemicellulose losses cannot be solely accounted for the changes in the wood and pulp properties, because the autohydrolysis also caused changes in lignin. When comparing the mechanical pulp fibers of the original wood chips with the fibers resulting from the autohydrolyzed wood material, it was clear that the rupture point shifted from the secondary wall to the middle lamella, confirmed by X-ray photoelectron spectroscopy measurements. This study revealed the mechanical behavior of autohydrolyzed wood chips and can provide useful information for integration of mechanical pulp mills into the biorefinery concept in the future.

Topochemical activation of pulp fibres

A new concept for topochemical activation of mechanical pulp fibres was investigated. The activation concept was based on attachment of precursors of peracids onto the surface of the fibres prior to hydrogen peroxide bleaching. The activators used in this work were: tetraacetylethylenediamine (water soluble), lactose octaacetate (LOA, colloidal particles, and low water solubility) and sucrose octaacetate (partially soluble in water). LOA showed promising results for application in the surface activation concept due to attachment of colloidal particles on the outmost surface of the fibres, simultaneously contributing to a brightness increase. Surface coverage by lignin on fibres had decreased after the bleaching process with activators, which was detected by X-ray photoelectron spectroscopy and time-of-flight secondary ion mass spectrometry.

Characteristics of Poplar Preconditioning Followed by Refining Chemical Treatment Alkaline Peroxide Mechanical Pulp Fiber Fractions and Their Effects on Formation and Properties of High-Yield Pulp Containing Paper

High-yield pulp (HYP) has various fractions, and they not only play an important role in the papermaking process but also affect paper properties. Hence, it is necessary to clarify the impact of different HYP fractions on paper formation and properties. In this study, the characteristics of poplar preconditioning followed by refining chemical treatment alkaline peroxide mechanical pulp fractions were determined, and their effects on paper formation and paper properties were investigated. The results show that the HYP fiber is not as flexible as the bleached wheat straw pulp fiber. Compared with the HYP long-fiber fraction, the short-fiber fraction can improve the formation index more favorably. It was also found that the long-fiber fraction can maintain the strength properties, while having a negligible effect on the light-scattering coefficient; on the contrary, the short-fiber fraction can improve the light-scattering coefficient effectively but reduces the strength properties.

Hybrid clay functionalized biofibres for composite applications

Micro-injection moulded composites of softwood fibres from two different pulping processes in thermoplastic polypropylene matrix have been studied. Surface modification of hydrogen peroxide bleached thermo mechanical pulp fibres (BTMP) from spruce (Picea abies L.) and chemical sulphate pulp fibres (BKraft) from pine (Pinus sylvestris L.) was achieved by co-precipitation of layered double hydroxide (LDH) particles that were further functionalized with sodium dodecyl sulphate (SDS) surfactant in conditions similar to wet end in paper production. Micro-injection moulded test specimens were subjected to uniaxial tension tests, water absorption, micromechanical deformation and microscopic studies. Optical micrographs show that functional pulp was homogeneously dispersed into polypropylene matrix where as the untreated fibres agglomerated during moulding. When composites were prepared with BTMP fibres the electrostatically bound SDS on fibre surface increased elongation at break by 70%. LDH particles intensified dissipation of shear energy to BKraft fibres degrading the average fibre length by 50% during moulding. Functionalization with SDS surfactant, however, increased average fibre length up to 125% in comparison to LDH modification.

ACOUSTIC PROPERTIES OF POLYPROPYLENE COMPOSITES REINFORCED WITH STONE GROUNDWOOD

Currently, acoustic isolation is one of the problems raised with building construction in Spain. The publication of the Basic Document for the protection against noise of the Technical Building Code has increased the demand of comfort for citizens. This has created the need to seek new composite materials that meet the new required acoustical building codes. In this paper we report the results of the newly developed composites that are able to improve the acoustic isolation of airborne noise. These composites were prepared from polypropylene (PP) reinforced with mechanical pulp fibers from softwood (Pinus radiata). Mechanical and acoustical properties of the composites from mechanical pulp (MP) and polypropylene (PP) have been investigated and compared to fiberglass (FG) composites. MP composites had lower tensile properties compared with FG composites, although these properties can be improved by incorporation of a coupling agent. The results of acoustical properties of MP composites were reported and compared with the conventional composites based on fiberglass and gypsum plasterboards. Finally, we suggest the application of MP composites as a light-weight building material to reduce acoustic transmitions.

Hydrophobisation of mechanical pulp fibres with sodium dodecyl sulphate functionalised layered double hydroxide particles

Abstract Hydrogen peroxide bleached spruce (Picea abies L.) made of thermo mechanical pulp (BTMP) fibres were modified with layered double hydroxides (LDH). The LDH particles were precipitated onto the BTMP fibre surfaces from aqueous solutions of urea and NaOH. The modified BTMP was further functionalised with sodium dodecyl sulphate (SDS) surfactant to produce pulp with hydrophobic character. The contact angle measurement with water on paper showed that the functionalisation with SDS was successful. The apparent contact angles varied in between the initial θ= 75° of the reference pulp up to θ= 135° of the SDS functionalised pulp. A hydrophobic surface was obtained already with 2.0% weight to weight ratio of SDS in pulp suspension. A high affinity between the LDH particles and the BTMP fibres was found as well. The investigated fibre modification route offers a new feasible tool in fibre surface treatment.

Effects of Enzymatic Modification of Masson Pine Mechanical Pulp on Fiber Morphology and Pulp Properties

Mechanical pulping is a kind of high yield pulping that comes with the comprehensive utilization of plant material. Mechanical pulp has lots of benefits, such as simple process, low pollution, good bulkiness, fine stiffness, excellent optical performance and good printability. However, it also has disadvantages of lower paper physical strength and higher refining energy. In this paper, AU-MTPE90 enzyme and acid xylanase were used to modify the masson pine mechanical pulp before refining. The effects of modification on the shape parameters of masson pine mechanical pulp fiber and pulp properties were studied. The results showed that after modified by AU-MTPE90 enzyme and acid xylanase，the drainability of the refined pulp increased, the average fiber length increased and the fines percent decreased. The curl index and kink index increased slightly after modified by AU-MTPE90 enzyme，while the kink index decreased after modified by xylanase.

The middle lamella remainders on the surface of various mechanical pulp fibres

The surface of various mechanical pulp fibres including thermomechanical pulp (TMP), chemithermomechanical pulp (CTMP), and alkaline peroxide mechanical pulp (APMP) fibres, were characterized using SEM, AFM, and XPS. With SEM and AFM, middle lamella material was observed to be non-fibrillar, patch-like, while fibre secondary wall was observed to have a microfibrillar structure. It was found that after the first-stage refiner, lignin-rich middle lamella remainders are present on the fibre surface of all three pulps, although most of the fibre surfaces expose microfibrillar structure. After the final-stage refining, large amounts of granules are present on the TMP fibre surface. In contrast, most middle lamella remainders remain on the surface of CTMP fibres after final stage refining and even after peroxide bleaching. XPS results have confirmed that the non-fibrillar surface material is the lignin-rich middle lamella remainder., and the remainders of middle lamella contribute to the high surface lignin concentration.