Effect of Blend Composition on Scratch Behavior of Polystyrene/Poly(2,6‐dimethyl‐1,4‐phenyleneoxide) Blends

The relationship between the scratch behavior and molecular aggregation states of polystyrene (PS), poly(2,6‐dimethyl‐1,4‐phenyleneoxide) (PPO), and their blends, is investigated based on differential scanning calorimetry (DSC), wide‐angle X‐ray diffraction (WAXD), polarized optical microscopy (POM), and indentation and scratch tests. DSC reveals that all the PS/PPO blends show the single glass transition temperature (T_g) and the T_g monotonically increase and T_g breadth exhibits a maximum, with an increase in PPO content. Furthermore, density and intermolecular chain distance obtained by WAXD exhibits maximum and minimum values at near 50 wt% of PPO, respectively. It is evident that densification occurs by blending PS and PPO. The scratch coefficient of friction (SCOF) value of PS is the largest and PS exhibits a fish‐scale pattern after scratch testing, while the SCOF value of PPO is much smaller than PS and PPO exhibits smooth groove formation. The PS50/PPO50 and PS20/PPO80 blends exhibit superior scratch and indentation resistance than PS and PPO. Damage morphology observation by POM and indentation tests reveals that molecular orientation is more restricted, and resistance against indentation increases for blends. This is due mainly to densification of the blend system.     

Synthesis of Exfoliated Monomer Casting Polyamide 6/Na+‐Montmorillonite Nanocomposites by Anionic Ring Opening Polymerization

Summary: In this work, a novel method using water as a pre‐dispersant of pristine sodium montmorillonite (Na⁺‐MMT) and ε‐caprolactam (CL) monomer was developed for the preparation of exfoliated monomer casting polyamide 6 (MCPA6)/MMT nanocomposites via in situ anionic ring opening polymerization. The dispersion effect of MMT in the MCPA6 matrix was investigated by means of X‐ray diffraction (XRD), as well as transmission electronic microscopy (TEM). The results indicated that nanoscale dispersed MMT was successfully achieved in the MCPA6 matrix. Furthermore, the addition of a small amount of MMT dramatically improved the thermal stability of MCAP6. Analysis using differential scanning calorimetry (DSC) and XRD indicated that nanoscale dispersed MMT sheets acted as heterogeneous nucleation agents, which favored the formation of the γ‐crystalline form of the MCPA6 matrix.

MMT dispersing sketch in the course of polymerization.     

Blends of Immiscible Polystyrene/Polyamide 6 via Successive In‐Situ Polymerizations

Summary: A novel method has been successfully developed to prepare binary blends of PS and MCPA6. The blends are formed by the radical polymerization of styrene in CL, followed by the in‐situ anionic ring‐opening polymerization of CL in the presence of PS. The phase morphology investigated using SEM reveals that PS/MCPA6 blends with a PS content of 10 wt.‐% or lower consists of a MCPA6 matrix and a dispersed PS minor phase. Remarkably, phase inversion occurs in blends that have a PS content of 15 wt.‐% or higher, in which MCPA6 is no longer continuous but finely dispersed in the PS continuous phase. The phase inversion occurs at an extremely low PS content, and this phenomenon is unusual for traditional polymer blends prepared by melt blending. The probable reason for the particular phase morphology development is explained. The stability of the phase morphologies of the PS/MCPA6 blends after annealing at 250 °C is also investigated by SEM.

SEM micrograph of the fractured surface of a PS/MCPA6 blend with a PS content of 20 wt.‐%, in which MCPA6, as spherical particles, is dispersed in the PS continuous phase.     

Effect of Na+‐MMT Platelets on Monomer Casting Polyamide 6/Polyphenylene Oxide Blends

Summary: Blend composites (95:5) of monomer casting polyamide 6 and polyphenylene oxide (MCPA6/PPO) with and without 0.5 wt.‐% Na⁺‐montmorillonite (Na⁺‐MMT) platelets were prepared by in situ AROP of CL using water as a pre‐dispersant of Na⁺‐MMT. The effect of Na⁺‐MMT on morphologies of MCPA6/PPO has been studied by scanning and transmission electron micrographs and rotational rheometer, respectively. The domain size of PPO dispersed phase in the MCPA6 matrix decreased significantly from some dozens of micrometers to about 1 µm and all Na⁺‐MMT was dispersed only in the MCPA6 phase. It is considered that the high aspect ratio of the Na⁺‐MMT prevented the coalescence of PPO domains during in situ polymerization. The results of DSC indicated that the size of PPO dispersed phase affected the crystalline behavior. Synergistic action of PPO and Na⁺‐MMT improved the strength and the toughness of nanocomposites compared with that of the pure MCPA6.

SEM micrographs of the cryo‐fractured surfaces of (A) MCPA6/PPO (95:5) and (B) MCPA6/PPO/Na⁺‐MMT (95:5:0.5).     

New Complex Crystals of Chiral Poly(L‐lactic acid) and Different Tactic Poly(methyl methacrylate)

Based on evidence from differential scanning calorimetry (DSC), wide‐angle X‐ray diffraction (WAXD), and Fourier‐transform infrared (FTIR) spectroscopy, a new stereocomplex crystal (DSC T_m = 175 °C, with WAXD 2θ = 10.0° and 12.5°) is proven for the first time between structurally dissimilar chiral poly(L ‐lactic acid) (PLLA) and syndiotactic poly(methyl methacrylate) (sPMMA). There is a strong complexing capacity only between low molecular weight PLLA and sPMMA, in miscible state, at specific weight fractions (70:30). The complexing capacity is more significant when the mixtures are melt‐crystallized at T_c = 110 °C or lower, and the intensity of this complex can be further enhanced if it is annealed between 100 and 160 °C, below its T_m = 175 °C. The new complex crystal can be formed only between PLLA and sPMMA, but not with isotactic or atactic PMMA.     

Functionalization of LDPE by Melt Grafting with Glycidyl Methacrylate and Reactive Blending with Polyamide‐6

Low‐density polyethylene (LDPE) was functionalized by melt radical grafting with glycidyl methacrylate (GMA) and employed for reactive blending with polyamide‐6 (PA6). The effect of the reaction procedure on the grafting degree of LDPE‐g‐GMA samples (0.5–12.5 wt.‐% GMA) was analyzed as a function of the concentration of GMA monomer, radical initiator (BTP), and addition of styrene as co‐monomer. Optimized grafting conditions were obtained when the amount of the monomer is below 10 wt.‐% and that of peroxide in the range 0.2–0.4 wt.‐%. Binary blends of PA6 with LDPE‐g‐GMA (3.5 wt.‐% GMA) and with LDPE at various compositions (80/20, 67/33, 50/50 wt.‐%) were prepared in an internal mixer and their properties were evaluated by torque, SEM and DSC analyses. Morphological examination by SEM showed a large improvement of phase dispersion and interfacial adhesion in PA6/LDPE‐g‐GMA blends as compared with PA6/LDPE blends. The average diameter of dispersed polyolefin particles was about 0.4 μm for LDPE‐g‐GMA contents < 50 wt.‐%. A marked increase of melt viscosity was observed for the compatibilized blends depending on the concentration of grafted polyolefin, and it was accounted for by the reaction between the epoxy groups of GMA and the carboxyl/amine end‐groups of PA6. The variation of torque was thus related to the molar ratio of reactive group concentration. The analysis of crystallization and melting behavior pointed out marked differences in the phase structure of the blends due to the presence of the functionalized polyolefin. Finally, the in situ formation of a graft copolymer between LDPE‐g‐GMA and PA6 was investigated by means of a selective dissolution method (Molau test) and by FT‐IR and DSC analyses.

SEM micrograph of fracture surface of PA6/LDPE‐g‐GMA 50/50 blend.     

Thermoreversible Supramolecular Organization in Poly(vinylidene fluoride)–Dodecyl Benzene Sulfonic Acid Blends

Blends of poly(vinylidene fluoride) (PVF₂) and dodecyl benzene sulfonic acid (DBSA) were found to phase separate in the melt state from hot‐stage polarizing optical microscopy and differential scanning calorimetry (DSC). Both these studies also indicated the formation of a reversible mesomorphic order in the DBSA‐rich phase of the blends. Scanning electron microscopy (SEM) showed a fibrillar network morphology of the DBSA‐rich phase. Wide‐angle X‐ray diffraction (WAXD) revealed the formation of a lamellar structure in the blends corresponding to a long period of 26 Å. The mesomorphic nature of the blends is believed to arise from the supramolecular organization of the surfactant molecules within the lamella. Thermal study indicated that the supramolecularly organized complex is the VF₂ monomer unit:DBSA ≈ 4:1, and the enthalpy of complexation is ～723 J · mol^?1.

SEM micrograph of a PVF₂‐DBSA blend with weight fraction of DBSA (W_DBSA) = 0.62.     

Isothermal Cold‐Crystallization of PLA/PBAT Blends With and Without the Addition of Acetyl Tributyl Citrate

The isothermal cold‐crystallization kinetics of the PLA phase is studied by DSC and the crystallization from the melt by PLOM. Even though the blends exhibit two phases by SEM, several pieces of evidence indicate that partial miscibility may be present in these blends: small changes in both T_g and T_m of the PLA phase; a dependence of the spherulitic growth rate on blend composition and the oclusion of PBAT droplets inside PLA spherulites. Acetyl tributyl citrate is able to plasticize both phases in the blends, but it displays a preference to dissolve within the PBAT rich phase. There is a synergystic effect on the increase in the overall crystallization rate of the PLA rich phase when both ATBC and PBAT are present in the blend.     

Poly(propylene terephthalate) Modified with 2,2‐Bis[4‐(ethylenoxy)‐1,4‐phenylene]propane terephthalate) Units: Thermal Behaviour,Crystallisation Kinetics and Morphology

Summary: The thermal behaviour of poly(propylene terephthalate) modified with 2,2‐bis[4‐(ethylenoxy)‐1,4‐phenylene]propane terephthalate) units (PPT/BHEEBT copolymers) was investigated by thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and hot‐stage optical microscopy (MO). Good thermal stability was found for each sample. The thermal analysis carried out using the DSC technique showed that the T_m of the copolymers decreased with the increment in BHEEBT unit content. This was different from the T_g which, on the contrary, increased. Wide‐angle X‐ray diffraction measurements allowed the identification of the PPT crystalline structure in each semicrystalline sample. Multiple endotherms were shown in the PPT/BHEEBT samples, due to melting and recrystallisation processes, similarly to PPT. The of the copolymers was derived from the application of the Hoffman‐Weeks' method. The isothermal crystallisation kinetics were analysed according to Avrami's treatment. The introduction of BHEEBT units was found to decrease the crystallisation rate compared to pure PPT. Values of the Avrami's exponent n close to 3 were obtained for PPT/BHEEBT6 and PPT/BHEEBT12, regardless of T_c, in agreement with a crystallisation process originating from pre‐determined nuclei and characterised by three‐dimensional spherulitic growth. As a matter of fact, for these two copolymers, space‐filling spherulites were observed through optical microscopy at all T_cs. The heat of fusion (ΔH_m) was correlated to the specific heat increment (Δc_p) for samples with different degrees of crystallinity, and the results were interpreted on the basis of the existence of an interphase, whose amount was found to depend mainly on composition, despite the thermal treatment applied to the polymer also playing an important role.

Calorimetric curves of PPT, PBHEEBT homopolymers and their random copolymers after melt quenching.     

Enthalpy Relaxation in Poly(4‐hydroxystyrene)/Poly(methyl methacrylate) Blends

Summary: The influence of blend composition on enthalpy relaxation behaviour was assessed for miscible blends of poly(4‐hydroxystyrene)/poly(methyl methacrylate) (PHS/PMMA). Values of enthalpy lost (ΔH(T_a, t_a)) were calculated from experimental data plotted against log₁₀(t_a) and modelled using the Cowie‐Ferguson (CF) semi‐empirical model. This gives a set of values for three adjustable parameters, ΔH_∞(T_a), log₁₀(t_c) and β. The blends relaxed more slowly than PMMA, but more quickly and less co‐operatively than PHS. Moreover, the blends released more enthalpy than PMMA, but less than PHS. The enthalpy lost by the fully relaxed glass (ΔH_∞(T_a)) was less than the theoretical amount possible on reaching the state defined by the liquid enthalpy line extrapolated into the glassy region (ΔH_max(T_a)). Infrared spectroscopy was used for assessing the hydrogen bonding interactions in the blends. The ageing results are discussed with reference to the hydrogen bonding interactions.

Dependence of ΔT (□) and ΔC_p (?) on PHS/PMMA blend composition.     

Functionalization of Shortened Single‐Walled Carbon Nanotubes with Poly(p‐dioxanone) by “Grafting‐From” Approach

Summary: It has been a real challenge to form carbon nanotube (CNT)/polymer composites where CNTs are well‐dispersed in the polymer matrix and the interactions between CNTs and polymers are effectively strong. In this paper, we applied surface‐initiated, ring‐opening polymerization (SI‐ROP) of p‐dioxanone (PDX) to shortened single‐walled carbon nanotubes (s‐SWCNTs) and successfully formed s‐SWCNT/PPDX composites (see Figure). Due to intimate interactions between s‐SWCNTs and PPDX, we observed dramatic changes in PPDX properties upon the formation of the composites: 10%‐weight‐loss‐temperature of PPDX increased by 20 °C (measured by thermogravimetric analysis) and the patterns of T_g and T_m were greatly altered. We did not observe any noticeable peaks from the composite up to 120 °C in differential scanning calorimetry (DSC), while DSC data of PPDX itself showed T_g and T_m at ?13.4 and 103 °C respectively.

Schematic representation of the procedure for formation of s‐SWCNT/PPDX composites.     

Anionic Polymerizations of 1‐Adamantyl Methacrylate and 3‐Methacryloyloxy‐1,1′‐biadamantane

Anionic polymerizations of 1‐adamantyl methacrylate ( 1 ) and 3‐methacryloyloxy‐1,1′‐biadamantane ( 2 ) were carried out in THF at ?50 to ?78 °C for 24 h. The initiator employed was either [1,1‐bis(4′‐trimethylsilylphenyl)‐3‐methylpentyl]lithium ( 3 )/lithium chloride, or diphenylmethylpotassium. The polymerizations of 1 and 2 proceeded quantitatively to afford the polymers having the predicted molecular weights based on the molar ratios of monomers and initiators and the narrow molecular weight distributions (M _w/M _n = 1.05–1.18), indicating the living character of the polymerization systems of 1 and 2 . Novel well‐defined block copolymers, poly[ 2 ‐block‐(tert‐butyl methacrylate)], poly( 2 ‐block‐isoprene‐block‐ 2 ), and poly[[(2,2‐dimethyl‐1,3‐dioxolan‐4‐yl)methyl methacrylate]‐block‐ 2 ], were anionically synthesized by the sequential copolymerization of 2 and comonomers. The poly( 2 ) had the significantly higher glass transition temperature (T_g) of 236 °C and decomposed over 370 °C, while poly( 1 ) started to decompose at around 320 °C before its T_g was reached. This thermal stability can be explained by the substituent effects of the bulky adamantyl and 1,1′‐biadamantyl moieties.

     

Compatibility Studies in Binary Blends of PA6 and ULDPE‐graft‐DEM

In order to study the compatibility promoted in polyamide 6 (PA6) and ultra low‐density polyethylene (ULDPE) blends by grafting polar groups into the ULDPE, several blend compositions were prepared in a twin screw extruder. The grafting agent was diethylmaleate (DEM), and the blend compositions prepared were 0, 20, 50, 80 and 100 wt.‐% of PA6. The compatibility was evaluated by studying the rheological, thermal, morphological, and spectroscopic (infrared and dielectric) properties of the blends. The formation of a copolymer was observed by infrared spectroscopy after selective extraction of the components, presumably by the interaction of terminal NH₂ groups of PA6 and carbonyl groups of ULDPE‐graft‐DEM. Thermal properties showed changes due to compatibilization. For instance, fractionated crystallization of the PA6 component was observed when it formed the dispersed phase in reactive blends in view of the enhanced dispersion. Nucleation of the ULDPE component by the PA6 component was observed for reactive and non‐reactive blends. The DSC melting results showed the presence of two crystalline forms of the PA6 in the blends. These were the less stable γ‐form, predominant over the more stable α‐form, in reactive blends, especially for the 20/80 and 50/50 wt.‐% blend compositions. Dynamic rheological experiments provided data for fitting the Carreau viscosity model; the results revealed that longer characteristic times are obtained for compatibilized systems. This was reinforced by the more elastic behavior that such systems presented in G′‐G″ plots, as compared to the non‐reactive ones. Dielectric spectroscopy revealed a noticeable shifting of the α‐mode of the PA6 to lower temperatures for the 50/50‐g, together with an enhancement of the β over the γ‐mode which indicates the presence of tightly bound water. The T_g depression could be due to the plasticization effect resulting from the substitution of intramolecular PA6 H‐bonds by either water molecules or physical interactions across the interphases.     

Crystallization and Ring‐Banded Spherulite Morphology of Poly(ethylene oxide)‐block‐Poly(ε‐caprolactone) Diblock Copolymer

Summary: The crystallization behavior of crystalline‐crystalline diblock copolymer containing poly(ethylene oxide) (PEO) and poly(ε‐caprolactone) (PCL), in which the weight fraction of PCL is 0.815, has been studied via differential scanning calorimeter (DSC), wide‐angle X‐ray diffraction (WAXD), and polarized optical microscopy (POM). DSC and WAXD indicated that both PEO and PCL blocks crystallize in the block copolymer. POM revealed a ring‐banded spherulite morphology for the PEO‐b‐PCL diblock copolymer.

DSC heating curve for the PEO‐b‐PCL block copolymer.     

Thermoplastic Vulcanizates Based on Highly Compatible Blends of Isotactic Poly(propylene) and Copolymers of Atactic Poly(propylene) and 5‐Ethylidene‐2‐norbornene

Highly compatible thermoplastic/elastomer blends were used to prepare thermoplastic vulcanizates (TPVs) with refined morphologies and improved mechanical properties. Copolymers of atactic poly(propylene) (aPP) and 5‐ethylidene‐2‐norbornene (ENB) (aPP‐co‐ENB) were prepared via metallocene catalysis. Blends of isotactic poly(propylene) (iPP) and the aPP‐co‐ENB rubbers are immiscible in the melt, but the very high compatibility leads to a refinement of the morphology in comparison to blends based on iPP and ethylene‐propylene‐ diene (EPDM) rubber. The aPP‐co‐ENB‐based blends show improved tensile properties, while the relatively high T_g of the rubber phase retards the elastic recovery at room temperature. Dilution of the TPVs with oil broadens the temperature window for applications by a signification reduction of the T_g and improves the elasticity of the TPVs. This study demonstrates that the lower limit of the rubber particle size of TPVs that is attainable via dynamic vulcanization of immiscible blends is in the order of 300–500 nm.

     

Cross‐Linked Poly(ε‐caprolactone/D,L‐lactide) Copolymers with Elastic Properties

Cross‐linked ε‐caprolactone (CL) and D ,L ‐lactide (DLLA) copolymers with elastic properties were synthesized in three steps. First, the monomers were copolymerized in ring‐opening polymerization to obtain telechelic star‐shaped oligomers with almost completely random monomer distribution. The oligomers were methacrylated with methacrylic anhydride in the second step and cured in a third. Molar CL/DLLA compositions of 30/70, 50/50, 70/30, 90/10, and 100/0 were used to obtain elastic structures with a wide range of properties. The effect of the average length of the copolymer block on the properties of the networks was evaluated with three different co‐initiator contents (0.5, 1.0, and 2.0/100) in the oligomer synthesis. The oligomers were characterized by ¹³C NMR spectroscopy, size‐exclusion chromatography (SEC), and differential‐scanning calorimetry (DSC). The formation of elastic networks was confirmed by the absence of a flow region in dynamic mechanical analysis (DMA), the increase in T_g in DSC, and the full recovery of the sample dimensions after tensile testing. In addition, gel contents were high and the samples swelled in CH₂Cl₂. The networks possessed break stresses from 0.7–9.7 MPa with elongations from 80–350%. Networks with 100 or 90% of ε‐caprolactone retained their form in vitro for 12 weeks, but an increase in lactide content made the networks more vulnerable to hydrolysis.

Water absorption of the polymers during hydrolysis.     

Polymorphism in nylon 6/clay nanocomposites

X‐ray diffraction methods and DSC thermal analysis have been used to investigate the structural change of nylon 6/clay nanocomposites. Nylon 6/clay has been prepared by the intercalation of ε‐caprolactam and then exfoliating the layered synthetic saponite by subsequent polymerization. Both X‐ray diffraction data and DSC results indicate the presence of polymorphism in nylon 6 as well as in nylon 6/clay nanocomposites. This polymorphic behavior is dependent on the cooling rate of nylon 6/clay nanocomposites from the melt and on the content of synthetic saponite in nylon 6/clay nanocomposites. The quenching from the melt induces the crystallization into the γ crystalline form. The addition of synthetic saponite may increase the crystallization rate of the α crystalline form at lower synthetic saponite content and promote the heterophase nucleation of γ crystalline form at higher synthetic saponite content. The effect of thermal annealing on the crystalline structure of nylon 6/clay nanocomposites in the range between T_g and T_m is also discussed.     

Ternary Thermosetting Blends of Epoxy Resin,Poly(ethylene oxide) and Poly(ε‐caprolactone)

Summary: The ternary thermosetting blends composed of epoxy resin, poly(ethylene oxide) (PEO) and poly(ε‐caprolactone) (PCL) were prepared via in situ polymerization of epoxy monomers in the presence of the two crystalline polymers, PEO and PCL. DSC results showed that the binary blends of epoxy with PEO (and/or PCL) are fully miscible in the entire composition in the amorphous state. FTIR indicates that there were interchain specific interactions between the crosslinked epoxy and the linear polymers in the binary blends and the hydrogen bonding interactions between epoxy and PCL are much weaker than those between epoxy and PEO. The difference in the strength of interchain specific interactions gives rise to the competitive hydrogen bonding interactions in the ternary blends of epoxy, PEO and PCL, which were evidenced by the results of FTIR. The results of optical microscopy and DSC showed that in the ternary blends PCL component separated out with inclusion of PEO. The formation of the specific phase structures is ascribed to the competitive interchain specific interactions among the crosslinked epoxy, PEO and PCL.

Phase boundary diagram of epoxy, PEO and PCL ternary blends.     

Non‐isothermal Crystallization Kinetics of Biobased Poly(ethylene 2,5‐furandicarboxylate) Synthesized via the Direct Esterification Process

Poly(ethylene 2,5‐furandicarboxylate) (PEF) is an emergent biobased polyester whose chemical structure is analogous to poly(ethylene terephthalate). Pilot‐scale PEF is synthesized through the direct esterification process from 2,5‐furandicarboxylic acid and bio‐ethylene glycol. Wide‐angle X‐ray diffraction (WAXD) measurements reveal similar crystallinities and unit cell structures for melt‐crystallized and glass‐crystallized samples. The non‐isothermal crystallization of PEF sample is investigated by means of DSC experiments both from the glass and the melt. The temperature dependence of the effective activation energy of the growth rate is obtained from these data, and the results show that the glass and early stage of the melt crystallization share common dynamics. Hoffman–Lauritzen parameters and the temperature at maximum crystallization rate are evaluated. It is found that the melt‐crystallization kinetics undergo a transition from regime I to II; however, the crystal growth rate from the melt shows an atypical depression at T < 171 °C compared with the predicted Hoffman–Lauritzen theory.

     

Thermophysical Properties and Molecular Relaxations in Cured Epoxy Resin + PEO Blends: Observations on Factors Controlling Miscibility

Summary: Thermophysical properties and molecular relaxations in aromatic amine‐cured diglycidyl ether of bisphenol‐A (DGEBA) epoxy oligomer and poly(ethylene oxide) (PEO) mixtures were determined by DSC and dielectric techniques (TSC, DRS). The binary blends were judged to be fully miscible in the amorphous state (w_PEO < 40 wt.‐%), as evidenced by the single composition‐dependent glass transition temperatures T_gs. In the amorphous blends, negative deviations of dielectric/thermal T_g‐estimates from the linear mixing rule or the behavior predicted by the Fox equation reveal weaker intermolecular interactions, compared to strong self‐association of hydroxyls in the cured thermoset. Morphological changes in PEO‐rich blends (w_PEO ≥ 40 wt.‐%) are in accordance with their complicated interface structure, previously reported to consist of amorphous PEO regions, branched epoxy resin chains and an imperfect epoxy resin network located between PEO lamellae. In these blends, PEO crystallites exert steric hindrances in the amorphous regions, causing strong T_g upshifts. Changes in the relaxation dynamics of glyceryl segments (e.g., in the activation energy barrier and relaxation strength) are in accordance with the idea that the close matching between the molecular polarities of PEO, epoxy resin and the cure agent significantly contributes to the observed miscibility.

Plots of transition temperatures as function of blend composition.