scholarly journals Electrical Resistance Sensing of Epoxy Curing Using an Embedded Carbon Nanotube Yarn

Sensors ◽  
2020 ◽  
Vol 20 (11) ◽  
pp. 3230 ◽  
Author(s):  
Omar Rodríguez-Uicab ◽  
Jandro L. Abot ◽  
Francis Avilés
Keyword(s):  
Carbon Nanotube ◽  
Epoxy Resin ◽  
Electrical Resistance ◽  
Electrical Response ◽  
Curing Kinetics ◽  
Curing Temperature ◽  
Polymerization Process ◽  
Curing Agent ◽  
Resin Curing ◽  
Over Time

Curing effects were investigated by using the electrical response of a single carbon nanotube yarn (CNTY) embedded in an epoxy resin during the polymerization process. Two epoxy resins of different viscosities and curing temperatures were investigated, varying also the concentration of the curing agent. It is shown that the kinetics of resin curing can be followed by using the electrical response of an individual CNTY embedded in the resin. The electrical resistance of an embedded CNTY increased (~9%) after resin curing for an epoxy resin cured at 130 °C with viscosity of ~59 cP at the pouring/curing temperature (“Epon 862”), while it decreased (~ −9%) for a different epoxy cured at 60 °C, whose viscosity is about double at the corresponding curing temperature. Lowering the curing temperature from 60 °C to room temperature caused slower and smoother changes of electrical resistance over time and smaller (positive) residual resistance. Increasing the concentration of the curing agent caused a faster curing kinetics and, consequently, more abrupt changes of electrical resistance over time, with negative residual electrical resistance. Therefore, the resin viscosity and curing kinetics play a paramount role in the CNTY wicking, wetting and resin infiltration processes, which ultimately govern the electrical response of the CNTY immersed into epoxy.

Study on the Preparation of 2-Phenyl Imidazole Microcapsule and its Effect on Curing Epoxy Resin

2013 ◽  
Vol 690-693 ◽  
pp. 1649-1652
Author(s):  
Ai Jie Ma ◽  
Qiu Yu Zhang ◽  
You Qiang Shi
Keyword(s):  
Epoxy Resin ◽  
Raw Materials ◽  
Curing Kinetics ◽  
Curing Temperature ◽  
Curing Agent ◽  
Thermal Analyzer ◽  
Epoxy Resin System ◽  
Curing Kinetic ◽  
Resin Curing ◽  
Micro Morphology

In this paper, 2-phenyl imidazole (2-PZ) microcapsule-type curing agent of epoxy resin were prepared through solvent volatilization with 2-PZ and polymethyl acrylic glycidyl ester (PGMA) as the raw materials. The micro-morphology, shape and structure of the microcapsules were studied by scanning electronic microscope (SEM) and fourier transform infrared spectrum (FT-IR). The curing kinetics of microcapsule curing agent/epoxy resin E-44 curing system were studied using TGA/DSC simultaneous thermal analyzer. Results showed that the preparation method is simple and effective and the prepared 2-PZ microcapsules have smooth surfaces and monodisperse size. And the curing kinetic study of epoxy resin system suggested epoxy resin curing temperature was rising with the increase of heating rate.

EFFECT OF CURING TEMPERATURE OF EPOXY RESIN ON THE ELECTRICAL RESPONSE OF CARBON NANOTUBE YARN MONOFILAMENT COMPOSITES

2021 ◽  
Author(s):  
OMAR RODRIGUEZ-UICAB ◽  
JANDRO L. ABOT ◽  
FRANCIS AVILÉS
Keyword(s):  
Carbon Nanotube ◽  
Epoxy Resin ◽  
Electrical Resistance ◽  
Epoxy Resins ◽  
Room Temperature ◽  
Negative Temperature Coefficient ◽  
Electrical Response ◽  
Negative Temperature ◽  
Curing Temperature ◽  
Temperature Coefficient Of Resistance

The cyclic thermoresistive response of individual carbon nanotube yarns (CNTYs) embedded into epoxy resins is investigated. The influence of the temperature at which the epoxy resin cures on the thermoresistive response is investigated by using two epoxy resins, one that cures at room temperature and the other one that cures at 130 °C. Heating-cooling cycles ranging from room temperature (RT, 25 °C) to 80 °C, incremental cycles (RT to 40 °C, RT to 60 °C and RT to 80 °C) and incremental heating-dwell cycles are applied to monofilament composites, while their electrical resistance is simultaneously recorded. The monofilament composites showed a negative temperature coefficient of resistance during the heating-cooling cycles of -7.07x10-4 °C-1 for specimens cured at high temperature, and -5.93x10-4 °C-1 for specimens cured at room temperature. The hysteresis after the different heating-cooling cycles was slightly smaller for specimens cured at 130 °C, in comparison to specimens cured at room temperature. Several factors including the intrinsic thermoresistivity of CNTY, level of infiltration and the effect of curing temperature may explain the thermoresistive sensitivity of the monofilament composites.

CYCLIC THERMORESISTIVITY OF CARBON NANOTUBE YARN/SILICONE RUBBER MATRIX MONOFILAMENT COMPOSITES

2021 ◽  
Author(s):  
TANNAZ TAYYARIAN ◽  
OMAR RODRIGUEZ-UICAB ◽  
TANJEE AFREEN ◽  
JANDRO L. ABOT
Keyword(s):  
Carbon Nanotube ◽  
Electrical Resistance ◽  
Room Temperature ◽  
Electrical Response ◽  
Negative Temperature ◽  
Curing Kinetics ◽  
Rubber Matrix ◽  
Continuous Heating ◽  
Average Value ◽  
Heating And Cooling

Thermoresistive characterization of CNTY monofilament composites was investigated by using the electrical response of a single carbon nanotube yarn (CNTY) embedded in a silicone polymer forming monofilament composites. Two room temperature vulcanizing (RTV) silicone rubbers with different polymerization mechanisms (OOMOO and Ecoflex) were used as the polymeric matrices. Continuous heating-cooling thermal cycling ranging from room temperature (RT~25 °C) to 80 °C was performed in order to determine the thermoresistive sensitivity, hysteresis and residual fractional change in electrical resistance after each cycle. The thermoresistive response was nearly linear, with negative temperature coefficient of resistance at the heating and cooling zones for CNTY/ OOMOO and CNTY/Ecoflex specimens. The average value of this coefficient at the heating and cooling sections was - 6.65×10-4 °C-1 for CNTY/OOMOO and -7.35×10-4 °C-1 for CNTY/Ecoflex. Both monofilament composites showed a negligible negative residual electrical resistance with an average value of ~ -0.08% for CNTY/OOMOO and ~ -0.20% for CNTY/Ecoflex after each cycle. The hysteresis yielded ~19.3% for CNTY/OOMOO and ~29.2% in CNTY/Ecoflex after each cycle. Therefore, the curing kinetics and viscosity play a paramount role in the electrical response of the CNTY immersed into these rubbery matrices.

scholarly journals Monitoring of Curing and Cyclic Thermoresistive Response Using Monofilament Carbon Nanotube Yarn Silicone Composites

2021 ◽  
Vol 7 (3) ◽  
pp. 60
Author(s):  
Tannaz Tayyarian ◽  
Omar Rodríguez-Uicab ◽  
Jandro L. Abot
Keyword(s):  
Carbon Nanotube ◽  
Heating Rate ◽  
Electrical Resistance ◽  
Room Temperature ◽  
Electrical Response ◽  
Negative Temperature ◽  
Curing Kinetics ◽  
Curing Process ◽  
Resistance Change ◽  
Electrical Resistance Change

The curing process and thermoresistive response of a single carbon nanotube yarn (CNTY) embedded in a room temperature vulcanizing (RTV) silicone forming a CNTY monofilament composite were investigated toward potential applications in integrated curing monitoring and temperature sensing. Two RTV silicones of different crosslinking mechanisms, SR1 and SR2 (tin- and platinum-cured, respectively), were used to investigate their curing kinetics using the electrical response of the CNTY. It is shown that the relative electrical resistance change of CNTY/SR1 and CNTY/SR2 monofilament composites increased by 3.8% and 3.3%, respectively, after completion of the curing process. The thermoresistive characterization of the CNTY monofilament composites was conducted during heating–cooling ramps ranging from room temperature (RT~25 °C) to 100 °C. The thermoresistive response was nearly linear with a negative temperature coefficient of resistance (TCR) at heating and cooling sections for both CNTY/SR1 and CNTY/SR2 monofilament composites. The average TCR value was −8.36 × 10−4 °C−1 for CNTY/SR1 and −7.26 × 10−4 °C−1 for CNTY/SR2. Both monofilament composites showed a negligible negative residual relative electrical resistance change with average values of ~−0.11% for CNTY/SR1 and ~−0.16% for CNTY/SR2 after each cycle. The hysteresis amounted to ~21.85% in CNTY/SR1 and ~29.80% in CNTY/SR2 after each cycle. In addition, the effect of heating rate on the thermoresistive sensitivity of CNTY monofilament composites was investigated and it was shown that it reduces as the heating rate increases.

HIGH TECHNIQUE FOR T-PEEL STRENGTH ENHANCEMENT OF Al/AFRP HYBRID COMPOSITE

2006 ◽  
Vol 20 (25n27) ◽  
pp. 4273-4278
Author(s):  
CHEOL-WOONG KIM ◽  
DONG-JOON OH
Keyword(s):  
Tensile Strength ◽  
Epoxy Resin ◽  
Hybrid Composite ◽  
Equivalence Ratio ◽  
Peel Strength ◽  
Aramid Fiber ◽  
Curing Agent ◽  
Mixture Ratio ◽  
Resin Mixture ◽  
Resin Curing

The interlaminar peel strength of Al / AFRP (Aluminum alloy/Aramid Fiber Reinforced Plastic) hybrid composite is affected by the adhesive strength between the Al alloy layer and the aramid fiber layer. The study of the tensile strength and the T-peel strength of the Al / AFRP should be accomplished first. Therefore, this study focused on the effect of the resin mixture ratio as the Al / AFRP on the tensile strength and T-peel strength. In conclusions, the resin mixture ratio by equivalence ratio of 〈epoxy resin : curing agent〉 equal to 〈1:1〉 of Al / AFRP -I and the resin mixture ratio by equivalence ratio of 〈epoxy resin : curing agent : accelerator〉 equal to 〈1:1:0.2〉 of Al / AFRP -II showed the highest ultimate tensile strength. After the T-peel test, it is found that the T-peel strength of Al / AFRP -II is approximately 1.5 times higher than that of Al / AFRP -I. Reviewing the characteristics of the tensile and T-peel strengths, the resin mixture ratio 〈1:1:0.2〉 of Al / AFRP -II showed the highest tensile strength and T-peel strength.

Studies on Mechanical and Thermal Properties of Epoxy Resin Modified by Fluorine-Containing Silicone

2013 ◽  
Vol 401-403 ◽  
pp. 713-716
Author(s):  
Cheng Fang ◽  
Dong Bo Guan ◽  
Wei Guo Yao ◽  
Shou Jun Wang ◽  
Hui An
Keyword(s):  
Glass Transition ◽  
Thermal Properties ◽  
Epoxy Resin ◽  
Bending Strength ◽  
Mechanical And Thermal Properties ◽  
Curing Agent ◽  
Epoxy System ◽  
Resin Curing ◽  
The Impact ◽  
Modified Epoxy

The epoxy resin was modified with the mixture of α,ω-dihydroxy poly-(3,3,3-trifluoropropyl) siloxane (PTFPMS), KH560 and stannous octoate. KH560 can react with PTFPMS and also epoxy resin curing agent. The two reactions were characterized by FI-IR. The modified epoxy resin was characterized by FI-IR. The result showed that fluorine-containing silicone had been successfully introduced into the epoxy system. The mechanical and thermal properties of the modified epoxy resin were analyzed. The results showed that with the increase of PTFPMS the impact strength of epoxy resin increased, hardness and bending strength correspondingly reduced, slight decrease in the glass transition temperature.

The Study on Curing Kinetics of Lignin Based Epoxy Resin System Using Non-Isothermal DSC Method

2013 ◽  
Vol 788 ◽  
pp. 223-227 ◽  
Author(s):  
Ming Qiang Chen ◽  
Shao Min Liu ◽  
Feng Li ◽  
Zhong Lian Yang ◽  
Ye Zhang
Keyword(s):  
Epoxy Resin ◽  
Kinetic Parameters ◽  
Raw Materials ◽  
Curing Kinetics ◽  
Reaction Model ◽  
Curing Temperature ◽  
Resin System ◽  
Curing Reaction ◽  
Epoxy Resin System ◽  
Dsc Method

The synthesis of Lignin Base Epoxy Resin was based on industrial alkali lignin, and lignin-based epoxy resin curing characteristics were analyzed using the thermal weight loss technology under the oxygen atmosphere conditions. In light of the infra-red analysis of raw materials, the curing reaction kinetic parameters of lignin-based epoxy resin system were calculated using the Kissinger-Crane and Flynn-Wall-Ozawa method, and the curing reaction kinetics model of lignin-based epoxy resin system was established. The results showed that the kinetic parameters obtained using two methods were approximate, which validated that the curing reaction was consistent with the principle of the first-order reaction model. Initial curing temperature Ti0=454.88 K, curing temperature Tp0=507.55 K, and terminal temperature Tf0=598.77 K of lignin-based epoxy resin system were obtained when the extrapolation method was applied.

Preparation of waterborne P-N containing epoxy resin curing and its performances

2016 ◽  
Vol 45 (5) ◽  
pp. 308-312 ◽  
Author(s):  
Wei Li ◽  
Guilong Xu ◽  
Buqin Xu ◽  
Yi Wang ◽  
Jin Yang ◽  
...  
Keyword(s):  
Flame Retardant ◽  
Epoxy Resin ◽  
Flame Retardancy ◽  
Curing Agent ◽  
Flame Resistance ◽  
Pencil Hardness ◽  
Content Type ◽  
Coating Industry ◽  
Epoxy Curing ◽  
Resin Curing

Purpose The flammability of epoxy resin is a major disadvantage in applications that require flame resistance. Epoxy monomers and hardeners containing flame-retardant elements are molecularly incorporated in the resin network are expected to exhibit better flame resistance than those borne on an additive approach. In recent years, because of health and environmental regulation, the use of waterborne coatings has received many attentions. However, waterborne epoxy resin curing agent with excellent flame retardancy has been seldom reported. The paper aims to study the preparation of waterborne P-N-containing epoxy resin curing agent and its performances (P-N – phosphorous and nitrogen). Design/methodology/approach Waterborne P-N-containing epoxy curing agent was prepared in this study using reactive flame retardant 10-(2,5-dihydroxyphenyl)-9,10-dihydro-9-xa-10-phosphaphenanthrene-10-oxide, liquid epoxy resin, triethylenetetramine and butyl glycidyl ether at the mole ratio of 1.0:2.0:2.0:2.0. Findings The results show that the epoxy thermoset from the prepared P-N-containing curing agent presents good flame retardancy and can pass the V-1 rating, and the cured epoxy thermoset film presents excellent performances such as water resistance, adhesion, impact resistance and pencil hardness. This study provides useful suggestions for the application of the water-borne flame retardancy epoxy resins in coating industry. Research limitations/implications Each step of products during the preparation of waterborne P-N-containing epoxy curing agent cannot be accurately tested. Originality/value This method for synthesis of waterborne P-N-containing epoxy curing agent is novel and could be used for various applications in epoxy coating industry.

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