Particulate fillers, polymers containing

There has also been some interest in polymers containing particulate mineral fillers. 

Shear yield behaviour of polymer melts containing plate-like filler particles is also prevalent and is clearly shown in Fig. 8 for talc-filled polystyrene. In this system an estimate was made of shear yield values, which were found to increase with increasing particle loading and decreasing particle size. These results are compared with reported yield values for other particulate-filled polymers in Table 2. It is evident that shear yield values also depend on the particle type and thermoplastic matrix used. 

Fig. 7. Dependence of modulus on filler content for a polymer containing a hard, particulate filler. Reproduced with permission from Ferringo TH (1987) In Katz HS, Milewski JV (eds) Handbook of fillers for plastics, Van Nostrand Reinhold...

Fig. 8. Dependence of conductivity on filler content for a polymer containing carbon black, a particulate conducting filler. Reproduced with permission from Blythe AR (1979) Electrical properties polymers, Cambridge University Press...

Polymer nanocomposites are combinations of polymers containing inorganic or organic fillers of definite geometries (fibres, flakes, spheres, particulates and so on). The use of fillers, which have one dimension on the nanometre scale, enables the production of polymer nanocomposites. Functional nanocomposites with specific properties can be custom-made by combining metal nanoparticles (MNP) into the polymer matrix. 

Bone is a natural composite of apatite-collagen. So a composite of polymer matrix containing bioactive particulate filler is a natural choice for substituting cortical bone. Bone substitutes can be easily made by using hydroxyapatite (HA) particles as the bioactive component because of its close similarity with bone apatite and its excellent bioactivity. So a composite made of HA with polymer matrix provides... 

Table 2.5 contains a general equation, Eq. (2.35), for the effect of particulate fillers on the tensile strength of a polymer, a common modification of this equation by Nicolais and Narkis, (Eq. (2.36)), and an additional equation proposed by Piggott and Leidner,... 

The main fields of application of particulate filled polymers is shown in Figure 2. As was mentioned earlier, the major benefit of the application of fillers and reinforcement is increased stiffness and HDT. Specific applications which must be mentioned here are garden furniture (CaC03), air-filter covers, heater boxes (talc) for cars, washing machine soap dispensers (talc), etc. Bumpers are usually made from multi-component PP systems containing a PP homo- or copolymer, an elastomer and a filler. In order to demonstrate the usual property range of particulate filled polymers. Table 1 presents the most important characteristics of several commercial grade PP composites. 

Rheological data can provide useful information about the influence of filler type, content and surface treatment on the overall melt viscosity of polymer containing particulate additive. Many reports exist describing these effects [44-46]. 

The extensional behavior of a polymer S3 tem containing particulate filler was studied experimentally by Han and Kim [86]. It was found that, at a fixed extension rate, the extensional viscosity increased wifit increasing filler concentrations because the solid particles of calcium carbonate did not deform under stretching and hence exerted more resistance to the flow of the molten fhreadline wifii an increase in concentration. 

Beyer G. Flame retardant properties of EVA-nanocomposites and improvements by combination of nanofiller with aluminium trihydrate. Fire Mater, 2001 25 pp. 193-197. Rothon NR. Particulate-Filled Polymer Composites. Harlow Longman Scientific 1995. Hawroth B, Raymond CL, Sutherland I. Polyethylene compounds containing mineral fillers modified by acid coatings. 2. Factors influencing mechanical properties. Polym Eng Sci, 2001 41 pp. 1345-1364. 

Commercial grades of polymer may contain, in addition to glass fibre, fire retardants, impact modifiers and particulate reinforcing fillers. Carbon fibre may be used as an alternative to glass fibre. 

Lower-density E-plastomers have found alternate use in cast film processes to make elastic film laminates with good breathability which contain laminates of liquid impermeable extensible polymeric films with extensible-thermoplastic-polymer-fiber nonwovens and nonwoven webs of polyethylene-elastomer fibers as the intermediate layers. The development relates to a breathable film including an E-plastomer and filler that contributes to pore formation after fabrication and distension of the film. The method and extent of distension is designed to produce a breathable film by stretching the film to form micropores by separation of the film of the E-plastomer from the particulate solids. This film is useful for manufacture of absorbent personal-care articles, such as disposable diapers and sanitary napkins and medical garments. In detail, these constructions comprise a liquid impermeable extensible film comprising polyolefins. The outer layer contains extensible-thermoplastic-polymer-fiber nonwovens, and an elastic intermediate layer contains nonwoven webs of fiber E-plastomers. The intermediate layer is bonded to the film layer and the outer... 

Crosslinked polymers are widely used as dental materials (1-31. Perhaps the most challenging application is in the restoration of teeth (4). The monomers must be non-toxic and capable of rapid polymerization in the presence of oxygen and water. The products should have properties comparable to tooth enamel and dentin and a service life of more than a few years. In current restorative materials such properties are sought using so-called "dental composites" which contain high volume fractions of particulate Inorganic fillers (5-71. However in the present article attention is concentrated on one commonly used crosslinked polymeric component, and on the way in which some of its properties are influenced by low volume fractions of fillers. 

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