scholarly journals Preparation and characterization of fast-curing powder epoxy adhesive at middle temperature

2018 ◽  
Vol 5 (8) ◽  
pp. 180566 ◽  
Author(s):  
Jie Xu ◽  
Jiayao Yang ◽  
Xiaohuan Liu ◽  
Hengxu Wang ◽  
Jingjie Zhang ◽  
...  
Keyword(s):  
Activation Energy ◽  
Weight Ratio ◽  
Epoxy Adhesive ◽  
Exothermic Peak ◽  
Curing Temperature ◽  
Curing Time ◽  
Scanning Calorimetry ◽  
Cure Reaction ◽  
Exponential Factor ◽  
Blending Method

At present, the disadvantage of powder epoxy adhesive is the limited application area. In order to widen the application range of powder epoxy adhesive from heat-resistant substrates (such as metals) to heat-sensitive substrates (such as plastic products, cardboard and wood), it is necessary to decrease the curing temperature. In this article, a series of fast-curing powder epoxy adhesives were prepared by the melt blending method with bisphenol A epoxy resin (E-20), hexamethylenetetramine (HMTA) as a curing agent and 2-methylimidazole (2-MI) as an accelerant. The structure and properties of the E-20/HMTA/2-MI systems were characterized by Fourier transform infrared, thermogravimetric analysis, dynamic mechanical analyser and differential scanning calorimetry (DSC). 2-MI added into the E-20/HMTA systems can simultaneously enhance toughness, tensile strength, glass transition temperature ( T g ) and thermal stability in comparison with the E-20/HMTA systems. The best mechanical properties were obtained at 100/8/0.6 weight ratio of the E-20/HMTA/2-MI systems. DSC experiments revealed that the exothermic peak of the E-20/HMTA/2-MI system was about 55°C lower than that of the E-20/HMTA system. The activation energy of the cure reaction was determined by both Kissinger's and Ozawa's methods at any heating rates. The activation energy and pre-exponential factor were about 100.3 kJ mol −1 and 3.57 × 10 11 s −1 , respectively. According to the KAS method, the curing time of the E-20/HMTA/2-MI systems was predicted by evaluating the relationship between temperature and curing time.

A new resin with improved processability and thermal stability

2016 ◽  
Vol 29 (1) ◽  
pp. 13-25 ◽  
Author(s):  
Liping Sheng ◽  
Jingcheng Zeng ◽  
Suli Xing ◽  
Changping Yin ◽  
Jinshui Yang ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Synergistic Effect ◽  
Curing Temperature ◽  
Proton Nuclear Magnetic Resonance ◽  
Resonance Spectroscopy ◽  
Curing Time ◽  
Heating Rates ◽  
Scanning Calorimetry ◽  
Cure Reaction ◽  
Excellent Thermal Stability

To maintain outstanding thermal stability, amino- and hydroxyl-containing phthalonitrile monomers, 4-(4-aminophenoxy)-phthalonitrile (APN) and 4-(4-hydroxyphenoxy)-phthalonitrile (HPN) were selected and synthesized. Their structures were confirmed by proton nuclear magnetic resonance spectroscopy. Their curing polymers were characterized by Fourier transform infrared spectroscopy. The self-catalytic curing behaviors of the monomers were investigated by differential scanning calorimetry (DSC) at different heating rates. From the results, APN exhibits a higher curing temperature, while HPN exhibits a longer curing time. Then, mixtures of these monomers were investigated by DSC. The result shows that the 50/50 mixture exhibits different autocatalytic behaviors: the curing temperature is lower than that of APN and the curing time of the mixture is shorter than that of HPN. Furthermore, thermogravimetric analysis shows that the polymer from the mixture exhibits higher temperature of 5% weight loss ( T5%) and char yield value at 800°C than those of the polymers from each monomer. All these results indicate that the new mixture resin exhibits improved processability with excellent thermal stability, attributed to the synergistic effect between similar monomers; the synergistic effect optimizes the cure reaction kinetics and promotes cross-linking reactions, thereby producing an excellent resin; this approach is a new method for improving the processability without sacrificing thermal stability.

Non-isothermal crystallization behavior of polypropylene/zinc oxide composites

2016 ◽  
Vol 23 (5) ◽  
pp. 505-510 ◽  
Author(s):  
Jianqiang Fang ◽  
Minghua Lang ◽  
Xuchu Ye ◽  
Wei Zhang ◽  
Kongjun Zhu
Keyword(s):  
Activation Energy ◽  
Zinc Oxide ◽  
Isothermal Crystallization ◽  
Crystallization Behavior ◽  
Crystallization Kinetic ◽  
Exothermic Peak ◽  
Crystallization Time ◽  
Scanning Calorimetry ◽  
Relative Crystallinity ◽  
Oxide Composites

AbstractThe non-isothermal crystallization behavior of polypropylene (PP)/zinc oxide composites with various mass ratios was investigated by differential scanning calorimetry. The Jeziorny and Mo models were applied to calculate the non-isothermal crystallization kinetic parameters of the composites. During non-isothermal crystallization, the width of the exothermic peak increased from 7°C to 12°C with increasing cooling rate. The exothermic peak position at 10°C shifted to a lower temperature, and the half crystallization time t1/2 decreased from 2.86 min to 0.51 min. The Friedman model was used to determine the variation of activation energy at each stage of crystallization. The crystallization activation energies obtained varied significantly at each stage of crystallization. The crystallization activation energy of PP was -126.8 kJ/mol at 70% relative crystallinity but reached -232.8 kJ/mol at 10% relative crystallinity.

scholarly journals Thermal Analysis On The Kinetics Of Magnesium-Aluminum Layered Double Hydroxides In Different Heating Rates

2015 ◽  
Vol 60 (2) ◽  
pp. 1357-1359 ◽  
Author(s):  
Y. Hongbo ◽  
C. Meiling ◽  
W. Xu ◽  
G. Hong
Keyword(s):  
Activation Energy ◽  
Thermal Analysis ◽  
Layered Double Hydroxides ◽  
Heating Rates ◽  
Scanning Calorimetry ◽  
Exponential Factor ◽  
Thermal Kinetic Parameters ◽  
Double Hydroxides ◽  
Kinetics Of ◽  
Dsc Curves

Abstract The thermal decomposition of magnesium-aluminum layered double hydroxides (LDHs) was investigated by thermogravimetry analysis and differential scanning calorimetry (DSC) methods in argon environment. The influence of heating rates (including 2.5, 5, 10, 15 and 20K/min) on the thermal behavior of LDHs was revealed. By the methods of Kissinger and Flynn-Wall-Ozawa, the thermal kinetic parameters of activation energy and pre-exponential factor for the exothermic processes under non-isothermal conditions were calculated using the analysis of corresponding DSC curves.

Non-isothermal Cure Kinetics of Polybenzoxazine/Carbon Fiber Composites by Phase Change Theory

2005 ◽  
Vol 13 (6) ◽  
pp. 599-605
Author(s):  
Chunling Xin ◽  
Xiaoping Yang ◽  
Dingsheng Yu
Keyword(s):  
Carbon Fiber ◽  
Marked Change ◽  
Activation Energies ◽  
Curing Temperature ◽  
Avrami Equation ◽  
Published Data ◽  
Carbon Fiber Composites ◽  
Scanning Calorimetry ◽  
Cure Reaction ◽  
Apparent Activation Energies

The cure of benzoxazines (BA-a) and benzoxazine/carbon fiber (BA-a/CF) composites was monitored by non-isothermal differential scanning calorimetry (DSC) at various heating rates. The characteristic temperatures of BA-a and BA-a/CF were analysed. The results showed that the initial cure temperature of BA-a/CF was lower than that of BA-a at the same heating rate. Various kinetic parameters and apparent activation energies for both curing systems were obtained by using a modified version of the Avrami equation. For BA-a, the apparent activation energy was 116.8 kJ/mol, which agreed well with the published data. For BA-a/CF, the results showed that the plot of Avrami rate constant vs. 1/T was not a straight line for the whole curing temperature range, but it displayed a marked change in slope at around 220 oC. The apparent activation energies at primary and second section were 105.6 kJ/mol and 224.8 kJ/mol respectively. The cure reaction of benzoxazines was not only catalysed by carbon fiber, but also was retarded by it.

scholarly journals In-Out Surface Modification of Halloysite Nanotubes (HNTs) for Excellent Cure of Epoxy: Chemistry and Kinetics Modeling

Nanomaterials ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 3078
Author(s):  
Shahab Moghari ◽  
Seyed Hassan Jafari ◽  
Mohsen Khodadadi Yazdi ◽  
Maryam Jouyandeh ◽  
Aleksander Hejna ◽  
...  
Keyword(s):  
Surface Modification ◽  
Surface Engineering ◽  
Reaction Order ◽  
Halloysite Nanotubes ◽  
Significant Rise ◽  
Autocatalytic Reaction ◽  
Scanning Calorimetry ◽  
Cure Reaction ◽  
Exponential Factor ◽  
Dsc Measurements

In-out surface modification of halloysite nanotubes (HNTs) has been successfully performed by taking advantage of 8-hydroxyquinolines in the lumen of HNTs and precisely synthesized aniline oligomers (AO) of different lengths (tri- and pentamer) anchored on the external surface of the HNTs. Several analyses, including FTIR, H-NMR, TGA, UV-visible spectroscopy, and SEM, were used to establish the nature of the HNTs’ surface engineering. Nanoparticles were incorporated into epoxy resin at 0.1 wt.% loading for investigation of the contribution of surface chemistry to epoxy cure behavior and kinetics. Nonisothermal differential scanning calorimetry (DSC) data were fed into home-written MATLAB codes, and isoconversional approaches were used to determine the apparent activation energy (Eα) as a function of the extent of cure reaction (α). Compared to pristine HNTs, AO-HNTs facilitated the densification of an epoxy network. Pentamer AO-HNTs with longer arms promoted an Excellent cure; with an Eα value that was 14% lower in the presence of this additive than for neat epoxy, demonstrating an enhanced cross-linking. The model also predicted a triplet of cure (m, n, and ln A) for autocatalytic reaction order, non-catalytic reaction order, and pre-exponential factor, respectively, by the Arrhenius equation. The enhanced autocatalytic reaction in AO-HNTs/epoxy was reflected in a significant rise in the value of m, from 0.11 to 0.28. Kinetic models reliably predict the cure footprint suggested by DSC measurements.

Curing Kinetics of Octaepoxysilsesquioxane/DDS System

2011 ◽  
Vol 233-235 ◽  
pp. 1834-1837
Author(s):  
Zeng Ping Zhang ◽  
Jian Zhong Pei ◽  
Shuan Fa Chen ◽  
Hong Zhao Du ◽  
Yong Wen
Keyword(s):  
Activation Energy ◽  
Differential Scanning Calorimetry ◽  
Curing Kinetics ◽  
Scanning Calorimetry ◽  
Exponential Factor ◽  
Inorganic Hybrid ◽  
Oligomeric Silsesquioxane ◽  
Kinetics Of ◽  
Epoxy Groups ◽  
Important Kind

Polyhedral oligomeric silsesquioxane (POSS) can be incorporated into polymers to obtain organic/inorganic hybrid materials. Octaepoxysilsesquioxane (E-POSS) with eight reactive epoxy groups per molecule is an important kind of POSS. E-POSS was cured with 4,4'-diaminodiphenylsulfone diamine (DDS) in this study. The curing kinetics of the E-POSS/DDS system was studied by using differential scanning calorimetry (DSC). Kinssinger and Flynn-Wall-Ozawa methods were used to obtain the activation energy and pre-exponential factor of the curing reaction.

Curing Kinetics of Phenol Formaldehyde Resin Modified with Sodium Silicate

2012 ◽  
Vol 184-185 ◽  
pp. 1471-1479
Author(s):  
Jin Sun ◽  
Xiao Feng Zhu ◽  
Xiao Bo Wang ◽  
Rui Hang Lin ◽  
Zhen Zhong Gao
Keyword(s):  
Activation Energy ◽  
Sodium Silicate ◽  
Reaction Order ◽  
Phenol Formaldehyde ◽  
Curing Kinetics ◽  
Curing Temperature ◽  
Formaldehyde Resin ◽  
Exponential Factor ◽  
Curing Reaction ◽  
Kinetics Of

The curing kinetics of PF resin modified with sodium silicate had been investigated by differential scanning calorimetry (DSC). The kinetic analysis was performed at heating rates of 5, 10, 15, and 20°C/min，respectively. The kinetic parameters such as reaction order and activation energy were solved by Kissinger and Crane equation. The relationship between curing temperature and heating rate was also investigated. The activation energy and the curing reaction order，which were obtained by kinetic calculation, are 83.00kJ/mol and 0.917, respectively. The curing reaction kinetics equations were built by the obtained best curing temperature, reaction order, pre-exponential factor and reaction rate constant.

scholarly journals The effects of alkyd/melamine resin ratio and curing temperature on the properties of the coatings

2005 ◽  
Vol 70 (4) ◽  
pp. 593-599 ◽  
Author(s):  
Radmila Radicevic ◽  
Jaroslava Budinski-Simendic
Keyword(s):  
Protective Coatings ◽  
Impact Resistance ◽  
Curing Temperature ◽  
Curing Time ◽  
Melamine Resin ◽  
Coating Properties ◽  
Scanning Calorimetry ◽  
Synthetic Resins ◽  
Degree Of Curing ◽  
Resin Mixture

Abstract: Synthetic resins are used as binders in protective coatings. An alkyd/melamine resin mixture is the usual composition for the preparation of a coating called "baking enamel" cured through functional groups of resins. The effects of the alkyd/butylated melamine resin ratio (from 85/15 to 70/30) and curing temperature (from 100 ?C to 160 ?C) on the crosslinking and properties of the coating are presented in this paper. The degree of curing was determined by differential scanning calorimetry. These data were used for the estimation of the degree of crosslinking. The hardness, elasticity impact resistance, degree of adherence and gloss were also determined. Optimal coating properties could be achieved with an alkyd/melamine resin ratio of 75/25, a curing temperature of 130 ?C and a curing time of 30 min.

Preparation and Performance Testing of Flexible PDLC Films

2014 ◽  
Vol 1015 ◽  
pp. 89-92 ◽  
Author(s):  
Ya Jing An ◽  
Xin Liang Guo ◽  
Sheng Han Zhang ◽  
Zong Qiang Du
Keyword(s):  
Optical Properties ◽  
Liquid Crystal ◽  
Film Thickness ◽  
Threshold Voltage ◽  
Contrast Ratio ◽  
Weight Ratio ◽  
Performance Testing ◽  
Preparation Condition ◽  
Curing Temperature ◽  
Curing Time

A new kind of polymer dispersed liquid crystal (PDLC) films based on nematic liquid crystal E7 and pre-polymeric composition epoxy resin E51 were prepared by polymerization induced phase separation via heating curing in this paper. The electro-optical properties of PDLC films were affected by many processing factors, for example, the weight ratio of the pre-polymer and liquid crystal, the curing temperature, curing time and film thickness. The electro-optical properties of PDLCs fabricated under different conditions were tested. The performance parameters such as contrast ratio, threshold voltage and the saturation voltage were calculated. In our case, the optimal preparation condition was 65% liquid crystal content with a curing time of 6 hours at 65oC. The PDLC film prepared in this paper showed a threshold voltage of 14.11V and a saturation voltage of 49.47V. The effect of film thickness on the electro-optical properties of PDLCs had been analyzed as well. The threshold voltage and saturation voltage of PDLC increase as the film thickness increases as so as the contrast ratio.

Study on the Curing Characteristics of MUF Co-Polymerization Resin

2011 ◽  
Vol 183-185 ◽  
pp. 2124-2128
Author(s):  
Yun Wu Zheng ◽  
Li Bin Zhu ◽  
Ji You Gu ◽  
Zhi Feng Zheng ◽  
Yuan Bo Huang
Keyword(s):  
Activation Energy ◽  
Reaction Rate ◽  
Reaction Order ◽  
Curing Temperature ◽  
Curing Agent ◽  
Curing Time ◽  
Curing Reaction ◽  
Curing Characteristics ◽  
Production Practice ◽  
Run Up

Curing is the key to the bonding, this paper considered the production practice, studied the curing properties of different MUF resin under the different curing agent with DSC. The experimental results show that: The characteristics temperature of curing reaction is closely related to the β. With the increase of β, the initial and peak temperature is moving to the high-temperature, the curing time became shorter; the range of curing temperature became much wider. At the same time, the curing peaking temperature was decreased and the Enthalpy integral of curing reaction was reduced first then increased with the increased of the amount of curing agent. When the amount of curing agent occupied 4.0%-6.0% of the MUF resin, the pH was decreased mostly, and the curing reaction rate run up quickly Along with the increasing of n (F): n (U1), the To, Tp and Ti are going ahead distinctly after hardening. At the same time, both activation energy and reaction order are all decreased, absorbed heat is dropping too. So, curing technics became easily.

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