Thermoplastic behavior

EPDM-Derived Ionomers. Another type of ionomer containing sulfonate, as opposed to carboxyl anions, has been obtained by sulfonating ethylene—propjlene—diene (EPDM) mbbers (59,60). Due to the strength of the cross-link, these polymers are not inherently melt-processible, but the addition of other metal salts such as zinc stearate introduces thermoplastic behavior (61,62). These interesting polymers are classified as thermoplastic elastomers (see ELASTOLffiRS,SYNTHETIC-THERMOPLASTICELASTOLffiRS). 

Elastomeric polypropylenes with thermoplastic behavior can be prepared from conformationally dynamic metallocenes such as bis(2-arylindenyl)zirconium dichlorides. These can exist in two conformations in the course of the chain lifetime a chiral rac isomer which is stereodirecting and an achiral meso isomer which is aspeciflc. The resulting polymer consists of blocks of isotactic polypropylene alternating with runs of atactic material (equation 12). 

Poly(aryl ketones) (PEEK, PEK, and PEKK) are commercial high temperature polymers offering an excellent combination of properties combined with thermoplastic behavior. Poly(aryl ether ketone) PAEK blends have been reviewed by Harris and Robeson [1989]. Miscibility with PEI (Ultem 1000 GE) and other PI containing isopropylidene bridging units was noted. Arzak et al. [1997] reviewed the performance ofPEEK/PEI blends and noted a synergistic behavior in ductility and impact strength as reported earlier. Utility of these blends as a thermoplastic matrix candidate for advanced composites has been proposed [Harris and Robeson, 1989 Davis et al., 1992]. 

TPE are rubber-elastic at temperatures from 20 °C to -1-120 °C (assuming no major deformations), but show thermoplastic behavior in the melting range (160-180 °C). 

Other reusable finishing products are thermoplastic hotmelt grades that can be remelted. Because of this thermoplastic behavior they are not suitable for washable applications. To achieve wash resistance, reactive hotmelt systems should be used, being curable using humidity or UV, though not reusable. 

The Gieseler test is the only one that attempts to measure the actual extent of the plasticity of fluidity attained. The Gieseler test is used to characterize coals with regard to thermoplastic behavior and is sometimes an important tool used for coal blending for commercial coke manufacture. The maximum fluidity determined by the Gieseler is very sensitive to weathering (oxidation) of the coal. 

Reasonably high molar mass PUs can be obtained. These PUs exhibit a fair thermal stability with no significant weight loss below 200°C. PUs based on imdecylenic acid show a thermoplastic behavior with well-identified melting transitions. PUs prepared from imdecylenic acid using different methods show different glass and melting transitions. 

Finally, the use of flexible ligands for designing ID lanthanide coordination polymers could be of interest as far as the synthesis of polymers with interesting optical properties and exhibiting a thermoplastic behavior is considered. 

Thermoplastic behavior Thermoplastic polymers Thermosetting polymers Vegetable fibers... 

Thermoplastic behavior Physical changes observed in a pol)rmer as it is heated. 

Outstanding properties " biodegradability, biocompatibility, thermoplastic behavior ... 

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