Grocery Bag

Nearly all polymeric materials require the addition of antioxidants to retain physical properties and to ensure an adequate service life. The selection of an antioxidant or system of antioxidants is dependent upon the polymer and the anticipated end use. A product that will not be exposed to the elements for a long period of time such as polyethylene grocery bags does not need a long term stabilizer polyethylenes used to iasulate communication cable must be stabilized for many years of service. 

Bleaching is defined as any process that chemically alters pulp to increase its brightness. Bleached pulps create papers that are whiter, brighter, softer, and more absorbent than unbleached pulps. Bleached pulps are used for white or light colored paper. Unbleached pulp is typically used to produce boxboard, linerboard, and grocery bags. Of the approximately 65.5 million T (72 million tons) of pulp (including recycled pulp) used in paper production in the U.S. in 2000, about 50% is for bleached pulp.1... 

A polymer can be hard or soft, rigid or flexible. To make plastic objects, chemists and engineers first make the type ofpolymer they need based on the properties they re looking for. For example, a bicycle helmet needs a much tougher polymer than a grocery bag. Usually, the polymer is first made into very small pieces, in factories. These pieces are then melted and molded into tubes, sheets, or any other shape desired. 

A low density polyethylene LDPE cellophane, squeeze bottles, trash/grocery bags, diaper lining... 

A meter stick or yardstick Two grocery bags Five pieces of string... 

It s been banned for use in paint since 1978, but lead (a naturally occurring heavy metal) still shows up in gasoline, PVC plastic, pipes, ceramic glazes, caulk, and old paint. These days it s also used in the production of batteries, ammunition, metal products (solder and pipes), devices to shield X-rays, and computer monitors (to block radiation). It s added to certain kinds of plastic, such as vinyl blinds, as well as the ink on plastic grocery bags. Developing babies can be exposed to lead in the womb. 

With Chapter 2, What Are They you can use a long list of covalent molecules to explain covalent bonding i the context of something as ubiquitous as a plastic grocery bag. You can also use polymer reactions as examples of composition reactions. 

Polyethylene is probably the material one encounters most abundantly in daily life, such as in the form of grocery bags, shampoo bottles and toys, but now one also finds it as the material in such super high performance products as bullet-proof vests. For such a... 

High density polyethylene, HOPE, is used for grocery bags, car fuel tanks, packaging and piping. 

Synthetic polymers are perhaps more vital to the fabric of modern society than any other group of compounds prepared in the laboratory. Nylon backpacks and polyester clothing, car bumpers and CD cases, milk jugs and grocery bags, artificial heart valves and condoms—all these products and innumerable others are made of synthetic polymers. Since 1976, the U.S. production of synthetic polymers has exceeded its steel production. Figure 30.1 illustrates several consumer products and the polymers from which they are made. 

K Using scotch tape, make a tube out of a paper grocery bag about 2 long by I" wide. Cut a 1" circle of paper and tape it to one end. 

Before the pulp can be made into paper, it is necessary to mechanically beat or refine it. It is also usually bleached with chlorine and calcium hypochlorite. Unbleached kraft pulp is used for grocery bags and heavy wrapping paper. Other materials may also be added to the pulp depending on the type of paper to be made. For book paper, fillers such as white clay and titanium oxide may be added to provide opaqueness and extra whiteness. Size may be added for stiffness and smoothness. Dyes are added for tinted papers. The specific combination of pulp and additives used to produce a particular type of paper is called the furnish for that paper. With better grades of paper, care is taken to produce a furnish that is chemically neutral (pH 7 on the acid-base scale). For a paper to have long life, it must be acid-free. 

We went out to a known Psilocybe haunt and out of rotting cow manure picked a paper grocery bag full of them. On that occasion and all hunts afterward I noticed that I had to be somewhat detached. It was as if they presented themselves only if I were not too greedy to find them. 

Density Why is it easier to lift a grocery bag full of paper goods than it is to lift a grocery bag full of soup cans The volumes of the grocery bags are identical. Therefore, the difference in effort must be related to how much mass is packed into the same volume. Density is a ratio that compares the mass of an object to its volume. The units for density are often grams per cubic centimeter (g/cm ). 

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