Fracture Toughening of Epoxy Resins by Addition of a Novel Thermoplastic PPAEs

2012 ◽  
Vol 161 ◽  
pp. 153-156 ◽  
Author(s):  
Ya Juan Xu ◽  
Si Kai Zhou ◽  
Xi Gao Jian
Keyword(s):  
Fracture Toughness ◽  
Epoxy Resins ◽  
Diglycidyl Ether ◽  
Fracture Mechanisms ◽  
Moderate Increase ◽  
Aryl Ether ◽  
Scanning Calorimetry ◽  
Fracture Toughening ◽  
The Matrix ◽  
Unmodified Epoxy

A series of blends have been prepared by adding a novel thermoplastic Poly (aryl ether) s containing phthalazinone moiety (PPAEs) in varying proportions to diglycidyl ether of bisphenol A epoxy resin (DGEBA) cured with p-diaminodiphenylsulfone (DDS). The glass transition temperature (Tg) of DGEBA /PPAEs blends were performed using differential scanning calorimetry (DSC) technique. It is proved that the addition of PPAEs resulted in enhancement of thermal properties of the blends, especially PPENK. There was moderate increase in the fracture toughness as estimated by notched impact strength. Compared to that of unmodified epoxy, the maximum toughness of the modified blends had increased 44% by addition of 15 phr PPENK. Fracture mechanisms such as plastic deformation and the ductile nature of the crack of the matrix were responsible for the increase in the fracture toughness of the blends.

The Study of Epoxy Resins Modified By PPESK

2012 ◽  
Vol 463-464 ◽  
pp. 181-184
Author(s):  
Ya Juan Xu ◽  
Qin Cun Cao ◽  
Xi Gao Jian
Keyword(s):  
Fracture Toughness ◽  
Critical Stress Intensity Factor ◽  
Diglycidyl Ether ◽  
Fracture Mechanisms ◽  
Moderate Increase ◽  
Scanning Calorimetry ◽  
Curing Reaction ◽  
Accelerated Curing ◽  
The Matrix ◽  
Kinetics Of

A series of blends have been prepared by adding a novel thermoplastic poly (phthalazinone ether sulfone ketone) (PPESK) in varying proportions to diglycidyl ether of bisphenol A epoxy resin (DGEBA) cured with p-diaminodiphenylsulfone. The kinetics of curing reaction and glass transition temperature (Tg) of PPESK/DGEBA blends were performed using differential scanning calorimetry (DSC) technique. It is proved that the addition of PPESK accelerated curing reaction and resulted in great enhancement of thermal properties of the blends. There was moderate increase in the fracture toughness as estimated by the critical stress intensity factor (KIc). Compared to that of unmodified epoxy, the maximum toughness of the modified blends had increased 32% by addition of 15 phr PPESK. Fracture mechanisms such as crack deflection and branches, ductile microcracks, ductile tearing of the thermoplastic of the matrix were responsible for the increase in the fracture toughness of the blends

scholarly journals New Biosourced Flame Retardant Agents Based on Gallic and Ellagic Acids for Epoxy Resins

Molecules ◽  
2019 ◽  
Vol 24 (23) ◽  
pp. 4305 ◽  
Author(s):  
Valeriia Karaseva ◽  
Anne Bergeret ◽  
Clément Lacoste ◽  
Hélène Fulcrand ◽  
Laurent Ferry
Keyword(s):  
Phenolic Compounds ◽  
Epoxy Resin ◽  
Epoxy Resins ◽  
Flame Retardants ◽  
Fire Behavior ◽  
Diglycidyl Ether ◽  
Scanning Calorimetry ◽  
Burning Behavior ◽  
Borate Ester ◽  
Thermal Stability Of

The aim of this work was an investigation of the ability of gallic (GA) and ellagic (EA) acids, which are phenolic compounds encountered in various plants, to act as flame retardants (FRs) for epoxy resins. In order to improve their fireproofing properties, GA and EA were treated with boric acid (to obtain gallic acid derivatives (GAD) and ellagic acid derivatives (EAD)) to introduce borate ester moieties. Thermogravimetric analysis (TGA) highlighted the good charring ability of GA and EA, which was enhanced by boration. The grafting of borate groups was also shown to increase the thermal stability of GA and EA that goes up respectively from 269 to 528 °C and from 496 to 628 °C. The phenolic-based components were then incorporated into an epoxy resin formulated from diglycidyl ether of bisphenol A (DGEBA) and isophorone diamine (IPDA) (72, 18, and 10 wt.% of DGEBA, IPDA, and GA or EA, respectively). According to differential scanning calorimetry (DSC), the glass transition temperature (Tg) of the thermosets was decreased. Its values ranged from 137 up to 108 °C after adding the phenolic-based components. A cone calorimeter was used to evaluate the burning behavior of the formulated thermosets. A significant reduction of the peak of heat release rate (pHRR) for combustion was detected. Indeed, with 10 wt.% of GA and EA, pHRR was reduced by 12 and 44%, respectively, compared to that for neat epoxy resin. GAD and EAD also induced the decrease of pHRR values by 65 and 33%, respectively. In addition, a barrier effect was observed for the resin containing GAD. These results show the important influence of the biobased phenolic compounds and their boron derivatives on the fire behavior of a partially biobased epoxy resin.

scholarly journals Comparative Study on Toughening Effect of PTS and PTK in Various Epoxy Resins

Polymers ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 518
Author(s):  
Woong Kwon ◽  
Minwoo Han ◽  
Jongwon Kim ◽  
Euigyung Jeong
Keyword(s):  
Fracture Toughness ◽  
Epoxy Resin ◽  
Tensile Properties ◽  
Epoxy Resins ◽  
Diglycidyl Ether ◽  
Low Molecular Weight ◽  
Bisphenol F ◽  
The Poor ◽  
Selection Of

This study investigated the toughening effect of in situ polytriazoleketone (PTK) and polytriazolesulfone (PTS) toughening agent when applied to various epoxy resins, such as diglycidyl ether of bisphenol A (DGEBA), diglycidyl ether of bisphenol F (DGEBF), and triglycidyl p-aminophenol (TGAP) with 3,3′-diaminodiphenylsulfone as a curing agent. The fracture toughness, tensile properties, and thermal properties of the prepared epoxy samples were evaluated and compared. When PTK was mixed with DGEBF, the fracture toughness was improved by 27% with 8.6% increased tensile strength compared to the untoughened DGEBF. When PTS was mixed with TGAP, the fracture toughness was improved by 51% without decreasing tensile properties compared to the untoughened TGAP. However, when PTK or PTS was mixed with other epoxy resins, the fracture toughness decreased or improved with decreasing tensile properties. This is attributed to the poor miscibility between the solid-state monomer of PTK (4,4′-bis(propynyloxy)benzophenone (PBP)) or PTS (4,4′-sulfonylbis(propynyloxy)benzene (SPB)) and the epoxy resin, resulting in the polymerization of low molecular weight PTK or PTS in epoxy resin. Therefore, the toughening effect of PTK or PTS can be maximized by the appropriate selection of epoxy resin based on the miscibility between PBP or SPB and the resin.

scholarly journals Evaluation of Novel Bio-Based Amino Curing Agent Systems for Epoxy Resins: Effect of Tryptophan and Guanine

Processes ◽  
2020 ◽  
Vol 9 (1) ◽  
pp. 42
Author(s):  
Stefano Merighi ◽  
Laura Mazzocchetti ◽  
Tiziana Benelli ◽  
Loris Giorgini
Keyword(s):  
Epoxy Resin ◽  
Reaction Temperature ◽  
Epoxy Resins ◽  
Diglycidyl Ether ◽  
Crosslinking Reaction ◽  
Curing Agent ◽  
Scanning Calorimetry ◽  
Agent Systems ◽  
New Class ◽  
System L

In order to obtain an environmentally friendly epoxy system, L-tryptophan and guanine were investigated as novel green curing agents for the cross-link of diglycidyl ether of Bisphenol A (DGEBA) as a generic epoxy resin model of synthetic and analogous bio-based precursors. In particular, L-tryptophan, which displays high reaction temperature with DGEBA, was used in combination with various bio-based molecules such as urea, theobromine, theophylline, and melamine in order to increase the thermal properties of the epoxy resin and to reduce the crosslinking reaction temperature. Later, in order to obtain similar properties using a single product, guanine, a totally heterocyclic molecule displaying amine functional groups, was tested as hardener for DGEBA. The thermal behavior of the precursor mixtures was evaluated by dynamic differential scanning calorimetry (DSC) leading to a preliminary screening of different hardening systems which offered a number of interesting hints in terms of bio-based compounds able to provide high Tg resins. These encouraging results pave the way for a further study of a new class of renewable, low-toxic, and sustainable curing agent systems for the production of fully bio-based epoxy resins.

scholarly journals Kinetic Analysis of the Curing of a Partially Biobased Epoxy Resin Using Dynamic Differential Scanning Calorimetry

Polymers ◽  
2019 ◽  
Vol 11 (3) ◽  
pp. 391 ◽  
Author(s):  
Diego Lascano ◽  
Luis Quiles-Carrillo ◽  
Rafael Balart ◽  
Teodomiro Boronat ◽  
Nestor Montanes
Keyword(s):  
Experimental Data ◽  
Activation Energy ◽  
Differential Scanning Calorimetry ◽  
Epoxy Resins ◽  
Curing Kinetics ◽  
Reaction Model ◽  
Diglycidyl Ether ◽  
Heating Rates ◽  
Scanning Calorimetry ◽  
Model Free

This research presents a cure kinetics study of an epoxy system consisting of a partially bio-sourced resin based on diglycidyl ether of bisphenol A (DGEBA) with amine hardener and a biobased reactive diluent from plants representing 31 wt %. The kinetic study has been carried out using differential scanning calorimetry (DSC) under non-isothermal conditions at different heating rates. Integral and derivative isoconversional methods or model free kinetics (MFK) have been applied to the experimental data in order to evaluate the apparent activation energy, Ea, followed by the application of the appropriate reaction model. The bio-sourced system showed activation energy that is independent of the extent of conversion, with Ea values between 57 and 62 kJ·mol−1, corresponding to typical activation energies of conventional epoxy resins. The reaction model was studied by comparing the calculated y(α) and z(α) functions with standard master plot curves. A two-parameter autocatalytic kinetic model of Šesták–Berggren [SB(m,n)] was assessed as the most suitable reaction model to describe the curing kinetics of the epoxy resins studied since it showed an excellent agreement with the experimental data.

Studies of vinyl ester resins and their urethanized derivatives

1993 ◽  
Vol 5 (3) ◽  
pp. 207-212 ◽  
Author(s):  
R R Pachha ◽  
J R Thakkar ◽  
R D Patel
Keyword(s):  
Vinyl Ester ◽  
Epoxy Resins ◽  
Average Molecular Weight ◽  
Diglycidyl Ether ◽  
Curing Temperature ◽  
Scanning Calorimetry ◽  
First Order ◽  
First Order Kinetics ◽  
Amino Phenol ◽  
Vinyl Ester Resins

The epoxy resins diglycidyl ether of bisphenol A and triglycidyl p-amino phenol were reacted with acrylic acid to afford the corresponding acrylated resins. These vinyl ester resins were then reacted with toluene di-isocyanate to procure their urethanized derivatives. All these resins were characterized by their viscosity, number average molecular weight and infrared spectrophotometry. Curingconditions for these resins were established by differential scanning calorimetry. The results indicated that the curing reaction follows first-order kinetics, with activation energy in the range 53-84 kJ mol-. Styrene monomer was observed to lower the curing temperature of all resin systems when incorporated prior to curing.

Fracture and R-curves in high volume fraction Al2O3/Al composites

2000 ◽  
Vol 15 (5) ◽  
pp. 1131-1144 ◽  
Author(s):  
N. Nagendra ◽  
V. Jayaram
Keyword(s):  
Fracture Toughness ◽  
Volume Fraction ◽  
Porous Alumina ◽  
Crack Tip ◽  
High Volume ◽  
Fracture Mechanisms ◽  
Constraint Factor ◽  
Ductile Phase ◽  
Crack Bridging ◽  
The Matrix

Fracture toughness and fracture mechanisms in Al2O3/Al composites are described. The unique flexibility offered by pressureless infiltration of molten Al alloys into porous alumina preforms was utilized to investigate the effect of microstructural scale and matrix properties on the fracture toughness and the shape of the crack resistance curves (R-curves). The results indicate that the observed increment in toughness is due to crack bridging by intact matrix ligaments behind the crack tip. The deformation behavior of the matrix, which is shown to be dependent on the microstructural constraints, is the key parameter that influences both the steady-state toughness and the shape of the R-curves. Previously proposed models based on crack bridging by intact ductile particles in a ceramic matrix have been modified by the inclusion of an experimentally determined plastic constraint factor (P) that determines the deformation of the ductile phase and are shown to be adequate in predicting the toughness increment in the composites. Micromechanical models to predict the crack tip profile and the bridge lengths (L) correlate well with the observed behavior and indicate that the composites can be classified as (i) short-range toughened and (ii) long-range toughened on the basis of their microstructural characteristics.

scholarly journals Efficient Improvement in Fracture Toughness of Laminated Composite by Interleaving Functionalized Nanofibers

Polymers ◽  
2021 ◽  
Vol 13 (15) ◽  
pp. 2509
Author(s):  
Seyed Mohammad Javad Razavi ◽  
Rasoul Esmaeely Neisiany ◽  
Moe Razavi ◽  
Afsaneh Fakhar ◽  
Vigneshwaran Shanmugam ◽  
...  
Keyword(s):  
Fracture Toughness ◽  
Fracture Behavior ◽  
Laminated Composite ◽  
Carbon Phase ◽  
Reinforced Composite ◽  
Reinforcing Agent ◽  
The Matrix ◽  
As Stress ◽  
Double Cantilever Beam Test ◽  
Pan Nanofiber

Functionalized polyacrylonitrile (PAN) nanofibers were used in the present investigation to enhance the fracture behavior of carbon epoxy composite in order to prevent delamination if any crack propagates in the resin rich area. The main intent of this investigation was to analyze the efficiency of PAN nanofiber as a reinforcing agent for the carbon fiber-based epoxy structural composite. The composites were fabricated with stacked unidirectional carbon fibers and the PAN powder was functionalized with glycidyl methacrylate (GMA) and then used as reinforcement. The fabricated composites’ fracture behavior was analyzed through a double cantilever beam test and the energy release rate of the composites was investigated. The neat PAN and functionalized PAN-reinforced samples had an 18% and a 50% increase in fracture energy, respectively, compared to the control composite. In addition, the samples reinforced with functionalized PAN nanofibers had 27% higher interlaminar strength compared to neat PAN-reinforced composite, implying more efficient stress transformation as well as stress distribution from the matrix phase (resin-rich area) to the reinforcement phase (carbon/phase) of the composites. The enhancement of fracture toughness provides an opportunity to alleviate the prevalent issues in laminated composites for structural operations and facilitate their adoption in industries for critical applications.

Effect of toughened polyamide-coated carbon fiber fabric on the mechanical performance and fracture toughness of CFRP

2021 ◽  
pp. 002199832199945
Author(s):  
Jong H Eun ◽  
Bo K Choi ◽  
Sun M Sung ◽  
Min S Kim ◽  
Joon S Lee
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Photoelectron Spectroscopy ◽  
Mechanical Performance ◽  
Epoxy Composites ◽  
Scanning Calorimetry ◽  
Internal Damage ◽  
Impact Tests ◽  
Flexural Tests ◽  
The Impact

In this study, carbon/epoxy composites were manufactured by coating with a polyamide at different weight percentages (5 wt.%, 10 wt.%, 15 wt.%, and 20 wt.%) to improve their impact resistance and fracture toughness. The chemical reaction between the polyamide and epoxy resin were examined by fourier transform infrared spectroscopy, differential scanning calorimetry and X-ray photoelectron spectroscopy. The mechanical properties and fracture toughness of the carbon/epoxy composites were analyzed. The mechanical properties of the carbon/epoxy composites, such as transverse flexural tests, longitudinal flexural tests, and impact tests, were investigated. After the impact tests, an ultrasonic C-scan was performed to reveal the internal damage area. The interlaminar fracture toughness of the carbon/epoxy composites was measured using a mode I test. The critical energy release rates were increased by 77% compared to the virgin carbon/epoxy composites. The surface morphology of the fractured surface was observed. The toughening mechanism of the carbon/epoxy composites was suggested based on the confirmed experimental data.

MICROSTRUCTURAL EVOLUTION OF Al-Cu-Mg-Ag ALLOY WITH TRACE Zr ADDITION DURING TWO-STEP HOMOGENIZATION

2009 ◽  
Vol 23 (06n07) ◽  
pp. 855-862 ◽  
Author(s):  
FEIYUE MA ◽  
ZHIYI LIU
Keyword(s):  
Melting Point ◽  
Grain Boundaries ◽  
Microstructural Evolution ◽  
Cast Alloy ◽  
Scanning Calorimetry ◽  
Zr Addition ◽  
Homogenization Time ◽  
The Matrix ◽  
Higher Temperature ◽  
Lower Temperature

The microstructural evolution in an Al - Cu - Mg - Ag alloy with trace Zr addition during homogenization treatment was characterized by Differential Scanning Calorimetry (DSC), Scanning Electron Microscopy (SEM) and Energy-dispersive X-ray Spectroscopy (EDS). It was shown that the low-melting-point phase segregating toward grain boundaries is Al 2 Cu , with a melting point of 523.52°C. A two-step homogenization process was employed to optimize the microstructure of the as-cast alloy, during which the alloy was first homogenized at a lower temperature, then at a higher temperature. After homogenized at 420°C for 6 h, Al 3 Zr particles were finely formed in the matrix. After that, when the alloy was homogenized at an elevated temperature for a longer time, i.e., 515°C for 24 h, most of the precipates at the grain boundaries were removed. Furthermore, the dispersive Al 3 Zr precipitates were retained, without coarsening greatly in the final homogenization step. A kinetics model is employed to predict the optimal homogenization time at a given temperature theoretically, and it confirms the result in present study, which is 420°C/6h+515°C/24h.

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