Antistatic fillers

Antioxidants, antistats, fillers, flame retardants, UV screeners, slip agents, metal deactivators, whiteners, pigments, and dye receptors are added to polyolefin powder, chips, or granules prior to fiber manufacture. These additives help to overcome fiber sensitivity to heat, UV radiation, and flame and to improve some other properties. In the melt-in-melt system, PP fiberforming polymers can be mixed with these additives to achieve specific formulations. 

Surfa.cta.nt-TypeAntista.ts, Inherently conductive antistats have the advantage of not being dependent on atmospheric moisture to function. Thek drawbacks include expense, coloration of the plastic, and alteration of the mechanical properties of the plastic. The added stiffness caused by conductive fillers may not be a problem with a rigid container, but it can be a problem for a flexible bag. 

Copolymers were also used in gramophone record formulations (Formula 6). No filler can be tolerated and stabilisers and lubricants are chosen that give records of minimum surface noise. Antistatic agents may also be incorporated into the compound. 

Any review devoted to conducting composites would be incomplete if the application fields of such composites were not described even if briefly. One of the first, if not the foremost, examples of the utilization of the CPCM is antistatic materials [1], For the materials of this kind resistivity q of less than 106 to 108 Ohm cm is not required, and this is achieved by introducing small amounts (several per cent) of a conducting filler, say, carbon black [4],... 

Accelerators Antioxidants Antistats Blowing Agents Colorants Conductive EMI Shelving Fillers... 

Hydrolysis of polyamide-based formulations with 6 N HC1 followed by TLC allows differentiation between a-aminocaproic acid (ACA) and hexamethylenedi-amine (HMD) (hydrolysis products of PA6 and PA6.6, respectively), even at low levels. The monomer composition (PA6/PA6.6 ratio) can be derived after chromatographic determination of the adipic acid (AA) content. Extraction of the hydrolysate with ether and derivatisa-tion allow the quantitative determination of fatty acids (from lubricants) by means of GC (Figure 3.27). Further HC1/HF treatment of the hydrolysis residue, which is composed of mineral fillers, CB and nonhydrolysable polymers (e.g. impact modifiers) permits determination of total IM and CB contents CB is measured quantitatively by means of TGA [157]. Acid hydrolysis of flame retarded polyamides allows to determine the adipic acid content (indicative of PA6.6) by means of HPLC, HCN content (indicative of melamine cyanurate) and fatty acid (indicative of a stearate) by means of GC [640]. Determination of ethylene oxide-based antistatic agents... 

Besides their two main uses as reinforcing fillers and pigments, small amounts of carbon blacks are used by the electrical industry to manufacture dry cells, electrodes, and carbon brushes. Special blacks are used to give plastics antistatic or electrical conduction properties. Another application is the UV stabilization of polyolefins [4.31]. 

Conductive Fillers. The incorporation of sufficiently large amounts of blacks can impart antistatic (resistivity 106-109 Q cm) or conductive (< 106 Q cm) properties to plastics. 

Concentration of antistats in plastics is mostly 0.1 to 2 %. Special grades of electroconducting (EC) carbon black are used in PO at levels higher than 10 % (Accorsi and Yu, 1998). Other conducting fillers incorporating antistatic effects, such as metals or organic semiconductors (e.g. polypyrrole) are not commonly used in plastics for contact with food. 

For specialised applications where electrical conductivity is required, such as antistatic flooring or shielding of electromagnetic induction, specific carbon black pigment/filler is used. Copper and nickel metal powders have also been studied (112). A review is available of the electrical properties of polymers filled with different types of conducting particles (416). 

The characteristic threshold behaviour of conductive composites is an unsatisfactory feature for many applications, both because the poor mechanical properties incurred at concentrations where conduction is obtained cannot be tolerated, and because the high level of conductivity above the threshold is not required or even not desirable. Thus a common requirement is for an antistatic material which has good plastics properties, sufficient conductivity to allow charges to leak away, and sufficient resistivity to prevent dangerous shocks to personnel who may become accidentally connected to mains electrical supplies through it. Unfortunately, the very steep slope of the conductivity versus filler concentration curve in the region of the threshold makes it very difficult to manufacture materials with reliable intermediate conductivities. 

Suspensions of polyacetylene were prepared as burrs or fibers (46) by using a vanadium catalyst. When the solvent was removed, films of polyacetylene were formed with densities greater than that prepared by the Shirakawa method. These suspensions were mixed with various fillers to yield composite materials. Coatings were prepared by similar techniques. Blends of polypyrrole, polyacetylene, and phthalocyanines with thermoplastics were prepared (47) by using the compounding techniques typically used to disperse colorants and stabilizers in conventional thermoplastics. Materials with useful antistatic properties were obtained with conductivities from 10" to 10" S/cm. The blends were transparent and had colors characteristic of the conducting polymer. For example, plaques containing frans-polyacetylene had the characteristic violet color exhibited by thin films of solid trans-polyacetylene. 

Other additives that may be used by PU manufacturers include curing agents, flame retardants, fillers, antiaging agents, colorants, antistatics, biocides, and release agents. ... 

Performance of other additives Fillers arc instrumental in improving the performance of other additives. Antistatics, blowing agents, catalysts, compatibilizers, coupling agents, organic flame retardants, impact modifiers, rheology modifiers, thermal and UV stabilizers are all influenced by a fillet s presence. 

One single property of filler - electric conductivity - affects many properties of the final products. These properties include electric insulation, conductivity, superconductivity, EMI shielding, ESD protection, dirt pickup, static decay, antistatic properties, electrocatafysis, ionic conductivity, photoconductivity, electromechanical properties, thermo-electric conductivity, electric heating, paintability, biocompati-bilify, etc. Possession of one of these properties in a polymer can make it useful in industiy and eveiyday use. Examples are given in Chapter 19. Here, the electrical... 

Many filled systems are exposed to irradiation during processing or use. Such processes include radiation crosslinking and vulcanization, development of antistatic properties, production of y-radiation shields, and sterilization. The effect of fillers in these applications is studied. 

Conductive fillers, intrinsically conductive polymers, and organic additives are used as antistatics. There is no common product available which has a combination of the above. The only known combinations are particulate and fibrous conductive fillers, which are claimed to produce a better effect. 

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