scholarly journals Protection of Flax/PLLA Biocomposites from Seawater Ageing by External Layers of PLLA

2011 ◽  
Vol 2011 ◽  
pp. 1-8 ◽  
Author(s):  
A. Le Duigou ◽  
J. M. Deux ◽  
P. Davies ◽  
C. Baley
Keyword(s):  
Mechanical Properties ◽  
Thermal Analysis ◽  
Weight Gain ◽  
Microscopic Examination ◽  
Large Drop ◽  
Damage Mechanisms ◽  
Protection Property ◽  
Wet Ageing ◽  
Property Changes

Biocomposites are sensitive to water, and previous work on flax reinforced PLLA showed a large drop in mechanical properties after immersion (Le Duigou et al. 2009). Unreinforced PLLA was much less sensitive. This paper presents a strategy to reduce the influence of wet ageing by adding extra layers of PLLA on the biocomposite surface. Weight gain measurements show that a PLLA coating 350 m thick reduces weight gain by half, and biocomposite stiffness and strength after ageing are improved by 100% compared to uncoated composite behaviour. Thermal analysis and microscopic examination are used to show damage mechanisms with and without protection. Property changes are shown to be quasilinearly related to weight gain.

scholarly journals The Potential for Natural Stones from Northeastern Brazil to Be Used in Civil Construction

Minerals ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 440
Author(s):  
Fabiana Pereira da Costa ◽  
Jucielle Veras Fernandes ◽  
Luiz Ronaldo Lisboa de Melo ◽  
Alisson Mendes Rodrigues ◽  
Romualdo Rodrigues Menezes ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Thermal Analysis ◽  
Differential Thermal Analysis ◽  
Chemical Resistance ◽  
Mechanical Analysis ◽  
Northeastern Brazil ◽  
X Ray Diffraction ◽  
X Ray ◽  
Chemical Agents ◽  
Natural Stones

Natural stones (limestones, granites, and marble) from mines located in northeastern Brazil were investigated to discover their potential for use in civil construction. The natural stones were characterized by chemical analysis, X-ray diffraction, differential thermal analysis, and optical microscopy. The physical-mechanical properties (apparent density, porosity, water absorption, compressive and flexural strength, impact, and abrasion) and chemical resistance properties were also evaluated. The results of the physical-mechanical analysis indicated that the natural stones investigated have the potential to be used in different environments (interior, exterior), taking into account factors such as people’s circulation and exposure to chemical agents.

Annealing Effects on Mechanical Properties and Microstructure of AZ31 Alloy Sheet Differential-Speed-Rolled at Low Temperatures

2007 ◽  
Vol 558-559 ◽  
pp. 213-216 ◽  
Author(s):  
Y.G. Jeong ◽  
Woo Jin Kim ◽  
Seo Gou Choi ◽  
Ha Guk Jeong
Keyword(s):  
Mechanical Properties ◽  
Tensile Elongation ◽  
Az31 Alloy ◽  
Alloy Sheet ◽  
Large Drop ◽  
High Anisotropy ◽  
Texture Change ◽  
Annealing Effects ◽  
Anisotropy Of Mechanical Properties ◽  
Differential Speed

For the Magnesium alloy AZ31, hot rolling is usually carried out in the temperature range between 250 and 400°C but the processed sheets usually exhibit high anisotropy in mechanical properties. In the current study, DSR process was found to be effective in improving anisotropy of mechanical properties and ductility at room temperature. Full recrystallization takes place from 200°C and above. A large drop of UTS occurs above 200°C where full recrystallization starts. Tensile elongation increases with annealing temperature but anisotropy degrades from 200°C onwards. Texture change during recrystallization is believed to be responsible for this result.

Mechanical Properties, Electrical Conductivity and Differential Thermal Analysis of Lithium Sulphate with Small Quantities of Potassium Sulphate

1967 ◽  
Vol 22 (8) ◽  
pp. 1177-1180 ◽  
Author(s):  
Bengt Augustsson ◽  
Arnold Kvist
Keyword(s):  
Mechanical Properties ◽  
Thermal Analysis ◽  
Phase Diagram ◽  
Electrical Conductivity ◽  
Differential Thermal Analysis ◽  
Potassium Sulphate ◽  
Lithium Sulphate ◽  
New Phase

Previously obtained conductivity and viscosity results for the system (Li,K)2SO4 with less than 3 mole% K2SO4 show bad agreement with the phase diagram given in the literature. From conductivity, viscosity and differential thermal analysis we have constructed a new phase diagram for these concentrations.

scholarly journals Effect of Water on Some Mechanical Properties for Sawdust and Chopped Reeds /UPE composites

2011 ◽  
Vol 8 (2) ◽  
pp. 551-560
Author(s):  
Baghdad Science Journal
Keyword(s):  
Mechanical Properties ◽  
Weight Gain ◽  
Flexural Strength ◽  
Young’S Modulus ◽  
Polyester Resin ◽  
Young's Modulus ◽  
Unsaturated Polyester ◽  
Molding Method ◽  
Effect Of Water ◽  
Composite Samples

In this study, composite materials were prepared using unsaturated polyester resin as binder with two types of fillers (sawdust and chopped reeds). The molding method is used to prepare sheets of UPE / sawdust composite and UPE / chopped reeds composite. The mechanical properties were studied including flexural strength and Young's modulus for the samples at normal conditions (N.C). The Commercial wood, UPE and its composite samples were immersed in water for about 30 days to find the weight gain (Mt%) of water for the samples, also to find the effect of water on their flexural strength and Young's modulus. The results showed that the samples of UPE / chopped reeds composite gained highest values of flexural strength (24.5 MPa) and Young's modulus (5.1 GPa) as compared with other composites at (N.C). The results showed that the wet samples of sawdust composite have lowest values of weight gain (Mt %) of water (0.043%) as compared with other composites after immersion. Also it’s showed a slight decrease in values of Young's modulus for all the samples after immersion as compared with the samples at (N.C). Finally it’s showed a slight decrease in values of flexural strength for all the samples except for the composite material formed from UPE / chopped reeds which showed an increase in the value of flexural strength after immersion, where the wet samples of UPE / chopped reeds composite gained (29 MPa) as compared with the samples at (N.C).

scholarly journals Development of a New ATD-P Tester for Hard Wear Resistant Materials

2017 ◽  
Vol 17 (1) ◽  
pp. 37-40 ◽  
Author(s):  
M. Dojka ◽  
R. Dojka ◽  
A. Studnicki
Keyword(s):  
Mechanical Properties ◽  
Thermal Analysis ◽  
Cast Iron ◽  
Computer Simulations ◽  
Silica Sand ◽  
Wear Resistant ◽  
Chromium Cast Iron

Abstract The aim of presented studies was to develop a new geometry of the overflow part of standard ATD-C tester for derivative thermal analysis in a way that it would allow to obtain samples for abrasion and mechanical properties tests in the same mould without the need of cutting them from a block of material. The pattern of new ATD-P tester has parts reflecting implemented samples. Computer simulations regarding initial verification of new tester were performed in NovaFlow software. Chromium cast iron melts were made for testing the sampler in real conditions and TDA analysis for casting material were conducted. The sandmix was prepared on silica sand matrix per the ALPHASET technology. This new solution greatly simplifies the preparations of materials difficult to machine.

Correlation between Physico-Mechanical Properties of NR-BR Blends in Tire Tread Formulation with their Thermal Behaviors

2008 ◽  
Vol 81 (2) ◽  
pp. 297-317 ◽  
Author(s):  
Saeed Taghvaei-Ganjali ◽  
Fereshteh Motiee ◽  
Farsa Fotoohi
Keyword(s):  
Mechanical Properties ◽  
Thermal Analysis ◽  
Peak Height ◽  
Peak Height Ratio ◽  
Butadiene Rubber ◽  
Height Ratio ◽  
Thermal Behaviors ◽  
Degradation Temperature ◽  
Rubber Compounds ◽  
Successful Technique

Abstract Thermal analysis provides a successful technique for the characterization and identification of rubber compounds. In this study, TGA (thermogravimetric analysis) and DTG (TGA derivative) profiles are used to predict and define the physico-mechanical properties of natural rubber — butadiene rubber (NR / BR) blends, using their thermal behaviors. DTG curves of vulcanizate showed that the initial degradation temperature of NR is lower than BR. According to TGA-DTG profiles we have demonstrated two useful factors, ΔTmax (Tmax BR100−Tmax BRX) and peak height ratio of NR-BR blends which are correlated with physico-mechanical properties of blends.

Influence of Polyacrylate on the Compatibility in P(MMA/EA)/PU Semi-IPNs

2012 ◽  
Vol 627 ◽  
pp. 873-877
Author(s):  
Xiao Xia Jian ◽  
Le Qin Xiao ◽  
Wei Liang Zhou ◽  
Hai Qin Ding
Keyword(s):  
Mechanical Properties ◽  
Thermal Analysis ◽  
Polymer Networks ◽  
Thermoplastic Elastomer ◽  
Ethyl Acrylate ◽  
Interpenetrating Polymer Networks ◽  
Structure And Properties ◽  
Infrared Spectrometer ◽  
Nuclear Magnetic Resonance Spectrometry ◽  
Magnetic Resonance Spectrometry

The Semi-Interpenetrating Polymer Networks(Semi-IPNs) of poly(methyl methyacrylate/ethyl acrylate)(P(MMA/EA)) and polyurethane thermoplastic elastomer (PU) were synthesized by PU and copolymer of methyl methacrylate and ethyl acrylate to improve the compatibility of polymethyl methacrylate(PMMA) and PU Semi-IPNs . The structure and properties were investigated by Fourier transform infrared spectrometer, Solid nuclear magnetic resonance spectrometry, Dynamic mechanical thermal analysis and Mechanical properties. The tensile stress of (P(MMA/EA)/PU)( P(MMA/EA):PU=3:7) can get to 9.6MPa, the additional physical crosslinks and entanglement for Semi-IPNs are the reasons.

Influence of process conditions on hygroscopicity and mechanical properties of European beech thermally modified in a high-pressure reactor system

Holzforschung ◽  
2016 ◽  
Vol 70 (10) ◽  
pp. 971-979 ◽  
Author(s):  
Michael Altgen ◽  
Holger Militz
Keyword(s):  
Mechanical Properties ◽  
Cell Wall ◽  
European Beech ◽  
Wood Properties ◽  
Reactor System ◽  
Bending Test ◽  
Process Conditions ◽  
Dynamic Vapor Sorption ◽  
Property Changes ◽  
Closed Reactor

Abstract European beech (Fagus sylvatica L.) was thermally modified in a closed reactor system under various process conditions. Sorption cycles, dynamic vapor sorption (DVS) measurements, and a three-point bending test were performed on thermally modified wood (TMW) to assess hygroscopicity and mechanical properties. As a function of mass loss (ML), the initial equilibrium moisture content (EMC) measured at 20°C/65% relative humidity (RH) directly after the process was strongly influenced by the RH during the process. This effect is explained by realignments of amorphous polymers in the cell wall ultra-structure in the course of thermal modification (TM). However, the EMC of TMW gradually increased after sorption cycles consisting of conditioning over liquid water and water-soaking. This increase was most distinct for TMW modified at low RH, which is an indication for reversible ultra-structural realignments. Results of the bending test suggest that structural realignments also hindered the plastic flow of amorphous cell wall polymers, thereby reducing inelastic toughness and inelastic deflection, while other bending properties were solely affected by ML alone. Process conditions in a closed reactor systems have a profound impact on resulting wood properties, and thus, the partial reversibility of these property changes need to be considered during the application.

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