High-impact propylene/ethylene copolymer

C. Kock, N. Aust, C. Grein, M. Gahleitner, Polypropylene/polyethylene blends as models for high-impact propylene-ethylene copolymers. Part 2 Relation between composition and mechanical performance. J. Appl. Polym. Sci. 130, 287-296 (2013)... 

To complete the assembly of a cell, the interleaved electrode groups are bolted to a cov er and the cover is sealed to a container. Originally, nickel-plated steel was the predominant material for cell containers but, more recently plastic containers have been used for a considerable proportion of pocket nickel-cadmium cells. Polyethylene, high impact polystyrene, and a copolymer of propylene and ethylene have been the most widely used plastics. 

Around Izod notch Low-density polyethylene Ethylene-propylene block copolymers Cellulose nitrate and propionate ABS and high-impact polystyrene Bis-phenol A polycarbonate... 

On the other hand, high impact poly(styrene) (HIPS), ABS, acrylonitrile-ethylene-propylene-based rubber/styrene copolymer resin (AES), acrylonitrile/acryl-based rubber/styrene copolymer resin (AAS) show excellent impact strengths, but these resins are inferior in chemical resistance and abrasion resistance. 

ABA ABS ABS-PC ABS-PVC ACM ACS AES AMMA AN APET APP ASA BR BS CA CAB CAP CN CP CPE CPET CPP CPVC CR CTA DAM DAP DMT ECTFE EEA EMA EMAA EMAC EMPP EnBA EP EPM ESI EVA(C) EVOH FEP HDI HDPE HIPS HMDI IPI LDPE LLDPE MBS Acrylonitrile-butadiene-acrylate Acrylonitrile-butadiene-styrene copolymer Acrylonitrile-butadiene-styrene-polycarbonate alloy Acrylonitrile-butadiene-styrene-poly(vinyl chloride) alloy Acrylic acid ester rubber Acrylonitrile-chlorinated pe-styrene Acrylonitrile-ethylene-propylene-styrene Acrylonitrile-methyl methacrylate Acrylonitrile Amorphous polyethylene terephthalate Atactic polypropylene Acrylic-styrene-acrylonitrile Butadiene rubber Butadiene styrene rubber Cellulose acetate Cellulose acetate-butyrate Cellulose acetate-propionate Cellulose nitrate Cellulose propionate Chlorinated polyethylene Crystalline polyethylene terephthalate Cast polypropylene Chlorinated polyvinyl chloride Chloroprene rubber Cellulose triacetate Diallyl maleate Diallyl phthalate Terephthalic acid, dimethyl ester Ethylene-chlorotrifluoroethylene copolymer Ethylene-ethyl acrylate Ethylene-methyl acrylate Ethylene methacrylic acid Ethylene-methyl acrylate copolymer Elastomer modified polypropylene Ethylene normal butyl acrylate Epoxy resin, also ethylene-propylene Ethylene-propylene rubber Ethylene-styrene copolymers Polyethylene-vinyl acetate Polyethylene-vinyl alcohol copolymers Fluorinated ethylene-propylene copolymers Hexamethylene diisocyanate High-density polyethylene High-impact polystyrene Diisocyanato dicyclohexylmethane Isophorone diisocyanate Low-density polyethylene Linear low-density polyethylene Methacrylate-butadiene-styrene... 

If the hard blocks are longer than the soft ones, such as in SBS with a high styrene content, the hard phase will be continuous, and the rubbery phase is present as domains (see Figure 9.6). In such a case SBS behaves as a high-impact PS. Another example of this type is a PP/EP block copolymer tails of EP (random copolymer of ethylene and propylene) on the PP chains segregate into rubbery domains in the PP matrix, which improve the impact strength. 

The following TPs are the main thermoforming materials processed high-impact and high-heat PS, HDPE, PP, PVC, ABS, CPET, PET, and PMMA. Other plastics of lesser usage are transparent styrene-butadiene block copolymers, acrylics, polycarbonates, cellulosics, thermoplastic elastomers (TPE), and ethylene-propylene thermoplastic vulcanizates. Coextruded structures of up to seven layers include barriers of EVAL, Saran, or nylon, with polyolefins, and/or styreneics for functional properties and decorative aesthetics at reasonable costs.239-241... 

Product specifications The process can produce a broad range of propylene-based polymers, including homopolymer polypropylene, random copolymers and terpolymers, heterophasic impact and specialty impact (up to 25% bonded ethylene) copolymers as well as high stiffness, high-clarity copolymers. 

As an option, the polymer can then be fed to a fluidized bed gas-phase reactor, operated in series vith the MZCR, where additional copolymerization can take place to yield high-impact copolymer PP. This gas-phase reactor may be bypassed when homopolymer or random copolymers are produced. In this reactor, the elastomeric phase (ethylene/propylene rubber) is generated within the porous homopolymer matrix that resulted from the first reaction stage. The pores, developed inside the polymer particle in the MZCR upstream, allow the rubber phase to develop without the formation of agglomerates resulting from the sticky nature of the rubber. 

A number of block copolymers prepared with Ziegler-Natta catalysts have been reported however, in most cases the compositions may include significant amounts of homopolymer. The Ziegler-Natta method appears to be inferior to anionic polymerization for synthesizing carefully tailored block copolymers. Nevertheless, bock copolymers of ethylene and propylene (Eastman Kodak s Pofyallomers) have been commercialized. Unlike the elastomeric random copolymers of ethylene and propylene, these are high-impact plastics exhibiting crystallinity characteristics of both isotactic polypropylene and linear polyethylene. They also contain homopolymers in addition to block copolymers. 

Blends of polyolefins (e.g., HPDE/LDPE, LDPE/ ethylene copolymers, PP/EPDM, PP/HDPE/EPDM, HDPE/butyl rubber) have been commercial since the late 1960 s and early 1970 s. Specific film formulations were commonly based on polyolefin blends to achieve the proper balance of processing, environmental stress crack resistance, modulus, toughness, cling, transparency, filler acceptance, printability, tear resistance, shrinkage characteristics, and permeability. Ethylene-propylene mbber (EPR, EPDM) was commonly incorporated into polypropylene as an impact modifier at moderate levels and as a flexibilizer at high levels. One of... 

Products The process can produce a broad range of propylene-based polymers, including mono-and bimodal (medium/wide/very wide molecular weight distribution) homopolymer PP, high stiffness homopolymers, random copolymers and terpolymers, high-clarity random copolymers as well as two compositions copolymer/random copolymer, twin-random or random/heterophasic copolymer). Conventional heterophasic impact copolymers (with improved stiffness/impact balance) can be produced with the second additional gas phase reactor, with ethylene/ propylene rubber content up to 40%. 

As mentioned extensively, PPE is not mainly used as such, but in polymeric blends and copolymers to faciUtate the fabrication. Some of these copolymers act also as impact modifiers for example, block copolymers built from styrene, ethylene, butylene, and propylene. Naturally, the impact can be improved by using high impact poly(styrene) (HIPS) instead of ordinary PS in blends. Other impact modifiers include rubbery materials, such as poly(octenylene), and ethylene propylene diene monomer rubber. 

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. 

The commercial names of polymers do not always fulfill what they promise. Not only more or less branched homopolymers of various molar masses are encountered under the name, poly(ethylene), but also copolymers of ethylene with propylene, butene-1, etc. Commercially, not only the homopolymers of styrene are included under the poly(styrene) designation, but also copolymers with acrylonitrile (SAN), blends of poly(styrene) with various elastomers (HIPS = high impact poly(styrene)) and graft copoly-mers-blends of acrylonitrile, butadiene, and sytrene. The styrene monomeric unit is the main component in all of these polymers thus, these polymers are all included in the poly(styrene) family, although their properties can differ from each other (Table 36-4). 

TPO materials are defined as compounds (mixtures) of various polyolefin polymers, semicrystalline thermoplastics, and amorphous elastomers. Most TPOs are composed of polypropylene and a copolymer of ethylene and propylene called ethylene—propylene rubber (EPR) [2]. A common rubber of this type is called ethylene propylene diene monomer rubber (EPDM), which has a small amount of a third monomer, a diene (two carbon-carbon double bonds in it). The diene monomer leaves a small amount of unsaturation in the polymer chain that can be used for sulfur cross-linking. Like most TPEs, TPO products are composed of hard and soft segments. TPO compounds include fillers, reinforcements, lubricants, heat stabilizers, antioxidants, UV stabilizers, colorants, and processing aids. They are characterized by high impact strength, low density, and good chemical resistance they are used when durability and reliability are primary concerns. 

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