Plastics in general

All the national and regional French press, public and professional, was included in the constitution of the corpus (news excluded). The research was conducted for the month of March 2011. It resulted in a number of articles, 355, of which the vast majority were in the regional press (83%) and a minority were in the national press (17%). Similarly, most of the articles were published by the mainstream press, with a few pubhshed by other media. 

The category of business life which discusses the productive situation (for example, the economic situation, the market position and the cessation of activity) or the social situation (for example, strikes) is also present, with 17% of articles. 

Articles in the national press are fotmd mostly in the business press (Les Echos, La Tribune, L Agefi quotidien) and address the economic situation of enterprises producing or working with plastics (for example, the increase in raw material prices and their impact on the price of plastic, innovations in the field of plastics), with only a few articles in the mainstream press  

Volimtaiy corporate actions, identified as limiting the environmental effects of plastics, are mentioned in 4% of the articles, but the message of an environmental nature is difficult to separate from the message with commercial advertising purposes. 

The categories identified are 1. waste collection including plastics 2. business Ufe 3. green chemistiy companies 4. educational activities around recycling waste including plastics 5. educational activities around chemistry where the issue of plastics is addressed 6. artistic actions enhancing plastics 7. substances considered to be toxic contained within plastics 8. contribution of plastics to sustainable development 9. chemical accidents involving plastics or occupational toxicity in the production of plastics 10. call for waste collection  

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The business climate of the 1990s is different from the past. Factors such as increased competition, a global marketplace, rapid technical shifts, and greatly compressed product life cycles constantly open new opportunities for plastics in general and reinforced plastics in particular. Reinforced plastics have become widely accepted for particular appHcations because they offer a combination of design, performance, and economic benefits to the user. These materials have had a proven record of success since the 1940s. 

Conversely, at strains above the first damage limit recovery will be incomplete and permanent deformation should be expected and accounted for in the evaluation. This is true not only for plastics in general but also of reinforced plastics. When RPs are stressed... 

One of the most common impurities in coastal areas which acts in a chemical manner rather than a physical one is salt water. However, with the ever-increasing spread of the chemical industries, and the stepped-up use of gasoline powered vehicles, the problem of chemical degradation are also of interest particularly in inland areas. While plastics in general are corrosion resistant, the multiplicity of chemical agents which can be in the air in industrial atmospheres, plus the chemical nature of the various plastics indicates that it cannot be assumed that all plastics are chemically resistant to all atmospheres. 

The results of the tests to determine the calorific power show satisfactory values for coprocessing, be it for mixed materials, otherwise unusable material from separation or plastics in general. As observed by [6], the level of chlorides is closely related to the quantity of plastics in the mixture, and also depends on the type of plastic. 

The degradation of composites has been reviewed by Bank and co-workers [1] and in the work at the National Physical Laboratory (see Section 12.11). Apart from the special circumstances of damage accumulation in fatigue, the models are the same as those applying to plastics in general. 

Dimensional Stability. Plastics, in general, are subject to dimensional change at elevated temperature. One important change is the expansion of plastics with increasing temperature, a process that is also reversible. However, the coefficient of thermal expansion (CTE), measured according to ASTM E831, frequendy is not linear with temperature and may vary depending on the direction in which the sample is tested, that is, samples may not be isotropic (Fig. 7). 

The method of fabrication for plastic items is influenced by whether or not one is dealing with a thermoplastic or a thermosetting plastic. In general, the first group may be heat-sealed, heat-molded, and solvent-cemented, but these possibilities are not available for the thermosetting resins. Both groups generally can be machined. 

Plasticizer. In general, propellant formulations include plasticizers, which are nonreactive... 

Heat transfer limitations are important restrictions for pyrolytic processes because of the low thermal conductivity of plastics. In general the heat flow from the surface of a plastic particle to its core (internal heat flux) is rather slow compared with the heat flow... 

We have not given compositions of complete plastics in general, but you might like to know the typical composition of a motor tyre. Notice that the ratio of sulfur to rubber is about 1 40—that gives an idea of how many cross-links there are. Notice also that the rubber contains a great deal of carbon to Improve the wear of the rubber. The roles of the other materials are explained in the table. 

Plastics in general (including all forms) are sensitive to high temperatures, among the more resistant being fluorocarbon resins, nylon, phenolics, polyim-ides, and silicones, though even these soften or melt above 260C. Other types (cellulosics, polyethylene, acrylic polymers, polystyrene) are combustible when exposed to flame for a short time and still others (polyurethane) burn with evolution of toxic fumes. 

It is not easy to define the term plastic , which is usually considered as equivalent to the term polymer. Plastics are polymeric materials, but not all polymers are plastics. In general, the term plastic is used to refer to any commercial polymeric material other than fibres and elastomers. Moreover, commercial plastics include other components such as additives, fillers, and a variety of compounds incorporated into the polymers to improve their properties. The term resin is usually used to describe the virgin polymeric material without any of these components. 

Polymer. There is a natural tendency for polymer scientists to assume that the relationships between polymer structure and properties carry over from the solid polymer to its foams as well. To some extent this is true. For example, the effects of plasticizers in vinyls and the effects of cross-linking in urethanes are well understood in the solid polymers, and they have parallel effects in the foamed plastics. In general, the properties of polymers in the solid phase can be reflected in their foams in the following ways. 

Many lipid-based foods show time-dependent rheological behavior and a combination of these, for example, viscous-elastic and viscous-plastic. In general, lipids, from a rheological point of view, can be classified as Newtonian and non-Newtonian, as depicted in Figure 4.1. To characterize lipid properties, such as Newtonian and non-Newtonian behavior, several approaches can be taken and the stress-strain relationships obtained. 

Fibers represent a special case, as such optical properties as refractive index and birefringence are important not so much for their influence on the appearance or performance of the product but as an aid to fiber identification. Fiber optical properties are considered in Chapter 19. Although similar identification techniques are applicable to transparent plastics in general, such tests are not widely used outside the forensic. science... 

Two Controversies around Plastic Materials and their Media Coverage 7 1.3.2. Plastics in general... 

Linear or branched, that is, not crosslinked, thermoplastic materials, usually first begin to soften on heating and then on further heating (amorphous polymers) begin to flow over a rather ill-defined temperature range (see Figure 3.1). Partially crystalline plastics in general have narrow melt-... 

In addition to the primary bonding forces at work in the molecular chain between C or Si or intercalary atoms (heteroatoms), the intermolecular bonding forces are important determinant factors in the properties of plastics. In general, only weak attractive forces due to molecular polarization are active between covalently bonded molecular chains. 

Because of the viscoelastic behavior of plastics in general, and plastic melts in particular, this relaxation of the molecular chains is dependent on the factors time and temperature and is entropy elastic. The longer the die, the more time the molecules have to relax within a fixed die cross-section, so that the swell factor after the material exits from the die will be reduced. 

As far as the production, consumption and management at the end of the service life of biodegradable plastics in general are concerned, from both petrochemical and... 

Here, elastoviscous is defined as rheological behavior with predominantly viscous and little elastic character, whereas viscoelastic is behavior with mainly elastic and little viscous character. Materials that behave elastoplastically show a marked flow limit. Naturally, all kinds of intermediate patterns of behavior are found between these two. Spinning into fibers can be considered a special case in the processing of plastics. In general, the processibility improves with increasing width of the molar mass distribution. 

While these contributions of plastics toward sustainability are seldom questioned, it was a common believe in the early nineties in Germany that this material could not be recycled. This provoked a critical public position toward plastics in general. 

Cellulose butyrate (also carbon black reinforcing pigment) Chlorinated butadiene rubber Conjugated diene butyl elastomer Cellulose plastics in general... 

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