Polymer materials development trends

For some applications, a combination of materials may be required to achieve a composite with the desired properties and performance. Property-improved lignocellulosic fibers can be combined with materials such as metal, glass, plastic, natural polymers, and synthetic fiber to yield a new generation of composite materials. New composites will be developed that utilize the unique properties obtainable by combining many different materials. This trend will increase significantly in the future. 

In this special volume on polymer particles, recent trends and developments in the synthesis of nano- to micron-sized polymer particles by radical polymerization of vinyl monomers in environmentally friendly heterogeneous aqueous and supercritical carbon dioxide fluid media are reviewed by prominent worldwide researchers. Polymer particles are prepared extensively as synthetic emulsions and latexes, which are applied as binders in the industrial fields of paint, paper and inks, and films such as adhesives and coating materials. Considerable attention has recently been directed towards aqueous dispersed systems due to the increased awareness of environmental issues. Moreover, such polymer particles have already been applied to more advanced fields such as bio-, information, and electronic technologies. In addition to the obvious commercial importance of these techniques, it is of fundamental scientific interest to completely elucidate the mechanistic details of macromolecule synthesis in the microreactors that the polymer particles in these heterogeneous systems constitute. 

Whatever the outcome will be between these emerging trends, it is a fact that modelling is making an ever stronger contribution to our understanding of the complex behaviour of polymers, and is changing the way in which new polymer materials are developed. 

The chapters in this volume represent the current trends in the fields of polymer blends and ionomers, including materials development, characterization, theory, and processing. They are grouped into six sections the first three are concerned with polymer blends and interpenetrating networks and the latter three with ionomers. 

This chapter will first discuss fracture mechanics applications to polymer composites in aerospace, and then compile the different test methods by type of load. The industiy-specific fracture mechanics test procedures for FRP composites, such as the Airbus Industries Test Method (AITM) or Boeing Support Specification (BSS), are essentially based on test procedures developed by national or international standardization agencies. This will be followed by a section with literature data to highlight selected effects of processing and material layup and type. Further sections will discuss non-unidirectional reinforcement and testing under environmental conditions that are relevant to aerospace applications, and the chapter concludes with an outlook on materials and test development trends. 

On the other hand, with the rapid development of the polymer material industry, the application areas of polymeric materials are also expanding. Some novel requirements for the properties of polymer materials have been proposed. The performance of a single polymer material is difficult to meet the needs of practical application. Thus, the development and application of new materials, complementary properties between different materials, and composite modification will become the emerging trend in the development of new polymer materials. 

Due to its very unique and high thermal stability characteristics, PBI blends were studied and developed early on for aerospace and composite materials. The discovery of new polymeric alloys by blending commercially available polymers was the trend in materials development. A key reason for growth in this area was the ability to tailor existing materials to a new/unique set of property-performance-price specifications through combinations of materials. For example, a miscible blend based on PBI and polyimide (PI) was discovered and, after thorough investigations, PBI was found not only to have superior thermal/chemical properties, but to also... 

There have been numerous reports of possible allergic reactions to mercury and mercury salts and to the mercury, silver and copper in dental amalgam as well as to amalgam corrosion products Studies of the release of mercury by amalgams into distilled water, saline and artificial saliva tend to be conflicting and contradictory but, overall, the data indicate that mercury release drops with time due to film formation and is less than the acceptable daily intake for mercury in food . Further, while metallic mercury can sensitise, sensitisation of patients to mercury by dental amalgam appears to be a rare occurrence. Nevertheless, there is a growing trend to develop polymer-based posterior restorative materials in order to eliminate the use of mercury in dentistry. 

In preceding chapters we have indicated which tools are nowadays being used routinely or currently are under development. General trends are higher sensitivity, more information, and faster and further automation. Automatic analyses are nice (sample in, report out), but interactive analysis tools are better. It is not realistic to expect the need for more analyses. Some future needs are more reliable quantitation, reference materials and simplification of data management. A particular problem in additive analysis concerns accuracy and traceability. In many cases, extractable rather than total concentration is determined. There are still many quantitative analytical methods waiting to be developed. It is here that the field will advance. Table 10.31 lists some proposed (r)evolutionary developments in polymer/additive analysis. 

---