Search Results for reinforced polymers

This article reviews the abrasive and adhesive wear failure of several types of reinforced polymers, including particulate-reinforced polymers, short-fiber reinforced polymers (SFRP), continuous unidirectional fiber reinforced polymers (FRP), particulate-filled composites, mixed composites (SFRP and particulate-filled), unidirectional FRP composites, and fabric reinforced composites. Friction and wear performance of the composites, correlation of performance with various materials properties, and studies on wear-of failure mechanisms by scanning electron microscopy are discussed for each of these types.

Reinforced polymers (RPs) are widely used in structural, industrial, automotive, and engineering applications due to their ecofriendly nature and the potential to manipulate their properties. This article addresses the technical synthesis of RPs, referring to their tribological behavior, to provide insights into the contribution and interaction of influential parameters on the wear behavior of polymers. It provides a brief discussion on the effects of significant parameters on RP tribology. The article describes abrasive and adhesive wear and provides a theoretical synthesis of the literature regarding the wear mechanisms of RPs. It also describes the synthesis of abrasive wear failure of different types of RPs and highlights the contribution of these influential parameters. The article addresses the synthesis of adhesive wear failure of different types of RPs.

This article is a compilation of abbreviations of terms, techniques, standards, compounds, and properties of materials that are relevant to the characterization and failure analysis of plastics.

Failure of structural polymeric materials under cyclic application of stress or strain is a subject of industrial importance. The understanding of fatigue mechanisms (damage) and the development of constitutive equations for damage evolution, leading to crack initiation and propagation as a function of loading or displacement history, represent a fundamental problem for scientists and engineers. This article describes the approaches to predict fatigue life and discusses the difference between thermal and mechanical fatigue failure of polymers.

Of the many different nondestructive evaluation (NDE) techniques, ultrasonic inspection continues to be the leading nondestructive method for inspecting composite materials, because measurements can be quantitative and the typical defect geometries and orientations lend themselves to detection and characterization. This article focuses on the three common methods for ultrasonic nondestructive inspection of plastics, namely pitch-catch, through-transmission, and pulse-echo, as well as the three basic types of ultrasonic NDE scans: the A-scan, B-scan, and C-scan. The discussion includes the linear and phased array systems that are sometimes used for large-scale inspection tasks to reduce scan times, the various gating and image processing techniques, and how ultrasonic data are interpreted and presented. A brief section on future trends in ultrasonic inspection is presented at the end of the article.

This article provides an overview of the physics and math associated with moisture-related failures in plastic components. It develops key equations, showing how they are used to analyze the causes and effects of water uptake, diffusion, and moisture concentration in polymeric materials and resins. It explains how absorbed moisture affects a wide range of properties, including glass transition temperature, flexural and shear modulus,creep, stress relaxation, swelling, tensile and yield strength, and fatigue cracking. It provides relevant data on common polymers, resins, and fiber-resin composites.

Accelerated life testing and aging methodologies are increasingly being used to generate engineering data for determining material property degradation and service life (or fitness for purpose) of plastic materials for hostile service conditions. This article presents an overview of accelerated life testing and aging of unreinforced and fiber-reinforced plastic materials for assessing long-term material properties and life expectancy in hostile service environments. It considers various environmental factors, such as temperature, humidity, pressure, weathering, liquid chemicals (i.e., alkalis and acids), ionizing radiation, and biological degradation, along with the combined effects of mechanical stress, temperature, and moisture (including environmental stress corrosion). The article also includes information on the use of accelerated testing for predicting material property degradation and long-term performance.

This introductory article describes the various aspects of chemical structure that are important to an understanding of polymer properties and thus their eventual effect on the end-use performance of engineering plastics. The polymers covered include hydrocarbon polymers, carbon-chain polymers, heterochain polymers, and polymers containing aromatic rings. The article also includes some general information on the classification and naming of polymers and plastics. The most important properties of polymers, namely, thermal, mechanical, chemical, electrical, and optical properties, and the most significant influences of structure on those properties are then discussed. A variety of engineering thermoplastics, including some that are regarded as high-performance thermoplastics, are covered in this article. In addition, a few examples of commodity thermoplastics and biodegradable thermoplastics are presented for comparison. Finally, the properties and applications of six common thermosets are briefly considered.

Manufacturing process selection is a critical step in plastic product design. The article provides an overview of the functional requirements that a part must fulfil before process selection is attempted. A brief discussion on the effects of individual thermoplastic and thermosetting processes on plastic parts and the material properties is presented. The article presents process effects on molecular orientation. It also illustrates the thinking that goes into the selection of processes for size, shape, and design factors. Finally, the article describes how various processes handle reinforcement.

There are many reasons why plastic materials should not be considered for an application. It is the responsibility of the design/materials engineer to recognize when the expected demands are outside of what the plastic can provide during the expected life-time of the product. This article reviews the numerous considerations that are equally important to help ensure that part failure does not occur. It provides a quick review of thermoplastic and thermoset plastics. The article focuses primarily on thermoset materials that at room temperature are below their glass transition temperature. It describes the motivation for material selection and the goal of the material selection process. The use of material datasheets for material selection as well as the processes involved in plastic material selection and post material selection is also covered.

This article focuses on manufacturing-related failures of injection-molded plastic parts, although the concepts apply to all plastic manufacturing processes It provides detailed examples of failures due to improper material handling, drying, mixing of additives, and molecular packing and orientation. It also presents examples of failures stemming from material degradation improper use of metal inserts, weak weld lines, insufficient curing of thermosets, and inadequate mixing and impregnation in the case of thermoset composites.