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. 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. Write some uses of Bakelite. You will often notice the heavier feel of Bakelite. In 1927 the Bakelite patent expired. 54) Thermopalstics can be softened by heat but thermosetting plastics cannot be softened by heat. Classify the following into thermosetting and thermoplastics-combs, bakelite, melamine, toys. Explain the difference between thermoplastics and thermosetting plastics. Students can Download Science Chapter 3 Polymer Chemistry Questions and Answers, Notes Pdf, Samacheer Kalvi 7th Science Book Solutions Guide Pdf helps you to revise the complete Tamilnadu State Board New Syllabus and score more marks in your examinations. For example: - Bakelite and Melamine. Preview this quiz on Quizizz. C. Bakelite and melamine both are thermoplastics. We have provided Polymers Class 12 Chemistry MCQs Questions with Answers to help students understand the concept very well. Question 7: Explain why the following are made of thermosetting plastics. Bakelite is a man-made (synthetic) material while Melamine occurs naturally (is organic). (ii) It is heat resistant. (i) It is a poor conductor of electricity. Check the below NCERT MCQ Questions for Class 12 Chemistry Chapter 15 Polymers with Answers Pdf free download. Look for models … It came in several colors, including translucent and marbled shades by the 1950s. Answer: Thermosetting – bakelite, melamine Thermoplastics – combs, toys. 11. what  are the wide range of synthetic or semi-synthetic organic compounds that are malleable and so can be molded into solid objects 2. Melamine is a compound used in some plastic products, such as dishes, utensils, and more. Bakelite is a poor conductor of electricity. The formation process of these two types of plastics also differs. Key Difference – Bakelite vs Plastic Plastic and Bakelite are both organic polymers, having a very large molecular weight though there exists a difference between the two based on their properties and usage. It can be explained as follows : both the two plastics are made up of long chain molecules called polumers. Video Explanation. 29-5D Urea-Methanal and Melamine Resins. A. Melamine is a thermoplastic whereas bakelite is a thermosetting plastic. Melamine is resistant to fire and is hence used for making utensils. (a) Saucepan handles (b) Electric plugs/switches/plug boards. Bakelite is used for making electrical switches and switchboards because it is a poor conductor of heat and electricity. 13. Bakelite and melamine are examples of thermosetting plastic. True 11. Plastics are corrosive in nature. Plus, melamine is relatively resistant to scratch marks from forks, knives, and other utensils. Consider the weight of a piece of plastic jewelry. Example : Polyethene, Polyvinyl chloride (PVC) etc. Identify the type of plastic that can best be used to make electrical switches. Answer: (d) Bakelite. 14. Identify the name of the polymer. False 3. Answer: Melamine is a versatile material. 15. Today, formica and medium density fiberboard (MDF) are still made by mixing bakelite with paper pulp or … Bakelite definition: 1. a brand name for a type of hard plastic used especially in the past: 2. a brand name for a type…. Q. The result is a hard plastic material. Compared to bakelite, melamine is lighter and more elastic and therefore can be used with thinner objects, for example, in games and models, as well as for creating bijoux and accessories for clothes. Examples: PVC and Polythene are used for manufacturing combs, toys, car grills and various type of containers. Answer. Bakelite is a thermosetting plastic, it cannot be molded again whereas Melamine, being a thermoplastic, can be molded any number of times adn reshaped. True 5. Melamine formaldehyde (MF) resins MF resins have similar properties to UF resins, but they are tougher and more thermally stable and chemically resistant. 21. Bakelite and melamine are thermoplastics. Synthetic fibres are moth and insect resistant. 12. It was made from a mixture of phenol (carbolic acid) and formaldehyde. 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. Bakelite is a thermosetting phenol formaldehyde resin, formed from a condensation reaction of phenol with formaldehyde. D. Bakelite is a thermoplastic whereas melamine is a thermosetting plastic. See more. Ans. J. Bentley, in Paint and Surface Coatings (Second Edition), 1999. >urea-formaldehyde resin, and melamine-formaldehyde resin—are widely used as adhesives in plywood and other structural wood products. Learn more. Modern non-stick cookware and the flat end of an electric iron has a coating of a polymer. Question 13. (b) Melamine (c) PET (d) Polyester. For example, Bakelite jewelry is more rare than, say, … True 9. T h e r m o p l a s t i c s: These are the plastics which get deformed easily on heating and can be bent easily. 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. Bakelite is used for making electrical switches whereas melamine is used for floor tiles. Bakelite is the first synthetic plastic and is known as a “material of thousand uses” due to its versatile applications. 20. Candidates can download NCERT Exemplar Class 12 Chemistry Chapter 15 from this page. It was the first truly synthetic plastic and was developed and patented by Leo Baekeland in 1907. Bakelite is a condensation polymer that requires two monomers - phenol and formaldehyde. Answer: (b) Melamine. There are several variables in the method of polymerization, depending on the properties desired. Answer. The classic example is Bakelite, the phenol/formaldehyde-based resin invented by the Belgian chemist Baekeland in the early 20th century. Thermoplastic: Plastics that can be deformed easily upon heating and can be bent easily. False 2. Q. False 6. Example : Bakelite, Melamine etc. Bakelite and melamine are the examples of thermosetting plastics. Question 25. Answer: Plastics are non-reactive, so they can be used for storing chemicals. 10. Pupils can then try the ‘quiz time’ questions to test their thermosetting plastic knowledge. Thermosetting plastic: Plastics which do not get deformed or softened on heating when mold once, are called thermosetting plastics. Tamilnadu Samacheer Kalvi 7th Science Solutions Term 3 Chapter 3 Polymer Chemistry Example: Bakelite, melamine, etc. Answered By 12. (a) PVC (b) Polythene (c) PET (d) Bakelite. Why are the chemicals in the laboratory stored in plastic containers ? searches to solve its rigidity problem. Today, part of the reason why Bakelite items are collectibles, are because of the fine artisanship. Given one example of each. 33. Polythene and PVC are some of the examples of thermoplastics. Jammu & Kashmir has banned the use of plastic bags. MCQ Questions for Class 12 Chemistry with Answers were prepared based on the latest exam pattern. For example, melamine has an annual replacement rate of around 10 to 20%, whereas china has a replacement rate between 50 and 150%. Thermosetting polymers : These are semifluid substances with low molecular masses which when heated in a mould, undergo change in chemical composition to give a hard, infusible and insoluble mass. False 8. It is also heat resistant and used for making electrical switches, handles of various utensils, etc. We'll discuss whether it's safe to use and any risks. True 4. It resists fire and can tolerate heat better than other plastics. For example, glycerol [5], isocyanate [6] as well as substituted melamine [7] had been added into MF resin to improve its flexibility. True 7. The market value is extremely high, due to the retro feel and limited quantities of certain products. B. Bakelite and melamine both are thermosetting plastics. Bakelite feels heavier when compared to some other types of plastics, like celluloid as one example. Answer: 1. Hence, option C is correct. Bakelite's molding process had a number of advantages. Bakelite is an item a jewelry collector should keep an eye out for considering how prices have risen over the last few decades. MF resins are used for higher end applications like laminates for countertops and cabinets and surface coatings for automobiles that require a binder with good cosmetic characteristics. Question 14. As we all know, emulsifier can reduce the interfacial tension and increase the contact area between foaming agent and MF resin which is benefit to foaming. Ans. Syntheses of a number of polymers are based on condensation of methanal with amino compounds by mechanisms at least formally analogous to those involved in the preparation of Bakelite resins. If plastics are burnt, they evolve oxygen gas. In the first half of the 20th century they were made into very important plastics such as Bakelite and Beetleware.… The exemplar has been provided by the National Council of Educational Research & Training (NCERT) and the candidates can check it from below for free of cost. Q. 11. These cannot be re-melted. Bakelite jewelry became immensely popular in the 1920s as an affordable and attractive replacement for other materials. Authentic bakelite jewelry can sell for thousands of dollars, so it's important you learn how to tell the difference between genuine and imposter plastic jewelry. 3. Ans.Bakelite and melamine. False 10. Bakelite -- Bakelite is the most common material used in older American-made plastic Mah Jongg tiles. 2.10.4 Uses. 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