Plastics Engineering Interview Questions and Answers
Question - 21 : - Why Doesn’t The Council Recycle More Materials At The Kerbside?
Answer - 21 : -
As an authority, Powys is committed to providing the most efficient and cost-effective service to residents. As part of this, we need to consider which materials offer the best value to collect. Our service allows for the recycling of up to 70% of the waste typically produced by households. While some additional materials, like plastic film, could be recycled, this would cost a lot for a limited benefit and would be uneconomical to do so.
When a product such as crisp packets is made, the manufacturers often use lots of different materials. This makes it very difficult to find processors that can recycle these products efficiently and cost effectively.
The materials collected at the kerbside are limited by the number of compartments on the recycling vehicles. The council collects plastics and cans, paper and card, glass and food waste recycling which are the most frequently produced items by households. A range of materials such as textiles, grass cuttings and large cardboard items can be recycled at community recycling sites. Larger items such as washing machines and furniture, as well as low energy or florescent light bulbs, car tyres can be taken to a household waste recycling centre.
Question - 22 : - Explain The Term ‘thermoset Polymer’, With Reference To Molecular Structure?
Answer - 22 : -
Once 'set' these plastics cannot be reheated to soften, shape and mould. The molecules of these plastics are cross linked in three dimensions and this is why they cannot be reshaped or recycled. The bond between the molecules is very strong.
Question - 23 : - Describe The Properties Of The Polymer You Have Named Above That Make It Suitable For Electrical Fittings?
Answer - 23 : -
Urea Formaldehyde has physical properties of high hardness and high toughness, making it suitable for strong, knock-resistant electrical fittings. It is also scratch resistant and a very good electrical insulator, making electrical fittings manufactured from this polymer safe to use.
Question - 24 : - Explain The Term ‘thermoplastic’, With Reference To Molecular Structure?
Answer - 24 : -
These plastics can be re-heated and therefore shaped in various ways due being long chain monomers that are not inter- connected. They become mouldable after reheating as they do not undergo significant chemical change. Reheating and shaping can be repeated. The bond between the molecules is weak and become weaker when reheated, allowing reshaping. These types of plastics can be recycled.
Question - 25 : - Thermoplastics Are Very Useful In The Manufacture Of Mobile Phone Casings. Name A Thermoplastic Used For This Purpose?
Answer - 25 : - Polycarbonate.
Question - 26 : - Describe The Properties Of The Polymer You Have Named Above That Make It Suitable For Mobile Phone Casings?
Answer - 26 : -
Polycarbonate is a thermoplastic which means it can be shaped and formed through a number of manufacturing processes. It machines well and can be solvent bonded and welded. It is tough and resistant to damage which is an ideal property for a mobile phone. If dropped, a mobile phone with a polycarbonate casing is likely to survive undamaged. It is an insulator, often used to insulate electrical circuits. It is supplied in a range of colours.
Question - 27 : - Are Plastics Eco-friendly?
Answer - 27 : -
In General all man-made products, during manufacture, processing and disposal, have an impact on the environment. The issue therefore is, which of these products under consideration, will impose the least burden on the environment, and contribute to what is termed - 'sustainable development'.
Question - 28 : - How Do We Judge Whether Plastics Are Eco-friendly In Relation To Other Materials?
Answer - 28 : -
Plastindia Foundation's Enviroplast Committee, developed a model or criteria, which may be used forqualifying materials as eco-friendly. The material or product in question should:
- Improve the qualify of life, particularly of the economically weaker sections of society.
- Reduce signaficantly the pollution load on the environment - and water and air in relation to materials that are replaced or substituted.
- Use the non-renewable energy resources more efficiently.
- Contribute to the presevation of land, water resources and forests.
- Lend itself to recycling and/or recovery of a significant part of the inherent energy.
Normally the tendency is to judge a product or item in terms of its waste disposal problem. This islikesaying that an ice-berge is as big as it appears above the surface.
Every process connected with a product, right from the time that basic raw materials are extracted from theearth to the time a product is produced, transported, used and disposed, has some impact on the environment.
A comparative study of products or applications based on measurements of energy-input and the pollution discharged to land, water and air, at every stage, is called a Life Cycle Analysis (L.C.A.) - or more simply 'the cradle to grave' approach.
Question - 29 : - Are Plastics Responsible For Utilising A Major Share Of The World's Oil Or Hydrocarbon Resources?
Answer - 29 : -
NO. It is important to recognise that plastics use less than 4% of the world's hydrocarbon resources. Approximately 90% is consumed for transportation, power generation and heating.
In general plastic products require less energy than products made from conventional materials, at comparableuse and performance levels.
Question - 30 : - Do Plasticss Make-up A Large Part Of The Municipal Solid Waste?
Answer - 30 : -
NO. A study conducted by the National Environmental Engineering Reasearch Institute, Nagpur for the BMC, putsthe figure at 0.75%.
Even in Europe and U.S.A., with per capita consumption of plastics at over 50 kgs per annum (India is 2.7 kgsper annum), plastic waste makes up 8% of the total muncipal solid waste. The rest is made up of organic materials (33%), paper & board (30%), glass and metals (16%) and others (13%).
Plastics make a significant contribution by reducing the weight and volume of materials that are typically thrownaway. Unfortunately in India, waste is littered, instead of being disposed to facilitate collection and recycling.