Effects of Fillers on Properties and Performance

A filler is defined as any material added to a polymer that is significantly different structurally or chemically from the basic polymer. By convention this exempts such materials as plasticizers or compatible resins which in effect become part of the continuous plastic phase. Even the addition of a rubbery second phase such as exists in high impact polystyrene is excluded although it can be distinguished from the polystyrene phase microscopically because the material acts in most respects as a homogeneous phase. 

The fillers used cover a wide variety of materials. Some of the typical ones are listed in Table 3-1. They can be grouped in several ways in terms of their structure, the way they interact with the polymer matrix, or in terms of their composition. Structurally the fillers may be aggregates with essentially round or polyhedral shapes such as clay or chalk, plates or flakes such as mica, or lamellar glass, fibers such as fiber glass, asbestos, or synthetic fibers, or cellular material such as vermiculite, foamed glass, or hollow glass beads. 

The second way that the fillers can be characterized is by their interaction with the polymer matrix. The fillers can be adherent to the polymer matrix whether inherently or by special surface treatment. The fillers may absorb the polymer phase because of high surface area and inherent wettability. They can react chemically with the polymer material to form a chemical bond, again, both by inherent structure or by suitable surface treatment. The filler can be catalytic to the structure and, in addition to acting as a filler can cause crosslinking of the structure, notably in the case of carbon black. Finally, the filler can be inert and nonadherent to the polymer and remain as just a void filler. 

The chemical nature of fillers can cover a wide range, some of which have been indicated. Carbon black is an inorganic residue 

In general, the addition of nonadherent filler is an undesirable method of filling plastics materials. The fillers add bulk and improve some properties such as the compressive strength and modulus, and they generally improve the heat resistance and reduce the coefficient of thermal expansion. Because of the nonadherence, however, they make the materials brittle and weak in tension and bending. This results from the fact that each particle acts as a stress riser, increasing 

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Applications. Optical microscopy finds several important applications in filled systems, including observation of crystallization and formation of spherulites and phase morphology of polymer blends. " In the first case, important information can be obtained on the effect of filler on matrix crystallization. In polymer blends, fillers may affect phase separation or may be preferentially located in one phase, affecting many physical properties such as conductivity (both thermal and electrical) and mechanical performance. 

MD simulations can be performed in many different ensembles, such as grand canonical (pVT), microcanonical (NVE), canonical (NVT) and isother-mal-isobaric (NPT). The constant temperature and pressure can be controlled by adding an appropriate thermostat (e.g., Berendsen, Nose, Nose-Hoover and Nose-Poincare) and barostat (e.g., Andersen, Hoover and Berendsen), respectively. Applying MD into polymer composites allows us to investigate into the effects of fillers on polymer structure and dynamics in the vicinity of polymer-filler interface and also to probe the effects of polymer-filler interactions on the materials properties. 

The ease of mixing has two aspects, one is ease of incorporation and the other is dispersion. How can the ease of mixing be quantified and how can it be related to the appropriate properties of a filler These questions concern characterisation of fillers and may be called the property-processability relationship. Whereas the effect of fillers on the performance of vnlcanisates has been quite extensively researched and the reinforcing mechanisms have been examined, the ease of mixing has not been investigated as much. This chapter is also limited to primarily qualitative discussions. Scientific investigation is very much in order. 

In the 1980s, several authors proposed the use of composite polymer electrolytes. The solutions they proposed depended on the electrochemical application, i.e. lithium batteries, fuel cells, etc., which determined the properties required. This chapter reviews the development and properties of composite polymer electrolytes used in lithium batteries and proton exchange membrane fuel cells (PEMFC). The effects of fillers on electrolyte properties are discussed in terms of electrochemical performance, and also in terms of polymer matrix morphology and dynamics. Data from the literature are compared in order to determine the effects of the manufacturing... 

In order to produce high-performance elastomeric materials, the incorporations of different types of nanoparticles such as layered silicates, layered double hydroxides, carbon nanotubes, and nanosilica into the elastomer matrix are now growing areas of rubber research. However, the reflection of the nano effect on the properties and performance can be realized only through a uniform and homogeneous good dispersion of filler particles in the rubber matrix. 

In addition, newer aspects, such as the effects of sustainable materials based on starch on the macro or nanostructure and subsequent processing, thermomechanical properties and performance properties of plasticized starch pol5mciers have been examined (10). Specific structures and the resulting properties are controlled by many specific factors, such as filler shape, size and surface chemistry, processing conditions and environmental aging. In case of nanosized biocomposites, the interfadal interactions are extremely important to the final nanostructures and performance of these materials. 

Nontoxic Citrates Nontoxic citrate plasticizers derived from natural citric acid, such as triethyl citrate (TC), tributyl citrate (TBC), acetyl triethyl citrate (ATC), acetyl tributyl citrate (ATBC), and triacetine, have been shown to be effective plasticizers for PLA [27-29]. Some gas permeability tests have been performed to assess the potential use of PLA and nontoxic citrate plasticizer blends in food packaging and other applications. The effect of ATBC on PLA barrier properties was studied by Coltelli et al. [30] using PLA mixed with ATBC (10-35 wt%), followed by compression molding. Yu et al. [31] blended PLA/ATBC mixmres with carbon black (CB) to form electrically conductive polymer composites. Fourier transform infrared (FTIR) experiments revealed that the interaction between the PLA/ATBC matrix and the CB filler was increased by the addition of ATBC. Water vapor permeability values decreased with an increase in ATBC content (at constant CB levels). For example, at 30wt% CB, the WVP of the PLA decreased from 0.66 x 10 kgm/(msPa) (at 0% ATBC) to 0.10 X 10 kgm/(msPa) with the addition of 30% ATBC. 

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