Polyethylene Terephthalate Plastics

Polyethylene Terephthalate Plastics PET plastics or polyethylene terephthalate is used in many different products. The properties of PET makes it ideal for a number of different uses and these advantages make it one of the most common plastics available today. Understanding more about the history of PET, as well as the chemical properties, will allow you to appreciate this plastic even more. In addition, most communities recycle this type of plastic, which allows it to be used again and again. What are the chemical properties of PET? PET Chemical Properties This plastic is a thermoplastic resin of the polyester family and is commonly used in many different products, including synthetic fibers. It can exist in both a transparent and a semi-crystalline polymer, depending upon the processing and thermal history. Polyethylene terephthalate is a polymer that is formed by combining two monomers: modified ethylene glycol and purified terephthalic acid. PET can be modified with additional polymers as well, making it acceptable and usable for other uses. History of PET The history of PET began in 1941. The first patent was filed by John Whinfield and James Dickson, along with their employer, the Calico Printers Association of Manchester. They based their invention on the earlier work of Wallace Carothers. They, working with others, created the first polyester fiber called Terylene in 1941, which was followed by many other types and brands of polyester fibers. Another patent was filed in 1973 by Nathaniel Wyeth for PET bottles, which he used for medicines. Advantages of PET PET offers several different advantages. PET can be found in many different forms, from semi-rigid to rigid. This is largely dependent upon its thickness. It is a lightweight plastic that can be made into a number of different products. It is very strong and has impact resistant properties as well. As far as color, it is largely colorless and transparent, although color can be added, depending upon the product that it is being used for. These advantages make PET one of the most common types of plastic that is found today. Uses of PET There are many different uses for PET. One of the most common is for drink bottles, including soft drinks and more. PET film or what is called Mylar is used for balloons, flexible food packaging, space blankets, and as a carrier for magnetic tape or backing for pressure sensitive adhesive tape. In addition, it can be formed to make trays for frozen dinners and for other packaging trays and blisters. If glass particles or fibers are added to the PET, it becomes more durable and stiffer in nature. PET is largely used for synthetic fibers, also known as polyester. PET Recycling PET is commonly recycled in most areas of the country, even with curbside recycling, which is simple and easy for everyone. Recycled PET can be used in a number of different things, including polyester fibers for carpeting, parts for cars, fiberfill for coats and sleeping bags, shoes, luggage, t-shirts, and more. The way to tell if you are dealing with PET plastic is looking for the recycling symbol with the number 1 inside of it. If you are not sure that your community recycles it, simply contact your recycling center and ask. They will be happy to help. PET is a very common type of plastic and understanding its composition, as well as its advantages and uses, will allow you to appreciate it a little bit more. You most likely have lots of products in your home that contains PET, which means that you have the opportunity to recycle and allow your product to make even more products. Chances are you will touch different PET products over a dozen times today.

The Scientific Basis for Defining Seasons

The Scientific Basis for Defining Seasons Contrary to common belief, modern meteorology recognized that the beginning of any season is the day on which the sun passes over particular latitude rather than how cold or warm the following will be. Hashtag: #FirstDayOfFall Ancient and Modern Meteorology Meteorological phenomena such as storms, lightning, and thunder are often considered dangerous and frightening for many people. The ability to predict their occurrence in the past was valued in many cultures. In fact, there is a large body of literature that spans the ancient period dedicated to the prediction and explanation of meteorological and astronomical events including animal behavior.   The division of the year into seasons enables the ancient culture to select the proper time plowing, sowing, reaping, and harvesting, making voyages with ships, prepare and protect themselves for against the natural severity of the seasons. CAN SCIENCE GO TOO FAR? However, ancient meteorology was largely based on past experience or preservation of the events of past weather and their sequence, speculations on the relation between events and proximate causes, philosophy, appeal to the deities, and belief in personal weather-control and magic.   The practice was only changed in the mid 19th century when a collection of facts has been operated by electric–telegraph and now radiotelegraphy.   Although recording observation and discussing them from a philosophical point of view still remains to this day, meteorologist today have a multitude of facts and records to base their forecast and in creating a weather map. Weather and Seasons Weather maps are important tools for developing and explaining weather forecasts. They vary in scope as there are national, continental, and global weather maps. Surface weather maps commonly contain identified fronts; high and low-pressure areas and temperatures, wind strength and air pressure and often used to provide information on the present weather condition.   Forecast weather maps, as the name suggests, are computer generated maps to predict changes in the weather.   Meteorologist also developed short-term (18-36 hours) and long-term (5 days) maps that are updated daily. However, since weather condition is rapidly changing, the weather forecast may not always be accurate and mere honest guesses of the weather condition for a certain period of time. The above surface map illustrates four different fronts – cold, warm, stationary, and occluded.   Note that these fronts separate different air masses and associated with lower pressure. A meteorologist using this map will likely forecast that weather along the stationary front (points A and B) will be clear to partly cloudy. The weather condition in the cold front (points B to C) will be cold, rainy in green-shaded areas, and snowy in the white shaded areas. Contrary to common belief, modern meteorology recognized that the beginning of any season is the day on which the sun passes over particular latitude rather than how cold or warm the following will be.   For instance, the first day of summer in the Northern Hemisphere is June 21 or when the sun is at its highest position in the noonday sky or 23  ½ degrees north (N) latitude. Each day past June 21, the noon sun is slightly lower in the sky as 12 hours or more of daylight in the Northern Hemisphere begins to shorten. COMPUTER SCIENCE DIPLOMA THESIS By September 22, the sun is directly above the equator and the astronomical beginning of fall officially begins in the Northern Hemisphere.   Three months after the autumnal equinox, the sun on December 21, is further away from the tilted Northern Hemisphere where days are shorter and nights are longer.   On this day, the sun shines directly above latitude 23  ½ degrees S (Tropic of Capricorn) or the first day of winter in the Northern Hemisphere. The first day of spring occurs around March 20 or when the sun crosses the equator and moving northward.