Polyaryletherketone blends

There have been many attempts to combine the performance advantages of polyaryletherketones (PARK) with other materials. Blends may offer lower cost and/or be used to enhance some aspects of performance. It is a tribute to the processability and stability of PARK that they can be used to improve the flow and processability of other high-temperature materials. Some blends are commercially successful. However, cost reduction can sometimes come with a complex mix of property trade-offs. Rnd users may prefer to use a pure PARK which has been characterised over many years. In addition specialist blends with complex formulations can have the effect of tying an end user to a single supplier. 

Successful blends are also limited to polymers which can survive the high processing temperatures associated with PARK. There are some references to blends with nylons or polycarbonates in which we might qnestion the process stability of the materials used. Thermal and morphological stability should be carefully checked when evalnating any PARK blend. 

Not snrprisingly the most frequently blended materials are those high-temperature polymers reviewed in Chapter 5. 

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Blends comprising sulfone polymers and other middle- to high-temperature engineering resins with at least a partially aromatic backbone structure are feasible in many cases. Such blends include sulfone polymer blends with polycarbonates, some polyesters, polyarylates, poly-etherimides, and polyaryletherketones. Blends of PPSF with poly-aryletherketones such as PEEK or PEK are particularly interesting as these blends form very finely dispersed systems with synergistic strength, impact, and environmental stress cracking resistance properties [43, 44]. 

Figure4.10 Melting point versus composition for polyaryletherketone blends (reprinted (replotted) from Harris, J. E. and Robeson, L. M.,J. Polym.Sci. Part B Polym. Phys. (1987) 25, p. 311) with permission by John Wiley Sons, Inc.)...

For reasons that are not fiiUy understood, PPSF exhibits generally improved compatibiUty characteristics over either PSF or PES in a number of systems. An example of this is blends of PPSF with polyaryletherketones (39,40). These blends form extremely finely dispersed systems with synergistic strength, impact, and environmental stress cracking resistance properties. Blends of PPSF with either PSF or PES are synergistic in the sense that they exhibit the super-toughness characteristic of PPSF at PSF or PES contents of up to 35 wt % (33,34). The miscibility of PPSF with a special class of polyimides has been discovered and documented (41). The miscibility profile of PPSF with high temperature (T > 230° C) polysulfones has been reported (42). 

Polyaryletherketone, [-( )-C0-( )-0-( )-0], was commercialized in 1980 as Victrex . It is a tough, resin with T = 143°C and T = 334°C. Blends of PEEK with PPS show synergistic effects toward tensile and flexural strength, as well as the impact resistance. 

Polyaryletherketones (PAEK) are aromatic polymers with ether and ketone linkages in the chain, viz., PEK, PEEK, PEEKK, etc. Polyetheretherketone (Victrex PEEK), [-(j)-C0-(t)-0-(t)-0-]n, was commercialized in 1980 (Tg = 143 °C, Tm = 334 °C). Commercial blends of PEEK include Sumiploy PEEK/PES/ PTFE, PEEK/LCP, Cortem PEEK/LTG, etc. Evolution of PEEK blends technology is outlined in Table 1.72. 

As discussed by Dr. A. S. Hay, polyphenylene oxide was extremely difficult to mold but a chance discovery of blends with polystyrene, made the commercialization of this Important polymer feasible. The development of heat resistant polysulfones and polyaryletherketones are excellent examples of the application of good Industrial research chemistry. Fortunately, the stories of these and other developments are told by the clever scientists who were responsible for these dramatic breakthroughs in polymer science. 

The most frequently used is TGA at constant temperature or heating rate of = 5-20°C/min in vacuum, air or inert gas. " The degradation process has been described taking into account the reactions (i) initiation by random chain scission, (ii) depropagation, and (iii) chain termination." TGA is an integral part of synthesis and characterization of HTP and their blends. For example, developing new isomeric polythioetherimides (PTEI)," polyamides based on s-triazine," polyaryletherketones (PAEK)" or polyimides (PI)" " and their... 

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