Plastic properties, modification

The reasons that determine the properties modification by tear and fatigue can be the following 1) the appearance of free macroradicals under the deformation conditions 2) the activation of some reactions with medium components 3) chains reorientation and packing in supramolecular formations 4) the appearance of adsorption and superficial-active properties of the mechano-destruc-tion products and 5) the ordering and plastic properties modification of the contact surfaces by friction with the polymer [595]. 

Polystyrene. Polystyrene shows compatibiHty with common plasticizers but modification of properties produced is ofHtde value. Small amounts of plasticizer (eg, DBP) are used as a processing aid. 

K-Resin SB Copolymer/Crystal Polystyrene Sheet Property Modification with High Impact Polystyrene, Plastics Technical Center Report 409, Chevron Phillips Chemical Co., Bartlesville, OK. 

Skochdopole, R.E. and Rubens, L.C., "Physical Property Modifications of Low-Density Polyethylene Foams, Journal of Cellular Plastics, 1 91-96 (January 1965). 

In this investigation, the short-term behaviour of the protected waterproofing has been studied. It should be pointed out, however, that, due to the plastic properties of the recycled material, including migration of plasticizers, modificators, and so on, the long-term behaviour of the system is also of importance and requires due attention. 

Compounding technology and performance evaluation became more sophisticated. Formulators learned to measure a plasticizer s basic performance more accurately, evaluate its permanence more fully, and assess the commercial value of optimizing particular property modifications. Customers increasingly demanded end products with enduring integrity, through their own standards as well as to meet... 

A major property improvement achieved through plasticization is the enormous reduction in the glass transition temperature, T, of PVC so that pliability and impact resistance of the plasticized composition is retained over a wide temperature range. Lowering of T is so important in the free volume theory that it is considered by some synonymous with plasticization. Many essential commercial applications of flexible vinyl depend upon this property modification. Without low-temperature flexibility, some of the... 

The viscosity index of a plasticizer per se is a predictor of its low-temperature flexibility efficiency. A small viscosity change with change in temperature indicates it will confer flexibility at low temperatures better than a plasticizer that shows a greater change in viscosity with temperature change. All the performances rated above conform to this principle. The low-temperature performance of plasticizer mixtures can be closely predicted simply by interpolations based upon their individual performance and the concentration in which they will be used. Formulation techniques have been computerized by such guidance a wide range of property modifications can be achieved with mixtures and specified property values can be maintained with the indicated substitutions and concentrations (42). 

These assumptions are not always justifiable when applied to plastics unless modification has occurred. The classical equations cannot be used indiscriminately. Each case must be considered on its own merits, with account being taken of such factors as the mode of deformation, the service temperature and environment, the fabrication method, and so on. In particular, it should be noted that the past traditional equations that have been developed for other materials, principally steel, use the relationship that stress equals the modulus times strain, where the modulus is constant. Except for thermoset reinforced plastics and certain engineering plastics, many plastics do not generally have a constant modulus. Different approaches have been used for the nonconstant situation some are quite accurate. The drawback is that most of these methods are quite complex, involving numerical techniques that are not attractive to designers. One method that has been widely accepted is this so-called pseudoelastic design method. In this method appropriate values of such time-dependent properties as the modulus are selected and substituted into the standard equations. 

The volume is divided into three parts Part I. Metallization Techniques and Properties of Metal Deposits, Part II, Investigation of Interfacial Interactions," and Part III, "Plastic Surface Modification and Adhesion Aspects of Metallized Plastics. The topics covered include various metallization techniques for a variety of plastic substrates various properties of metal deposits metal diffusion during metallization of high-temperature polymers investigation of metal/polymer inlerfacial interactions using a variety of techniques, viz., ESCA, SIMS, HREELS, UV photoemission theoretical studies of metal/polymer interfaces computer simulation of dielectric relaxation at metal/insulalor interfaces surface modification of plastics by a host of techniques including wet chemical, plasma, ion bombardment and its influence on adhesion adhesion aspects of metallized plastics including the use of blister test to study dynamic fracture mechanism of thin metallized plastics. 

Table 3 Structural and property modification of the bacterial plastics... 

A variety of organic/inorganic additives, in either solid or liquid form, are incorporated into plastic articles to achieve desired surface property modification. Depending upon the specific function they perform in modifying the surface property, they could be categorized as follows ... 

Properties Modification Unmodified Rigid Plasticized, Non-Rigid... 

The good miscibility of PBI-PVPy blends can be useful for property modifications in the plastics industry, particularly in the areas of processability, where intermediate Tg values are sufficient and economical, and with retention of good mechanical properties at elevated temperatures. Blending can be achieved by solution mixing, and hydrogen bonding promotes compatibility. 

Film or sheet generally function as supports for other materials, as barriers or covers such as packaging, as insulation, or as materials of constmction. The uses depend on the unique combination of properties of the specific resins or plastic materials chosen. When multilayer films or sheets are made, the product properties can be varied to meet almost any need. Further modification of properties can be achieved by use of such additives or modifiers as plasticizers (qv), antistatic agents (qv), fire retardants, sHp agents, uv and thermal stabilizers, dyes (qv) or pigments (qv), and biodegradable activators. 

The property of polybutadiene of most interest to the mbber compounder is excellent abrasion resistance coupled with excellent resilience. The polymer has very high rebound and low heat generation. With a few exceptions, such as the core of soHd golf balls, the polymer is blended with other polymers to take advantage of its excellent abrasion and rebound. Uses in North America are as follows tires, 500,000 t (74%) plastic modification,... 

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