Abstract:The characteristic ratios of three samples of poly( 1-hexadecene) with different tacticities were evaluated from intrinsic viscosity and molecular weight data obtained with a size exclusion chromatograph with dual (concentration plus viscosity) detector. No significant differences were found for the characteristic ratio in the studied range of tacticities. Theoretical calculations for the unperturbed dimensions were also performed for these samples by using the rotational isomeric state model, and compared wit… Show more
“…The population enhancement of the more extended trans conformer (at the expense of the gauche ) requires the chain dimension to undergo an increase beyond the level anticipated from the behavior generated by the presence of methyl and ethyl groups. 6 Chain dimensions as a function of m b for atactic poly(olefin)s. − ,, The identities of the polymer acronyms follow; PE = polyethylene; PEB-2 = polyethylene−butene copolymer with two ethyl branches per 100 backbone carbons; PP = polypropylene; PEE = poly(ethyl−ethylene); PPEN = polypentene; PHEX = polyhexene; POCT = polyoctene; PDEC = polydecene; PHDEC = poly(hexadecene). The open symbols are polyolefin samples where the data are given in refs −13.…”
Section: Discussionmentioning
confidence: 99%
“…Chain dimensions as a function of m b for atactic poly(olefin)s. − ,, The identities of the polymer acronyms follow; PE = polyethylene; PEB-2 = polyethylene−butene copolymer with two ethyl branches per 100 backbone carbons; PP = polypropylene; PEE = poly(ethyl−ethylene); PPEN = polypentene; PHEX = polyhexene; POCT = polyoctene; PDEC = polydecene; PHDEC = poly(hexadecene). The open symbols are polyolefin samples where the data are given in refs −13.…”
A chain-straightened poly(R-olefin) series was prepared via the use of a Ni(II) R-diimine catalyst. The resulting polymers are structurally nearly equivalent to ethylene-propylene copolymers with the exception that methyl groups can be evenly spaced along the polymer main chain. The monomers used ranged from ethylene to 1-decene (excluding 1-heptene and 1-nonene). With the exception of 1-decene, the polyolefins prepared have similar plateau moduli, ∼1.5 MPa at 323 K. This is comparable with values determined over the last 40+ years for copolymers formed using conventional Ziegler-Natta catalysis. Thus, the chain-straightening polymerization systems yield amorphous ethylene-propylene like polymers from single, or mixed, R-olefin monomer feeds. Using this unique type of polymerization allows for the avoidance of ambient temperature gaseous ethylene and propylene while permitting the use of higher molecular weight R-olefins that are both abundant and inexpensive.
“…The population enhancement of the more extended trans conformer (at the expense of the gauche ) requires the chain dimension to undergo an increase beyond the level anticipated from the behavior generated by the presence of methyl and ethyl groups. 6 Chain dimensions as a function of m b for atactic poly(olefin)s. − ,, The identities of the polymer acronyms follow; PE = polyethylene; PEB-2 = polyethylene−butene copolymer with two ethyl branches per 100 backbone carbons; PP = polypropylene; PEE = poly(ethyl−ethylene); PPEN = polypentene; PHEX = polyhexene; POCT = polyoctene; PDEC = polydecene; PHDEC = poly(hexadecene). The open symbols are polyolefin samples where the data are given in refs −13.…”
Section: Discussionmentioning
confidence: 99%
“…Chain dimensions as a function of m b for atactic poly(olefin)s. − ,, The identities of the polymer acronyms follow; PE = polyethylene; PEB-2 = polyethylene−butene copolymer with two ethyl branches per 100 backbone carbons; PP = polypropylene; PEE = poly(ethyl−ethylene); PPEN = polypentene; PHEX = polyhexene; POCT = polyoctene; PDEC = polydecene; PHDEC = poly(hexadecene). The open symbols are polyolefin samples where the data are given in refs −13.…”
A chain-straightened poly(R-olefin) series was prepared via the use of a Ni(II) R-diimine catalyst. The resulting polymers are structurally nearly equivalent to ethylene-propylene copolymers with the exception that methyl groups can be evenly spaced along the polymer main chain. The monomers used ranged from ethylene to 1-decene (excluding 1-heptene and 1-nonene). With the exception of 1-decene, the polyolefins prepared have similar plateau moduli, ∼1.5 MPa at 323 K. This is comparable with values determined over the last 40+ years for copolymers formed using conventional Ziegler-Natta catalysis. Thus, the chain-straightening polymerization systems yield amorphous ethylene-propylene like polymers from single, or mixed, R-olefin monomer feeds. Using this unique type of polymerization allows for the avoidance of ambient temperature gaseous ethylene and propylene while permitting the use of higher molecular weight R-olefins that are both abundant and inexpensive.
“…The properties of these polymers vary dramatically depending on stereo‐regularity and the length of the alkyl substituent at the double bond in an 1‐alkene molecule 1–3. Poly(1‐alkenes) with longer linear side chains derive their crystallinity from the side chain rather than from the polymer backbone 2–5. They usually have two melting points attributed to the crystallization of side chains of atactic and isotactic poly(1‐alkenes), respectively.…”
ABSTRACT:The block copolymer of poly(1-hexadecene) (PHD) and polypropylene (PP) was effectively synthesized by the sequential polymerization of propylene and 1-hexadecene by using highly isospecific TiCl 3 /Cp 2 Ti(CH 3 ) 2 (Cp ϭ cyclopentadienyl). The block copolymers had two separate melting temperatures of constituent blocks. The modulus of PHD-PP block copolymer was enhanced as the content of sequentially polymerized PP block was increased. The elongation at break showed positive deviation at the intermediate compositions from the simple additive values of constituent homopolymers. Shape memory effect which utilizes the crystalline PHD block as a reversible phase and the crystalline PP block as a fixed structure was examined.
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