POLYMER PROCESSING OPERATIONS – II (2008 Pattern) (Sem. – I)
Time :3 Hours] [Max. Marks :100
Instructions to the candidates:
1) Answer 3 questions from Section -1 and 3 questions from Section – II.
2) Answers to the two sections should be written in separate books.
3) Neat diagrams must be drawn wherever necessary.
4) Figures to the right indicate full marks.
5) Your answers will be valued as a whole.
6) Use of logarithmic tables, slide rule, Mollier charts, electronic pocket calculator and steam tables is allowed.
7) Assume suitable data, if necessary.
SECTION – I
QI) a) What is parison programming? How is it done? Discuss the process parameters which control the weight of the bottle. 
b) Explain what you understand by die shaping in blow molding. 
c) Compare single and two stage injection stretch blow molding of PET. 
Q2) a) Discuss the design features and requirements of extrusion blow moulding die head assembly. Also draw a neat sketch of the accumulator type of die head assembly. 
b) Write short notes on 
i) Parison sag in extrusion blow moulding
iii) Shark skin effect.
c) Discuss the various faults and remedies for the same in blow moulding of HDPE and PVC. 
Q3) a) Discuss the different types of heating modes for thin sheet and thick sheet in thermoforming. 
b) Explain the process of drape forming and pressure forming with a neat sketch. 
c) What are the advantages of thermoforming over injection molding? State the pre-stretch variables in thermoforming process. 
Q4) a) Explain the causes of wrinkling and whitening of sheets during thermoforming. 
b) Write short notes on (any two) : 
i) Diaphragm forming.
ii) Draw ratio and secondary draws.
iii) Twin sheet roll fed thermoforming.
c) Explain the significance of Biot number in case of thermoforming of thin and thick sheets. 
Q5) a) Draw a calendaring plant layout for making PVC sheet and explain all major stages involved in the plant. 
b) Discuss the different heating systems used in calendaring rolls. Discuss their merits and demerits. 
c) Discuss the various faults which occur in calendaring. 
Q6) a) With neat sketches explain the different types of calendar arrangements and discuss their merits and demerits. 
b) Write a short note on hydraulic pull backs used in calendaring. 
c) Draw a neat sketch 8 explain the embossing and laminating line 
SECTION – II
Discuss in short ‘rotational moulding of liquid polymers. 
Explain the different ways of bubble removal during rotational molding.
Explain how internal air temperature can be used as a tool of process control in rotational molding. 
Discuss the criteria for selecting a polymer material for rotational moulding. 
What are the advantages and limitations of rotational molding? 
Explain the independent arm rotational moulding machine with its advantages. 
Discuss the steps involved in powder metal injection moulding process.
List the various types of injection foam moulding processes and explain any one of them. Summarize the pros and cons of all the injection foan molding processes. 
Explain the different steps involved in water injection technique. State its advantages and disadvantages. 
Giving a suitable example, explain the structure development during injection moulding for a slow crystallising polymer. 
Discuss two – component micro injection molding w.r.t process details, mold and machine technology. 
Discuss the advantages and disadvantages of Gas assisted injection molding. Compare Water injection molding and Gas assisted injection molding. 
QII) a) Explain the process of vacuum metallizing adopted for metal deposition on plastic moulding. 
b) Write a short note on the following w.r.t waste management. 
c) Give the characteristics of laser machining of plastics. Explain the various applications of laser machining. 
Q12) a) Write short notes on (any two): 
i) Hot stamping
ii) In-mould decoration
iii) Gravure printing
b) How does the machining of metals differ from that of plastics? 
c) State the four ‘R’s of plastic waste management. Suggest the various methods to separate plastic solid waste.