This chapter discusses thermoplastic composite fabrication processes and related equipment and procedures. The discussion covers consolidation and thermoforming operations as well as joining methods.

This article addresses some established protocols in characterizing thermoplastics, whether they are homogeneous resins, alloyed or blended compositions, or highly modified thermoplastic composites. It begins with a description of various approaches used for the determination of molecular weight (MW) by viscosity measurements. This is followed by a discussion of the use of cone and plate and parallel plate geometries in determining the viscoelastic properties of a polymer melt. Details on some of the chromatographic techniques that allow determination of MW and MW distribution of polymers are then provided. The article concludes with information on three distinctive, but complementary operations of thermoanalytical techniques, namely differential scanning calorimetry, thermogravimetric analysis, and thermomechanical testing.

This chapter reviews materials issues encountered in joining, including challenges involved in welding of dissimilar metal combinations; joining of plastics by mechanical fastening, solvent and adhesive bonding, and welding; joining of thermoset and thermoplastic composite materials by mechanical fastening, adhesive bonding, and, for thermoplastic composites, welding; the making of glass-to-metal seals; and joining of oxide and nonoxide ceramics to themselves and to metals by solid-state processes and by brazing. The classification, types, applications, and the mechanism of each of these methods are covered. The factors influencing joint integrity and the main considerations in welding dissimilar metal combinations are also discussed.

This article depicts typical fractographic features for a number of different composite materials, covering interlaminar and translaminar fracture characteristics in composite materials.

Polymer-matrix composites are among the lightest structural materials in use today. They are also highly resistant to corrosion and fatigue and their load-carrying capabilities, such as strength and stiffness, can be tailored for specific applications. This chapter discusses the primary advantages and disadvantages of polymer-matrix composites, how they are produced, and how they perform in different applications. It describes the construction of laminates, the fibers and resins used, and the methods by which they are combined. It explains how strength, modulus, toughness, and high-temperature and corrosion behaviors are determined by the orientation, shape, and spacing of fibers, the number of plies, resin properties, and consolidation and forming methods. The chapter also covers secondary fabrication processes, such as thermoforming, machining, and joining, as well as production equipment and product forms, and include guidelines for optimizing tradeoffs when selecting fibers, resins, and production techniques.

This chapter discusses the effect of fiber length and orientation on the strength and stiffness of discontinuous-fiber composites. It also describes several fabrication processes, including spray-up, compression molding, reaction injection molding, and injection molding.

This chapter provides an overview of the tools and techniques, as well as some of the underlying theory, that have proven useful for process modeling and simulation. It begins by presenting the framework of a thermoset cure model that accounts for kinetics, viscosity, heat transfer, flow, voids, and residual stress. It then discusses each variable in detail, explaining how it affects the cure process, how it is measured, and how it can be expressed mathematically in the form of a simple model. The discussions throughout the chapter are supported by numerous images, diagrams, and data plots.

This chapter discusses the failure mechanisms associated with fiber-reinforced composites. It begins with a review of fiber-matrix systems and the stress-strain response of unidirectional lamina and both notched and unnotched composite laminate specimens. It then explains how cyclic loading can lead to delamination, the primary failure mode of most composites, and describes some of the methods that have been developed to improve delamination resistance, assess damage tolerance, determine residual strength, and predict failure modes.

Unlike metals, in which fatigue failures are due to a single crack that grows to a critical length, the effects of fatigue in composites are much more distributed and varied. As the chapter explains, there are five major damage mechanisms that contribute to the progression of composite fatigue, those being matrix cracking, fiber breaking, crack coupling, delamination initiation, and delamination growth. The chapter describes each mechanism in detail along with related factors. It also discusses the primary differences between composites and metals, the effect of manufacturing defects, damage tolerance, and testing and certification.

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.

This chapter describes the molecular structures and chemical reactions associated with the production of thermoset and thermoplastic components. It compares and contrasts the mechanical properties of engineering plastics with those of metals, and explains how fillers and reinforcements affect impact and tensile strength, shrinkage, thermal expansion, and thermal conductivity. It examines the relationship between tensile modulus and temperature, provides thermal property data for selected plastics, and discusses the effect of chemical exposure, operating temperature, and residual stress. The chapter also includes a section on the uses of thermoplastic and thermosetting resins and provides information on fabrication processes and fastening and joining methods.

This article provides details on several of the classifications of polymer wear mechanisms, using wear data and micrographs from published works. The primary goals are to present the mechanisms of polymer wear and to quantify wear in terms of wear rate. The discussion begins by providing information on the processes involved in interfacial and cohesive wear. This is followed by sections describing the wear process and applications of elastomers, thermosets, glassy thermoplastics, and semicrystalline thermoplastics. The effects of environmental and lubricant on the wear failures of polymers are then discussed. The article further includes a case study describing the tribological performance of nylon. It ends by presenting some examples of wear failures of plastics.

This article describes the mechanisms of moisture-induced damage in polymeric materials, covering the characteristics of important structural plastics; the effects of moisture on glass transition temperature, modulus, creep, and stress relaxation of plastic materials; and moisture-induced fatigue failure in composites. The effect of moisture on the mechanical properties of thermoset resins and thermoplastics are also discussed.

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 covers the thermal analysis and thermal properties of engineering plastics with respect to chemical composition, chain configuration, and/or conformation of the base polymers. The thermal analysis techniques covered are differential scanning calorimetry, thermogravimetric analysis, thermomechanical analysis, and rheological analysis. The basic thermal properties covered include thermal conductivity, temperature resistance, thermal expansion, specific heat, and the determination of glass-transition temperatures. The article further describes various factors influencing the determination of service temperature of a material. Representative examples of different types of engineering thermoplastics are discussed in terms of structure and thermal properties. The article also discusses the thermal and related properties of thermoset resin systems.

This article discusses various factors influencing general polymeric behavior, ductile-brittle transitions, crazing, and the brittle fracture of polymeric materials. The discussion covers the effects of environment on glassy thermoplastic, several parametric descriptions of craze initiation, the kinetics of craze growth, and the effect of crazing on toughness of the plastic. In addition, the article provides information on various tests to determine stress-to-craze value, strain-to-craze value, and fracture toughness of the plastic.

This chapter examines the static, fatigue, and damage tolerance properties of glass, aramid, and carbon fiber systems. It also explains how delaminations, voids, porosity, fiber distortion, and fastener hole defects affect impact resistance and strength.

This chapter covers the basic aspects of composite materials. It describes the arrangement, form, and function of their constituent materials and explains how they perform better in combination than on their own. It discusses the directional nature of isotropic, anisotropic, and orthotropic materials, the orientation of plies in unidirectional (lamina) and quasi-isotropic (laminate) lay-ups, and the dominant role of fibers in determining strength, stiffness, and other lamina properties. The chapter also compares the engineering attributes of composites with those of metals and includes application examples.

This chapter familiarizes readers with the many and varied thermoset composite fabrication processes and the types of applications for which they were developed. It describes wet lay-up, prepreg lay-up, and low-temperature vacuum bag curing prepreg processes, which are best suited for low-volume, medium-sized and larger parts. It also discusses filament winding and preforming processes (including weaving, knitting, stitching, and braiding) in addition to resin-transfer molding, resin film infusion, and pultrusion.

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.