Polyamide 6-EPDM blends

Effects of maleated ethylene-propylene diene rubber (EPDM) on the thermal stability of pure polyamides, and polyamide/EPDM and polyamide/poly (ethylene terephthalate) blends kinetic parameters and reaction mechanism/Zl. Vieira, V.L. Severgnini, D.J. Maasra MS. Soldi, E.A Pinheiro, AT.N. Pires and V. ScAAilPolymer degradation and stability (2001), 74 1 151-157. 

Styrenic block copolymer blends with polyolefins are among the most widely used blends and they vary in hardness from low Shore A on the softer side to >60 D on the harder side and are used in a wide variety of applications. EPDM blends with polyolefin that are made by compounding or by direct reactor polymerization have also found several applications in the automotive industry. At low concentrations ( 20% or less) EPDM and EPR have been used as an impact modifier for polyamides [16]. 

Considerable amounts of EPM and EPDM are also used in blends with thermoplastics, eg, as impact modifier in quantities up to ca 25% wt/wt for polyamides, polystyrenes, and particularly polypropylene. The latter products are used in many exterior automotive appHcations such as bumpers and body panels. In blends with polypropylene, wherein the EPDM component may be increased to become the larger portion, a thermoplastic elastomer is obtained, provided the EPDM phase is vulcanked during the mixing with polypropylene (dynamic vulcani2ation) to suppress the flow of the EPDM phase and give the end product sufficient set. 

Commercial melt-mixed blends of EPDM and PP, dynamically vulcanized, Monsanto (Santroprene) Polyamide TPE, Atochem (Pebax)... 

S—EB—S (compounds) polyurethane/elastomer block copolymers polyester/elastomer block copolymers polyamide/elastomer block copolymers polyetherimide/polysiloxane block copolymers polypropylene/EPDM or EPR blends polypropylene/EPDM dynamic vulcanizates polypropylene/butyl rubber dynamic vulcanizates polypropylene/natural rubber dynamic vulcanizates polypropylene/nitrile rubber dynamic vulcanizates PVC/ nitrile rubber blends... 

Nylon-610 and nylon-612 produced by the condensation of hexamethylenediamine and sebacic or dodecanolc acid, respectively, are more resistant to moisture and more ductile than nylon-66. The properties of these polyamides may be improved by the formation of polyether blocks (NBC) and by blending with thermoplastics, such as EPDM, PET, PBT and TPE. 

These polyesters, [-0-(t)-C(CH3)2-(t)-C02-(t)-C0-]jj (Tg = 188°C, and HDT = 120-175°C), were introduced in 1974. The commercial resins include U-polymer , Ardel , Durel , and Arylon . Their advantages include transparency, good weatherability and high HDT. PAr has been blended with nearly all resins, including ABS, EPDM, lonomers, LCP, PA, PB, PBI, PBT, PC, PEI, PEK, PET, Phenoxy, PMB, PS, PPE, PPS, etc. Three types of PAr blends are of particular importance — those with polyesters, PEST, polyamides, PA, and with polyphenylenesulhde, PPS. A summary of PAr blends is provided in Table 1.76. 

Like binary blends, PA6/(g-PE/g-EPDM) composites are two-phased. Irrespective of the components ratio, their individual effects of melting and crystallization in blends are shown on the DSC curve. The comparative analysis of structure-morphology features for ternary blends, PA6/(g-PE/g-EPDM), and binary blends indicated that g-EPDM added to PA6/g-PE affects crystallization of the polyolefin as well as polyamide components. The results of DSC on the two types of blends, PA6/ (g-LDPE/g-EPDM) and PA6/(g-HDPE/g-EPDM), show increased crystallinity in g-PE against a binary blend (108,109). This effect results, most likely, from easier crystallization of g-HDPE in the presence of g-EPDM owing to raised molecular mobility because of plasticization by the elastomeric phase. 

As it was found by relaxation spectrometry, r spAe shifts by 5-15°C toward the lower temperature zone for blends with g-PO against the pure polyamide (109). The extent of this shift increases with g-EPDM concentration in the blends. This finding witnesses a possibihty of increasing low temperature resistance of the blends if g-EPDM is introduced. 

Blends of PET/HDPE have been treated previously in the literature [157, 158]. These are immiscible, but the addition of compatibilizers improves the mechanical properties of the blend, such as styrene-ethylene/butylene-styrene (SEBS) and ethylene propylene diene monomer (EPDM) [157], MAH [158], Poly(ethylene-stat-glycidyl metha-crylate)-graft-poly(acrilonitrile-stat-styrene) (EGMA), poly (ethylene acrylic acid), and maleated copolymers of SEBS, HDPE, ethylene-propylene copolymer (EP). The addition of compatibilizers modifies the rheological properties of blends of PET with HDPE, in such a way that increases in viscosity are observed as the component interactions augment. Changes in crystallization of PET were evaluated in blends with Polyphenylene sulfide (PPS), PMMA, HDPE aromatic polyamides, and copolyesters [159]. 

The structure of EPDM grafted onto polyamide 66 was analysed with high resolution solid state carbon-13 NMR and IR spectroscopy. Details about the EPDM rubber include the amount of mbber incorporated into this blend, the sequence analysis of the EPDM mbber and an estimate... 

The co-continuous structure and the final rheological properties of an immiscible polymer blend are generally controlled by not only the viscoelastic and interfacial properties of the constituent polymers but also by the processing parameters. For example, the effect of plasticizer on co-continuity development in blends based on polypropylene and ethylene-propylene-diene-terpolymer (PP/EPDM), at various compositions, was studied using solvent extraction. The results showed more rapid percolation of the elastomeric component in the presence of plasticizer. However, the same fuUy co-continuous composition range was maintained, as for the non-plasticized counterparts (Shahbikian et al. 2011). It was also shown that the presence of nanoclay narrows the co-continuity composition range for non-plasticized thermoplastic elastomeric materials (TPEs) based on polypropylene and ethylene-propylene-diene-terpolymer and influences their symmetry. This effect was more pronounced in intercalated nanocomposites than in partially exfoliated nanocomposites with improved clay dispersion. It seems that the smaller, well-dispersed particles interfere less with thermoplastic phase continuity (Mirzadeh et al. 2010). A blend of polyamide 6 (PA6) and a co-polyester of... 

Among the various other types of PA-TPVs investigated in the literature, PA/EPDM mbber-based TPV is interesting. As will be discussed in more detail, under impact-modified polyamides section (Sect. 19.7.1.1), binary blends of PA6 of EPDM mbbers can be compatibilized via reactive extmsion... 

The compatibUization technique has been used successfully in preparing EPDM/ polyamide and polyester blends, silicone rubber and polyamide blends, and blends of two dissimilar TPVs [25, 28-30]. 

SAN-grafted EPDM is available commercially for making styrenic blends and PVC compositions, and polyether-block polyamides (PEBA) have been promoted for polyamide blends. 

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