Filler types

Fillers. These are used to reduce cost in flexible PVC compounds. It is also possible to improve specific properties such as insulation resistance, yellowing in sunlight, scuff resistance, and heat deformation with the use of fillers (qv). Typical filler types used in PVC are calcium carbonate, clays, siHca, titanium dioxide, and carbon black. 

Thermal Analyses. Thermal analysis often complements x-ray data in providing information on phase composition. The thermal behavior of aluminum hydroxides is particularly important in filler type appHcations. 

Approximately 600,000 metric tons of aluminum hydroxides were used in chemical appHcations in the United States in 1988 40% as fillers, 45% for the production of aluminum chemicals, and 15% for various other uses. Carpet backing was the principal filler type appHcation foUowed by polyester products. 

Base Resin Filler Type and Content (%) Stress (psi) Strain (%) Hours Apparent Modulus (103 psi) Hours ... 

Depending on the namre of filler, type of dispersion, and method of preparation, the nanocomposites can be divided into subclasses. 

Analysis of inorganic fillers in plastics and rubber materials is normally accomplished by ashing material in a muffle furnace at a temperature of 550°C. An IR spectrum of the resulting ash, sometimes as a paraffin oil mull is then obtained to identify the filler type. Examination of the ash by XRF and/or X-ray diffraction can also provide useful information to help identify complex systems. 

The carbon black generated by a fire from a rubber source increases the smoke density other products are highly toxic and often corrosive. The halogens, phosphates, borates, and their acids evolved during a fire corrode metals and electrical and electronic equipment. Hence many of the fire retardants described below cannot be used in situations where the toxic gases evolved will create their own hazards. In these cases inorganic hydroxides are used, at filler-type addition levels. Aluminium hydroxide and magnesium hydroxide are used as non-toxic fire retardant systems. 

Polymer Filler type Percolation threshold Volume or surface realativity Processing method... 

It is estimated that over one million tons of mineral fillers were used in thermoplastic applications in western Europe in 1986 [2], and the figure is doubtless much greater today. Mineral fillers are used to some extent in virtually all the commercially important thermoplastic polymers but, in volume terms, the principal markets are in PVC and polyolefins, where calcium carbonate dominates the filler types with over 80% of the volume consumption [2]. 

The importance of the use of mineral fillers to the growth of applications for thermoplastic polymers has already been described. The addition of such materials affects most of the significant properties of the matrix, some beneficially, others detrimentally. Only some of these altered properties are important to the use of thermoplastics, and an appreciation of what these are is critical to identifying those filler characteristics that are important and in understanding how certain filler types and production methods have come to dominate the market. 

One of the principal limitations of thermoplastic polymers is their low stiffness (modulus), especially at elevated temperatures (heat distortion). Certain filler types are very good at improving these properties and this is another of the main reasons why fillers are used in these polymers. 

Further details on some of these processes can be found in the work by Wills [45] and in the section on individual filler types. 

Aluminium and magnesium hydroxides are difficult to produce directly in any useable form from their natural ores. Filler grade calcium carbonate is widely produced from natural sources, but grinding costs appear to become prohibitive when ultra-fine particles are required and precipitation procedures then become competitive. Further details of precipitation procedures will be found under the specific filler types. 

Morphology is one of the key factors determining the performance of mineral fillers in all polymers including thermoplastics. While an apparently simple concept, it is very complex in practice, and probably accounts for a great deal of the problems and misconceptions that are experienced in this field. A detailed discussion of the subject has recently been given by Rothon and Hancock [75]. Because of its importance in determining the production methods that are used and the choice of filler types its characterisation is covered in some detail here. 

Production, Properties and Applications of the Principal Filler Types... 

The end performance of the filler is also critically influenced by how it is presented within the polymer especially the state of mixing within the composition. With some filler types it is possible to enhance their efficiency, or commercial viability, by the way in which they are combined and melt processed with the polymer. In some instances this has been achieved through iimovation in processing machinery design. 

Since polymer melt flow behaviour is strongly affected by the nature of the filler type, including its morphology, surface chemistry and concentration, rheological studies can also assist in the development of formulations designed to facilitate industrial processability. 

Fig. 9. The effect of magnesium hydroxide filler type on the dynamic storage modulus G of polypropylene (PP) at 200 °C (strain amplitude 10%, filler level 60% by weight). Magnesium hydroxide fillers differed in origin particle size and treatment. Mean particle size (pm) type A ( ), 7.7 type B (+), 0.9 type C ( ), 4.0 type D ( ), 0.53 type E, stearate-coated version of type A, (X), 3.7 unfilled PP (O) [36]...

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. 

In multiphase filled polymer compositions, which may contain mixed filler types, combinations of fillers and fibres, or proportions of filler and a secondary modifying polymer, such as an elastomer, the spacial distribution of the phases has a direct bearing on the properties of the composite. In the case of the last mentioned system, the rubber may encapsulate the filler, be present as discrete droplets within the thermoplastic matrix or co-exist in both structural forms [80,81]. 

However, controlled shearing experiments using titanium dioxide in PDMS and hnear low density polyethylene demonstrated that with this filler type, particle erosion was the predominant dispersion mechanism [68,119]. 

Kumar, R., Howdle, S. and Munstedt, H. (2005) Polyamide/silver antimicrobials Effect of filler types on the silver ion release. /. Biomed. Mater. Res. Appl. Biomater., 75 (2), 311—319. 

Tensile strength, modulus at a given elongation and elongation at break depend on the rubber type and the reinforcing filler type and... 

The properties of a syntactic material can be varied quite significantly by changing the filler type, the binder-filler ratio, and the manufacturing and curing techniques. Syntactic plastics are heavier than conventional foams, with apparent densities of 200-800 kg/m3. 

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