Ethylene-propylene copolymers polypropylene blends

Xe NMR of Ethylene/Propylene Copolymers in Blends and Block-copolymers with Polypropylene... 

Owing to adequate level of compatibility between polypropylene and ethylene-propylene copolymers, simple blends of these two polymers have been known for a long time. Impact modified... 

LINEAR POLYETHYLENE/POLYPROPYLENE/ETHYLENE-PROPYLENE COPOLYMER TERNARY BLENDS ... 

The TREF-GPC analysis can be performed with an additional composition sensor (CH3 sensor), as discussed in previous sections. This is especially important for ethylene propylene copolymers or blends since crystallizability is influenced in the case of PP by both tacticity and ethylene incorporation, as discussed for Fig. 4. The composition sensor provides a means to assign the crystallization temperature to one or the other polymer. The analysis of a high impact PP containing a significant amount of PE homopolymer is shown in Fig. 40. A small peak eluted before the iPP is clearly associated with PE by having a significantly lower methyl content than the overall concentration response. The PE peak is eluted on the tail of the iPP where other EP species are also eluted (as discussed with Fig. 19) and the molar mass of the PE peak could be differentiated from the polypropylene part. 

Toughened polypropylene may be prepared by block copolymerization in which ethylene monomer is added during the final stages of the polymerization of propylene (4). Thus, some polypropylene chains would contain an end block of rubbery ethylene-propylene copolymer. Alternatively, a blend of an elastomeric copolymer of ethylene and propylene (EPR or EPDM) with isotactic polypropylene (PP) can produce an impact-resistant polymer (5). 

Blends between Isotactic Polypropylene and Ethylene Propylene Copolymers... 

Figure 6.29. Infrared curves of (1) polypropylene-linear polyethylene blend, (2) ethylene-propylene copolymer rubber, (3) propylene-ethylene polyallomer. (Hagenmeyer and Edwards, 1966.)...

Improvements of some of the end-use properties are generally obtained with the simultaneous worsening of other end-use properties. For instance, rubber particles (ethylene/propylene copolymers) are usually introduced into homopropylene matrixes in order to increase the impact resistance of polypropylene resins. However, this normally causes the decrease of the flexural modulus of the polymer blend, which is often undesirable [ 1 ]. Therefore, optimum operation conditions can only be defined in terms of a tradeoff among the many end-use properties that are required for a specific final apphcation. 

Polypropylene, 100 parts PP, blended with 8-25 parts of amorphous ethylene-propylene copolymer, EPR, and 2-10 parts crystalline EPR showed improved impact strength. In the Idemitsu patent, PP was blended with maleated LDPE, EVAc, and inorganic filler, to give blends with good melt strength and rigidity... 

Linear low-density polyethylene, LLDPE, was blended Bahl et al. (1985) with low-density polyethylene, 10-45 wt% LDPE polypropylene, PP and/or ethylene-propylene copolymer [with a high propylene content], 2-15 wt%... 

Semicrystalline polyolefin blends and method of their preparation were described. The blends were reported to show enhanced inter-spherulitic and interlamellar strength. The first polymer should have higher crystallinity and crystallization temperature than the second. Thus, 50-99.9 wt% PP was blended with ethylene-a-olefin copolymers, either a stereo block polypropylene or an ethylene-propylene copolymer, EPR... 

These are the first patents on PP/PE/EPR blends. Polypropylene/polyethylene, PP/PE, blends were compatibilized by addition of ethylene-propylene copolymer, EPR. The resulting blends showed improved low-temperature brittle point and Izod impact strength. In UCC patent, 50-96 wt% was blended with 2-25 wt% PE and 2-25 EPR and/or PIB... 

Polypropylene, PP, or polyethylene, PE, was blended with ethylene-propylene copolymer, EPR, and ethylene-acetoxybicycloheptene copolymer, to increase impact and tensile strength, as well as brittle resistance. In the later patent, PP and EPR were separately dissolved then blended, precipitated, and processed. The blends showed fine, uniform dispersion of the rubber phase, resulting in superior mechanical properties... 

Polypropylene, PP, or poly (pentene-co-propylene) was reactor blended with ethylene-butene or ethylene-pentene copolymer. The product was melt blended with PP to give material with improved performance. In the second patent, ethylene-propylene copolymer, EPR, was blended with PP. The alloys showed good mechanical properties. In the Sumitomo patent, to improve impact strength, PP was blended with 5-30 wt% of either polyhexene or polyoctene... 

Polypropylene, PP, blends with low-density polyethylene, 5-20 wt% LDPE, and ethylene-propylene copolymer, 1-15 wt% EPR showed excellent transparency and mechanical properties ... 

An elastomer which upon heating turns into regularly behaving linear polymer. Polystyrene-polybutadiene block copolymers, polypropylene blends with ethylene-propylene-diene terpolymer provide examples. 

Block copolymers made from ethylene and propylene are valuable industrial materials. They can be used as thermoplastic elastomers and as compatibOizing agents for homopolymer blends. The properties of this type of copolymer depend on the microstructure of the blocks, the relative lengths of the blocks, and the overall molecular v eight. An ABA triblock copolymer structure containing crystalline A blocks and an amorphous B block can exhibit elastomeric behavior. The crystalline "hard" blocks can consist of isotactic or syndiotactic polypropylene (iPP or sPP) units or linear polyethylene (PE). The amorphous "soft" blocks can consist of atactic polypropylene (aPP) or ethylene-propylene copolymer (ethylene-propylene rubber, EPR). 

A TSC study of isotactic and atactic polypropylene, high density polyethylene, ethylene-propylene block copol)uners, ethylene-propylene rubbers and blends thereof [8] in the y and p relaxation range helped to identify the molecular origin of the relaxation peaks. Two 3 processes were observed in the copolymer samples, one (p,) around —5°C, the other one (Pj) at about -50°C. The former is attributed to the PP chains, while the latter is ascribed to microscopically random ethylene-propylene rubber segments. 

We have found an extreme combustion behavior for a system polypropylene-polypropylene-co-polyethylene [238], It can be explained in terms of oxidative degradation of polymer materials. We studied the features of autooxidation and combustibility of blends of isotactic polypropylene (PP) and ethylene-propylene copolymers (PP-co-PE) as thin films (50-80 ). ASTM D2863 (ISO 4589 Part 2) was used to determine the oxygen index (LOI) for polymer films 140 by 52 mm. 

There are many other commercial examples of polymer blends. Polycarbonate can be blended with an acrylonitrile-butadiene-styrene terpolymer to give a PC-ABS blend. Polypropylene impact can be improved by the addition of ethylene-propylene copolymers, which are sometimes called ethylene-propylene-rubber (EPR). Ethylene, propylene, and a diene monomer (EPDM), such as ethylidene norbomene, is also used to impart impact and flexibiUty to polypropylene. 

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