Polycaprolactam

Only the last factor is a little tricky it is also different with and without additives. With no additive, polycaprolactam can be represented A BABAB. . . ABAB, where the A and B are acid and base groups, respectively, and those marked with the asterisk are those analyzed. Thus every molecule has one of each. In this case, then, we use the average of 12.0 and 11.6 as the end group concentration, and unity as the number of ends of each kind to obtain... 

The molecular weights obtained by this method are averages. This is particularly evident from the situations where additives are present. In these cases, two different kinds of chains result, with those terminated by the same end group being stunted in growth compared to the normal polycaprolactam. Yet it is the total weight of polymer and the total number of ends that are... 

The more familiar source-based names for these polymers are poly(phenylene oxide) (1), poly(ethylene terephthalate) (2), and polycaprolactam (3). 

Nylon, an aUphatic polyamide, was introduced as a commercial tire cord in 1947 and grew in usage to - 5.4 billion kg/yr (- 2 billion Ib/yr) in the 1990s (10,11). Nylon-reinforced tires use nylon-6 poljmier (polycaprolactam) fibers as well as nylon-6,6 (poly(hexamethylenediainine adipamide)) fibers. Nylon tire cords are characterized by extremely good fatigue resistance in compression and good adhesion to most mbber compounds with simple RFL adhesives. 

An MAI composed of polycaprolactam was investigated on its thermal decomposition behavior to develop easy decomposable polymers, the addition of oxidative deterioration was needed [72]. 

In semi-cristalline polymers, rate-enhancement under stress has been frequently observed, e.g. in UV-photooxidation of Kapron, natural silk [80], polycaprolactam and polyethylene terephthalate [81]. Quantitative interpretation is, however, difficult in these systems although the overall rate is determined by the level of applied stress, other stress-dependent factors like the rate of oxygen diffusion or change in polymer morphology could occur concurrently and supersede the elementary molecular steps [82, 83], Similar experiments in the fluid state showed unequivocally that flow-induced stresses can accelerate several types of reactions, the best studied being the hydrolysis of DNA [84] and of polyacrylamide [85]. In these examples, hydrolysis involves breaking of the ester O —PO and the amide N —CO bonds. The tensile stress stretches the chain, and therefore, facilitates the... 

CL must be very carefully purified to exclude small concentrations of (1) ferric ions which would catalyze die thermal oxidative degradation of polycaprolactam and (2) aldehydes and ketones which would markedly increase oxidizability of CL. The impurities in CL may retard die rate of CL polymerization as well as having a harmful effect on die properties of die polymer fiber. In die vacuum depolymerization of nylon-6, a catalyst must be used because in die absence of a catalyst by-products such as cyclic olefins and nitrides may form, which affects the quality of die CL obtained.1... 

See also PBT degradation structure and properties of, 44-46 synthesis of, 106, 191 Polycaprolactam (PCA), 530, 541 Poly(e-caprolactone) (CAPA, PCL), 28, 42, 86. See also PCL degradation OH-terminated, 98-99 Polycaprolactones, 213 Poly(carbo[dimethyl]silane)s, 450, 451 Polycarbonate glycols, 207 Polycarbonate-polysulfone block copolymer, 360 Polycarbonates, 213 chemical structure of, 5 Polycarbosilanes, 450-456 Poly(chlorocarbosilanes), 454 Polycondensations, 57, 100 Poly(l,4-cyclohexylenedimethylene terephthalate) (PCT), 25 Polydimethyl siloxanes, 4 Poly(dioxanone) (PDO), 27 Poly (4,4 -dipheny lpheny lpho sphine oxide) (PAPO), 347 Polydispersity, 57 Polydispersity index, 444 Poly(D-lactic acid) (PDLA), 41 Poly(DL-lactic acid) (PDLLA), 42 Polyester amides, 18 Polyester-based networks, 58-60 Polyester carbonates, 18 Polyester-ether block copolymers, 20 Polyester-ethers, 26... 

The other entries in Table 13.2 show that heat removal is not a problem for most ring-opening and condensation polymerizations. Polycaprolactam (also called Nylon 6) is an addition polymer, but with rather similar bond energies for the monomer and the polymer. The reaction exotherm is small enough that large parts are made by essentially adiabatic reaction in a mold. An equilibrium between monomer and polymer does exist for polycaprolactam, but it occurs at commercially acceptable molecular weights. 

PatentNumber US 5869654 A 19990209 PROCESS FOR DEPOLYMERISING POLYCAPROLACTAM PROCESSING WASTE TO FORM CAPROLACTAM... 

The polycaprolactam waste is contacted with superheated steam in the absence of added catalyst at a temperature of about 250 to 400C and a pressure in the range of about 1.5 to 100 atm. and substantially less than the saturated vapour pressure of water at the temperature at which a caprolactam-containing vapour stream is formed. The resulting caprolactam may then be used in the production of engineered resins and fibres. 

Like imines, some oximes are known to undergo metabolic hydrolysis by a nonenzymatic mechanism. Cyclohexanone oxime (11.69), an intermediate in the synthesis of polycaprolactam or Nylon-6, is a good example with which to begin our discussion. Following administration to male rats by various routes, cyclohexanone oxime undergoes rapid metabolism, and only trace amounts of the parent compound can be recovered in the urine [104], Although cyclohexanone (11.70) represented a small fraction of the urinary metabolites, most of the dose was recovered as glucuronides of cyclohexa-nol (11.71) and of cis- and /ran.v-cyclohexanc-1,2-diol. 

Uses. Monomer for manufacture of polycaprolactam (Nylon 6) used in carpets, textiles, clothing, and tires... 

Monomers may be in the solid, liquid or gaseous state. In the first phase, blending and comminution is generally carried out to reduce inhomogeneities. For the same reason, polymer particle size can also influence the reaction. For example, in the grafting of vinyl chloride on polycaprolactam, the Cl content of the resultant polymer was 3.71 % and 2.16% when 0.05-0.09 mm and 0.4-0.63 mm diameter polycaprolactam particles were employed (31). To obtain polymer in the desired powder form, the polymer was pulverized and selectively precipitated. 

Grohn and Vasiliu-Oprea (18,31,32,41) studied the grafting of several vinyl monomers on polyamide, mainly polycaprolactam. [Their work was summarized in the Simionescu and Vasiliu-Oprea book (73).] In each case, the polymer was first purified by extraction, dissolution and reprecipitation. The grinding was performed at 0.42 fraction packing and by using 16 mm diameter steel balls, at an amplitude of 1.75 mm and at 1420 rpm. With vinyl chloride the air was eliminated from the reaction jar and the monomer was introduced at up to two... 

The grafting of acrylonitrile and styrene on polycaprolactam was carried out in the liquid state (18,31). The more important parameters were monomer concentration and the milling time. In order to separate the effect of total liquid and of monomer concentration, the reactions were also conducted in solution. 

Fig. 7. Polymerization of vinyl chloride by vibromilling polycaprolactam. Composition at various millings /) total PVC in the interpolymer, 2) graft PVC 3) free PVC (13)...

Table 6. Polymerization of vinyl monomers by vibromilling polycaprolactam. Composition...

Baramboim and coworkers (93-95, 95 bis) obtained graft copolymers based on polyamides. The extrusion of a polypropylene polycaprolactam mixture at 200-210° C changed the polypropylene molecular weight and formed a block and graft copolymer of linear and three dimensional structure. Investigations showed the radical nature of the process and that the amount of the resulting copolymer was proportional to the intensity of mechanical shear. 

Nylon 6 (polycaprolactam, Perlon) is the most widely used monadic nylon. It has a lower melting point (225 C) than nylon 5 (270 0. which is not available commercially. As shown in Table 14.2 the coefficient of linear expansion of nylon 6 is the same as that of nylon 66. However, its heat deflection temperature (80 ) is slightly higher than that of nylon 66 (75 C). Nylon 7 (polyenantholactam) has a slightly higher Tm (227 0. a slightly greater flexibility, and a lower water absorption than nylon 6. 

The ring opening polymerization of cyclic monomers that yield thermoplastic polymers of interest in composite processing is reviewed. In addition, the chemistry, kinetics, and rheology of the ring opening polymerization of caprolactam to nylon 6 are presented. Finally, the rheo-kinetics modelsfor polycaprolactam are applied to the composite process of reaction injection pultrusion. 

The rheokinetics of polycaprolactam polymerizing in the monomer shows that below 50 percent conversion, the relative complex viscosity versus conversion of the nylon 6 homopolymerization is defined by the phenomenological equation ri / t]Q = exp(19.6 X), where // is the complex viscosity of nylon 6 anionically polymerizing in its monomer, 0 is the viscosity of caprolactam monomer, and X is fractional conversion. 

EXAMPLE 4.5 Empirical Determination of the Mark-Houwink Coefficients for a Polymer Solution. The molecular weights of various polycaprolactam preparations were determined by end-group analysis (see Example 3.2) intrinsic viscosities of the various fractions in m-cresol were measured at 25°C. The following values are representative of the results obtained (Reim-schussel and Dege 1971) ... 

According to the 1981-83 National Occupational Exposure Survey (NOES, 1997), approximately 25 000 workers in the United States were potentially exposed to caprolactam (see General Remarks). Occupational exposures to caprolactam may occur in the manufacture of the chemical and of polycaprolactam (nylon 6) fibres and resins. 

Acrylonitrile is reported to react in a mixture of 60% aqueous zinc chloride solution (450 ml) and 36% aqueous hydrochloric add (50 ml) containing dissolved polycaprolactam to which f-butyl peracetate, dissolved in the above mentioned salt solution, was added (5). Thermal initiation is also reported in dimethyl formamide and m-cresol solution (<4). 

Potassium hydroxide absorbed into powdered polycaprolactam and heated with ethylene oxide gas in chlorobenzene at 80° C for 7 hrs is the process claimed... 

Acrylonitrile and other olefinic monomers can be grafted on polycaprolactam by an indirect method in which the polyamide powder is first submitted to nitro-sation with dinitrogen trioxide and then bulk polymerized at 60° C (12). 

Instead of monomers, polymers in solution can be grafted on Nylon structures. Aqueous solution of poly(acrylic add) is used for impregnation of polyamide fabrics which is subsequently dried during 1 to 5hrs at 80-150° C after which cure is carried out for 15 to 60 min at 150-218° C (99). A copolymer of styrene-maleic anhydride is said to be grafted on polycaprolactam by heating at 230° C at a pressure of 25 kg/cm2 (100). 

Other polymers like polypropylene or polystyrene modified by maleic anhydride or maleamide, with the add groups converted to amide, ester or ester chloride and then reacted on Nylon fibers, have been claimed in a Japanese patent (101). Two patents report grafting of olefinic polymers on polycaprolactam (102,103). Grafting of polysiloxanes on polyamides can be induced by X-rays (104). 

On the other hand, chemicals might be chosen as agents for generation of active centers in the polymeric backbone and grafting of monomer in the vapor phase. Ammonium persulfate and styrene (189), acrylic acid (190), butyl acrylate (191), potassium persulfate and n-butyl maleate or 2-ethyl hexyl acrylate (55,134) and ammonium ceric nitrate and methacrylic add (192) are examples of this method. Benzoyl peroxide deposited on polycaprolactam fibers initiates the grafting of styrene in vapor phase (193). 

Amorphous polycaprolactam/polyvinylchloride10) Polyvinylchloride/poly(acrylonitrile-co-butadiene) 11 . 

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