Plasticizers flexible, performance

A copolymer of ethylene and vinyl acetate which processes like a plastic and performs like a rubber. The copolymer, of which there are various grades, is similar to rubber in softness and flexibility but can be injection moulded without vulcanisation. 

The future of plasticizers and plasticized PVC is tied very closely to the future of phthalates. The top performing and lowest cost plasticizers are the GP phthalate esters, and of all the thousands of nonphthalate ideas proposed, no products to date have been developed that equal the attributes offered with phthalates. As formulations change to nonphthalate systems, the flexible PVC products obtained with those alternatives will not perform as well and will often be more expensive. Thus with poorer performing, more expensive plasticized flexible PVC materials, the opportunities for inter-material substitution to replace these products with other flexible polymer systems will increase. 

Plasticizers may perform the following useful functions in adhesives based on thermoplastic rubbers decrease hardness and modulus, eliminate drawing, enhance pressure-sensitive tack, improve low temperature flexibility, reduce melt and solution viscosity, decrease cohesive strength or increase plasticity if desired, and substantially lower raw material costs. The... 

Attempts have been made to perform thermal retorting ia a gas barrier flexible pouch or tray. The retort pouch, under development for many years, has a higher surface-to-volume ratio than a can and employs a heat seal rather than a mechanical closure. Similarly, plastic retort trays have higher surface-to-volume ratios and are usually heat seal closed. Plastic cans iatended for microwave reheating are composed of bodies fabricated from multilayer plastic including a high oxygen barrier material, plus double-seam aluminum closures. 

In a flexible PVC compound, ingredients in the recipe are chosen based on cost and/or thein contribution to physical and other properties and performance. Typical ingredients (16,17) are stabilizers, fillers, plasticizers, colorants, and lubricants. 

Low Temperature Performance. The abihty of plasticized PVC to remain flexible at low temperatures is of great importance in certain apphcations, eg, external tarpaulins or underground cables. Eor this property the choice of the acid constituent of the plasticizer ester is also important. The linear aUphatic adipic, sebacic, and azeleic acids give excellent low temperature flexibiUty compared to the corresponding phthalates and trimeUitates (Pig. 3). 

Electrical Applications. Plastics are used for electrical insulation, conduit and enclosures, lighting fixtures, and mechanical devices. The most widely used plastic for wire and cable insulation is flexible, plasticized PVC, which constitutes well over half the market in insulating wires for buildings, automobiles, appHances, and power and control lines. Polyethylene is also a factor. Higher performance plastics such as nylon and fluoropolymers also play a smaller role in this area. 

In 1990 the majority of U.S. PCB production resulted from subtractive or print-and-etch processing additive processes were less than 6% of the total multilayer boards accounted for 55.8%. The ratio of rigid to flexible surface areas plated is about 15 1. High performance plastics including polyimide. Teflon, and modified epoxy comprised 6% of the market ( 324 million) flexible circuits were 6.6% ( 360 million) (42). 

Polymer thick films also perform conductor, resistor, and dielectric functions, but here the polymeric resias remain an iategral part after cuting. Owiag to the relatively low (120—165°C) processiag temperatures, both plastic and ceramic substrates can be used, lea ding to overall low costs ia materials and fabrication. A common conductive composition for flexible membrane switches ia touch keyboards uses fine silver particles ia a thermoplastic or thermoset polymeric biader. 

These materials also have high thermal and oxidative stabiHty. Flexible segments such as amide siloxane can be incorporated into the imide-based stmcture for hot melt or injection appHcations. General Electric (GE) and Hoechst-Celanese are suppHers of these high performance plastics. 

In some cases, plasticization of a PSA may be detrimental to its performance. A well-known example is the deterioration of the performance of an adhesive applied to plasticized PVC. Migration of the plasticizer from the flexible vinyl into the PSA often softens the adhesive to the point where it fails cohesively from the vinyl, leaving sticky residue behind during removal of the adhesive-coated article from the substrate. One way to address this detrimental effect of plasticizer migration is to formulate an already plasticized PSA, perhaps because a better balance exists between the plasticizer in the PVC substrate and the PSA in contact with it [101]. 

Plastic also refers to a material that has a physical characteristic such as plasticity and toughness. The general term commodity plastic, engineering plastic, advanced plastic, advanced reinforced plastic, or advanced plastic composite is used to indicate different performance materials. These terms and others will be reviewed latter in this chapter. Plastics are made into specialty products that have developed into major markets. An example is plastic foams that can provide flexibility to rigidity as well as other desired properties (heat and electrical insulation, toughness, filtration, etc.). 

Plastics offer the opportunity to optimize RP design by focusing on material composition in conjunction with reinforcement orientation, as well as product structural geometry. This interrelation affects processing methods, product performances, and costs. This action also gives the designer great flexibility and provides freedom not possible with... 

A route to compatibility involving ionomers has been described recently by Eisenberg and coworkers [250-252]. The use of ionic interactions between different polymer chains to produce new materials has gained tremendous importance. Choudhury et al. [60] reported compatibilization of NR-polyolefin blends with the use of ionomers (S-EPDM). Blending with thermoplastics and elastomers could enhance the properties of MPR. The compatibility of copolyester TPE, TPU, flexible PVC, with MPR in aU proportions, enables one to blend any combination of these plastics with MPR to cost performance balance. Myrick has reported on the effect of blending MPR with various combinations and proportions of these plastics and provided a general guideline for property enhancement [253]. 

The Waters system uses a plastic cartridge which is inserted into a device (the Z-module) that subjects the column to radial compression, ie pressure is applied along the radial axis of the column tube. The flexible wall of the column then moulds itself into the voids that are present in the wall regions of the column. This method is claimed to produce an improvement in the packed bed structure, better column performance and longer useful column life. 

There is currently great commercial interest in plastic alternatives to conventional silicon-based components in electronic devices. Polymeric architectures offer flexible, low-cost, processable materials for this lucrative global market, and can be designed with more emphasis on device performance. The principal goals of improved band filling, dimensionality and new conductance mechanisms remain the same, and provide a subtly different challenge to the materials chemist. 

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