The curing behaviour and thermo-mechanical properties of core–shell rubber-modified epoxy nanocomposites

2018 ◽  
Vol 27 (3) ◽  
pp. 168-175
Author(s):  
Dong Quan ◽  
Alojz Ivankovic
Keyword(s):  
Mechanical Properties ◽  
Abrupt Onset ◽  
Core Shell ◽  
Curing Process ◽  
Epoxy Nanocomposites ◽  
Scanning Calorimetry ◽  
Diffusion Controlled ◽  
Reactive Groups ◽  
Higher Temperature ◽  
Physical Changes

This work investigates the effects of core–shell rubber (CSR) nanoparticles on the curing behaviour and thermo-mechanical properties of an epoxy using differential scanning calorimetry and dynamic mechanical thermal analysis approaches. Interaction between CSR nanoparticles and epoxy matrix is detected at a temperature of approximately 97°C in the curing process. This results in an increase in the glass transition temperature ( Tg) of the cured nanocomposites. Given the semi-dynamic curing schedule, the curing process of all the epoxy nanocomposites consists of an abrupt onset stage followed by a slow diffusion-controlled stage. Higher temperature is required to initiate the curing for the epoxy nanocomposites with higher loading of CSR nanoparticles. This is attributed to the physical changes caused by the addition of CSR nanoparticles, such as the increase in the viscosity and the reduction in the density of the reactive groups. The storage modulus of the epoxy decreases in the glassy region but remains constant in the rubbery region due to the incorporation of CSR nanoparticles.

scholarly journals Effect of Kenaf Alkalization Treatment on Morphological and Mechanical Properties of Epoxy/Silica/Kenaf Composite

2018 ◽  
Vol 7 (4.35) ◽  
pp. 258 ◽  
Author(s):  
Che Nor Aiza Jaafar ◽  
Muhammad Asyraf Muhammad Rizal ◽  
Ismail Zainol
Keyword(s):  
Mechanical Properties ◽  
Sodium Hydroxide ◽  
Mechanical Performance ◽  
Flexural Modulus ◽  
Charpy Impact ◽  
Charpy Impact Test ◽  
Curing Temperature ◽  
Curing Process ◽  
Scanning Calorimetry ◽  
Kenaf Fiber

The mechanical performance of silica modified epoxy at various concentration of sodium hydroxide for surface treatment of multi-axial kenaf has been analyzed. Epoxy resin with amine hardener was modified with silica powder at 20 phr and toughened by treated kenaf fiber that immerses in various concentrations of sodium hydroxide (NaOH) ranging from 0% to 9% of weight. The composite was analyzed through differential scanning calorimetry (DSC) to ensure complete curing process. The mechanical properties of the composites were analyzed through flexural test, Charpy impact test and DSC to ensure the complete curing process. DSC analysis results show epoxy sample was completely cured at above 73°C that verifies the curing temperature for preparation for the composite. Hence, 3% NaOH treated composite exhibits the best mechanical properties, with 10.6 kJ/m2 of impact strength, 54.1 MPa of flexural strength and 3.5 GPa of flexural modulus. It is due to the improvement of fiber-matrix compatibility. Analysis by SEM also revealed that a cleaner surface of kenaf fiber treated at 3% NaOH shown cleaner surface, thus, in turn, improve surface interaction between fiber and matrix of the composite. The composites produced in this work has high potential to be used in automotive and domestics appliances.

DEA and DSC study of cubic silsesquioxane epoxy resin nanocomposites

e-Polymers ◽  
2006 ◽  
Vol 6 (1) ◽  
Author(s):  
Newton Luiz Dias Filho ◽  
Hermes Adolfo de Aquino
Keyword(s):  
Mechanical Properties ◽  
Activation Energy ◽  
Fracture Toughness ◽  
Differential Scanning Calorimetry ◽  
Epoxy Resin ◽  
Loss Factor ◽  
Tensile Modulus ◽  
Dielectric Analysis ◽  
Epoxy Nanocomposites ◽  
Scanning Calorimetry

AbstractNon-isothermal dielectric analysis (DEA) and differential scanning calorimetry (DSC) techniques were used to study the epoxy nanocomposites prepared by reacting 1,3,5,7,9,11,13,15-octa[dimethylsiloxypropylglycidylether] pentaciclo [9.5.1.13,9.15,15 .17,13] octasilsesquioxane (ODPG) with methylenedianiline (MDA). Loss factor (ε”) and activation energy were calculated by DEA. The relationships between the loss factor, the activation energy, the structure of the network, and the mechanical properties were investigated. Activation energies determined by DEA and DSC, heat of polymerization, fracture toughness and tensile modulus show the same profile for mechanical properties with respect to ODPG content.

scholarly journals Curing Reaction Kinetics of the EHTPB-Based PBX Binder System and Its Mechanical Properties

Coatings ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 1266
Author(s):  
Xing Zhang ◽  
Yucun Liu ◽  
Tao Chai ◽  
Zhongliang Ma ◽  
Kanghui Jia
Keyword(s):  
Mechanical Properties ◽  
Thermal Stability ◽  
Reaction Kinetics ◽  
Testing Machine ◽  
Curing Process ◽  
Binder System ◽  
Isophorone Diisocyanate ◽  
Scanning Calorimetry ◽  
Curing Reaction ◽  
Kinetics Of

In this research, differential scanning calorimetry (DSC) was employed to compare the curing reaction kinetics of the epoxidized hydroxyl terminated polybutadiene-isophorone diisocyanate (EHTPB-IPDI) and hydroxyl terminated polybutadiene-isophorone diisocyanate (HTPB-IPDI) binder systems. Glass transition temperature (Tg) and mechanical properties of the EHTPB-IPDI and HTPB-IPDI binder systems were determined using the DSC method and a universal testing machine, respectively. For the EHTPB-IPDI binder system, the change of viscosity during the curing process in the presence of dibutyltin silicate (DBTDL) and tin 2-ethylhexanoate (TECH) catalysts was studied, and the activation energy was estimated. The results show that the activation energies (Ea) of the curing reaction of the EHTPB-IPDI and HTPB-IPDI binder systems are 53.8 and 59.1 kJ·mol−1, respectively. While their average initial curing temperatures of the two systems are 178.2 and 189.5 °C, respectively. The EHTPB-IPDI binder system exhibits a higher reactivity. Compared with the HTPB-IPDI binder system, the Tg of the EHTPB-IPDI binder system is increased by 5 °C. Its tensile strength and tear strength are increased by 12% and 17%, respectively, while its elongation at break is reduced by 10%. Epoxy groups and isocyanates react to form oxazolidinones, thereby improving the mechanical properties and thermal stability of polyurethane materials. These differences indicate that the EHTPB-IPDI binder system has better thermal stability and mechanical properties. During the EHTPB-IPDI binder system’s curing process, the DBTDL catalyst may ensure a higher viscosity growth rate, indicating a better catalytic effect, consistent with the prediction results obtained using the non-isothermal kinetic analysis method.

Design and Synthesis of Novel Hematite Core-Shell Polymeric Composites

2012 ◽  
Vol 627 ◽  
pp. 869-872
Author(s):  
Hong Wang ◽  
Xue Fei Li ◽  
Ying Wang ◽  
Jiao Ren
Keyword(s):  
Methyl Methacrylate ◽  
Chemical Interaction ◽  
Core Shell ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Emulsion Copolymerization ◽  
Design And Synthesis ◽  
Structure Morphology ◽  
Methacrylate Monomer ◽  
Higher Temperature

A novel synthetic method was developed for the preparation of core-shell composites consisting of α-Fe2O3cores with poly(styrene-co-methyl methacrylate) (P(St-co-MMA)) shells via emulsion copolymerization of styrene and methyl methacrylate monomer with surfactant of PVP. The structure, morphology and thermal properties of the composites were been characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and differential scanning calorimetry (DSC). The results confirmed that there was no chemical interaction between α-Fe2O3and copolymer, and the onset of thermal decomposition for nanocomposites shifted to a higher temperature than that for neat copolymer.

scholarly journals Bulk-Surface Modification of Nanoparticles for Developing Highly-Crosslinked Polymer Nanocomposites

Polymers ◽  
2020 ◽  
Vol 12 (8) ◽  
pp. 1820 ◽  
Author(s):  
Maryam Jouyandeh ◽  
Mohammad Reza Ganjali ◽  
Mustafa Aghazadeh ◽  
Sajjad Habibzadeh ◽  
Krzysztof Formela ◽  
...  
Keyword(s):  
Surface Modification ◽  
Polymer Nanocomposite ◽  
Isoconversional Methods ◽  
Heating Rates ◽  
Epoxy Nanocomposites ◽  
Scanning Calorimetry ◽  
Cure Reaction ◽  
Crosslinked Polymer ◽  
Diffusion Controlled ◽  
Bulk Modification

Surface modification of nanoparticles with functional molecules has become a routine method to compensate for diffusion-controlled crosslinking of thermoset polymer composites at late stages of crosslinking, while bulk modification has not carefully been discussed. In this work, a highly-crosslinked model polymer nanocomposite based on epoxy and surface-bulk functionalized magnetic nanoparticles (MNPs) was developed. MNPs were synthesized electrochemically, and then polyethylene glycol (PEG) surface-functionalized (PEG-MNPs) and PEG-functionalized cobalt-doped (Co-PEG-MNPs) particles were developed and used in nanocomposite preparation. Various analyses including field-emission scanning electron microscopy, Fourier-transform infrared spectrophotometry (FTIR), thermogravimetric analysis (TGA), X-ray diffraction (XRD) and vibrating sample magnetometry (VSM) were employed in characterization of surface and bulk of PEG-MNPs and Co-PEG-MNPs. Epoxy nanocomposites including the aforementioned MNPs were prepared and analyzed by nonisothermal differential scanning calorimetry (DSC) to study their curing potential in epoxy/amine system. Analyses based on Cure Index revealed that incorporation of 0.1 wt.% of Co-PEG-MNPs into epoxy led to Excellent cure at all heating rates, which uncovered the assistance of bulk modification of nanoparticles to the crosslinking of model epoxy nanocomposites. Isoconversional methods revealed higher activation energy for the completely crosslinked epoxy/Co-PEG-MNPs nanocomposite compared to the neat epoxy. The kinetic model based on isoconversional methods was verified by the experimental rate of cure reaction.

scholarly journals The influence of montmorillonite content on the kinetics of curing of epoxy nanocomposites

2012 ◽  
Vol 66 (6) ◽  
pp. 863-870
Author(s):  
Mirjana Jovicic ◽  
Oskar Bera ◽  
Jelena Pavlicevic ◽  
Vesna Simendic ◽  
Radmila Radicevic
Keyword(s):  
Isoconversional Methods ◽  
Curing Process ◽  
Heating Rates ◽  
Epoxy Nanocomposites ◽  
Scanning Calorimetry ◽  
Epoxy Amine ◽  
Friedman Method ◽  
Kinetics Of ◽  
Dsc Curves ◽  
Energy Activation

In this work, the attention was paid at the investigation of montmorillonite dispersion in epoxy/amine systems due to improved final properties of the nanocomposites. The influence of different montmorillonite content on the kinetics of curing of epoxy/Jeffamine D-230 systems was followed by differential scanning calorimetry (DSC). The curing of epoxy nanocomposites was performed using dynamic regime at three different heating rates: 5, 10 and 20?C/min. Three isoconversional methods were applied: two integral (Ozawa-Flynn-Wall and Kissinger-Akahira-Sunose methods) and one differential (Friedman method). The presence of montmorillonite (MMT) causes the beginning of curing at lower temperatures. The shape of the DSC curves has been changed by the addition of MMT, supporting the hypothesis of a change in the reaction mechanism. For hybrids with 3 and 5 wt.% of MMT, the E? dependence is very similar to those found for the reference system (epoxy/Jeffamine D-230) for the curing degree less than 60%. The hybrid with 10 wt.% of MMT has lower energy activation in regard to the referent system without montmorillonite. Greater differences are observed in the second part of the reaction, where it is known that the curing process is more controlled by diffusion (?>0.60). The Ea value increases at the end of the reaction (??1), which was observed for all systems, and is more pronounced in the presence of montmorillonite.

A novel process for SiGe Core-Shell JAM Transistors Fabrication and thermal annealing effect on its electrical performance

2020 ◽  
Vol 1 (2) ◽  
Author(s):  
Ashish Kumar ◽  
Wen-Hsi Lee
Keyword(s):  
Process Condition ◽  
Subthreshold Swing ◽  
Electrical Performance ◽  
Core Shell ◽  
Electrical Characteristics ◽  
Thermal Budget ◽  
New Process ◽  
Comparable Performance ◽  
Higher Temperature ◽  
Film Annealing

 In this study, we fabricate Si/SiGe core-shell Junctionless accumulation mode (JAM)FinFET devices through a rapid and novel process with four main steps, i.e. e-beam lithography definition, sputter deposition, alloy combination annealing, and chemical solution etching. The height of Si core is 30 nm and the thickness of Si/SiGe core-shell is about 2 nm. After finishing the fabrication of devices, we widely studied the electrical characteristics of poly Si/SiGe core-shell JAM FinFET transistors from a view of different Lg and Wch. A poly-Si/SiGe core -shell JAMFETs was successfully demonstrated and it also exhibits  a superior subthreshold swing of 81mV/dec and high on/off ratio > 105 when annealing for 1hr at 600°C. The thermal diffusion process condition for this study are 1hr at 600°C and 6hr at 700°C for comparison. The annealing condition at 700oC for 6 hours shows undesired electrical characteristics against the other. Results suggests that from over thermal budget causes a plenty of Ge to precipitate against to form SiGe thin film. Annealing JAMFETs at low temperature shows outstanding Subthreshold swing and better swing condition when compared to its counterpart i.e. at higher temperature. This new process can still fabricate a comparable performance to classical planar FinFET in driving current. 

850.0 and 852.0 ALUMINUM ALLOY BEARING BARS

Alloy Digest ◽  
1988 ◽  
Vol 37 (9) ◽  
Keyword(s):  
Mechanical Properties ◽  
Thermal Conductivity ◽  
Corrosion Resistance ◽  
Aluminum Alloy ◽  
Heat Treating ◽  
Light Metal ◽  
General Purpose ◽  
High Ductility ◽  
Higher Temperature ◽  
Bearing Alloy

Abstract 850.0 ALUMINUM Alloy can be considered the general purpose light metal bearing alloy. Its good thermal conductivity keeps operating temperatures low. It has high ductility. In many applications it has been found to be superior to steel backed bearings. 852.0 ALUMINUM Alloy has higher mechanical properties making it suitable for heavier load and higher temperature applications. This datasheet provides information on composition, physical properties, hardness, elasticity, tensile properties, and shear strength. It also includes information on corrosion resistance as well as heat treating and machining. Filing Code: Al-290. Producer or source: Federated Bronze Products Inc..

scholarly journals Improved Processing and Properties for Polyphenylene Oxide Modified by Diallyl Orthophthalate Prepolymer

Polymers ◽  
2019 ◽  
Vol 11 (12) ◽  
pp. 2016
Author(s):  
Honghua Wang ◽  
Qilin Mei ◽  
Yujie Ding ◽  
Zhixiong Huang ◽  
Minxian Shi
Keyword(s):  
Differential Scanning Calorimetry ◽  
Thermal Properties ◽  
Phase Separation ◽  
Dilution Effect ◽  
Gradual Decrease ◽  
Gel Point ◽  
Dynamic Mode ◽  
Curing Process ◽  
Scanning Calorimetry ◽  
Polyphenylene Oxide

Diallyl orthophthalate (DAOP) prepolymer was investigated as a reactive plasticizer to improve the processability of thermoplastics. The rheology of blends of DAOP prepolymer initiated by 2,3-dimethyl-2,3-diphenylbutane (DMDPB) and polyphenylene oxide (PPO) was monitored during the curing process, and their thermal properties and morphology in separated phases were also studied. Differential scanning calorimetry (DSC) results showed that the cure degree of the reactively plasticized DAOP prepolymer was reduced with increasing PPO due to the dilution effect. The increasing amount of the DAOP prepolymer led to a gradual decrease in the viscosity of the blends and the rheology behavior was consistent with the chemical gelation of DAOP prepolymer in blends. This indicated that the addition of the DAOP prepolymer effectively improved processability. The phase separation occurring during curing of the blend and the transition from the static to dynamic mode significantly influences the development of the morphology of the blend corresponding to limited evolution of the conversion around the gel point.

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