1. Which of the following is not used for conversion of extruded plastic into sheets?
a) Cast Film Extrusion
b) Slit Die Extrusion
c) Blown Film Extrusion
d) Micro Extrusion
Discussion
Explanation: Micro Extrusion is not used for conversion of extruded plastic into sheets. Micro extrusion is the process to create comparatively smaller sized objects. Whereas, Cast Film Extrusion, Slit Die Extrusion and Blown Film Extrusion are used for conversion of extruded plastic into sheets.
2. Tubular Extrusion is also known as _______
a) Flat Film Extrusion
b) Blown Film Extrusion
c) Slit Die Extrusion
d) Cast Film Extrusion
Discussion
Explanation: Tubular Extrusion is also known as Blown Film Extrusion. Flat Film extrusion is also known as Cast Film and Slit Die Extrusion. Like Flat Film Extrusion, Tubular extrusion is also used to convert extruded plastic into sheets. It is done by blowing air through the center of tubular die, due to which the thin tube from extruder is inflated into a thin bubble and cooled, after which it is flattened and wound up.
3. Compression ratios for single screw extrusion should lie between ____ and ____
a) 2:1, 3:1
b) 1:2, 4:1
c) 2:1, 4:1
d) 1:2, 1:3
Discussion
Explanation: Compression ratios for single screw extrusion should lie between 2:1 and 4:1. Compression ratio is an important parameter for any extrusion process. Compression ratio is the ratio of the volume of one flight of the screw at the in-fees end to the volume of one flight at the die end.
4.The term BUR in extrusion and calendering of thermoplastics refers to _______
a) Blow Up Ratio
b) Bauxime Up Ratio
c) Bottom Upper Ratio
d) Bottom Up Ratio
Discussion
Explanation: The term BUR in extrusion and calendering of thermoplastics refers to Blow Up Ratio. It is the ratio of bubble diameter to die diameter. BUR for most blown films in packaging generally lies between 2:1 and 4:1.
5. Flexibility of plastic packaging films increases with increasing density.
a) True
b) False
Discussion
Explanation: The statement is false. Flexibility of packaging films increases with decreasing density. As the density increases, the forces amongst the monomers increases and the rigidity increases. Hence, flexibility decreases.
6. ________ is a process which combines layers of two or more plastics together at the point of extrusion.
a) Lamination
b) Plating
c) Co-extrusion
d) Calendering
Discussion
Explanation: Co-extrusion is a process which combines layers of two or more plastics together at the point of extrusion. Lamination is the process of packaging via combination of two or more materials by a solvent, adhesive or heat. Calendering is a complementary process to film and sheet extrusion, which involves the formation of continuous sheets of controlled thickness by passing plastic materials through rollers. Plating is the process of coating any surface (especially metal) by other metal, mostly by electrochemical cell.
7. Co-extrusion uses adhesives for binding between two layers.
a) True
b) False
Discussion
Explanation: The statement is false. Co-extrusion doesn’t use adhesives for binding between two layers. Co-extrusion uses solely heat for binding different layers of plastics. Lamination used adhesives for binding between two layers. Hence, co-extruded films are generally thicker than laminated films.
8. A single laminate layer is thicker than _____
a) 15 μm
b) 6 μm
c) 1 μm
d) 10 μm
Discussion
Explanation: A single laminate layer is thicker than 6µm. A laminate is made up of two or more layers which can be plastic or non-plastic. But at least one layer must be a plastic. All layers to make a laminate must be thicker than 6 μm. However, there is no upper limit for this.
9. Coating is the bonding of two or more layers.
a) False
b) True
Discussion
Explanation: The above statement is false. Coating is the process of applying one or more layers of a fluid or melt to the surface of a material, while laminating is the bonding of two or more webs/layers.
10. Materials other than a thermoplastic can be used in a laminate.
a) True
b) False
Discussion
Explanation: The given statement is true. Materials other than a thermoplastic can be used in a laminate. A laminate is defined as any combination of distinctly different plastic film materials or plastic plus non plastic materials (typically paper and aluminium foil).