Category Science

What are invasive species?

Invasive species are organisms that migrate to or are introduced to a new geographical location, where they pose a threat to the environment. They could be insects, plants, animals or pathogens. These species start to grow and multiply quickly in the absence of natural predators from their original homes.

Invasive species are capable of causing extinctions of native plants and animals, reducing biodiversity, competing with native organisms for limited resources, and altering habitats. This can result in huge economic impacts and fundamental disruptions of coastal and Great Lakes ecosystems.  The impacts of invasive species on our natural ecosystems and economy cost billions of dollars each year. Many of our commercial, agricultural, and recreational activities depend on healthy native ecosystems. They can harm the environment, the economy, or even human health. Species that grow and reproduce quickly, and spread aggressively, with potential to cause harm, are given the label “invasive.”

 

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PLASTICS AND THEIR HISTORY

          The first plastic-type material was unveiled by Alexander Parkes at the Great International Exhibition in London in 1862. Parkes claimed that his new material could do anything that rubber was capable of, but at a much lower price. This material could be moulded into thousands of different shapes.

Cellophane

In 1913, Dr Jacques

Edwin Brandenberger invented a wipeable surface by adding a clear, flexible film to cloth. Brandenberger invented cellophane. Now it is widely used for packaging and is a fully flexible, waterproof wrap.

Bakelite telephone

In 1907, a New York chemist, Leo Bakeland, created a liquid resin which he named Bakelite. This resin could be moulded into any shape and it would not burn, boil or melt when it was set. Bakelite was the first thermosetting plastic which would always keep its shape and form.

V Kevlar

In a laboratory in 1965, two research scientists created a new fibre. They named it Kevlar. It was strong, light and flexible. Today it is used for sports equipment, bullet-proof vests and for ropes used on the expedition to Mars.

Nylon stockings

In 1939, nylon stockings were unveiled and were extremely popular with many women during the war years (1939-1945). Nylon replaced animal hair in toothbrushes, and silk in stockings.

Velcro

In 1957, George de Maestral was so impressed with the way that cocklebars — a type of vegetation — used thousands of tiny hooks to cling to anything, he invented a product, using nylon, that would replicate this natural phenomenon. He called it Velcro.

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PLASTICS AND THEIR USES

          Plastics have so many uses and many also have different names. These names include the brand names, trade names, manufacturers’ names and the inventor’s name. The unique characteristics of plastics mean that an enormous variety of products can be made, such as hard and flexible sheets, foams and fabrics as well as moulded objects. Plastics are an important part of everyday life.

          The world is full of plastics. Whether you realize it or not, practically everything you see and use on a daily basis is entirely or partly plastic material. Your television, computer, car, house, refrigerator, and many other essential products utilize plastic materials to make your life easier and more straightforward.  However, all plastics are not made alike. Manufacturers utilize a variety of different plastic materials and compounds that each possesses unique properties. 

1. Acrylic or Polymethyl Methacrylate (PMMA)

Well-known for its use in optical devices and products, acrylic is a transparent thermoplastic used as a lightweight, shatter-resistant alternative to glass. Acrylic is typically used in sheet form create products such as acrylic mirrors and acrylic plexiglass. The transparent plastic can be made colored and fluorescent, abrasion-resistant, bullet-resistant, UV-tolerant, non-glare, anti-static and many more. In addition to being than glass and polycarbonate sheeting acrylic is seventeen times more impact resistant than glass, easier to handle and process, and has endless applications.  

2. Polycarbonate (PC)

Tough, stable, and transparent, polycarbonate is an excellent engineering plastic that is as clear as glass and two hundred and fifty times stronger. Thirty times stronger than acrylic, clear polycarbonate sheets are also easily worked, molded, and thermo-formed or cold-formed. Although extremely strong and impact-resistant, polycarbonate plastic possesses inherent design flexibility. Unlike glass or acrylic, polycarbonate plastic sheets can be cut or cold-formed on site without pre-forming and fabrication. Polycarbonate plastic is in a wide variety of products including greenhouses, DVDs, sunglasses, police riot gear, and more.             

3. Polyethylene (PE)

The most common plastic on earth, polyethylene can be manufactured in varying densities. Each different density of polyethylene gives the final plastic unique physical properties. As a result, polyethylene is in a wide variety of products.  

  • Low-Density Polyethylene (LDPE)

This density of polyethylene is ductile and used to make products like shopping bags, plastic bags, clear food containers, disposable packaging, etc.  

  • Medium-Density Polyethylene (MDPE)

Possessing more polymer chains and, thus, greater density, MDPE is typically in gas pipes, shrink film, carrier bags, screw closures, and more.

  • High-Density Polyethylene (HDPE)

More rigid than both LDPE and MDPE, HDPE plastic sheeting is in products such as plastic bottles, piping for water and sewer, snowboards, boats, and folding chairs.    

  • Ultra High Molecular Weight Polyethylene (UHMWPE)

UHMWPE is not much denser than HDPE. Compared to HDPE, this polyethylene plastic much more abrasion resistant due to the extreme length of its polymer chains. Possessing high density and low friction properties, UHMWPE is in military body armor, hydraulic seals and bearings, biomaterial for hip, knee, and spine implants, and artificial ice skating rinks. 

 

4. Polypropylene (PP)

This plastic material is a thermoplastic polymer and the world’s second-most widely produced synthetic plastic. Its widespread use and popularity are undoubted because polypropylene is one of the most flexible thermoplastics on the planet. Although PP is stronger than PE, it still retains flexibility. It will not crack under repeated stress. Durable, flexible, heat resistant, acid resistance, and cheap, polypropylene sheets are used to make laboratory equipment, automotive parts, medical devices, and food containers. Just to name a few.  

5. Polyethylene Terephthalate (PETE or PET)

The most common thermoplastic resin of the polyester family, PET is the fourth-most produced synthetic plastic. Polyethylene Terephthalate has excellent chemical resistance to organic materials and water and is easily recyclable. It is practically shatterproof and possesses an impressive high strength to weight ratio. This plastic material is in fibers for clothing, containers for foods and liquid, glass fiber for engineering resins, carbon nanotubes, and many other products that we use on a daily basis.  

6. Polyvinyl Chloride (PVC)

The third-most produced synthetic plastic polymer, PVC can be manufactured to possess rigid or flexible properties. It is well-known for its ability to blend with other materials. For example, expanded PVC sheets are a foamed polyvinyl chloride material that is ideal products like kiosks, store displays, and exhibits. The rigid form of PVC is commonly in construction materials, doors, windows, bottles, non-food packaging, and more. With the addition of plasticizers such as phthalates, the softer and more flexible form of PVC is in plumbing products, electrical cable insulation, clothing, medical tubing, and other similar products.  

7. Acrylonitrile-Butadiene-Styrene (ABS)

Created by polymerizing styrene and acrylonitrile in the presence of polybutadiene, ABS is robust, flexible, glossy, highly processable, and impact resistant. It can be manufactured in a range of thicknesses from 200 microns to 5mm with a maximum width of 1600mm. With a relatively low manufacturing cost, ABS plastic sheeting is typically used in the automotive and refrigeration industries but is also in products such as boxes, gauges, protective headgear, luggage, and children’s toys.  

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HOW DOES PLASTIC ENVIRONMENT?

Plastics are derived from natural resources — oil, coal and natural gas. We are using oil so fast that the Earth’s supplies may run out within 100 years. If they do, so will plastics. Scientists are investigating new ideas for making plastics by processing plants such as the sweet potato, bamboo and flax. .61 Using organic raw materials to make plastics would be kinder to the environment. Items such as a car would be easier to dispose of. If a car was made of organic raw materials most of the parts would naturally rot. Instead of scrapping it, you may just end up eating it!

Wildlife

Plastics can be extremely hazardous to wildlife. Each year, many birds become entangled in plastic drinks can holders. Once the plastic is wrapped around a bird’s neck or feet, it is difficult to escape. This causes panic and, ultimately, death.

Pollution

 The Trabant emerged in the 19505 as one of the first cars to be made almost entirely out of plastic. While its benefits included value for money and a vehicle that would not easily rust, it also had its downfalls. The plastic used on this car would not breakdown naturally in the environment and so disposal was difficult. Unfortunately, the Trabant added to the mass waste in landfill sites.

Re-using

Large water containers like these can be re-used many times. This is far more considerate to the environment than disposing of numerous smaller bottles each time you have a drink. it’s also a good idea to donate old computers, compact discs, video tapes, toys and household goods to charity shops for re-use.

Alternative sources

Plastics are made from natural resources that are not renewable. These resources are rapidly running out. Alternative sources such as soya beans and sugars can be processed into plastic products, saving our valuable non-renewable sources.

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WHAT IS THE PLASTIC RECYCLING?

        We throw away millions of tonnes of plastics every year. Plastics make up about one-tenth of the weight of waste thrown away. Most of this is buried as landfill rubbish under layers of earth. Many plastics do not rot or break down naturally. This means that plastic rubbish will remain on our planet for a very long time.

       Recycling is the process of re-using waste materials to make new products. However, recycling plastics is complicated. Different types of plastic need to be processed in different ways. Some plastics can be melted and used to make more plastic products such as bags and bottles. Others can be made into fibres for clothing. Some can be burned as fuel in the recycling process.

Recycling process

Collection

Plastics are available in a number of forms for example plastic containers, jars, bottles, plastic bags, packaging plastic, big industrial plastics just to mention but a few. Due to their nature and availability, there are plastic collection centres and some business people have ventured into plastic collecting business as a source of income. Tons and tons of scrap plastic are collected and sent to a collecting yard where they are then packed and transported to plastic processing plants. Unfortunately, not all countries have the capacity to recycle plastic. Very few developing countries can actually recycle plastic. This means that, plastic waste is still a major problem to some countries in the world.

2. Sorting

The actual plastic recycling process starts with sorting of the different plastic items by their resin content and color. This process is also done to ensure all contaminates are eliminated. There are specially designed machines that help in sorting of the plastics according to their resin content. Then the recycling mill sorts the scrap plastic by symbols at the bottom of the plastics.

3. Shredding

After sorting the plastics, the next step is to cut the plastics into tiny chunks or pieces. The plastic bottles and containers are then ground and cut into tiny pieces or flakes. The heavier and lighter plastic flakes are separated using a specially designed machine. The separation process helps in ensuring that the different plastics are not put together or mixed up in the final product. Remember that different plastics are used to make different items.

4. Cleaning

After a complete separation, the flakes or chunks are then washed with detergents to remove the remaining contamination. Once the cleaning process is complete, the clean flakes are passed through specialized equipment that further separates the plastic resin types. The plastic flakes are then subjected to moderate heat to dry.

5. Melting

The dry flakes are melted down. They can be melted down and molded into a new shape or they are melted down and processed into granules. The melting process is done under regulated temperatures. There is specialized equipment designed to melt down plastic without destroying them.

6. Making of pellets

After the melting process, the plastic pieces are then compressed into tiny pellets known as nurdles. In this state, the plastic pellets are ready for reuse or be redesigned into new plastic products. It is important to point out that recycled plastic is hardly used to make identical plastic item or its previous form. It is in this pellet form that plastics are transported to plastic manufacturing companies to be redesigned and be used in making other useful plastic products.

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What are Synthetic Fibers?

Plastics are used to make synthetic fabrics for clothes, curtains, sheets and carpets. Nylon, polyester and acrylic are all plastic fabrics. They are made from thermoplastics. You may wonder why it is necessary to make synthetic fabrics when there are natural ones, like cotton and wool. The answer is that natural fabrics from raw materials are expensive and in short supply.

Clothes made from synthetic fabrics have other advantages such as they do not crease much. However, they are not so comfortable to wear, or as warm, as natural fabrics. Synthetic fabrics are often mixed with natural ones to combine the advantages of both.

A Synthetic Fibre is a chain of small units of chemical substance joined together. Many such single units combine to form single unit called Polymer. Polymer means made of many units joined together.

 Types of Synthetic Fibre

       Rayon– Rayon is synthesized from wood pulp. Rayon resembles silk, so it is also known as artificial silk. Rayon can be dyed in different colours and is much cheaper than silk.

       Nylon– Nylon was first commercially synthesized fibre. Nylon is synthesized from coal, water and air. Nylon is very strong and its fabric is like silk.

       Polyester– Polyester, one of the most popular man-made fibres. It is made of repeating unit of a chemical called ester. It is widely used to make clothes.

       Acrylic– Acrylic is a man-made fibre. Acrylic is known as artificial wool or synthetic wool because it resembles wool. Acrylic is cheaper than natural wool and can be dyed in various colours. This makes acrylic is very popular among other fabrics.

Characteristics of Synthetic Fibres

       Synthetic fibres are cheaper than natural fibre.

       Synthetic fibres are stronger than natural fibre.

       Synthetic fibres are more durable than natural fibre.

       Synthetic fabrics are dried up in less time.

       Synthetic fibres are easy to maintain and wash.

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