Segmental Interaction Parameters Research Articles

Phase behaviour of blends of poly(methyl methacrylate) with poly(stryene- co-methacrylonitrile)

The phase behaviour of blends of poly(methyl methacrylate) (PMMA) with poly(styrene- co-methacrylonitrile) (SMAN) was investigated using differential scanning calorimetry. PMMA is miscible with SMAN having methacrylonitrile (MAN) contents between 8 and 63 wt%. The miscibility range is wider than that of PMMA/poly(styrene- co-acrylonitrile) blend system, and is in good agreement with that predicted using a non-hydrogen-bonded solubility parameter approach. Segmental interaction parameters involving MAN are smaller than corresponding parameters involving acrylonitrile.

Miscibility in Copolymer Blends of Poly(vinyl chloride-co-vinyl acetate) and Poly(methyl-co-hexyl acrylate)

The phase behavior in 50/50 wt% binary random copolymer blends of poly(vinyl chloride-co-vinyl acetate) and poly(methyl-co-hexyl acrylate) was studied. The blends had a miscibility window and exhibited LCST behavior. The miscibility was determined as a function of composition of each copolymer and displayed in composition-composition diagram [C-C diagram]. The segmental interaction parameters between monomer units comprising the blends were calculated by applying the mean field theory expression to the C-C diagram. Using the segmental interaction parameters, blend interaction parameters which represent the miscibility of the blend system quantitatively, were also estimated. From the calculated values, it was found that the segmental interactions of vinyl acetate unit with other units were strongly repulsive and had significant effect on the miscibility.

Prediction of miscibility regions in ternary blends of poly(styrene‐stat‐acrylonitrile), poly(acrylonitrile‐stat‐methyl methacrylate), and poly(styrene‐stat‐methyl methacrylate)

AbstractThe miscibilities of ternary copolymer blends prepared from poly(styrene‐stat‐acrylonitrile), poly(styrene‐stat‐methyl methacrylate), and poly(methyl methacrylate‐stat‐acrylonitrile) were predicted by calculating the interaction parameter, χblend, for various blend combinations, from the corresponding binary segmental interaction parameters estimated from previous work. Binodal and spinodal curves were calculated using the Flory‐Huggins theory and it was observed that the most accurate estimate of the boundary between miscible and immiscible blends was given by the spinodal. It has also been demonstrated that in some of the ternary blends with fixed copolymer compositions the miscibility of the blend can be altered by changing the ratio of the three components in the mixture. Conditions for miscibility in this ternary system, and possibly a general feature of all such systems, are (a) that at least two of the binary interaction parameters χij are less than the critical value χcrit, while the third should not be too much larger, that is, one of the copolymers may act as a compatibilizer for the other two copolymers, (b) that the difference Δχ = /χ12 − χ13/ is small. © 1992 John Wiley & Sons, Inc.

Miscibility of poly(tetrahydrofurfuryl methacrylate) with poly(styrene-co-acrylonitrile) and poly( p-methylstyrene-co-acrylonitrile)

The miscibility behaviour of poly(tetrahydrofurfuryl methacrylate) (PTHFMA) with poly(styrene-co-acrylonitrile) (SAN) and poly( p-methylstyrene-co-acrylonitrile) ( pMSAN) has been studied. PTHFMA is miscible with SAN having AN contents between 9 and 48 wt% and with pMSAN having AN contents between 12 and 48 wt%. Using the binary interaction model, segmental interaction parameters ξ THFMA/S and ξ TFHMA/ pMS are found to be 0.036 and 0.050, respectively. The ξ THFMA/AN values are 0.42 and 0.44 evaluated from SAN and pMSAN systems, respectively.

Miscibility of tetramethylbisphenol-A polycarbonate with poly(styrene-co-tetrahydrofurfuryl methacrylate) and with poly( p-methylstyrene-co-tetrahydrofurfuryl methacrylate)

The miscibility of tetramethylbisphenol-A polycarbonate (TMPC) with poly(styrene-co-tetrahydrofurfuryl methacrylate) (STHFMA) and with poly( p-methylstyrene-co-tetrahydrofurfuryl methacrylate) (MSTHFMA) was studied. TMPC is miscible with STHFMA having THFMA content less than 50 mol% and with MSTHFMA having THFMA content less than 53 mol%. On the basis of the miscibility behaviour of the blends and also blends of TMPC with poly(styrene-co-acrylonitrile) reported by Fernandes et al., various segmental interaction parameters have been evaluated.

Structure of symmetric polyolefin block copolymer thin films

The microstructure of thin films of nearly symmetric poly(ethylene–propylene)–poly(ethylethylene) (PEP-PEE) diblock copolymers (f=0.55, where f is the volume fraction of PEP) was characterized by neutron reflectometry (NR). A symmetric film structure in which the PEE block segregates preferentially to both interfaces is observed above and below the bulk order–disorder transition (ODT). Measurements at room temperature for several chain lengths, N, provide a real-space picture of the change in interdomain interfacial profiles associated with the crossover between the strong and weak segregation limits. The polymer/air and substrate/polymer interfaces are observed to induce an ordered microstructure even when the center of the film is disordered. The characteristic dimension of this near surface microstructure is larger than the corresponding bulk value for values of χN lying between those of the bulk Gaussian-to-stretched-coil and order–disorder transitions, where χ is the segment–segment interaction parameter. This behavior is attributed to the correlation of large amplitude composition fluctuations in the film with the interfaces. A mean-field behavior prevails for χN<(χN)GST,bulk, where some preferential segregation occurs at the interfaces, but the characteristic dimension once again matches that in the bulk.

Evaluation of segmental interaction by small-angle x-ray scattering based on the random-phase approximation for asymmetric, polydisperse triblock copolymers

The binary segmental interaction parameter, χ S-B , for poly(styrene-block-butadiene-block-styrene) (SBS) was evaluated by analyzing the SAXS in the disordered state based on the random-phase approximation (RPA) for asymmetric and polydisperse triblock copolymers. The parameter fitting allowed us to determine also the radius of gyration, R g , of an entire copolymer from the peak position of the scattered intensity. The effects of asymmetry in the size of the repeating units and polydispersity on the scattering function and on the evaluation of χ and R g for SBS samples were studied

Application of segmental interaction energies to miscibility prediction in binary and ternary copolymer solid solutions

AbstractMany binary polymer mixtures, where at least one of the components is a copolymer, are capable of forming miscible blends within certain restricted ranges of compositions of the copolymers. The segmental interaction parameters χij can be determined from many of these systems when the phase boundaries are established, and can be used to predict miscibility in other blends. Determination of χij parameters is illustrated for a number of different copolymer mixtures and the ability to predict and map the miscibility regions in other blends is demonstrated. The technique has been extended to ternary copolymer systems with satisfactory results.

Blends of poly(styrene-ran- p-nitrostyrene) with poly(vinyl methyl ether) and poly(2,6-dimethyl- p.phenylene oxide)

Poly(styrene-ran- p.nitrostyrene) was synthesized by direct nitration of polystyrene to give copolymer samples of various nitro contents. The miscibilities of these samples with themselves (internal miscibility), with poly(vinyl methyl ether) and with poly (2,6-dimethyl- p.phenylene oxide) were determined by examining the glass transitions of their blends. Lower critical solution temperatures were found for the (styrene-nitrostyrene) + vinyl methyl ether blends. The various segmental interaction parameters, B ij, were obtained by analysis of the phase behaviour.

Miscibility behavior in blends of poly(acrylonitrile-co-butadiene) and chlorinated poly(vinyl chloride)

The miscibility and phase behavfiour in 50:50 wt % blends of chlorinated PVC (CPVC) and poly(acrylonitrile-co-butadiene) (AN-BT) were studied. The miscibility-immiscibility boundary at 150°C was determined. It was found that the extent of miscibility of this system becomes larger with increasing chlorine content of CPVC, compared to that of the PVC/(AN-BT) system. By assuming a random copolymer structure and applying the first-order mean field theory to the results , the respective segmental interaction parameters were determined. The theoretical phase boundary is consistent with experimental data.

Miscibility of poly(methoxymethyl methacrylate) and poly(methylthiomethyl methacrylate) with poly(styrene‐co‐acrylonitrile) and poly(p‐methylstyrene‐co‐acrylonitrile)

AbstractThe miscibility of poly(methoxymethyl methacrylate) (PMOMA) and poly(methylthiomethyl methacrylate) (PMTMA) with poly(styrene‐co‐acrylonitrile) (SAN) and poly(p‐methylstyrene‐co‐acrylonitrile) (pMSAN) was studied by differential scanning calorimetry. PMOMA is miscible with SAN having an acrylonitrile (AN) content around 30 wt %. However, PMOMA is immiscible with any of the pMSAN having AN contents between 9 and 36 wt % and with pMSAN having AN contents between 19 and 34 wt %. The miscibility of the blends enables the evaluation of various segmental interaction parameters.

Observation of restricted miscibility in binary blends of poly(styrene- stat-acrylonitrile) and poly(α-methyl styrene- stat-acrylonitrile)

Binary blends of two structurally similar copolymers poly(styrene- stat-acrylonitrile) and poly(α-methyl styrene- stat-acrylonitrile) were examined by differential scanning calorimetry. A miscibility map constructed for the system showed that the miscibility range was quite restricted and had a significant molecular weight dependence. The system was characterized by using segmental interaction energy densities calculated from earlier work and it was found that a satisfactory description of the miscibility range could only be obtained if a distinction was made between the ‘intra’ and ‘inter’ segmental interaction parameters. This sensitivity of the interchange energy to the environment of the segment has been observed in other systems. Consequently it may be an important feature in blends whose miscibility ranges are strongly molecular weight dependent, whereas in less sensitive blends the approximation B ij (inter) = B ij (intra) is adequate.

Phase behaviour of blends of poly(acetonyl methacrylate) with poly(styrene- co-acrylonitrile) and poly( p-methylstyrene- co-acrylonitrile)

The miscibility of poly(acetonyl methacrylate) (PACMA) with poly(styrene- co-acrylonitrile) (SAN) and poly( p-methylstyrene- co-acrylonitrile) ( pMSAN) has been studied by differential scanning calorimetry. PACMA is miscible with SAN having acrylonitrile (AN) contents between 33 wt% and 58 wt% and with pMSAN having AN contents between 43 wt% and 61 wt%. Three segmental interaction parameters, χ ACMA S , χ ACMA pMS and χ ACMA AN , were found to be 0.15, 0.22 and 0.24, respectively. The results obtained for PACMA are compared to those of poly(n-propyl methacrylate) and poly(isopropyl methacrylate). The miscibility behaviour is discussed in terms of the binary interaction model as well as the non-hydrogen-bonded solubility parameter concept.

Phase behaviour of blends of poly(tetrahydropyranyl-2-methyl methacrylate) with poly(styrene- co-acrylonitrile) and poly( p-methylstyrene- co-acrylonitrile)

The miscibility of poly(tetrahydropyranyl-2-methyl methacrylate) (PTHPMA) with poly(styrene- co-acrylonitrile) (SAN) and poly( p-methylstyrene- co-acrylonitrile) ( pMSAN) has been studied by differential scanning calorimetry. PTHPMA is miscible with SAN having an acrylonitrile (AN) content between 0 wt% and 31 wt%, and with pMSAN having an AN content between 5 wt% and 29 wt%. Three segmental interaction parameters, χ THPMA S , χ THPMA pMS and χ THPMA AN , were found to be −0.011, 0.019 and 0.64, respectively.

Miscibility and phase behavior in atactic polystyrene and poly(o‐chlorostyrene‐co‐p‐chlorostyrene) blends: Effect of polystyrene molecular weight and copolymer composition

AbstractMiscibility in blends of random copolymers of o‐chlorostyrene and p‐chlorostyrene [P(oClSy‐co‐pClS1‐y)] with 8 atactic polystyrene (aPS) fractions has been studied at temperatures ranging from 150°C to 300°C. Miscibility windows whose size depends on the molecular weight of the PS and on the copolymer composition, y, were observed for each blend. From these data, the temperature dependence of the three segmental interaction parameters required to describe this system were obtained.

Miscibility of poly(vinyl chloride) with poly(methyl‐co‐hexyl acrylate) and poly(methyl‐co‐2 ethyl hexyl acrylate)

AbstractThe miscibility and phase behavior in blends of PVC with poly(methyl‐co‐hexyl acrylate)[MHA] and poly(methyl‐co‐2 ethyl hexyl acrylate)[MEH] were studied. It was found that PVC is miscible with MHA copolymers having a HA volume fraction from 0.30 to 0.92 and MEH copolymers having an EH volume fraction from 0.30 to 0.83 at 100°C. By applying the mean field theory to the phase diagrams of these blend systems, segmental interaction parameters which represent the binary interaction between different monomer units were estimated. The calculated values reflect the fact that the miscibility window observed for PVC/MHA and PVC/MEH blend systems was attributed to the effect of repulsion between different monomer units within the copolymer. To investigate the effect of specific interaction on the miscibility for these blend systems, an attempt was also made to describe the blend interaction parameter as a function of polar group concentration in the acrylate copolymer. The blend interaction parameter values exhibit a u‐shaped curve as a function of the weight fraction of CO group in the copolymer, and the lowest blend interaction parameter value appears at about 0.24 CO weight fraction.

Miscibility of Poly(vinylidene fluoride) and Poly(styrene-co-methyl methacrylate) Blends

The miscibility of poly(vinylidene fluoride) (PVDF) and poly(styrene-co-methyl methacrylate) (SMMA) blends was examined as a function of copolymer composition. PVDF was miscible with SMMA copolymers having an styrene content less than 13 vol%. The segmental interaction parameters were determined by combining the equilibrium melting point depression of PVDF and the binary interaction model. According to the binary interaction model, the maximum styrene content in SMMA for the blend to be miscible was predicted as 18.5 vol% which agrees well with an experimental result.

Miscibility of poly(phenyl acrylate) with acrylonitrile/styrene copolymers

The Blase transition and phase behavior of blends of poly(pheny1 acrylate) with poly(acrylonitri1eco-styrene) was studied by differential scanning calorimetry. It was found that poly(pheny1 acrylate) is miscible with poly(acrylonitri1e-co-styrenes) within a specific range of copolymer composition. The segmental interaction parameters were estimated and found to be positive for all three pairs. The miscibility in thissystem appears to be the consequence of the intramolecular repulsion between styrene and acrylonitrile units.

Miscibility of poly(2-chloroethyl methacrylate) with poly(styrene-co-acrylonitrile) and poly( p-methylstyrene-co-acrylonitrile)

The miscibility and lower critical solution temperature behaviour of blends of poly(2-chloroethyl methacrylate) (PCEMA) with poly(styrene-co-acrylonitrile) (SAN) and poly( p-methylstyrene-co-acrylonitrile) ( pMSAN) have been studied. PCEMA is miscible with SAN having acrylonitrile (AN) contents between 12.5 and 43 wt% and with pMSAN having AN contents between 18.3 and 46 wt%. The miscibility of the blends is explained by the binary interaction model; the various segmental interaction parameters were evaluated.

Miscibility of poly(2-bromoethyl methacrylate) with poly(styrene-co-acrylonitrile) and poly( p-methylstyrene-co-acrylonitrile)

The miscibility behaviour of poly(2-bromoethyl methacrylate) (PBEMA) with poly(styrene-co-acrylonitrile) (SAN) and poly( p-methylstyrene-co-acrylonitrile) ( pMSAN) was investigated using differential scanning calorimetry. PBEMA is miscible with SAN having acrylonitrile (AN) contents between 10 and 58 wt% and with pMSAN having AN contents between 14 and 61 wt%. The miscibility of these blends was explained by the binary interaction model and the various segmental interaction parameters were evaluated.