“…A U-shaped curve of χ suggests an occurrence of UCST, as shown in Figure . Namely, the theory shows that thesepolymer blends have UCST-type miscibility, as observed experimentally in the previous work . The slight temperature dependence of χ 1 / r 1 in the high temperature range may be due to a small difference in the free volume because, as shown in Figure , the free volume term is dominant in that temperature range. 8 Temperature dependence of χ 1 / r 1 calculated for MMA·iBMA/PiBMA blends with a variety of copolymer composition of iBMA: (a) 0 wt %, (b) 20 wt %, (c) 40 wt %, (d) 60 wt %, and (e) 80 wt %. 9 Temperature dependence of χ 1 / r 1 calculated for MMA·nBMA/PnBMA blends with a variety of copolymer composition of nBMA: (a) 0 wt %, (b) 20 wt %, (c) 40 wt %, (d) 60 wt %, (e) 80 wt %. 10 Temperature dependence of χ 1 / r 1 calculated for MMA·iBMA/PnBMA blends with a variety of copolymer composition of iBMA: (a) 0 wt %, (b) 20 wt %, (c) 40 wt %, (d) 60 wt %, (e) 80 wt %, and (f) 100 wt %. 11 Temperature dependence of χ 1 / r 1 calculated for MMA·nBMA/PiBMA blends with variety of copolymer composition of nBMA: (a) 0 wt %, (b) 20 wt %, (c) 40 wt %, (d) 60 wt %, (e) 80 wt %, and (f) 100 wt %.…”
Section: Resultssupporting
confidence: 62%
“…The values determined thus are shown in column II together with that for PMMA/PnBMA evaluated in the previous work . Column III shows the values of χ, which were extrapolated to 25 °C, obtained from the dependence of miscibility on the copolymer composition at 140−200 °C . As compared in Table , the χ values obtained using the three methods are not so different from one another for each system.…”
Section: Resultsmentioning
confidence: 85%
“…Therefore, polymer blends having UCST-type miscibility have been limited to blends containing random copolymers. , In some random copolymer blends, both the enthalpic interactions and free volume differences may be forced to be small by appropriate combinations of the constituent monomers. In a previous paper we reported that homopolymer blends as well as copolymer blends composed of a series of different methacrylate monomers indicated UCST-type miscibility. In this case, since the constituent monomers have similar chemical structures, small χ values may be realized. 1 Schematic illustration of the temperature dependence of χ: (a and a‘) the enthalpic interaction terms in van der Waals interaction dominant and attractive interaction dominant systems, respectively; (b) the free volume term; and (c and c‘) χ = (a) + (b) and χ = (a‘) + (b), respectively.…”
The Flory interaction parameters χ for blends of random
copolymers consisting of binary
combinations of methyl methacrylate (MMA), n-butyl
methacrylate (nBMA), and isobutyl methacrylate
(iBMA) monomers were calculated using the Flory equation-of-state
theory with modified combining rules
extended to random copolymer systems. In order to determine the
intersegmental or intermolecular
parameters necessary for the calculation of χ for the blends, osmotic
pressures, heats of mixing at infinite
dilution, and excess volumes of mixing for solutions of the
methacrylate random copolymers in
cyclohexanone were measured, and the equation-of-state theory was
applied to these solutions. Using
the intersegmental parameters thereby determined, the theory gives
U-shaped curves for the temperature
dependence of χ for the blends. Namely, the theory shows that
miscibility of these polymer blends is of
the upper critical solution temperature type, which is consistent with
the miscibility results obtained
experimentally in our previous work. The interaction parameters
χ calculated for PiBMA/PnBMA were
much smaller than those for PMMA/PiBMA and PMMA/PnBMA. This result
is also consistent with the
experimental results of miscibility. The calculated χ parameters
were compared with those evaluated
using two other methods, i.e., from the dependence of miscibility on
the copolymer composition of the
random copolymer blends and from the osmotic pressures for the random
copolymer solutions. It was
found that the χ values obtained using all three methods were nearly
the same.
“…A U-shaped curve of χ suggests an occurrence of UCST, as shown in Figure . Namely, the theory shows that thesepolymer blends have UCST-type miscibility, as observed experimentally in the previous work . The slight temperature dependence of χ 1 / r 1 in the high temperature range may be due to a small difference in the free volume because, as shown in Figure , the free volume term is dominant in that temperature range. 8 Temperature dependence of χ 1 / r 1 calculated for MMA·iBMA/PiBMA blends with a variety of copolymer composition of iBMA: (a) 0 wt %, (b) 20 wt %, (c) 40 wt %, (d) 60 wt %, and (e) 80 wt %. 9 Temperature dependence of χ 1 / r 1 calculated for MMA·nBMA/PnBMA blends with a variety of copolymer composition of nBMA: (a) 0 wt %, (b) 20 wt %, (c) 40 wt %, (d) 60 wt %, (e) 80 wt %. 10 Temperature dependence of χ 1 / r 1 calculated for MMA·iBMA/PnBMA blends with a variety of copolymer composition of iBMA: (a) 0 wt %, (b) 20 wt %, (c) 40 wt %, (d) 60 wt %, (e) 80 wt %, and (f) 100 wt %. 11 Temperature dependence of χ 1 / r 1 calculated for MMA·nBMA/PiBMA blends with variety of copolymer composition of nBMA: (a) 0 wt %, (b) 20 wt %, (c) 40 wt %, (d) 60 wt %, (e) 80 wt %, and (f) 100 wt %.…”
Section: Resultssupporting
confidence: 62%
“…The values determined thus are shown in column II together with that for PMMA/PnBMA evaluated in the previous work . Column III shows the values of χ, which were extrapolated to 25 °C, obtained from the dependence of miscibility on the copolymer composition at 140−200 °C . As compared in Table , the χ values obtained using the three methods are not so different from one another for each system.…”
Section: Resultsmentioning
confidence: 85%
“…Therefore, polymer blends having UCST-type miscibility have been limited to blends containing random copolymers. , In some random copolymer blends, both the enthalpic interactions and free volume differences may be forced to be small by appropriate combinations of the constituent monomers. In a previous paper we reported that homopolymer blends as well as copolymer blends composed of a series of different methacrylate monomers indicated UCST-type miscibility. In this case, since the constituent monomers have similar chemical structures, small χ values may be realized. 1 Schematic illustration of the temperature dependence of χ: (a and a‘) the enthalpic interaction terms in van der Waals interaction dominant and attractive interaction dominant systems, respectively; (b) the free volume term; and (c and c‘) χ = (a) + (b) and χ = (a‘) + (b), respectively.…”
The Flory interaction parameters χ for blends of random
copolymers consisting of binary
combinations of methyl methacrylate (MMA), n-butyl
methacrylate (nBMA), and isobutyl methacrylate
(iBMA) monomers were calculated using the Flory equation-of-state
theory with modified combining rules
extended to random copolymer systems. In order to determine the
intersegmental or intermolecular
parameters necessary for the calculation of χ for the blends, osmotic
pressures, heats of mixing at infinite
dilution, and excess volumes of mixing for solutions of the
methacrylate random copolymers in
cyclohexanone were measured, and the equation-of-state theory was
applied to these solutions. Using
the intersegmental parameters thereby determined, the theory gives
U-shaped curves for the temperature
dependence of χ for the blends. Namely, the theory shows that
miscibility of these polymer blends is of
the upper critical solution temperature type, which is consistent with
the miscibility results obtained
experimentally in our previous work. The interaction parameters
χ calculated for PiBMA/PnBMA were
much smaller than those for PMMA/PiBMA and PMMA/PnBMA. This result
is also consistent with the
experimental results of miscibility. The calculated χ parameters
were compared with those evaluated
using two other methods, i.e., from the dependence of miscibility on
the copolymer composition of the
random copolymer blends and from the osmotic pressures for the random
copolymer solutions. It was
found that the χ values obtained using all three methods were nearly
the same.
“…The final properties of the polymer blends depend on the properties of their components, the composition and especially the compatibility of polymers; for most polymer blends is caused by specific interactions [11] , such as dipole-dipole, ion-dipole and hydrogen bonding interactions [12] . In some cases, due to the synergistic effect, the mixtures present better properties than their individual components [13][14][15] .…”
Chitosan/poly(methyl methacrylate-co-butyl methacrylate) (PMMA-co-BMA) blends were prepared via a solution blending method in the presence of formic acid. The compatibility of the bioblends was studied by different methods, such as Fourier transform infrared and Raman spectroscopy, micro-Raman imaging, thermogravimetric analyses, differential scanning calorimetry and scanning electron microscopic analysis. According to the obtained results, it has been concluded that the PMMA-co-BMA/chitosan bioblends are compatible in all the studied compositions. Specific interactions between carbonyl and methyl groups of the PMMAco-BMA structure and methyl, amine and amide groups of chitosan are responsible for the observed compatibility.
INTRODUCTIONConcerns about environmental problems such as global warming, pollution of natural resources, renewable energy use and cost of synthetic polymers have motivated an intense research of sustainable polymer systems where at least one component is biodegradable or biobased [1] . The commercial importance of polymers also have increased the need of discover of new materials with specific properties and applications; for this purpose new polymers have been synthesized and chemical modifications in conventional polymers have also been proposed, but these methods are more complicated [2,3] . However, the mixture of two or more polymers, giving rise to a polymer blend, seems to be an economical method to obtain new polymeric materials with desirable properties, without the need of synthesizes specialized polymer systems [4,5] .
“…Since the χ crit is smaller with increasing molecular weight ( M w) and is negligibly small in a blend of polymers with high molecular weight, UCST type phase behavior occurs only when the χ crit is large in low M w and the positive contribution of the repulsive interaction decreases with increasing temperature ( Figure 1 c). Hence, UCST phase behavior is expected to be uncommon for a blend of polymers with high molecular weights, and it is observed in oligomer blends and random copolymer blends [ 3 , 4 , 5 , 6 , 7 , 8 , 9 ]. UCST type phase behavior is also suggested in crystalline polymer blends [ 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 ].…”
We investigated the structure development and crystallization kinetics in the blends of poly(trimethylene terephthalate) (PTT) and poly(ethylene terephthalate) (PET) by polarized optical microscopy and light scattering. The crystallization of the blend was found to be faster and the size of the spherulites was much smaller than those of the neat component polymers by melt crystallization at low temperature of 180 °C. The discontinuous gap of the crystallization time with temperature was seen in the blends, suggesting phase transition at the temperature Ttr; e.g., the Ttr of the 60/40 PTT/PET was 215 °C. The crystallization was accelerated due to enhancement of the nucleation rate, and interconnected tiny spherulites were obtained at the temperature below the Ttr. The accelerated crystallization and the development of the interconnected structure might be attributed to the liquid-liquid phase separation via spinodal decomposition, due to existence of the upper critical solution temperature (UCST) type phase boundary.
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