Search Results for polymer structure

This article describes in more detail the fundamental building-block level, atomic, then expands to a discussion of molecular considerations, intermolecular structures, and finally supermolecular issues. An explanation of important thermal, mechanical, and physical properties of engineering plastics and commodity plastics follows, and the final section briefly outlines the most common plastics manufacturing processes.

This introductory article describes the various aspects of chemical structure and composition that are important to an understanding of polymer properties and their eventual effect on the end-use performance of engineering plastics, namely thermoplastics and thermosets. The most important properties of polymers and the most significant influences of structure on those properties are covered. The article also includes some general information on the classification and naming of polymers and plastics.

This article discusses the chemical susceptibility of a polymeric material. The discussion covers significant absorption and transportation of an environmental reagent by the polymer; the chemical susceptibility of additives; and thermal degradation, thermal oxidative degradation, photo-oxidative degradation, environmental corrosion, and chemical corrosion of polymers. It also includes some of the techniques used to detect changes in structure during polymer exposure to hostile environments. In addition, the article describes the effects of environment on polymer performance, namely plasticization, solvation, swelling, environmental stress cracking, polymer degradation, surface embrittlement, and temperature effects.

This chapter explains the distinction between materials and matter through the concept of microstructure. It presents the history of matter science and the establishment of metallography. The chapter provides an overview of the progress of steel technology, progress in synthetic polymers and ceramics, and establishment and development of materials science.

This article introduces procedures an engineer or materials scientist can use to investigate failures. It provides a brief survey of polymer systems and key properties that need to be measured during failure analysis. The article begins with an overview of the problem-solving approach pertinent to structure analysis. This is followed by a review of the characterization of plastics by infrared and nuclear magnetic resonance spectroscopy. The article then provides information on the distribution of molecular weight of an engineering plastic. It further discusses the methods used in thermal analysis, namely differential thermal analysis, thermogravimetric analysis, thermal-mechanical analysis, and dynamic mechanical analysis. The following sections provide details on X-ray diffraction for analyzing crystalline phases and on a minimal scheme for polymer analysis and characterization to assist the design engineer. The article ends with a discussion on the thermal-analytical scheme for analyzing the milligram quantities of polymer samples.

This chapter discusses the use of thermoset and thermoplastic resins in polymer matrix composites. It begins by explaining how the two classes of polymer differ and how it impacts their use as matrix materials. It then goes on to describe the characteristics of polyester, vinyl ester, epoxy, bismaleimide, cyanate ester, polyimide, and phenolic resins and various toughening methods. The chapter also covers thermoplastic matrix materials and product forms and provides an introduction to the physiochemical tests used to characterize resins and cured laminates.

To ensure the proper application of plastics, one must keep in mind three factors that determine the appropriate end-use: material selection, processing, and design. This article begins by providing information on various factors pertinent to the anticipated use conditions of the article to be designed. This is followed by a discussion on several stages necessary to define the geometry of plastic parts. Details on the strength of and cost estimation for plastic parts are then provided. The article ends with a section providing information on the structure, properties, processing, and end-use applications of plastics.

This chapter covers the fatigue and fracture behaviors of ceramics and polymers. It discusses the benefits of transformation toughening, the use of ceramic-matrix composites, fracture mechanisms, and the relationship between fatigue and subcritical crack growth. In regard to polymers, it covers general characteristics, viscoelastic properties, and static strength. It also discusses fatigue life, impact strength, fracture toughness, and stress-rupture behaviors as well as environmental effects such as plasticization, solvation, swelling, stress cracking, degradation, and surface embrittlement.

This chapter discusses the effect of fatigue on polymers, ceramics, composites, and bone. It begins with a general comparison of polymers and metals, noting important differences in microstructure and cyclic loading response. It then presents the results of several studies that shed light on the fatigue behavior and crack growth mechanisms of common structural polymers and moves on from there to discuss the fatigue behavior of bone and how it compares to stable and cyclically softening metals. It also discusses the fatigue characteristics of engineered and composited ceramics and ceramic fiber-reinforced metal-matrix composites.