(a) bakelite, teflon, formica, melamine Bakelite is a thermosetting plastic which is a poor conductor of heat and electricity. Recycling of Plastic. The decorative melamine board has a structure obtained by laminating a surface layer and a core layer. State three properties of synthetic fabrics. (b) they become hard after heating Blended fabrics contain both synthetic and natural fibres. 40) State two uses of melamine ? Choose the thermoplastics and thermosetting plastics from the following: Melamine, Polythene, Bakelite, Polyvinyl chloride. Phenol Formaldehyde Resin Powder Heat Resistance for Brake Pads Product description . (c) Bakelite is used to make plugs and sockets. Acrylic is a synthetic fibre that can be used instead of wool. Melamine and Bakelite are thermosetting plastics. (a) dacron Phenol Formaldehyde Resin F2143-3 is produced by condensing a molar excess of phenol to formaldehyde in the presence of an acid catalyst. (c) cashmere (a) sand, sodium bicarbonate, limestone (d) cotton, jute, silk, rayon Some examples are bakelite, melamine, formica, etc. It is usually elastic and soft. Polythene and poly vinyl chloride are thermoplastics. Thus, the sweater was not pure wool, but it was made of synthetic acrylic fibre. (b) polyester and wool. Thermoplastic is used for making combs, toys, buckets, mugs, etc. The correct statement should be: The correct statement should be: They are produced by the combination of synthetic fibres and natural fibres. We can sort the given fabrics into natural, synthetic and blended fibres as shown in the table below: Find the odd one out in the following. Bakelite is a man-made (synthetic) material while Melamine occurs naturally (is organic). (d) Polyester fibres are obtained from petroleum products. It is a blended fabric, but rayon, nylon and acrylic are not. The word polymer is coined from two Greek words poly means many and mer means unit. They are also insulators of heat and electricity. Rayon looks like silk. 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. Once processed and cured, they are infusible and cannot be re-melted or dissolved. (a) polyester and nylon. It is a thermoplastic, while bakelite, melamine and formica are thermosetting plastics. Thermosetting plastics become soft only the first time; when they are reheated, they become hard (take firm shape). Hence, they are used to cover electrical cables. (b) False (b) Blended fabrics contain only synthetic fibres. All Active Science Solutions for class Class 8 Science are prepared by experts and are 100% accurate. ... Few examples of thermosetting plastics are phenolic resins, epoxy resins, amino resins, melamine, Bakelite. (e) polyester, cotton, ester, nylon. Rayon, which is obtained from cellulose, is a synthetic fibre. (f) Rayon, which is obtained from cellulose, is a natural fibre. Thermoplastic: Plastics that can be deformed easily upon heating and can be bent easily. Which of the two is a thermosetting plastic: PVC or bakelite? (c) Dusters made of nylon or other synthetic materials are good for use in the kitchen. They are produced by the combination of. 1 Answer +1 vote . (a) the process by which glass is cooled and made tougher Name the following: 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. As plugs and sockets may get heated up while they are being used, Bakelite, a thermosetting plastic, is used for making them. They cannot be moulded more than once as they take a firm shape once they are heated and cooled. Fuji Bakelite is a plastics manufacturer that offers a balance of technology and art. Blended fibres are fibres that are obtained by blending natural fibres with synthetic fibres. Melamine is a thermosetting plastic which is resistant to fire and can tolerate heat better than other plastics. This results in environmental pollution. (d) All the statements are correct. Plastics are not biodegradable and take thousands of years to degenerate. (b) gas given off when PVC is burnt Bakelite is a thermosetting plastic, it cannot be molded again whereas Melamine, being a thermoplastic, can be molded any number of times adn reshaped. (a) Annealing is the process by which glass is cooled and made tougher. It resembles wool but does not shrink or wrinkle. They dry quickly and do not require ironing. Differentiate between thermoplastics and thermosetting plastics. 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. It is a thermoplastic, while bakelite, melamine and formica are thermosetting plastics. What are thermosetting plastics? Anu bought a sweater which was not very expensive. Bakelite and melamine are examples of thermosetting plastic. As saucepans are used for cooking, their handles should be able to sustain large amount of heat without melting. Thermoplastic type material can be recycled and reusable, while the runner or material waste for thermosetting plastic type cannot. These polymers possess intermolecular forces of attraction intermediate between elastomers and fibres. Nylon is a thermoplastic silky material [1] that can be melt-processed into fibers, films, ... Bakelite, Melamine, polycarbonates, polyurethanes, epoxies. Three properties of synthetic fabrics are as follows: (a) The odd one is teflon. They absorb water and do not catch fire easily. The list of materials mentioned above can be classified as 2. Without any doubt, that quality as well makes melamine a perfect material for decorative objects. For example, cotton is a naturally occurring polymer that is made up of glucose as monomer units. They are also insulators of heat and electricity. 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. Therefore, thermoplastics are not used for making saucepan handles. (b) It is obtained from wood containing large amount of cellulose. It is used to make floor tiles, kitchenware and fire resistant fabrics. (a) rayon (a) synthetic fibres and plastics. You will also love the ad-free experience on Meritnation’s Active Science Solutions. It is a polymer (synthetic fibre) made up of small chemical molecules called esters. (b) The odd one is polycot. (c) dacron, acrylic, terene, terylene The overuse of plastics leads to many problems like environmental pollution, health hazards, etc. (b) acrylic Thermoset are useful in high temperature applications since they do not soften like a thermoplastic. Polyesters are wrinkle-free and do not require ironing. (f) two fabrics made from petroleum products. Give two examples of thermosetting plastics. Rewrite the false ones correctly. Some common thermoplastics are polythene, polystyrene, polyvinyls, etc. These are used in the manufacturing of toys, combs and different types of containers. 39) Write two uses of Bakelite ? One characteristic of thermosets is that ___________. 3. The key difference between thermoplastic and thermoset is that thermoplastic can be melted into any shape and re-used whereas thermosets have a permanent shape and cannot be recycled into new forms of plastic.. Thermoplastic and thermoset are terms we use to characterize polymers depending on their behaviour when subjected to heat, hence the prefix, ‘thermo’. (c) polyester and acrylic. When plastics are burnt, they release hydrogen chloride gas. Making electric fittings such as electric switches, Making plugs and sockets. Give scientific reasons for the following: (a) Annealing is the process by which glass is cooled and made tougher. (d) they can coloured by adding pigments. (b) polyester fibres and objects made of glass. Ans: The full form of PVC is ‘ Polyvinyl chloride’ PVC is a thermoplastic. 5. View NCERT Solutions for all chapters of Class 8, FREE Downloadable NCERT Solutions.Works without internet. Is it thermoplastic or thermosetting plastic ? What is the sweater most likely made of? Which of the following correctly lists the raw materials needed to make glass? Polymers are large molecules formed by the linkage of smaller molecules called monomers. source:www.intercosmo.net ; Thermoplastics: The plastic which becomes soft on heating and can be remolded into desired shape is called thermoplastic. (c) Thermosetting plastics remain hard even at high temperatures. 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 It is not a polyester synthetic fibre, while dacron, terene and terylene are polyester synthetic fibres that are manufactured from petroleum products. (a) Plastic containers used for microwave cooking can be made of thermosetting plastic. (c) Polymers are large molecules made by joining many small molecules. Kerala Plus Two Chemistry Notes Chapter 15 Polymers. All questions and answers from the Active Science Book of Class 8 Science Chapter 3 are provided here for you for free. (a) Thermosetting plastics remain hard on reheating and can sustain high temperatures. They can be moulded into different shapes again and again. Plastic is a very generalized term for polymers that can mean either a thermosetting or a thermoplastic Plastic. (b) terylene It is a synthetic fibre, while cotton, jute and silk are natural fibres. Sand (silicon dioxide (SiO2), sodium carbonate (Na2CO3) and calcium carbonate (CaCO3) are the three raw materials needed to make glass. (c) they can be repeatedly remoulded into desired shapes 2- Bakelite is a synthetic (man-made) material while Melamine is an organic or natural material. ​Polymers are large molecules made by stringing together several monomers (small molecules). Explanation: Thermosetting plastics when moulded once can not be softened by heating. (a) they become soft on cooling What problems can be caused by the overuse of plastics? Are these statements true or false? (a) It resembles wool in appearance. Bakelite is a very poor conductor of heat and electricity and it is used for making electrical switches. In 1927 the Bakelite patent expired. The plastics which gets deformed easily on heating and can be bent easily are called thermoplastics. A thermoset material as the name implies can be heated only once because an irreversible reaction occurs so that the material remains solid in what ever form it is in when the reaction takes place. Sort out these fabrics into different groups: rayon, nylon, jute, acrylic, terylene, wool, silk, polyester, terry cotton, cotton. Nylon, rayon, acrylic, terene and polycot are synthetic fibres. Thermoplastic is a type of a polymer which can be easily melted by providing heat in order to recycle the material. Ans: Two uses of Bakelite is. Plastics are used to cover electrical cables because _____________. (c) It is a naturally occurring fibre obtained from wood. (b) they become hard after heating Example: Bakelite, melamine, etc. Define the following: Polycot, a blended fibre is made from (b) The odd one is polycot. Usually, the material is thermoplastic type if the product material is plastic; the material is thermosetting type if the product is Bakelite and melamine. The correct statement should be: The plastics which when moulded once, cannot be softened by heating are called thermosetting plastics. (e) fabrics made by the combination of natural and synthetic fibres Bakelite, or polyoxybenzylmethyleneglycolanhydride, is an early plastic. Chain Growth Polymerisation or Addition Polymerisation It involves formation of reactive intermediate such as free radical, a carbocation or a carbanion. 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