Polymer- Differential Scanning Calorimetric (DSC)

Its very use full for Eng....

1. Polymer Chemistry…………….. Dr. R.TAMILARASAN . M.Sc., Ph.D. Assistant Professor Department of Chemistry, Vel Tech Multi Tech Dr Rangarajan Dr Sakunthala Engineering College, Chennai - 62 . Tamil Nadu , India 1

2. Outline of the chapters……… Determination by differential scanning calorimetric Polymer processing and techniques Outline of moulding techniques compression, 2 injunction, extrusion and blow moulding, Compounding techniques

3. 3 Differential Scanning Calorimetric (DSC )

4. Introduction………… Need to know about the calorimeter, it is one who measures the heat in or out of the sample. and differential calorimeter is one who measures the heat of the sample relative to the reference. This technique is used to study what happens to polymers/samples upon heating. It is used to study thermal transitions of a polymer/sample (the changes that take place on heating). 4 It is a technique in which the energy necessary to establish a zero temperature difference between the sample & reference material is measured as a function of temperature. The differential scanning calorimeter does all of the above functions and heats the sample with the linear temperature. Both the sample and reference are maintained at nearly the same temperature throughout the experiment in DSC.

5. 5 During heating two types of reactions can be take place one is the endothermic and the other is the exothermic. Endothermic reaction: Here, sample & reference material are heated by separate heaters in such a way that their temp are kept equal while these temp are increased or decreased linearly. Exothermic reaction: If sample absorbs some amount of heat during phase transition then reaction is said to be endothermic. In endothermic reaction more energy needed to maintain zero temp difference between sample & reference. E.g. Melting, boiling, sublimation, vaporization if sample released some amount of heat during phase transition, then reaction is said to be exothermic. In exothermic reaction, less energy needed to maintain zero temp difference between sample & reference. E.g crystallization, degradation, polymerization.

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8. 8 There are two pans, In sample pan, polymer is added, while the other, reference pan is left empty. Each pan sits on top of heaters which are controlled by a computer The computer turns on heaters, and let them heat the two pans at a specific rate. The computer makes absolutely sure that the heating rate stays exactly the same throughout the experiment. Why heaters don’t heat at the same rate? The simple reason is that the two pans are different. One has polymer in it, and one doesn't. The polymer sample means there is extra material in the sample pan. So the heater underneath the sample pan has to work harder than the heater underneath the reference pan. It has to put out more heat. Having extra material means that it will take more heat to keep the temperature of the sample pan increasing at the same rate as the reference pan.

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39. 39 Glucose Biosensor………… A biosensor is an analytical device used for detecting the chemical substance that combines the biological component with a physiochemical detector. Glucose biosensor is a device that measures the concentration of glucose in diabetic patients by means of a sensitive protein glucose oxide. It is based on the that the immobilized glucose oxide catalyses the oxidation of β -D-glucose by molecular oxygen producing gluconic acid and hydrogen peroxide. Glucose Biosensor is used for the testing of glucose in blood. It composed of glucose meter and test strips. On cooling it gets solidified. Then the mould is opened and the article is removed.

40. 40 A glucose meter is an electronic device used for measuring the blood glucose. A small drop of blood is placed on a disposable test strip which interfaces with digital meter . Within several seconds the level of blood glucose will be shown on the digital display . H 2 O 2 Oxidizes at Pt electrode. The no of e - s transfers at electrode surface is directly proportional to the number of glucose molecules present in the blood. Concerns of test strips: It has silver anode and Pt cathode The electrodes are immersed in electrolyte It is surrounded by Teflon membrane effect In between Teflon membrane and cellophane membrane

41. 41 High Speed Flexibility Low cost Application Manufacturing bottle caps, buckets, mugs, chairs etc… Advantages

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45. 45 Polymers for LED (Light Emitting Diodes ) or Poly Light Emitting Diodes (P-LED ) or Light Emitting Polymer (LEP ) : In Light Emitting Diodes (LEDs ) polymers is used as the semi conducting material . Polymers LEDs have number of inherent qualities. They are enable to display full spectrum color. High brightness at low voltages, Glares free viewing, long operating lifetimes. Thus it can be used for many applications such as flexible displays, indoor lighting and medical technology applications. Polymer LEDs are produced by sandwiching electroluminescent polymers between a metal cathode and a transparent anode. Polymer LEDs are produced by sandwiching electroluminescent polymers between a metal cathode and a transparent anode.

46. 46 When the anode (Indium Tin Oxide) and cathodes (Aluminum) are connected to the external voltage, electrical current flows from the cathode to anode through the polymer layer. It passes e - s to emissive layer and removing e - s from the conducting layer and recombine with e - s. As the e - s drop into the holes they release their extra as light.

47. 47 Advantages Very efficient Light weight Thin and flexible Smooth brightness Disadvantage Emitter part is sensation to oxidation and humidity P-LED have short lifetime at high temperature Application Used as display in mobile phones, Laptop, TVs Used in car bumpers. Used in e-news paper(future technology )

48. 48 Polymers for LCD (Liquid Crystal Display ) or Poly Liquid Crystal Display (P-LCD ) :

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50. 50 The liquid crystal are placed in between two polymers layers. The LCDs glass is coated with silicon dioxide to polarize the light. The LCD glass is made up of borosilicate. Transparent electrode are made with a layer of ITO (Indium Tin Oxide ). When electric current is applied to the liquid crystal molecules, the molecules tend to entrust. As a result the light is allowed to pass through the polarized glass to a particular area of LCD. Thus the particular area becomes dark and the image reflected on the glass display.

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