Abstract
polymeric resins are micro-molecules that by increasing the temperature (for overcoming the activation energy) begin to form covalent bonds and finally create a structure of thermoset block. Curing reactions rate increase by increasing of system temperature based on Arrhenius function. curing reaction of polymeric resin are exothermic. This means that by increasing the degree of reaction progress, accumulated heat increases the temperature of the system. Thus, with the progress of curing reactions, the released heat increases the temperature of the system and increases the curing rate. So, the temperature of curing systems of polymeric resin is not constant and it is needed to predict and control these changes with the help of computer simulation. In this article, MeasSoft has investigated the curing behavior and temperature changes of a type of polymeric resin in a cylindrical mold.
Keywords: Differential Scanning Calorimetry (DSC), SPI Test, Curing kinetics, Simulation, Heat, Temperature
Abstract
Thermoset resins and rubbers are molecules that are polymerized or cured by thermal energy. After curing, these materials form a three-dimensional network of covalent connections and be converted to a non-transfiguration rigid product. Nowadays developing of simple processing methods and technological advancements makes extensive use of them in the industry.
Polymerization of the resins or vulcanization of the rubbers are exothermic reactions. On the other hand, physical properties of the thermoset bulk are dependent of reaction conversion and curing conditions. Thus the curing reaction should be a controllable and predictable process to achieve a product with tailoring and desiring properties.
Also thermal decomposition process of polymeric materials is an important and applicable process in many industries such as flame resistance for use in the aerospace industry such as spacecraft, rockets, missiles and etc. thermal decomposition process of polymeric materials causes the three-dimensional network of covalent connections break and lots of released gaseous product with a porous char mass remains.
Therefore, we need to be able to model and simulate curing and decomposition process of polymeric systems so that we can offer a mathematical equation that predict and model these important reactions.
The most common methods for investigation of curing Kinetics of resins, vulcanization of rubbers and decomposition of polymeric systems are DSC test, TGA test and ODR test respectively. Kinetics models and calculation path of all of these methods are similar and only their test methods are different.
Keywords: activation energy, Kinetics parameters, curing, vulcanization, decomposition, gel time, n-order, autocatalytic, DSC, TGA, ODR, Kissinger, Ozawa, Friedman, Modeling, Simulation, rubber, resin, polymer
Abstract
The tensile machine test assumes that the cross-sectional area of the sample does not change by applying the force. Therefore, the apparent stress-strain diagram differs from the real stress-strain diagram. So the real yield point on apparent diagram is not an accurate point. in this article we try to calculate the real stress-strain diagram and real yield point form apparent diagram.
Keywords: True Stress, Real Stress, Nominal Stress, Engineering Stress, Apparent Stress, Tensile Test, ductile, yield point, plastic, deformation
Abstract
Polymers are one of the most important materials used in industry. No other material in the world can provide the properties of polymers. The main properties of polymers are influenced by their molecular weight. Various methods have been proposed to evaluate the molecular weight of polymers. Most of these methods require a lot of equipment and cost. One of the simplest and cheapest ways to evaluate the molecular weight of polymers is to measure their intrinsic viscosity. In fact, the amount of the intrinsic viscosity is a criterion for the amount of molecular weight. The intrinsic viscosity is obtained by the drainage time of the polymer solution in a capillary tube in compared to pure solvent. So far, many formulas have been proposed for obtaining the intrinsic viscosity of polymeric materials by drainage time data. In this article, some of the most important of these formulas are presented.
Keywords: intrinsic viscosity, capillary viscometer, relative viscosity, specific viscosity, single-data, multi-data
