scholarly journals Hybrid Composites of Polylactide with Basalt and Carbon Fibers and Their Thermal Treatment

Materials ◽  
2018 ◽  
Vol 12 (1) ◽  
pp. 95 ◽  
Author(s):  
Stanisław Kuciel ◽  
Paulina Romańska
Keyword(s):  
Water Absorption ◽  
Elevated Temperatures ◽  
Hybrid Composites ◽  
Tensile Tests ◽  
Equal Mass ◽  
Degree Of Crystallinity ◽  
Stress Concentrations ◽  
Scanning Calorimetry ◽  
Heat Treated ◽  
The Matrix

In this research, polylactide was hybrid-reinforced and heat-treated in order to obtain durable structural materials with the use of eco-friendly components. Differential scanning calorimetry (DSC) analysis, tensile tests at various temperatures, Vicat tests, impact tests, and microscopic observations were conducted on the annealed and non-heat-treated specimens. The theoretical and true density, as well as water absorption, were also determined. The simultaneous introduction of chopped carbon and basalt fibers in equal mass fractions of 7.5% and 12.5% resulted in satisfactory increases in stiffness and tensile strength. The reinforcing effect was more efficient for the heat-treated composites, especially at elevated temperatures. Heat treatment significantly increased the degree of crystallinity of the matrix, improving heat resistance and reducing water absorption. It also reduced the stress concentrations in the injection-molded specimens.

Enhancing the Thermal and Mechanical Characteristics of Polyvinyl Alcohol (PVA)-Hemp Protein Particles (HPP) Composites

2021 ◽  
Vol 36 (2) ◽  
pp. 137-143
Author(s):  
S. A. Awad
Keyword(s):  
Mechanical Properties ◽  
Elevated Temperatures ◽  
Composite Films ◽  
Tensile Tests ◽  
Mechanical Analysis ◽  
Decomposition Temperature ◽  
Scanning Calorimetry ◽  
Solution Casting Method ◽  
Protein Particles

Abstract This paper aims to describe the thermal, mechanical, and surface properties of a PVA/HPP blend whereby the film was prepared using a solution casting method. The improvements in thermal and mechanical properties of HPP-based PVA composites were investigated. The characterization of pure PVA and PVA composite films included tensile tests, thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). The results of TGA and DSC indicated that the addition of HPP increased the thermal decomposition temperature of the composites. Mechanical properties are significantly improved in PVA/HPP composites. The thermal stability of the PVA composite increased with the increase of HPP filler content. The tensile strength increased from 15.74 ± 0.72 MPa to 27.54 ± 0.45 MPa and the Young’s modulus increased from 282.51 ± 20.56 MPa to 988.69 ± 42.64 MPa for the 12 wt% HPP doped sample. Dynamic mechanical analysis (DMA) revealed that at elevated temperatures, enhanced mechanical properties because of the presence of HPP was even more noticeable. Morphological observations displayed no signs of agglomeration of HPP fillers even in composites with high HPP loading.

scholarly journals Mechanical and Thermal Characterization of Natural Intralaminar Hybrid Composites Based on Sisal

Polymers ◽  
2020 ◽  
Vol 12 (4) ◽  
pp. 866 ◽  
Author(s):  
Alexandre L. Pereira ◽  
Mariana D. Banea ◽  
Jorge S.S. Neto ◽  
Daniel K.K. Cavalcanti
Keyword(s):  
Thermal Properties ◽  
Natural Fiber ◽  
Hybrid Composites ◽  
Thermal Characterization ◽  
Mechanical And Thermal Properties ◽  
Scanning Calorimetry ◽  
Sem Images ◽  
The Matrix ◽  
American Society ◽  
Curaua Fibers

The main objective of this work was to investigate the effect of hybridization on the mechanical and thermal properties of intralaminar natural fiber-reinforced hybrid composites based on sisal. Ramie, sisal and curauá fibers were selected as natural fiber reinforcements for the epoxy matrix based composites, which were produced by the hand lay-up technique. Tensile, flexural and impact tests were carried out according to American society for testing and materials (ASTM) standards to characterize the hybrid composites, while differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) were used to evaluate the thermal properties. It was found that the mechanical properties are improved by hybridization of sisal based composites. The thermal analysis showed that the hybridization did not significantly affect the thermal stability of the composites. A scanning electron microscopy (SEM) was used to examine the fracture surface of the tested specimens. The SEM images showed a brittle fracture of the matrix and fiber breakage near the matrix.

scholarly journals Performance of Thermo-Mechanically Processed AA7075 Alloy at Elevated Temperatures—From Microstructure to Mechanical Properties

Metals ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 884 ◽  
Author(s):  
Seyed Vahid Sajadifar ◽  
Emad Scharifi ◽  
Ursula Weidig ◽  
Kurt Steinhoff ◽  
Thomas Niendorf
Keyword(s):  
Mechanical Properties ◽  
Elevated Temperatures ◽  
Tensile Tests ◽  
Uniaxial Tensile ◽  
Forming Process ◽  
Softening Mechanism ◽  
Rate Dependent ◽  
Heat Treated ◽  
Different Temperatures ◽  
Die Forming

This study focuses on the high temperature characteristics of thermo-mechanically processed AA7075 alloy. An integrated die forming process that combines solution heat treatment and hot forming at different temperatures was employed to process the AA7075 alloy. Low die temperature resulted in the fabrication of parts with higher strength, similar to that of T6 condition, while forming this alloy in the hot die led to the fabrication of more ductile parts. Isothermal uniaxial tensile tests in the temperature range of 200–400 °C and at strain rates ranging from 0.001–0.1 s−1 were performed on the as-received material, and on both the solution heat-treated and the thermo-mechanically processed parts to explore the impacts of deformation parameters on the mechanical behavior at elevated temperatures. Flow stress levels of AA7075 alloy in all processing states were shown to be strongly temperature- and strain-rate dependent. Results imply that thermo-mechanical parameters are very influential on the mechanical properties of the AA7075 alloy formed at elevated temperatures. Microstructural studies were conducted by utilizing optical microscopy and a scanning electron microscope to reveal the dominant softening mechanism and the level of grain growth at elevated temperatures.

scholarly journals Mechanical, Thermal and Microstructural Characteristic of 3D Printed Polylactide Composites with Natural Fibers: Wood, Bamboo and Cork

2021 ◽  
Author(s):  
Karolina E. Mazur ◽  
Aleksandra Borucka ◽  
Paulina Kaczor ◽  
Szymon Gądek ◽  
Rafał Bogucki ◽  
...  
Keyword(s):  
Fused Deposition Modeling ◽  
Elevated Temperatures ◽  
Fiber Type ◽  
Mechanical Tests ◽  
Degree Of Crystallinity ◽  
Scanning Calorimetry ◽  
Fused Deposition ◽  
The Impact ◽  
Different Levels ◽  
Natural Fillers

AbstractIn the study, polylactide-based (PLA) composites modified with natural particles (wood, bamboo, and cork) and with different levels of infilling (100%, 80%, and 60%) obtained by fused deposition modeling were tested. The effect of fiber type, infill level and crystallization rate on the mechanical properties were investigated by using tensile, flexural, and impact tests. The materials were subjected to mechanical tests carried out at 23 and 80 °C. Differential scanning calorimetry were employed to analyze crystallization behavior of composite. Furthermore, hydrothermal degradation was performed, and its effect on the properties was analyzed. The addition of natural fillers and different levels of infilling result in a similar level of reduction in the properties. However, the addition of natural fillers resulted in a slightly lower drop than the lowered infilling rate − 40% and 50% for tensile strength, respectively. Moreover, it was found that, composites made of PLA are more sensitive to high temperatures than to water. The decrease in Young's modulus of PLA at 80 °C was 90%, while after 28 days of hydrodegradation ~ 9%. The addition of fibers reduced this decrease at elevated temperatures. Importantly, in the case of a brittle material such as PLA, the impact strength has been improved by 50% for composites with cork particles and other lignocellulosic composites remained at the same level as for resin. Generally, the thermal treatment of composites increased the degree of crystallinity of the materials, as reflected in the higher results of mechanical tests.

scholarly journals Influence of the Lignin Content on the Properties of Poly(Lactic Acid)/lignin-Containing Cellulose Nanofibrils Composite Films

Polymers ◽  
2018 ◽  
Vol 10 (9) ◽  
pp. 1013 ◽  
Author(s):  
Xuan Wang ◽  
Yuan Jia ◽  
Zhen Liu ◽  
Jiaojiao Miao
Keyword(s):  
Lactic Acid ◽  
Lignin Content ◽  
Cellulose Nanofibrils ◽  
Composite Films ◽  
Tensile Tests ◽  
Nucleating Agent ◽  
Mechanical Analysis ◽  
Degree Of Crystallinity ◽  
Poly Lactic Acid ◽  
Scanning Calorimetry

Poly(lactic acid) (PLA)/lignin-containing cellulose nanofibrils (L-CNFs) composite films with different lignin contents were produced bythe solution casting method. The effect of the lignin content on the mechanical, thermal, and crystallinity properties, and PLA/LCNFs interfacial adhesion wereinvestigated by tensile tests, thermogravimetric analysis, differential scanning calorimetry (DSC), dynamic mechanical analysis, Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). The tensile strength and modulus of the PLA/9-LCNFs (9 wt % lignin LCNFs) composites are 37% and 61% higher than those of pure PLA, respectively. The glass transition temperature (Tg) decreases from 61.2 for pure PLA to 52.6 °C for the PLA/14-LCNFs (14 wt % lignin LCNFs) composite, and the composites have higher thermal stability below 380 °C than pure PLA. The DSC results indicate that the LCNFs, containing different lignin contents, act as a nucleating agent to increase the degree of crystallinity of PLA. The effect of the LCNFs lignin content on the PLA/LCNFs compatibility/adhesion was confirmed by the FTIR, SEM, and Tg results. Increasing the LCNFs lignin content increases the storage modulus of the PLA/LCNFs composites to a maximum for the PLA/9-LCNFs composite. This study shows that the lignin content has a considerable effect on the strength and flexibility of PLA/LCNFs composites.

scholarly journals Effect of addition of different reinforcements on the microstructure and mechanical characterization of the Al-Flyash composites

2021 ◽  
Vol 15 (56) ◽  
pp. 217-228
Author(s):  
Milind K. Wasekar ◽  
Mohan P. Khond
Keyword(s):  
Tensile Strength ◽  
Hybrid Composites ◽  
Tensile Tests ◽  
Stir Casting ◽  
Interface Bonding ◽  
Casting Technique ◽  
Testing Procedures ◽  
The Matrix ◽  
Aluminum 6061 Alloy

The aim of this work is to investigate the influence of the addition of silicon carbide and molybdenum disulfide on the microstructure and the tensile strength of the Al-Flyash hybrid composites prepared using the stir casting technique. The composite with aluminum 6061 alloy as the matrix and flyash as the reinforcement, with different weight fractions, is investigated to study its microstructure and the tensile strength. The same has been compared with the hybrid composites with Aluminum-Flyash/SiC and Aluminum-Flyash/MoS2 for different weight fractions of the reinforcements. The tensile tests were conducted as per ASTM standard testing procedures at room temperature. From the results it is identified that tensile strength of the Al6061-Flyash composite is lesser than the Al6061-Flyash/SiC and Al6061-Flyash/MoS2 hybrid composites. It is also observed that increment in the composition of the SiC and MoS2 causes the increment in the tensile strength of the hybrid composite. This increment in the tensile strength is due to good interface bonding and uniform distribution of the reinforcements in the composite.

scholarly journals Effect of Minor Amount of Sc on the Thermomechanical Treatment of Al-Zn-Mg-Cu-Zr Alloy

2021 ◽  
Author(s):  
Azam Beigi Kheradmand ◽  
Shamseddin Mirdamadi ◽  
Zahra Lalegani
Keyword(s):  
Thermomechanical Treatment ◽  
Volume Fraction ◽  
Cast Alloy ◽  
Tensile Tests ◽  
Minor Amount ◽  
Microstructural Investigation ◽  
Software Analysis ◽  
Heat Treated ◽  
The Matrix ◽  
Mechanical And Microstructural Properties

Abstract In this study, mechanical and microstructural properties of Al-Zn-Mg-Cu-Zr cast alloy with 0.1% Sc under homogeneous, dissolution, and T6 and thermomechanical treatments with the aim of increasing the volume fraction of MgZn2 and Al3(Sc,Zr) reinforcing sediments were examined by hardness, microscopic examinations and tensile tests and software analysis. The results showed that firstly, the hardness results are well proportional to the results of tensile properties of alloys and secondly, the strength of the alloy with thermomechanical treatments compared to T6 treatments increased from 492 MPa to 620 MPa and the elongation increased from 8% to 17% and 100 % upgraded. Microstructural investigation and fracture cross section showed that Al3(Sc,Zr) nanoparticles were evenly distributed among MgZn2 particles and the alloy fracture was of semi-ductile type and in the fracture section nanoparticles less than 10 nm were observed at the end of the dimples. Also, the volume fraction of nanoparticles in the whole microstructure of thermomechanical treatment samples was much higher than that of T6 heat treated samples, so that the percentage of Al3(Sc,Zr) sediments from less than 1% in T6 operation to 8.28% in quench-controlled thermomechanical operation (with 50% deformation) has arrived. QI index in thermomechanical treatment samples is 19% higher than T6 samples, so that this index has increased from 641 in T6 operation to 760 in samples under thermomechanical treatment due to sediment morphology, volume fraction of sediments, their uniform distribution in the matrix, and nano sized sediments in samples under thermomechanical treatment.

Characterization of cellulose nanocrystals extracted from El Diss and El Retma local plants and their dispersion in poly(vinyl alcohol-co-ethylene) matrix in the presence of borax

2020 ◽  
pp. 096739112091087
Author(s):  
Lilia Benchikh ◽  
Abdelhafid Merzouki ◽  
Yves Grohens ◽  
Melia Guessoum ◽  
Isabelle Pillin
Keyword(s):  
Water Absorption ◽  
North Africa ◽  
Cellulose Nanocrystals ◽  
Vinyl Alcohol ◽  
Poly Vinyl Alcohol ◽  
Scanning Calorimetry ◽  
The Matrix ◽  
Dsc Analyses ◽  
Local Plants

This study aims to investigate the potential of two local fibers, namely El Diss and El Retma, which are abundant in the mountains of North Africa (Sétif, Algeria), to provide cellulose nanocrystals (CNCs). Then, the isolated CNCs from El Diss were used as a reinforcement for a poly(vinyl alcohol-co-ethylene) matrix (EVOH) in the absence and in the presence of borax which was added to improve the interactions between the CNCs and the matrix. The extracted CNCs from both El Diss (CNCD) and El Retma (CNCR) were characterized by Zeta-sizer analysis using dynamic light scattering (DLS), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and scanning electronic microscopy. Also, untreated EVOH/CNCD nanocomposites and borax-treated EVOH/CNCD/BOR have been characterized using FTIR, differential scanning calorimetry (DSC) analyses, and by the study of their water absorption behavior. The DLS analysis provided the transversal length of the particles and showed that the surface of the obtained CNCs is negatively charged due to the presence of sulfated ions. Also, FTIR results confirmed the elimination of extra cellulosic substances, whereas TGA proved that the degradation of CNCs occurs at relatively lower temperatures compared with the neat fibers. The incorporation of borax to EVOH/CNCD nanocomposites showed its efficiency in improving the interactions at the interface between EVOH and the CNCD, which significantly affected the material’s thermal properties as concluded from DSC results and their water absorption behavior.

scholarly journals Influence of Myrrh Extracts on the Properties of PLA Films and Melt-Spun Multifilament Yarns

Materials ◽  
2020 ◽  
Vol 13 (17) ◽  
pp. 3824
Author(s):  
Evaldas Bolskis ◽  
Erika Adomavičiūtė ◽  
Egidijus Griškonis ◽  
Valdas Norvydas
Keyword(s):  
Optical Properties ◽  
Ethanolic Extract ◽  
Tensile Tests ◽  
Degree Of Crystallinity ◽  
Scanning Calorimetry ◽  
Melt Spun ◽  
Spun Yarns ◽  
Degree Of Crystallization ◽  
Multifilament Yarns ◽  
Antibacterial And Antifungal

A possible approach for providing new properties for textiles is the insertion of natural ingredients into the textile product during the process of its manufacture. Myrrh has long been used in medicine as an antibacterial and antifungal material. Polylactide (PLA) is a thermoplastic synthetic biopolymer obtained from renewable resources—and due its biodegradability, is also widely used in medicine. In this study, films and multifilament yarns from modified biodegradable PLA granules with ethanolic and aqueous myrrh extracts were developed and characterized. Optical microscopy was used to determine the surface morphology of PLA/myrrh multifilament yarns. Tensile tests, ultraviolet-visible (UV-vis), differential scanning calorimetry (DSC) were applied to determine, consequently, mechanical, optical properties and degree of crystallinity of PLA/myrrh films and multifilament yarns. The chemical composition of PLA/myrrh multifilament yarns was estimated by Fourier-transform infrared (FTIR) spectroscopy method. The results showed that it is possible to form PLA melt-spun multifilament yarns with myrrh extract. The type of myrrh extract (ethanolic or aqueous) has a significant influence on the mechanical and optical properties of the PLA films and melt-spun yarns. The mechanical properties of PLA films and melt-spun multifilament yarns formed from PLA granules with aqueous myrrh extract decreased 19% and 21% more than PLA with ethanolic extract, respectively. Analysis of UV-vis spectra showed that, due to the yellow hue, the reflectance of PLA films and melt-spun PLA multifilament yarns modified with myrrh extracts decreased exponentially. The DSC test showed that multifilament yarns from PLA modified with aqueous extract had the highest degree of crystallization.

scholarly journals Maleated polypropylene as coupling agent for polypropylene composites reinforced with Eucalyptus and Pinus particles

BioResources ◽  
2019 ◽  
Vol 14 (2) ◽  
pp. 4774-4791
Keyword(s):  
Degree Of Crystallinity ◽  
Esterification Reaction ◽  
Scanning Electron Micrographs ◽  
Scanning Calorimetry ◽  
Polypropylene Composites ◽  
Maleated Polypropylene ◽  
The Matrix ◽  
Twin Screw ◽  
Coniferous Wood ◽  
Scanning Electron

Waste from the processing of hardwood and coniferous wood generated in the timber industries is difficult to dispose of and can cause considerable environmental impacts, such as soil and groundwater contamination. In this context, composites with varying concentrations of polypropylene, maleated polypropylene, and particulate Eucalyptus and Pinus waste were produced in a twin screw extruder and injection molded as test bodies for tensile and flexural tests. The morphology of the composites was investigated via scanning electron microscopy. The thermal properties were identified through differential scanning calorimetry. The tensile and flexural results for the two waste formulations indicated that the addition of vegetable fillers increased the modulus of elasticity and bending, and the compatibilizer provided increased resistance to stress and maximum deflection. The scanning electron micrographs illustrated the wetting of the cellulosic charge by the thermoplastic polymer with the compatibilizer, which corroborated the possible occurrence of an esterification reaction and hydrogen bonding interactions in the matrix-particle interface. The incorporation of waste in the composite resulted in the reduction of the degree of crystallinity of polypropylene, regardless of the use of the compatibilizer. This was explained by the barrier capacity of the charge, which prevented the growth of the crystals.

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