Natural injectable composites applications

Savastano H Jr, Santos SF, Radonjic M, Soboyejo WO et al (2009) Fracture and fatigue of natural fibre-reinforced cementitious composites. Cement Concr Compos 31 232-243 79. Rahman WA, Tin SL, Razak RA et al (2008) Injection moulding simulation analysis of natural fibre composite window frame. J Mater Process Technol 197 22-30 Toledo FRD, Andrade SF, Fairbaim EMR, Melo FA et al (2009) Durability of compression molded sisal fibre reinforced mortar laminates. Construct Build Mater 23 2409-2420 Pillai MS (2006) Applications of natural coir fibre, proceedings, natural fibres vision 2020, New Delhi 8-9th December... 

The term water is used to describe potable water that is freshly drawn direct from the public supply and is suitable for drinking. The chemical composition of potable water is variable and the nature and concentrations of the impurities in it depend upon the source from which it is drawn. Although potable water must be both palatable and safe to drink, for most pharmaceutical applications potable water is purified by distillation, ion exchange treatment, reverse osmosis, or some other suitable process to produce purified water . For certain applications, water with pharmacopeial specifications differing from those of purified water should be used, e.g. water for injection see Sections 9 and 18. 

In recent years starch, the polysaccharide of cereals, legumes and tubers, has acquired relevance as a biodegradable polymer and is becoming increasingly important as an industrial material (Fritz Aichholzer, 1995). Starch is a thermoplastic polymer and it can therefore be extruded or injection moulded (Balta Calleja et al, 1999). It can also be processed by application of pressure and heat. Starch has been used successfully as a matrix in composites of natural fibres (flax, jute, etc.). The use of starch in these composites could be of value in applications such as automobile interiors. An advantage of this biopolymer is that its preparation as well as its destruction do not act negatively upon the environment. A further advantage of starch is its low price as compared with conventional synthetic thermoplastics (PE, PP). 

Use of 3D foams is also a popular method for bone regeneration applications, although they are most often employed for trabecular bone regeneration [152,154]. There are a few methods utilized to create foams for this application, one of the most popular being a polymer foam replication technique, in which a polymer foam is either electrosprayed or immersed into a HAp/bioactive glass particle slurry in order to fully coat the foam and create a trabecular bone-like aichitecture. However, other methods are also utilized, including creating composite foam solutions that are injectable and form once inside the body [153]. Results of Fu et al. [152] have indicated mechanical properties similar to those of natural trabecular bone. 

The possibilities for making bonded structural sandwich elements in a variety of materials are very real. However, whilst there exist structural examples such as aluminium honeycomb panels (used in aircraft and transport applications) and metal skinned foam sandwich panels (used as the monocoque chassis in refrigerated transport applications), these composite constructions are normally utilised in non- or semi-structural ways. Typical skin materials are steel, aluminium, GRP and plywood, and common core materials are rigid foam polystyrene, polyurethane, polyisocyanurate, PVC, and honeycombed aluminium. In some instances the foam core is injected between the skins and adheres to them in others, adhesives are used to bond the separate components together. The nature of the manufaeturing process depends on the type of structure to be made, and the degree of investment in produetion maehinery. Both flat and eomplex eurved forms ean be made by a hand lay-up process as well as in an automated way. 

Another application is in flexible keypads, where PEBA replace typical metal and spring composites. The use of such resins allows the keypad to be injection molded in one piece. The tactile nature of these components is maintained by varying the thickness of the resin within each key on the pad. By varying the thickness, the force required to depress the key can be altered. In this application, PEBA offer flex"fatigue resistance, excellent melt flow characteristics during molding and dimensional stability. 

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