Polyamides and polyurethanes

This type of adhesive is generally useful in the temperature range where the material is either leathery or mbbery, ie, between the glass-transition temperature and the melt temperature. Hot-melt adhesives are based on thermoplastic polymers that may be compounded or uncompounded ethylene—vinyl acetate copolymers, paraffin waxes, polypropylene, phenoxy resins, styrene—butadiene copolymers, ethylene—ethyl acrylate copolymers, and low, and low density polypropylene are used in the compounded state polyesters, polyamides, and polyurethanes are used in the mosdy uncompounded state. 

Nearly all of the polymers produced by step-growth polymerization contain heteroatoms and/or aromatic rings in the backbone. One exception is polymers produced from acyclic diene metathesis (ADMET) polymerization.22 Hydrocarbon polymers with carbon-carbon double bonds are readily produced using ADMET polymerization techniques. Polyesters, polycarbonates, polyamides, and polyurethanes can be produced from aliphatic monomers with appropriate functional groups (Fig. 1.1). In these aliphatic polymers, the concentration of the linking groups (ester, carbonate, amide, or urethane) in the backbone greatly influences the physical properties. 

Whereas polyetheylene, polypropylene, and polystyrene are virtually non-biodegradable, only specially modified, not widely employed, polyamides and polyurethanes are susceptible to biodegradation [2]. Consequently, the use... 

Polyureas have higher Melting points than the corresponding Polyamides and polyurethanes, e.g. ... 

In polymer applications derivatives of oils and fats, such as epoxides, polyols and dimerizations products based on unsaturated fatty acids, are used as plastic additives or components for composites or polymers like polyamides and polyurethanes. In the lubricant sector oleochemically-based fatty acid esters have proved to be powerful alternatives to conventional mineral oil products. For home and personal care applications a wide range of products, such as surfactants, emulsifiers, emollients and waxes, based on vegetable oil derivatives has provided extraordinary performance benefits to the end-customer. Selected products, such as the anionic surfactant fatty alcohol sulfate have been investigated thoroughly with regard to their environmental impact compared with petrochemical based products by life-cycle analysis. Other product examples include carbohydrate-based surfactants as well as oleochemical based emulsifiers, waxes and emollients. 

Recent work on the synthesis, structure and some properties of macromolecules bearing furan rings is discussed. Two basic sources of monomers are considered, viz. furfural for monomers apt to undergo chain polymerization and hydroxymethylfurfural for monomers suitable for step polymerization.Within the first context, free radical, catiomc and anionic systems are reviewed and the peculiarities arising from the presence of furan moieties in the monomer and/or the polymer examined in detail. As for the second context, the polymers considered are polyesters, polyethers, polyamides and polyurethanes. Finally, the chemical modification of aU these oligomers, polymers and copolymers is envisaged on the basis of the unique reactivity of the furan heterocycle. 

Therefore, die polarity and solubility of polymer can be modified deliberately by varying the nature of the components. High aqueous solubilities of polyamides and polyurethane threaded with crown ethers or CD are intriguing, because this observation implies potential applications of the polyrotaxane concept in coatings, adhesives, and water-borne processing. The observation of the emulsification of... 

The synthesis of optically active polymers is an important area in macromolecular science, as they have a wide variety of potential applications, including the preparation of CSPs [31-37]. Many of the optically active polymers with or without binding to silica gel were used as CSPs and commercialized [38]. These synthetic polymers are classified into three groups according to the methods of polymerization (1) addition polymers, including vinyl, aldehyde, isocyanide, and acetylene polymers, (2) condensation polymers consisting of polyamides and polyurethanes, and (3) cross-linked gels (template polymerization). The art of the chiral resolution on these polymer-based CSPs is described herein. 

Several polyamides and polyurethanes have been synthesized by condensation polymerization and used as the precursors for the preparation of different CSPs. These CSPs showed different chiral recognition properties than those of addition polymers. AUenmark and Andersson [67] prepared a CSP containing silica gel supported by v-triazinc derivatives of L-valine isopropyl esters (Fig. 14) and the... 

As already mentioned, there has been renewed interest for using carbohydrates as a source of chemicals since the 1980s with the development of the chemistry of furanic compounds, particularly for the preparation of nonpetroleum derived polymeric materials, such as polyesters, polyamides and polyurethanes.[17,19]... 

Scheme 12.1 Thermal scission of aliphatic polyester, polyamide and polyurethane through rearrangement of six or four atoms...

Automotive plastic waste components are, in addition to PP and PVC, styrene copolymers, rubber, polyamides and polyurethanes. 

On the other hand, there are data suggesting that amides have a rather high value for association as pure liquids. Trifan and Terenzi measured IR spectra of several polyamides and polyurethanes from 25°C to 300°G. They deduce an average —AH of 8.5 1.2 kcal/mole for the polymers. Until more data are available we must draw the provisional conclusion that —AH for amide N—bonds in crystals (and possibly in pure liquids) may be much larger than in solutions. Under any circumstances, however, we arc reminded that the data of Davies establish empirically the substantial contribution of the amide groups to the stability of the amide crystal structures. 

Poly(dimethylsiloxane), polyether-block-polyamides and polyurethane membranes Polyether-block-polyamides membrane and polybutadiene membrane... 

On an industrial scale, the SFE-FTIR couple has been successfully used to determine aramid, polyamide and polyurethane-based fibres, which require a different finish for textile processing [127], By using CO, at 350 atm, 75°C and a flow-rate of 1.2 ml/min, the polyurethane finish [poly(dimethylsiloxane) oil] was thoroughly extracted within the first 10 min by contrast, less than 35% of sorbitol derivatives present in the aramid finish could be separated after 20 min. The separation efficiency for polyamide finish components varied between 74 and 100%, with relative standard deviations for the most extractable finishes — which were recovered by more than 98% — ranging from 5.7 to 21%. 

Use As cross-linking agents in epoxy coatings, imparting high flexibility and adhesion at low temperatures. Other possible uses are in polyamide and polyurethane coatings, adhesives, elastomers and foams, as intermediates for textile and paper treatment, and viscosity-index improvers in lubricating oils. 

Carbohydrate-based polyamides and polyurethanes constitute two major families of polymers and hence the interest in preparing aminosugars and, from them, the corresponding isocyanates. This wide research field has produced very interesting materials including the first chiral nylon-type polyamides [16]. 

Typical polyamides and polyurethanes prepared from aminosugars, both from anhydroalditols and protected monosaccharides, are shown in Figures 1.8 and 1.9, respectively. 

Similarly, polyamidation and polyurethane-forming reactions can be written as WWW" COOH -I- H2N-WWW www-CONH-www + H2O (5.2)... 

The use of Diels-Alder and platinum-catalyzed polyaddition reactions of vinylferrocene derivatives to prepare ferrocene-containing polycarbosilanes has also been described. " These reactions were also used to prepare materials with additional functional groups that led to ferrocene and silicon-containing polyesters, polyamides, and polyurethanes. Molecular weights varied in the range of 3,800-6,000 and products were liquids or elastomers. 

Microwave-assisted polycondensation reactions in ILs have also allowed the enhanced synthesis of polyamides and polyurethanes the comparison between microwave synthesis conditions in ILs with conventional heating methods and conventional organic solvents has also been addressed [92, 93]. Pretreatment methods combining microwave irradiation and ILs for cellulose dissolution and modification have been also proposed [94, 95]. Microwave irradiation can enhance the solubility of cellulose in ILs and decrease the degree of polymerization of regenerated cellulose after IL dissolution, which can be beneficial for improving cellulose hydrolysis [95]. 

For the same number of chain atoms in the repeat unit, polyureas, polyamides, and polyurethanes have higher melting points than polyethylene, while polyesters have lower. 

The hetero-chain polymers, notably the polyesters, polyamides and polyurethanes, can also act as a source of new monomers or oligomers by hydrolysis and alcoholysis. This recycling process (sometimes called... 

The second general pattern of polymerization is step-growth or condensation polymerization. While terminal alkenes are the most common monomers in chain-growth polymerization, bifunctional molecules are the characteristic monomers for step-growth polymerization. The polyester-, polyamide-, and polyurethane-forming reactions shown below are examples of step-growth polymerizations ... 

HMF is a suitable precursor for the synthesis of bifunctional furan monomers as summarized in Scheme 4. All these monomers can be used to prepare polycondensates by step-growth reactions with the other corresponding bifunc-tional monomers derived either from petrochemical precursors or from renewable resources. The polycondensates obtained, such as polyesters, polyamides, and polyurethanes, etc. have been characterized [107-113]. Scheme 5 shows another approach for the synthesis of bifunctional monomers through acid-catalyzed condensation of the corresponding mono-functional furan derivatives with an aldehyde... 

Another approach involves the use of difunctional telechelic polyolefins with ester, hydroxyl, and amine terminal groups. Telechelic polyolefins can be used to make polyesters, polyamides, and polyurethanes with low permeability to solvents and gases. 

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