Polyamides properties

Table 3.6 Examples of the effect of glass beads on polyamide properties...

Figure 4.51(b)-(d) display in a simplified manner the evolution of basic polyamide properties for various neat grades. 

Gao J, Wang X, Li X et al. (2006) Prediction of polyamide properties using quantum-chemical methods and BP artificial neural networks. J Mol Model 12 513-520... 

Other Modifications of Polymer Structure. In order to more fully determine the effects of structural change upon polyamide OPV, several other modifications of the basic aliphatic-aromatic backbone were performed. One simple modification is to reverse the direction of the amide linkage. The data in Table II indicate that for at least the shorter chain polyisophthalamides, amide reversal has no measurable effect upon the OPV at either 0% or 80% RH. It is surprising to note that the amide direction does not seem to affect either density or Tg in addition to OPV. Furthermore, Morgan and Kwolek reported that the amide direction had little, if any, effect upon the melting points on aliphatic terephthalamides and their analogs (21). It is due to the indifference of polyamide properties to amide direction that data for MPD-14 is included in Figures 3 and 5. 

Table II. Effect of Amide Reversal on Polyamide Properties...

Features Curing agent for maintenance and marine coatings, overprint varnishes, masonry and pool coatings, adhesives, caulks, grouts flexibilizer for thermoplastic polyamides Properties Gardner < 9 cotor dear appearance dens. 8.1 Ib/gal vise. 150,000 poise amine no. 85-95 flash pt. (CC) > 160 C 100% solids Epikure 3100-ET-60 [Resolution Perl. Prods.]... 

A different cardo group like xanthene has been used to improve the solubility of PAs [14], Ma et al. studied the effect of the xanthene group on the polyamide properties. They prepared the diacid chloride of 9,9-( i5[4-(4-chloroformylphenoxy)phenyl]... 

In general, in CL polymerization, an equivalent concentration of activator (A) (N-acyl lactam or N-carbamoyl lactam) and initiator (I), in terms of its functional groups, is the best compromise among polymerization rate, overall conversion, degree of polymerization, high polymer yield, and polyamide properties (see Section 4.14.10.3). 

Uses Leveling agent for dyeing polyamide Properties Liq. 60% cone. 

Polyamides from diamines and dibasic acids. The polyamides formed from abphatic diamines (ethylene- to decamethylene-diamine) and abphatic dibasic acids (oxabc to sebacic acid) possess the unusual property of forming strong fibres. By suitable treatment, the fibres may be obtained quite elastic and tough, and retain a high wet strength. These prpperties render them important from the commercial point of view polyamides of this type are cabed nylons The Nylon of commerce (a 66 Nylon, named after number of carbon atoms in the two components) is prepared by heating adipic acid and hexamethylenediamine in an autoclave ... 

The leader of DuPont s effort was Wallace H Carothers who reasoned that he could reproduce the properties of silk by constructing a polymer chain held together as is silk by amide bonds The neces sary amide bonds were formed by heating a dicar boxylic acid with a diamine Hexanedioic acid adipic acid) and 1 6 hexanediamme hexamethylenedi-amine) react to give a salt that when heated gives a polyamide called nylon 66 The amide bonds form by a condensation reaction and nylon 66 is an example of a condensation polymer... 

Properties Polyamide Poly(amide- imide), unfilled... 

The various mechanical properties of polyamides may be traced in many instances to the possibility of intermolecular hydrogen bonding between the polymer molecules and to the relatively stiff chains these substances possess. The latter, in turn, may be understood by considering still another equilibrium, this one among resonance structures along the chain backbone ... 

The recycling of engineering thermoplastics such as polyamides, ABS, and PTEE have been discussed (50). Property degradation as a result of use, recovery, and recycling is a concern. 

In the area of moleculady designed hot-melt adhesives, the most widely used resins are the polyamides (qv), formed upon reaction of a diamine and a dimer acid. Dimer acids (qv) are obtained from the Diels-Alder reaction of unsaturated fatty acids. Linoleic acid is an example. Judicious selection of diamine and diacid leads to a wide range of adhesive properties. Typical shear characteristics are in the range of thousands of kilopascals and are dependent upon temperature. Although hot-melt adhesives normally become quite brittle below the glass-transition temperature, these materials can often attain physical properties that approach those of a stmctural adhesive. These properties severely degrade as the material becomes Hquid above the melt temperature. 

Amidation. Heating of the diammonium salt or reaction of the dimethyl ester with concentrated ammonium hydroxide gives adipamide [628-94-4] mp 228°C, which is relatively insoluble in cold water. Substituted amides are readily formed when amines are used. The most industrially significant reaction of adipic acid is its reaction with diamines, specifically 1,6-hexanediamine. A water-soluble polymeric salt is formed initially upon mixing solutions of the two materials then hea ting with removal of water produces the polyamide, nylon-6,6. This reaction has been studied extensively, and the hterature contains hundreds of references to it and to polyamide product properties (31). 

Other elastomeric-type fibers iaclude the biconstituents, which usually combine a polyamide or polyester with a segmented polyurethane-based fiber. These two constituents ate melt-extmded simultaneously through the same spinneret hole and may be arranged either side by side or ia an eccentric sheath—cote configuration. As these fibers ate drawn, a differential shrinkage of the two components develops to produce a hehcal fiber configuration with elastic properties. An appHed tensile force pulls out the helix and is resisted by the elastomeric component. Kanebo Ltd. has iatroduced a nylon—spandex sheath—cote biconstituent fiber for hosiery with the trade name Sidetia (6). 

When drawdown is high, the film may be uniaxially oriented and the properties of the final film isotropic. In the manufacture of strapping tape this effect is accentuated. If the cast or quenched film is to be used to feed an orientation tine, additional attention must be given to the amorphous—crystalline nature of the film ia the draw processes so that maximum strength can be achieved and uniform gauge and optical quality maintained. Slot casting is used for the orientation of these resins, polyesters, polyamides, and a variety of others. 

BiaxiaHy oriented films have excellent tensile strength properties and good tear and impact properties. They are especially well regarded for their brilliance and clarity. Essentially all poly(ethylene terephthalate) film is biaxiaHy oriented, and more than 80% of polypropylene film is biaxiaHy oriented. Polystyrene film is oriented, and a lesser amount of polyethylene, polyamide, poly(vinyl chloride), and other polymers are so processed. Some of the specialty films, like polyimides (qv), are also oriented. 

Dyes, application and evaluation). Foi dyeing fibei blends such as viscose—polyamide, polyamide—Spandex, oi polyestei—cotton, only compatible FWAs may be used that do not inteifeie with one another oi have any detrimental effect on fastness properties. 

In 1954 the surface fluorination of polyethylene sheets by using a soHd CO2 cooled heat sink was patented (44). Later patents covered the fluorination of PVC (45) and polyethylene bottles (46). Studies of surface fluorination of polymer films have been reported (47). The fluorination of polyethylene powder was described (48) as a fiery intense reaction, which was finally controlled by dilution with an inert gas at reduced pressures. Direct fluorination of polymers was achieved in 1970 (8,49). More recently, surface fluorinations of poly(vinyl fluoride), polycarbonates, polystyrene, and poly(methyl methacrylate), and the surface fluorination of containers have been described (50,51). Partially fluorinated poly(ethylene terephthalate) and polyamides such as nylon have excellent soil release properties as well as high wettabiUty (52,53). The most advanced direct fluorination technology in the area of single-compound synthesis and synthesis of high performance fluids is currently practiced by 3M Co. of St. Paul, Minnesota, and by Exfluor Research Corp. of Austin, Texas. 

Nylon. Nylon is the designation for a family of thermoplastic polyamide materials which in film form are moderate-oxygen barriers. The gas-barrier properties are equal to odor and flavor barrier properties important in food appHcations. Nylon films are usually tough and thermoform able, but are only fain moisture barriers (see Polyamides). 

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