scholarly journals Lignin Inter-Diffusion Underlying Improved Mechanical Performance of Hot-Pressed Paper Webs

Polymers ◽  
2021 ◽  
Vol 13 (15) ◽  
pp. 2485
Author(s):  
Amanda Mattsson ◽  
Tove Joelsson ◽  
Arttu Miettinen ◽  
Jukka A. Ketoja ◽  
Gunilla Pettersson ◽  
...  
Keyword(s):  
Hot Pressing ◽  
Structural Changes ◽  
Mechanical Performance ◽  
Thermomechanical Pulp ◽  
Similar Data ◽  
Pressing Temperature ◽  
Wet Strength ◽  
Wide Range ◽  
Solids Content ◽  
Paper Webs

Broader use of bio-based fibres in packaging becomes possible when the mechanical properties of fibre materials exceed those of conventional paperboard. Hot-pressing provides an efficient method to improve both the wet and dry strength of lignin-containing paper webs. Here we study varied pressing conditions for webs formed with thermomechanical pulp (TMP). The results are compared against similar data for a wide range of other fibre types. In addition to standard strength and structural measurements, we characterise the induced structural changes with X-ray microtomography and scanning electron microscopy. The wet strength generally increases monotonously up to a very high pressing temperature of 270 °C. The stronger bonding of wet fibres can be explained by the inter-diffusion of lignin macromolecules with an activation energy around 26 kJ mol−1 after lignin softening. The associated exponential acceleration of diffusion with temperature dominates over other factors such as process dynamics or final material density in setting wet strength. The optimum pressing temperature for dry strength is generally lower, around 200 °C, beyond which hemicellulose degradation begins. By varying the solids content prior to hot-pressing for the TMP sheets, the highest wet strength is achieved for the completely dry web, while no strong correlation was observed for the dry strength.

Effect of Blending Modification on Tensile Performance of CPE/PVC

2011 ◽  
Vol 284-286 ◽  
pp. 1732-1735
Author(s):  
Xiao Ling Xie ◽  
Wen Hai Li ◽  
Ying Hui Wei
Keyword(s):  
Tensile Strength ◽  
Polyvinyl Chloride ◽  
Hot Pressing ◽  
Mechanical Performance ◽  
Dioctyl Phthalate ◽  
Test Results ◽  
Pressing Temperature ◽  
Chlorinated Polyethylene ◽  
Breaking Elongation ◽  
Tensile Performance

The samples were modified by using chlorinated polyethylene (CPE) to increase the toughness and using dioctyl phthalate (DOP) to increase the plasticity. The tensile strength and breaking elongation of the samples were studied by changing the chlorinated polyethylene (CPE) and dioctyl phthalate (DOP) contents and the hot-pressing temperature. It was shown by the test results that, with the increase of chlorinated polyethylene (CPE) and dioctyl phthalate (DOP) contents, the tensile strength of the samples was decreased while the breaking elongation was increased. By increasing the hot-pressing temperature, the blending effect between polyvinyl chloride (PVC) and chlorinated polyethylene (CPE) as well as the mechanical performance of the samples were increased, however, over-high hot-pressing temperature would result in plasticizer precipitation.

Study on the Strength Properties of PPTA Paper with Response Surface Methodology

2013 ◽  
Vol 756-759 ◽  
pp. 54-59
Author(s):  
Ai Min Tang ◽  
Shan Zhao ◽  
Chao Feng Jia
Keyword(s):  
Tensile Strength ◽  
Response Surface Methodology ◽  
Response Surface ◽  
Hot Pressing ◽  
Strength Properties ◽  
Pressing Pressure ◽  
Pressing Temperature ◽  
Wet Strength ◽  
Quadratic Formula ◽  
And Control

Response Surface Methodology (RSM) was used to study the relationship between the strength properties of poly ( p-phenylene terephthalamide)-PPTA paper and the preparation parameters, such as hot pressing temperature, hot pressing pressure, proportion of PPTA short-cut fiber and beating degree of PPTA-pulp. The results showed that: hot pressing temperature, hot pressing pressure have highly significant influences on the tensile strength and wet strength. The proportion of PPTA short-cut fiber has significant effects on the tensile strength and wet strength. The beating degree of PPTA-pulp also affected the tensile strength significantly. At the same time, the tensile strength was significantly influenced by the interaction between hot pressing temperature and the proportion of PPTA short-cut fiber as well as the interaction between hot pressing temperature and the beating degree of PPTA-pulp. The interaction between hot pressing temperature and hot pressing pressure has significant influences on wet strength, whereas the other factor interactions were not significant. The quadratic formula was established by optimizing the results of multiple regressions. And the model was highly consistent with the experiment. This model could be used to analyze and predict the main strength properties of PPTA paper and also might be used to optimize the production process of PPTA paper and control its quality.

scholarly journals Effect of Hot-Pressing Temperature on Characteristics of Straw-Based Binderless Fiberboards with Pulping Effluent

Materials ◽  
2019 ◽  
Vol 12 (6) ◽  
pp. 922 ◽  
Author(s):  
Jiajun Wang ◽  
Bo Wang ◽  
Junliang Liu ◽  
Lin Ni ◽  
Jianzhang Li
Keyword(s):  
Hot Pressing ◽  
Mechanical Performance ◽  
Thermal Transitions ◽  
Surface Color ◽  
Pressing Temperature ◽  
Surface Appearance ◽  
Property Data ◽  
Ft Ir ◽  
The Difference

This study aimed to improve straw-based fiberboard properties without resins by adding pulping effluent as well as to investigate the difference among boards under variable hot-pressing temperatures. The characterization of fiberboards produced from wheat straw under pressing temperatures ranging from 160 to 200 °C was first described. The surface appearance, surface chemistry, thermal transitions, and mechanical performance of the boards were evaluated to investigate the effect of varying hot-pressing temperature. The results indicated that the surface color of boards became darker when the temperature was above 190 °C. Additionally, Fourier transform infrared (FT-IR) measurements showed that more low-molecular constituents and hydrogen bonds were produced under higher pressing temperatures. Furthermore, the physical and mechanical property data were analyzed statistically using one-way analysis of variance (ANOVA) and Tukey’s tests (α = 0.05). The results demonstrated that straw-based fiberboards with effluent under 190 °C exhibited superior strength and water resistance capacities, and showed great potential in commercial decorating and packaging applications.

The Fiberboard of Hot Pressing Process Optimization and Combination Performance Characterization

2010 ◽  
Vol 44-47 ◽  
pp. 2278-2282
Author(s):  
Ming Hui Guo ◽  
Jian Peng Hu
Keyword(s):  
Hot Pressing ◽  
Mechanical Performance ◽  
Wood Fiber ◽  
Pressing Pressure ◽  
Interface Properties ◽  
Test Results ◽  
Pressing Temperature ◽  
Pressing Time ◽  
Instrument Analysis ◽  
Natural Wood

To pack a certain quality ratio ammonium lignosulfonate / urea as a filler into the natural wood fiber, Using flat pressure process fiberboard materials, Optimize the hot pressing technique that the filler is 20% (The quality ratio of lignosulfonate/ urea is 5: 3), slab moisture content is 13%, hot-pressing temperature is 190°C; hot-pressing time is 7 minutes, hot-pressing pressure is 2MPa and 1% paraffin emulsion. Verifying test results show that mechanical performance is stable and reliable process. Analyze the reactivity of fiberboard packing, fiber gathered, the microstructure of interface properties with the application of FTIR, XRD and ESEM and other modern instrument analysis technology.

Improving paper wet strength via increased lignin content and hot-pressing temperature

TAPPI Journal ◽  
2020 ◽  
Vol 19 (10) ◽  
pp. 487-497
Author(s):  
TOVE JOELSSON ◽  
GUNILLA PETTERSSON ◽  
SVEN NORGREN ◽  
ANNA SVEDBERG ◽  
HANS HOGLUND ◽  
...  
Keyword(s):  
Hot Pressing ◽  
Lignin Content ◽  
Pilot Scale ◽  
Strength Properties ◽  
High Yield ◽  
Kraft Pulps ◽  
Pressing Temperature ◽  
Wet Strength ◽  
Tensile Index ◽  
Reference Samples

It is known that the strength properties of wood-based paper materials can be enhanced via hot-pressing techniques. Today, there is a desire not only for a change from fossil-based packaging materials to new sustainable bio-based materials, but also for more effective and eco-friendly solutions for improving the dry and wet strength of paper and board. Against this background, hot pressing of paper made from high yield pulp (HYP), rich in lignin, becomes highly interesting. This study investigated the influence of pressing temperature and native lignin content on the properties of paper produced by means of hot pressing. Kraft pulps of varied lignin content (kappa numbers: 25, 50, 80) were produced at pilot scale from the same batch by varying the cooking time. We then studied the effect of lignin content by evaluating the physical properties of Rapid Köthen sheets after hot pressing in the temperature range of 20°C–200°C with a constant nip pressure of 7 MPa. The pilot-scale cooked pulps were compared with reference samples of mill-produced northern bleached soft-wood kraft (NBSK) pulp and mill-produced chemithermomechanical pulp (CTMP). Generally, the results demonstrated that lignin content had a significant effect on both dry and wet tensile index. All of the pilot cooked pulps with increased lignin content had a higher tensile index than the reference NBSK pulp. To obtain high tensile index, both dry and wet, the pressing temperature should be set high, preferably at least 200°C; that is, well above the glass transition temperature (Tg) for lignin. Moreover, the lignin content should preferably also be high. All kraft pulps investigated in this study showed a linear relationship between wet strength and lignin content.

scholarly journals High strength paper from high yield pulps by means of hot-pressing

2020 ◽  
Vol 35 (2) ◽  
pp. 195-204
Author(s):  
Tove Joelsson ◽  
Gunilla Pettersson ◽  
Sven Norgren ◽  
Anna Svedberg ◽  
Hans Höglund ◽  
...  
Keyword(s):  
Tensile Strength ◽  
Hot Pressing ◽  
Kraft Pulp ◽  
High Strength ◽  
Strength Properties ◽  
High Yield ◽  
Thermomechanical Pulp ◽  
Wet Strength ◽  
Chemical Pulp ◽  
Bleached Kraft Pulp

AbstractThe hypothesis is that it should be possible to modify papermaking conditions in line with the softening properties of high yield pulp fibres and achieve similar strength properties to conventional chemical pulp based paper. We therefore investigated the rheological and physical properties of high yield pulp based papers during hot-pressing. Our results confirm that increased temperature combined with sufficient pressure enables permanent densification by softening of lignin, producing very high tensile strength. This treatment also significantly improved the wet tensile strength in comparison to bleached kraft pulp without using wet strength agents. The high yield pulps used here were spruce based thermomechanical pulp, chemi-thermomechanical pulp, and high temperature chemi-thermomechanical pulp, and birch-aspen based neutral sulphite semi chemical pulp, with spruce-pine based bleached kraft pulp as reference. Rapid Köhten sheets of 150\hspace{0.1667em}\text{g}/{\text{m}^{2}} and 50 % dryness were hot-pressed in a cylinder-press at 20–200 °C, 7 MPa, and 1 m/min. The mechanical properties showed great improvements in these high yield pulp papers, with tensile index increased to 75 kNm/kg and compression strength index to 45 kNm/kg; levels close to and better than bleached kraft. Wet strength increased to 16 Nm/g compared to 5 Nm/g for bleached kraft.

scholarly journals Effects of a Twin-Screw Extruder Equipped with a Molten Resin Reservoir on the Mechanical Properties and Microstructure of Recycled Waste Plastic Polyethylene Pellet Moldings

Polymers ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 1058
Author(s):  
Hikaru Okubo ◽  
Haruka Kaneyasu ◽  
Tetsuya Kimura ◽  
Patchiya Phanthong ◽  
Shigeru Yao
Keyword(s):  
Mechanical Properties ◽  
Mechanical Performance ◽  
Value Added ◽  
Industrial Applications ◽  
Twin Screw Extruder ◽  
Screw Extruder ◽  
Polymer Properties ◽  
Wide Range ◽  
Twin Screw ◽  
Recycled Plastics

Each year, increasing amounts of plastic waste are generated, causing environmental pollution and resource loss. Recycling is a solution, but recycled plastics often have inferior mechanical properties to virgin plastics. However, studies have shown that holding polymers in the melt state before extrusion can restore the mechanical properties; thus, we propose a twin-screw extruder with a molten resin reservoir (MSR), a cavity between the screw zone and twin-screw extruder discharge, which retains molten polymer after mixing in the twin-screw zone, thus influencing the polymer properties. Re-extruded recycled polyethylene (RPE) pellets were produced, and the tensile properties and microstructure of virgin polyethylene (PE), unextruded RPE, and re-extruded RPE moldings prepared with and without the MSR were evaluated. Crucially, the elongation at break of the MSR-extruded RPE molding was seven times higher than that of the original RPE molding, and the Young’s modulus of the MSR-extruded RPE molding was comparable to that of the virgin PE molding. Both the MSR-extruded RPE and virgin PE moldings contained similar striped lamellae. Thus, MSR re-extrusion improved the mechanical performance of recycled polymers by optimizing the microstructure. The use of MSRs will facilitate the reuse of waste plastics as value-added materials having a wide range of industrial applications.

scholarly journals Entangling Lattice-Trapped Bosons with a Free Impurity: Impact on Stationary and Dynamical Properties

Entropy ◽  
2021 ◽  
Vol 23 (3) ◽  
pp. 290
Author(s):  
Maxim Pyzh ◽  
Kevin Keiler ◽  
Simeon I. Mistakidis ◽  
Peter Schmelcher
Keyword(s):  
Structural Changes ◽  
Many Body ◽  
Wide Range ◽  
Entropy Measures ◽  
Particle Level ◽  
The Many ◽  
The One ◽  
Tunneling Dynamics ◽  
The Individual ◽  
Trapped Bosons

We address the interplay of few lattice trapped bosons interacting with an impurity atom in a box potential. For the ground state, a classification is performed based on the fidelity allowing to quantify the susceptibility of the composite system to structural changes due to the intercomponent coupling. We analyze the overall response at the many-body level and contrast it to the single-particle level. By inspecting different entropy measures we capture the degree of entanglement and intraspecies correlations for a wide range of intra- and intercomponent interactions and lattice depths. We also spatially resolve the imprint of the entanglement on the one- and two-body density distributions showcasing that it accelerates the phase separation process or acts against spatial localization for repulsive and attractive intercomponent interactions, respectively. The many-body effects on the tunneling dynamics of the individual components, resulting from their counterflow, are also discussed. The tunneling period of the impurity is very sensitive to the value of the impurity-medium coupling due to its effective dressing by the few-body medium. Our work provides implications for engineering localized structures in correlated impurity settings using species selective optical potentials.

scholarly journals Modelling the elastic mechanical properties of bioactive glass-derived scaffolds

2020 ◽  
Vol 6 (1) ◽  
pp. 50-56
Author(s):  
Francesco Baino ◽  
Elisa Fiume
Keyword(s):  
Elastic Properties ◽  
Poisson’S Ratio ◽  
Mechanical Performance ◽  
Solid Material ◽  
Poisson's Ratio ◽  
Predictive Capability ◽  
Shear Moduli ◽  
Wide Range ◽  
Constitutive Parameters ◽  
The Relationship

AbstractPorosity is known to play a pivotal role in dictating the functional properties of biomedical scaffolds, with special reference to mechanical performance. While compressive strength is relatively easy to be experimentally assessed even for brittle ceramic and glass foams, elastic properties are much more difficult to be reliably estimated. Therefore, describing and, hence, predicting the relationship between porosity and elastic properties based only on the constitutive parameters of the solid material is still a challenge. In this work, we quantitatively compare the predictive capability of a set of different models in describing, over a wide range of porosity, the elastic modulus (7 models), shear modulus (3 models) and Poisson’s ratio (7 models) of bioactive silicate glass-derived scaffolds produced by foam replication. For these types of biomedical materials, the porosity dependence of elastic and shear moduli follows a second-order power-law approximation, whereas the relationship between porosity and Poisson’s ratio is well fitted by a linear equation.

scholarly journals Ligand-induced structural changes analysis of ribose-binding protein as studied by molecular dynamics simulations

2021 ◽  
pp. 1-12
Author(s):  
Haiyan Li ◽  
Zanxia Cao ◽  
Guodong Hu ◽  
Liling Zhao ◽  
Chunling Wang ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Structural Changes ◽  
Binding Protein ◽  
Network Models ◽  
Md Simulations ◽  
Protein Domain ◽  
Opening Angle ◽  
Conformation Changes ◽  
Wide Range ◽  
Ribose Binding Protein

BACKGROUND: The ribose-binding protein (RBP) from Escherichia coli is one of the representative structures of periplasmic binding proteins. Binding of ribose at the cleft between two domains causes a conformational change corresponding to a closure of two domains around the ligand. The RBP has been crystallized in the open and closed conformations. OBJECTIVE: With the complex trajectory as a control, our goal was to study the conformation changes induced by the detachment of the ligand, and the results have been revealed from two computational tools, MD simulations and elastic network models. METHODS: Molecular dynamics (MD) simulations were performed to study the conformation changes of RBP starting from the open-apo, closed-holo and closed-apo conformations. RESULTS: The evolution of the domain opening angle θ clearly indicates large structural changes. The simulations indicate that the closed states in the absence of ribose are inclined to transition to the open states and that ribose-free RBP exists in a wide range of conformations. The first three dominant principal motions derived from the closed-apo trajectories, consisting of rotating, bending and twisting motions, account for the major rearrangement of the domains from the closed to the open conformation. CONCLUSIONS: The motions showed a strong one-to-one correspondence with the slowest modes from our previous study of RBP with the anisotropic network model (ANM). The results obtained for RBP contribute to the generalization of robustness for protein domain motion studies using either the ANM or PCA for trajectories obtained from MD.

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