Dicarboxylic polyamide

The PEBA are produced by a aiolten state polycondensation reaction of a dicarboxylic polyamide and a polyether diol. The reaction of the rigid polyamide (hard) segments and amorphous polyether (soft) segments in the presence of heat, vacuum and catalyst yields the polyether block amide with the general formula shown below. 

The dicarboxylic polyamide, or diacid, is obtained from the reaction of a polyamide monomer with a chain limiter. The molecular weight of the diacid is regulated by the amount of chain limiter present during the reaction. Several types of polyamides can be selected for production of the PEBA among these are ... 

Nylon A class of synthetic fibres and plastics, polyamides. Manufactured by condensation polymerization of ct, oj-aminomonocarboxylic acids or of aliphatic diamines with aliphatic dicarboxylic acids. Also rormed specifically, e.g. from caprolactam. The different Nylons are identified by reference to the carbon numbers of the diacid and diamine (e.g. Nylon 66 is from hexamethylene diamine and adipic acid). Thermoplastic materials with high m.p., insolubility, toughness, impact resistance, low friction. Used in monofilaments, textiles, cables, insulation and in packing materials. U.S. production 1983 11 megatonnes. 

HOaQCHjlfiCOiH, CSH14O4. Important dicarboxylic acid obtained by oxidizing ricino-leic acid (from castor oil) also obtained by oxidation of cyclo-octene or cyclo-octadiene formerly obtained from cork. Used in the formation of alkyd resins and polyamides. Esters are used as plasticizers and heavy duty lubricants and oils. 

The first 6 m nylon 66 stands for the number of carbons m the diamine the second for the number of carbons m the dicarboxylic acid Nylon 66 was an im mediate success and fostered the development of a large number of related polyamides many of which have also found their niche in the marketplace... 

Polyesters are a second class of condensation polymers and the principles behind their synthesis parallel those of polyamides Ester formation between the functional groups of a dicarboxylic acid and a diol... 

The polyamides poly(hexamethylene sebacamide) and poly(hexamethylene adipamide) are also widely known as nylon-6,10 and nylon-6,6, respectively. The numbers following the word nylon indicate the number of carbon atoms in the diamine and dicarboxylic acid, in that order. On the basis of this same system, poly (e-caprolactam) is also known as nylon-6. 

If a polyamide is prepared in the presence of a large excess of dicarboxylic acid, the average chain will have a carboxyl group at each end ... 

In 1978 Hiils (Mumcu et al ) described the properties of a block copolymer prepared by condensation of polytetramethylene ether glycol with laurin lactam and decane-1,10-dicarboxylic acid. The materials were introduced as XR3808 and X4006. The polyamide XR3808 is reported to have a specific gravity of 1.02, a yield stress of 24 MPa, a modulus of elasticity of 300 MPa and an elongation of break of 360%. The Swiss company Emser Werke also introduced similar... 

A wide range of polyether-polyamide block copolymers were first offered by Atochem in 1981 under the trade name Pebax. These are made by first producing a low molecular weight polyamide using an excess of dicarboxylic acid at a temperature above 230°C and under a pressure of up to 25 bar. This is then combined with a polyether by reaction at 230-280°C under vacuum (O.l-lOTorr) in the presence of a suitable catalyst such as Ti(OR)4. 

Saturated 2,2 -bis-5-oxazolones (10) react with diamines under mild conditions to form polyamides (34) of high molecular weight in quantitative yield [Eq. (21)]. These polymers are composed of dicarboxylic acid, a-amino acid, and diamine units in a regular arrangement of both head-to-tail and tail-to-tail amide groups. They represent a cross between conventional polyamides and a-amino acid homopolymers. A feature of this polymerization is that no small molecules such as H2O, NHg, or CO2 are lost during reaction. 

Polyamides are produced by the reaction between a dicarboxylic acid and a diamine (e.g., nylon 66), ring openings of a lactam, (e.g., nylon 6) or by the polymerization of w-amino acids (e.g., nylon 11). The production of some important nylons is discussed in the following sections. 

The polymer in Example 23.4 is Nylon-66 (the numbers indicate the number of carbon atoms in the diamine and dicarboxylic acid molecules). This polymer was first made in 1935 by Wallace Carothers working at DuPont (Figure 23.3). Since then, other nylons, all polyamides, have been synthesized. 

Linear step-growth polymerizations require exceptionally pure monomers in order to ensure 1 1 stoichiometry for mutually reactive functional groups. For example, the synthesis of high-molecular-weight polyamides requires a 1 1 molar ratio of a dicarboxylic acid and a diamine. In many commercial processes, the polymerization process is designed to ensure perfect functional group stoichiometry. For example, commercial polyesterification processes often utilize dimethyl terephthalate (DMT) in the presence of excess ethylene glycol (EG) to form the stoichiometric precursor bis(hydroxyethyl)terephthalate (BHET) in situ. 

PatentNumber US 6140428 A1 20001031 SIMULTANEOUS PRODUCTION OF DICARBOXYLIC ACIDS AND DIAMINES BY SPLITTING POLYAMIDES INTO THEIR MONOMERIC CONSTITUENTS Seeliger U Mueller W F Heimann F Huber G Habermann W Voss H Siegel H BASF AG... 

Diselosed is a proeess for the simultaneous production of dicarboxylic acids and diamines from a) polymers based on polyamides of dicarboxylic acids or their derivatives with diamines or b) compositions containing essentially such polymers. It involves treating these polymers or compounds with a base in alcoholic medium and subsequently converting the resulting dicarboxylate salts electrochemically into the corresponding dicarboxylic acids and bases. 

Polymers with hetero-atoms in the chain are suitable for chemical recycling of waste materials. In addition to depolymerisation (nylon 6) and solvolysis (nylon 6,6, PETP, PU) the degradation of aliphatic polyamides with dicarboxylic acids, diamines and cyclic anhydrides, especially trimellitic anhydride, becomes more and more important. The utilisation of the obtained fragments is described. 

Polyamide/polyolefin modified with dicarboxylate (propylene-maleic anhydride) SBR—MA copolymer... 

In general, polyalkylene polyamides-amines are obtained by the condensation of polyalkylenepolyamines with dicarboxylic acids. The materials are alkoxylated with an excess of ethylene oxide or propylene oxide or 1,2-butylene oxide [149],... 

The azolide method has also been used for the synthesis of polyamides and polyimides. These can be obtained by several routes First by condensation of two dihomofunctional components (dicarboxylic acid diimidazolides and diamines), secondly by condensation of a heterodifunctional compound (amino carboxylic acid and CDI), or through reaction on a polymer (for example, polymeric carboxylic acid imidazolides and amines). 

Diamine + dicarboxylic acid Polyamides (e.g., nylon 66 nylon 610)... 

Polyamides can be obtained by the melt polycondensation between dicarboxylic acids and diamines. They have the general structure as follows ... 

The use of oleochemicals in polymers has a long tradition. One can differentiate between the use as polymer materials, such as linseed oil and soybean oil as drying oils, polymer stabilizers and additives, such as epoxidized soybean oil as plasticizer, and building blocks for polymers, such as dicarboxylic acids for polyesters or polyamides (Table 4.2) [7]. Considering the total market for polymers of ca. 150 million tonnes in 1997 the share of oleochemical based products is relatively small - or, in other terms, the potential for these products is very high. Without doubt there is still a trend in the use of naturally derived materials for polymer applications, especially in niche markets. As an example, the demand for linseed oil for the production of linoleum has increased from 10000 tonnes in 1975 to 50 000 tonnes in 1998 (coming from 120000 tonnes in 1960 ) [8a]. Epoxidized soybean oil (ESO) as a plastic additive has a relatively stable market of ca. 100000 tonnes year-1 [8b]. 

Nylon-66 is made by the condensation polymerization of the dicarboxylic acid adipic acid, and 1,6-diaminohexane, an amine. (The number 66 comes from the fact that each of the two reactants contains six carbon atoms.) This reaction results in the formation of amide bonds between monomers, as shown in Figure 2.13. Condensation polymers that contain amide bonds are called nylons or polyamides. Condensation polymers that contain ester bonds are called polyesters. Polyesters result from the esterification of diacids and dialcohols. 

It has become the custom to name linear aliphatic polyamides according to the number of carbon atoms of the diamine component (first named) and of the dicarboxylic acid. Thus, the condensation polymer from hexamethylenedi-amine and adipic acid is called polyamide-6,6 (or Nylon-6,6), while the corresponding polymer from hexamethylenediamine and sebacoic acid is called polyamide-6,10 (Nylon-6,10). Polyamides resulting from the polycondensation of an aminocarboxylic acid or from ring-opening polymerization of lactams are indicated by a single number thus polyamide-6 (Nylon-6) is the polymer from c-aminocaproic acid or from e-caprolactam. 

Fully aromatic polyamides are synthesized by interfacial polycondensation of diamines and dicarboxylic acid dichlorides or by solution condensation at low temperature. For the synthesis of poly(p-benzamide)s the low-temperature polycondensation of 4-aminobenzoyl chloride hydrochloride is applicable in a mixture of N-methylpyrrolidone and calcium chloride as solvent. The rate of the reaction and molecular weight are influenced by many factors, like the purity of monomers and solvents, the mode of monomer addition, temperature, stirring velocity, and chain terminators. Also, the type and amount of the neutralization agents which react with the hydrochloric acid from the condensation reaction, play an important role. Suitable are, e.g., calcium hydroxide or calcium oxide. 

In principle, the attainment of chemical equilibrium can be accelerated by catalysts however, in contrast to polyester formation, catalysts are not absolutely essential in the above-mentioned polycondensations. The first two types of reactions are generally carried out in the melt solution polycondensations at higher temperature, e.g., in xylenol or 4-fert-butylphenol are of significance only in a few cases on account of the poor solubility of polyamides. On the other hand, polycondensation of diamines with dicarboxylic acid chlorides can be carried out either in solution at low temperature or as interfacial condensation (see Sect. 4.1.2.3). 

As in the preparation of polyesters, also in the preparation of polyamides, the reaction temperature can be considerably reduced by using derivatives of dicarbo-xylic acids instead of the free acids. Especially advantageous in this connection are the dicarboxylic acid chlorides which react with diamines at room temperature by the Schotten-Baumann reaction this polycondensation can be carried out in solution as well as by a special procedure known as interfacial polycondensation (see Examples 4-11 and 4-12). 

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