Abstract:The miscibility of perdeuterated isotactic polypropylene (d-PP) and ethylene-1-hexene random copolymer (EHR) blends, which were polymerized by metallocene catalyst, was investigated by small-angle neutron scattering (SANS) with changing hexene content in EHR and temperature above the melting point of d-PP. Flory-Huggins interaction parameter (χ d-PP/EHR) between two polymers was determined on the basis of random phase approximation (RPA). It was revealed that χd-PP/EHR decreases with increasing hexene content … Show more
“…We obtained R g,H = 49.5 Å for the hydrogenated iPP and a small χ DH value (<10 -4 ) by applying a least-mean-square method as a fitting procedure. The ratio of R g to M w 1/2 ( R g / M w 1/2 ) obtained in this experiment is 0.40 and is almost consistent with the value obtained from iPP (0.37−0.40) with narrow molecular weight distribution ( M w / M n ∼ 1.7) previously reported by other authors. , The very small χ DH value means that d-iPP and h-iPP can be recognized as equivalent species, as is also already reported. , 1 SANS profile for a d-iPP/h-iPP (50:50) blend at 190 °C (□) and its fitting results (bold line) with eq 2. 2 SANS intensities obtained from d-iPP/a(P/B) (P/B = 60:40) blend at 190 °C and their fitting results with eq 2. 3 SANS profiles for three d-iPP/a(P/B) blends at various temperatures. a(P/B) materials are aPP (A), a(P/B) (P/B = 60:40) (B), and aPB (C).…”
Section: Resultssupporting
confidence: 91%
“…It is well-known that miscibility control of polyolefin polymer blends is very important for both industrial applications and its inherent scientific interest. − To understand the miscibility between polyolefins, many researchers have performed various experiments such as morphology observation by TEM, − observation of phase diagrams by small-angle light scattering (SALS), , and estimation of χ by small-angle neutron scattering (SANS), − pressure−volume−temperature diagrams (PVT), solubility parameters, , etc. Among them, SANS is one of the most powerful experiments which can quantitatively estimate the degree of miscibility between polyolefins, and many SANS studies for polyolefin blend systems have been reported.…”
Section: Introductionmentioning
confidence: 99%
“…The SM theory was successful in explaining the miscibility behavior of isotactic PP (iPP)/ethylene−ethyl ethylene random copolymer (E x EE 1 - x ) and syndiotactic PP (sPP)/E x EE 1 - x blends when the ethylene to ethyl ethylene ratio was changed. , On the other hand, the LC theory expresses the monomer structure using lattice approximation, and it precisely describes the entropic term based on the monomer structure. The LC theory has successfully explained the miscibility of iPP/head-to-head PP blend, iPP/EHR blend, ethylene−norbornene (E x N 1 - x )/E y N 1 - y blend, etc. In general, dominant interactions between polyolefins without polar groups are dispersive forces, and hence the interaction parameters (χ) between components are usually positive.…”
The degree of miscibilityof (iPP)/atactic propylene-butene random copolymer (a(P/B)) blends has been evaluated by using χ parameters obtained from a series of SANS experiments. It was found that the observed χ value decreased with increasing the butene content in a(P/B) from approximately zero in iPP/aPP. It showed a relatively larger negative value when the butane content was high. The temperature dependence of χ for this blend system was also measured. The sign of the slope of χ vs 1/T plot was apparently affected by butene content. It changed from positive to negative with an increase of butene content in a(P/B), indicating switching of the phase behavior from a UCST to an LCST system. SANS results were analyzed with the lattice cluster (LC) theory. It is estimated that the enthalpic interaction between a propylene and a butene monomer unit is negative. The value of trans-gauche exchange energy obtained from the LC theory is found to be associated with the segment length evaluated from SANS.
“…We obtained R g,H = 49.5 Å for the hydrogenated iPP and a small χ DH value (<10 -4 ) by applying a least-mean-square method as a fitting procedure. The ratio of R g to M w 1/2 ( R g / M w 1/2 ) obtained in this experiment is 0.40 and is almost consistent with the value obtained from iPP (0.37−0.40) with narrow molecular weight distribution ( M w / M n ∼ 1.7) previously reported by other authors. , The very small χ DH value means that d-iPP and h-iPP can be recognized as equivalent species, as is also already reported. , 1 SANS profile for a d-iPP/h-iPP (50:50) blend at 190 °C (□) and its fitting results (bold line) with eq 2. 2 SANS intensities obtained from d-iPP/a(P/B) (P/B = 60:40) blend at 190 °C and their fitting results with eq 2. 3 SANS profiles for three d-iPP/a(P/B) blends at various temperatures. a(P/B) materials are aPP (A), a(P/B) (P/B = 60:40) (B), and aPB (C).…”
Section: Resultssupporting
confidence: 91%
“…It is well-known that miscibility control of polyolefin polymer blends is very important for both industrial applications and its inherent scientific interest. − To understand the miscibility between polyolefins, many researchers have performed various experiments such as morphology observation by TEM, − observation of phase diagrams by small-angle light scattering (SALS), , and estimation of χ by small-angle neutron scattering (SANS), − pressure−volume−temperature diagrams (PVT), solubility parameters, , etc. Among them, SANS is one of the most powerful experiments which can quantitatively estimate the degree of miscibility between polyolefins, and many SANS studies for polyolefin blend systems have been reported.…”
Section: Introductionmentioning
confidence: 99%
“…The SM theory was successful in explaining the miscibility behavior of isotactic PP (iPP)/ethylene−ethyl ethylene random copolymer (E x EE 1 - x ) and syndiotactic PP (sPP)/E x EE 1 - x blends when the ethylene to ethyl ethylene ratio was changed. , On the other hand, the LC theory expresses the monomer structure using lattice approximation, and it precisely describes the entropic term based on the monomer structure. The LC theory has successfully explained the miscibility of iPP/head-to-head PP blend, iPP/EHR blend, ethylene−norbornene (E x N 1 - x )/E y N 1 - y blend, etc. In general, dominant interactions between polyolefins without polar groups are dispersive forces, and hence the interaction parameters (χ) between components are usually positive.…”
The degree of miscibilityof (iPP)/atactic propylene-butene random copolymer (a(P/B)) blends has been evaluated by using χ parameters obtained from a series of SANS experiments. It was found that the observed χ value decreased with increasing the butene content in a(P/B) from approximately zero in iPP/aPP. It showed a relatively larger negative value when the butane content was high. The temperature dependence of χ for this blend system was also measured. The sign of the slope of χ vs 1/T plot was apparently affected by butene content. It changed from positive to negative with an increase of butene content in a(P/B), indicating switching of the phase behavior from a UCST to an LCST system. SANS results were analyzed with the lattice cluster (LC) theory. It is estimated that the enthalpic interaction between a propylene and a butene monomer unit is negative. The value of trans-gauche exchange energy obtained from the LC theory is found to be associated with the segment length evaluated from SANS.
“…This result suggests that the contributions of the SCBs in mLLDPE and the LCBs in LDPE to the values of their blends are negligible, as reported elsewhere (Alamo et al, 1997). Note that the determined values are significantly lower than the theoretical ones at the spinodal point ( sp ) given by the following equation (Seki, 2000):…”
Small-angle neutron scattering (SANS) analysis was performed to investigate the miscibility of blends of metallocene-catalyzed octene linear low-density polyethylene (octene-mLLDPE) and low-density polyethylene (LDPE). The quantitative SANS analysis found that the blends are miscible in both the melt and the quenched states. Moreover, this analysis confirmed that the radii of gyration of octene-mLLDPE(D) and LDPE(H) remain unchanged in the quenched state and that the two polymer components cocrystallize via fast crystallization from the melt state. research papers 162 Tae Joo Shin et al. Miscibility of octene-LLDPE and LDPE blends
“…A primary difficulty in experimentally assessing the phase behavior of polyolefin blends, especially at melt process temperatures, is the similarity in chemical structure of the blend constituents. The most rigorous studies have relied on extrapolation of results with model copolymers to predict the phase behavior of real polymers 4–8. However, in a recent review of binary blends of high‐density polyethylene with low‐density polyethylenes of different chain microstructure, Zhao and Choi9 noted that the effects of branch content, molecular weight averages, molecular weight distribution, and branch length are still controversial.…”
New challenges and opportunities for polyolefin blends arise from the recent introduction of olefin block copolymers (OBCs). In this study, the effect of chain blockiness on the miscibility and phase behavior of ethylene-octene (EO) copolymer blends was studied. Binary blends of two statistical copolymers (EO/EO blends) that differed in comonomer content were compared with blends of an EO with a blocky EO copolymer (EO/OBC blends). The blends were rapidly quenched to retain the phase morphology in the melt and the phase volumes were obtained by atomic force microscopy (AFM). Two EOs of molecular weight about 100 kg/mol were miscible if the difference in octene content was less than about 10 mol % and immiscible if the octene content difference was greater than about 13 mol %. The blocky nature of the OBCs reduced the miscibility and broadened the partial miscibility window of the EO/OBC blends compared with the EO/EO blends. The EO/OBC blends were miscible if the octene content difference was less than 7 mol % and immiscible above 13 mol % octene content difference. It was also found that the phase behavior of EO/OBC blends strongly depended on blend composition even for constituent polymers of about the same molecular weight. Significantly more demixing was observed in an OBC-rich blend (EO/OBC 30/70 v/v) than in an OBC-poor blend (EO/OBC 70/30 v/v). An interpretation based on extractable fractions of the OBC described the major features of the EO/OBC (30/70 v/v) blends. V V C 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys
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