scholarly journals Experimental Cold-Cured Nanostructured Epoxy-Based Hybrid Formulations: Properties and Durability Performance

Polymers ◽  
2020 ◽  
Vol 12 (2) ◽  
pp. 476 ◽  
Author(s):  
Mariaenrica Frigione ◽  
Mariateresa Lettieri ◽  
Francesca Lionetto ◽  
Leno Mascia
Keyword(s):  
Mechanical Properties ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Thermogravimetric Analysis ◽  
Low Temperature ◽  
Thermal Degradation ◽  
Ambient Temperature ◽  
Durability Performance ◽  
Different Levels

Different hybrid epoxy formulations were produced and cold-cured, monitoring the properties development during low temperature curing and aging. All systems were based on silane functionalized bis-phenol A (DGEBA) resins (Part A), cured at ambient temperature with two amine hardeners (Part B). The different components of the formulations were selected on their potential capability to bring about enhancements in the glass transition temperature. The durability of the produced hybrids was probed in comparison to the corresponding neat epoxies by monitoring changes in glass transition temperature (Tg) and flexural mechanical properties after exposure to different levels of humidity and immersion in water and at temperatures slightly higher than the local ambient temperature, in order to simulate the conditions encountered during summer seasons in very humid environments. The thermal degradation resistance of the hybrid systems was also evaluated by thermogravimetric analysis.

scholarly journals The Mechanical Properties of PVC Nanofiber Mats Obtained by Electrospinning

Fibers ◽  
2021 ◽  
Vol 9 (1) ◽  
pp. 2
Author(s):  
Quoc Pham Le ◽  
Mayya V. Uspenskaya ◽  
Roman O. Olekhnovich ◽  
Mikhail A. Baranov
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Thermogravimetric Analysis ◽  
Thermal Degradation ◽  
Young’S Modulus ◽  
Young's Modulus ◽  
Nanofiber Mats

This paper investigates the mechanical properties of oriented polyvinyl chloride (PVC) nanofiber mats, which, were obtained by electrospinning a PVC solution. PVC was dissolved in a solvent mixture of tetrahydrofuran/dimethylformamide. Electrospinning parameters used in our work were, voltage 20 kV; flow rate 0.5 mL/h; the distance between the syringe tip and collector was 15 cm. The rotating speed of the drum collector was varied from 500 to 2500 rpm with a range of 500 rpm. Nanofiber mats were characterized by scanning electron microscope, thermogravimetric analysis, differential scanning calorimetry methods. The mechanical properties of PVC nanofiber mats, such as tensile strength, Young’s modulus, thermal degradation, and glass transition temperature were also analyzed. It was shown that, by increasing the collector’s rotation speed from 0 (flat plate collector) to 2500 rpm (drum collector), the average diameter of PVC nanofibers decreased from 313 ± 52 to 229 ± 47 nm. At the same time, it was observed that the mechanical properties of the resulting nanofiber mats were improved: tensile strength increased from 2.2 ± 0.2 MPa to 9.1 ± 0.3 MPa, Young’s modulus from 53 ± 14 to 308 ± 19 MPa. Thermogravimetric analysis measurements showed that there was no difference in the process of thermal degradation of nanofiber mats and PVC powders. On the other hand, the glass transition temperature of nanofiber mats and powders did show different values, such values were 77.5 °C and 83.2 °C, respectively.

Development of technology of polysulfone production for 3D printing

2017 ◽  
Vol 29 (6) ◽  
pp. 724-729 ◽  
Author(s):  
Azamat A Zhansitov ◽  
Svetlana Y Khashirova ◽  
Azamat L Slonov ◽  
Zhanna I Kurdanova ◽  
Albert S Shabaev ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
3D Printing ◽  
Thermal Degradation ◽  
Strength Properties ◽  
Cross Linking ◽  
Molten Polymer ◽  
Chain Rigidity

This article discusses the results of experimental research on the synthesis of polyether sulfones and the molten polymer filament layering 3-D printing technology. The regularities of influence of the polycondensation conditions in the synthesis of polyphenylene sulfone on the processes of cross-linking, thermal degradation of the polymer at processing temperatures, and 3-D printing were revealed. It is shown that introduction of cardo fragments increases the glass transition temperature and heat resistance of the copolymers, and the elastic-strength properties, due to the increased chain rigidity. It determined the influence of technological modes of 3-D printing by layering molten polymer filaments on the physico-mechanical properties of polyether sulfones.

scholarly journals Studies on the Modification of Commercial Bisphenol-A-Based Epoxy Resin Using Different Multifunctional Epoxy Systems

2021 ◽  
Vol 2 (2) ◽  
pp. 419-430
Author(s):  
Ankur Bajpai ◽  
James R. Davidson ◽  
Colin Robert
Keyword(s):  
Mechanical Properties ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Bisphenol A ◽  
Epoxy Resin ◽  
Tensile Fracture ◽  
Chemical Structures ◽  
Amino Phenol ◽  
Epoxy Systems

The tensile fracture mechanics and thermo-mechanical properties of mixtures composed of two kinds of epoxy resins of different chemical structures and functional groups were studied. The base resin was a bi-functional epoxy resin based on diglycidyl ether of bisphenol-A (DGEBA) and the other resins were (a) distilled triglycidylether of meta-amino phenol (b) 1, 6–naphthalene di epoxy and (c) fluorene di epoxy. This research shows that a small number of multifunctional epoxy systems, both di- and tri-functional, can significantly increase tensile strength (14%) over neat DGEBA while having no negative impact on other mechanical properties including glass transition temperature and elastic modulus. In fact, when compared to unmodified DGEBA, the tri-functional epoxy shows a slight increase (5%) in glass transition temperature at 10 wt.% concentration. The enhanced crosslinking of DGEBA (90 wt.%)/distilled triglycidylether of meta-amino phenol (10 wt.%) blends may be the possible reason for the improved glass transition. Finally, the influence of strain rate, temperature and moisture were investigated for both the neat DGEBA and the best performing modified system. The neat DGEBA was steadily outperformed by its modified counterpart in every condition.

Effect of reduced graphene oxide on mechanical behavior of an epoxy adhesive in glassy and rubbery states

2021 ◽  
pp. 002199832110316
Author(s):  
Ata Khabaz-Aghdam ◽  
Bashir Behjat ◽  
EAS Marques ◽  
RJC Carbas ◽  
Lucas FM da Silva ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Ambient Temperature ◽  
Mechanical Behavior ◽  
Reduced Graphene Oxide ◽  
Epoxy Adhesive ◽  
Ultimate Strain ◽  
Reduced Graphene

The mechanical behavior of an adhesive, in neat state and reinforced with up to 0.5 wt% of reduced graphene oxide (RGO) was investigated here. Tests were done at temperatures between the ambient temperature and the glass transition temperature ( Tg[Formula: see text] of the adhesive. Using a metal mold, cured plates of the neat and RGO reinforced epoxy adhesive were prepared. The adhesive powder and the bulk dumbbell-shaped specimens, obtained from cured adhesive plates, were subjected to differential scanning calorimetry (DSC) and tensile tests, respectively, to obtain the Tg as well as mechanical properties of the adhesives. The results indicated that adding RGO up to 0.5 wt% increased the glass transition temperature, the modulus of elasticity, and the strength of the adhesive. It was found that the presence of RGO reduced the adhesive’s strain at the break at the ambient temperature. However, at high temperatures, near the Tg, the ultimate strain of RGO-reinforced adhesives decreased slightly when compared to the ultimate strain of the neat specimens. This explains the reduction in toughness at ambient temperature obtained by adding RGO and the increase at high temperatures. Finally, the failure morphology of the neat and RGO-reinforced adhesive specimens was investigated using microscopic imaging of the specimens’ failure cross-sections, which supported and justified the experimental observations.

scholarly journals Synthesis, Properties, and Biodegradability of Thermoplastic Elastomers Made from 2-Methyl-1,3-propanediol, Glutaric Acid and Lactide

Life ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 43
Author(s):  
Lamya Zahir ◽  
Takumitsu Kida ◽  
Ryo Tanaka ◽  
Yuushou Nakayama ◽  
Takeshi Shiono ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Glutaric Acid ◽  
Triblock Copolymers ◽  
Tensile Tests ◽  
Thermoplastic Elastomers ◽  
Proteinase K ◽  
Synthesis Properties

An innovative type of biodegradable thermoplastic elastomers with improved mechanical properties from very common and potentially renewable sources, poly(L-lactide)-b-poly(2-methyl-1,3-propylene glutarate)-b-poly(L-lactide) (PLA-b-PMPG-b-PLA)s, has been developed for the first time. PLA-b-PMPG-b-PLAs were synthesized by polycondensation of 2-methyl-1,3-propanediol and glutaric acid and successive ring-opening polymerization of L-lactide, where PMPG is an amorphous central block with low glass transition temperature and PLA is hard semicrystalline terminal blocks. The copolymers showed glass transition temperature at lower than −40 °C and melting temperature at 130–152 °C. The tensile tests of these copolymers were also performed to evaluate their mechanical properties. The degradation of the copolymers and PMPG by enzymes proteinase K and lipase PS were investigated. Microbial biodegradation in seawater was also performed at 27 °C. The triblock copolymers and PMPG homopolymer were found to show 9–15% biodegradation within 28 days, representing their relatively high biodegradability in seawater. The macromolecular structure of the triblock copolymers of PLA and PMPG can be controlled to tune their mechanical and biodegradation properties, demonstrating their potential use in various applications.

Silane Functionalized Ethylene/Diene Copolymer Modifiers in Composites of Heterophasic Polypropylene and Microsilica

2007 ◽  
Vol 15 (5) ◽  
pp. 343-355 ◽  
Author(s):  
S. Lipponen ◽  
P. Pietikäinen ◽  
U. Vainio ◽  
R. Serimaa ◽  
J.V. Seppälä
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Impact Strength ◽  
Ambient Temperature ◽  
Metallocene Catalyst ◽  
The Poor ◽  
Rubber Toughened ◽  
Rubbery Phase ◽  
The Impact

Ethylene/1,7-octadiene copolymer was polymerised with metallocene catalyst and hydrosilylated to form silane functionalised polyethylenes (PE-co-SiX, X=Cl, OEt, Ph). The functionalised species were tested as modifiers in composites of rubber toughened polypropylene (heterophasic PP, hPP) and microsilica filler (μSi). A metallocene-based functionalised PE (PE-co-SiF) produced earlier in our laboratory and three commercial grades of functionalised polyolefins (one PE- and two PP-based) were used as reference modifiers. Major differences were seen in the toughness of the composites both above and below the glass transition temperature (Tg) of PP. In addition to increasing the stiffness, the microsilica filler enhanced the toughness of the heterophasic polypropylene by over 200% at ambient temperature. Below the Tg of PP (at −20 °C), the influence of μSi was the opposite and the impact strength of the hPP/μSi composite was below that of unfilled hPP. With the addition of just 2 wt% of functionalised polyethylene, the poor cold toughness of hPP/μSi composite was improved by nearly 100%. With the same addition, the toughness of the composites at ambient temperature was improved by 50 to 100% compared with the unfilled hPP. This behaviour was explained by significant changes in the fracture mechanism. Addition of functionalised PE increased the concentration of microsilica in the rubbery phase, allowing the crack to enter that phase. The rubbery phase was also able to absorb a large amount of impact energy below the glass transition temperature of PP.

Plasticization of poly(vinyl butyral) by water: Glass transition temperature and mechanical properties

2018 ◽  
Vol 136 (12) ◽  
pp. 47230 ◽  
Author(s):  
Marlène Desloir ◽  
Cyril Benoit ◽  
Amine Bendaoud ◽  
Pierre Alcouffe ◽  
Christian Carrot
Keyword(s):  
Mechanical Properties ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Water Glass ◽  
Vinyl Butyral
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