10. Bakelite jewelry became immensely popular in the 1920s as an affordable and attractive replacement for other materials. The result is a hard plastic material. (ii) It is heat resistant. Ans. Answer: Melamine is a versatile material. Bakelite and melamine are thermoplastics. 11. Melamine is resistant to fire and is hence used for making utensils. True 9. Question 14. Bakelite feels heavier when compared to some other types of plastics, like celluloid as one example. False 6. Today, formica and medium density fiberboard (MDF) are still made by mixing bakelite with paper pulp or … Bakelite's molding process had a number of advantages. Example : Bakelite, Melamine etc. Thermoplastic: Plastics that can be deformed easily upon heating and can be bent easily. Thermosetting plastic: Plastics which do not get deformed or softened on heating when mold once, are called thermosetting plastics. Identify the name of the polymer. >urea-formaldehyde resin, and melamine-formaldehyde resin—are widely used as adhesives in plywood and other structural wood products. 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. The classic example is Bakelite, the phenol/formaldehyde-based resin invented by the Belgian chemist Baekeland in the early 20th century. Today, part of the reason why Bakelite items are collectibles, are because of the fine artisanship. If plastics are burnt, they evolve oxygen gas. Question 13. 2. 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. Examples: PVC and Polythene are used for manufacturing combs, toys, car grills and various type of containers. Plastics are corrosive in nature. Q. Bakelite is a poor conductor of electricity. In the first half of the 20th century they were made into very important plastics such as Bakelite and Beetleware.… False 8. The market value is extremely high, due to the retro feel and limited quantities of certain products. We have provided Polymers Class 12 Chemistry MCQs Questions with Answers to help students understand the concept very well. For example, melamine has an annual replacement rate of around 10 to 20%, whereas china has a replacement rate between 50 and 150%. 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. Bakelite is a man-made (synthetic) material while Melamine occurs naturally (is organic). 54) Thermopalstics can be softened by heat but thermosetting plastics cannot be softened by heat. Answer: 1. Hence, option C is correct. Q. Synthetic fibres are moth and insect resistant. Identify the type of plastic that can best be used to make electrical switches. Example: Bakelite, melamine, etc. Bakelite definition, a brand name for any of a series of thermosetting plastics prepared by heating phenol or cresol with formaldehyde and ammonia under pressure: used for radio cabinets, telephone receivers, electric insulators, and molded plastic ware. (a) Saucepan handles (b) Electric plugs/switches/plug boards. 3. (i) It is a poor conductor of electricity. Bakelite is a condensation polymer that requires two monomers - phenol and formaldehyde. D. Bakelite is a thermoplastic whereas melamine is a thermosetting plastic. You will often notice the heavier feel of Bakelite. B. Bakelite and melamine both are thermosetting plastics. Video Explanation. Example : Polyethene, Polyvinyl chloride (PVC) etc. We'll discuss whether it's safe to use and any risks. Consider the weight of a piece of plastic jewelry. Why are the chemicals in the laboratory stored in plastic containers ? The formation process of these two types of plastics also differs. what  are the wide range of synthetic or semi-synthetic organic compounds that are malleable and so can be molded into solid objects 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. In 1927 the Bakelite patent expired. 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. 11. 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. Answer: Thermosetting – bakelite, melamine Thermoplastics – combs, toys. 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. MCQ Questions for Class 12 Chemistry with Answers were prepared based on the latest exam pattern. Question 25. Polythene and PVC are some of the examples of thermoplastics. 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. Two example of thermosetting plastics are : Bekalite and melamine. Jammu & Kashmir has banned the use of plastic bags. For example, glycerol [5], isocyanate [6] as well as substituted melamine [7] had been added into MF resin to improve its flexibility. Check the below NCERT MCQ Questions for Class 12 Chemistry Chapter 15 Polymers with Answers Pdf free download. 13. For example, Bakelite jewelry is more rare than, say, … Answer: (d) Bakelite. It can be explained as follows : both the two plastics are made up of long chain molecules called polumers. It is also heat resistant and used for making electrical switches, handles of various utensils, etc. Classify the following into thermosetting and thermoplastics-combs, bakelite, melamine, toys. Q. It came in several colors, including translucent and marbled shades by the 1950s. True 7. Melamine formaldehyde (MF) resins MF resins have similar properties to UF resins, but they are tougher and more thermally stable and chemically resistant. 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. Preview this quiz on Quizizz. Answer. Ans. Bakelite definition: 1. a brand name for a type of hard plastic used especially in the past: 2. a brand name for a type…. Plus, melamine is relatively resistant to scratch marks from forks, knives, and other utensils. It was the first truly synthetic plastic and was developed and patented by Leo Baekeland in 1907. True 11. (a) PVC (b) Polythene (c) PET (d) Bakelite. Bakelite -- Bakelite is the most common material used in older American-made plastic Mah Jongg tiles. Given one example of each. It resists fire and can tolerate heat better than other plastics. Question 7: Explain why the following are made of thermosetting plastics. Bakelite is a thermosetting plastic, it cannot be molded again whereas Melamine, being a thermoplastic, can be molded any number of times adn reshaped. Write two important properties of bakelite. 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. There are several variables in the method of polymerization, depending on the properties desired. Tamilnadu Samacheer Kalvi 7th Science Solutions Term 3 Chapter 3 Polymer Chemistry Bakelite is a thermosetting phenol formaldehyde resin, formed from a condensation reaction of phenol with formaldehyde. 14. 20. Explain the difference between thermoplastics and thermosetting plastics. Answer: (b) Melamine. Bakelite is used for making electrical switches and switchboards because it is a poor conductor of heat and electricity. 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. Melamine / ˈ m ɛ l ə m iː n / is an organic compound with the formula C 3 H 6 N 6.This white solid is a trimer of cyanamide, with a 1,3,5-triazine skeleton. 12. For example: - Bakelite and Melamine. Learn more. True 5. J. Bentley, in Paint and Surface Coatings (Second Edition), 1999. 12. See more. False 2. 21. 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