scholarly journals Optimization of Glass Transition Temperature and Pot Life of Epoxy Blends Using Response Surface Methodology (RSM)

Polymers ◽  
2021 ◽  
Vol 13 (19) ◽  
pp. 3304
Author(s):  
Ramli Junid ◽  
Januar Parlaungan Siregar ◽  
Nor Azam Endot ◽  
Jeefferie Abd Razak ◽  
Arthur N. Wilkinson
Keyword(s):  
Response Surface Methodology ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Response Surface ◽  
Diglycidyl Ether ◽  
Stoichiometric Ratio ◽  
Processing Window ◽  
Pot Life ◽  
Epoxy Blends

The aim of this work was to improve the processability of triglycidyl-p-aminophenol (TGPAP) epoxy resin. To achieve this improvement, a diluent, the diglycidyl ether of bisphenol F (DGEBF or BPF), was added to TGPAP, and the blended epoxy was then cured with 4, 4′-diaminodiphenyl sulfones (DDS). A response surface methodology (RSM) was used, with the target response being to achieve a blended resin with a high glass transition temperature (Tg) and maximum pot life (or processing window, PW). Characterization through dynamic mechanical thermal analysis (DMTA) and using a rheometer indicated that the optimum formulation was obtained at 55.6 wt.% of BPF and a stoichiometric ratio of 0.60. Both values were predicted to give Tg at 180 °C and a processing window of up to 136.1 min. The predicted values were verified, with the obtained Tg and processing window (PW) being 181.2 ± 0.8 °C and 140 min, respectively, which is close to the values predicted using the RSM.

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

Processing and characterization of titanium dioxide composites from vegetable oil resource

2011 ◽  
Vol 31 (2-3) ◽  
Author(s):  
Mohamed Aboobucker Sithique
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Flexural Modulus ◽  
Thermo Gravimetric Analysis ◽  
Percent Level ◽  
Tensile Modulus ◽  
Renewable Resource ◽  
Diglycidyl Ether ◽  
Gravimetric Analysis

Abstract TiO2 filled bio-based composites were prepared from epoxidized soy bean oil and Diglycidyl ether of bisphenol-A, in which the nano TiO2 particles were dispersed using ultra sonication method. Composites prepared with 1, 3, 5 and 7 weight percent level (wt%) of TiO2 particles were characterized for their thermal properties such as glass transition temperature and degradation stability. Thermo gravimetric analysis (TGA) showed that thermal stability of the composites increases up to 5 wt% addition of TiO2; thereafter it follows a decreasing trend, since the increased amount of nano sized particles makes it difficult for dispersion. The glass transition temperature of the composites was improved considerably. Dynamic mechanical analysis (DMA) further confirms the restricted chain mobility of the composites upon reinforcement. The significant improvements in mechanical properties such as tensile strength, tensile modulus, flexural strength, flexural modulus, and impact strength were achieved on reinforcement. The wide angle X-ray diffraction (WAXD) studies show that the nanoparticles are exfoliated in the soy based epoxy matrix system. The morphological behavior of composites studied using scanning electron microscopy (SEM) reveals the compatibility between the matrix and nanoparticles. The results showed that adding nano sized TiO2 particles can improve the properties of thermal, mechanical, compatibility and water resistance of these renewable resource based epoxy matrices suitable for engineering applications.

scholarly journals Catalytic Activity of Oxidized Carbon Waste Ashes for the Crosslinking of Epoxy Resins

Polymers ◽  
2019 ◽  
Vol 11 (6) ◽  
pp. 1011 ◽  
Author(s):  
Enrica Stasi ◽  
Antonella Giuri ◽  
Maurizio La Villetta ◽  
Domenico Cirillo ◽  
Gaetano Guerra ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Epoxy Resin ◽  
Diglycidyl Ether ◽  
Crosslinking Reaction ◽  
Scanning Calorimetry ◽  
Cure Reaction ◽  
Carbon Based

In this study, two different fillers were prepared from carbon-based ashes, produced from the wooden biomass of a pyro-gasification plant, and starting from lignocellulosic waste. The first type was obtained by dry ball-milling (DBA), while the second one was prepared by oxidation in H2O2 of the dry ball-milled ashes (oDBA). The characterization of the fillers included wide-angle x-ray diffraction (WAXD), thermogravimetric, and Fourier-transform infrared spectroscopy (FTIR) analysis. The DBA and oDBA fillers were then tested as possible catalysts for the crosslinking reaction of a diglycidyl ether of bisphenol A (DGEBA) with a diamine. The cure reaction was studied by means of rheometry and differential scanning calorimetry (DSC). The oDBA filler exhibits both a higher catalytic activity on the epoxide–amine reaction than the DBA sample and improved mechanical properties and glass transition temperature. The results obtained indicate, hence, the potential improvement brought by the addition of carbon-based waste ashes, which allow both increasing the flexural properties and the glass transition temperature of the epoxy resin and reducing the curing time, acting as a catalyst for the crosslinking reaction of the epoxy resin.

scholarly journals Model of the DGEBA-EDA Epoxy Polymer: Experiments and Simulation Using Classical Molecular Dynamics

2019 ◽  
Vol 2019 ◽  
pp. 1-9 ◽  
Author(s):  
Andreas Gavrielides ◽  
Thomas Duguet ◽  
Maëlenn Aufray ◽  
Corinne Lacaze-Dufaure
Keyword(s):  
Molecular Dynamics ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Specific Volume ◽  
Conversion Degree ◽  
Cross Linking ◽  
Stoichiometric Ratio ◽  
Covalent Bonds ◽  
Conversion Rates

Polyepoxy samples are synthesized from diglycidylether of bisphenol A (DGEBA) and ethylene diamine (EDA) monomers at a stoichiometric ratio of 2 DGEBA : 1 EDA in model conditions in order to promote a high degree of polymerization and a low density of defects and to try to approach the ideal models obtained by simulation. A slow polymerization (>24 h at ambient temperature) and a postcuring achieved in an inert atmosphere lead to a conversion degree of 92±2% and a midpoint glass transition temperature of 391±1 K. In parallel, a model is created with a multistep cross-linking procedure. In this work, all-atom molecular dynamics (MD) simulations are performed with LAMMPS and the GAFF 1.8 force field. In the initial liquid mixture of reactants (600 molecules), proper mixing is demonstrated by the calculation of the partial radial distribution functions (RDF), which show a minimum intermolecular distance of 2.8 Å and similar distributions for EDA-EDA, DGEBA-DGEBA, and DGEBA-EDA molecules in the simulation boxes. Then, in alternation with MD equilibrations, cross-linking is performed on frozen configurations by creating covalent bonds between reactive pairs within a reaction radius of 3 Å. The resulting boxes show conversion rates of 90-93% and densities close to the experimental value. Finally, a cooling ramp from 700 K to 25 K is applied in order to monitor the specific volume and the coefficient of volumetric thermal expansion (CVTE) of the polymer and to derive the glass transition temperature. Experimental thermomechanical analyses (TMA) compares well with simulations for both the specific volume and the CVTE evolutions with temperature. Whereas the uncertainty remains high with the fitting procedure used, we calculate a glass transition temperature of 390±8 K which compares very well with the experimental values (391±1 K from DSC and 380 K from TMA).

Flame–retarded epoxy resin with high glass transition temperature cured by DOPO-containing H-benzimidazole

2016 ◽  
Vol 29 (1) ◽  
pp. 94-103 ◽  
Author(s):  
Yongzhen Wang ◽  
Yanchao Yuan ◽  
Ying Zhao ◽  
Shumei Liu ◽  
Jianqing Zhao
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Epoxy Resins ◽  
Oxygen Index ◽  
Diglycidyl Ether ◽  
Testing Frequency ◽  
Flame Retarded ◽  
Halogen Free ◽  
Limited Oxygen

A halogen-free flame retardant of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide-containing H-benzimidazole (DHBI) was synthesized and subsequently used as co-curing agent of 4,4′-diamino-diphenylmethane for diglycidyl ether of bisphenol-A. The structure of DHBI was characterized by Fourier transform infrared (FTIR) spectroscopy, proton, carbon 13 and phosphorus-31 nuclear magnetic resonance, and mass spectroscopy. A series of cured epoxy resins (EPs) were prepared and their flame retardancy, thermal stability, flexibility, and dielectric properties were investigated. The resulting cured EP (EP-10) with 7.45 wt% of DHBI successfully achieved UL 94 V-0 rate with limited oxygen index of 35.6% and without dropping phenomenon. Compared with the cured pristine EP (EP-00), the glass transition temperature of EP-10 was increased by 6.9°C, accompanied with an enhancement of flexible strength by 13.1 MPa and a decrement of dielectric constant by 0.3 at the testing frequency of 1 MHz.

scholarly journals Toughening studies on an ABS/PC blend-modified epoxy resin system

1994 ◽  
Vol 6 (3) ◽  
pp. 241-248 ◽  
Author(s):  
K Natarajan ◽  
R M V G K Rao
Keyword(s):  
Fracture Toughness ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Epoxy Resin ◽  
Diglycidyl Ether ◽  
Particle Dispersion ◽  
Scanning Electron Micrographs ◽  
Epoxy Resin System ◽  
Modified Epoxy

Studies were carried out on the toughening of a bifunctional epoxy (diglycidyl ether of bisphenol-A) matrix system with an ABS/PC thermoplastic blend. The thermoplastic blend was incorporated into the epoxy matrix by particle dispersion and melt-mix methods. The unmodified and modified epoxy resin systems were cured with a stoichiometric quantity of diamino diphenyl methane (DDM). The cured castings were characterized by measurement of glass transition temperature (Tg) by DsC, evaluation of plane strain fracture toughness (Klc) by three-point bending tests and SEM analysis of non-etched and base/acid etched fracture surfaces. In genera] ABS/PC-modified (15% w/w) epoxy-resin-cured systems showed enhanced fracture toughness without lowering the glass transition temperature. The melt-mix method yielded higher fracture toughness than the particle dispersion method; this conclusion was also supported by scanning electron micrographs.

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