Search Results for plastic film

This article describes the process and advantages of no-bond methods of vacuum molding and magnetic molding, with schematic illustrations. It also discusses the characteristics of plastic film and dimensional specifications of vacuum molding.

This article describes the extrusion process, which converts soft, plastic material into a particular form using an extruder, or screw conveyer. It discusses the two main types of plastic extruders, twin-screw and single-screw, estimation of extruder capacity, and design and operations (heating, cooling, downstream sizing, corrugating, and crossheading) of the screw, the most important component of any extruder. It discusses the shapes produced by screw extrusion and the types of extrusion products produced by extrusion processes, including blown-film extrusion, flat-film or sheet extrusion, chill-roll film extrusion, pipe or tube extrusion, wire and cable coverings, extrusion coating, and profile extrusion, and provides some discussion on multiple-screw extruders. The article describes the dimensional accuracy of extrusion products, and lists common defects that occur frequently in the extrusion process.

This article describes the numerous techniques used to measure friction. It provides a brief description of the historical development of friction testing. The article discusses the tests and equipment available for friction testing. It explains the procedural considerations that should be addressed to ensure that valid data are derived from a friction test. The article presents definitions of terms commonly used in tribology such as static friction, kinetic coefficient of friction, stick-slip behavior, and lubricated friction. It provides information on the precautions that must be taken to ensure valid test results. The article also describes how to report data and how to analyze these data.

Tribology is the science and technology of interacting surfaces in relative motion or, the study of friction, wear, and lubrication. This article focuses on friction and wear processes that aid in the evaluation and selection of materials, for polymers and some composites used in friction and wear applications. It provides information on friction, types of wear, and lubrication. The article includes a brief description of the friction and wear test methods, laboratory-scale friction, and wear testing, usually performed either to rank the performance of candidate materials for an application or to investigate a particular wear process. It describes the wear tests conducted with/without abrasives and explains the concept of PV limit (where P is contact pressure and V is velocity). The article concludes with references and tables of friction and wear test data for polymeric materials.

Electrochemical discharge grinding (ECDG) is a combination of electrochemical grinding (ECG) and electrical discharge grinding (EDG), with some modification of each. This article commences with a schematic illustration of a setup for ECDG using a solid bonded graphite wheel. It describes the process characteristics of ECDG in terms of current density, wheel speed, wear ratio, accuracy and finish, wheel maintenance, and profile grinding. The article concludes with a comparison of ECDG with EDG and ECG.

This article provides an overview of plasma surface treatments for plastics. It covers the equipment and methods used in plasma processing, providing detailed explanations of the plasma discharge reactions and how they affect surface state and topography. It also provides information on contamination removal, plasma surface modification, plasma-induced grafting, and plasma film deposition.

The application of transmission electron microscope to the study of fracture surfaces and related phenomena has made it possible to obtain magnifications and depths of field much greater than those possible with light (optical) microscopes. This article reviews the methods for preparing single-stage, double-stage, and extraction replicas of fracture surfaces. It discusses the types of artifacts and their effects on these replicas, and provides information on shadowing of replicas. The article concludes with a comparison of the transmission electron and scanning electron fractographs with illustrations.

The process of coating plastics with metals for functional purposes is called metallizing of plastics. This article discusses the metallizing of plastics, provides information on its history, and gives a short note on applications and adhesion properties of metallic coatings. It also discusses the selection of plastics for plating. This article also describes metallizing techniques, including plating (electrolytic or electroplating), vacuum metallizing and thermal spraying, and environmental considerations. The article discusses the quality assurance procedures for metallized plastic parts which include tests that assess the quality of the finish, coating thickness, adhesion, and corrosion resistance, and gives a short note on service performance, which includes service condition classifications.

The introduction of focused ion beam (FIB) microscopy in the 1990s added the capability of studying fracture surfaces in the third dimension and making site-specific and stress-free transmission electron microscope (TEM) specimens in situ. This article reviews the methods for preparing replicas and the site-specific FIB thin-foil preparation technique. It provides an overview of FIB-TEM specimen preparation.

This article describes the techniques for measuring friction, namely, inclined-plane method; friction test methods using weights and pulleys; friction tests of shafts and capstans; other types of friction tests, including standards; microscale friction tests; and friction testing under well-lubricated conditions. The procedural considerations that should be addressed to ensure that valid data are derived from a friction test are discussed. The article explains friction testing geometries, the major considerations implicit in their use as well as friction test parameters, such as speed and load. It also demonstrates how to report friction data and how these data can be entered into a database.

This article describes the features, benefits and limitations of petrolatum and microcrystalline wax. It provides a detailed discussion on the steps to be followed before applying the various forms of the wax-based coatings. The wax-based coating forms include petrolatum and microcrystalline tapes, marine petrolatum-based pile systems; cold-applied petrolatum-based paste coating systems; hot-applied microcrystalline wax flood coating systems; wax-based dips, brushons, and sprays; and wax-impregnated fabrics and wax-coated papers. The article also discusses the applications and limitations of these wax-based coatings. It concludes by highlighting the steps involved in the installation of wax-based casing fillers.

This article discusses the most fundamental building-block level, atomic level, molecular considerations, intermolecular structures, and supermolecular issues. It contains a table that shows the structures and lists the properties of selected commodity and engineering plastics. The article describes the effects of structure on thermal and mechanical properties. It reviews the chemical, optical, and electrical properties of engineering plastics and commodity plastics. An explanation of important physical properties, many of which are unique to polymers, is also included. The factors that must be considered when processing engineering thermoplastics are discussed. These include melt viscosity and melt strength; crystallization; orientation, die swell, shrinkage, and molded-in stress; polymer degradation; and polymer blends.

There are many different types of polymeric materials, ranging from glassy to semicrystalline polymers and even blends. Their mechanical properties range from pure elastic with very high strains to fracture (elastomers) to almost pure linear elastic (Hookian behavior) with low strains to fracture (glassy polymers). This article provides an overview of historical development of fracture behavior in polymers. It discusses the processes involved in three fracture test methods for polymers, namely linear elastic fracture mechanics, elastic-plastic fracture mechanics, and post-yield fracture mechanics.

This article focuses on the evaluation of mechanical properties of freestanding films and films adherent to their substrates. Common methods of testing freestanding films, including uniaxial tensile testing, uniaxial creep testing, biaxial testing, and beam-bending methods, are discussed. For films which are adherent to their substrates, indentation testing is used to evaluate hardness, creep, and strength.

In terms of their electrical properties, plastics can be divided into thermosetting and thermoplastic materials, some of which are conductive or semiconductive. This article provides detailed information on factors that affect the property of plastics. It discusses the major test methods used to determine the following dielectric properties of plastics: dielectric breakdown voltage, dielectric strength, dielectric constant, dissipation factor, arc tracking resistance, insulation resistance, volume, and surface resistivity or conductivity. The test specifications and conditions, recommended by several U.S. and foreign testing organizations for characterizing the electrical properties of plastic materials are listed. The article describes the influence of these properties on selection of plastics for insulation application. An outline of the electromagnetic shielding and testing methods of electromagnetic interference are also provided. Designations, electrical properties, and applications of elastomers are tabulated.

This article addresses electrical testing and characterization of plastics and presents a number of techniques for evaluating the electrical properties of insulating materials, with a special focus on plastics, accompanied by a list of the electrical properties of different types of plastics. It provides the reader with sufficient information to select the appropriate electrical test(s) for a specific application. The tests covered in this article are widely used in industry to determine the electrical properties of insulating materials, particularly plastics. The article lists and defines terms used in connection with testing and specification of plastics for electrical applications.

This article describes measurement techniques for the three basic types of adhesion: fundamental adhesion, thermodynamic adhesion, and practical adhesion. It discusses common measurement methods for each type of adhesion with the main focus on practical adhesion testing of coatings and thin films. The article provides an insight into the mechanisms of environmentally induced interfacial degradation by discussing the fundamental aspects of adhesion between two dissimilar materials. It examines the use of adhesion tests in the evaluation of stress-corrosion cracking within bimaterial interfaces. Testing techniques for <i>in situ</i> environmental testing of thin-film adhesion are also reviewed.