Polymer Processing Final Exam

The ____________ unit is responsible for both heating and injecting the material into the mold.

_________________ consists of two main steps: heating and forming. eating is usually accomplished by radiant electric heaters, located on one or both sides of the starting plastic sheet at a distance of roughly 125 mm (5 in.). Duration of the heating cycle needed to sufficiently soften the sheet depends on the polymer, its thickness and color.

An extruder with an L/D ratio of 24:1 or greater provides adequate residence time to produce a homogeneous mixture.

The temperature of the typical extruder melted polymer is usually between ______________, and it is also under high pressure (2000 to 4000 psi).

In the cast film extrusion process, the molten polymer travels through a _________ die system to adopt its final flat film shape.

Screw length to diameter (L/D) ratios commonly lies in the range of _________________.

The objective of the _____________ system is to prevent downstream passage of melt impurities and/or gels that are formed during the extrusion process.

__________________ is a method of producing plastic film and sheet by squeezing the plastic through the gap (or ‘nip’) between two counter-rotating cylinders.

This process involves positive pressure to force the heated plastic into the mold cavity.

The most widely used plastic materials in thermoforming are the ____________ types.

This process of extrusion and solidification of innumerable filaments is called _____________ of polymers.

Which of the following is NOT one of the typically four types of spinning for polymers?

_____________ spinning involves the extrusion of two different types of the same polymer through the spinneret.

Molecules in a thermoplastic are held together by relatively ___________ intermolecular forces so that the material softens when exposed to heat and then returns to its original condition when cooled.

Elastomers are ____________ polymers

Which of the following is an example of an elastomer?

The following factors must be considered when using a compression molding method EXCEPT

Which of the following polymers are used to manufacture plastic water bottles?

____________________ is used to facilitate the adherence of inks or coatings onto the film surface it is necessary to apply a surface treatment by increasing the surface energy of the film

Polymeric coatings are comprised of which components?