2. B. Bakelite and melamine both are thermosetting plastics. Pupils can then try the ‘quiz time’ questions to test their thermosetting plastic knowledge. Question 14. Molded Bakelite forms in a condensation reaction of phenol and formaldehyde, with wood flour or asbestos fiber as a filler, under high pressure and heat in a time frame of a few minutes of curing. 3. Write two important properties of bakelite. Q. >urea-formaldehyde resin, and melamine-formaldehyde resin—are widely used as adhesives in plywood and other structural wood products. searches to solve its rigidity problem. For example, Bakelite jewelry is more rare than, say, … Answered By 12. In the growing consumer market of the 1930s and after, Bakelite faced competition from other thermosetting resins such as urea formaldehyde and melamine formaldehyde and from new thermoplastic resins such as cellulose acetate, polyvinyl chloride, polymethyl methacrylate, and polystyrene. We'll discuss whether it's safe to use and any risks. Question 25. 54) Thermopalstics can be softened by heat but thermosetting plastics cannot be softened by heat. Tamilnadu Samacheer Kalvi 7th Science Solutions Term 3 Chapter 3 Polymer Chemistry Answer: (d) Bakelite. Q. Classify the following into thermosetting and thermoplastics-combs, bakelite, melamine, toys. 10. Ans. Preview this quiz on Quizizz. MCQ Questions for Class 12 Chemistry with Answers were prepared based on the latest exam pattern. Why are the chemicals in the laboratory stored in plastic containers ? Answer. (b) Melamine (c) PET (d) Polyester. 11. 15. D. Bakelite is a thermoplastic whereas melamine is a thermosetting plastic. Melamine formaldehyde (MF) resins MF resins have similar properties to UF resins, but they are tougher and more thermally stable and chemically resistant. 29-5D Urea-Methanal and Melamine Resins. (i) It is a poor conductor of electricity. Bakelite is a thermosetting plastic, it cannot be molded again whereas Melamine, being a thermoplastic, can be molded any number of times adn reshaped. Answer. Bakelite is an item a jewelry collector should keep an eye out for considering how prices have risen over the last few decades. It can be explained as follows : both the two plastics are made up of long chain molecules called polumers. Explain the difference between thermoplastics and thermosetting plastics. False 8. Bakelite's molding process had a number of advantages. Bakelite is a poor conductor of electricity. J. Bentley, in Paint and Surface Coatings (Second Edition), 1999. 14. For example, melamine has an annual replacement rate of around 10 to 20%, whereas china has a replacement rate between 50 and 150%. Like cyanamide, it contains 67% nitrogen by mass, and its derivatives have fire retardant properties due to its release of nitrogen gas when burned or charred. (a) PVC (b) Polythene (c) PET (d) Bakelite. A. Melamine is a thermoplastic whereas bakelite is a thermosetting plastic. 21. Bakelite is used for making electrical switches and switchboards because it is a poor conductor of heat and electricity. False 3. False 2. (ii) It is heat resistant. The classic example is Bakelite, the phenol/formaldehyde-based resin invented by the Belgian chemist Baekeland in the early 20th century. False 10. Bakelite is the first synthetic plastic and is known as a “material of thousand uses” due to its versatile applications. Bakelite and melamine are examples of thermosetting plastic. Bakelite is a condensation polymer that requires two monomers - phenol and formaldehyde. Today, part of the reason why Bakelite items are collectibles, are because of the fine artisanship. These cannot be re-melted. The formation process of these two types of plastics also differs. There are several variables in the method of polymerization, depending on the properties desired. The result is a hard plastic material. Hold another type of plastic you have identified in one hand, and a piece you know to be Bakelite of approximately the same size in the other. Answer: 1. Polythene and PVC are some of the examples of thermoplastics. (a) Saucepan handles (b) Electric plugs/switches/plug boards. Example : Polyethene, Polyvinyl chloride (PVC) etc. Thermosetting plastic: Plastics which do not get deformed or softened on heating when mold once, are called thermosetting plastics. It came in several colors, including translucent and marbled shades by the 1950s. Modern non-stick cookware and the flat end of an electric iron has a coating of a polymer. In the first half of the 20th century they were made into very important plastics such as Bakelite and Beetleware.… Then try the ‘ quiz time ’ Questions to test their thermosetting plastic the following into thermosetting and thermoplastics-combs bakelite. Flat end of an electric iron has a coating of a polymer two types of plastics, like celluloid one... 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