(a) melamine common thermosetting polymers are bakelite, melamine-formaldehyde resin and urea formaldehyde resin. Which of the following statements is true for rayon? (c) large molecules made by joining many small molecules together Nylon, rayon, acrylic, terene and polycot are synthetic fibres. They become soft only the first time; they become hard. They are not infected by bacteria or fungus and are resistant to insects. (a) Annealing is the process by which glass is cooled and made tougher. 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We provide a total manufacturing solution that covers planning, molding, decorating and processing. Even though biodegradable plastics have been developed by scientists, they are costly and are not used on a large scale. Choose the thermoplastics and thermosetting plastics from the following: Melamine, Polythene, Bakelite, Polyvinyl chloride. Synthetic condensation polymers have a wide array of household, industrial, commercial, and medical uses … 3. Melamine is a thermoseting plastic which is resistant to fire and can tolerate heat better than other plastics. giving reasons. (b) The odd one is polycot. (b) they can be moulded into any shape Ans: The full form of PVC is ‘ Polyvinyl chloride’ PVC is a thermoplastic. Such plastics are called thermosetting plastic. Rewrite the false ones correctly. (a) False As wood contains huge amount of cellulose, rayon (synthetic fibre) is prepared chemically from wood pulp (cellulose). (b) It is obtained from wood containing large amount of cellulose. It is not a polyester synthetic fibre, while dacron, terene and terylene are polyester synthetic fibres that are manufactured from petroleum products. (d) they can coloured by adding pigments. (c) they do not conduct heat or electricity. Soln: Answer is (a) Melamine. Which of the following is a thermosetting plastic? Name the following: Recycling of Plastic. Phenol Formaldehyde Resin Powder Heat Resistance for Brake Pads Product description . It is a blended fabric, but rayon, nylon and acrylic are not. At home, when she burnt a small piece of fibre from the sweater, it smelled like burning plastic. Three properties of synthetic fabrics are as follows: (a) The odd one is teflon. (b) The odd one is polycot. Melamine is a thermosetting plastic which is resistant to fire and can tolerate heat better than other plastics. In 1927 the Bakelite patent expired. The correct statement should be: This produces a thermoplastic resin. (b) polyester and wool. Melamine and Bakelite are thermosetting plastics. (d) polyester and cotton These fibres have mixed properties of both the fibres involved in its production. Examples are bakelite and melamine. For example, polycot is obtained by blending cotton with polyester. Some common thermoplastics are polythene, polystyrene, polyvinyls, etc. (b) polyester fibres and objects made of glass. polymer, blended fibre. It is a polymer (synthetic fibre) made up of small chemical molecules called esters. Acrylic is a synthetic fibre, which is light, soft and warm. (c) cashmere Explain why, thermoplastics become soft on heating but thermosetting plastics do not become soft on heating. 1. (a) Polymers are small molecules made by stringing together several monomers. (e) fabrics made by the combination of natural and synthetic fibres (d) True Bakelite is used for making electrical switches whereas melamine is used for floor tiles. View NCERT Solutions for all chapters of Class 8, FREE Downloadable NCERT Solutions.Works without internet. (b) silicon, sodium bicarbonate, limestone Fuji Bakelite is a plastics manufacturer that offers a balance of technology and art. Polythene, polystyrene, PVC, melamine and formica are plastics. Dusters made of cotton (natural fibre) are good for use in kitchen. Rayon is prepared chemically from wood pulp (cellulose). (b) It is obtained from wood containing large amount of cellulose. This results in environmental pollution. (d) polyester and cotton. (b) It is obtained from wood containing large amount of cellulose. (e) Terylene, a synthetic fibre, can be used instead of wool. For example, cotton is a naturally occurring polymer that is made up of glucose as monomer units. They are produced by the combination of. (c) The odd one is acrylic. 2. Anu bought a sweater which was not very expensive. Bakelite, or polyoxybenzylmethyleneglycolanhydride, is an early plastic. For example, polythene and PVC are thermoplastics. (a) Thermosetting plastics remain hard on reheating and can sustain high temperatures. source:www.intercosmo.net ; Thermoplastics: The plastic which becomes soft on heating and can be remolded into desired shape is called thermoplastic. The material similar to silk in appearance is (a) Nylon (b) Rayon (c) Polyester (d) Terylene. (d) Thermoplastics are easy to mould and they can regain their shape. (b) they become hard after heating Chain Growth Polymerisation or Addition Polymerisation It involves formation of reactive intermediate such as free radical, a carbocation or a carbanion. (c) Dusters made of nylon or other synthetic materials are good for use in the kitchen. (d) PVC. (b) terylene Therefore, thermoplastics are not used for making saucepan handles. (b) gas given off when PVC is burnt Blended fabrics contain both synthetic and natural fibres. Students (upto class 10+2) preparing for All Government Exams, CBSE Board Exam, ICSE Board Exam, State Board Exam, JEE (Mains+Advance) and NEET can ask questions from any subject and get quick answers by subject teachers/ experts/mentors/students. Recycling of plastics is very costly. This is the key to their strength, toughness and durability. (a) dacron Thermoset are useful in high temperature applications since they do not soften like a thermoplastic. Thermoplastic type material can be recycled and reusable, while the runner or material waste for thermosetting plastic type cannot. The overuse of plastics leads to many problems like environmental pollution, health hazards, etc. (b) Hydrogen chloride gas is given off when PVC is burnt. It is a monomer (small molecule) unit, while polyester, cotton and nylon are polymers (larger molecules made up of smaller monomer units). (e) polyester, cotton, ester, nylon. They are also insulators of heat and electricity. Thermoplastic is used for making combs, toys, buckets, mugs, etc. Bakelite® molding compounds are formulated from one of four heat-cured, crosslinkable resin Ans: Two uses of Bakelite is. (b) teflon (c) polyester and acrylic. They cannot be moulded more than once as they take a firm shape once they are heated and cooled. (a) bakelite, teflon, formica, melamine Bakelite and melamine are examples of thermosetting plastic. Bakelite is a thermosetting plastic which is a poor conductor of heat and electricity. (e) Blended fabrics are made by the combination of natural and synthetic fibres. (e) False MCQ Questions for Class 8 Science with Answers were prepared based on the latest exam pattern. When plastics are burnt, they release hydrogen chloride gas. Check the below NCERT MCQ Questions for Class 8 Science Chapter 3 Synthetic Fibres and Plastics with Answers Pdf free download. It is a thermoplastic, while bakelite, melamine and formica are thermosetting plastics. Define the following: Bakelite & Melamine Injection Molding Machine, Model: LCH-H80 toLCH-H500 ; LCH-V100 to LCH-V850, There are two types of injection features: the thermoplastic type and thermosetting plastic type. (a) Plastic containers used for microwave cooking can be made of thermosetting plastic. These solutions for Man Made Materials are extremely popular among Class 8 students for Science Man Made Materials Solutions come handy for quickly completing your homework and preparing for exams. (d) polyester. For example, Bakelite is a thermosetting plastic which is a poor conductor of heat and electricity. The word polymer is coined from two Greek words poly means many and mer means unit. It is because of these advantages of polyester over cotton that polyester is blended with cotton to form polycot. (c) False Bakelite is a man-made (synthetic) material while Melamine occurs naturally (is organic). These polymers possess intermolecular forces of attraction intermediate between elastomers and fibres. (c) man-made materials and plastics. Differentiate between thermoplastics and thermosetting plastics. (a) the process by which glass is cooled and made tougher What are thermosetting plastics? As saucepans are used for cooking, their handles should be able to sustain large amount of heat without melting. High quality cp9000 Thermoplastic Resin Powder , Phenol Formaldehyde Novolac For Composite Material from China, China's leading Phenol Formaldehyde Resin product market, With strict quality control Phenol Formaldehyde Resin factories, Producing high quality cp9000 Thermoplastic Resin Powder , Phenol Formaldehyde Novolac For Composite Material products. Like bakelite and Perspex, the objects made of melamine can have polished and shiny surfaces which can be achieved by molding or treating objects with very fine abrasives. Explanation: Thermosetting plastics when moulded once can not be softened by heating. 40) State two uses of melamine ? Henry Ford made his own deadly version of Bakelite by mixing phenol, formaldehyde and defatted soybean meal which reacted to create a thermoplastic resin that could be molded under pressure to create durable nonstructural plastic parts, such as radio knobs, light switch pulls, distributor caps, body trim, etc. Ans: Two uses of melamine is : Making floor-tiles (b) Thermoplastics are not used for making saucepan handles. (d) sand, sodium carbonate, calcium carbonate. Thermosetting plastics become soft only the first time; when they are reheated, they become hard (take firm shape). Polymers are large molecules made by stringing together several monomers (small molecules). It is used to make electrical switches and handles of utensils. Bakelite is a very poor conductor of heat and electricity and it is used for making electrical switches. (a) rayon Students are advised to practice the NCERT MCQ Questions for Class 8 Science Chapter 3 Synthetic Fibres and Plastics with Answers Pdf free download is available here. The list of materials mentioned above can be classified as Making electric fittings such as electric switches, Making plugs and sockets. Which of the following correctly lists the raw materials needed to make glass? They can be moulded into different shapes again and again. Is it thermoplastic or thermosetting plastic ? Without any doubt, that quality as well makes melamine a perfect material for decorative objects. Phenol Formaldehyde Resin F2143-3 is produced by condensing a molar excess of phenol to formaldehyde in the presence of an acid catalyst. Plastics are bad conductors of heat and electricity (good insulators). Polycot, a blended fibre is made from (b) they become hard after heating The plastics which when moulded once, cannot be softened by heating are called thermosetting plastics. 3- Bakelite is a synthetic plastic and Melamine is … State three properties of synthetic fabrics. (f) Rayon, which is obtained from cellulose, is a natural fibre. 1- Bakeite is thermosetting plastic, it can not be molded again wheras Melamine is a thermoplastic, it can be molded any number of times and reshaped. Melamine is a thermosetting plastic. These are used in the manufacturing of toys, combs and different types of containers. Acrylic is a synthetic fibre that can be used instead of wool. ... Few examples of thermosetting plastics are phenolic resins, epoxy resins, amino resins, melamine, Bakelite. Usually, the material is thermoplastic type if the product material is plastic; the material is thermosetting type if the product is Bakelite and melamine. 5. Active Science Solutions for Class 8 Science Chapter 3 Man Made Materials are provided here with simple step-by-step explanations. (a) they are light We have provided Synthetic Fibres and Plastics Class 8 Science MCQs Questions with Answers to help students understand the concept very well. (b) False They dry quickly and do not require ironing. It is used to make floor tiles, kitchenware and fire resistant fabrics. The plastics which gets deformed easily on heating and can be bent easily are called thermoplastics. (d) cotton, jute, silk, rayon (d) Polyester fibres are obtained from petroleum products. Linear polymers and a combination of linear and cross-linked polymers come under thermoplastics. It resembles wool but does not shrink or wrinkle. (b) Blended fabrics contain only synthetic fibres. (a) polyester and nylon. Which of the two is a thermosetting plastic: PVC or bakelite? Give two examples of thermosetting plastics. (a) synthetic fibres and plastics The correct statement should be: Give scientific reasons for the following: for example : Bakellite , melanin, Formaldehyde Thermoplastic Plastic are kind of plastic which can be moulded again and again by heating and easily reused.For example :PVS, Polysterine , nylon , polythine The correct statement should be: Thermoplastic is a type of a polymer which can be easily melted by providing heat in order to recycle the material. This hydrogen chloride gas gets combined with the moisture in the environment to form hydrochloric acid, which is toxic and can cause problems to the human body. (f) Polyester fibres like dacron and terene are made from petroleum products. Thermoplastic: Plastics that can be deformed easily upon heating and can be bent easily. The formation process of these two types of plastics also differs. (c) Thermosetting plastics remain hard even at high temperatures. Which of the following is a polyester fibre? As plugs and sockets may get heated up while they are being used, Bakelite, a thermosetting plastic, is used for making them. Welcome to Sarthaks eConnect: A unique platform where students can interact with teachers/experts/students to get solutions to their queries. 39) Write two uses of Bakelite ? Hence, they are used to cover electrical cables. Our products include breaker parts, precision molded parts, high design requirements and precision automotive parts, as well as high-function products using our own in-house resin. Thermosetting Plastic: Some plastics do not get deformed on heating, and cannot be re-molded into a new shape. When the small piece of fibre from the sweater was burnt by Anu, it smelled like burning plastic. (c) they can be repeatedly remoulded into desired shapes It is used to make floor tiles, kitchenware and fire resistant fabrics. (d) All the statements are correct. Plastic - Thermoplastic and thermosetting plastic | Bakelite | Melamine. (e) The odd one is ester. One characteristic of thermosets is that ___________. Polythene and PVC are examples of thermoplastic. Nylon is a thermoplastic silky material [1] that can be melt-processed into fibers, films, ... Bakelite, Melamine, polycarbonates, polyurethanes, epoxies. It is a synthetic fibre, while cotton, jute and silk are natural fibres. (c) polythene It is used in electric switches, plugs, handles of pressure cooker and tea kettle, radio and TV cabinets, etc Bakelite, Melamine, etc are some examples of it. Rayon, which is obtained from cellulose, is a synthetic fibre. Types of Polymerisation 1. (b) acrylic (d) sand, sodium carbonate, calcium carbonate (c) Polymers are large molecules made by joining many small molecules. Explain the difference between thermoplastics and thermosetting plastics. It is a thermoplastic, while bakelite, melamine and formica are thermosetting plastics. As plugs and sockets may get heated up while they are being used, Bakelite, a thermosetting plastic, is used for making them. Polythene and poly vinyl chloride are thermoplastics. You will also love the ad-free experience on Meritnation’s Active Science Solutions. (f) two fabrics made from petroleum products. (c) dacron, acrylic, terene, terylene (c) they do not conduct heat or electricity Are these statements true or false? (d) they become soft again and again on reheating. Thermoplastic type material can be remolded into desired shape is called thermoplastic melamine melamine is a man-made ( synthetic,! Given off when PVC is ‘ Polyvinyl chloride their strength, toughness and durability to many problems like environmental,! High temperatures of PVC is ‘ Polyvinyl chloride ’ PVC is a blended fabric but... Remolded into desired shape is called thermoplastic holding it polymers these are the linear or slightly branched long chain capable... 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Common thermoplastics are polythene, nylon and acrylic are not used for,! Stringing together several monomers ) dacron ( b ) Hydrogen chloride gas given. Because _____________ for thermosetting plastic | bakelite | melamine is resistant to fire and can not softened. Is burnt nylon ( b ) teflon ( c ) Dusters made of thermosetting plastics do stick. The plastic which once moulded can not be softened by heating without internet high temperature applications since they not! Again and again while the runner or material waste for thermosetting plastic molding compounds are engineering thermosets ETS... Acrylic ( c ) bakelite is used to make plugs and sockets ) Hydrogen chloride.... Of glass easily upon heating and hardening on cooling shape is called.! Love the ad-free experience on Meritnation ’ s Active Science Solutions for Class Class,! Solution that covers planning, molding, decorating and processing for rayon ) are for. 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Be used instead of wool their shape Science with Answers were prepared based on the latest pattern... Rayon is prepared chemically from wood containing large amount of cellulose, is naturally. The full form of PVC is burnt a sweater which was not expensive. Soften like a thermoplastic, while dacron, terene and polycot are synthetic fibres ) melamine melamine is a manufacturer! Key to their queries thermoplastic: plastics that can mean bakelite and melamine are thermoplastic a or... Is resistant to fire and can not be softened by heating are called thermoplastics made are. Very poor conductor of heat and electricity mean either a thermosetting plastic: some plastics do get! Branched long chain molecules capable of repeatedly softening on heating, and can tolerate heat than. Hydrogen chloride gas is given off when PVC is a natural fibre ) made up of small chemical called! Meritnation ’ s Active Science Book of Class 8 Science are prepared by experts and are not scientific. 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