scholarly journals Enhancement of Interface between Lignocellulosic Fibers and Polypropylene Matrix via the Structure Alteration of Lignin at Elevated Temperatures

Materials ◽  
2020 ◽  
Vol 13 (23) ◽  
pp. 5428
Author(s):  
Zhen Dong ◽  
Na Li ◽  
Aixue Dong ◽  
Bomou Ma ◽  
Chongwen Yu ◽  
...  
Keyword(s):  
Surface Energy ◽  
Elevated Temperatures ◽  
Fiber Strength ◽  
Alkali Treatment ◽  
Fiber Surface ◽  
Lignocellulosic Fibers ◽  
Jute Fibers ◽  
Polypropylene Matrix ◽  
Lignocellulose Fibers ◽  
The Impact

This paper investigated the feasibility of enhancing the interface between lignocellulosic fibers and a polypropylene matrix via structure alteration of lignin at elevated temperatures. Alkali treatment can remove gum substances from lignocellulose fibers effectively at elevated temperatures but easily causes damages to fiber strength. In previous studies on directional delignification of lignocellulosic fibers, loss of fiber strength is avoided but condensation and degradation of lignin are accelerated. So far, few reports have been available on the effect of lignin structures on the interface between fibers and a matrix. In this study, jute fibers with different lignin structures are produced at 100 and 130 °C for reinforcing a polypropylene matrix. The interface between the fibers and matrix is analyzed. The result shows that decrease in aliphatic hydroxyl concentration by 9.5% at 130 °C from 3 to 5 h contributes to a 14.2% decrease in the surface energy of jute fibers. Meanwhile, the polydispersity index of lignin decreases from 1.21 to 1.15. Centralized distribution of lignin molecule-weight and reduction in fiber surface energy improves the interface between the fibers and matrix, which manifests as a 30.8% increase in the impact strength of the composites. Similar improvement is not observed in the composites reinforced with jute fibers at 100 °C, due to the absence of lignin-structure changes. This paper provides a new strategy to improve the interface between lignocellulose fibers and a hydrophobic matrix.

Surface Treatment Influence on the Mechanical Behavior of Jute Fiber Reinforced Composites

2011 ◽  
Vol 410 ◽  
pp. 122-125 ◽  
Author(s):  
J.M. Byeon ◽  
Gi Beop Nam ◽  
J.W. Kim ◽  
B.S. Kim ◽  
Jung I. Song
Keyword(s):  
Mechanical Properties ◽  
Surface Treatment ◽  
Plasma Treatment ◽  
Alkali Treatment ◽  
Fiber Surface ◽  
Fiber Reinforced Composites ◽  
Reinforced Composites ◽  
Jute Fibers ◽  
Fiber Surface Treatment ◽  
Flexural Tests

In this study, Jute fibers reinforced polypropylene (JFRP) composites were manufactured by injection molding technique. Prior to fabrication of composites, fiber surface was treated by Alkali and Plasma for a rise in fibers properties. Furthermore, after the alkali treatment attempt plasma treatment for the fiber surface treatment to obtain a batter value. In order to improve the affinity and adhesion between fibers and thermoplastic matrices during manufacturing, Maleic anhydride (MA) as a coupling agent have been employed. Untreated and treated surfaces of jute fibers were characterized using SEM. Tensile and flexural tests were carried out to evaluate the composite mechanical properties. Tensile test indicated that 3% of the alkali treatment and 2min plasma treatment fiber has highest tensile strength.

Improvement on the interfacial compatibility of jute fiber-reinforced polypropylene composites by different surface treatments

2018 ◽  
Vol 49 (7) ◽  
pp. 906-922
Author(s):  
Xuan Liu ◽  
Sen-Jie Hao ◽  
Yi-Hua Cui ◽  
Hai-yan Chen
Keyword(s):  
Surface Energy ◽  
Alkali Treatment ◽  
Fiber Reinforced Composites ◽  
Jute Fiber ◽  
Reinforced Composites ◽  
Fiber Reinforced ◽  
Polypropylene Composites ◽  
Jute Fibers ◽  
Interfacial Compatibility ◽  
Treated Fiber

The interfacial compatibility possessed critical effect on the performance of jute fiber-reinforced composites. In order to improve the interfacial compatibility of jute fiber-reinforced polypropylene composites, jute fibers were treated by alkali treatment, ethylenediamine/alkali treatment and acid/alkali treatment. Through analysis by scanning electron microscopy, atomic force microscopy, Fourier transform infrared, X-ray diffraction, surface energy measurement, and tensile strength test, the acid/alkali treatment was deemed as the most efficient method for improving the surface properties of jute fibers among three kinds of surface treatments. The interfacial compatibility of treated fiber-reinforced composites was enhanced significantly, which attributed to the improvement of surface properties of jute fibers. Due to the acidic hydrolysis of acid treatment, the surface energy of acid/alkali treated fibers was increased by 45.58% compared with the control fibers. The tensile and bending strength of acid/alkali treated fiber-reinforced composites were enhanced by 34.80% and 22.53%, respectively. Therefore, the acid/alkali treatment was potential and competitive surface treatment to enhance the interfacial compatibility of jute fiber-reinforced composites.

Influence of Fiber Surface Energy on Mechanical Properties of Sisal Fiber - Bio Based Epoxy Composites

2019 ◽  
Vol 35 (4) ◽  
pp. 485-496
Author(s):  
S. RAJKUMAR ◽  
◽  
R. JOSEPH BENSINGH ◽  
M. ABDUL KADER ◽  
SANJAY K NAYAK ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Surface Energy ◽  
Fiber Surface ◽  
Epoxy Composites ◽  
Sisal Fiber

scholarly journals Influence of Alkali Treatment on the Microstructure and Mechanical Properties of Coir and Abaca Fibers

Materials ◽  
2021 ◽  
Vol 14 (10) ◽  
pp. 2636
Author(s):  
Petr Valášek ◽  
Miroslav Müller ◽  
Vladimír Šleger ◽  
Viktor Kolář ◽  
Monika Hromasová ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Composite Materials ◽  
Alkali Treatment ◽  
Fiber Surface ◽  
Cellulose Fibers ◽  
Sem Analysis ◽  
Experimental Program ◽  
Time Interval ◽  
The European Union ◽  
Vegetable Fibers

Composite materials with natural fillers have been increasingly used as an alternative to synthetically produced materials. This trend is visible from a representation of polymeric composites with natural cellulose fibers in the automotive industry of the European Union. This trend is entirely logical, owing to a preference for renewable resources. The experimental program itself follows pronounced hypotheses and focuses on a description of the mechanical properties of untreated and alkali-treated natural vegetable fibers, coconut and abaca fibers. These fibers have great potential for use in composite materials. The results and discussion sections contribute to an introduction of an individual methodology for mechanical property assessment of cellulose fibers, and allows for a clear definition of an optimal process of alkalization dependent on the content of hemicellulose and lignin in vegetable fibers. The aim of this research was to investigate the influence of alkali treatment on the surface microstructure and tensile properties of coir and abaca fibers. These fibers were immersed into a 5% solution of NaOH at laboratory temperature for a time interval of 30 min, 1 h, 2 h, 3 h, 6 h, 12 h, 24 h, and 48 h, rinsed and dried. The fiber surface microstructures before and after the alkali treatment were evaluated by SEM (scanning electron microscopy). SEM analysis showed that the alkali treatment in the NaOH solution led to a gradual connective material removal from the fiber surface. The effect of the alkali is evident from the visible changes on the surface of the fibers.

scholarly journals Fire Resistance Behaviour of Geopolymer Concrete:An Overview

Buildings ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 82
Author(s):  
Salmabanu Luhar ◽  
Demetris Nicolaides ◽  
Ismail Luhar
Keyword(s):  
Compressive Strength ◽  
Thermal Resistance ◽  
Building Materials ◽  
Elevated Temperatures ◽  
Construction Materials ◽  
Flexural Behavior ◽  
Thermal Shrinkage ◽  
Physico Chemical ◽  
The Impact ◽  
Loss Of Strength

Even though, an innovative inorganic family of geopolymer concretes are eye-catching potential building materials, it is quite essential to comprehend the fire and thermal resistance of these structural materials at a very high temperature and also when experiencing fire with a view to make certain not only the safety and security of lives and properties but also to establish them as more sustainable edifice materials for future. The experimental and field observations of degree of cracking, spalling and loss of strength within the geopolymer concretes subsequent to exposure at elevated temperature and incidences of occurrences of disastrous fires extend an indication of their resistance against such severely catastrophic conditions. The impact of heat and fire on mechanical attributes viz., mechanical-compressive strength, flexural behavior, elastic modulus; durability—thermal shrinkage; chemical stability; the impact of thermal creep on compressive strength; and microstructure properties—XRD, FTIR, NMR, SEM as well as physico-chemical modifications of geopolymer composites subsequent to their exposures at elevated temperatures is reviewed in depth. The present scientific state-of-the-art review manuscript aimed to assess the fire and thermal resistance of geopolymer concrete along with its thermo-chemistry at a towering temperature in order to introduce this novel, most modern, user and eco-benign construction materials as potentially promising, sustainable, durable, thermal and fire-resistant building materials promoting their optimal and apposite applications for construction and infrastructure industries.

scholarly journals Thermodynamic Behavior of Fe-Mn and Fe-Mn-Ag Powder Mixtures during Selective Laser Melting

Metals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 234
Author(s):  
Jakob Kraner ◽  
Jožef Medved ◽  
Matjaž Godec ◽  
Irena Paulin
Keyword(s):  
Selective Laser Melting ◽  
Manganese Oxides ◽  
Elevated Temperatures ◽  
Manganese Content ◽  
Chemical Compositions ◽  
Metal Powders ◽  
Laser Melting ◽  
Powder Mixtures ◽  
Ε Martensite ◽  
The Impact

Additive manufacturing is a form of powder metallurgy, which means the properties of the initial metal powders (chemical composition, powder morphology and size) impact the final properties of the resulting parts. A complete characterization, including thermodynamic effects and the behavior of the metal powders at elevated temperatures, is crucial when planning the manufacturing process. The analysis of the Fe-Mn and Fe-Mn-Ag powder mixtures, made from pure elemental powders, shows a high susceptibility to sintering in the temperature interval from 700 to 1000 °C. Here, numerous changes to the manganese oxides and the αMn to βMn transformation occurred. The problems of mechanically mixed powders, when using selective laser melting, were highlighted by the low flowability, which led to a less controllable process, an uncontrolled arrangement of the powder and a large percentage of burnt manganese. All this was determined from the altered chemical compositions of the produced parts. The impact of the increased manganese content on the decreased probability of the transformation from γ-austenite to ε-martensite was confirmed. The ε-martensite in the microstructure increased the hardness of the material, but at the same time, its magnetic properties reduce the usefulness for medical applications. However, the produced parts had comparable elongations to human bone.

scholarly journals Measuring the impact of a new snow model using surface energy budget process relationships

2020 ◽  
Author(s):  
Jonathan Day ◽  
Gabriele Arduini ◽  
Irina Sandu ◽  
Linus Magnusson ◽  
Anton Beljaars ◽  
...  
Keyword(s):  
Surface Energy ◽  
Energy Budget ◽  
Surface Energy Budget ◽  
Budget Process ◽  
Snow Model ◽  
The Impact

scholarly journals R-BPMV-Mediated Resistance to Bean pod mottle virus in Phaseolus vulgaris L. Is Heat-Stable but Elevated Temperatures Boost Viral Infection in Susceptible Genotypes

Viruses ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 1239
Author(s):  
Chouaïb Meziadi ◽  
Julie Lintz ◽  
Masoud Naderpour ◽  
Charlotte Gautier ◽  
Sophie Blanchet ◽  
...  
Keyword(s):  
Elevated Temperature ◽  
Phaseolus Vulgaris ◽  
Elevated Temperatures ◽  
Heat Waves ◽  
Dominant Gene ◽  
Atmospheric Temperature ◽  
Mottle Virus ◽  
Bean Pod Mottle Virus ◽  
Heat Stable ◽  
The Impact

In the context of climate change, elevated temperature is a major concern due to the impact on plant–pathogen interactions. Although atmospheric temperature is predicted to increase in the next century, heat waves during summer seasons have already become a current problem. Elevated temperatures strongly influence plant–virus interactions, the most drastic effect being a breakdown of plant viral resistance conferred by some major resistance genes. In this work, we focused on the R-BPMV gene, a major resistance gene against Bean pod mottle virus in Phaseolus vulgaris. We inoculated different BPMV constructs in order to study the behavior of the R-BPMV-mediated resistance at normal (20 °C) and elevated temperatures (constant 25, 30, and 35 °C). Our results show that R-BPMV mediates a temperature-dependent phenotype of resistance from hypersensitive reaction at 20 °C to chlorotic lesions at 35 °C in the resistant genotype BAT93. BPMV is detected in inoculated leaves but not in systemic ones, suggesting that the resistance remains heat-stable up to 35 °C. R-BPMV segregates as an incompletely dominant gene in an F2 population. We also investigated the impact of elevated temperature on BPMV infection in susceptible genotypes, and our results reveal that elevated temperatures boost BPMV infection both locally and systemically in susceptible genotypes.

Study on Thermal, Thermo-Mechanical, and Flexural Properties of Jute Fiber Surface Modification and Its Reinforced Composite

2021 ◽  
Vol 8 (5) ◽  
pp. 11-17
Author(s):  
Syed Rashedul Islam ◽  
Abeer Alassod ◽  
Mohammed Kayes Patoary ◽  
Tayyab Naveed ◽  
Md Arshad Ali ◽  
...  
Keyword(s):  
Natural Fiber ◽  
Natural Fibers ◽  
Fiber Surface ◽  
Jute Fiber ◽  
Flexural Properties ◽  
Reinforced Composites ◽  
Acid Pretreatment ◽  
Chemical Treatments ◽  
Jute Fibers ◽  
Composite Properties

In recent years, reinforced composites from biodegradable and natural fibers have a worldwide scope for advanced applications. However, the core limitation of natural fiber reinforced composites are poor consistency among supporting fibers and the matrix. Therefore, optimal structural performance of fibers and matrix is desirable. In this study, chemical treatments (i.e., alkali pretreatment, acid pretreatment, and scouring) were applied to jute fibers for improvement of composite properties. Thermal, thermo-mechanical, and flexural properties, and surface morphology, of untreated and treated jute fibers were studied on the treated fibers. Jute fiber/epoxy composite properties were analyzed by thermogravimetric analysis (TGA), flexural strength and modulus, and dynamic mechanical analysis (DMA). The chemical treatments had a significant impact on the properties of jute fiber composites.

Assessing the impact of exceptional inter-annual climatic variability on rates of net ecosystem carbon dioxide exchange at Clara bog.

2021 ◽  
Author(s):  
Matthew Saunders ◽  
Ruchita Ingle ◽  
Shane Regan
Keyword(s):  
Water Table ◽  
Elevated Temperatures ◽  
Ecosystem Respiration ◽  
Anthropogenic Activities ◽  
Climatic Variability ◽  
Growing Season ◽  
Carbon Dioxide Exchange ◽  
Mean Annual Temperature ◽  
Monitoring Networks ◽  
The Impact

<p>Peatland ecosystems are integral to the mitigation of climate change as they represent significant terrestrial carbon sinks. In Ireland, peatlands cover ~20% of the land area but hold up to 75% of the soil organic carbon stock however many of these ecosystems (~85% of the total area) have been degraded due to anthropogenic activities such as agriculture, forestry and extraction for horticulture or energy. Furthermore, the carbon stocks that remain in these systems are vulnerable to inter-annual variation in climate, such as changes in precipitation and temperature, which can alter the hydrological status of these systems leading to changes in key biogeochemical processes and carbon and greenhouse gas exchange.  During 2018 exceptional drought and heatwave conditions were reported across Northwestern Europe, where reductions in precipitation coupled with elevated temperatures were observed. Exceptional inter-annual climatic variability was also observed at Clara bog, a near natural raised bog in the Irish midlands when data from 2018 and 2019 were compared. Precipitation in 2018 was ~300 mm lower than 2019 while the average mean annual temperature was 0.5°C higher. The reduction in precipitation, particularly during the growing season in 2018, consistently lowered the water table where ~150 consecutive days where the water table was >5cm below the surface of the bog were observed at the central ecotope location. The differing hydrological conditions between years resulted in the study area, as determined by the flux footprint of the eddy covariance tower, acting as a net source of carbon of 53.5 g C m<sup>-2</sup> in 2018 and a net sink of 125.2 g C m<sup>-2</sup> in 2019. The differences in the carbon dynamics between years were primarily driven by enhanced ecosystem respiration (R<sub>eco</sub>) and lower rates of Gross Primary Productivity (GPP) in the drier year, where the maximum monthly ratio of GPP:R<sub>eco</sub> during the growing season was 0.96 g C m<sup>-2</sup> month in 2018 and 1.14 g C m<sup>-2</sup> month in 2019. This study highlights both the vulnerability and resilience of these ecosystems to exceptional inter-annual climatic variability and emphasises the need for long-term monitoring networks to enhance our understanding of the impacts of these events when they occur.</p>

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