Dynamic vulcanized alloys

Ru04 Staining—When there is no solubility differences or unsaturation this possibility is explored, e.g., knit explored line between two DVA s (dynamic vulcanized alloys). (Figure 8)... 

TEM (refer to Figure 1) is used whenever a more in-depth study (when domain sizes are less than 1 micron or so) is required on polymer phase morphologies such as dynamically vulcanized alloys and Nylon/EP filler location as in carbon black in rubber compounds and also in the morphology of block copolymers. Thin sections are required and take anywhere from one hour to one day per sample depending on the nature of the sample. They must be 100 nm in thickness and are prepared usually by microtoming with a diamond knife at near liquid nitrogen temperatures (-150° C). The same contrasting media for SEM apply to TEM. In addition, PIB backbone polymers scission and evaporate in the TEM which helps... 

Blend of (1) and (2) type categories mostly include the modification of engineering thermoplastics with another thermoplastic or rubber. PS-EPDM blends using a low-molecular weight compound (catalyst) Lewis acid have been developed [126]. Plastic-plastic blends, alloys of industrial importance, thermoplastic elastomers made by dynamic vulcanization, and rubber-rubber blends are produced by this method. 

Keywords Dynamic vulcanization Polymer blends and alloys Reactive processing Thermoplastic elastomers Thermoplastic vulcanizates... 

Kocsis (1999) In Shonaike GO, Simon GP (eds) Polymer blends and alloys - thermoplastic rubbers via dynamic vulcanization. Marcel Dekker, Ne w York... 

Commercially important elastomeric thermoplastic alloys are dynamically vulcanized blends of polypropylene with high volume fractions of EPDM, polybutadiene rubber, nitrile rubber, and butyl rubber (Santoprene , Vyram , Geolast and Trefsin ) all currently sold by Advanced Elastomer Systems, a joint venture of Monsanto and Exxon. Another recent member of the commercial dynamically cured elastomeric thermoplastic alloys is the blend of PVC and a crosslinked ethylene copolymer (Alcryn , DuPont). The current consumption of all the elastomeric thermoplastic alloys in the USA is over 23 kton/y, with the EPDM/PP blend (Santoprene ) assuming about 90% of the market share. 

In contrast to the rigid TPOs described above, low-modulus/flexible grades of TPO blends are also produced commercially. In flexible TPOs, the rubber content can be as high as 60 %, and in some cases, the dispersed rubber may also be partially cross-linked during the mixing without losing the thermoplastic character of the matrix. However, the latter type of dynamically vulcanized elastomeric alloys or thermoplastic vulcanizate rubbers (TPVs) are considered as a separate class of elastomeric materials and hence will be discussed under elastomer blends. On the other hand, the soft TPO blends discussed here contain a low-modulus olefln copolymer elastomer as the major component with some polypropylene added to impart melt processability. 

Dynamically vulcanized, elastomeric thermoplastic alloys or TPVs display properties as good as or even better than the block copolymers, viz., a high degree of rubber elasticity yet good melt processability. The main advantages of the thermoplastic vulcanizate elastomer blends over the uncured thermoplastic/elasto-mer blends are... 

The three major types of TPEs are block copolymers such as SEES (styrene-ethylene-butylene-styrene block copolymer) (Kraton by Kraton Polymer), polyether— polyester (Hytrel by DuPont), rubber/plasticblends (900 series Sumitomo Chemical), and dynamically vulcanized rubber/plastic alloys (Innoprene by Kumho Polychem, Santo prene by Exxon-Mobil, Sarlink by DSM, Unipene byTeknor Apex). Figure 3.28 shows the cost versus general performance comparison for different TPEs [31]. 

Karger-Kocsis J (1999) Thermoplastic rubbers via dynamic vulcanization, in Polymer Blends and Alloys (Eds. Shonaike G O and Simon G P) Marcel Dekker, New York, pp. 125-153. 

Considerable improvements in properties result, compared to RRPP, if cross-linking/curing is introduced into the rubber particles. PR modified, rubber compounds. Such materials may be known as dynamically crosslinked polyolefin elastomer or TPO-XL or, as a d5mamically vulcanized material or, as an elastomeric alloy (EA) or, as an elastomeric alloy thermoplastic vulcanizate (EA-TPV). If enough plastic is present (say 50%), the compound can still be easily processed by thermoplastic techniques. 

---