Polyamides and Polyesters

ETHYLENE We discussed ethylene production in an earlier boxed essay (Section 5 1) where it was pointed out that the output of the U S petrochemi cal industry exceeds 5 x 10 ° Ib/year Approximately 90% of this material is used for the preparation of four compounds (polyethylene ethylene oxide vinyl chloride and styrene) with polymerization to poly ethylene accounting for half the total Both vinyl chloride and styrene are polymerized to give poly(vinyl chloride) and polystyrene respectively (see Table 6 5) Ethylene oxide is a starting material for the preparation of ethylene glycol for use as an an tifreeze in automobile radiators and in the produc tion of polyester fibers (see the boxed essay Condensation Polymers Polyamides and Polyesters in Chapter 20)... 

Synthetic Fiber and Plastics Industries. In the synthetic fibers and plastics industries, the substrate itself serves as the solvent, and the whitener is not appHed from solutions as in textiles. Table 6 Hsts the types of FWAs used in the synthetic fibers and plastic industries. In the case of synthetic fibers, such as polyamide and polyester produced by the melt-spinning process, FWAs can be added at the start or during the course of polymerization or polycondensation. However, FWAs can also be powdered onto the polymer chips prior to spinning. The above types of appHcation place severe thermal and chemical demands on FWAs. They must not interfere with the polymerization reaction and must remain stable under spinning conditions. 

Substituted amides (not of the alkanolamide variety) are sold to diverse low volume markets. They have some utility ki polymers such as polyethylene, ethylene-vinyl acetate copolymers, acryUc polymers, PVC, polyamides, and polyesters. They have been found effective as pharmaceutical processkig aids, defoamers (qv), antimicrobials, pesticides, kisect repellents, dispersion stabilizers, and corrosion inhibitors. 

Over 250,000 metric tons of microcrystaUine cellulose have been sold siace its commercialisation ia 1962 and demand continues to iacrease. Its utihty has led to development of other coUoidal polymer microcrystals (see Colloids). For example, polyamides and polyesters from recycled materials can be biodegraded to give microcrystals having a size of 30 nm (37). 

The maleimide is prebuilt into the molecule in a separate step. Maleimidobenzoic acid [17075-07-7] or its acid haUde was used to synthesize maleintide-terrninated polyamides (16,17) or polyesters (27) from amino- or hydroxy-terminated polyamides and polyesters, respectively. The Hterature on bismaleimide prepolymers and bismaleimide building blocks is quite extensive (28), but only a limited number of BMI building blocks have been used for commercial resin formulations. 

A scan of the literature over the years 1980—1991 shows that most of the current dimer activity iavolves the reaction of dimer acids to form a huge variety of polyamide and polyester stmctures to modify their properties for a wide range of iadustries and uses. Many of these property modifications seem to make use of the flexihili ing properties or adhesion-promoting properties of the dimer stmcture. 

Phenothiophosphine ring-containing polyamides and polyesters were also prepared by the polycondensation of 2,8-bischloroformyl-lO-phenylphenothiophos-phine 5,5, 10-trioxide with aromatic diamines such as 4,4 -diaminodiphenyl ether and 4,4 -diaminodiphenyl-methane, and bisphenols such as 4,4 -dihydroxybiphe-nyl and 4,4 -dihydroxydiphenylmethane, respectively [159]. These polymers are soluble in polar aprotic solvents and also exhibit good heat and fire resistance. Phosphorus containing high performance polymers are shown in Table 6. 

The alkene and diene polymers discussed in Sections 7.10 and 14.6 are called chain-growth polymers because they are produced by chain reactions. An initiator adds to a C=C bond to give a reactive intermediate, which adds to a second alkene molecule to produce a new1 intermediate, which adds to a third molecule, and so on. By contrast, polyamides and polyesters are called step-growth polymers because each bond in the polymer is formed independently of the others. A large number of different step-growth polymers have been made some of the more important ones are shown in Table 21.2. 

Step-growth polymers, such as polyamides and polyesters, are prepared by reactions between difunctional molecules. Polyamides (nylons) are formed by reaction between a diacid and a diamine polyesters are formed from a diacid and a diol. 

Polyamides and Polyesters Step-Growth Polymers 818 21.10 Spectroscopy of Carboxylic Acid Derivatives 822... 

TPEs prepared from rubber-plastic blends usually show poor high-temperature properties. This problem could be solved by using high-melting plastics like polyamides and polyesters. But, often they impart processing problems to the blends. Jha and Bhowmick [49] and Jha et al. [50] have reported the development and properties of novel heat and oil-resistant TPEs from reactive blends of nylon-6 and acrylate rubber (ACM). The properties of various thermoplastic compositions are shown in Table 5.4. In this kind of blend, the plastic phase forms the continuous phase, whereas... 

In 1929 Carothers proposed a generally useful differentiation between two broad classes of polymers condensation polymers in which the molecular formula of the structural unit (or units) lacks certain atoms present in the monomer from which it is formed, or to which it may be degraded by chemical means, and addition polymers, in which the molecular formula of the structural unit (or units) is identical with that of the monomer from which the polymer is derived. Condensation polymers may be formed from monomers bearing two or more reactive groups of such a character that they may condense intermolecu-larly with the elimination of a by-product, often water. The polyamides and polyesters referred to above afford prime examples of condensation polymers. The formation of a polyester from a suitable hydroxy acid takes place as follows ... 

Typical additive packages for engineering thermoplastics have been described by Titzschkau [9], such as processing aids for PA, PP, or PET/PBT, three-component additive packages for polyamides and polyesters (nucleating agent, lubricant and process heat stabiliser) and coated copper stabilisers for polyamides. Additive packages or combinations of up to five or more additives are quite common. A typical white window PVC profile formulation comprises an acrylic impact modifier, TiC>2, CaCC>3, calcium stearate, a... 

One previous synthesis of ferrocene-containing condensation polymers via interfacial methods at room temperature has been reported by Knobloch and Rauscher, who formed low molecular weight polyamides and polyesters by reacting l,l -bis(chloro-formyl)ferrocene with various diamines and diols. Further, Carraher and co-workers have utilized interfacial techniques in the formation of other types of organometallic polymers. 

Polyamide and polyester fibres are generally scoured using an alkyl poly(oxyethylene) sulphate and sodium carbonate. Some polyester qualities are subjected to a causticisation treatment with sodium hydroxide in the presence of a cationic surfactant to give a lighter fabric with a silkier handle [154,156]. This treatment involves etching (localised saponification) of the polyester surface and is broadly analogous to the S-finish used on triacetate fibres. The process has attracted considerable interest in recent years but its... 

Thus the Endgroup analysis method is quite useful for the determination of the Molecular weight of the polymers that possesses endgroups which can be determined precisely by some analytical reaction. In addition to Polyamides and polyesters, where the Endgroup analysis method is commonly used, the method can also be used for polysaccharides. 

Of equally high industrial potential as intermediate chemicals are the various HMF-derived products for which well-worked-out, large-scale adaptable production protocols are available. Of these, the 5-hydroxymethyl-furoic acid, the 2,5-dicar-boxylic acid, the 1,6-diamine, and the respective 1,6-diol (framed in Scheme 2.12) are the most versatile intermediate chemicals of high industrial potential, as they represent six-earbon monomers that could replace adipic acid, alkyldiols, or hexamethy-lenediamine in the production of polyamides and polyesters. 

Hydrolysis of Copolyamide-esters (CPAEs) by Lipase (jj,). CPAEs were synthesized by the amide-ester interchange reaction between polyamide and polyester. The length of the polyamide blocks was measured after hydrolysis of ester bonds in CPAE by alkali at 30 C. The infrared spectra after hydrolyzing ester bonds on CPAEs showed that the ester bonds were almost completely removed. The molecular weight distribution of polyamide blocks was examined by GPC (Table II). The following samples were used CPAE-1 (reaction time for synthesis, 1 hr) and CPAE-2 (reaction time, U hr) composed of nylon 6 and PCL at a 50/50 molar ratio, CPAE-3 (reaction time, 1 hr) and CPAE-U (reaction time,... 

Condensation polymers synthesized from single reactants are named in a similar manner. Examples are the polyamides and polyesters produced from amino acids and hydroxy acids, respectively. Thus, the polymer from 6-aminocaproic acid is named poly(6-aminocaproic acid)... 

The addition polymerization reaction of dihydroxy compounds with diisocyanates sets in on mixing the two components and gentle warming. Under proper conditions, linear polyurethanes with molecular weights up to about 15,000 can be obtained. As in the case of polyamides and polyesters, the softening point of the aliphatic polyurethanes depends on the number of carbon atoms between the urethane groups. 

Nature has long used reactions such as these to produce interesting solids such as cotton (seed pod), hemp (grass), and silk (cocoons for worms while they develop into moths) as fibers that we can strand into rope or weave into cloth. Chemists discovered in the early twentieth century that cellulose could be hydrolyzed with acetic acid to form cellulose acetate and then repolymerized into Rayon, which has properties similar to cotton. They then searched for manmade monomers with which to tailor properties as replacements for rope and sdk. In the 1930s chemists at DuPont and at ICl found that polyamides and polyesters had properties that could replace each of these. [Linear polyolefins do not seem to form in nature as do condensation polymers. This is probably because the organometaUic catalysts are extremely sensitive to traces of H2O, CO, and other contaminants. This is an example where we can create materials in the laboratory that are not found in nature.]... 

Fibres are, as a result of the spinning process, molecularly oriented, and they have, therefore, a 2 to 3 times higher stiffness than the non-oriented polymer (e.g. polyamide and polyester textile fibres). With the highest attainable orientation, such as in aromatic polyamides (Twaron and Kevlar), and in the PE-fibre (Dyneema) the stiffness can be a hundred times higher than the one in the unoriented condition ... 

The polymers can be categorised as formaldehyde containing and formaldehyde free and as thermoset or thermoplastic resins. Typical formaldehyde containing resins are melamine formaldehyde sulfonamide resins, where the sulfonamide is ortho and para toluenesulfonamide. The sulfonamide, which is a solvent for the dye, undergoes a condensation polymerisation with formaldehyde and melamine, the latter acting as a cross-linking agent. Non-formaldehyde, thermoplastic resins are usually polyamides and polyesters. 

The presence of a phenylene group in these polyamides and polyesters increases the heat resistance dramatically. Thus the Tg of polyethylene tere-phthalamide (aramid) is 300 °C and that of PET is 265 C. Poly-/>-oxybenzoate (Ekonol) does not melt but decomposes at 480 C. 

Mechanochemical syntheses of some macromolecular complexes of Mn with polyamides and polyesters have been achieved. Simionescu et al. [93] reported the ultrasonic mechanochemical condensation of polyethylene terephthalate,... 

---