Polypropylene processing aids

Tile is based mainly on vinyl chloride and vinyl acetate copolymers. Some polypropylene tile systems have recently been introduced. A petroleum resin is usually employed as an extender and processing aid conventional vinyl plasticizers and stabilizers also are incorporated. Reinforcing fibers and limestone constitute the remainder of the tile composition the fibers contribute hot strength for processing and dimensional stability in the finished tile, limestone supplies bulk at an economical cost. Stable pigments are also incorporated. Since tile is installed on and below grade level, it is important that the finished product be resistant to the effects of moisture and alkali. 

U.S. Pat. No. 6,971,211 [110] (by Crane Plastics Company, TimberTech) discloses a cellulosic fiber-polymeric composite comprising a cellulosic filler in an amount of 30-70% by weight, a plastic material, such as PVC and polypropylene in an amount of 30-70% by weight. The PVC material may include 1-10 parts of a stabilizer, 2-12 parts of a lubricant, and 0.5-8 parts of a process aid per 100 parts of the PVC resin. The polypropylene material includes 10-20 parts of a lubricant per 100 parts of the polypropylene resin. 

U.S. Pat. No. 6,590,004 [121] (by Crane Plastics Company, TimbeiTech) discloses a foamed fiber composite comprising 40-80% by weight of PVC or polypropylene, 20-60% by weight of cellulosic fiber, and additives such as stabilizer(s) in an amount of 1-10% per the polymer resin, lubricant(s) in an amount of 1-12% per the polymer resin, process aid(s) in an amount of 0.25-5% per the polymer resin. 

Radiation-induced discoloration of polypropylene is due mainly to the formation of colored radiolysis by-products from phenolic compounds included as processing aids in commercially availaUe formulations. Embrittlement is initiated through chain scission bringing about the reaction... 

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. 

Fiber finishes are normally added as lubricants or as antistats to the surface of fibers to facilitate fiber production and subsequent processing. Finishes are additives that may not achieve exactly what is intended. Low-molecular-weight mineral oils dissolve readily in polypropylene as do other materials added to the surface. It has been proposed that finishes may cause softening of the polymer surface [178], particularly at higher temperatures. Since polypropylene fibers are produced in colored form, the producer finish is not necessarily scoured off because it is for a dyeable fiber. The finish used by the fiber producer most frequently remains as part of the final product—for better or worse. Thus, the fiber finish must be considered not only as a processing aid but also as an additive. 

TPO materials are defined as compounds (mixtures) of various polyolefin polymers, semicrystalline thermoplastics, and amorphous elastomers. Most TPOs are composed of polypropylene and a copolymer of ethylene and propylene called ethylene—propylene rubber (EPR) [2]. A common rubber of this type is called ethylene propylene diene monomer rubber (EPDM), which has a small amount of a third monomer, a diene (two carbon-carbon double bonds in it). The diene monomer leaves a small amount of unsaturation in the polymer chain that can be used for sulfur cross-linking. Like most TPEs, TPO products are composed of hard and soft segments. TPO compounds include fillers, reinforcements, lubricants, heat stabilizers, antioxidants, UV stabilizers, colorants, and processing aids. They are characterized by high impact strength, low density, and good chemical resistance they are used when durability and reliability are primary concerns. 

Most of the current clarifiers are sorbitol derivatives. They include Great Lakes Clearlite NU 005, and Ciba s Irgaclear additives, some of which are now manufactured by Roquette in France, as well as NC-4 sorbitol acetal clarifiers supplied by Mitsui Toatsu Chemicals in Japan. One exception is Dover Chemical s Doverlube FL-599, a polyethylene glycol ester offered for clarifying polypropylene and also as a process aid for high impact polystyrene. 

All product contact surfaces are composed of polytetrafluoroethylene or polypropylene. Both polymers are highly chemically inert and have a high degree of compatibility with a variety of fluids. As with other processing aids, the user, who is most knowledgeable about the formulation of the product, is responsible for ensuring the compatibility of his/her formulation with LYOGUARD trays. 

Silicon-based polymers such as polydimethyl siloxanene (PDMS) have been used as polymer processing aids for many years. Dow Corning has developed ultra-high molecular weight PDMS additives that work as process aids in polyethylene and polypropylene. Because these materials solidify with the polymer, they reportedly... 

Acrawax C Prilled or Beaded is an effective lubricant, processing aid, slip additive and pigment disperssuit aid for most polymers Including ABS, PVC, polypropylene, nylon, acetal, polyethylene and thermoplastic polyester. 

In the case where a relatively large quantity of filler (talc) has to be incorporated into a polymer (e.g., polypropylene) it is often necessary to use a process aid/lubricant such as a zinc or calcium stearate. A quantification of the process aid can be achieved by the analysis of the sample for the metal by acid digestion-AAS. The stearate can be qualitatively detected by solvent extraction GC-MS. 

Foi example, nylon pile fabrics, exhibiting higher moisture regain, have different traction characteristics under wet and dry conditions than do polypropylene-based materials. Effects of artificial turf fabric constmction on shoe traction ate given in Table 2. Especially effective in aiding fabric surface uniformity is texturing of the pile ribbon, a process available for the two principal pile materials nylon and polypropylene. 

The research on the processes of mechanical destruction in deformed polypropylene (PP) melts was conducted with the aid of stable radical (tripentachlorphenylmethyl) consumption. There was defined the dependence of radical generation rate on shear rate. At low values y it is approximate to linear. 

Frothers are surfactants that contribute stability to the froth (foam) so that it will last long enough for solely mechanically-entrained particles to fall back into the pulp phase before the froth is skimmed. Frothers are frequently nonionic surfactants, such as cresol. Frothers may also aid the particle-bubble attachment process. Typical frothers include a variety of alcohols including a-terpineol (pine oil), cresol, polypropylene glycols, short-chain alcohols, and methylisobutylcarbinol (MIBC). 

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