Wood Pulp Fibers Research Articles

Deteriorating dispersibility of flushable wet wipes during storage: Role of fibre swelling and ionic shielding

Wet wipes are everyday products with the purpose to be flushed down the toilet after usage and dispersed into single fibres and small fragments thereby. During wet storage, these wipes can deteriorate their dispersibility over time, characterized by the slosh box disintegration test, recently named dispersibility ageing. This effect in flushable wet wipes, usually made of long man-made cellulose fibres and short wood pulp fibres, can be reduced by using unbleached softwood kraft pulp as the short fibre component. The aim of this work is to analyse mechanisms that could contribute to dispersibility ageing. Therefore, we will discuss three mechanisms that are able to explain this effect, that occurs in cellulosic fabrics when stored in water. Swelling (1) is demonstrated to be a long-term effect, but altering swelling with pH and salt addition has no effect on dispersibility ageing, making it unlikely that swelling contributes to it. With ionic shielding (2) a mechanism has been introduced that could impact dispersibility ageing by cations leaching from the wood pulp, which was demonstrated for an unbleached softwood kraft pulp by conductivity measurements over wet storage time. These cations neutralize the negatively charged pulp fibre fibrils and restrict their possibility to entangle with each other, which could contribute to decreasing dispersibility ageing. We will discuss the mechanism of interdiffusion (3) in dispersibility ageing, although we were not able to find a method that quantifies the contribution of cellulosic polymer diffusion to the time-dependent deterioration in dispersibility.

Preparation and Physical Properties Evaluation of glass/wood Pulp Fibers wet-laid Felts

ABSTRACT Mechanical properties of pure glass fiber wet-laid felts with no adhesives are relatively poor and limit the using. The aim of this study is to analyze the hybrid effects of glass/wood pulp wet-laid felt (GWFF) via papermaking technology. The influence of wood pulp fiber weight ratios on the physical properties of GWFFs is studied. The results show that GWFFs can obtain excellent uniformity when wood pulp fiber weight ratios are less than 50%. GWFFs with 20% wood pulp fiber weight ratios exhibit optimum break elongation, flexural property, and bursting strength. It also finds that tensile strength and Young’s modulus increase with wood pulp fiber weight ratios due to the effect of surface roughness of fibers and hydrogen bonds between fibers.

Development and performance evaluation of wood-pulp/glass fibre hybrid composites as core materials for vacuum insulation panels

Thermal insulation is regarded as one of the key technologies to combat ever-increasing energy consumption. An efficient method to develop innovative and cost-effective core materials for vacuum insulation panels (VIPs) is proposed. The materials are natural and sustainable wood pulp fibre doped with various amounts of glass fibre as a reinforcing phase to create a hybrid multi-level network composite core material through the conventional wet papermaking process. The basic characteristics of both wood pulp fibre and glass fibre are studied, and the effect of glass fibre on the textural properties and thermal insulation performance of the composite core materials of the VIPs is investigated. The results showed that all core materials achieved an uniform dispersion of fibres, and the axes of the fibres were randomly in the three-dimensional (3D) network structure. Upon increasing the glass fibre content, the thermal conductivity of the VIPs gradually decreased due to structural changes in the core materials. Both the pore diameter and porosity increased with the glass fibre content. The thermal insulation of the developed VIP was comparable to those of most commercial VIP products. Thermal conductivities of 6.48 and 4.69 mW/(m∙K) were obtained for the VIP with 100% wood pulp fibre and wood-pulp/glass fibre composites (50% mass ratio), respectively. Furthermore, after 365 days of storage, the composite core material with 50% glass fibre maintained a thermal conductivity of 7.42 mW/(m·K) without a getter or desiccant. Even in the accelerated aging condition after 28 days, the increase in the thermal conductivity was less than 5.00 mW/(m·K).

Polymeric coacervate coating for flame retardant paper

Cellulosic paper (from wood fibers) is a highly flammable material that is used in corrugated carboard, packaging, printing, and construction. While there is significant work focused on depositing a flame retardant coating onto the individual wood pulp fibers, there are very few studies that apply flame retardant coatings to already-cast paper. In an effort to improve the flame retardant properties of paper, a polymer-dense coacervate composed of polyethylenimine (PEI) and poly(sodium phosphate) (PSP) was deposited in a single step and subsequently crosslinked with glutaraldehyde. In a vertical flame test, the crosslinked PEI/PSP coacervate-coated paper achieves self-extinguishing behavior, and an average char length of 3.4 in, with only a 35% weight gain. Additionally, the crosslinked coating retains its flame retardant properties after water immersion and conditioning tests. This coacervate system is the first polymeric coating to be successfully deposited onto commercially available cellulosic paper for the purpose of flame retardancy.

Evaluation of fiber compositions, strength indicators, and disintegration patterns of flushable sanitary products in relevance to what is flushable

ABSTRACT Sanitary products (SPs) such as toilet paper and moist wipes are marketed as flushable products (FPs). SP manufacturers, wastewater authorities, and governmental agencies describe FPs in their own terms, and cause confusion about what is safe to flush with respect to sewer operations. To identify sewer-safe FPs, 11 toilet paper (TP) and 39 flushable wipe (FW) samples that were collected from around the world were examined to assess critical links between their fiber compositions, strength indicators, and disintegration performance. The findings illustrate that products that are made of primarily wood-pulp fibers have low strength, disintegrate rapidly, and are safe flushables. In contrast, products that contain strong and synthetic fibers (e.g. polyester) exhibit high strength, disintegrate slowly, and pose significant risk of accumulation in sewer systems. Suggestions are offered for product improvement and for long-term sustainability of FPs and wastewater infrastructures.

Processing pulp fiber into high strength composites

ABSTRACT The mechanical performance of wood fibre-based panels is unsatisfactory for many advanced engineering structures and applications; it also releases free formaldehyde. Here, we report a simple and effective strategy to transform wood fiber (pulp fiber) into high strength composite panels without adhesive bonding. Our two-step process involves layer by layer self-assembly of bleached cellulose mixed with microcrystalline cellulose (MCC) and dibasic calcium phosphate (DCP). This was followed by hot-pressing, leading to the complete densification of the wood pulp fiber with highly aligned cellulose nanofibers. The result showed that the flexural and tensile strength could reach up to 147MPa and 58 MPa, respectively, which are much stronger than those of existing types of wood fiberboard, mainly resulting from the synergistic effects of hydrogen bonding and ionic bonding between the pulp fibers and DCP sheets.

Single fiber swelling behavior for natural and man-made cellulose fibers under alkaline treatment

Swelling behavior of cotton, dissolving wood pulp (DWP), viscose staple fiber, and Tencel staple fiber in varying sodium hydroxide (NaOH) concentration were investigated by means of optical microscopy and were characterized by molecular mass distribution, X-ray diffractometer, and dynamic vapor sorption. The effect of temperature (20–45 °C) and duration (0–120 min) was studied. The results reveal that the swelling ratio of fiber in alkali solution depends on fiber accessibility and NaOH concentration. Viscose staple fiber exhibited the highest swelling ratio and lowest swelling ratio observed for dissolving wood pulp fiber among all the materials. The cotton or DWP fibers provide maximum swelling during alkaline steeping (18wt % lye) at higher temperatures, i.e., 45 °C. As for viscose staple fiber and Tencel staple fiber, using 12 wt% lye concentration and steeping at lower temperatures, i.e., 20 °C maximum swelling behavior.

Optimization of Technological Parameters of Straw Fiber-Based Plant Fiber Seedling Pot Raw Materials

Straw fiber seedling pots are a promising substitute for plastic seedling pots. The mixing mode of straw fiber affects the mechanical properties of the raw material membrane of the seedling pot. To explore the processing technology of making the raw material membrane of the seedling pot with two kinds of plant fibers in a layered manner, the optimal combination of the process parameters of the raw material membrane of the seedling pot without additives in the production process was studied experimentally. Response surface methodology (RSM) was used to analyze the parameters (beating degree of unbleached softwood kraft pulp fiber, beating degree of wheat straw fiber, wheat straw fiber quality percentage content, and film grammage) with regard to the dry tensile index and Z-direction tensile index of the seedling pot body. The optimal process parameter combination with a certain dry tensile index and Z-direction tensile index of seedling pot raw material was obtained by using four factors and five levels of a quadratic regression orthogonal rotation center combination design parameter optimization experiment. The optimal technical parameters were optimized as wheat straw fiber quality percentage content 70%, film grammage 70 g/m2, unbleached softwood kraft pulp fiber beating degree 47–48 °SR, and wheat straw fiber beating degree 65–75 °SR. With the optimal conditions, the dry tensile index of the seedling bowl raw material film was between 21 and 22 N·(m·g−1), and the Z-direction tensile index was greater than 2.1 N·(m·g−1). Using wheat straw fibers and unbleached sulfite wood pulp fibers as raw materials for seedling pots, the raw material membrane of the seedling pots was made in a layered manner. The experimental study proved this feasibility. With this mixing process of raw materials, the straw fiber-based plant fiber seedling pot would meet the demands of a crop nursery after adding chemical additives. The research results provide a theoretical basis and technical support for the manufacture of the raw material membrane of the seedling pot body.

Shear modulus of single wood pulp fibers from torsion tests

The shear modulus of pulp fibers is difficult to measure and only very little literature is available on this topic. In this work we are introducing a method to measure this fiber property utilizing a custom built instrument. From the geometry of the fiber cross section, the fiber twisting angle and the applied torque, the shear modulus is derived by de Saint Venant’s theory of torsion. The deformation of the fiber is applied by a moving coil mechanism. The support of the rotating part consists of taut bands, making it nearly frictionless, which allows easy control of the torque to twist the fiber. A permanent magnet moving coil meter was fitted with a sample holder for fibers and torque references. Measurements on fine metal bands were performed to validate the instrument. The irregular shape of the fibers was reconstructed from several microtome cuts and an apparent torsion constant was computed by applying de Saint Venant’s torsion theory. Fibers from two types of industrial pulp were measured: thermomechanical pulp (TMP) and Kraft pulp. The average shear modulus was determined as (2.13 {pm } 0.36) GPa for TMP and (2.51 {pm } 0.50) GPa for Kraft fibers, respectively. The TMP fibers showed a smaller shear modulus but, due to their less collapsed state, a higher torsional rigidity than the kraft fibers.

High-yield grafting of carboxylated polymers to wood pulp fibers

Poly(ethylene-alt-maleic acid), PEMAc, is a linear polymer that, along with its isomer polyacrylic acid, has the highest carboxylic acid content of any polymer. The goal of this work was to elucidate the mechanisms that control the amount of PEMAc that is permanently fixed on pulp fibers after the impregnation of dry pulp with a dilute PEMAc solution followed by drying/heating (curing). Two mechanisms by which PEMAc is fixed to cellulose fibers were discovered, chemical, and physical fixation. With room temperature drying only physical fixation is operative. Evidence supports the explanation that physical fixation is a consequence of the slow swelling and dissolution of thick dried PEMAc deposits on fiber surfaces. Chemical fixation includes grafting to cellulose plus enhanced cohesion within thick PEMAc layers, possibly due to interchain crosslinking. The pH of the PEMAc impregnation solution determines the fixation mechanism for curing temperatures above 100 °C. Physical fixation dominates when pH > 8 whereas chemical fixation dominates for impregnation pH values ≤ 7, suggesting the curing reactions require partial or complete protonation of the succinic acid moieties. The yield of impregnated polymer fixed to the fibers after washing depends upon the fixation mechanism. When chemical fixation dominates, the yields for low and high molecular weight PEMAc doses less than 0.1 meq/g (6.3 kg PEMA/tonne dry pulp) were close to or equaled 100%. By contrast, when the primary mechanism is physical fixation, yields are ~50% for high molecular weight PEMAc and 0–20% for low MW PEMAc. These results show that high PEMAc fixation yields can be achieved under curing conditions that could be implemented in pulp drying machines producing dry market pulp.

The morphology, physical, and mechanical properties of poly (lactic acid)-based wood flour and pulp fiber biocomposites

The morphology, physical, and mechanical properties of poly (lactic acid)-based wood flour and pulp fiber biocomposites

Longitudinal and transverse low frequency viscoelastic characterization of wood pulp fibers at different relative humidity

The viscoelastic behavior of wood pulp fibers plays a fundamental role in the performance of paper and paper products. Wood pulp fibers are hierarchical composites consisting of different cell wall layers and have anisotropic properties. Since accessing the individual fibers is challenging, no measurement technique has been able to characterize the viscoelastic properties in both – the longitudinal and transverse – fiber direction yet. Here, an atomic force microscopy (AFM)-based method is applied to investigate the viscoelastic properties of wood pulp fibers at varying relative humidity (RH) in both fiber directions. Experimental creep tests have been performed to investigate the material's low frequency regime response. A spring-dashpot model has been applied to characterize the viscoelastic behavior. The results indicate surprisingly small differences of the properties between the fiber directions. Transferring the results into a spectral representation explains an opposing trend of the viscosity that is connected to the long-term behavior.

Activation of softwood Kraft pulp at high solids content by endoglucanase and lytic polysaccharide monooxygenase

The manufacturing of man-made cellulose fibers starts with the dissolution of wood pulp fibers. Pulps can dissolve at different rates and leave different amounts of undissolved particles. Thus, their properties can be modified to achieve better dissolution. Enzymatic treatments are an effective means of enhancing pulp dissolution, and this study compares the effect of endoglucanase (TrCel45A) and lytic polysaccharide monooxygenase (LPMO, TrAA9A) on bleached softwood Kraft pulp at 20 % solids content. The enzymes were applied individually and in combination. Both enzymes increased fibrillation, fines content, porosity, water retention value, crystallinity index and crystallite size, but the largest changes were achieved with the enzyme mixture. For example, fiber saturation point and water retention value increased by 64 and 37 % with TrCel45A, by 27 and 25 % with TrAA9A, and by 73 and 52 % with both TrCel45A and TrAA9A. Pulp reactivity was indirectly assessed by measuring the dissolution time in cupriethylenediamine. The average dissolution time of the reference pulp measured 642 s, while those of the pulps treated with TrCel45A, TrAA9A and their mixture were 399, 473 and 298 s, respectively. The decrease in dissolution time correlated with the increase in fines, fibrillation, porosity, and water retention value.

Evaluation of a combination of phosphorylated fibers and zeolite as a potential substitute to synthetic wetting agents in peat moss products

Water availability and pH are important factors to consider to determine the suitability of a material for use as a growing medium. Unfortunately, most horticultural substrates are characterized by their water repellency. This is the case with peat moss which is hydrophobic and acidic. Synthetic surfactants are required to improve its wettability. In this study, a combination of phosphorylated wood pulp fibers (FLP) and zeolite is proposed as a substitute to surfactants to increase the wettability of peat moss in the presence of lime, an additive generally used as fertilizer or pH regulator. Results show that lime reduces the water retention capacity of FLP. However, the addition of 15% zeolite to the peat moss/FLP system increases the pH and water retention of the substrate. The negative effect of the presence of 1 wt. % lime on the water retention of the peat moss/FLP mixture was corrected by zeolite addition. Optimal conditions were obtained at 10% zeolite for the two types of lime tested with favorable pH and water retention capacity values. Zeolite was shown to have a higher affinity than FLP for calcium ions preventing the detrimental interaction between FLP and calcium ions.

Effect of lignocellulosic fiber composition on the aquatic biodegradation of wood pulps and the isolated cellulose, hemicellulose and lignin components: kinetic modelling of the biodegradation process

The importance of renewable and environmentally friendly wood pulp fibers as an input material for single-use products has grown significantly. However, discarded single-use materials are found in the environment as litter and are sometimes disposed of in wastewater. It is important that these materials are biodegradable and environmentally benign. Wood pulp is mainly comprised of lignocellulosic material, and its composition and structure can vary depending on raw materials and processing, ultimately impacting the biodegradability. In this research, the aquatic biodegradation of five kinds of wood pulp and six different samples of isolated lignocellulosic components (cellulose, hemicellulose, and lignin) have been explored in a consistent detailed manner for the first time, and the effects of chemical composition on the biodegradation discussed. Several lignocellulosic materials were characterized using compositional analysis and were subjected to aquatic biodegradation with bio-solids from a wastewater treatment plant as an inoculum to indicate the potential to biodegrade in the environment. Cellulose and hemicellulose were readily biodegraded over a course of one month. The lignin samples were not biodegradable under these conditions, and the lignin within fibers decreased the biodegradability of the other components of the lignocellulosic fibers. It was also determined that ash and extractives negatively affect the biodegradability. The aerobic aquatic biodegradation results are useful for product designers to select different lignocellulosic materials for applications and for environmental scientists to understand the fate of these fibers in the environment.

From wood pulp fibers to tubular SiO2/C composite as anode for Li-ion battery: in-situ regulation of cellulose microfibrils by alkali solution

The microfibrils of wood pulp fibers in plant cell wall with an intrinsically regular and interlaced arrangement offer a stable porous structure. They could also provide outstanding mechanical strength and promote conductivity for Si-based materials. Upon these benefits, a method using wood pulp fibers to fabricate SiO2/C composite is proposed. In this work, the alkali pretreatment interfering hydrogen bonds in wood pulp fibers in situ results in an enlarged spatial distance among cellulose microfibrils, exposing more free-surface. This empowered homogenously inlaid SiO2 distribution along the carbon skeleton in the subsequent carbonization process. A highly mesoporous and the tubular morphology was achieved in the fabricated SiO2/C composite. Furthermore, a high initial coulombic efficiency of 84.9 % and reversible specific capacity of 1130 mA h g−1 with a coulombic efficiency of 98.8 % after 200 cycles at a current density of 0.1 A g−1 was obtained.

Mineral Nutrients, Organic Amendment, and Water Impact Decomposition of Biodegradable Containers Under Controlled Conditions

Laboratory studies were conducted to evaluate effect of soil water content, organic soil amendment, and mineral nutrient application on decomposition of three types of biodegradable containers: recycled paper, wood pulp fiber, and coconut coir over 182 days. Soil respiration was assessed through alkaline trap and titration method to determine decomposition of biodegradable containers. Percentage of carbon content remaining in the container material after 182 days was also quantified. Relative to soil water content, recycled paper containers under 40% water holding capacity (WHC) had higher carbon dioxide released than 60%WHC. Carbon analysis indicated that less carbon remained for all container types under 60% than 40%WHC. For recycled paper and coconut coir pots, treatments receiving container and soil amendment had significantly increased soil respiration. Post-experiment carbon analysis revealed less carbon remained in the recycled paper, wood pulp fiber, and coconut coir containers in the absence of organic soil amendment. For coconut coir, the interaction of container × mineral nutrients appeared to increase soil respiration with higher carbon dioxide released under biodegradable container × low mineral nutrient. This study suggests that cultural practices (i.e., irrigation and organic matter amendment) could facilitate degradation for certain biodegradable container types; however, to provide extensive cultural practice recommendations regarding biodegradable containers, more research is needed.

Properties and stabilization mechanism of oil-in-water Pickering emulsions stabilized by cellulose filaments

Cellulose filaments (CFs) are produced from wood-pulp fibres through solely mechanical treatment. They are inhomogeneous materials comprising both relatively large fibre fragments and fine fibrils. CFs can stabilize oil-in-water medium- and high-internal phase Pickering emulsions, where the presence of fibre fragments plays a critical role in emulsion stabilization by preventing CF fibrils from forming highly entangled structures. The emulsion properties are shown to be influenced by both the refining energy and CF concentration. CFs are distinct from cellulose nanofibrils (CNF) or microfibrillated cellulose (MFC), which flocculate and collapse owing to the entanglement of the homogeneous fibrous mass. Typically, other additives – surfactants or cellulose nanocrystals – are necessary to stabilize such emulsions. Further, lignin-containing CFs, produced from unbleached pulps, are particularly beneficial for emulsion stabilization at higher pH when the functional groups on lignin molecules are ionized. Our findings present CFs as potentially inexpensive, sustainable, and efficient emulsifiers for a wide variety of systems, from food to personal care products or engineering materials.

Effect of Oxidized Wood Pulp Fibers on the Performance of the Thermoplastic Corn Starch Composites

In this study, oxidized wood pulp fiber (OWPF) was prepared by oxidizing wood pulp fiber (WPF) with NaIO4, and OWPFs with different oxidation degrees were obtained and characterized by light microscope, XRD, and TG. Then, OWPFs with different oxidation degrees were incorporated into thermoplastic starch (TPS) to prepare OWPF/TPS composites. The cross-section morphology, water resistance, and physical and mechanical properties of the composites were investigated. SEM showed good dispersion of OWPF in the continuous TPS phase. The tensile strength of OWPF/TPS reached a maximum value of 5.02 MPa when the oxidation degree of OWPF was 0.5. Elongation at break of OWPF/TPS composites increased with the increasing oxidation degree of OWPF. Meanwhile, as a result of cross-linking, the water contact angle was also improved with the increased oxidation degree of OWPF. The study provided a new way to prepare a degradable TPS composite with satisfying properties to be used for packaging and catering.

One-pot synthesis of cellulose-based nonwoven web incorporated with chitosan for hemostat applications

Water-soluble chitosan and wood pulp fiber–based nonwovens were produced using wet-laying technology, and their properties were investigated for the potential application for severe hemorrhage. The pores of the wood pulp nonwovens were completely covered as the concentration of chitosan was increased. A phosphate buffer solution uptake of 997% was attained in the nonwoven loaded with chitosan concentration of 1.5 w/v%. The deposition of blood cells was found to increase with an increase in the water-soluble chitosan concentration. The blood-clotting time was found to be 170 s, making the developed nonwoven to promote blood-clotting mechanism by creating mechanical barrier to reduce the blood loss.