2.2 MATRIX
Although the strength of composites depends primarily on the nature and type of reinforcement used. However a minor portion of the properties of composites depends on the matrix used. Naturally, reinforcements (fibres, whiskers, particulate, etc.) have limited properties and usage unless they are bonded together by matrix to form a bulk structure. This fabricated structure can then be used for several applications [R Jones, 1999].
Generally a matrix material is a component or constituent of a composite that forms the continuous phase of a composite. Primarily, the matrix portion of a composite plays the role of holding the reinforcements in position and also deform and distribute stress to the reinforcement depending on the mode
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The attractive mechanical properties of thermoplastics makes it suitable to be used in various disciplines (marine, aircraft, etc.). Thermoplastics are not cross-linked in their molecular structure hence contributing to high strength [Adjaottor, 2015]. Thermoplastics can be repeatedly softened and remoulded into other forms by heating. The high rate of recycling thermoplastics makes it convenient to be used in composite materials. Thermoplastics have a lot of advantages for engineering design applications. These advantages are high ductility, toughness, etc. Typical examples of thermosets include polyethylene (high or low density), polypropylene, nylon and acrylics. [Adjaottor, …show more content…
melting temperature (oC) 125 110
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2.2.2.2 Thermoset matrix
Thermosets are classes of polymers that are produced from a network molecular structure of primary covalent bonds. The structure of thermosets are crosslinked by application of heat and pressure and chemical reactions occurring at high temperature. Thermosets therefore cannot be reheated and reshaped into other forms as thermoplastics do. This limitation of thermoset makes them decline in usage due to the difficulty in recycling. The advantages of thermosets for engineering design are high thermal stability, high rigidity, resistance to creep and deformation load etc. [Alfred, 1999].
Table 2.2: Properties of some common thermoset matrix
Property polyester vinyl ester Epoxy
Density (g/cm3) 1.13 1.12 1.28
Tensile strength (MPa) 77 81 76
Flexural strength (MPa) 123 138 115
Flexural modulus (MPa) 2.96 3.72 3.24
Elongation at break (%) 4.5 5.0 6.3
Heat distortion temperature (oC) 71 104
Chemical bonding, also known as chemical reactions, are happening all around us. From cold packs we use on various injuries to the water we drink, they’re all results of chemical bonding. To be more specific, endothermic and exothermic reactions are both types of chemical reactions that are classified by the heat energy that is either released or absorbed when a reaction occurs. An example of an endothermic reaction would be an “instant cold pack”, which become chilled when activated. As for exothermic reactions, “hot packs” make great examples due to their significant temperature increase in just a few minutes.
Endothermic reactions absorb energy while exothermic reactions release it. 2.3 How is matter classified? pure substance - matter composed of only one kind of atom or molecule mixture - a collection or two of more pure substances physically mixed together homogeneous mixture - a mixture containing substances that are uniformly distributed heterogeneous mixture - a mixture containing substances that are not evenly distributed phase - any part of a system that has uniform composition and properties elements - the 109 simplest substances from which more complex materials are
If the independent variable changes then the results and outcomes of each testing done with the insulators will be different. The time intervals will also depend on which insulator is the best, as it can affect the structure of the material and how it conducts its temperature(s). If steel wool is made of fine strands of steel, and steel is a form of metal, metal is known to be a good conductor of heat because of the close packing of the metal ions in the lattice and the delocalised electrons that can carry kinetic energy through the lattice.
Introduction Heat is the form of energy, thermal energy, which flows between two substances due to their difference in temperature.1 The measurement of heat flow is called Calorimetry and the apparatus used to measure the heat flow (temperature change) for a reacting system is called a calorimeter. The calorimeter is well-insulated device that help to minimize the heat exchange between the system being observed and its surroundings. In this experiment, simple calorimeter, coffer cup calorimeter containing Styrofoam cups is used. Calorimeter contains a thermometer and a stirrer.3 Thermometer is typically inserted in the calorimeter to measure the change in the temperature that results from the reaction.
Based on the data found in the experiment, silicone has a Young’s modulus of 2.183 ± 0.654 MPa while neoprene has a Young’s modulus of 8.903 ± 3.847 MPa. Looking at these two values, the Young’s modulus for silicone is closer to the Young’s modulus of skin. The elastic toughness for skin was found to be 4.9 ± 1.5 MJ/m3 [3]. The values of elastic toughness for neoprene and silicone were 0.0469 ± 0.0252 MJ/m3 and 1.813 ± 0.5428 MJ/m3, respectively. Although these values are not exactly in line with the values found for skin, the values for silicone were closer to the literature values for skin, making silicone the better skin replacement option overall.
The cotton letterman jacket is potent enough to absorb moisture and help you in keeping fresh at all times. 6. Synthetic Fibres: Popular synthetic fibres such as nylon and polyester are widely used today because they are inexpensive and durable. But the downside to it is that it doesn't absorb moisture in the body. So, you may feel all sweaty in summer months.
Our objective was to pick the best chemical to be used in a hand warm. This chemical had to be cheap, relatively safe, and must raise the temperature by 20oC and no more. We add 6 different chemicals to water we record the inshell temperature and then add one a the 6 chemicals to the water and record the temperature change of the water. We also add cold water hot water together to find how much heat would escape the calorimeter. We found that the calorimeter absorbed 71.1J/oC. Then this information to calculate the energy that was released by all of the chemical reaction.
While performing this lab, endothermic reactions apply because it’s a “chemical reaction that absorbs heat from its environment. The absorbed energy
Thermal energy may be exchanged to foods through convection, radiation or conduction. Heat then travels via foods by conduction. Only thermal is transferred cold is simply the absence of thermal, so cold cannot be transferred from one substance to another. Convection Convection refers to the exchange of thermal via a fluid, which may be gas or liquid.
Synthetic molecules Student: Omar Moghrabi Section: 9A Teacher: Bader Al Saidi introduction: Many products in our everyday lives, such as plastic containers and bags, to medicine tablets, and even water bottles have one thing in common, and that is because they are all mad of synthetic molecules / chemicals. These chemicals play a huge role in our community because people really rely on the products that are made by them for storage, medicinal problems, cleaning, and working. One of the various types of synthetic molecules is low-density polyethylene (or LDPE for short) is used for making trays, plastics, bottles etc. This essay will talk about low-density polyethylene and the synthetic molecules in general, discussing there advantages
Most people can guess that the handwarmers we use so often, especially during the colder seasons, is warm as a result of chemical reactions. How is it, however, that with a simple shake, it awakens the chemicals to suddenly react with each other? Which chemicals are the best at giving off heat during reaction? How do they actually work? Our recent study of thermodynamics has led me to become curious about those little helpful packages of warmth.
For best results, choose one that provides ample protection against external factors while allowing air to
Finding alternatives may be difficult because PVC has a lot of greater features such as being cost efficient, durable, scratch resistant, and formable. The alternative of thermoplastic urethane (TPU) is twice the price, which will increase cost significantly for the company. Herman Miller as a company must not only work to incorporate their new C2C design protocol but simultaneously keep good relationships with suppliers and keep cost
Introduction: The objective for the lab was to determine properties of materials by using a tension test. The properties that were determined was Young’s Modulus, ultimate tensile strength, and yield strength. Three aluminum alloys were tested. The first was the AA 2024 , which is high strength used in aerospace applications.
The former can be heated and shaped and are used in the modern world many times, containing everything from children's toys to toilet seats. Because they can be melted down and reshaped, thermoplastics are usually recycled. Thermoset plastics can only be heated and shaped once, after which the molecular changes mean they are “cured,” retaining their shape and strength even when they are subjected to intense heat and the pressure. Thermoset plastics plays a vital part in our modern world.