Plastics Specifications

In many process design applications like polymerization and plasticization, specific knowledge of the thermodynamics of polymer systems can be very useful. For example, non-ideal solution behavior strongly governs the diffusion phenomena observed for polymer melts and concentrated solutions. Hence, accurate modeling of... 

What this discussion identifies is that each material (specific plastic, specific steel, specific wood, etc.) behaves certain ways. If a product can be made from a specific steel rather than a specific plastic, that is the material to use. However, unfortunately for steel and other materials, plastics continue to expand its use where these other materials are not competitive propertywise and/or cost-wise. 

The Ml test equipment is easy to operate, provides repeatable results, and low cost to operate. It is widely used for quality control and for distinguishing between members of a single family of plastics. Specifically, this MI makes a single-point test that provides information on resistance to flow at only a single shear rate. Because variations in branching or MWD can alter the shape of the viscosity curve, the MI may give a false ranking of plastics in terms of their shear rate resistance to flow. To overcome this problem, extrusion rates are sometimes measured for two loads, or other modifications are made. 

Moulded plastic Specific mechanical property bearing inserts... Overmoulding, post-moulding insertion by means of pressure (and heat)... 

Table 15-2 Plastic specific parameter-values for Dpin polyolefins.

With the above set of plastic specific parameters for polyolefins, a Devalue can be calculated using Eq. (15-3) for each molecular mass up to about 4000 dalton and temperature Tm>T>Tg, where Tm is the melting temperature of the polymer. 

ISO 4898-84 Cellular Plastics - Specification for Rigid Cellular Materials Used in the Thermal Insulation of Buildings, 6 pp... 

It was first synthesized by Friedrich Wohler in 1828 by evaporating a solution of ammonium cyanate. Urea is found in small amounts in the blood of mammals. Its principal industrial usage is in the manufacture of plastics (specifically, urea-formaldehyde resin) and is also a component of many fertilisers, providing a nitrogen source for plants. 

The following data represent average properties of this plastic. Specific Gravity 1.37... 

There are several aspects of plastics specifications and drawings (or files) which are particular to this family of materials and processes and which deal with realities which must be addressed. The following sections will discuss them in detail. 

The use of plastics specifically in building construction is discussed in five sections in Chapter 3, by considering their structural, secondary structural and non-structural applications and also their use in polymeric coatings and EPDM membranes. Systems for condensation control is the theme of Chapter 4. 

Another segment for recyclate is the substitution of conventional construction materials such as hardwood, non-structural lumber, or concrete. It is precisely the plastics specific characteristics from which technological advantages can be derived, leading to a low system cost as long as a comparable lifetime can be achieved [251, 267, 268]. 

In order to perform quality control the quality requirements or parameters should be known. cGMP regulation demands that the characteristics of containers important for product quality are defined in specifications [5]. The Ph. Fur. describes general requirements for some packaging types and materials (glass, rubber and various plastics). Specifications for containers are more specific for individual... 

Table 5.4 Chemical analysis of additives in plastics specific spray reagents for location of compounds by thin-layer chromatography ...

As noted in Table 3 [77], the results of multiple alloy tests in seawater are correlated to the Pitting Resistance Equivalence (PRE) number [47,48,72,77], which also correlates to alloy pterformance in FeCly. Anderson [78] and Streicher [79] used MCA in seawater tests to compare alloy performance. More recently, a simple, flat, plastic (specifically, polymethylmethacrylate, which is often referred to as "perspex ) washer has been successfully used to evaluate a series of alloys in seawater [77]. One application of the ASTM G 48 test has been in simulating leaking tube-to-tube sheet joints in seawater heat exchangers and condensers [87]. When certain highly corrosion-resistant alloys were paired in a dissimilar metal crevice (DMC) with alloys that would be expected to suffer crevice corrosion in the particular test solution, the more corrosion-resistant alloy was found to corrode due to the accelerating effects of the corrosion products from the less resistant alloy. The results of DMC tests in ferric chloride were confirmed by long-term DMC exposures in seawater [82],... 

For this reason the correct selection of an HR system frequently demands an expanded plastic specification, particularly as each manufacturer employs his own compositions and types of additives, has his own designations and places greater emphasis on the advantages during application than on the difficulties and restrictions encountered during processing. 

Table 7.52 - Chemical Analysis of Additives in Plastics Specific Spray Reagents for Locations of Compounds by Thin-Layer Chromatography... 

Understanding how to process agro-polymers with similar properties to synthetic polymers requires an understanding of how these forces are manifested in proteins. The processability of proteins depends on their transition from the glassy to rubbery and viscous-flow states. These transitions are achieved with judicial application of heat, pressure, shear, chemical additives and plasticizers. Specific amino acid residues (primary protein structure) and initial structure (natural protein state) of the protein will influence each of these factors. Based on the structure of proteins and the requirement for thermoplastic processing, three broadly categorized processing requirements have been identified ... 

Some plastics can be completely amorphous or crystalline. Often plastics specifications will report what percent of it is crystalline, such as 73% crystallinity. Generally, polymer chains with bulky side groups cannot form crystalline regions. The degree of crystallinity depends on both the polymer and the processing technique. Some polymers such as PE crystallize quickly and reach high levels of crystallinity. Others, such as PET polyester, require slow cooling to crystallize. If cooled quickly, PET polyester remains amorphous in the final product. 

Tensile drawing of the wet polyacetylene films yielded a maximum stretching ratio of about 15 for the thick films and about 10 for thin films. By contrast, fully dried polyacetylene films could not be extended beyond 6 times their original length under otherwise similar experimental conditions. Some variation in the maximum stretching ratio, Xmax. was found, dependent on the characteristics of the liquid used as "plasticizer . Specifically, it was observed that Xmax was dependent on the boiling point and the specific composition in the case of mixed liquids. The results seem to indicate that Xmax is dependent on the relative content of solvent in the film and on the speed of evaporation of the solvent from bulk of the film. Hexadienes, for example, were found to be excellent plasticizers for polyacetylene, presumably due to the easier penetration of these liquids into the polyacetylene lattice because of the similarity in molecular structures. Pure aromatic solvents appeared to be the least effective however, a 4 1 mixture of toluene and cumene yielded excellent results. 

In addition to ASTM, several other groups, such as the National Electrical Manufacturers Association (NEMA), the Underwriters Laboratories (UL), the Institute of Electrical and Electronics Engineers (IEEE), and several US. government agencies issue plastics specifications, as do German (VDE and DIN) and British (BSD agencies. International standards are coordinated and written by the International Electrotechnical Commission (lEC). Despite such extensive and useful standardization activity, relatively little emphasis has been placed on the... 

Polyester polymeric plasticizers (or just simply polymeric plasticizers) are considered permanent plasticizers, and are used to compound vinyl requiring better performance than can be provided by monomeric plasticizers. Specifically, polymeric plasticizers are ... 

During the cooling of the component, the heat is drawn from it by the mould. The amount of heat involved depends on the component weight, the type of plastic (specific heat content), the ejection temperature, and the cycle frequency. The mould passes this heat to the environment (by heat conduction to the machine and by radiation or convection to the ambient air), if no special temperature control system is connected up. The higher the mould temperature, the greater the amount of heat released to the environment. So, when the machine starts up, the mould initially heats up to the temperature at which the amount of heat supplied by the solidifying and cooling plastic can be released to the environment. 

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