Nylon, uses

E.I. Du Pont de Nemours and Company (1984) Preparation of salt solution useful for making nylon. US 4,442,260. 

Both processes rely on a fast flow system and the rapid quenching of product gases yields of up to 90% can be attained. It is salutory to note that US production of this highly toxic compound is 600000 tonnes pa (1992) and world production exceeds one million tonnes pa. Of this, 41% is used to manufacture adiponitrile for nylon and 28% for acrylic plastics ... 

DSM and Allied Signal have developed carpet identification equipment that can identify specific plastics. Particularly carpet made of nylon 6 (or nylon 66) fibres are separated, cut into pieces, isolated, and converted by polycondensation into their monomeric components. The monomers can then be reused in the production of nylon. DSM and Allied Signal opened the world s first large scale carpet recycling plant in Augusta, Georgia, US in November 1999. This plant has a capacity of 90,000 tpa nylon 6 carpet waste (109). 

Evergreen Nylon Recycling, a DSM/AlliedSignal joint venture, opened in November 1999. The plant will eonvert over 90,000 t/y of nylon 6 earpet waste into the raw material for nylon, caprolaetam. At the moment 450,000 tonnes of nylon 6 earpet waste is transported to US landfills each year. A fifth of this will be reeyeled in the new plant. The 45,000 tonnes of eaprolaetam that Evergreen Nylon Reeyeling will produee every year ean be used to make nylon 6 of the same quality and with the same properties as virgin nylon 6. 

This fall, the closed-loop Evergreen Nylon Recycling plant will start up in the US, a joint venture of DSM Chemicals North America and AlliedSignal. The facility will recover 45,000 m.t./year of caprolactam by depolymerising the fibres from 100,000 m.t./year of discarded nylon-6 carpets. Meanwhile in Germany, Lurgi is building the Polyamid 2000 AG facility. It will process 120,000 m.t./year of carpet waste and recover 10,000 m.t./ year of caprolactam from nylon-6 carpets and 13,000 m.t./ year of nylon-6-6 from nylon-6-6 carpets. 

The nylon 66 molecule shown in Fig, 1,11 is a thermoplastic polymer, created by the step growth polymerization of hexamine and adipic acid. The majority of commercial polymers are thermoplastics, which permits us to readily mold them to many useful shapes. 

Anionic ring opening polymerization of lactams to generate polyamides has been studied quite extensively by Sebenda [8-10], Sekiguchi [11], and Wichterle [12-13], among others, in academia, and by Gabbert and Hedrick [14] and by us [23-25] in industry. By far, caprolactam is the most studied lactam and the nylon 6 prepared by this route compares favorably in properties with that prepared by conventional hydrolytic polymerization. 

Based on knowledge of relative properties and costs, it appeared to us that Celcon had some advantages to offer in the application. We quickly learned that people making tubing from nylon were extruding at rates up to 150 feet per minute. At the time, our company had very little experience with the extrusion properties of Celcon and we learned that under conditions which were being used... 

Fig. 1. US total sales and captive use of selected thermoplastic resins by major market for 2001. Major market volumes are derived from plastic resins sales and captive use data as compiled by VERIS Consulting, LLC and reported by the American Plastics Council s Plastic Industry Producers Statistics Group. Selected thermoplastics are low-density polyethylene, linear low-density polyethylene, high-density polyethylene, polypropylene, nylon, polyvinyl chloride, thermoplastic polyester, engineering resins, acrylonitrile-butadiene-styrene, styrene-acrylonitrile, other styrenics, polystyrene, and styrene butadiene latexes. (Data from ref. 25.)...

The Polyamid 2000 plant in Premnitz, Germany is another nylon 6 carpet recycling facility. For an investment of US 200 million in 2000, the plant was designed to process 264 million pounds per year of carpet and produce 20 million lb/yr of nylon 6 plus 25 million pounds of nylon 6,6 and other engineering plastics271. 

Chemical manufacturing and petroleum refining have enriched our lives. Few individuals in the developed world stop to realize how the chemical industry has improved every minute of their day. The benefits of the industries are apparent from the time our plastic alarm clock tells us to wake up from a pleasant sleep on our polyester sheets and our polyurethane foam mattresses. As our feet touch the nylon carpet, we walk a few steps to turn on a phenolic light switch that allows electrical current to safely pass through polyvinyl chloride insulated wires. At the bathroom sink, we wash our face in chemically sanitized water using a chemically produced soap. 

Polymers are very large molecules made up of repeating units. A majority of the compounds produced by the chemical industry are ultimately used to prepare polymers. These human-made or synthetic polymers are the plastics (polyethylene, polystyrene), the adhesives (epoxy glue), the paints (acrylics), and the fibers (polyester, nylon) that we encounter many times each day. It is difficult to picture our lives without these materials. In addition to these synthetic polymers, natural polymers such as wood, rubber, cotton, and wool are all around us. And, of course, life itself depends on polymers such as carbohydrates, proteins, and DNA. This chapter discusses synthetic polymers. Naturally occurring polymers are presented in Chapters 25, 26, and 27. 

Chorvath I et al. (2002) Thermoplastic elastomer compositions containing silicone rubber and nylon resins and the dynamically vulcanizing method. US Patent... 

Detoflex Flexible Cord Explosive. Deraflex is the cord version of DuPont Detasheet (qv) and exhibits the same properties of flexibility, insensitivity to shock, elasticity and resistance to moisture as die sheet material. It meets the requirements of US Military Specification (Ref 1). The cord is available in diameters from 0.084" to 0.665 both in uncountered and nylon countered forms. It is particularly useful in underwater demolition work (Refs 2 3)... 

Polyester fibers, similar to polyamide fibers, represent another important family of fiber. Polyester fiber was discovered in England in 1941 and commercialized in 1950. Two common trade names of polyester are Dacron in the US and Terylene in the UK. The term polyester fiber represents a family of fibers made of polyethylene terephthalate. Dimethyl terephthalate is reacted with ethylene glycol in the presence of a catalyst, antimony oxide, to produce polyethylene terephthalate or polyester. The chain repeat structure of PET is given in Fig. 4.6. Although polyesters can be both thermosetting and thermoplastic, the term polyester has become synonymous with PET. Note that the PET chain structure is different from the simpler structure of nylon or polyethylene. In PET, the aromatic ring and its associated C-C bonds provide a rigidity to the structure. The polyester structure is also bulkier than that of nylon or polyethylene. These factors make polyester less flexible than nylon and polyethylene, and the crystallization rate of PET slower than that of nylon or polyethylene. Thus, when polyester is cooled from the melt, an appreciable amount of crystallization does not result. 

Let us consider these two approaches in some detail. Recall that stretching polymers at temperatures below their melting point improves their stiffness and strength. Techniques involving some stretching are used commercially for nylon, polyester, and polypropylene fibers (as well as some polymer films) (see Section... 

Moreover, the published ESR spectra of the mechano-radicals of other polymers, for example Nylon 66 (i 7) elastomers (23, 61, 62) appears considerably asymmetric. It seems to us that the asymmetric patterns surest contamination with peroxy radicals, which would be formed by reaction of the mechano-radicals witii oxygen. Ex-... 

The membrane material strongly influences the effect of US energy on filtration. Water permeation through a polyacrylonitrile (PAN) membrane from a dextran [96], that of NaCI through a nylon membrane coated with amphiphiles [97], the transport of organic compounds aoross a polymer membrane suspension, and that of hydrocortizone and benzoio aoid through a cellulose membrane and poly-dimethylsiloxane membrane, respeotively [98], illustrate the influence of the membrane material on the type of particles it can retain optimally. 

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