Glass transition,crystallization, and morphology relationships in miscible poly(aryl ether ketones) and poly(ether imide) blends

The relationships among glass transition, crystallization, melting, and crystal morphology of poly(aryl ether ketone) (PAEK)/poly(other imide) (PEI) blends was studied by thermal, optical and small-angle x-ray scattering (SAXS) methods. Two types of PAEK were chosen for this work: poly(aryl ether ether ketone), PEEK, and poly(aryl ether ketone ketone), PEKK, which have distinctly different crystallization rates. Both PAEKs show complete miscibility with PEI in the amorphous phase. As PAEK crystallizes, the noncrystallizable PEI component is rejected from the crystalline region, resulting in a broad amorphous population, which was indicated by the broadening and the increase of T_g over that of the purely amorphous mixture. The presence of the PEI component significantly decreases the bulk crystallization and crystal growth rate of PAEK, but the equilibrium melting temperature and crystal surface free energies are not affected. The morphology of the PEI segregation was investigated by SAXS measurements. The results indicated that the inter(lamellar-bundle) PEI trapping morphology was dominant in the PEEK/PEI blends under rapid crystallization conditions, whereas the interspherulitic morphology was dominant in the slow crystallizing PEKK/PEI blends. These morphologies were qualitatively explained by the expression δ=D/G, where G was the crystal growth rate and D was the mutual diffusion coefficient. © 1993 John Wiley & Sons, Inc.     

Highly phenylated poly(aryl ether phthalazine)s

Two series of novel amorphous poly(aryl ether phthalazine)s have been prepared via an intramolecular ring closure reaction of poly(aryl ether ketone)s (PAEKs) with hydrazine monohydrate. Fluorinated PAEKs, which display solubility in solvents incorporating a ketone functionality such as acetone or ethyl acetate, were converted to poly(aryl ether phthalazine)s to observe if these polymers would display similar solubility characteristics. The poly(aryl ether phthalazine)s have glass transition temperatures in the range of 278–320°C and show 5% weight loss points greater than 500°C in air and nitrogen atmospheres. The fluorinated poly(aryl ether phthalazine)s were not soluble in ketonic solvents. A series of poly(aryl ether phthalazine)s incorporating pendant 2-naphthalenyl moieties has been prepared in an attempt to produce amorphous, thermally stable polymers with high glass transition temperatures. The polymers have glass transition temperatures in the range of 287–334°C and show 5% weight loss points greater than 500°C in air and nitrogen atmospheres. Poly(aryl ether phthalazine)s undergo an exothermic reaction above the glass transition temperature. The major product of this reaction is a rearrangement of the phthalazine moieties to quiazoline moieties, however some crosslinking of the polymers occurs. Cured samples of the poly(aryl ether phthalazine)s show a small increase in the polymer T_g and are insoluble in all solvents tested. © 1996 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 34:1897–1905, 1996     

Polymer-polymer miscibility in blends of a new poly(aryl ether ketone) with poly(ether imide)

Polymer miscibility was found for a blend system comprising of a new poly(aryl ether ketone) and a poly(ether imide). Phase homogeneity was preliminarily confirmed using optical and scanning electron microscopy, indicating that the scales of phase homogeneity in the blends were beyond the resolution limits of either microscopy. A composition-dependent, single glass transition temperature (T_g) in the PAEK/PEI blends within the full range of composition was observed using differential scanning calorimetry (DSC). The thermal transition breadth also suggests that the scales of mixing are fine and uniform.     

Relationship between molecular structure and thermal properties of poly(aryl ether ketone)s

Five kinds of poly(aryl ether ketone)s (PAEKs) having para-substituted linear molecular chains were synthesized via nucleophilic substitution reaction of the corresponding difluoro- and dihydroxy-compounds. The glass transition temperature and melting temperature of the PAEKs measured through differential scanning calorimetry in addition to those of other PAEKs reported are approximately proportional to the logarithm of the ratio of the mole fractions of ketone and ether groups in the repeating unit of the PEAKs. On the other hand, this ratio does not affect the crystal structure of the PAEKs.     

Rhythmic growth of ring‐banded spherulites in blends of liquid crystalline methoxy‐poly(aryl ether ketone) and poly(aryl ether ether ketone)

Rhythmic growth of ring‐banded spherulites in blends of liquid crystalline methoxy‐poly(aryl ether ketone) (M‐PAEK) and poly(aryl ether ether ketone) (PEEK) has been investigated by means of differential scanning calorimetry (DSC), polarized light microscopy (PLM), and scanning electron microscopy (SEM) techniques. The measurements reveal that the formation of the rhythmically grown ring‐banded spherulites in the M‐PAEK/PEEK blends is strongly dependent on the blend composition. In the M‐PAEK‐rich blends, upon cooling, an unusual ring‐banded spherulite is formed, which is ascribed to structural discontinuity caused by a rhythmic radial growth. For the 50:50 M‐PAEK/PEEK blend, ring‐banded spherulites and individual PEEK spherulites coexist in the system. In the blends with PEEK as the predominant component, M‐PAEK is rejected into the boundary of PEEK spherulites. The cooling rate and crystallization temperature have great effect on the phase behavior, especially the ring‐banded spherulite formation in the blends. In addition, the effects of M‐PAEK phase transition rate and phase separation rate on banded spherulite formation is discussed. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 3011–3024, 2007     

Thermal,mechanical and dielectric behaviour of poly(aryl ether ketone) with low melting temperature

New poly(aryl ether ketone)s (PAEKs) with a low melting temperature (relative to PEEK) are of interest in order to simplify the manufacturing of high-performance polymers or composites. In this study, we propose to investigate the physical properties of a new PAEK from Victrex, namely PAEK LM. Combinations of thermal analyses were used as follows: standard and modulated temperature differential scanning calorimetry, dynamic mechanical analysis, dynamic dielectric analysis and guarded hot plate technique. We found that the global mechanical, dielectric and thermal properties are very similar to the PEEK reference. The glass transition temperature was observed in the same range than PEEK (∼ 150 °C) while the melting temperature T_m was measured at 307 °C for PAEK LM which is about 35 °C below the melting temperature of PEEK. The degree of crystallinity of PAEK LM was found to be 27% while for PEEK it is 38%, depending on the processing conditions. This work explored crystalline structure–property relationships to explain the behaviour of PAEK LM.

     

Novel poly(aryl ether phthalazinium) ionomers and their properties

The synthesis of N-phenyl phthalazinium salts by condensation of a 1,2-diaroylbenzene with phenylhydrazine is described. This reaction was utilized to prepare novel poly(aryl ether phthalazinium) ionomers by the direct condensation of poly(aryl ether ketone)s with phenylhydrazine. The preparation of poly(aryl ether phthalazinium) ionomers by methylation of poly(aryl ether phthalazine)s is also described. Most of the ionomers are amorphous, thermally stable, and soluble in organic solvents. They can be cast into flexible and strong films. The glass transition temperature of the ionomers ranges from 297 to 363°C, an increase of 12 to 100°C over the corresponding neutral polymers. © 1996 John Wiley & Sons, Inc.     

Effects of miscible diluent of poly(ether imide) on ring-banded morphology of poly(trimethylene terephthalate)

The melting, crystallization, and self-packed ring patterns in the spherulites of miscible blends comprising poly(trimethylene terephthalate) (PTT) and poly(ether imide) (PEI) were revealed by optical, scanning electron microscopies (PLM and SEM) and differential scanning calorimetry (DSC). Morphology and melting behavior of the miscible PTT/PEI blends were compared with the neat PTT. Ringed spherulites appeared in the miscible PTT/PEI blends at all crystallization temperatures up to 220 °C, whereas at this high temperature no rings were seen in the neat PTT. A postulation was proposed, and interrelations between rings in spherulites and the multiple lamellae distributions were investigated. The specific interactions and the segregation of amorphous PEI were discussed for interpreting the morphological changes of 220 °C-melt-crystallized PTT/PEI samples. Interlamellar segregation of PEI might be associated with multiple lamellae in the spherulites of PTT/PEI blends; therefore, rings were more easily formed in the PTT/PEI blends at all crystallization temperatures. A postulated model of uneven lamellar growth, coupled with periodical spiraling, more properly describes the possible origin of ring bands from combined effects of both interactions and segregation between the amorphous PEI and PTT in blends.     

Novel fluorinated poly(aryl ether ketone)s

Two novel fluorinated monomers were prepared and polymerized with biphenols to produce amorphous, thermally stable poly(aryl ether ketone)s. The properties of the fluorinated polymers are compared to those of unfluorinated, amorphous poly(aryl ether ketone)s. The presence of fluorine in the polymers was found to cause a decrease in glass transition temperature and Young's moduli, however, no increase in thermal stability was observed. The fluorinated polymers are soluble in common organic solvents such as chloroform and methylene chloride at room temperature, and also show solubility in solvents containing a ketonic moiety, such as acetone. Evidence of polymer branching through fluorines considered to be unreactive under the polymerization conditions was found. Efforts were made to evaluate the reactivity of fluorine atoms under the polymerization conditions using both molecular modeling and ¹⁹F-NMR to ascertain if such branching could be avoided. © 1995 John Wiley & Sons, Inc.     

Relationship between morphology and glass transition temperature in solvent-crystallized poly(aryl ether ketones)

The relationship between semicrystalline morphology and glass transition temperature has been investigated for solvent-crystallized poly(ether ether ketone) (PEEK) and poly(ether ketone ketone) (PEKK). Solvent-crystallized specimens of both PEEK and PEKK displayed a sizeable positive offset in T_g compared to quenched amorphous specimens as well as thermally crystallized specimens of comparable bulk crystallinity; the offset in T_g for the crystallized samples reflected the degree of constraint imposed on the amorphous segments by the crystallites. Small-angle X-ray scattering studies revealed markedly smaller crystal long periods (d) for the solvent-crystallized specimens compared to samples prepared by direct cold crystallization. The strong inverse correlation observed between T_g and interlamellar amorphous thickness (l_A) based on a simple two-phase model was in excellent agreement with data reported previously for PEEK, and indicated the existence of a unique relationship between glass transition temperature and morphology in these poly(aryl ether ketones) over a wider range of sample preparation history and lamellar structure than was previously reported. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36 : 65–73, 1998     

PPEKK/PEI共混物的相容性及拉伸性能

作为相容体系 ,聚芳醚酮与聚醚酰亚胺 (ＰＥＩ)共混物体系的研究受到了研究者的重视[1～ 4] .由于现在已商品化的聚芳醚酮基本上都是半结晶型聚合物 ,所以有有关无定型聚芳醚酮与聚醚酰亚胺共混物的研究鲜见报道 .含二氮杂萘酮结构聚芳醚酮酮 (ＰＰＥＫＫ)是一种新型耐高温聚合物 ,相比于已经商品化的各种聚芳醚酮 ,ＰＰＥＫＫ除具有优异的综合性能外 ,它最大的特点表现在以下两方面 ,ＰＰＥＫＫ耐热性突出 ,玻璃化转变温度 (Ｔｇ)为 2 4 5℃左右 ,远高于各种商品化的聚芳醚酮 ;ＰＰＥＫＫ为无定型聚合物 ,易溶于多种有机极性溶剂 ,大大的扩…     

聚芳醚酮树脂的分子设计与合成及性能

聚芳醚酮树脂是20世纪发展起来的重要特种工程塑料.因其优良的耐热、耐腐蚀、耐摩擦及生物相容性好等特点,在国防军工、武器装备、航空航天、电子、汽车、机械、石油工业、核能及理疗卫生等高技术领有广泛的应用.此类材料大都采用双酚单体和双氟单体通过A2+B2型亲核缩聚反应制备.这类聚合物的分子结构对材料的性能影响较大,一般情况下分子链由醚、酮、苯三元规整结构构成时,聚合物为半结晶态;然而,当分子结构中存在侧基或其他非规整结构往往破坏聚合物的结晶结构,聚合物呈现无定型态.半结晶聚芳醚酮聚合物具有非常优异的耐热、耐化学稳定性一般作为结构型材料使用;无定型聚芳醚酮具有良好的加工性能,并且可进行一些功能化成为一类优异的功能型材料.本文从结构与性能关系出发,介绍了聚芳醚酮树脂种类,聚芳醚酮树脂的发展历程及合成方法;探讨了聚芳醚酮材料结构与性能关系;总结了功能性聚芳醚酮材料的前沿进展;最后结合实际展望了聚芳醚酮的应用发展方向.     

Vitrification/devitrification phenomena during isothermal and nonisothermal crystallization of poly(aryl–ether–ether–ketone) (PEEK) and PEEK/poly(ether–imide) blends

We have established time–temperature transformation and continuous-heating transformation diagrams for poly(ether–ether–ketone) (PEEK) and PEEK/poly(ether–imide) (PEI) blends, in order to analyze the effects of relaxation control on crystallization. Similar diagrams are widely used in the field of thermosetting resins. Upon crystallization, the glass transition temperature (T_g) of PEEK and PEEK/PEI blends is found to increase significantly. In the case of PEEK, the shift of the α-relaxation is due to the progressive constraining of amorphous regions by nearby crystals. This phenomenon results in the isothermal vitrification of PEEK during its latest crystallization stages for crystallization temperatures near the initial T_g of PEEK. However, vitrification/devitrification effects are found to be of minor importance for anisothermal crystallization, above 0.1°C/min heating rate. In the case of PEEK/PEI blends, amorphous regions are progressively enriched in PEI upon PEEK crystallization. This promotes a shift of the α-relaxation of these regions to higher temperatures, with a consequent vitrification of the material when crystallized below the T_g of PEI. The data obtained for the blends in anisothermal regimes allow one to detect a region in the (temperature/heating rate) plane where crystallization proceeds in the continuously close proximity of the glass transition (dynamic vitrification). These experimental findings are in agreement with simple simulations based on a modified Avrami model coupled with the Fox equation. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 919–930, 1998     

Fully aromatic poly(ether ketone)s bearing macrocycle pendants: Synthesis and crosslinking

This study reports a method to prepare fully aromatic poly(ether ketone) thermosets. The cyclization of 2′,5′‐dimethoxy[1,1′‐biphenyl]‐2,5‐diol and a difluoro monomer was carried out under pseudo high dilution condition. Two types of fully aromatic poly(ether ketone)s with macrocycle were successfully prepared by copolymerization of macrocycle of aryl ether ketone containing hydroxyphenyl groups, 4,4′‐(hexafluoroisopropylidene)diphenol (HFBPA), and 4,4‐difluorobenzophenone. The obtained copolymers have high molecular mass, good solubility, and high glass transition temperatures in the presence of CsF, the crosslinking reaction of copolymers occurred and afforded fully aromatic thermoset poly(aryl ether ketone)s by ring‐opening reaction driven by entropy. After crosslinking, these copolymers show much higher glass transition temperatures, excellent thermal stability, and better mechanical strength. © Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 7002–7010, 2008     

A Fourier transform Raman spectroscopy study of the crystallization behaviour of poly (ether ether ketone)/poly (ether imide) blends

This paper describes a study of the crystallization behaviour of blends consisting of the polymers poly (ether ether ketone) (PEEK) and poly (ether imide) (PEI) using Fourier transform Raman spectroscopy. The annealing process of PEEK was followed for the virgin polymer and also when it was blended with PEI. The data presented show that the crystallization process of PEEK is inhibited by the presence of the PEI, but the extent of the crystallinity is increased. There is also evidence that the presence of the PEI induces premelting of the PEEK.     

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.     

Isothermal melt and cold crystallization kinetics of poly(aryl ether ketone ether ketone ketone)

The isothermal melt and cold crystallization kinetics of poly(aryl ether ketone ether ketone ketone) are investigated by differential scanning calorimetry over two temperature regions. The Avrami equation describes the primary stage of isothermal crystallization kinetics with the exponent n ≈ 2 for both melt and cold crystallization. With the Hoffman–Weeks method, the equilibrium melting point is estimated to be 406 °C. From the spherulitic growth equation proposed by Hoffman and Lauritzen, the nucleation parameter (K_g) of the isothermal melt and cold crystallization is estimated. In addition, the K_g value of the isothermal melt crystallization is compared to those of the other poly(aryl ether ketone)s. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 1992–1997, 2000     

Mechano-optical behavior in poly (ethylene terephthalate)/poly (ether imide) blends

Mechano-optical behavior and related structural evolution during uniaxial stretching of melt miscible poly (ethylene terephthalate) (PET)/poly (ether imide) (PEI) blends were studied near their glass transition temperature using an instrumented machine that measures true stress, true strain and spectral birefringence simultaneously. Stretching from amorphous state, two distinct stress-optical regimes were observed at temperatures between T_g and T_cc (cold crystallization). Near T_g, a typical photoelastic behavior persists until a critical temperature above which temperature independent initial stress optical behavior is observed. At those temperatures above T_g, where glassy behavior is observed, decreasing stretching rate was also found to eliminate this glassy photo elastic regime leading to the observation of a linear initial stress optical behavior that becomes temperature independent as expected from linear stress optical rule. Increasing PEI concentration in the blends suppresses crystallizability and increases temperature at which initial elastic region disappears giving way to pure liquid behavior where linear stress optical behavior is observed. This is attributed to the increase and broadening of the glass transition temperature with the addition of noncrystallizable PEI. In PET/PEI blends, the stress-optical coefficient (SOC), determined in a linear stress optical regime, was found to increase linearly with the increase in PEI concentration.     

Preparation and properties of novel soluble poly(aryl ether)s bearing covalently bound tetrapyrazinoporphyrazine units

Thermooxidatively stable amorphous poly(dicyanopyrazine ether)s with high glass transition temperatures are synthesized and converted into poly(aryl ether)s bearing covalently bound zinc(II) 2,3,9,10,16,17,23,24-octaphenyltetrapyrazinoporphyrazine units. They are soluble in common organic solvents and can be cast into strong and flexible films. The maximum absorption wavelength of the poly(aryl ether)s bearing zinc (II) 2,3,9,10,16,17,23,24-octaphenyltetrapyrazinoporphyrazine units in chloroform is 654 nm. © 1995 John Wiley & Sons, Inc.     

Synthesis and optical properties of poly(aryl ether ketone)s incorporating porphyrins in the backbones

A series of novel soluble poly(aryl ether ketone)s (PAEKs) based on 5,10‐bis(4‐hydroxyphenyl)?15,20‐diphenylporphyrin (cis‐DHTPP), 4,4′‐(hexafluoroisopropylidene) diphenol (6FBPA) and 4,4′‐difluorobenzophenone (DFB) were synthesized and characterized by FT‐IR, ¹H‐NMR, UV–vis and fluorescence spectroscopies. The intrinsic photophysical properties of porphyrins were preserved because of the absence of photoinduced electron transfer in the polymer chains. Investigation of the copolymers thermal properties indicated that these polymers had high glass transition temperatures and excellent thermal stabilities. The results of Z‐scan and optical limiting measurements manifested that incorporation of the porphyrin chromophore into the main chain engendered the novel PAEKs with superior nonlinear optical properties and optical limiting function, which could be effectively tuned by varying the molar ratio of porphyrin monomers. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 1282–1290