The baristas know me by name, embarrassing. I had a mini internal physiological earthquake as I approached the counter. For years, I have eagerly awaited this moment! But do these Starbucks reusable plastic cups represent a true green marketing revolution — or are they just a green marketing ploy?
Have you ever wondered why some plastic bags are stronger than others? Why bags from clothing stores at the mall tend to be strong and thick, whereas those from your local grocery store are flimsy and thin? And then there are those wispy, clear bags you get back with your dry cleaning.
There are many types of plastic bags, all designed for different purposes. The plastics we use today have come a long way since Alexander Parkes first introduced them to the world at London's Great International Exhibition in Parkes's material was an organic derivative of cellulose that could be molded when heated and then maintained its shape upon cooling.
But it wasn't until that the word "plastic" was coined. Baekeland used the term to describe a new class of materials that included "bakelite," a substance he created from coal tar.
Bakelite was used to produce many items, including telephones, cameras, and even ashtrays.
Although a key component in these items, plastics did not become really popular until after World War I, when petroleum, a more easily processed substance than coal, became readily available. Petroleum and natural gas are the primary sources of the key ingredients in plastic.
Plastics are composed of polymers--large molecules consisting of repeating units called monomers. In the case of plastic bags, the repeating units are ethylene, or ethene.
When ethylene molecules are polymerized to form polyethylene, they form long chains of carbon atoms in which each carbon also is bonded to two hydrogen atoms.
Many kinds of polyethylene can be made from ethylene. Plastic bags typically are made from one of three basic types: The major difference between these three materials is the degree of branching of the polymer chain.
Branching can influence a number of physical properties including tensile strength and crystallinity. The more branched a molecule is, the lower is its tensile strength and crystallinity.
That's why garment bags from the dry cleaner are so weak and flimsy. They are made from highly branched LDPE. Another difference among these types of plastics is the method in which they are made. For a long time, Ziegler-Natta polymerization was the only way to produce linear unbranched polyethylene.
Recently, a new way of producing polyethylene has become available: Like the Ziegler-Natta method, the metallocene method uses metal complexes as catalysts and is often used to make novel copolymers. LDPE, the branched polyethylene, is made by a different process called free-radical polymerization.Starbucks, bending to growing environmental concerns, will eliminate plastic straws by The move by the ubiquitous java joint will affect its more than 28, stores, it said Monday.
Polyethylene is classified by its density and branching. The scientific name polyethene is systematically derived from the scientific name of the monomer. The alkene monomer converts to a long, Look up polyethylene in Wiktionary, the free webkandii.comg point: – °C (– °F; – K).
Polyethylene: Polyethylene (PE), light, versatile synthetic resin made from the polymerization of ethylene. Polyethylene is a member of the important family of polyolefin resins. It is the most widely used plastic in the world, being made into products ranging from clear food wrap and shopping bags to detergent.
Plastic is one of the most widely used materials both in terms of domestic and industrial products. It is also known as the most brilliant innovation of the millennium. This article discusses some of the common polymers, their properties and applications.
Polyethylene - its properties and uses 1. ADVANCING THE TECHNICAL KNOWLEDGE OF MAINTENANCE TRADESMEN AND PLANT OPERATORS POLYETHYLENE – ITS PROPERTIES AND USES ABSTRACT crystalline alignment.
What is Polypropylene (PP), and What is it Used For? Polypropylene (PP) is a thermoplastic “addition polymer” made from the combination of propylene monomers. It is used in a variety of applications to include packaging for consumer products, plastic parts for various industries including the automotive industry, special devices like living hinges, and textiles.