Processing, thermoplastics material concepts

An attempt to use a recently patented concept (Dispersed Nano-Objects Protective Encapsulation—DOPE process) intended to disperse carbon nanotubes in polymeric matrices was reported. Physically cross-linked alginate capsules were successfully formed in the presence of either cellulose whiskers or microfibrillated cellulose [153]. The resulting capsules were extruded with a thermoplastic material. Another possible processing technique of nanocomposites using cellu-losic nanoparticles in the dry state present in the filtration of the aqueous suspension to obtain a film or dried mat of particles followed by immersion in a... 

This chapter focuses on the primary processing of thermoplastic materials. It begins with material concepts used in processing. The chapter continues with processing techniques, and each process is outlined, equipment requirements are specified, and processing parameters are discussed. 

In general, two different concepts of polymer binders can be applied in bipolar plates. First, the binder material can be polymerized or cross-linked in situ in the composite during molding of the plate (resin method). Second, a thermoplastic polymer material can be used in the compounding process (thermoplastic method). 

This relatively new type of composite material constitutes a novel breed of thermoplastic polymer composite. MFCs originated when the concept of attempting to reinforce one type of polymer with another was combined with that of strengthening a polymer through drawing. This work culminated in the creation of microfibril reinforced composites in the early 1990s, which was soon followed by the development of the continuous manufacturing process used today [2,3]. 

As a general rule, self-reinforced composites consist either of layers of highly-oriented thermoplastic textiles [4-7] or of a combination of self-reinforced textiles and a similar thermoplastic matrix material, which is added in the form of a film, powder or melt [1]. These are then hot-compacted to structurally consolidated mono-composites under pressure and temperature in a pressing process. For the most part, the fiber composite concept relies upon the embedding of stretched endless fibers or tapes made of PP into a chemically identical matrix. 

An exceptional advantage of self-reinforced thermoplastic composites is that they can be thermally recycled, but also reprocessed due to their polymer purity. This can be done by either returning the composite to a melted state or by simply re-granulating it. Thus, this process does without the complicated and expensive separation of the components, because an actual single-material system is on hand. Such a simple and useful recycling concept (in regard to material reuse) for the quantities currently in circulation has yet to be developed for the established foreign fiber reinforced thermoplastics. 

This chapter reviews the main results obtained in the fields of starch-filled plastics and thermoplastic starch, paying particular attention to the concepts of gelatinization, destructurization, extrusion cooking, and the use of com-plexed starch in specific synthetic polymers. Aspects such as processability, the physicochemical and physicomechanical properties and the biodegradation behaviour of starch-based materials on the market are briefly considered. 

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