Ethylene-Propylene Block Copolymers

Chiu, H.-T. Chiu, W.-M. The toughening behavior in propylene-ethylene block copolymer filled with carbon black and styrene-ethylene butylene-styrene triblock copolymer. Mater. Chem. Phys. 56, 108-115 (1998). 

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... 

Propylene/ethylene block copolymer, 10% ethylene, 416 Novolen 3200 HX... 

Salt of aeid methylenebis(2,4-di-t-butylphenol) phosphate (NAll) is added in an amount of 300 to 2000 ppm as a nucleating agent to a propylene/ethylene block copolymer composition for exterior automotive parts. ... 

Furthermore, the crazes in PP show other similar characteristics to those of amorphous polymers. They grow apparently normal to the direction of major tensile stress which somewhat deviates from the tensile direction because of spherulitic structure. There are similar environmental effects on craze initiation (see also Environmental stress cracking of polypropylene in this book). Crazing is also an important source of toughness in toughened PP alloy systems such as propylene-ethylene block copolymers. 

Linse, P, Phase Behavior of Poly(ethylene oxide)-Poly(propylene oxide) Block Copolymers in Aqueous Solutions, Journal of Physical Chemistry 97, 13896, 1993. 

Holland RJ, Parker EJ, Guiney K, Zeld FR. Fluorescence probe studies of ethylene oxide/propylene oxide block copolymers in aqueous solution. J Phys Chem 1995 99 11981-11988. 

SEES Styrene-ethylene-propylene-styrene block copolymer. 

Linse, P. 1993. Micellization of poly(ethylene oxide)-poly(propylene oxide) block copolymers in aqueous solution.Macromolecule26 4437—4449. 

Pandya, K., K. Lad, and P. Bahadur. 1993. Effect of additives on the clouding behavior of an ethylene oxide-propylene oxide block copolymer in aqueous solutbbM.S. Pure Appl. Chem. 30 1-18. 

Reverse ethylene oxide/propylene oxide block copolymers (in which a hydrophilic core of PEO is terminated at both ends with hydrophobic PO moieties) are used in industrial applications. This is because of the different and unique performance properties compared to the conventional block copolymers, where a hydrophobic PO core is block copolymerized with EO. Dufour and Guyot [30] have built on this observation and synthesized Surfmers in which a PEG core (about 37 EO units) was tipped with about 10 PO units to further react with a chlorine-carrying polymerizable group or with maleic anhydride to produce reactive Surfmers. 

Fig. 7.35 Ethylene oxide/propylene oxide block copolymer.

Calvo P, Remunan-Lopez, Vila-Jato JL, Alonso MH (1997b) Chitosan and chitosan/ethylene oxide-propylene oxide block copolymer nanoparticles as novel carriers for proteins and vaccines. Pharmaceut Res 14 1431-1436... 

The mapping of ethoxylated fatty alcohols and ethylene oxide-propylene oxide block copolymers by 2D chromatography was discussed by Trathnigg et al. [95]. They combined LAC and SEC and were able to determine the chemical composition distribution and the molar mass distribution of the polyethers. 

The use of olefin rubbers [18] as good impact modifiers for sPS when used in conjunction with S-B or S-B-S block copolymers, which may be hydrogenated in the butadiene phase, has also been described. Instead of butadiene, isoprene can be used. Examples of the olefinic polymers are polyethylene, ethylene-propylene rubbers (EPR) and polypropylene-(ethylene propylene rubber) block copolymers. Here the styrene block copolymers presumably function as... 

Poly(ethylene oxide-fo-propylene Synthetic block copolymers of ethylene CH2 OCHCH3 Chains carry up to 2 (OH) end groups. 

PS blends with EPDM were compatibilized by addition of either SB (polystyrene/polybutadiene di-block copolymer) or SEP (polystyrene/ethylene propylene di-block copolymer) and were blended in a corotating twin-screw extruder T = 200°C (Table 11.9). The strands were quenched and pelletized. Some of the pellets were injection-molded (200°C) into 4 mm-thick specimens and irradiated to 50 kGy (3-MeV electron accelerator). Another part of the pellets was similarly irradiated and then injection-molded. The samples for notched Izod impact testing (ASTM D256) were annealed for 24 h at 80°C, or were left at RT for 3 weeks, before testing [van Gisbergen et al., 1990,1991b]. 

The most extensive group of ether surfactants is that of polyethoxylated long-chain alcohols and related ethoxylated products considered, in view of their practical importance, in a separate section. Other ether nonionics of importance are polypropylene glycols, propoxylated alcohols, block-copolymers of ethylene oxide and propylene oxide, block-copolymers of ethylene oxide and butylene oxide [8, 16-20], block-copolymers having a hydrophobic polydimethylsiloxane moiety [19, 21], as well as alkyl polyglycerides, alkyl polyglycosides, derivatives of maltose and other saccarides. 

With the purpose of conferring thermosensitivity to chitosan-based hydrogels. Park et al. proposed the grafting of carboxylic acid-terminated poly(ethylene oxide-h-propylene oxide) block copolymer (Pluronic) onto the primary amine of chitosan, mediated by EDC coupling agent [102]. With the same purpose, Wang et al. grafted poly(N-isopropyl acrylamide) (NiPAM) chains onto chitosan by the copolymerization of acrylic acid-derivatized chitosan and N-isopropylacrylamide (NIPAAm) in aqueous solution [103]. 

III. The third group includes polymerizations carried out in the presence of nonionic macromolecular emulsifiers, among which ethylene oxide-propylene oxide block copolymers and polyvinyl alcohol are most largely used. 

Melik-Nubarov NS, Pomaz 00, Dorodnych T, et al. Interaction of tumor and normal blood cells with ethylene oxide and propylene oxide block copolymers. FEES Lett 1999 446 194-198. 

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