Reinforcement with Fillers

Chem. Descrip. Calcium carbonate, coated with < 2% stearic acid Chem. Analysis CaCOj (97.6%), MgCOs (1.5%), moisture (0.2% max.) Uses Coated pigment, filler, reinforcement with easy dispersion in plastic compds., e.g., polyolefins, rigid and flexible PVC, nat. and syn. rubbers and latexes for wire and cable insulation compds., water sealant compds., improved impact props, in PP hardens and stiffens stocks filler, pigment, reinforcing agent in paper, paints, caulks Features Flydrophobic disperses readily Regulatory NSF compliance... 

Good long-term behavior and fatigue and weathering resistance of the composite materials are achieved with filler/reinforcement with permanent polymer/ matrix bond, good resistance to heat, light, water, chemicals, etc. 

Polyester resins, reinforced with glass fibers, are used widely in the construction of process equipment. Some physical and mechanical properties are presented in Table 3.48. Table 3.49 lists various materials used as filler and the properties they impart to different plastics. 

In the pulp and paper industry, anionic and cationic acrylamide polymers are used as chemical additives or processing aids. The positive effect is achieved due to a fuller retention of the filler (basically kaoline) in the paper pulp, so that the structure of the paper sheet surface layer improves. Copolymers of acrylamide with vi-nylamine not only attach better qualities to the surface layer of.paper, they also add to the tensile properties of paper in the wet state. Paper reinforcement with anionic polymers is due to the formation of complexes between the polymer additive and ions of Cr and Cu incorporated in the paper pulp. The direct effect of acrylamide polymers on strength increases and improved surface properties of paper sheets is accompanied by a fuller extraction of metallic ions (iron and cobalt, in addition to those mentioned above), which improves effluent water quality. 

It is important to note here that the presence of rigid filler clusters, with bonds in the virgin, unbroken state of the sample, gives rise to hydrodynamic reinforcement of the mbber matrix. This must be specified by the strain amplification factor X, which relates the external strain of the... 

The use of reinforcing fillers was examined by Seed Wilson (1980). An alumina-fibre cement had a flexural strength of 44 MPa, while one reinforced by carbon fibre had a flexural strength of 53 MPa. Metal reinforcement has also been examined. Seed Wilson (1980) found that a cement reinforced with silver-tin alloy had a flexural strength of 40 MPa. 

Monte Carlo computer simulations were also carried out on filled networks [50,61-63] in an attempt to obtain a better molecular interpretation of how such dispersed fillers reinforce elastomeric materials. The approach taken enabled estimation of the effect of the excluded volume of the filler particles on the network chains and on the elastic properties of the networks. In the first step, distribution functions for the end-to-end vectors of the chains were obtained by applying Monte Carlo methods to rotational isomeric state representations of the chains [64], Conformations of chains that overlapped with any filler particle during the simulation were rejected. The resulting perturbed distributions were then used in the three-chain elasticity model [16] to obtain the desired stress-strain isotherms in elongation. 

This behavior can be explained with the help of the classical rheological theory of suspension of conventional filler reinforced systems. According to this theory [32], rotation of the filler is possible when the volume fraction of clay 4>fflier < 4 critical — (aspect ratiop1. All PBSNCs studied here follow this relation except PBSNC4 (MMT = 3.6 wt%), in which 4)mier (aspect ratio) 1. For this reason, in... 

Plastics, both thermoplastic and thermosetting, will deform under static load. This is known as creep. For this reason those materials whose prime function is mechanical are generally reinforced with mineral filler or short fibres, or else oriented by drawing. Many components have a limit on acceptable deformation, and the predicted creep strain at the end of life will be fed back to define either a maximum load, or mechanical dimensions large enough for the component to remain within the limitations on strain. Creep becomes more pronounced at higher temperatures. 

Nanocarbon composites can be broadly divided into three kinds, each with some possible subdivisions. Examples of these composites and their schematic representations are presented in Fig. 8.1. The first type corresponds to composites where the nanocarbon is used as a filler added to a polymer matrix analogous, for example, to rubber reinforced with carbon black (CB). The second consists of hierarchical composites with both macroscopic fibers and nanocarbon in a polymer, such as a carbon fiber laminate with CNTs dispersed in the epoxy matrix. The third type is macroscopic fibers based... 

Bledzki, A.K., Reihmane, S. and Gassan, J. (1998). Thermoplastics reinforced with wood fillers a literature review. Polymer and Plastics Technology, 37(4), 451 68. 

Table 3.18 shows the effects of several lubricating fillers on the friction properties of polyamides 6 or 66 possibly reinforced with glass or carbon fibres. 

General chemical properties are subject to the compatibility of the fillers and reinforcements with the ambient conditions. If the fillers are well adapted, the chemical properties are the same for filled and neat polymers. 

More than 60% of polyamides are reinforced with glass fibres (in more than 80% of reinforced grades) or mineral fillers (more than 10%). 

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