Property modifiers, processing aids

Modifiers/compatibilizers Ethylene/methyl acrylate copolymer  

Description (EMAC) Used as an impact modifier and compatibilizer good tie-layer in coextrusion, with broad temperature range translucent/clear colour  

Description High molecular weight acrylic copolymers, as white free-flowing powders, to improve processability of PVC compounds lubricant grades reduce adherence to melt to processing equipment  

Description Good resistance to extraction and migration polyesters, based on adipic acid liquid  

Description DOP is the most widely used plasticizer other grades are for special purposes, heat-resistant cable, etc.  

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Additives for Plastics Handbook Property modifiers, processing aids... 

The dynamic mechanical behavior of most homogeneous and heterogeneous solid and molten polymeric systems or composite formulations can be determined by DMA. These polymeric systems may contain chemical additives, including fillers, reinforcements, stabilizers, plasticizers, flame retardants, impact modifiers, processing aids, and other chemical additives, which are added to the polymeric system to impart specific functional properties and which could affect the process-ability and performance. 

Raw Materials. PVC is inherently a hard and brittle material and very sensitive to heat it thus must be modified with a variety of plasticizers, stabilizers, and other processing aids to form heat-stable flexible or semiflexible products or with lesser amounts of these processing aids for the manufacture of rigid products (see Vinyl polymers, vinyl chloride polymers). Plasticizer levels used to produce the desired softness and flexibihty in a finished product vary between 25 parts per hundred (pph) parts of PVC for flooring products to about 80—100 pph for apparel products (245). Numerous plasticizers (qv) are commercially available for PVC, although dioctyl phthalate (DOP) is by far the most widely used in industrial appHcations due to its excellent properties and low cost. For example, phosphates provide improved flame resistance, adipate esters enhance low temperature flexibihty, polymeric plasticizers such as glycol adipates and azelates improve the migration resistance, and phthalate esters provide compatibiUty and flexibihty (245). 

Demand for the different classes of polymer additives varies by resin. Modifiers and processing aids rely heavily on PVC while the property extenders are primarily used in non-PVC resins. PVC is by far the largest consuming resin for polymer additives (excluding fillers), accounting for some 80% of the world-wide volume or 60 % in total value. Polyolefins are a distant second accounting for 8% and 17%, respectively [36]. 

Formulation of dry powders for inhalation must rely on a very short list of excipients to fulfill the customary roles of diluent, stabilizer, solubilizer, processing aid, and property modifier (e.g., flow enhancer). In the United States, only a few materials are approved for use in inhalation products, and of those (e.g., propellants, surfactants) many are of little help in dry powder formulation. 

It should be noted that constituents in terms of plastics could include residues (from the polymerisation process), additives (ingredients added to enhance or modify certain properties), processing aids (ingredients added or used to assist in a fabrication or conversion process, e.g. mould release agents, lubricants), and master batch constituents (if a master batch is used). 

These constituents may include additives antistatic additives, UV absorbers, antislip additives, slip additives, colourants, opacifiers, plasticisers, stabilisers, antioxidants, etc., which may be added at the compounding stage to provide specific or modified properties. However, other constituents may be present from the polymerisation and/or the converting processes. The polymerisation process may involve residues and processing aids. Residues (constituents which may remain from the polymerisation process) may include monomer(s), solvents, accelerators, catalysts, initiators, etc. Processing aids are additional substances to aid processing or restrain undesirable effects, e.g. antioxidants. 

The possibilities for copolymers with specialized performance characteristics depend on the ability to effect copolymerization with the other monomer. To date efforts to effect copolymerization with such monomers as styrene and butadiene have been unsuccessful (r2=35 vs. rj =0.067 for styrene, and r2=8.8 vs. r =0.035 for butadiene). The possibilities nevertheless exist for modifying the basic polymer to effect such desirable properties as cross-linking, improvement in impact resistance, compatibility with processing aid modifiers, and UV stability. 

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