Question 1. How Are Plastics Made?
Most commercial plastics encountered by consumers consist of building blocks of carbon. Those building blocks are typically derived from petroleum or natural gas, but can be derived from coal or biological sources. The building blocks of small molecules are called monomers. The monomers used are many and can be combined in various combinations to achieve special properties and characteristics.
The nature of the polymer science is such that the monomers must be very pure to make useful plastics. Plastics can be made at very high pressures using gases, in solvents or liquid emulsions, or as melted materials. Each plastic has preferred manufacturing techniques based on its specific chemistry. All successful chemical syntheses are characterized by purification of raw materials, reuse of surplus material, efficient conversion of materials to useful plastic, efficient use of energy, and minimized releases of byproducts to the environment.
Question 2. Why Are Plastics Used In Packaging?
Packaging serves many purposes. The public may think the package lasts only a few minutes during the use of the product, but the real demands are much more extensive. Packaging must deliver the product through a potentially long distribution chain to the consumer such that the product meets all expectations regardless of the history encountered. The package must allow the product to be attractive and must deliver aesthetic appeal and information.
The package must protect the product at low cost and ease of use with minimal environmental impact. And the package must meet the various regulatory requirements set by various governments. With the proper selection of plastic and packaging type, the quality of the product good, ranging from sensitive electronics to fresh foods, can be maintained during shipping, handling and merchandising. Plastics are a versatile family of materials that are suitable for a wide range of packaging applications.
In many cases, plastics offer the best protection while using minimal resources and creating less waste than alternative materials. A study in Germany showed that 400 percent more material by weight would be needed to make packaging if there were no plastics, and the volume of packaging would more than double1. Another European study showed that if plastic packaging did not exist, the annual extra burden required to replace the packaging function would consume an additional 14.2 millions tons of oil (equal to a line of super tanker ships over 14 miles long) and produce an additional 47.3 million tons of CO2 (equal to the annual output of over 12 million automobiles)2. While all packaging continues to be optimized, the basic message of the efficiency of plastic packaging to deliver a product as expected and at low cost is still true.
Question 3. Why Do We Need Different Kinds Of Plastics?
Copper, silver and aluminum are all metals, yet each has unique properties. We do not make a car out of silver or a beer can out of copper because the properties of these metals are not the best choice for final product. Likewise, while plastics are all related, each resin has attributes that make it best suited to a particular application. Plastics make this possible because as a material family they are so versatile.
For instance, six resins account for most of the plastics used in packaging:
- PET (polyethylene terephthalate) is a clear, tough polymer with exceptional gas and moisture barrier properties. PET’s ability to contain carbon dioxide (carbonation) makes it ideal for use in carbonated soft drink bottles.
- HDPE (high density polyethylene) is used in milk, juice and water containers in order to take advantage of its excellent protective water retention properties. Its chemical resistance properties also make it well suited for items such as containers for household chemicals and detergents. And HDPE is used for the secondary packaging, such as reusable pallets, that helps deliver products safely and efficiently in the product distribution system.
- Vinyl (polyvinyl chloride, or PVC) provides excellent clarity, puncture resistance, and cling. As a film, vinyl can breathe just the right amount, making it ideal for packaging fresh meats that require oxygen to ensure a bright red surface while maintaining an acceptable shelf life.
- LDPE (low density polyethylene) offers clarity and flexibility. It is used to make bottles that require extra flexibility. To take advantage of its strength and toughness in film form, it is used to produce grocery bags and garbage bags, shrink and stretch film, and coating for milk cartons.
- PP (polypropylene) has high tensile strength, making it ideal for use in caps and lids that have to hold tightly on to threaded openings. Because of its high melting point, polypropylene can be hot-filled with products designed to cool in bottles, including ketchup and syrup. It is also used for products that need to be incubated, such as yogurt.
- PS (polystyrene), in its crystalline form, is a colorless plastic that can be clear and hard. It can also be foamed to provide exceptional insulation properties. Foamed or expanded polystyrene (EPS) is used for products such as meat trays, egg cartons and coffee cups. EPS is also used for secondary packaging to protect appliances, electronics and other sensitive products during transport.
Question 4. What About Cfcs Used In Plastics?
Chlorofluorocarbons (CFC’s) were used in the past to make foamed plastic. In response to concerns about the ozone layer, polystyrene manufacturers voluntarily phased out the use of CFC’s in the late 1980s.
Question 5. Are Toxic Compounds Used To Make Plastics And If So, Would Not The Plastics Be Toxic?
Some of the raw materials used to make plastics are rather non-reactive at room temperature and others are highly reactive. For example, one reactive compound, ethylene, is used to make polyethylene. It can also be used to make waxes, such as paraffin wax used for candles and food additives. While not particularly toxic, gaseous ethylene is an asphyxiant, chemically active, and highly flammable. When converted to a plastic, those characteristics are changed. The plastics made from transformed raw materials do not have the same properties as the raw materials. EPA has concluded “there is an exceedingly low probability that potential exposure to high molecular weight water-insoluble polymers, as a class, will result in unreasonable risk or injury to human health or the environment”.3Plastics molecules are very large and do not have the same biological properties as the raw materials used to make them.
Question 6. Are Toxic Chemicals Included In The Plastic Products We Buy?
The simple answer is ‘not intentionally’. The more thorough answer is that toxicity is a complicated subject. Salt, and even water, at too high an intake are toxic to humans. Both are necessary for health and neither is considered toxic. To be a risk, any toxic material must be delivered to sensitive organs in sufficient quantity to create an adverse result. Health risk is not created by mere presence alone.
Plastic products may contain many additives that are included to change appearance, such as colors, or to change performance, such as materials that make stiff plastics more limp and flexible. All additives for food packaging must pass stringent testing to meet FDA requirements for indirect food additives whether the additive actually is ingested or not4. Additives for other than food packaging have other requirements to meet. In general, if an additive becomes identified as problematic, alternatives are found and used. As for the plastic itself, manufacturers recognize it is in their best long-term interest to be sure the plastic as made create negligible risk.
Question 7. Why Are Plastics Used In Durable Goods?
Manufactured items defined with a useful life of more than three years, including automobiles, appliances, computers, etc., are called durable goods. Manufacturers of durable goods choose plastics for many reasons:
- The automotive industry chooses plastic for its durability, corrosion resistance, ease of coloring and finishing, resiliency, cost, energy efficiency, and light weight. Light weight translates directly into improved fuel usage experience and lowered costs to the consumer. Use of plastics in car bodies, along with improvements in coating technology, contribute to automobiles lasting much longer than vehicles did before the widespread use of plastics in fender liners, quarter panels, and other body parts.
- Major appliance manufacturers use plastics because of their ease of fabrication, wide range of design potential, and thermal, electrical, and acoustic insulation. Plastics characteristics can significantly reduce production and use energy consumption and greenhouse gas generation. Plastic insulation in refrigerators and freezers helps reduce operations costs to the consumer.
- The building and construction industry uses vinyl siding for homes because of its appearance, durability, ease of installation, cost, and energy efficiency.
- Plastics can reduce energy consumption for the auto, appliance, and building and construction industries, providing a substantial saving in production costs.
Question 8. What Is Plastic Film?
Stretchy plastic items such as carrier bags, bubble wrap, vegetable and food bags, cling film, crisp packets, magazine wrappers etc are all types of plastic film. Please refer to this plastic film leaflet which lists items that can and can’t be recycled in the red plastic and cans recycling box.
Question 9. Why Won’t You Collect Plastic Film For Recycling Anymore?
There are limited outlets to sell plastic film and sorting it from plastic bottles, pots, tubs and trays is very costly. Removal of film from our recycling will assist in maximising the council’s income from all material collected thus reducing costs to the council tax payer in these difficult financial times.
Question 10. Why Have I Not Been Told?
The change to Powys’ plastics and cans kerbside collection service has been communicated publically via press releases published in the local newspapers, advertising on the Powys County Council website and campaigns using social media online in the last few weeks. Full details were also included in the literature for the three weekly refuse collection service which were delivered to every household in Powys.
Question 11. Why Haven’t You Posted A Flyer Through My Door?
Powys County Council have not posted a door-to-door flyer campaign to communicate these changes as this incurs a large cost, produces additional paper waste and would be repeating the contents of the flyer sent late last year.
Question 12. How Much Is Going To Be Saved By Not Collecting Plastic Film?
Collecting plastic film means we have to pay third parties to take and sort our plastics before it is sent for recycling. Processing the material including plastic film costs the council up to £300,000 each year depending on the prevailing market conditions. By removing the film we should be able to sell our plastics direct to companies for recycling.
Question 13. What Should I Do With The Plastic Film Items?
The council encourages residents to reuse their plastic bags and save money as these now cost 5p each to purchase. Some supermarkets will also collect used bags for recycling.
Other plastic film items should not be placed in your red plastic and cans recycling box and instead placed in your wheeled bin or purple sacks. These items are not bulky and can be easily squashed to save space within your refuse.
Question 14. Can I Put Plant Pots In My Red Box?
No, unfortunately plastic plant pots are not one of the plastics we are able to take at the kerb side. They should be reused where possible or added to your wheeled bin or purple sacks.
Question 15. I Currently Collect All My Plastic Containers In A Bag In A Kitchen Bin And Then Put The Bag In My Red Box For Collection. Is This Still Ok?
No, it is important that the containers are put in the box loose as the bag itself is classed as contamination. If you use the net provided there shouldn’t be any problems of plastic blowing out of the box.
Question 16. What Happens If I Put Something In One Of The Recycling Boxes That Shouldn’t Be There?
If you do add something to your recycling box that shouldn’t be there, such as a crisp packet (that can’t be recycled), we will leave it behind in the box with a note attached explaining why we haven’t taken it – this way you’ll know what to do with it next time.
Question 17. Why Hasn’t My Plastic And Cans Recycling Box Been Emptied?
From June, boxes containing large amounts of plastic film will not be emptied and left at the kerbside for the householder to remove the plastic film and put the correct items out for collection on their next scheduled collection. A short leaflet detailing what items can and can’t be recycled in the plastic and cans box will be left along with an explanation why we haven’t taken it.
If your box is already full with items that can be recycled, you can take any additional items to be recycled at a community recycling site or household waste recycling centre. You can also request additional boxes. Plastic film items that we no longer collect should be placed in your wheeled bin or purple sacks.
Question 18. Why Should I Recycle? I’ve Heard It All Ends Up In Landfill?
The council sends all of what you put out for recycling each week to recycling facilities. The only material that will ever be disposed of will be contaminants. In 2015/16, Powys recycled nearly 59% of its waste.
Question 19. So, Will We Be Getting Less Of A Service Than In The Past?
We are providing far more collections than we used to.
Back in 2005, the council would collect one type of waste from every household once a week.
In 2016 the council collects:
- Plastic and cans, paper and card and glass recycling boxes every week
- Food waste kerbside caddy every week
- As well as the left over ‘non-recyclable’ rubbish in your wheeled bin or purple sacks every three weeks.
Question 20. What Happens If I Have Got More Rubbish Than Will Fit Into My Wheeled Bin?
When putting it out for collection, the lids of the wheeled bin must always be fully closed. Rubbish that doesn’t fit inside the bin or left on the floor next to it will not be taken.
Most households will have plenty of space in their residual waste bin providing they recycle everything they can every week – paper, card, plastics, cans, glass and food waste.
Question 21. Why Doesn’t The Council Recycle More Materials At The Kerbside?
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?
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. Thermoset Polymers Are Very Useful In The Manufacture Of Electrical Fittings. Name A Thermoset Polymer Used For This Purpose?
Urea Formaldehyde (UF).
Question 24. Describe The Properties Of The Polymer You Have Named Above That Make It Suitable For Electrical Fittings?
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 25. Explain The Term ‘thermoplastic’, With Reference To Molecular Structure?
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 26. Thermoplastics Are Very Useful In The Manufacture Of Mobile Phone Casings. Name A Thermoplastic Used For This Purpose?
Question 27. Describe The Properties Of The Polymer You Have Named Above That Make It Suitable For Mobile Phone Casings?
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 28. Are Plastics Eco-friendly?
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 29. How Do We Judge Whether Plastics Are Eco-friendly In Relation To Other Materials?
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 30. Are Plastics Responsible For Utilising A Major Share Of The World’s Oil Or Hydrocarbon Resources?
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 31. Do Plasticss Make-up A Large Part Of The Municipal Solid Waste?
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.
Question 32. Do Plastic Grocery Bags Block Drains During The Rains?
Unlikely.Plastic grocery bags are lighter (less dense) than water; hence, they float. This is why they accumulate on the beaches when disposed indiscriminately. In the case of a vertical grill in the drainage system, the water will flowthrough the grill with the plastic bags floating on the surface. In the case of a horizontal grill such as the one found on the roadside, the bags will be displaced by flowing water. By applying this logic, it is difficult to understand how plastic grocery bags are responsible for blocking drains. Perhaps, someone should carefullyobserve and determine what is the real porblem.
Question 33. Are Plastics Toxic When Used In Contact With Foods And Medicines?
NO. Plastics are used world-over because they are safe for packaging of foods, medicines and child care products. A few examples are – milk pouches, edible oil container, ice-cream packs, blister packs for tablets and capsules.I.V.fluids and blood is collected and stored in plastic bags.
While plastics are safe for packaging of food and medicinal products, there are standards in each country,which specify the type of Additives and Pigments, which can be used safely for contact with foods.
Question 34. Are Plastics Hazardous When Buried In Land-fills?
NO. Plastic waste is pre-dominantly eco-neutral or inert. It does not generate toxic leachates which contaminate the soil or ground water resources. On the contrary, those products which do biodegrade with by-products,may result in contaminating ground water resources.
Plastic consumer waste is easily compactible, and occupies less space inland-fills.
The fact that plastic waste is inert and does not biodegrade, makes segregation and recycling a more logical approach to waste managment, for urban areas.
The famous study on excavation of New York’s land-fills by the University of Arizona, U.S.A., reveals that fooditems, such as beef-stakes, corn-on-cob, news papers – things which you might expect to biodegrade in a fewyears, are in recognisable form after 30 years. This is because, anaerobic biodegradation (in the absence of airand sun-light) is an extremely slow process. This process also generates methane gas from land-fills – which for its “green-house” effect is worse than carbon dioxide.
Question 35. Does The Burning Of Plastic Generate Toxic Fumes?
NO. To a large extent, post-consumer waste is made up of grocery or polyethylene bags. The chemical structure of polyethylene is made up only by carbon & hydrogen atoms. Anyone, who has done elementary chemistry will know that burning a carbon hydrogen molecular chain will generate carbon-dioxide and water vapour.
A product made from PVC, when burnt in an open fire will emit hydrogen chloride fumes which are pungent. In fact this property has a singnificant advantage in retarding propagation of a flame when used as a sheath in a
power cables. Normally a PVC product or a post consumer pack is extremely rare, in Municipal solid waste.
The toxic fumes which the public wrongly believe are generated from plastics, are the result of burning materials contained in the bag, to get ride of industrial wastes.
Question 36. Are Plastics Harmful To Plant Growth, When Buried In The Soil?
NO. The use of polythylene nursery bags for growing seedlings for plantation crops or for afforestation is an application which is widely previling all over the world. The thin polyethylene bag holding the soil and sapling is slit with a blade and covered by soil. This way the root zone of the young sapling is not disturbed. In the conventional method the sapling had to be uprooted from a bamboo wicker basket, which increased the mortality rate of the young sapling.
Plastics are inert and their presence under the soil has no affect on the soil chemistry or plant growth.
Question 37. Should We Change Over From Plastic To Paper Bags?
A decision should be made after considering these facts.
The wide spread belief that substitution of plastics with paper is more favourable to the environment, is not supported by facts and a L.C.A.
The manufacture of paper bags requires two-and-half times the energy as compared to plastic bags of the same size and for comparable performance.
The manufacture of paper produces singnificantly higher air pollutants. There is a huge disparity in waste water discharge in manufacture or recycling of paper.
As far as biodegradability is concerned, the University of Arizona study shows that newspapers burried in 1952 in land-fills and excavated in 1989, were legible. The same observation was made with telephone directories.
Some will argue that paper comes from trees which is a renewable resource; while plastic is manufactured from oil, which cannot be replaced. The argument against this is, that forests play an important role in protecting our soil bank and maintaining the gaseous balance in our atmosphere, by absorbing carbon dioxide and in turn releasing oxygen. In our hunger for wood, 44 million hectares of forests have been felled since Independence, making this country a land with one of the lowest areas under forest cover (area under forest to total land area). Therefore, as far as India is concerned land is not a renewable resource.
Question 38. Do Plastics Meet The Criteria Of Resource Conservation; – Do We Get “more For Less” While Using Plastics Packaging?
YES, Let us take the example of the humble plastic grocery bag whcih has been denigrated so extensively in the media. A stack of 2000 plastic grocery bags will be seven-and-half INCHES high; a stack of 2000 paper grocery bags will have a height of seven-and-half feet. Imagine what this means in terms of transportation, and the increase in exhaust emissions.
A study conducted by the “German Society for Reasearch in the Packaging Market”, shows that if plastics packaging were replaced with other materials, the weight and volume of disposables would increase by a factor of 4 and 2.5 respectively, along with twice the level of energy consumption and double the cost of packaging.
Another good example is the transport of mineral water in light weight PET bottles. A truck can carry 60% more water with 80% less packaging, as compared to glass bottles; this results in fuel savings of almost 40%.
The ratio of product weight packed to the weight of package is the highest for plastics packaging; for example 500 gms of coffee can be packed in a glass jar weighing 500 gms, or a tin plate container weighing 130 gms, or a plastic laminated pouch weighing only 12 gms. Still better, one kg of salt is packed in a pouch weighing 5 gms where the ratio of product weight to package weight is 200:1. These are some examples of getting “more from less” through plastics packaging.
Question 39. What About The Role Of Plastics In Improving The Qualify Of Life?
According to a UNICEF report, in our Country an estimated 2500 children die every day of diarrhoeal diseases, caused by polluted drinking water and lack of sanitation. Those who survive, continue to suffer from water borne diseases and the country loses a staggering 1800 million man hours per year.
The target the country has set for itself, provides one safe source of drinking water per village. Such a difficult task would be impossible to achieve without the use of PVC pipe which is economical, light, easy to transport and install, but more significantly, uses 88% less energy in terms of “oil equivalent” in its production and use, for comparable performance with GI pipes.
The growth of personal products in the rural areas has increased dramatically. The growth of shampoos in bottles is at a level of approx. 2% year-on-year, whereas the growth is around 30% year-on-year for shampoos in flexible packaging and the small pack size, makes a product affordable to much larger section of the community and thereby promotes hygiene and personal care.
Question 40. Who Should Take Responsibility For The Plastics Environmental Issue?
We all share the responsibility for environmental issues. Any issue which concerns and community, has to be resolved with the co-operation of all involved; it is a “shared responsibility”. Those involved are Government, Municipalities, the raw material manufacturers, the retailers, and consumers.
Because domestic waste is a mixture of materials of which plastics is only a small component, under 2% by weight, it is the responsibility of government to manage waste and a regulate its disposal.
It is the responsibility of the plastics raw material and packaging manufacturers to come up with the most cost efficient solutions, which will preserve and protect goods, minimise the use of energy and reduce the weight and volume of waste. Food and personal product manufacturers, retailers and consumers need to be aware of the benefits of plastics pacakging and the need to dispose plastics in a manner which leads to increasing emphasis on recycling.
Production Planning and Control Interview Questions
Production Interview Questions
Maintenance and Manufacturing Interview Questions
Production Engineer Interview Questions
Manufacturing Industries Interview Questions
Production Planning and Control Interview Questions
Polymer Chemistry Interview Questions
Production Supervisor Interview Questions
Production Interview Questions
Good Manufacturing Practice (GMP) Interview Questions
Maintenance and Manufacturing Interview Questions
Production Engineer Interview Questions
Manufacturing Industries Interview Questions
Polymer Chemistry Interview Questions
Production Supervisor Interview Questions