Phase diagrams of blends of azide-containing polyoxetanes

The mutual solubility of polymers based on the azide-containing oxetane monomers 3,3-bis(azidomethyl)oxetane and 3-azidomethyl-3-methyloxetane is studied. The temperatures of melting, crystallization, glass transition; the upper critical solution temperature; and the compositions of coexisting phases for blends of polymers with different molecular masses are determined via differential scanning calorimetry and multiple-beam microinterferometry. On the basis of these data, the phase diagrams of blends are constructed. The melting regions and the metastable and heterogeneous states are determined. The studied systems are shown to have a complex amorphous-crystalline equilibrium and to differ in the location of boundary curves on the phase diagram, depending on the molecular mass of the components. Amorphous separation below the liquidus line in the metastable region with respect to the crystalline equilibrium is experimentally detected. The motion of the figurative point in different regions of the diagram is thoroughly considered. The specifics of structural and morphological organization of systems are examined via electron microscopy.     

Miscibility Behaviour of Poly(ether Sulphone)/nylon-6 Blends

Binary blends of poly (ether sulphone) (PES) and Nylon-6 were prepared in a whole range of composition by melt extrusion. Miscibility behaviour of the blends were studied using thermal analytical techniques like differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA). Due to the rapid crystallization of Nylon-6 as it is cooled from the melt state, its glass transition behaviour could not be detected even in the quenched samples by DSC. Furthermore, the crystallization and melting behaviour of the blends have been studied by DSC. DMA results show that the dynamic storage modulus of the blends were in-between those of the constituent polymers. Also the glass transition of Nylon-6 phase as determined by the peak in loss tangent remains constant which shows that the two polymers are immiscible. Thermal expansion coefficient of the blends as determined by TMA is greater than that of Nylon-6 signifying the increased dimensional stability of the blends at higher temperatures. Morphological studies done by scanning electron microscopy (SEM) show the biphasic nature of the blends, with clear cut boundaries between the phases because of poor interfacial adhesion. Dispersed particle size is small when Nylon-6 is the dispersed phase because of its lower melt viscosity as compared to PES. Thermal stability of the blends was measured using thermogravimetric analysis (TG). Two-step decomposition behaviour was observed because of macro-phase separated morphology. This revised version was published online in July 2006 with corrections to the Cover Date.     

Miscibility,Crystallization, and Rheological Behavior of Solution Casting Poly(3-hydroxybutyrate)/poly(ethylene succinate) Blends Probed by Differential Scanning Calorimetry,Rheology, and Optical Microscope Techniques

The miscibility and crystallization of solution casting biodegradable poly(3-hydroxybuty-rate)/poly(ethylene succinate) (PHB/PES) blends was investigated by differential scanning calorimetry, rheology, and optical microscopy. The blends showed two glass transition temperatures and a depression of melting temperature of PHB with compositions in phase diagram, which indicated that the blend was partially miscible. The morphology observation supported this result. It was found that the PHB and PES can crystallize simultaneously or upon stepwise depending on the crystallization temperatures and compositions. The spherulite growth rate of PHB increased with increasing of PES content. The influence of compositions on the spherulitic growth rate for the partially miscible polymer blends was discussed.     

Equilibrium Crystallization Temperature of Syndiotactic Polystyrene <Emphasis Type="Italic">γ</Emphasis> Form

The crystallization behavior of syndiotactic polystyrene (sPS) γ form undergoing annealing at various temperatures was investigated using the thermodynamic phase diagram based on Strobl's crystallization theory.On the basis of the differential scanning calorimetric results,it was observed that γ form melt-recrystallization occurred at a higher temperature with the increasing lamellar thickness,which resulted from the pre-annealing at the elevating temperature after acetone induced crystallization.Further temperature dependent small-angle X-ray scattering (SAXS) measurement revealed the evolution of the γ form lamellae upon heating until phase transition,involving three different regimes:lamellae stable region (25-90 ℃),melt-recrystallization region (90-185 ℃) and pre-phase transition region (185-195 ℃).As a result,recrystallization line,equilibrium recrystallization line and melting line were developed for the sPS γform crystallization process.Since the melt of γform involved a γto-α/β form phase transition,the melting line was also denoted as the phase transition line in this special case.Therefore,the equilibrium crystallization temperature and melting (phase transition)temperatures were determined at around 390 and 220 ℃ on the basis of the thermodynamic phase diagram of the sPS γform.     

A DSC study of miscibility and phase separation in crystalline polymer blends of phenolphthalein poly(ether ether sulfone) and poly(ethylene oxide)

The miscibility of blends of phenolphthalein poly(ether ether sulfone) (PES-C) and poly(ethylene oxide) (PEO) was established on the basis of the thermal analysis results. Differential scanning calorimetry (DSC) studies showed that the PES-C/PEO blends prepared by casting from N,N-dimethylformamide (DMF) possessed a single, composition-dependent glass transition temperature (T_g), and thus that PES-C and PEO are miscible in the amorphous state at all compositions at lower temperature. At higher temperature, the blends underwent phase separation, and the PES-C/PEO blend system was found to display a lower critical solution temperature (LCST) behavior. The phase separation process in the blends has also been investigated by using DSC. Annealed at high temperatures, the PES-C/PEO blends exhibited significant changes of thermal properties, such as the enthalpy of crystallization and fusion, temperatures of crystallization and melting, depending on blend composition when phase separation occurred. These changes reflect different characteristics of phase structure in the blends, and were taken as probes to determine phase boundary. From both the thermal analysis and optical microscopy, the phase diagram of the blend system was established. © 1997 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 35 : 1383–1392, 1997     

交联对聚己二酸乙二醇酯聚氨酯/甲基丙烯酸甲酯交联聚合物的力学阻尼、相容性及形态的影响

 用紫外光聚合方法制备出一系列端乙烯基聚己二酸乙二醇酯聚氨酯(PEAPU)和甲基丙烯酸甲酯(MMA)AB交联聚合物(ABCP)。用粘弹谱仪、透射电子显微镜(TEM)和平衡溶胀法研究了AB交联聚合物的动态力学性能、玻璃化转变温度、形态和交联密度、观察到相应于聚氨酯和PMMA相两个玻璃化转变温度,TEM照片中的微相分离是更明显的,ABCP中的两个T_g内移表明,两种成分的化学交联增加了相互的可混性、与ABCP具有相同组成的IPN有比ABCP大得多的相区。氢键能够影响ABCP的相容性、形态和动态力学性能。     

交联对聚己二酸乙二醇酯聚氨酯/甲基丙烯酸甲酯交联聚合物的力学阻尼、相容性及形态的影响

用紫外光聚合方法制备出一系列端乙烯基聚己二酸乙二醇酯聚氨酯(PEAPU)和甲基丙烯酸甲酯(MMA)AB交联聚合物(ABCP)。用粘弹谱仪、透射电子显微镜(TEM)和平衡溶胀法研究了AB交联聚合物的动态力学性能、玻璃化转变温度、形态和交联密度、观察到相应于聚氨酯和PMMA相两个玻璃化转变温度,TEM照片中的微相分离是更明显的,ABCP中的两个T_g内移表明,两种成分的化学交联增加了相互的可混性、与ABCP具有相同组成的IPN有比ABCP大得多的相区。氢键能够影响ABCP的相容性、形态和动态力学性能。     

Blends of some non-flexible and flexible polymers: Routes to molecular composites?

The definition of a molecular composite is a blend of a rigid rod polymer and a flexible coil polymer that is miscible at the molecular level. This concept has been tested using systems in which the chain flexibilities differ as widely as possible as judged by the difference in glass transition temperatures (δTg). The biggest variation (δT ∼360°C) was obtained by mixing poly benzimidazole with copolymers of poly(vinyl acetate-ran-vinyl alcohol). It was observed that the blends were distinctly two phase when the hydroxyl content was less than 50 mol %. Above this value clear blends were obtained with finely dispersed phases although it is doubtful if mixing at the molecular level takes place. Miscible blends could be obtained from combinations of the sodium salt of poly(phenylene terephthalamide) with poly(4-vinylpyridine) and mixtures of poly(phenyl imino-1,4-phenyleneoxyterephthalate) with poly(styrene-stat-hydroxylstyrene) where coulombic interactions and hydrogen bonding respectively promoted the miscibility.     

聚L-乳酸/4,4'-二羟基二苯硫醚共混物的分子间相互作用及结晶和熔融行为

利用红外吸收光谱(FTIR)研究了聚乳酸(PLLA)/4,4'-二羟基二苯硫醚(TDP)熔融共混物的分子间相互作用,结果表明,PLLA的羰基与TDP的羟基之间形成了分子间氢键.通过差示扫描量热(DSC)研究了共混物的玻璃化转变行为及非等温结晶和熔融行为.结果表明,样品的玻璃化转变温度(Tg)随TDP含量的增加呈线性下降.共混物的熔融结晶温度(Tc)、结晶焓(ΔHc)、熔融温度(Tm)及熔融焓(ΔHm)均随TDP含量的增加呈下降趋势,而冷结晶温度的变化趋势则相反.当TDP达到40%(质量分数)时,共混物的DSC曲线既未出现结晶峰,也未出现熔融峰,表明该样品已完全成为非晶态物质.广角X射线衍射(WAXD)分析结果表明,TDP的加入未改变PLLA的晶型,但导致其晶面间距变大,晶体结构变得松散.因此共混物熔点的下降归因于分子间氢键的形成降低了PLLA分子链的运动能力及晶体的紧密程度而非晶型的改变.     

聚环氧乙烷(PEO)与聚醋酸乙烯酯(PVA)的共混研究

动态力学谱研究表明熔融共混PVA/PEO体系的无定形态中存在着纯PEO及PVA/PEO的相容或部分相容相。相容或部分相容相的T_g随共混物组成的变化远高于按照FOX方程的计算值。用结晶和分子间相互作用解释了这种对FOX方程的偏离。应用FTIR差示光谱技术对PVA/PEO共混物和PVA/DGDE浓溶液的研究证实了PVA分子链上酯基和PEO分子链存在着强的相互作用。     

Polymer blends of sPS/PA6 compatibilized by sulfonated syndiotactic polystyrene

Syndiotactic polystyrene (sPS) and polyamide-6 (PA6) are immiscible and incompatible and have been recognized. In this study, sulfonated syndiotactic polystyrene (SsPS-H) is employed as compatibilizer in the blend of sPS/PA6. During melt blending, the sulfonic acid groups of the SsPS-H can interact strongly with the amine end-groups of PA6 through acid-base interaction. In addition, SsPS-H is miscible with sPS when SsPS-H content is less than 20 wt.%. Therefore, the addition of SsPS-H to sPS/PA6 blends reduces the dispersed phase size and improves the adhesion between the phases. The glass transition temperatures of the PA6 component in the compatibilized blends shift progressively towards higher temperature with the content of SsPS-H-12 increase, indicating enhanced compatibility. On the other hand, the progressive lowering of the melting point and crystallization temperatures of PA6 in the blends with increasing SsPS-H contents compared to the incompatibilized blend, provide some insight into the level of interaction between the PA6 and SsPS-H. The compatibilized blends have significantly higher impact strength than the blends without SsPS-H. The best improvement in the impact strength of the blends was achieved with the content of the SsPS-H (11.9 mol%) about 5 wt.%.     

Molecular mobility of the paracetamol amorphous form

The purpose of this paper is to study the molecular mobility of paracetamol molecules in their amorphous state below the glass transition temperature (Tg) in order to evaluate the thermodynamic driving force which allows the amorphous form to recrystallize under different polymorphic modifications. Samples were aged at temperatures of -15, 0, 6, and 12 degrees C for periods of time from 1 h to a maximum of 360 h. The extent of physical aging was measured by a DSC study of enthalpy recovery in the glass transition region. The onset temperature of glass transition was also determined (Tg). Enthalpy recovery (deltaH) and change in heat capacity (deltaCp) were used to calculate the mean molecular relaxation time constant (tau) using the empirical Kohlausch-Williams-Watts (KWW) equation. Enthalpy recovery and onset glass transition temperature increased gradually with aging and aging temperatures. Structural equilibrium was reached experimentally only at an aging temperature of 12 degrees C (Tg-10 degrees C), according to the deltaH(infinity) results. The experimental model used is appropriate only at lower aging temperatures, while at higher ones the complexity of the system increases and molecular polymorphic arrangement could be involved. When structural equilibrium is experimentally reached, molecules can be arranged in their lowest energy state, and the polymorphic form I formation is the one preferred.     

共混方法对聚氯乙烯/聚丙撑碳酸酯相容性影响

本文分别用溶液法和熔融法制得聚氯乙烯（PVC）与聚丙撑碳酸酯（PPC）共混试样，用DSC证明PVC／PPC共混物不相容，但它们不相容的程度受分子量、共混比例等因素的影响，并根据玻璃化转变温度（Tg）计算出溶液共混试样PPC富相中PVC的重量百分含量。NBR／PPC弹性体作偶联剂对PVC／PPC共混体系具有较好的增容作用，共混物中PPC的用量及分子量对共混体系性能有一定的影响。     

Interrelation between phase state and gas permeation in polysulfone/polyimide blend membranes

The phase state of polysulfone/polyimide (PSF/PI) blends has been studied by differential scanning calorimetry, rheology, and X-ray scattering. The blends rich in PSF form miscible blends when prepared by solution casting from a common solvent. In these PSF-rich blends, the single dynamic process in rheology shifts and broadens, with composition reflecting the change in local friction and the enhancement of concentration fluctuations, respectively. Heating to temperatures above the glass transition temperature results in phase separation into PSF- and PI-rich domains. An apparent phase diagram has been constructed, and helium permeability has been measured in different regimes corresponding to miscible, partially miscible, and completely phase-separated states. We find that one component (PI) controls the permeability values and activation energies for helium permeation in the blends. Gas permeation is found to be very sensitive to local concentration fluctuations and thus can be used as a probe of the phase state in polymer blends. © 1999 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 37: 2788–2798, 1999     

Poly(ε-caprolactone) + unsaturated isophtalic polyester blends: Thermal properties and morphology

Miscibility of blends composed by a linear unsaturated polyester (LUP) with poly(ε-caprolactone) (PCL) of different molecular weights (M_w = 50 × 10³, 18 × 10³ and 2 × 10³) has been studied. The blends were subjected to different thermal treatments and have been studied by FT-IR spectroscopy, differential scanning calorimetry (DSC) and scanning electronic microscopy (ESEM). FT-IR results allow proving the miscibility of the blends at temperatures above the melting temperature of neat PCL. DSC measurements confirm the existence of a crystalline phase corresponding to neat PCL. The crystallization of PCL is observed in a wide range of blends composition, being detected in all the blend compositions when the crystallization time increases. Thermograms show clearly the glass transition temperatures of samples that have been rapidly quenched from the melt. However, the change in the heat flow corresponding to the glass transition temperatures is difficult to detect in samples with high PCL crystallization degree. The analysis of the results indicates that the morphology of the amorphous phase is heterogeneous for LUP + PCL blends and changes depending on the thermal treatment. The ESEM measurements, confirm the heterogeneity of the amorphous phase. The decrease of the molecular weight of the PCL favours the miscibility of the blends.     

Relations between Glass Transition Temperatures in Miscible Polymer Blends and Composition: From Volume to Mass Fractions

The use of volume fractions in the empirical mixing laws to predict the glass transition temperatures (Tg) of polymer blends provides good agreement with experimental values, even for polymer systems with different densities. No adjustment parameter is therefore required whereas Gordon-Taylor and Kwei equations based on weight fractions need the use of a fitting parameter which has to be determined from experimental data. This assumption was validated from Tg measurements through DSC experiments conducted on PMMA /PVDF blends which have significantly different densities.     

不同结晶度的乙二醇及其水溶液玻璃化转变与焓松弛

为了考察晶体成分对无定形成分玻璃化转变和结构松弛行为的影响,利用差示扫描量热法(DSC),结合低温显微技术,研究了乙二醇(EG)及其50％水溶液在不同结晶度时的玻璃化转变和焓松弛行为.采用等温结晶方法控制骤冷的部分结晶玻璃体中的晶体份额.DSC结果表明,对于部分结晶的EG,只有单一的玻璃化转变过程,而对于50％EG,当结晶度不同时,不同程度地表现出两次玻璃化转变（无定形相Ⅰ和无定形相Ⅱ）.相Ⅰ的玻璃化转变温度和完全无定形态的含水EG的玻璃化转变温度相一致;相Ⅱ的玻璃化转变温度要比此温度约高6 ℃.低温显微观察结果印证了DSC实验结果.DSC等温退火的实验和KWW(Kohlrausch-Williams-Watts)衰变函数分析结果表明,EG无定形和50％EG中的两种无定形有不同的焓松弛行为.     

Glass-state amorphous salt solids formed by freeze-drying of amines and hydroxy carboxylic acids: effect of hydrogen-bonding and electrostatic interactions

We studied effect of molecular interactions on the physical properties of binary freeze-dried solids and frozen aqueous solutions using model chemicals containing various functional groups (amino, carboxyl, hydroxyl). Thermal analysis of frozen solutions containing alkyl diamines and hydroxy di- or tricarboxylic acids showed thermal transitions (T(g)': glass transition of maximally freeze-concentrated phase) at temperatures higher than those of the individual solutes. A binary frozen solution containing 80 mM 1,3-diamino-2-hydroxypropane (single-solute T(g)'<-60 degrees C) and 120 mM citric acid (single-solute T(g)': -55.0 degrees C) made the transition at -30.8 degrees C. The molecular weight of the solutes had smaller effects on the transition temperatures of the frozen mixture component solutions. Lyophilization of some high T(g)' mixture frozen solutions (e.g., 1,3-diamino-2-hydroxypropane and citric acid) resulted in cake-structure amorphous solids with glass transition temperatures (T(g)) higher than those of the individual components. Networking of intense hydrogen-bondings and electrostatic interactions between the heterogeneous molecules through the multiple functional groups was suggested to reduce the component mobility in the amorphous freeze-concentrated phase and the freeze-dried solids. Controlling the interactions should be a key to optimizing the physical properties of multi-component amorphous freeze-dried pharmaceutical formulations.     

Isomorphic behavior of poly(aryl ether ketone) blends

Blends of various poly(aryl ether ketones) have been found to exhibit a range of miscibility and isomorphic behavior. This range is dependent on molecular weight; however, for poly(aryl ether ketones) with number-average molecular weight of 20,000, this range is about ±25% difference in ketone content. All miscible blends exhibit isomorphism, and all immiscible blends exhibit no evidence of isomorphism. The dependence of the glass transition temperature T_g versus composition exhibits a minimum deviation from linearity whereas the melting temperature T_m versus composition exhibits a pronounced maximum deviation from linear behavior. The crystalline melting point versus composition for isomorphic blends is considerably different than for random copolymers with isomorphic units. Homopolymers and random copolymers exhibit a melting point that is a linear function of ketone content (increasing ketone content increases T_m). For blends, the melting point is essentially the same as that of the higher melting constituent until high levels of the lower melting constituent are present. The observed melting point versus composition behavior will be interpreted using classical theory to calculate the components of the liquid and crystalline phase compositions. As a miscible blend is cooled from the melt, essentially pure component of the highest melting point crystallizes out of solution, as predicted by calculated solid-liquid phase diagrams. This occurs until the crystallization is complete owing to spherulitic impingement. At high concentrations of the lower melting constituent, lower melting points will be observed because the highest melting constituent will be depleted before the crystallization is complete. In many miscible blends involving addition of an amorphous polymer to a crystalline polymer, the degree of crystallinity of the crystalline polymer has been shown to increase. On the basis of evidence presented here, it is hypothesized that dilution by a miscible, amorphous polymer allows for a higher level of crystallinity.     

新型sPS/PA6/SsPS-H塑料合金的性能和形态结构

研究新型sPS PA6 SsPS H塑料合金的力学性能和微观形态结构 .间规聚苯乙烯 (sPS)的磺化产物磺化间规聚苯乙烯 (SsPS H)的加入明显地改善了sPS PA6(聚酰胺 6)二组分合金的力学性能 ,在sPS PA6 SsPS H重量组成为 80 2 0 5时 ,三组分合金的冲击强度最大 ,为 1 5 6kJ m2 ,约为纯sPS冲击强度的 3倍 DMA和SEM结果表明 ,SsPS H对sPS和PA6共混有良好的增容作用 ,它起到了降低合金的微相尺寸和加强相间界面粘结的作用 .此外 ,FTIR结果还表明SsPS H和PA6之间存在特殊相互作用 ,其作用方式是通过SsPS H的磺酸基将其质子转移给PA6酰胺基的氮