Influence of Fillers

Fillers can reduce the effects of radiation. The reason may be the interception of free radicals on the filler surface, absorption of radiation by fillers, or altered oxygen diffusion [77]. 

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Figure 3.12 Influence of fillers on modulus-temperature relationship a, PA-6 neat b, 30 wt % mineral c, 15 wt % glass fibers d, 30 wt % glass fibers e, 50 wt % glass fibers.17...

Thermoplastic elastomeric compositions from reclaimed NR and scrap LDPE with 50 50 mbber/plastic ratio shows good processability, ultimate elongation, and set properties. Polymer blends of reclaimed mbber and LDPE exhibit higher viscosity over the range of shear rate at various temperatures compared to virgin NR-LDPE blends due to the influence of filler present in the reclaimed mbber (Eigure 38.7) [109]. 

The influence of fillers has been studied mostly at hl volume fractions (40-42). However, in addition, it is instructive to study low volume fractions in order to test conformity with theoretical predictions that certain mechanical properties should increase monotonlcally as the volume fraction of filler is Increased (43). For example, Einstein s treatment of fluids predicts a linear increase in viscosity with an increasing volume fraction of rigid spheres. For glassy materials related comparisons can be made by reference to properties which depend mainly on plastic deformation, such as yield stress or, more conveniently, indentation hardness. Measurements of Vickers hardness number were made after photopolymerization of the BIS-GMA recipe, detailed above, containing varying amounts of a sllanted silicate filler with particles of tens of microns. Contrary to expectation, a minimum value was obtained (44.45). for a volume fraction of 0.03-0.05 (Fig. 4). Subsequently, similar results (46) were obtained with all 5 other fillers tested (Table 1). 

Table 1. Influence of fillers on Vickers Hardness Number...

III.2 In another article on bone cements [Vallo, C, Influence of filler content on static properties of glass-reinforced bone cement, J. Biomed. Mater. Res., 53(6), 717 (2000)], the following data for the critical intensity factor in these same glass-bead-fllled PMMA composites as was used in Problem 5.III.1 are given ... 

Several studies have considered the influence of filler type, size, concentration and geometry on shear yielding in highly loaded polymer melts. For example, the dynamic viscosity of polyethylene containing glass spheres, barium sulfate and calcium carbonate of various particle sizes was reported by Kambe and Takano [46]. Viscosity at very low frequencies was found to be sensitive to the network structure formed by the particles, and increased with filler concentration and decreasing particle size. However, the effects observed were dependent on the nature of the filler and its interaction with the polymer melt. 

Dannenberg, E. M. Influence of filler-elastomer interactions on reinforcement behavior . In Le renforcement des elastomeres. Paris CNRS 1975, pp. 129-135... 

Influence of filler content on the positron lifetime parameters... 

Table VI. Influence of Fillers on Strength of Beech Plywood1 Bonded with Formulations in Nonemulsifiable Diisocyanate (PMDI) and Tannin Extracts (50% Solutions)...

Capps, R.N. Beumel, L.L. "Influence of Fillers on Constrained-Layer Vibration-Damping Capabilities of Chlorobutyl Elastomers", J. Acoust. Soc. Am. 83, S82(A), 1988. 

Considerable effort has been spent to explain the effect of reinforcement of elastomers by active fillers. Apparently, several factors contribute to the property improvements for filled elastomers such as, e.g., elastomer-filler and filler-filler interactions, aggregation of filler particles, network structure composed of different types of junctions, an increase of the intrinsic chain deformation in the elastomer matrix compared with that of macroscopic strain and some others factors [39-44]. The author does not pretend to provide a comprehensive explanation of the effect of reinforcement. One way of looking at the reinforcement phenomenon is given below. An attempt is made to find qualitative relations between some mechanical properties of filled PDMS on the one hand and properties of the host matrix, i.e., chain dynamics in the adsorption layer and network structure in the elastomer phase outside the adsorption layer, on the other hand. The influence of filler-filler interactions is also of importance for the improvement of mechanical properties of silicon rubbers (especially at low deformation), but is not included in the present paper. 

Table 3. Influence of filler and plasticizer concentration on physical mechanical parameters of composition HI.

Caneron CG, McGinity JW. Controlled-release theophylline tablet formulations containing acrylic resins, part 3 influence of filler excipient. Drug Dev Ind Pharm 1987 13(2) 303-318. 

Figure 5.2 shows the influence of filler concentration on the density of polymer calculated from the following equation dr... 

Figure 7.36. Influence of filler s surface on microheterogeneity coefficient of copolymers. [Adapted, by permission, from Vasnev V A, Tarasov A I, Istratov V N, Ignatov V N, Krasnov A P, Kuznetsov A I, Surkova I N, Reactive Functional Polym., 26, Nos.1-3, 1995, 177-83.]...

This section adds information on the influence of filler on the wear behavior of... 

There are several reports on the influence of fillers on shrinkage. " Figure 8.56 shows mold shrinkage vs. concentration of filler. Mold shrinkage can be reduced to half of the value for unfilled resin by the incorporation of mica. Additional reduction of shrinkage is possible if the interaction between filler and the matrix can be increased. This can be achieved by reacting polypropylene with maleic anhydride. ... 

Adhesives have very broad range of performance requirements. The performance spectrum ranges from pressure sensitive products where almost minimal adhesion is required, to extremely high performance adhesives with strength equivalent to that of metals. But the scope of the adhesive s performance goes well beyond adhesive strength. Flowability, force to adhere and mechanical, thermal, electrical, barrier, and optical properties as well as chemical and weather resistance and rheological behavior all must be considered in adhesive formulations. These essential parameters are discussed below from the point of view of the influence of fillers. 

Table 6. Influence of Fillers on Light Stability of LDPE Blown Film Florida Exposure KLY to 507, Retention of Elongation...

In examining such envelopes, attention must be paid to the possible influence of filler on crystallization in the matrix. Eirich25 quotes Studebaker s findings that crystallization is increased in the presence of fillers. This is probably the direct result of strain magnification (discussed in Sect. 5). In non-crystallizable polymers, of course, strain magnification causes no such effects, and envelopes for the two types of polymers are therefore not comparable. 

Elastomer interaction with carbon black or silica is very difficult to estimate and correct. On the other hand, it is much easier to take into account the actual volume of aggregate in the mix, and it has been proposed that a corrected volume fraction 4>c be used, which integrates the influence of filler stmcture as represented by DBF (Medalia, 1974 Kraus, 1970 Medalia, 1973). 

The influence of filler is not limited to this enhancement of the non-Newtonian behavior of elastomers. At very small shear rates, filled green compounds also exhibit an additional increase of viscosity that cannot be explained by strain amplification. This effect is usually attributed to the existence of the filler network the direct bonding of reinforcing objects by adsorbed chains implies a increased force to be broken. Obviously this influence can be observed only at very low strain, because a very small increase of interaggregate distances immediately implies a desorption of the bridging elastomeric chains. 

Pollock, D.K. Influence of filler/binder composition on the properties of a inert matrix CR system. Proc. Int. Symp. Control. Release Bioact. Mater. 1997, 24, 481-482. 

Table 28 Influence of fillers and reinforcing materials on the property profiles of plastics see also [104, 109, 110, 111, 112,113]... 

Jikan, S. S , Ariff, Z. M., Ariffin, A. (2010). Influence of filler content and processing parameter on the crystallization behaviour of PP/kaolin composites. /. Therm. AnaLCcdorm., 101,1011-1017... 

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