Plastic objects

Approximately 4500 tons of sodium hypophosphite [7681-53-0] NaH2P02, was produced in 1990. This material is used principally in electroless nickel plating of plastic objects. Of the secondary products made from primary phosphoms compounds, phosphoms oxychloride is manufactured in the largest volume. Phosphoms pentachloride and phosphoms sulfochloride are made from phosphoms trichloride. 

The first reports of plastic in the North Atlantic indicated the presence of 50-12,000 particles/km in the Sargasso Sea in 1972 (52) and from 0-14.1 particles per m in coastal waters of southern New England (42), where the main source was river-borne effluents from plastic fabrication plants (44). Plastic objects discarded from boats and from recreational activities on beaches were the main sources of debris in Narragansett Bay, being deposited at a rate of 9.6 g m of beach front per month (53). During a detailed survey off the southeast coast of the United States (43, 54), fragments of plastic were present in about 70% of the samples collected from the waters of the continental shelf, the continental slope and the Gulf Stream between Florida and Cape Cod, 50% of those from the Caribbean Sea, and 60% of those from the Antilles Current. Since unprocessed plastic was more prevalent in continental shelf waters and fabricated objects were common offshore but rare near land, the authors surmised... 

An "amazing amount of trash", mostly plastic objects, is stranded on the Atlantic coast of Florida during onshore winds, particularly in winter (55). While some of this debris was of United States origin (from local sources or from entrainment in the Florida Current of wastes from shipping), the remainder was of Venezuelan, Columbian, and Jamaican origin. Debris from the easternmost Caribbean and the northern coast of South America could be transported to the Atlantic coast of Florida by the Guiana and Antilles Currents in about four months. Alternatively, debris from the southern or southwestern part of the Caribbean could be carried by the Caribbean Current via the Yucatan Channel and Straits of Florida to the Atlantic coast of Florida in as little as two months. 

One of the most important reactions in the chemical industry is the cracking (removing hydrogen) of paraffins to form olefins. Olefins are essential starting materials for many common products that we all use, particularly plastics. The simplest olefin is ethylene, which can be polymerized (reacted many times with itself) to give po/yethylene used for bottles, dishware, film, etc. The next higher olefin, propylene, can be polymerized to polypropylene used in the manufacture of rugs, toys, kitchenware, and many other plastic objects. Note that the names of olefins end in -ene, which denotes the presence of a double bond in the compound. 

The flexibility of some plastics can be improved by the addition of small molecules called plasticizers. For example, pure PVC turns brittle and cracks too easily to make useful flexible plastic products. With an added plasticizer, however, PVC can be used to make seat covers for automobiles, raincoats, garden hoses, and other flexible plastic objects. Plasticizers must be liquids that mix readily with the pol Tner. In addition, they must have low volatility so that they do not escape rapidly from the plastic. Dioctylphthalate is a liquid plasticizer that is formed by condensing two alcohol molecules with one molecule of phthalic acid, as illustrated in Figure 13-10. 

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. 

One solution to the problem of our overflowing landfills is to burn plastic objects instead of burying them. What would be some of the advantages and disadvantages of this practice ... 

Use other plastic things to bend the water. A plastic comb will work. Do some plastic objects move the stream of water more than others ... 

Children can be exposed to DEHP if they eat food or drink water contaminated with DEHP or if they breathe in the chemical from ambient or indoor air. Small children can also be exposed by sucking on or skin contact with plastic objects (toys) and pacifiers that contain DEHP, as well as by ingestion of breast milk containing DEHP. Children also can be exposed to DEHP if they undergo certain medical procedures that require the use of flexible tubing such as that used to... 

So how do we balance the increasing pressure to introduce even more plastic objects into our lives while minimizing the impact on our environment This is an extremely important question, one that we will address when we discuss issues surrounding the recycling and disposal of polymers in Chapter 9. 

Because of their low densities, most of the plastic objects released at sea remain on the surface, where they slowly break apart into smaller and smaller pieces. In fact, the surface of the ocean contains a large volume of plastic refuse, the most common man-made objects sighted. Much of it is in the BB-shot-to-fingernail size range. This phenomenon is significant enough that the term nurdle was created to describe these small pieces of plastic flotsam. Some of the nurdles are mistaken for food by animals such as turtles, fish, whales, and birds, whose stomachs often contain sizable amounts of plastic trash (Krajick 2001). One study estimates that the near-shore water off the beaches near Los Angeles contains more than one million nurdles per mile. 

J. Walker, What Causes the Color in Plastic Objects Stressed Between Polarizing... 

To form a plastic object by pouring a fluid monomer-polymer solution into an open mould where it finishes polymerising. Forming plastic film and sheet by pouring the liquid resin onto a moving belt or by precipitation in a chemical bath. 

Warpage Dimensional distortion in a plastic object after moulding. 

Methyl, ethyl, and benzyl ethers of cellulose are important in the production of textiles, films, and various plastic objects. 

ICI s Monastral Green GNA a good green for plastic objects... 

Find three plastic objects in your home that are labeled with a recycling code of 1. From what substance are these objects made Are objects of this type recycled in your town ... 

A survey of plastics-containing objects in the British Museum and the National Museum of Denmark showed that 1% of objects were actively deteriorating and were in immediate need of conservation, while 12% exhibited deterioration and required cleaning, stabilising and repair. All the acute objects contained cellulose nitrate, cellulose acetate, plasticised PVC or polyurethane foam. Most objects (60%) were defined as being of low conservation priority, that is, they were in a stable condition but needed some treatment such as cleaning. Only just over one quarter required no conservation treatment. In general, deterioration of plastic objects in museums is visible within 5-25 years of collection. 

Stress, fatigue and mechanical damage. These are results of the use of the plastic objects and could comprise frequent bending of a PVC soft toy leading to its failure or abrasion of the surface of a vinyl record as it is repeatedly pulled out of its sleeve to play, resulting in its inability to produce perfect sound. 

Deterioration of plastic objects in museums has only been recognised as an important area worthy of research since 1991, while the scope of the problems surrounding the preservation of modern art has only been appreciated internationally as recently as 1998. Little is known about the conservation of plastics compared to other materials found in museums. To date, few conservation practices have been established, and development of new treatments is far slower than most degradation processes. Once deterioration has started, it cannot be stopped or reversed, but only slowed. 

Specific preventive approaches to conservation have been used successfully to prolong the useful lifetimes of collections containing cellulose nitrate, cellulose acetate, PVC and polyurethanes. The microclimate surrounding plastic objects can be readily and cheaply controlled by introducing an adsorbent or scavenger into their storage areas. 

This is rather contra-intuitive. Museum conservators and designers are usually advised either to improve ventilation or to include adsorbent materials to remove volatile degradation products from the air space surrounding plastic objects during storage. This would accelerate the loss of plasticiser and thereby reduce the longevity of both new and deteriorated PVC objects. 

Figure 1.16 Codes for the identification of plastic objects by resin.

III. In contrast to the two cases described above, plasticity (plastic flow) reflects a non-linear behavior, i.e. proportionality between applied stress and deformation is no longer present. For idealized plastic objects, in which one can ignore any elastic deformation, the deformation does not occur at stresses lower than the critical shear stress (the yield stress, or the yield point), x, i.e. y = 0 and y = 0. When x = x the deformation starts to occur at a given rate, i.e., plastic flow, which does not require further noticeable increase in shear stress, begins (Fig. IX-6). 

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