Polyethylene/clay processing

Additives used in final products Fillers barium and strontium ferrites, boron carbide, calcinated clays, calcium carbonate, carbon black, carbon-silica dual phase filler, clays, dolomite, fumed silica, iron oxide, magnesium aluminum silicate, magnesium carbonate, mica, montmorillonite, nickel zinc ferrite, nylon fibers, pulverized polyurethane foam, quartz, silica carbide, soapstone, talc, zinc oxide Plasticizers naphthenic oil, polybutene, aromatic oil, esters of dicarboxylic acid Plasticizers adipates, aromatic mineral oil, paraffin oil, phosphates, phthalates, polyethylene glycol, processing oil, sebacates Antistatics dIhydrogen phosphate of 8-amlnocaprolc add. Iodine doping Antistatics carbon black, quaternary ammonium salt, zinc oxide whisker Antiblocking diatomaceous earth Release propylene wax Slip erucamide+stearamide ... 

A typical fat refining plant (Alfa-Laval process) for the acid washing of fats and oils is illustrated in Fig. 36.8.8 The triglyceride is degummed to remove phosphatides and other impurities such as mucilage, proteinaceous matter, and trace metals by acid washing with citric or phosphoric acids, and then is sent to a bleaching plant where it is dehydrated and treated with an activated clay for the removal of color bodies, heavy metals, chlorophyll, and polyethylene (Fig. 36.9).6... 

As stated previously, styrene-diene triblock copolymers are the most important category of thermoplastic elastomers. Unlike most other TPEs, they can be blended with large quantities of additives without a drastic effect on properties. In almost all applications, the actual triblock copolymer content is less than 50%. Oils are used as a processing aid and do not result in a significant loss of properties if the polystyrene domains are not plasticized. For this reason, naphthalenic oils are preferred. The use of inert fillers such as clays or chalks reduces the cost of the final material. Unlike conventional rubbers, inert fillers do not have a substantial effect on the mechanical properties of TPEs. Thermoplastics such as polyethylene or polypropylene are also used to improve the solvent resistance and can increase the upper service temperature. Polystyrene homopolymer is used as a processing aid, which also increases the hard phase weight fraction and causes the material to stiffen. 

Uses Wetting agent, penetrant for textile processing, clay soils, and firefighting prods. emulsifier for polyethylene emulsions detergent... 

In the last decade, considerable progress was observed in the field of PO/compatibil-izer (predominantly on the base of PO-g-MA)/organo-surface-modified clay nanocomposites. Polyethylene (PE), polypropylene (PP), and ethylene-propylene (EP) rubber are one of the most widely used POs as matrix polymers in the preparation of nanocomposites [3,4,6,30-52]. The PO silicate/silica (other clay minerals, metal oxides, carbon nanotubes, or other nanoparticles) nanocomposite and nanohybrid materials, prepared using intercalation/exfoliation of functionalized polymers in situ processing and reactive extrusion systems, have attracted the interest of many academic and industrial researchers because they frequently exhibit unexpected hybrid properties synergisti-cally derived from the two components [9,12,38-43]. One of most promising composite systems are nanocomposites based on organic polymers (thermoplastics and thermosets). 

Recently, Moad et al. [288,289] designed and prepared novel copolymer intercalant/dis-persant/exfoliant systems that are effective with unmodified clays at low levels (<20% with respect to clay), can be combined with commercial PP and clay in a conventional melt-mixing process, and do not require the use of additional compatibilizers. PP-clay nanocomposites prepared by direct melt mixing using unmodified MMX clays and a copolymer additive added at a level of only 1 wt.% with respect to PP for 5wt.% clay Authors investigated the following two classes of dispersants (1) polyethylene oxide-based nonionic surfactants... 

Gaylord evaluated various clays in polyethylene using peroxide/maleic anhydride treatments [18]. He found very variable results, largely influenced by the nature of the clay surface, and concluded that some filler surfaces could actually inhibit the free radical grafting processes. 

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