Ethylene-hexene blends

Rytter et al. reported polymerizations with the dual precatalyst system 14/15 in presence of MAO [30]. Under ethylene-hexene copolymerization conditions, 14/MAO produced a polymer with 0.7 mol% hexene, while the 15/MAO gave a copolymer with ca. 5 mol% hexene. In the mixed catalyst system, the activity and comonomer incorporation were approximate averages of what would be expected for the two catalysts. Using crystallization analysis fractionation (CRYSTAF) and differential scanning calorimetry (DSC) analysis, it was concluded in a later paper by Rytter that the material was a blend containing no block copolymer [31],... 

Yamaguchi et al. subsequently investigated the mechanical properties of blends of polypropylene with ethylene-hexene copolymers (110,111). Interestingly... 

As discussed earlier, ethylene propylene rubber (EPR or EPM) has been blended with PP and PE to improve the impact strength and to render the materials softer. Recently, metallocene catalysts or postmetallocene catalysts provide new pathways to generate elastic copolymers that can replace EPR. These pathways possess cheaper manufacturing cost and generate new materials with better compatibility to PP or PE. Such new materials included ethylene-propylene random copolymers with dominant ethylene component (33-34) or propylene-dominant component (35 1), propylene-ethylene block copolymer (42), ethylene-octene copolymer (43), poly(propylene-co-ethylene) (44), ethylene-hexene copolymer (45), ethylene-butene copolymer (46), low isotactic PP (47), and stereoblock PP (48). These materials are generally compatible with PP or PE, thus can be used to tailor the toughness (or the softness) of... 

Compositions comprised 10-80 wt% low-MW polyethylene, HOPE [p > 940 kg m ], and 20-90 wt% high-MW ethylene-hexene copolymer, LLDPE [p < 955 kg m ]. The blends had a MFI > 0.05 g/10 min. The blend showed improved optical and physical properties, resulting in better blow- molded products ... 

Thermoplastic olefin (TPO) compositions typically consist of an immiscible blend of an isotactic polypropylene mixed with a polyolefin elastomer that acts as an impact modifier. It is possible to toughen these compositions further by using ethylene-propylene, ethylene-octene or ethylene-hexene impact modifiers. 

The miscibility of PP with other hydrocarbon polymers has also been studied recently. Yamaguchi et al. [7] examined blends of PP with ethylene-hexene and ethylene-butene copolymers by microscopy and thermal analysis. The copolymers that had large amounts of the... 

Fig. 7.29. dE/d 2(2) for (a) a 20/80 blend of HDPE-D and heterogeneous (Ziegler-Natta-catalyzed) ethylene-hexene LLDPE copo ymer en an ( ) a 25/75 blend of HDPE-D with a metallocene-based copolynier. (Reproduced with permission from [191]. Copyright 2002 American Chemical Society.)... 

There are, however, some miscible polyolefin blend systems. There is evidence of miscibility (sometimes limited) between various copolymers/terpolymers of ethylene with amorphous isotactic polypropylene [20 to 22]. These copolymers include ethylene-butene, ethylene-hexene and ethylene-octene copolymers ... 

Garcia RA, Carrero A, Aroca M, Prieto O, Dominguez C Slow crack growth resistance in resin blends of chromium and metallocene catalyzed ethylene-hexene copolymers for pipe appHcations, Polym Eng Sci 48(5) 925—933, 2008. 

Fig. 11,27 The dependence of the crystallization temperature, Tc, for linear polyethylene blends with different copolymers as a function of composition. hydrogenated poly(butadiene) A ethylene-hexene o ethylene-butene. Crystallization was carried out by cooling at 10 K min from melt. (50)...

Polyolefin blends always show a raised swell of the extrudate jet in comparison with homopolymers (83). This was shown earlier (88) for LDPE/LLDPE blends. Some researchers reported (89,90) a significant influence of the molecular structure on properties of the polymer melts the polymers whose chains contain starlike branches show increased sensitivity toward shear stresses applied onto their melts. The presence of comblike segments increases the melt strength. For example, the addition to LLDPE up to 10 wt% of a comblike polymer (copolymer of a polyethylene macromonomer, k. 8000gmol , and ethylene and hexene) allows raising the strength of polymer melt almost by one decimal order (86). The MFl of the blend varies less substantially. The melt strength of LLDPE blends can be... 

Yu.V. Zavgorodnev, K.A. Prokhorov, G.Yu. Nikolaeva, E.A. Sagitova, P.P. Pashinin, T.M. Ushakova, L.A. Novokshonova, E.E. Starchak, V.G. Krasheninnikov. Raman stmctural study of reactor blends of ultrahigh molecular weight polyethylene and random ethylene/1-hexene copolymers. Laser Phys. 23, 025701 (8 pp) (2013)... 

Polyolefin blends PP/poly(ethylene-co-l-hexene) X12 showed a min at 50 % 1-hexene comonomer 14... 

Polyethylene blends having toughness and elastic recovery comparable to those of plasticized PVC comprised >50 wt% of a copolymer of ethylene and either butene or hexene [LLDPE, p = 880-915 kg MI < 1 dg min , long-chain branching =0.5-1.5 long chalns/l.OOOC, M > 200 kg mol ] >5 wt% of a copolymer of ethylene and either vinyl acetate or ethyl acrylate, EVAc or EEA and 5-30 wt% liquid hydrocarbon oil. The blends showed essentially no yield point and behavior similar to that of cross-linked materials, although they were not cross-linked (strain recovery). They were found competitive with plasticized PVC in terms of both physical properties and economics... 

Polyethylene blends having toughness and elastic recovery comparable to those of plasticized PVC comprised >50 wt% of a copolymer of ethylene and either butene or hexene P LDPE,... 

Fig. 17. Cocrystallization of ethylene/1-hexene copolymers in Crystaf as a function of cooling rate. Dotted lines are the profiles calculated from the Crystaf analyses of the individual components in the blend.. . . Calculation experiment. From Ref. 14.

Fig. 20. Comparison of TREF and Crystaf blend peak resolution for ethylene/1-hexene copolymers as a function of cooling rate-----Tref ... Crystaf. From Ref 14.

Fig. 31 Comparison between Crystaf and Tref profiles of blends of ethylene/1-hexene copolymers with known multimodal CCD measured at the same cooling rate [29]...

Two factors were found to regulate co crystallization in Crystaf (1) CR [29] and (2) the similarity of chain crystallizabilities [67]. Figure 37 shows the effect of CR on cocrystallization of a trimodal blend of ethylene/1-hexene copolymers. Fast CRs can induce cocrystallization and distort the experimental Crystaf profile. It is important to note that this phenomenon exists even at the typically used CR of 0.1 °C. 

In our recent work [67], we investigated the effect of comonomer type on CO crystallization using a series of ethylene/1-olefin copolymers with four comonomer types propylene, 1-hexene, 1-octene, and 1-dodecene. Four blends, one for each copolymer type, were prepared such that they crystallized at the same temperature range and had similar ATq to ehminate the effect of similarity of chain crystalHzabihties. The Crystaf results of these blends indicated that the comonomer type of the parent samples did not appreciably influence their cocrystalHzation behavior, as illustrated in Fig. 39. 

Fig. 39 Effect of comonomer type on cocrystallization at a cooling rate of 0.1 °C/min for blends with the same comonomer type. BPED blend of ethylene/1-dodecene copolymers, BPEO blend of ethylene/l-octene copolymers BPEH blend of ethylene/1-hexene copolymers, BPEP blend of ethjdene/propylene copolymers [67]...

The first results on 2D-LC for polyolefins were published by Ginsburg et al. [167, 177] and Roy et al. [178]. Roy et al. [178] applied a separation system that was previously described by Macko et al. [158, 159,162]. This system was applied to the separation of ethylene/1-octene copolymers regarding chemical composition and molar mass. Ginzburg et al. [177] used an instrument that has recently been developed and commercialized by PolymerChar (Valencia, Spain). They used the on-line coupling of gradient HPLC and SEC to separate blends of PP stereoisomers, ethylene/propylene mbbers, ethylene/norbomene copolymers and ethylene/1-hexene copolymers, all at an operating temperature of 160°C using a stationary phase of Hypercarb and a mobile phase of 1-decanol-TCB. 

Fig. 31 Contour diagram of the HT-2D-LC separation of (a) a blend of PE, poly-1 -hexene and an ethylene-1-hexene and (b) a blend of PE and PPs with different tacticities stationary phase Hypercarb (first dimension) and PL Rapide H (second dimension) mobile phase gradient 1-decanolATCB (first dimension) and TCB (second dimension) temperature 160°C detector ELSD. (Reprinted from [167] with permission of Elsevier Limited)...

Yamaguchi M and Nitta K H (1999) Optical and acoustical investigation for plastic deformation of isotactic polypropylene/ethylene-1-hexene copolymer blends, Polym Eng Sd 39 833-840. 

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