Physical properties, of plastics

Steps 1 and 2 can be described as physical plasticization, and the precise details of how this is carried out depends on the appHcations technology involved, ie, suspension or paste PVC. The rate at which step 2 occurs depends on the physical properties of plasticizer visocity, resin porosity, and particle size. 

Zinc dust is used in the sherardizing process where work pieces are tumbled with zinc dust in rotating steel dmms which are heated electrically or by gas to 370—420°C (149). The steel parts are uniformly coated with zinc. In the chemical and metallurgical industries, zinc dust is used as a reducing agent, in the manufacture of hydrosulfite compounds for the textile and paper industries, and to enhance the physical properties of plastics and lubricants (2). 

The carbon blacks used in plastics are usually different from the carbon blacks used in mbber. The effect of carbon black is detrimental to the physical properties of plastics such as impact strength and melt flow. Electroconductive grades of carbon black have much higher surface areas than conventional carbon blacks. The higher surface areas result in a three-dimensional conductive pathway through the polymer at much lower additive levels of the carbon black. The additive concentrations of electroconductive carbon blacks is usually j to that of a regular carbon black (132). 

Table 7-14 Example of mechanical and physical properties of plastics after sterilization... 

Thermal and physical properties of plastics (typical values) LDPE HDPE UHMWPE 50% glass-filled HDPE... 

Over the years efforts have been made to understand the various parameters to consider in the choice of plastics for packaging of drug products. Drug-plastic considerations have been divided into live separate categories permeation, leaching, sorption, chemical reaction, and alteration in the physical properties of plastics or products [89]. 

It is well known that thermoplastics as PVC will deteriorate easily by heating and oxidization. We tried to improve the physical properties of plastics by adding some commercial chemicals as stabilizer. 

The physical properties of plastic/polymer matrices and additives samples combined with the high GC column temperatures result in the mass spectrometer ion source becoming dirty more quickly than with typical usage. 

As can be imagined the radiation produced crosslinks and chain scissions act in opposite directions with respect to changing the physical properties of plastics. Crosslinks transform molten polyethylene from a liquid into an elastomer. The elastomeric properties thus produced make possible the so-called "memory effect" in which the irradiated PE, for example, when stretched at temperatures above its melting point and then cooled... 

Mungara, E T. Chang J. Zhu J.L. Jane. Processing and physical properties of plastics made from soy protein polyester blends./. Polym. Environ. 2002, 10, 31—37. 

Foster Sproxton was both director and chief chemist at British Xylonite. See for example his The rise of the plastics industry, Chemistry and Industry, 57 (25 June 1938), 607-616. Research into physical properties of plastics at the same firm was headed by W.G. Wearmouth, author of Physics and the plastics industry, Chemistry and Industry, 57 (17 December 1938), 1176-1182. The studies of Wearmouth and de Bruyne represented the high levels of understanding in industry of the physics underlying the behaviour of plastic materials. Many industrial chemists in the plastics industry demonstrated considerable mastery, through their trade and other publications, of the basic principles behind the processes of polymerization. 

Chapter 3 describes the various components of plastics and how they are transformed into three-dimensional functional solids. The chapter is not intended as a technical manual from which polymers can be synthesized and plastics prepared but as an overview of selected procedures and materials relevant to museum professionals concerned with plastics. Knowledge of plastics technology helps to date plastics objects, to interpret chemical analysis of plastics and to understand the causes of deterioration. Polymerization, additives and shaping processes contribute to the physical and chemical properties, useful lifetime and degradation pathways of plastics. The optical, chemical and physical properties of plastics are detailed in Chapter 4. 

Table 37-01. Physical Properties of Plasticized DuPont Elvanol 71-30 Film...

Whereas the physical properties of plastics are determined mainly by their morphological structure, their chemical behavior depends mainly on the chemical structure of their macromolecules. Thermoplastics are in most cases resistant to... 

INFLUENCE OF COMPATIBILITY ON MECHANICAL AND PHYSICAL PROPERTIES OF PLASTICIZED POLYMER... 

Higher melting point plastics such as PET become a filler if used in plastic lumber production. The physical properties of plastic lumber have been shown to improve significantly with the addition of PS to mixtures. 

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