Dissertation
To receive a Master's degree
Polymer Engineering
April 2013
Abstract
Today, the topic of energy and energy saving in all fields, even in homes, is one of the most important concerns of mankind. A lot of energy is wasted through household use on cold winter days. Polyurethane insulations have the ability to preserve energy during winter and summer and against heat and cold.
Dangers caused by fire as well as dangers from toxic gases such as carbon monoxide and smoke, one of the disadvantages of using polymer and plastic materials is the delay of ignition in polyurethane by adding or placing a special halogen element in its structure. The use of halogenated materials, in addition to having advantages, has disadvantages, such as it can be dangerous from an environmental point of view, while a high amount of it is needed in the composition to be effective (about 60%), which can cause a drop in mechanical properties.
Therefore, the use of nanoclay increases the contact surface of particles due to the reduction in size from micro size to nano size. Increasing the contact surface leads to a decrease in the amount of material required to achieve desired properties. The presence of materials with a large contact surface can cause a change in the degradation path and thus affect the amount of polymer heat release. In the end, the use of nano-sized materials can cause the formation of a layer that prevents the movement of unstable materials during degradation and increases the production of charcoal. The simultaneous use of nanoclay and flame retardant will create a synergistic effect and the resistance to ignition will increase. In the present project, first composite and nanocomposite samples using a polyol and isocyanate along with modified nanoclay and urea condensate flame retardant; As a new flame retardant compatible with polyurethane and clay; was prepared and then the thermal behavior was established and the influence of the two additives Clausite B30 and Urea Condensate on the properties of flammability, resistance and thermal stability was investigated based on TGA and DSC thermal tests and finally, kinetic parameters and specific heat capacity and heat of decomposition were obtained from the results obtained from the above analyses. Also, in the presented model, by simultaneously solving the three equations of continuity and kinetic and heat transfer along with the initial and boundary conditions, the mass change process and other thermal properties related to temperature are predicted and obtained with practical results; It has been compared. Keywords: modeling, thermal response, kinetic model, nanocomposite, polyurethane
A model is a kind of simplification of reality and can present real or mental things from a specific domain. A good model includes effective elements and removing ineffective elements that are not directly related to the process or that increase the complexity of the model. Each system may be examined from different aspects by different models.
Generally, modeling leads to a better understanding of the system's behavior, the model will allow specifying the structure and behavior of the system even before construction. As a result, it will give us the possibility to fix the disadvantages of the system even before production; Which of course will save a lot of money and time. By understanding the behavior of the system, it is possible to control the system and its process, and with a better understanding of the system, system risk management and referring to the methods and changes applied to the system will be documented. In fact, it can be said that the model shows a summary of reality. In other words, the representation of generalities or the physics of an object or system from a specific point of view is called a model..
Modelling; The process of creating and choosing a model are called modeling. Models have various types (such as physical, mathematical, numerical, software, etc.) and have diverse and abundant vital applications in all fields of science and technology. Converting a physical concept into mathematical language is a type of modeling. The simpler the concepts of the mathematical language used in it, the more valuable the modeling is. In modeling, first the components of the real environment are selected and according to the intended purpose of the modeling, characteristics are extracted from each of the real components, that is, an artificial entity is made for each of the components of the real environment. And by establishing a relationship similar to the relationship of real components, among artificial entities, the real environment is modeled. So, it can be said that the purpose of modeling can be two things:
Knowledge[1]
It expresses only one aspect of modeling and that aspect is knowledge. That is, in modeling similar to the above-mentioned modeling, the purpose of modeling is only to know the environment of the model. Explanation [2] Another aspect of modeling is explanation. That is, sometimes to introduce and present the characteristics of a real entity, a model of it is presented. A geographical map is a good example that considers this aspect of modeling.
Based on the definition of the problem, modeling considers one or both goals.
Now we come to the question of what is the difference between modeling and simulation?
The answer is that modeling is the first step of simulation. In simulating the behavior of a system, we want to obtain it based on a scenario, which either cannot be obtained based on mathematical relationships or is very complicated.
Based on the defined scenario, the behavior is modeled and then the model is validated [3], and then the behavior of the system is predicted and simulated based on the scenario.
What is discussed in this work; according to seasons; They are: flame retardant composites, ignition properties of polymer nanocomposites, polyurethane, modeling the thermal response of the composite in the flame, and finally, the main part in which the preparation and investigation of the polyurethane/nanoclay/urea condensate nanocomposite was first discussed, and then the discussion of the thermal response modeling of the sample and investigation of the one-dimensional heat transfer behavior and the relationship between temperature and mass changes in the polymer composite made of Polyurethane/nanorase/urea condensate will be paid. An overview of the conducted researches
2-1 Flame retardant composites[4]
2-1-1 Introduction
In this section, we will have a general look at the methods of adding and optimizing the flame retardancy properties in fiber-reinforced composites. The methods used are extremely diverse and different. Simple alloying additives with polymer matrix or heat-resistant coatings[5], chemical methods of modifying the composite matrix whose surface becomes instumescence with heat. Also, methods to improve thermal stability and fire resistance of organic fibers used in composites have also been specified. The usual method to reduce the flammability of the composite is to add internal fillers (such as talc, silica) or thermally active fillers (such as hydrated oxides [6]) to the polymer matrix. Types of fillers, their ignition delay mechanism and their efficiency when used in composite materials will be described. After that, the modification of the chemical structure of organic polymers to improve the flammability resistance will be explained by relying on the ignition delay mechanisms and flame interaction properties in phosphorus, chlorine and boron polymers. Some of the mentioned methods for delaying ignition have been used for hundreds of years to reduce ignition in clothing fabric and wood, and recently in polymers and polymer composites. Other methods have been presented in the last 10 to 50 years. Several new methods are also being completed and improved to reduce flammability and offer a great perspective for delaying the ignition of composites.