scholarly journals Interface Characterization of Epoxy Resin Nanocomposites: A Molecular Dynamics Approach

Fibers ◽  
2018 ◽  
Vol 6 (3) ◽  
pp. 54 ◽  
Author(s):  
Carlos Sáenz Ezquerro ◽  
Manuel Laspalas ◽  
Agustín Chiminelli ◽  
Francisco Serrano ◽  
Clara Valero
Keyword(s):  
Molecular Dynamics ◽  
Epoxy Resin ◽  
Polymer Nanocomposites ◽  
Materials Science ◽  
General Rule ◽  
Diglycidyl Ether ◽  
Interface Region ◽  
Cross Linking ◽  
Interface Thickness ◽  
Epoxy Resin Nanocomposites

In polymer nanocomposites, the interface region between the matrix and the fillers has been identified as a key interaction region that strongly determines the properties of the final material. Determining its structure is crucial from several points of view, from modeling (i.e., properties prediction) to materials science (i.e., understanding properties/structure relationships). In the presented paper, a method for characterizing the interface region of polymer nanocomposites is described using molecular dynamics (MD) simulations. In particular, the structure of the polymer within the interface region together with its dimension in terms of thickness were analyzed through density profiles. Epoxy resin nanocomposites based on diglycidyl ether of bisphenol A (DGEBA) were studied using this approach, and the interface region with triple walled carbon nanotubes (TWCNT) and carbon fibers (CF) was characterized. The effect of carbon nanotube diameter, type of hardener, and effect of epoxy resin cross-linking degree on interface thickness were analyzed using MD models. From this analysis no general rule on the effect of these parameters on the interface thickness could be established, since in some cases overlapping effects between the analyzed parameters were observed, and each specific case needs to be analyzed independently in detail. Results show that the diameter has an impact on interface thickness, but this effect is affected by the cross-linking degree of the epoxy resin. The type of hardener also has a certain influence on the interface thickness.

Influence of Carbon Nanotube Aspect Ratio on Glass Transition Temperature of Polymers: A Molecular Dynamics Simulation Study

2015 ◽  
Vol 817 ◽  
pp. 797-802 ◽  
Author(s):  
Cai Jiang ◽  
Jian Wei Zhang ◽  
Shao Feng Lin ◽  
Su Ju ◽  
Da Zhi Jiang
Keyword(s):  
Molecular Dynamics ◽  
Glass Transition ◽  
Carbon Nanotube ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Aspect Ratio ◽  
Epoxy Resin ◽  
Md Simulations ◽  
Diglycidyl Ether ◽  
Dynamics Simulation

Molecular dynamics (MD) simulations on three single walled carbon nanotube (SWCNT) reinforced epoxy resin composites were conducted to study the influence of SWCNT type on the glass transition temperature (Tg) of the composites. The composite matrix is cross-linked epoxy resin based on the epoxy monomers bisphenol A diglycidyl ether (DGEBA) cured by diaminodiphenylmethane (DDM). MD simulations of NPT (constant number of particles, constant pressure and constant temperature) dynamics were carried out to obtain density as a function of temperature for each composite system. The Tg was determined as the temperature corresponding to the discontinuity of plot slopes of the densityvsthe temperature. In order to understand the motion of polymer chain segments above and below the Tg, various energy components and the MSD at various temperatures of the composites were investigated and their roles played in the glass transition process were analyzed. The results show that the Tg of the composites increases with increasing aspect ratio of the embedded SWCNT

scholarly journals Experimental Study on the Surface Properties of Nanoalumina-Filled Epoxy Resin Nanocomposites

2020 ◽  
Vol 10 (3) ◽  
pp. 733 ◽  
Author(s):  
Pinto ◽  
Amaro ◽  
Bernardo
Keyword(s):  
Experimental Study ◽  
Surface Roughness ◽  
Epoxy Resin ◽  
Surface Properties ◽  
Weight Fraction ◽  
Maximum Size ◽  
Contact Angles ◽  
Diglycidyl Ether ◽  
Alumina Nanoparticles ◽  
Epoxy Resin Nanocomposites

This article presents an experimental study on the surface properties of epoxy resin nanocomposites (EPNCs) manufactured with a thermosetting epoxy resin (EP)–bisphenol A diglycidyl ether (BADGE)–2-[[4-[2-[4-(Oxiran-2-ylmethoxy)phenyl]propan-2-yl]phenoxy]methyl]oxirane) and filled with alumina nanoparticles (NPs). The NPs consist of pretreated (with a silane agent) alpha alumina with irregular shapes and a 100 nm maximum size. Three weight fractions of NPs were studied: 1, 3, and 5 wt. (%). Two different epoxy (EP) resins were manufactured, one cured and postcured with bis (4-aminophenyl) methane (DDM); and another one cured with 3-dodec-2-enyloxolane-2,5-dione (DDSA) + 8-methyl-3a,4,7,7a-tetrahydro-4,7-methano-2-benzofuran-1,3-dione (MNA). The wettability and the surface roughness of the obtained EPNCs were studied through the measurement of contact angles and topographic images obtained with atomic force microscopy (AFM), respectively. Significant influence of both the loading of NPs and used curing agents was observed. EPNCs cured with DDM were shown to be hydrophobic for 0, 1, and 3 wt. (%) and hydrophilic for 5 wt. (%). Maximum surface roughness was observed for 5 wt. (%). EPNCs cured with DDSA+MNA were shown to be hydrophilic for 0 and 1 wt. (%) and hydrophobic for 3 and 5 wt. (%). The surface roughness decreased as the weight fraction of NPs increased until 3 wt. (%), and then increased for 5 wt. (%).

scholarly journals Optimization of the Curing and Post-Curing Conditions for the Manufacturing of Partially Bio-Based Epoxy Resins with Improved Toughness

Polymers ◽  
2019 ◽  
Vol 11 (8) ◽  
pp. 1354 ◽  
Author(s):  
Diego Lascano ◽  
Luis Quiles-Carrillo ◽  
Sergio Torres-Giner ◽  
Teodomiro Boronat ◽  
Nestor Montanes
Keyword(s):  
Epoxy Resin ◽  
Epoxy Resins ◽  
Polymer Network ◽  
Thermomechanical Properties ◽  
Diglycidyl Ether ◽  
Polymer Chains ◽  
Cross Linking ◽  
Reactive Diluent ◽  
Gel Time ◽  
Curing Conditions

This research deals with the influence of different curing and post-curing temperatures on the mechanical and thermomechanical properties as well as the gel time of an epoxy resin prepared by the reaction of diglycidyl ether of bisphenol A (DGEBA) with an amine hardener and a reactive diluent derived from plants at 31 wt %. The highest performance was obtained for the resins cured at moderate-to-high temperatures, that is, 80 ° C and 90 ° C , which additionally showed a significant reduction in the gel time. This effect was ascribed to the formation of a stronger polymer network by an extended cross-linking process of the polymer chains during the resin manufacturing. Furthermore, post-curing at either 125 ° C   or 150 ° C yielded thermosets with higher mechanical strength and, more interestingly, improved toughness, particularly for the samples previously cured at moderate temperatures. In particular, the partially bio-based epoxy resin cured at 80 ° C and post-cured at 150 ° C for 1 h and 30 min, respectively, showed the most balanced performance due to the formation of a more homogeneous cross-linked structure.

Evolution of Metastable Structures in Bimetallic Catalysts from Microscopy and Machine-Learning Molecular Dynamics

2020 ◽  
Author(s):  
Jin Soo Lim ◽  
Jonathan Vandermause ◽  
Matthijs A. van Spronsen ◽  
Albert Musaelian ◽  
Christopher R. O’Connor ◽  
...  
Keyword(s):  
Machine Learning ◽  
Molecular Dynamics ◽  
Large Scale ◽  
Materials Science ◽  
Complete Characterization ◽  
Layer By Layer ◽  
Surface Restructuring ◽  
Metastable Structures ◽  
Mechanistic Investigation ◽  
Underlying Mechanisms

Restructuring of interface plays a crucial role in materials science and heterogeneous catalysis. Bimetallic systems, in particular, often adopt very different composition and morphology at surfaces compared to the bulk. For the first time, we reveal a detailed atomistic picture of the long-timescale restructuring of Pd deposited on Ag, using microscopy, spectroscopy, and novel simulation methods. Encapsulation of Pd by Ag always precedes layer-by-layer dissolution of Pd, resulting in significant Ag migration out of the surface and extensive vacancy pits. These metastable structures are of vital catalytic importance, as Ag-encapsulated Pd remains much more accessible to reactants than bulk-dissolved Pd. The underlying mechanisms are uncovered by performing fast and large-scale machine-learning molecular dynamics, followed by our newly developed method for complete characterization of atomic surface restructuring events. Our approach is broadly applicable to other multimetallic systems of interest and enables the previously impractical mechanistic investigation of restructuring dynamics.

scholarly journals Toward Physicochemical and Rheological Characterization of Different Injectable Hyaluronic Acid Dermal Fillers Cross-Linked with Polyethylene Glycol Diglycidyl Ether

Polymers ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 948
Author(s):  
Nicola Zerbinati ◽  
Sabrina Sommatis ◽  
Cristina Maccario ◽  
Maria Chiara Capillo ◽  
Giulia Grimaldi ◽  
...  
Keyword(s):  
Hyaluronic Acid ◽  
Polyethylene Glycol ◽  
Biological Activities ◽  
Diglycidyl Ether ◽  
Dermal Filler ◽  
Cross Linking ◽  
Matrix Structure ◽  
Dermal Fillers ◽  
Rheological Characterization

(1) Background: Injectable hyaluronic acid (HA) dermal fillers are used to restore volume, hydration and skin tone in aesthetic medicine. HA fillers differ from each other due to their cross-linking technologies, with the aim to increase mechanical and biological activities. One of the most recent and promising cross-linkers is polyethylene glycol diglycidyl ether (PEGDE), used by the company Matex Lab S.p.A., (Brindisi, Italy) to create the HA dermal filler PEGDE family. Over the last few years, several studies have been performed to investigate the biocompatibility and biodegradability of these formulations, but little information is available regarding their matrix structure, rheological and physicochemical properties related to their cross-linking technologies, the HA content or the degree of cross-linking. (2) Methods: Seven different injectable HA hydrogels were subjected to optical microscopic examination, cohesivity evaluation and rheological characterization in order to investigate their behavior. (3) Results: The analyzed cross-linked dermal fillers showed a fibrous “spiderweb-like” matrix structure, with each medical device presenting different and peculiar rheological features. Except for HA non cross-linked hydrogel 18 mg/mL, all showed an elastic and cohesive profile. (4) Conclusions: The comparative analysis with other literature works makes a preliminary characterization of these injectable medical devices possible.

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