Study on the Cure Kinetic Behavior of Thermosetting Polyurethane Solids and Foams: Effect of Temperature, Density, and Carbon Nanofiber

2010 ◽  
Vol 133 (1) ◽  
Author(s):  
Mrinal C. Saha ◽  
Bipul Barua ◽  
Sriram Mohan
Keyword(s):  
Reaction Rate ◽  
Carbon Nanofiber ◽  
Polymerization Reaction ◽  
Shear Mode ◽  
Kinetic Behavior ◽  
Cure Reaction ◽  
Cure Behavior ◽  
Pu Foam ◽  
Cure Kinetic ◽  
Reaction Orders

Cure kinetic behavior was studied for both thermosetting polyurethane (PU) solids and foams. The effects of cure temperature, foam density, and carbon nanofiber (CNF) contents were examined. Cure studies were performed experimentally by measuring the evolution of complex shear modulus as a function of time using an advanced polymer analyzer operating in dynamic shear mode. Isothermal cure behavior of PU solid and foams was investigated at four different temperatures, namely, 25°C, 45°C, 60°C, and 80°C and at three different amounts of CNF, namely, 0.01%, 0.05%, and 0.1% by weight. The cure data were analyzed by using an autocatalytic cure kinetic model. The cure behavior of both solid and foam was found to be temperature dependent. Addition of CNF was also found to affect the cure behavior of the PU foam. It was observed that the PU foam with 0.1% CNF shows the highest polymerization reaction compared with the neat foam. It was also observed that the reaction rate constants follow an Arrhenius dependence on temperature, whereas the reaction orders remain fairly constant. A simple predictive model using the reaction orders indicated that the maximum cure reaction rate was occurred at 37.5% conversion.

Cure Kinetic Behavior of 191# Unsaturated Polyester Resin Used in Advanced Composites

2006 ◽  
Vol 326-328 ◽  
pp. 1271-1274 ◽  
Author(s):  
Mei Yang ◽  
Shi Lin Yan ◽  
Mei Liu
Keyword(s):  
Polyester Resin ◽  
Unsaturated Polyester ◽  
Cure Kinetics ◽  
Unsaturated Polyester Resin ◽  
Kinetic Properties ◽  
Heating Rates ◽  
Cure Reaction ◽  
Exponential Factor ◽  
Maximum Reaction Rate ◽  
Cure Kinetic

The cure kinetic properties of 191# resin was studied by means of the differential scanning calorimeter (DSC) data. Dynamic DSC scanning at four different heating rates (5, 10, 15 and 20/min) are employed to investigate the cure kinetics. DSC curves show that there are two exothermal peaks. Kissinger’s method is applied to processing the data. The activation energy E and pre-exponential factor A were gained by linear regress and the cure kinetics model was developed. Based on T − β method, the temperatures of cure reaction beginning, maximum reaction rate and reaction ending were obtained. These will help to process designing of unsaturated polyester resin used in advanced composite materials.

Mechanical Properties of Electrospun Carbon Nano Fiber (ECNF)/Epoxy Nanocomposites

2007 ◽  
Author(s):  
Darunee Aussawasathien ◽  
Erol Sancaktar
Keyword(s):  
Mechanical Properties ◽  
Aspect Ratio ◽  
Epoxy Resin ◽  
Carbon Nanofiber ◽  
Mechanical Analysis ◽  
Short Fiber ◽  
Neat Epoxy ◽  
Epoxy Nanocomposites ◽  
Cure Reaction ◽  
Fiber Aspect Ratio

Electrospun polyacrylonitrile (PAN) fiber precursor based Carbon Nanofiber (CNF) mats were produced and impregnated with epoxy resin. The mechanical properties of as-prepared nanofibers in the mat and short fiber filled epoxy nanocomposite forms were determined to demonstrate the effect of fiber aspect ratio and interconnecting network on those properties. Our experimental results reveal that epoxy nanocomposites containing Electrospun Carbon Nano Fibers (ECNF) with high fiber aspect ratio and high interconnecting network in the non-woven mat form yield better mechanical properties than those filled with short ECNFs. The ECNF mat in epoxy nanocomposites provides better homogeneity, more interlocking network, and easier preparation than short ECNFs. Mechanical properties of ECNF mat-epoxy nanocomposites, which we obtained using tensile and flexural tests, such as stiffness and modulus increased, while toughness and flexural strength decreased, compared to the neat epoxy resin. Dynamic Mechanical Analysis (DMA) results showed, higher modulus for ECNF mat-epoxy nanocomposites, compared to those for neat epoxy resin and short ECNF-epoxy nanocomposites. The epoxy nanocomposites had high modulus, even though the glass transition temperature, Tg values dropped at some extents of ECNF mat contents when compared with the neat epoxy resin. The cure reaction was retarded since the amount of epoxy and hardener decreased at high ECNF contents together with the hindering effect of the ECNF mat to the diffusion of epoxy resin and curing agent, leading to low crosslinking efficiency.

scholarly journals Dynamic Cure Kinetics and Physical-Mechanical Properties of PEG/Nanosilica/Epoxy Composites

2020 ◽  
Vol 2020 ◽  
pp. 1-10 ◽  
Author(s):  
Haleh Nowruzi Varzeghani ◽  
Iraj Amiri Amraei ◽  
Seyed Rasoul Mousavi
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Cure Kinetics ◽  
Diglycidyl Ether ◽  
Solid Particles ◽  
Scanning Calorimetry ◽  
Cure Reaction ◽  
Cure Kinetic ◽  
Cure Temperature ◽  
Kinetics Of

This study investigated the effect of polyethylene glycol (PEG) and nanosilica (NS) on the physical-mechanical properties and cure kinetics of diglycidyl ether of bisphenol-A-based epoxy (DGEBA-based EP) resin. For this purpose, tensile and viscometry tests, dynamic mechanical thermal analysis (DMTA), and differential scanning calorimetry (DSC) were carried out under dynamic conditions. The results showed that adding NS and PEG enhances the maximum cure temperature as well as the heat of cure reaction (ΔH) in EP-NS, while it decreases in EP-PEG and EP-PEG-NS. The cure kinetic parameters of EP-PEG-NS were calculated by Kissinger, Ozawa, and KSA methods and compared with each other. The Ea calculated from the Kissinger method (96.82 kJ/mol) was found to be lower than that of the Ozawa method (98.69 kJ/mol). Also, according to the KAS method, the apparent Ea was approximately constant within the 10-90% conversion range. Tensile strength and modulus increased by adding NS, while tensile strength diminished slightly by adding PEG to EP-NS. The glass transition temperature (Tg) was calculated using DMTA which was increased and decreased by the addition of NS and PEG, respectively. The results of the viscometry test showed that the viscosity increased with the presence of both PEG and NS and it prevented the deposition of solid particles.

Study of an A+2B--->C Reaction-Diffusion System with Initially Separated Components

1994 ◽  
Vol 366 ◽  
Author(s):  
Andrew Yen ◽  
Raoul Kopelman
Keyword(s):  
Reaction Front ◽  
Reaction Rate ◽  
Reaction Diffusion ◽  
Biological Processes ◽  
Local Production ◽  
Kinetic Behavior ◽  
Acetate Trihydrate ◽  
Physical Chemical ◽  
Global Reaction ◽  
Front Dynamics

ABSTRACTThe presence of a reaction front is a characteristic feature of a variety of physical, chemical and biological processes. A chemical reaction exhibits a front (spatially localized region where concentration of product is non zero), provided the diffusing reactants are separated in space. We study the reaction front dynamics of a termolecular A+2B--->C reaction with initially separated components in a capillary. The reaction tetra+2Ni2+--->1:2 complex is used, where ‘tetra’ is disodium ethyl bis(5-tetrazolylazo) acetate trihydrate. We measure and compare with theory the dynamic quantities that characterize the kinetic behavior of the system: the global reaction rate R(t), the location of the reaction center xf(t), the front's width w(t), and the local production rate R(xf,t). The non-classical nature of this dynamical system is confirmed.

scholarly journals Effect of Micellar Aggregate on the Kinetics and Mechanism of the Reaction between Ethylene Glycol and Periodate

2014 ◽  
Vol 2014 ◽  
pp. 1-3
Author(s):  
Olaseni Segun Esan
Keyword(s):  
Ethylene Glycol ◽  
Cetyltrimethylammonium Bromide ◽  
Reaction Rate ◽  
The Other ◽  
Bulk Solution ◽  
Kinetic Behavior ◽  
Pseudophase Model ◽  
Micellar Aggregates ◽  
Vis Spectroscopy ◽  
Mechanism Of The Reaction

The oxidation of ethylene glycol by periodate (IO4-) was studied in different micellar aggregates of cetyltrimethylammonium bromide (CTABr) and dodecylamine (DA) by means of UV/Vis spectroscopy. The observed constant Ko was obtained by monitoring the disappearing of ethylene glycol with time at a suitable wavelength under pseudofirst condition. Addition of CTABr and DA inhibits the reaction rate while the kinetic behavior was explained on the association of one of the reactants with the micelles leaving the other reactant in the bulk solution (pseudophase model).

Preparation, cure behavior and properties of bismaleinides containing well defined oligo(phenylene sulfide) segments

1993 ◽  
Vol 5 (3) ◽  
pp. 213-218 ◽  
Author(s):  
F P Glatz ◽  
R M'ilhauptt
Keyword(s):  
Thermal Stability ◽  
Phase Transitions ◽  
Segment Length ◽  
Cross Linking ◽  
Cure Reaction ◽  
Reaction Phase ◽  
Cure Behavior ◽  
Eutectic Mixtures ◽  
Phenylene Sulfide

A family of bismaleimides (PPS-BMIs) containing flexible oligo(phenylene sulfide) (PPS) segments was prepared from the corresponding monodisperse diamine-terminated oligo(phenylene sulfide)s (PPS-DAs). PPS-BMIs and PPS-DAs formed eutectic mixtures which melted below 200 C. Upon heating above 200 C, chain advancement via Michaeltype addition of PPS.DA to PPS-BMI followed by cross-linking produced networks containing PPS segments. The influence of the PPS segment length on processing, cure reaction, phase transitions, and thermal stability was investigated.

Optimal Curing of Rubber Compounds with Reversion Type Cure Behavior

2000 ◽  
Vol 73 (1) ◽  
pp. 101-113 ◽  
Author(s):  
In-Su Han ◽  
Chang-Bock Chung ◽  
Jae-Woo Lee
Keyword(s):  
Kinetic Model ◽  
Optimization Problem ◽  
Numerical Algorithms ◽  
Optimization Procedure ◽  
Dynamic Optimization Problem ◽  
Cure Behavior ◽  
Cure Kinetic ◽  
Rubber Compounds ◽  
Simulation Results ◽  
Cure Temperature

Abstract A systematic procedure is presented for the optimal curing of rubber compounds showing reversion type cure behavior. First, a cure kinetic model is proposed that can explain the reversion and the induction period commonly found in the vulcanization of rubber compounds. The state of cure behavior is analyzed as a function of cure temperature and time on the basis of the derived kinetic model. Then, the problem of determining optimal cure temperature profile for a rubber slab in a simple cure press is addressed and formulated into a constrained dynamic optimization problem. Finally, numerical algorithms and simulation results are presented to demonstrate the proposed cure optimization procedure.

Study on a Characterization Method of Curing Rate of UV Curing System Based on Rheokinetics

2012 ◽  
Vol 262 ◽  
pp. 454-459
Author(s):  
Bei Qing Huang ◽  
Kai Yuan Luo ◽  
Xian Fu Wei ◽  
Ling Ya Gu ◽  
Mu Qun Yu
Keyword(s):  
Dynamic Modulus ◽  
Uv Light ◽  
Uv Curing ◽  
Polymerization Reaction ◽  
Curing Process ◽  
Performance Parameters ◽  
Cure Reaction ◽  
New Approach ◽  
Set Up ◽  
Nonlinear Kinetic

Curing rate is one of the most important performance parameters of UV curing system. During the curing process, curing degree is closely related to curing rate. Cross linking and curing degree of the system could be reflected by rheological characteristics. A method based on rheokinetics was used to characterize radical polymerization reaction which initiated by UV light. Changes of G’ (dynamic modulus) in every stage of curing process were real-time monitored by a rheometer equipped with UV curing accessory. The influence of varieties and contents of photo-initiators on curing process of polyester acrylates was studied. Associating conversion rate with dynamic modulus, a nonlinear kinetic equation was set up to describe the cure reaction. The results show that, this paper has put forward a method based on rheokinetics, to study the curing rate of UV curing system, and provided a new approach to study UV cure reaction.

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