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Right option is (b) False

Best explanation: A barrel is an instrument that is PLACED near the nozzle, and it plays no role in the opening and closing of the mold. There is a CLAMPING UNIT employed for HOLDING the two halves together and for the opening and closing of the mold.

Correct choice is (b) False

The best I can EXPLAIN: Injection molding is CONSIDERED to be one of the most widely used methods. In this method, there are dies that EJECT the solidified COMPONENT, before which it is KEPT under constant pressure.

The correct answer is (a) 300°C

For EXPLANATION: The MAXIMUM allowable TEMPERATURE that can be given to the system is 300°C, in this PARTICULAR method of MOLDING.

The CORRECT answer is (C) Volume of material

Explanation: Among the FOLLOWING, the INNER pressure of the material, the outer pressure of the material as well as the mold and the temperature of the material and mold are important FACTORS to be considered. The volume of material is not counted among important factors.

Correct option is (d) 150°C

The EXPLANATION is: In the molding process of POLYMERS in thermoplastics, INJECTION molding process is the most common of the methods. The minimum allowable temperature that can be GIVEN to the system is 150°C.

Correct option is (B) Tubes

Easiest explanation: Injection molding is one of the most widely used method of molding AMONG molding with POLYMERS. There are various applications of this method such as nuts, bolts, cups, car handles, ELECTRICAL fitting parts, but not tubes and rods.

Correct CHOICE is (b) Hopper

Explanation: In a ram or plunger type injection molding SYSTEM, the granular molding MATERIAL has to be first loaded into a hopper, after which, with the help of a feeding device it gets metered out INSIDE a cylinder.

Correct choice is (a) Hydraulic ENERGY

The best explanation: There is a clamping unit employed for holding the two HALVES together and for the opening and closing of the mold. A moving piston is PROVIDED which OPERATES the power press. This piston works on hydraulic energy.

Correct choice is (c) WATER

To EXPLAIN: When it comes to MOLDING of POLYMERS in thermoplastics, injection molding process is the most common of the methods. In this method, whenever the die has to be COOLED, there is water used to cool it.

The correct choice is (a) True

For explanation I would say: MECHANICAL properties relate to movement or breakage of the polymer DUE to some mechanical variation such as application of load. Mechanical properties are mainly dependent on the temperature, force or load APPLIED, and the DURATION of time the force is applied. It can also be affected by ultra-violet radiation when USED outside.

Correct OPTION is (b) False

Explanation: For the manufacturing of windshield for airplane, poly-acrylics plastics are used which basically belongs to the group of thermoplastics. Poly-acrylics are transparent, HIGH tough in nature and can be easily SHAPED in any FORM. DUE to such properties of this material, it is widely used for making of windshields for airplane.

Right answer is (a) True

To elaborate: Phenolic plastics or polymers are BELONGS to THERMOSETTING plastics. These are the special type of resins which can be used in potting compounds, casting resins, and LAMINATING resins. They can also be used in making of electrical EQUIPMENT. Phenolic plastics are very POPULAR binders for holding plies of wood in manufacturing of plywood.

The CORRECT choice is (a) True

The explanation is: Epoxies can be used in various ways. In adding with GLASS fibers, it is capable of making composites that are of HIGH STRENGTH and HEAT resistant. These composites are basically used for making motor casings in missiles, aircraft parts, fixtures etc. Epoxies are also found in industrial equipment and in protective coatings of appliances.

The correct option is (b) False

For explanation: Polyurethane plastics come in the category of thermosetting plastics. In this TYPE of plastics, elasticity is generally very high. Due to this property of high elasticity, it can be used in decorative and PROTECTIVE COATINGS. The high elasticity also makes these polyurethane polymers highly resistant to any CHEMICAL ATTACK.

Correct OPTION is (a) True

To elaborate: Polyurethane PLASTICS are belonged to the thermosetting plastics or POLYMERS. Polyurethane is the only polymer that can be formed in both rigid and flexible foams. The flexible polyurethane FOAM is generally used in the manufacturing of mattresses, carpets and FURNITURE. And the rigid polyurethane foam is used in making of chairs and mirror frames.

Right answer is (b) False

The explanation: Polyethylene, polypropylene and polyvinyl chloride (PVC) are basically EXAMPLES of thermoplastics material. And thermosetting material’s example includes polyurethanes, polyesters, epoxy resins and PHENOL resins which are USED for manufacturing of aircraft parts, TIRES and AUTO parts.

Right answer is (a) True

To explain I WOULD say: Thermosetting polymers basically involve CROSS-linked molecular structure and thus it is ideal for MAKING PRODUCTS which demand rigidity and strength. Due to cross linking in thermosetting polymers, these are MADE hard, tough, and cannot be re-moulded as thermoplastic polymers.

The correct OPTION is (c) Cross-linked POLYMERS

Best explanation: Cross-linked polymers are described by ADJACENT linear CHAINS that are brought one to ANOTHER at several locations by covalent bonds. Cross linking is completed by a non-reversible chemical reaction. Often, cross-linking is finished by additive atoms which are covalently bonded to the chains in the thermosetting polymers.

The correct answer is (a) True

The BEST I can EXPLAIN: It is counted among one of the advantages of transfer molding over compression molding that the speed of production is quite HIGHER. Not just that, but the MAINTENANCE in transfer molding too is lower than compression molding.

The CORRECT option is (a) 20 MPa

Easiest EXPLANATION: The maximum PRESSURE that is required for the COMPLETE operation of transfer molding is 20 MPa.

Right choice is (b) 0.5 minutes

Explanation: The minimum curing TIME that is required for the COMPLETE OPERATION of COMPRESSION molding is 0.5 minutes.

Right choice is (C) 100 MPa

Best EXPLANATION: Processing of thermosetting plastics is classified as, compression MOLDING and transfer molding. The MAXIMUM pressure that is REQUIRED for the complete operation of transfer molding is 100 MPa.

The correct answer is (d) 5 MINUTES

To elaborate: The maximum curing time that is REQUIRED for the COMPLETE operation of compression molding is 5 minutes.

Correct option is (b) Curing temperature

To explain I would say: When there has to be molding done for thermosetting materials, mainly compression molding is PREFERRED. While doing this, curing has to be done. The TIME NEEDED for curing depends on the MATERIAL used, geometry and THICKNESS of the material.

The CORRECT OPTION is (c) 250°C

For explanation: Processing of thermosetting plastics is CLASSIFIED as, compression molding and transfer molding. The MAXIMUM temperature that is required for the complete operation of compression molding is 250°C.

The CORRECT CHOICE is (B) 125°C

The EXPLANATION: NONE.

The CORRECT option is (d) 50 MPa

For explanation I would SAY: The MAXIMUM pressure that is required for the complete operation of compression molding is 50 MPa.

Right answer is (a) 0.5 MPA

To explain: PROCESSING of THERMOSETTING plastics is CLASSIFIED as, COMPRESSION molding and transfer molding. The minimum pressure that is required for the complete operation of compression molding is 0.5 MPa.