scholarly journals Enhancing an Aerospace Grade Benzoxazine Resin by Means of Graphene Nanoplatelet Addition

Polymers ◽  
2021 ◽  
Vol 13 (15) ◽  
pp. 2544
Author(s):  
Vanessa García-Martínez ◽  
Maria R. Gude ◽  
Silvia Calvo ◽  
Alejandro Ureña
Keyword(s):  
Thermal Conductivity ◽  
Mechanical Performance ◽  
Water Environment ◽  
Barrier Properties ◽  
Complete Characterization ◽  
Graphene Nanoplatelets ◽  
Hot Water ◽  
Maximum Water

Two different contents of graphene nanoplatelets (GNPs: 0.5 and 2 wt.%) were introduced into benzoxazine resin. The main objective of this work is to obtain a polymeric nanocomposite with multifunctional properties as high electrical and thermal conductivity, maintaining or improving its mechanical performance. The quality of the dispersion, performed with a three-roll calender, was studied. Afterward, a complete characterization of the nanocomposites was carried out in order to analyse the benefits of neat resin. The main features of the nanocomposites such as the mechanical and thermo-mechanical properties, their electrical and thermal conductivity and the behaviour under hygrothermal aging, were evaluated. Results allowed us to confirm that benzoxazine/GNP composites exhibited an increase in the tensile strength of polymeric matrix which was accompanied by a rise in elongation at break. The electrical and thermal conductivities exhibited a remarkable increment with the addition of 2 wt.% of GNPs (six orders of magnitude and 49% respectively). Finally, the barrier properties of benzoxazine resin were also favoured with the presence of GNPs because the maximum water absorbed in a hot-water environment decreased from 2.52% to 2.14% when 0.5 wt.% of graphene nanoplatelets was added.

scholarly journals A Comprehensive Investigation on 3D Printing of Polyamide 11 and Thermoplastic Polyurethane via Multi Jet Fusion

Polymers ◽  
2021 ◽  
Vol 13 (13) ◽  
pp. 2139
Author(s):  
Wei Shian Tey ◽  
Chao Cai ◽  
Kun Zhou
Keyword(s):  
Tensile Strength ◽  
Flexural Strength ◽  
Wear Rate ◽  
Mechanical Performance ◽  
Thermoplastic Polyurethane ◽  
Print Quality ◽  
Polyamide 11 ◽  
Powder Bed

Multi Jet Fusion (MJF) is a recently developed polymeric powder bed fusion (PBF) additive manufacturing technique that has received considerable attention in the industrial and scientific community due to its ability to fabricate functional and complex polymeric parts efficiently. In this work, a systematic characterization of the physicochemical properties of MJF-certified polyamide 11 (PA11) and thermoplastic polyurethane (TPU) powder was conducted. The mechanical performance and print quality of the specimens printed using both powders were then evaluated. Both PA11 and TPU powders showed irregular morphology with sharp features and had broad particle size distribution, but such features did not impair their printability significantly. According to the DSC scans, the PA11 specimen exhibited two endothermic peaks, while the TPU specimen exhibited a broad endothermic peak (116–150 °C). The PA11 specimens possessed the highest tensile strength in the Z orientation, as opposed to the TPU specimens which possessed the lowest tensile strength along the same orientation. The flexural properties of the PA11 and TPU specimens displayed a similar anisotropy where the flexural strength was highest in the Z orientation and lowest in the X orientation. The porosity values of both the PA11 and the TPU specimens were observed to be the lowest in the Z orientation and highest in the X orientation, which was the opposite of the trend observed for the flexural strength of the specimens. The PA11 specimen possessed a low coefficient of friction (COF) of 0.13 and wear rate of 8.68 × 10−5 mm3/Nm as compared to the TPU specimen, which had a COF of 0.55 and wear rate of 0.012 mm3/Nm. The PA11 specimens generally had lower roughness values on their surfaces (Ra < 25 μm), while the TPU specimens had much rougher surfaces (Ra > 40 μm). This investigation aims to uncover and explain phenomena that are unique to the MJF process of PA11 and TPU while also serving as a benchmark against similar polymeric parts printed using other PBF processes.

Preparation and Characterization of GNP/Nylon Composites

2014 ◽  
Vol 556-562 ◽  
pp. 339-342 ◽  
Author(s):  
Bao Feng Xu ◽  
Zhi Dan Lin ◽  
Jiang Ming Chen ◽  
Jun Lin
Keyword(s):  
Mechanical Properties ◽  
Thermal Conductivity ◽  
Thermal Properties ◽  
Graphene Nanoplatelets ◽  
Melt Blending ◽  
Blending Method

Graphene nanoplatelets (GNP) and nylon (PA) have been often used as thermal filler and matrix and respectively to produce composites. In this work, PA6/PA66/GNP thermal composites were prepared via a melt blending method. Mechanical properties, morphology, and thermal properties of PA6/PA66/GNP composites were investigated. Because the GNP is very expensive, we investigated to use Al2O3 and graphite and examined the characteristics of the prepared composites. Thermal conductivity values of PA6/PA66/GNP composites remarkably increased with increase of GNP contents mainly via layered dispersion in nylon matrix. The thermal conductivity of composite containing 50 wt % of GNP was measured as 5.03 W·m–1·K–1 at 30 °C, indicating an increase of more than 15 times compared with that of the neat PA6. When the Al2O3 was replaced for GNP, the thermal conductivity of composites decreased, but the mechanical properties improved. When graphite was used to replace for GNP, thermal conductivity basically remained unchanged but mechanical properties decreased.

scholarly journals Thermo-mechanical characterization of a bio-composite mortar reinforced with date palm fiber

2020 ◽  
Vol 15 ◽  
pp. 155892502094823
Author(s):  
Samir Benaniba ◽  
Zied Driss ◽  
Mokhtar Djendel ◽  
Elhadj Raouache ◽  
Rabah Boubaaya
Keyword(s):  
Thermal Conductivity ◽  
Composite Material ◽  
Building Materials ◽  
Date Palm ◽  
Mechanical Performance ◽  
Negative Impact ◽  
Natural Fibers ◽  
Palm Fiber ◽  
Date Palm Fibers

Due to respect for the environment and the search for more sustainable materials, scientists have started in recent decades to launch studies on bio-composite materials. It is well known that building materials are among the most commonly used materials and have an obvious negative impact on the environment. The development of environmentally friendly composites as insulating materials in buildings offers practical solutions to reduce energy consumption. Therefore, this work presents the use of a new bio-composite material composed of natural fibers, date palm fibers, cement, and sand. In addition, the study on the effect of adding date palm fibers on the thermo-mechanical characteristics of mortars assesses the thermal insulation properties as well as the water absorption and mechanical performance of this new bio-composite material to use it in the construction of buildings. The percentage by weight of date palm fiber in the test samples varied from 0% to 30% for a fiber size of length equal to 7 mm. The characteristics of these samples were determined experimentally in terms of resistance to bending and compression as well as thermal conductivity. The results show that while increasing the weight of date palm fiber, an obviously reduction in thermal conductivity, flexural, and compressive strength of the composite is observed. Hence, date palm fiber has a positive effect on the thermo-mechanical properties of the composite material. Therefore, it considerably improves the insulating capacity of the mortar.

Increasing the value of a biorefinery based on hot-water extraction: Lignin products

TAPPI Journal ◽  
2012 ◽  
Vol 11 (1) ◽  
pp. 19-26 ◽  
Author(s):  
BILJANA M. BUJANOVIC ◽  
MANGESH J. GOUNDALKAR ◽  
THOMAS E. AMIDON
Keyword(s):  
Carbon Fibers ◽  
Aromatic Compounds ◽  
Low Cost ◽  
Hot Water ◽  
Water Extraction ◽  
Hot Water Extraction ◽  
Isolation And Characterization ◽  
Potential Applications

In conventional pulping technologies, lignin is used mainly as a low-cost source of energy. Small quantities of industrially produced lignin are used for the production of chemicals and materials. Biorefinery technologies are emerging that have an ultimate goal of replacing fossil sources for the production of fuels and other products. To achieve this goal effectively, biorefinery technologies must take advantage of lignin as the most abundant natural aromatic polymer and use it to add higher-value products to product portfolios. Lignin has the potential to be used in making a broad range of high-quality products, including carbon fibers, thermoplastics, and oxygenated aromatic compounds. Existing processes focus primarily on the quality of cellulose and result in a severely modified and contaminated lignin of relatively low value. Lignin produced in more flexible biorefinery operations is more uniform and less contaminated than currently available industrial lignins, opening the door for broader applications of lignin and lignin products. The results of isolation and characterization of lignin dissolved during hot-water extraction and some potential applications of this lignin are discussed.

Raman Spectroscopy of Graphitic Foams

2004 ◽  
Vol 851 ◽  
Author(s):  
Eduardo B. Barros ◽  
Nasser S. Demir ◽  
Antonio G. Souza Filho ◽  
Josué Medes Filho ◽  
Ado Jorio ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Raman Spectroscopy ◽  
National Laboratory ◽  
Weight Ratio ◽  
Spectroscopy Study ◽  
Oak Ridge ◽  
Very High ◽  
Graphitic Foam

ABSTRACTTo better understand the very high thermal conductivity to weight ratio of the graphitic foams recently developed at the Oak Ridge National Laboratory, a Raman spectroscopy study was performed. It was also shown that the Raman scattering can be useful for the characterization of the graphitic foam, being able to evaluate the quality of the samples with respect to the density and location of lattice defects.

Preparation and Characterization of SiC Coating on Graphite Substrate

2014 ◽  
Vol 602-603 ◽  
pp. 412-415 ◽  
Author(s):  
Yan Li Huo ◽  
Shu Guang Chen ◽  
Hai Long Liang ◽  
Chun Peng Wang ◽  
Jian Zhou ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Cross Section ◽  
Vapor Deposition ◽  
Chemical Vapor ◽  
Optical Microscope ◽  
Chemical Vapor Infiltration ◽  
Good Combination ◽  
Graphite Substrate

High thermal conductivity and dense SiC coating were fabricated by chemical vapor deposition (CVD) on surface of different graphite at temperature of 1100°C. The results indicated that the thickness of the coating influences the quality of coating. There was no crack in coating when thickness of the coating is less than 0.3mm. The structure of graphite affected the reaction badly. When the graphite is coarse and porous the reaction is chemical vapor infiltration (CVI) and the interface of coating and substrate isnt obvious. When the graphite is dense and smooth, the coating is covered in surface of graphite, the interface is found between the coating and substrate. Optical microscope and SEM were used to observe the surface and cross-section morphology and microstructure of coatings. It shown coating and substrate had a good combination and the deposited grains mainly showed equiaxed form with the crystallite size of 30 nm at 1100°C.

scholarly journals Characterization of Soil Quality from some Farms of Ghatanji Taluka Region, Dist.Yavatmal (M.S.)

2016 ◽  
Vol 3 (1) ◽  
Author(s):  
R.R. Wankhade
Keyword(s):  
Quality Parameters ◽  
Exchange Capacity ◽  
Free Calcium ◽  
Density Maximum ◽  
Water Capacity ◽  
Physico Chemical ◽  
Maximum Water ◽  
Water Holding

<p>The quality of soil and availability of water are essential factors for the good yield of the crop. Hence it is necessary to analyze some quality parameters of the soil to determine the quality of soil. So in the present study is undertaken to determine the physico-chemical characteristics of some samples of soil from some farms of nearby villages of Ghatanji taluka region, Dist. Yavatmal.The soil characterization was carried out with respect to particle size distribution, bulk density, maximum water holding capacity, available water capacity, hydraulic conductivity, soil pH, electrical conductivity, cation exchange capacity, free calcium carbonate and organic carbon. The important observation during the study was that the parameters were varying for farm to farm of nearby villages. The overall quality of the soil in the study area is good and soil is not getting polluted as there is no industrial waste problem in the region.</p>

Edible Film Coatings to Extend the Shelf-Life of Fresh-Cut Pineapple

2021 ◽  
Vol 885 ◽  
pp. 67-74
Author(s):  
Giuseppina Gullifa ◽  
Stefano Materazzi
Keyword(s):  
Shelf Life ◽  
Complete Characterization ◽  
Coating Material ◽  
Processed Foods ◽  
Minimally Processed ◽  
Film Coatings ◽  
Volatile Organic ◽  
Fresh Cut

This study proposes an innovative coating material and procedure to extend the shelf-life of fresh-cut pineapple classified as “minimally processed foods”. The novelty of this work consists of the using of biodegradable cases for the storage of fruits during the experiments under refrigerated conditions. In addition, the application of the coating process was evaluated over a period of 15 days and a complete characterization of the Volatile Organic Compounds (VOCs) was performed by gaschromatography coupled to mass spectrometry (GC-MS) to assess the effect of the coating material on the flavor, the appearance and the quality of the fruits. Results demonstrated that the application of carboxymethyl cellulose and ascorbic acid on pretreated fresh-cut pineapple is able to reduce the aging process and prolonge the shelf-life of pineapple without requiring conventional PVC cases for storage.

scholarly journals Characterization of Wood and Graphene Nanoplatelets (GNPs) Reinforced Polymer Composites

Materials ◽  
2020 ◽  
Vol 13 (9) ◽  
pp. 2089
Author(s):  
Zainab Al-Maqdasi ◽  
Guan Gong ◽  
Birgitha Nyström ◽  
Nazanin Emami ◽  
Roberts Joffe
Keyword(s):  
Mechanical Properties ◽  
Polymer Composites ◽  
Mechanical Performance ◽  
Wood Fiber ◽  
Graphene Nanoplatelets ◽  
Processing Methods ◽  
Neat Polymer ◽  
Modified Polymer ◽  
Reinforced Polymer

This paper investigates the utilization of commercial masterbatches of graphene nanoplatelets to improve the properties of neat polymer and wood fiber composites manufactured by conventional processing methods. The effect of aspect ratio of the graphene platelets (represented by the different number of layers in the nanoplatelet) on the properties of high-density polyethylene (HDPE) is discussed. The composites were characterized for their mechanical properties (tensile, flexural, impact) and physical characteristics (morphology, crystallization, and thermal stability). The effect of the addition of nanoplatelets on the thermal conductivity and diffusivity of the reinforced polymer with different contents of reinforcement was also investigated. In general, the mechanical performance of the polymer was enhanced at the presence of either of the reinforcements (graphene or wood fiber). The improvement in mechanical properties of the nanocomposite was notable considering that no compatibilizer was used in the manufacturing. The use of a masterbatch can promote utilization of nano-modified polymer composites on an industrial scale without modification of the currently employed processing methods and facilities.

scholarly journals Joining with Reactive Nano-Multilayers: Influence of Thermal Properties of Components on Joint Microstructure and Mechanical Performance

2019 ◽  
Vol 9 (2) ◽  
pp. 262 ◽  
Author(s):  
Bastian Rheingans ◽  
Irina Spies ◽  
Axel Schumacher ◽  
Stephan Knappmann ◽  
Roman Furrer ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Thermal Properties ◽  
Heat Dissipation ◽  
Mechanical Performance ◽  
Local Heat ◽  
Exothermal Reaction ◽  
Excessive Heat ◽  
Component Material ◽  
The Given

Reactive nano-multilayers (RNMLs), which are able to undergo a self-heating exothermal reaction, can, e.g., be utilised as a local heat source for soldering or brazing. Upon joining with RNMLs, the heat produced by the exothermal reaction must be carefully adjusted to the joining system in order to provide sufficient heat for bond formation while avoiding damaging of the joining components by excessive heat. This heat balance strongly depends on the thermal properties of the joining components: a low thermal conductivity leads to heat concentration within the joining zone adjacent to the RNML, while a high thermal conductivity leads to fast heat dissipation into the components. The quality of the joint is thus co-determined by the thermal properties of the joining components. This work provides a systematic study on the influence of the thermal properties upon reactive joining for a set of substrate materials with thermal conductivities ranging from very low to very high. In particular, the evolution of the microstructure within the joining zone as a function of the specific time-temperature-profile for the given component material is investigated, focusing on the interaction between solder, RNML foil and surface metallisations, and the associated formation of intermetallic phases. Finally, the specific microstructure of the joints is related to their mechanical performance upon shear testing, and suggestions for optimum joint design are provided.

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