Blends of polyesters

Blends of PBTP and polycarbonate (PC), marketed by General Electric (USA) under the name Xenoy, overcome some of the deficiencies of PC, in particular, improving the processing behaviour, hydrolysis resistance and low-temperature impact performance. The amorphous regions of the PBTP appear to be miscible with the wholly amorphous PC, with the glass transition of the 50 50 blend at 100°C being intermediate between that of PC (150°C), and that of PBTP (35-40°C). The PBTP crystallizes to a small extent. The impact behaviour is improved by the inclusion of a small quantity of acrylic rubber. A demanding application for the 50 50 blend, with added rubber, is the 

The blend, when properly processed, offers toughness down to — 70 C, is tolerant of recycling, (provided scrupulous care is taken over drying), and is reasonably resistant to hydrolysis, as shown by immersion in deionized water at 40°C for 30 weeks. 

Finally, blends at different blend ratios are available, e.g. 80 20 PBTPiPC, which is recommended for improved high-temperature performance (see also Chapter 11). 

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The role of specific interactions in the plasticization of PVC has been proposed from work on specific interactions of esters in solvents (eg, hydrogenated chlorocarbons) (13), work on blends of polyesters with PVC (14—19), and work on plasticized PVC itself (20—23). Modes of iateraction between the carbonyl functionaHty of the plasticizer ester or polyester were proposed, mostly on the basis of results from Fourier transform infrared spectroscopy (ftir). Shifts in the absorption frequency of the carbonyl group of the plasticizer ester to lower wave number, indicative of a reduction in polarity (ie, some iateraction between this functionaHty and the polymer) have been reported (20—22). Work performed with dibutyl phthalate (22) suggests an optimum concentration at which such iateractions are maximized. Spectral shifts are in the range 3—8 cm . Similar shifts have also been reported in blends of PVC with polyesters (14—20), again showing a concentration dependence of the shift to lower wave number of the ester carbonyl absorption frequency. 

Blends of polyester with cotton (qv) or viscose are first dyed with disperse dyes, then with sulfur dyes (see Fibers, polyester Fibers, regenerated CELLULOSics). Disperse and sulfur dyes can also be appHed simultaneously in a pad—dry—thermofix/chemical reduction pad—steam sequence. In this case, the sulfur dyes cannot be used in thein reduced form because of the effect of the sodium sulfide on the disperse dye. Therefore, this method is confined to the solubilized sulfur dyes or sulfur dyes in the dispersed form. 

Estapol, a blend of polyester/polyether resins NA, not available PBA, polybutyl acrylate PUV, polyurethane varnish PVAL, polyvinylalcohol SVF, silicone vacuum fluid fiber volume fraetion. 

PERMANENT-PRESS RESIN. A thermosetting resin used as a textile impregnate or fiber coating to impart crease resistance and permanent hot-creasing to suitings, dress fabrics, etc. Chemicals such as formaldehyde and maleic anhydride are the basis of these products. The resin is cured after the fabric has been tailored into a garment. A permanent-press fabric that requires no resin has been developed (a blend of polyester with cotton or rayon). 

Scouring is mainly designed to remove the natural oils and waxes from the cotton portion and the finish oils which manufacturer add to polyester fibres when extruded. Blends of polyester/cotton can be scoured with alkaline scouring agents as per conditions shown in Table 4.16. Trisodium phosphate can also be used as an TABLE 4.16... 

The Thermosol process (Chapter 23) is applied extensively to the continuous dyeing of cloth made of blends of polyester and cellulosic fibres. 

Moldability of aryl polyesters have also been improved by the use of polybutylene terephthalate (PET) instead of PET or by the use of blends of PET and PET. PET under the trade name of Celanex, Valox, Gafite and Versel is being produced at an annual rate of 25 thousand tons. Copolymers of carbonate and aryl esters, acrylics and aryl esters, and imide and aryl esters as well as physical blends of polyesters and other polymers are available. These aryl polyesters are being used for bicycle wheels, springs, and blow molded containers. The properties of typical aryl polyesters are as follows ... 

A general review of Interchange Reactions Involving Condensation Polymers describes early work on redistribution reactions in the melt blends of polyesters, polyamides, and polyester + polyamide [Kotliar, 1981],... 

Molten polyesters show low viscosity and small extmdate swell. For these reasons, they have been blended with amorphous polymers to improve the latter s processability and chemical resistance. Elastomers have also been added to polyesters to improve impact resistance. Blends of polyester (either PET or PBT) with polycarbonate, PC, are the most popular (viz., Bay/oF, BCT4201, Calibre , Dialoy P, Ektar MB (with PCTG), Idemitsu SC, MakroblencT, MB4300, NovadoF, Pocan , R2-9000, Sabre , SC 600, Stapron E, Ultra-blencF KR, Valox , Xenoy 1000, etc.). Presence of PC in PET/PC increases crystallization rate of PET, which translates into faster injection molding cycle and lower part distortion upon demolding than those observed for neat PET. 

Blend families, i.e., blends of polyphenylene ether (PPE), blends of polyesters (PEST), blends of polycarbonate of bisphenol-A (PC), tend to be appropriate for certain types of apphcations which require the special attributes of the major blend component. For this reason, it is possible to group blend families together under the major resin component and to list the types of applications that have been commercialized. 

Figure 14.15. Percentage gloss retention as a function of exposure for blends of polyester and acrylic copolymers.

To make an assessment of this method a series of coatings were produced based on blends of polyester and acrylic copolymers. The actual QUV data (see Figure 14.15) show a gradual transition from the less durable polyester to the more durable acrylic. The photo-initiation rates were calculated from the nitroxide decay curves,... 

The HWM staple fibers have essentially all of the best attributes of regular rayon except for a few important differences. They swell less in water, are somewhat stiffer due to higher cellulose DP (IV) and orientation, and are almost twice as strong and resist dimensional change. Fabrics made from HWM fibers can be dyed and later finished (cross-linked) by much the same techniques as those used for cotton fabrics. In 50-50 blends of polyester and HWM rayon, fabrics can be made that are virtually indistinguishable from some cotton counterparts [282]. 

In addition to the above, techniques such as scanning electron microscopy (SEM) are used to study the morphology of the blends of polyesters with other resins and compounded polyesters (paints), which indicate the homogeneity and phase behaviour with domain size of different components present in the system. To study the morphology of polyester-melamine or polyester-epoxy blend and their mixtures with different reinforcing agents, transmission electron microscopy (TEM) is now used along with SEM. Atomic force microscopy (AFM) may sometimes be used to study the surface structure of polyester blends. 

Following up on the work that used knitted brics as extension sensors to measure breathing rate 000, some samples were knitted in three different structures, using a yam that is a blend of polyester and stainless steel in a proportion of 80/20 % (Bekaert Bekinox Nm 50) and has a perfectly textile touch comparing to a pure stainless steel yam. lire first experiments showed that the sensors had limited performance. The main problems presented by this sensor are its high non-linearity and hysteresis, and an evident instability of the electrical resistance values measured, producing a fluctuation of the signals. 

Blends of Polyesters with Other Polymers and/or Biomolecules... 

Evstatiev, M., Petrovich, S., and Fakirov, S. (1993) Microfibrillar reinforced composites from binary and ternary blends of polyesters and Nylon 6. Macromolecules, 26, 5219 - 5226. 

Texin 5370 is a blend of polyester-based polyurethane and polycarbonate. It offers high impact strength and high stiffness. Steam sterilization or boiling should be avoided (Tables 4.3, 4.12, and 4.13). 

FluorGSC6nt PigiUGntS. There are three basic types of fluorescent pigments A thermoplastic pigment based on a polyamide resin, a thermoplastic pigment based on a polyester resin matrix, and a pigment based on a blend of polyester and polyamide resin. 

Fakirov S, Evstatiev M and Schultz J M (1993) MicrofibrUlar reinforced composite from binary and ternary blends of polyesters and nylon 6, Macromolecules 34 4479-4669. 

A special blend of polyester polymers of excellent clarity, colour and light stability which can be spray applied, alone or added to gelcoat for repairs or to upgrade a tooling gel coat. 

Several types of reactive processing have been identified [13]. Here only two more important will be mentioned (1) Reaction between functional, highly reactive groups, e.g., to compatibilize PPE/PA blends. (2) The trans-reactions, e.g., transesterification during blending of polyesters [19-21], or trans-reactions between amide and ester groups, leading to formation of PA-PEST copolymers [7,22,23]. 

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