Process polymer production applications

This chapter provides an overview of the most frequently applied numerical methods for the simulation of polymerization processes, that is, die calculation of the polymer microstructure as a function of monomer conversion and process conditions such as the temperature and initial concentrations. It is important to note that such simulations allow one to optimize the macroscopic polymer properties and to influence the polymer processability and final polymer product application range. Both deterministic and stochastic modeling techniques are discussed. In deterministic modeling techniques, time variation is seen as a continuous and predictable process, whereas in stochastic modeling techniques, a random-walk process is assumed instead. 

Most of the developments in polymer processing and product applications and... 

Fig. 1. General overview of a PHA production process. All PHA production processes consist of a fermentation and a recovery step, followed by polymer processing for specific applications. In many cases the fermentation is divided into two stages, a biomass production and a PHA accumulation stage (for further detail see text). Several methods for recovery of the material have been described, of which solvent-based and non-solvent-based recovery protocols are illustrated...

The best known aspect, and the first one to find commercialization in the direct fluorination area, was the fluorination of polymer surfaces. This Lagow-Margrave invention, trademarked Fluorokote, involved many types of polymeric materials in various forms e.g., polyethylene bottles, polypropylene objects, and rubber gloves. Polyethylene bottles are easily given fluorocarbon surfaces (>0.1 mm), and this has been commercialized. Air Products has at least 20 licenses for what is known as their Aeropak process and Union Carbide has a Linde Fluorination process as well. Applications in chemical, pharmaceutical, and cosmetic storage are widespread. 

The non-random two-liquid segment activity coefficient model is a recent development of Chen and Song at Aspen Technology, Inc., [1], It is derived from the polymer NRTL model of Chen [26], which in turn is developed from the original NRTL model of Renon and Prausznitz [27]. The NRTL-SAC model is proposed in support of pharmaceutical and fine chemicals process and product design, for the qualitative tasks of solvent selection and the first approximation of phase equilibrium behavior in vapour liquid and liquid systems, where dissolved or solid phase pharmaceutical solutes are present. The application of NRTL-SAC is demonstrated here with a case study on the active pharmaceutical intermediate Cimetidine, and the design of a suitable crystallization process. 

Applications of the combination of polymer-supported triarylphosphines (82) with carbon tetrachloride for the synthesis of peptides76 and acid chlorides,77 involving a simple filtration and evaporation process for product isolation, have been reported. 

Adhesive Transfer Processes. Many polymers, whether deliberately or accidentally, are adhesives, so that much of the adhesive industry can be regarded as a part of the mbber and plastics industry. However, there are several important material-transfer applications involving polymer products that are so critically dependent on controlled adhesion that they merit specific mention in that category. They include hot stamping foils, release coatings for pressure-sensitive adhesive products, photocopier materials, transfer coatings, and transfer printing of textiles. 

HDI and HDI prepolymers can be released to the atmosphere during spray applications of polymer paints containing residual amounts (0.5-1.0%) of monomeric HDI (Alexandersson et al. 1987 Hulse 1984 Karol and Hauth 1982). These substances could also be released to the atmosphere from waste streams from sites of HDI or polymer production. No information is available in the Toxic Chemical Release Inventory database on the amoimt of HDI released to the atmosphere from facihties that produce or process HDI because this compound is not included under SARA, Title 111, and therefore, is not among the chemicals that facilities are required to report (EPA 1995). There is also a potential for atmospheric release of HDI from hazardous waste sites however, no information was found on detections of HDI in air at any NPL or other Superfund hazardous waste sites (1996). Beeause of the relatively rapid reaction of HDI with hydroxyl radicals in the atmosphere an possible hydrolysis (see Seetion 5.3.2.1), significant atmospheric concentrations are not expeeted to oeeur exeept near emission sourees. 

Fig. 1. The key steps for the Phillips PPS process are (/) production of aqueous sodium sulfide from aqueous sodium hydrogen sulfide (or hydrogen sulfide) and aqueous sodium hydroxide (2) dehydration of the aqueous sodium sulfide and NMP feedstocks (5) polymerization of the dehydrated sulfur source with dichlorobenzene to yield a slurry of PPS and by-product sodium chloride in the solvent (4) polymer recovery (5) polymer washing for the removal of by-product salt and residual solvent (6) polymer drying (7) optional curing, depending on the application and (8) packaging.

URETHANE POLYMERS. The rapid formation of high molecular weight urethane polymers from liquid monomers, which occurs even at ambient temperature, is a unique feature of the polyaddition process, yielding products that range from cross-linked networks to linear fibers and elastomers. The enormous versatility of the polyaddition process allowed the manufacture of a myriad of products for a wide variety of applications. 

WATER SOLUBLE POLYMERS. Water-soluble polymers find application in a wide variety of areas that include polymers as food sources, plasma substitutes, and as diluents in medical prescriptions. Other areas of importance for water-soluble polymers include detergents, cosmetics, sewage treatment, stabilizing agents in the production of commodity plashes, rheology modifiers in the various processes for petroleum, textile, paper, and latex coatings production. The water-soluble polymers discussed in this article have significant commercial impact. 

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