Thermosets recent advances

With recent advances in the mixing of different types of thermosets and/or thermoplastics, the technology of IPN has provided very unique properties and performance. IPN is a method to produce very special network polymer blends. Two materials which do not react with each other are blended and subsequently cured in place. The blended network polymers... 

Nguyen MN, Chien lY, Koll PM. Recent Advancements in Olefin Thermoset Adhesive. Proc 50th Electronics Components and Tech. Conf. 2000 878-881. 

Unlike thermoplastics, thermosets react chemically to form cross-links, as described earlier, which limit chain movement. This network of polymer chains tends to degrade, rather than soften, when exposed to excessive heat. Until recently, thermosets could not be remelted and reused after initial curing. Recent advances in recycling have provided new methods for remelting and reusing thermoset materials. 

Polymers reinforced with cellulose fibers have received much attention in recent years because of their low density, nonabrasive, combustible, nontoxic, low cost and biodegradable properties. Several authors have reviewed recent advances in the use of natural fibers in composites like flax [ 1 ], jute [2,3], straw [4], kenaf [5,6], coir [7-9], fique [10], among others. Natural fibers have been used to reinforce thermoplastics and thermosets polymers in automotive and aerospace applications [11]. The influence of surface treatments of natural fibers on interfadal characteristics was also studied [12-17], and Joshi et al. [18] compared the life-cycle environmental performance of natural fiber composites with glass fiber composites. In this study, natural fiber composites were found to be environmentally superior in most applications. 

This entry examines several recent advances in pyrolysis gas chromatography-mass spectrometry (Py-GC/MS). The use of anal3dical pyrolysis coupled to GC/MS in polymer studies has greatly increased in the past few years because of the hyphenation between a technique permitting a fast thermal program to yield volatile fragments with a powerful tool for their identification. The classical application of Py C/MS to thermoplastics has been extended recently to thermosets and even to hiopolymers and biocomposites. The use of these techniques to study alternative methods for waste treatment has also been considered as an important and recent feature, showing possibilities for further improvement in the amount of its applications. A brief overview on the identification of polymer additives by Py-GC/MS has also been carried out. 

This book also presents a detailed review of the recent advances on thermoset-based composites and nanocomposites. Finally, Handbook of Thermoset Resins highlights the future directions of research in various areas of thermoset resins. 

Although thermosets are the standard composite matrices, recent advances in thermoplastic technology may change this situation. 

A limitation of DVS-bisBCB polymer is its restriction in building thick (>S0 pm) stacks because of its modmte fracture toughness. The ductility of DVS-bisBCB polymer is significantly enhanced by the addition of an elastomer. Elastomer-toughened thermosets and thermoplastics are widely used in many diverse industries. Recent advances in this area can be found in diree American Chemical Society Symposium Series (20-22). 

The contribution of Babu and Naskar gives a comprehensive overview on the recent developments of the thermoplastic vulcanizates (TPVs) with special reference to the technological advancement. TPVs combine high volume molding capability of thermoplastic with elastomeric properties of thermoset rubber. Therefore, they land themselves to broad area of applications in various fields. 

In recent years new thermoplastic matrices have been developed to improve the stiffness/toughness balance and the service temperature, in comparison to the epoxy thermoset matrices used in high performance composites. These materials, usually referred to as advanced thermoplastic matrices (8), include polymers that have great structural similarities, with aromatic moieties in the main chain spaced by groups of the type diagrammed below. 

With advances in computer technology in recent years, simulation has often provided a very powerful tool to predict the end-use performance from the selected component properties and to establish structure-performance relations with a certain degree of confidence. This approach has been termed in silico design as opposed to in vitro or in vivo. " In silico experimentation - the ability to explore simulations rapidly reduces the need for in vivo experimentation slow, multiple iterations of trial and error for design of new composite structures. The combination of design tools and computer modeling will drive development of new thermosets, with improved performance. This includes new structures based on known materials and the development of new chemistries for selected applications. 

It is not the intention of this chapter to be a review of the literature (if the reader is looking for this. Ref [1] is a recent example). Its purpose is to serve as an introduction to the technique of MTDSC starting with fairly basic and practical matters than progressing onto more advanced levels. It is also intended to serve as a guide to understanding the remaining chapters that deal with three principal classes of polymeric materials, thermosets, thermoplastic polymer blends and semi-crystalline polymers. 

Stenzenberger HD, Recent developments of thermosetting polymers for advanced composites. 

In recent years liquid crystalline thermosetting polymers have been the object of extensive research and patent activity (1-8). The interest in these materials lies in their challenging theoretical implications and in the noticeable potential applications. Highly crosslinked liquid crystalline thermosets turned out to be promising candidates for thin film applications in electronic packaging and as matrix materials for advanced composites due to their superior mechanical properties and heat resistance (4-6) on the other hand, lightly crosslinked networks can be easily oriented by mechanical stress and this results in a change of their optical properties (9). Applications as... 

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