Properties and crystallization kinetics of poly(ether ether ketone)‐co‐poly(ether ether ketone ketone) block copolymers

A series of block copolymers composed of poly(ether ether ketone) (PEEK) and poly(ether ether ketone ketone) (PEEKK) components were prepared from their corresponding oligomers via a nucleophlilic aromatic substitution reaction. Various properties of the copolymers were investigated with differential scanning calorimetry (DSC) and a tensile testing machine. The results show that the copolymers exhibited no phase separation and that the relationship between the glass‐transition temperature (T_g) and the compositions of the copolymers approximately followed the formula T_g = T_g1X₁ + T_g2X₂, where T_g1 and T_g2 are the glass‐transition‐temperature values of PEEK and PEEKK, respectively, and X₁ and X₂ are the corresponding molar fractions of the PEEK and PEEKK segments in the copolymers, respectively. These copolymers showed good tensile properties. The crystallization kinetics of the copolymers were studied. The Avrami equation was used to describe the isothermal crystallization process. The nonisothermal crystallization was described by modified Avrami analysis by Jeziorny and by a combination of the Avrami and Ozawa equations. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 1652–1658, 2005     

Structure,crystallization, and properties of poly(aryl ether ether ketone ketone)s containing meta-phenyl links and their copolymers

Poly(aryl ether ether ketone ketone)s (PEEKK) containing meta-phenyl links and their series of copolymers were synthesized and investigated by both X-ray and differential scanning calorimetry (DSC) methods. Results showed that the heat properties of this kind of copolymer depended greatly on the content of meta-phenyl links in the copolymer system, in which occurred the lowest melting point. Results from X-rays showed that PEEKK containing meta-phenyl links had no (111) crystal face diffraction. These proved that meta-phenyl links had introduced asymmetrical factors, which had produced poor crystal structure and difficulty in crystallization. Even so, the modification of PEEKK by introducing the meta-phenyl links improved the polymer composite performances, e.g., the copolymer M₂, which kept performances close to PEEKK but better than PEEK. DSC results of M₂ showed that its Avrami number (n) was 1.5 and its crystal grew fibrously from isothermal crystallization of the melting state, while for the nonisothermal crystallization from the melting state, n was 4.4 to the spherical crystal growth, and the activation energy (ΔE) of crystallization was 184 kJ/mol, which was less than the ΔE of 296 kJ/mol for PEEKK crystallized from the nonisothermal melting state. When M₂ was isothermally crystallized from the rubber state, its n was 2 to the disklike crystal growth, while its n was 4.6 to the spherulitic crystal growth for the nonisothermal crystallization state of melting. The isothermal crystallization process was different from the nonisothermal process in the crystal nucleation and growth for M₂. © 1996 John Wiley & Sons, Inc.     

Synthesis and properties of copolymers of poly(ether ketone ketone) and poly(ether amide ether amide ether ketone ketone)

Poly(aryl ether ketone)s (PAEKs) are a class of high‐performance engineering thermoplastics known for their excellent combination of chemical, physical and mechanical properties, and the synthesis of semicrystalline PAEKs with increased glass transition temperatures (T_g) is of much interest. In the work reported, a series of novel copolymers of poly(ether ketone ketone) (PEKK) and poly(ether amide ether amide ether ketone ketone) were synthesized by electrophilic solution polycondensation of terephthaloyl chloride with a mixture of diphenyl ether and N,N′‐bis(4‐phenoxybenzoyl)‐4,4′‐diaminodiphenyl ether (BPBDAE) under mild conditions. The copolymers obtained were characterized using various physicochemical techniques. The copolymers with 10–35 mol% BPBDAE are semicrystalline and have markedly increased T_g over commercially available poly(ether ether ketone) and PEKK due to the incorporation of amide linkages in the main chain. The copolymers with 30–35 mol% BPBDAE not only have high T_g of 178–186 °C, but also moderate melting temperatures of 335–339 °C, having good potential for melt processing. The copolymers with 30–35 mol% BPBDAE have tensile strengths of 102.4–103.8 MPa, Young's moduli of 2.33–2.45 GPa and elongations at break of 11.7–13.2%, and exhibit high thermal stability and good resistance to organic solvents. Copyright © 2010 Society of Chemical Industry     

Crystallization behavior of poly(ether ether ketone ketone)

The melting behavior of semicrystalline poly(ether ether ketone ketone) (PEEKK) has been studied by differential scanning calorimetry (DSC). When PEEKK is annealed from the amorphous state, it usually shows two melting peaks. The upper melting peaks arise first, and the lower melting peaks are developed later. The upper melting peaks shown in the DSC thermogram are the combination (addition) of three parts: initial crystal formed before scanning; reorganization; and melting-recrystallization of lower melting peaks in the DSC scanning period. In the study of isothermal crystallization kinetics, the Avrami equation was used to analyze the primary process of the isothermal crystallization; the Avrami constant, n, is about 2 for PEEKK from the melt and 1.5 for PEEKK from the glass state. According to the Lauritzen-Hoffman equation, the kinetic parameter of PEEKK from the melt is 851.5 K; the crystallization kinetic parameter of PEEKK is higher than that of PEEK, and suggests the crystallizability of PEEKK is less than that of PEEK. The study of crystallization on PEEKK under nonisothermal conditions is also reported for cooling rates from 2.5°C/min to 40°C/min, and the nonisothermal condition was studied by Mandelkern analysis. The results show the nonisothermal crystallization is different from the isothermal crystallization. © 1996 John Wiley & Sons, Inc.     

The absorption behavior and crystallization of poly(aryl ether ketone) films

The absorption and subsequent desorption behaviors of amorphous polymer films of PEEK poly(ether ether ketone), PEEKK poly(ether ether ketone ketone), and PEKK poly(ether ketone ketone) in solvent of 1,2-dichloroethane (C₂H₄Cl₂) are investigated and compared. The equilibrium absorption weight (M_∞) of these polymers is related to their molecular ketone content or molecular chain rigidity and also to the experimental conditions. Especially, at a certain temperature, the molecular chains in the solvent can be polarized, which leads to producing greater M_∞ for polymer films; for example, at 60°C, M_∞ = 46% for PEEK and M_∞ = 65% for PEKK. The pseudodiffusion coefficients for PEEK, PEEKK, and PEKK all surpass the 6.0 × 10⁻¹² m² s⁻¹. The polymer's molecular polarization has been proved in concentrated sulfur acid. Results also show that amorphous resin's films become white and creeped in dichloroethane, which is more serious when metaphenyl links are introduced into PEEKK or PEKK molecular main chains. The residual solvent of 1% or so often exists in the films, even though a long desorption time (over 100 h) has been proceeded. Absorption has induced crystallization of amorphous polymer films, but this crystallization process is slightly different from that of the films crystallized from both the glassy state and the melting state in the solvent, which makes the amorphous interlayers grow progressively and more condensely; thus, the crystallized films will have higher T_g's than these crystallized under annealing condition. The morphology results have shown that the solvent-crystallized films are less toughened than the amorphous ones because of the intermediate layer between the induced crystallized area and the amorphous area in the core. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 67:2065–2075, 1998     

Synthesis and properties of novel copolymers of poly(ether ketone diphenyl ketone ether ketone ketone) and poly(ether amide ether amide ether ketone ketone)

New monomers, 4,4′‐bis(4‐phenoxybenzoyl)diphenyl (BPOBDP) and N,N′‐bis(4‐phenoxybenzoyl)?4,4′‐diaminodiphenyl ether (BPBDAE), were conveniently synthesized via simple synthetic procedures from readily available materials. Novel copolymers of poly(ether ketone diphenyl ketone ether ketone ketone) (PEKDKEKK) and poly(ether amide ether amide ether ketone ketone) (PEAEAEKK) were synthesized by electrophilic Friedel‐Crafts solution copolycondensation of isophthaloyl chloride (IPC) with a mixture of BPOBDP and BPBDAE, over a wide range of BPOBDP/BPBDAE molar ratios, in the presence of anhydrous AlCl₃ and N‐methylpyrrolidone (NMP) in 1,2‐dichloroethane (DCE). The copolymers obtained were characterized by different physico‐chemical techniques. The copolymers with 10–40 mol% BPBDAE are semicrystalline and had remarkably increased T_gs over commercially available PEEK and PEKK due to the incorporation of amide and diphenyl linkages in the main chains. The copolymers IV and V with 30–40 mol% BPBDAE had not only high T_gs of 185–188°C, but also moderate T_ms of 326–330°C, having good potential for the melt processing. The copolymers IV and V had tensile strengths of 101.7–102.3 MPa, Young's moduli of 2.19–2.42 GPa, and elongations at break of 13.2–16.6% and exhibited high thermal stability and excellent resistance to organic solvents. POLYM. ENG. SCI., 54:1757–1764, 2014. © 2013 Society of Plastics Engineers     

Synthesis and properties of novel copolymers of poly(ether ketone ether ketone ketone) and poly(ether ketone ketone ether ketone ketone) containing 1,4‐naphthylene moieties

A new monomer, 1,4‐bis(4‐phenoxybenzoyl)naphthalene (BPOBN), was conveniently synthesized via a simple synthetic procedure from readily available materials. A series of novel copolymers of poly(ether ketone ether ketone ketone) and poly(ether ketone ketone ether ketone ketone) containing 1,4‐naphthylene moieties were prepared by the Friedel‐Crafts acylation solution copolycondensation of terephthaloyl chloride (TPC) with a mixture of BPOBN and 4,4′‐diphenoxybenzophenone (DPOBPN), over a wide range of BPOBN/DPOBPN molar ratios, in the presence of anhydrous AlCl₃ and N‐methylpyrrolidone in 1,2‐dichloroethane. The copolymers with 10–40% BPOBN are semicrystalline and had remarkably increased T_gs over the conventional PEEK and PEKK due to the incorporation of 1,4‐naphthylene moieties in the main chains. The copolymers with 30–40 mol% BPOBN had not only high T_gs of 176–177°C, but also moderate T_ms of 332–338°C, which are suitable for the melt processing. These polymers had tensile strengths of 101.5–104.7 MPa, Young's moduli of 2.49–2.65 GPa, and elongations at break of 13.3–15.7% and exhibited high thermal stability and excellent resistance to organic solvents. POLYM. ENG. SCI., 56:566–572, 2016. © 2016 Society of Plastics Engineers     

Synthesis and characterization of poly(ether amide ether ketone)/poly(ether ketone ketone) copolymers

A new monomer, N,N′‐bis(4‐phenoxybenzoyl)‐m‐phenylenediamine (BPPD), was prepared by condensation of m‐phenylenediamine with 4‐phenoxybenzoyl chloride in N,N‐dimethylacetamide (DMAc). A series of novel poly(ether amide ether ketone) (PEAEK)/poly(ether ketone ketone) (PEKK) copolymers were synthesized by the electrophilic Friedel‐Crafts solution copolycondensation of terephthaloyl chloride (TPC) with a mixture of diphenyl ether (DPE) and BPPD, over a wide range of DPE/BPPD molar ratios, in the presence of anhydrous AlCl₃ and N‐methylpyrrolidone (NMP) in 1,2‐dichloroethane (DCE). The influence of reaction conditions on the preparation of copolymers was examined. The copolymers obtained were characterized by different physicochemical techniques. The copolymers with 10–25 mol % BPPD were semicrystalline and had remarkably increased T_gs over commercially available PEEK and PEKK due to the incorporation of amide linkages in the main chains. The copolymers III and IV with 20–25 mol % BPPD had not only high T_gs of 184–188°C, but also moderate T_ms of 323–344°C, having good potential for the melt processing. The copolymers III and IV had tensile strengths of 103.7–105.3 MPa, Young's moduli of 3.04–3.11 GPa, and elongations at break of 8–9% and exhibited outstanding thermal stability and good resistance to organic solvents. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Synthesis and characterization of poly(ether ketone ether ketone ketone)/poly(ether ether ketone ketone) copolymers containing naphthalene and pendant cyano groups

2,6‐Bis(β‐naphthoxy)benzonitrile (BNOBN) was synthesized by reaction of β‐naphthol with 2,6‐difluorobenzonitrile in N‐methyl‐2‐pyrrolidone (NMP) in the presence of KOH and K₂CO₃. Poly(ether ketone ether ketone ketone)(PEKEKK) /poly(ether ether ketone ketone) (PEEKK) copolymers containing naphthalene and pendant cyano groups were obtained by electrophilic Friedel‐Crafts polycondensation of terephthaloyl chloride (TPC) with varying mole proportions of 4,4′‐diphenoxybenzophenone (DPOBP) and 2,6‐bis(β‐naphthoxy)benzonitrile (BNOBN) using 1,2‐dichloroethane (DCE) as solvent and NMP as Lewis base in the presence of anhydrous AlCl₃. The resulting polymers were characterized by various analytical techniques, such as FTIR, DSC, TG, and WAXD. The results indicated that the crystallinity and melting temperature of the polymers decreased with increase in concentration of the BNOBN units in the polymer, the glass transition temperature of the polymers increased with increase in concentration of the BNOBN units in the polymer. Thermogravimetric studies showed that all the polymers were stable up to 536°C in N₂ atmosphere. The copolymers have good resistance to acidity, alkali, and organic solvents. Because of the melting temperature (T_m) depression with increase in the BNOBN content in the reaction system, the processability of the resultant coplymers could be effectively improved. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Miscibility and phase behavior in blends containing random copolymers of poly(ether ether ketone) and phenolphthalein poly(ether ether ketone)

The miscibility and phase behavior of polysulfone (PSF) and poly(hydroxyether of bisphenol A) (phenoxy) with a series of copoly (ether ether ketone) (COPEEK), a random copolymer of poly(ether ether ketone) (PEEK), and phenolphthalein poly(ether ether ketone) (PEK-C) was studied using differential scanning calorimetry. A COPEEK copolymer containing 6 mol % ether ether ketone (EEK) repeat units is miscible with PSF, whereas copolymers containing 12mol % EEK and more are not. COPEEK copolymers containing 6 and 12 mol % EEK are completely miscible with phenoxy, but those containing 24 mol % EEK is partially miscible with phenoxy. Moreover, a copolymer containing 17 mol % EEK is partially miscible with phenoxy; the blends show two transitions in the midcomposition region and single transitions at either extreme. Two T_gs were observed for the 50/50 blend of phenoxy with the coplymer containing 17 mol % EEK, whereas a single composition-dependent T_g appeared for all the other compositions. An FTIR study revealed that there exist hydrogen-bonding interactions between phenoxy and the copolymers. The strengths of the hydrogen-bonding interactions in the blends of the COPEEK copolymers containing 6 and 12 mol % EEK are the same as that in the phenoxy/PEK-C blend. However, for the blends of copolymers containing 17, 24, and 28 mol % EEK, the hydrogen-bonding interactions become increasingly unfavorable and the self-association of the hydroxyl groups of phenoxy is preferable as the content of EEK units in the copolymer increases. The observed miscibility was interpreted qualitatively in terms of the mean-field approach. © 1996 John Wiley & Sons, Inc.     

Investigations of the practical routes,structure, and properties for poly(aryl ether ketone ketone) polymers

Different routes for preparing poly(aryl ether ketone)s (PEKKs) are presented and compared. The properties of PEKKs are related to the content of metaphenyl links in the molecular main chains, the molecular chain branching degree, the gelation content by molecular crosslinks, and, especially, the relative content of crystal form II to crystal form I of the PEKK polymorphism. When the molecular T/I ratio of 50/50 in the polymer chains is reached, the obtained PEKK has a lower melting point and gelation content (2% or so). The PEKKs prepared from the electronical substitution route (E route) often have a 0–30% content of crystal form II (relative to the mixed form I and form II), which is much more than that in PEKKs from the nucleophilic substitution route (N route, form II accounts for 0–20%). The relatively unstable crystal form II resulted in the unstable and difficultly predicted thermal properties of PEKKs. PEKKs from different routes provide samples with melting points from 360 to 397°C (T_m) and glassy transition temperatures (T_g) from 167 to 176°C and the equilibrium melting point of 411°C for para-PEKK, while the tensile strength of the homopolymer PEKK and copolymers of PEEKK (poly(aryl ether ether ketone ketone)–PEKK can reach 100 MPa prepared by the N route. The high T_g makes PEKK polymers practically useful while too high T_m and a very small difference between T_m and T_d (degradation temperature) produce obstacles to its wide application. The reaction mechanisms of both electrophilic and nucleophilic routes are investigated and discussed in detail. Results show that the molecular chain branched by solvents and monomers with many activated points may be partly reduced to some extent by the oligomer and extruding route. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 67: 659–677, 1998     

Synthesis and characterization of poly(ether ketone ketone) (PEKK)/sodium sulfonated poly(arylene ether ketone) (S‐PAEK) block copolymers

A series of well‐defined poly(ether ketone ketone) (PEKK)/sodium sulfonated poly(aryl ether ketone) (S‐PAEK) block copolymers of high molecular weights was prepared by direct nucleophilic polymerization of hydroquinone with sodium 5,5′‐carbonylbis(2‐fluorobenzene sulfonate) ( 1 ) and PEKK oligomer ( 2 ). Varying the ratio of 1 to 2 used in polymerization can be used to control the degree of polymer sulfonation, which correspondingly affects the polymer solubility in solvents. Increasing content of 1 in the copolymers, slightly decreases their thermal stability which is nevertheless thermally stable up to 400 °C. Two T_g values, or one broad T_g, were observed in the DSC measurements of the block copolymers, indicating the existence of phase separation, which was further proved by phase‐separated morphologies as shown in atomic force microscopy images. © 2001 Society of Chemical Industry     

Miscibility and crystallization behavior of poly(ether ether ketone ketone)/poly(ether imide) blends

The miscibility and crystallization behavior of poly(ether ether ketone ketone) (PEEKK)/poly(ether imide) (PEI) blends prepared by melt‐mixing were investigated by differential scanning calorimetry. The blends showed a single glass transition temperature, which increased with increasing PEI content, indicating that PEEKK and PEI are completely miscible in the amorphous phase over the studied composition range (weight ratio: 90/10–60/40). The cold crystallization of PEEKK blended with PEI was retarded by the presence of PEI, as is apparent from the increase of the cold crystallization temperature and decrease of the normalized crystallinity for the samples anealed at 300°C with increasing PEI content. Although the depression of the apparent melting temperature of PEEKK blended with PEI was observed, there was no evidence of depression in the equilibrium melting temperature. The analysis of the isothermal crystallization at 313–321°C from the melt of PEEKK/PEI (100/0, 90/10, and 80/20) blends suggested that the retardation of crystallization of PEEKK is caused by the increase of the crystal surface free energy in addition to the decrease of the mobility by blending PEI with a high glass transition temperature. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 769–775, 2001     

Crystallization kinetics of novel poly(aryl ether ketone) copolymers containing 2,7‐naphthalene moieties

To increase the glass transition temperature (T_g) of poly(aryl ether ketone), and to decrease the melting temperature (T_m) and temperature of processing, a series of novel poly(aryl ether ketone)s with different contents of 2,7‐naphthalene moieties (PANEK) was synthesized. We focused on the influence of the naphthalene contents to the copolymer's crystallization. The crystallization kinetics of the copolymers was studied isothermally and nonisothermally by differential scanning calorimetry. In the study of isothermal crystallization kinetics, the Avrami equation was used to analyze the primary process of the crystallization. The study results of the crystallization of PANEK at cooling/heating rates ranging from 5 to 60°C/min under nonisothermal conditions are also reported. Both the Avrami equation and the modified Avrami–Ozawa equation were used to describe the nonisothermal crystallization kinetics of PANEK. The results show that the increase in the crystallization temperature and the content of 2,7‐naphthalene moieties will make the crystallization rate decrease, while the nucleation mechanism and the crystal growth of PANEK are not influenced by the increasing of the content of 2,7‐naphthalene moieties. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 2527–2536, 2006     

Segmental dynamics of functional graphene‐filled poly(ether sulfone ether ketone ketone) nanocomposites

The segmental dynamics of functional graphene (fGR)/poly(ether sulfone ether ketone ketone) (PESEKK) nanocomposites were investigated via differential scanning calorimetry and dynamic mechanical analysis (DMA) measurements. First, fGR was prepared using graphene oxide and sodium dodecylbenzene sulfonate. Subsequently, a series of fGR/PESEKK nanocomposites were prepared through solution blend. When the sulfone groups were introduced into the segments of PESEKK polymers, the glass transition temperature (T_g) of PESEKK was higher than that of free sulfone functionalized poly(ether ketone ketone). The fGR/PESEKK nanocomposites displayed a uniform nanostructure because of the strong interfacial interaction between fGR and PESEKK. With the increase in the fGR contents, the T_g values of fGR/PESEKK nanocomposites decreased. Two loss factor peaks were noted in the fGR/PESEKK nanocomposites, which were characterized via DMA. The α′‐relaxation of the nanocomposites at low temperature was assigned to polymer chains close to the polymer/filler interface with mobility higher than that in the bulk unfilled PESEKK (α‐relaxation). © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44391.     

Syntheses and characterization of poly(phenylene sulfide)–poly(ether sulfone) block copolymers

Poly(phenylene sulfide)-poly(ether sulfone) (PPS–PES) block copolymers were synthesized by polycondensation of chloro-terminated PPS oligomers and hydroxylic-terminated PES oligomers at atmospheric pressure. The structure and compositions of PPS–PES block copolymers were analyzed quantitatively by FTIR spectroscopy. It was found that the contents of PES in copolymers increase with the amount of PES in the added materials; however, the quantities of PES contents in copolymers are lower than its quantities in the added materials. The solubility, crystallization behavior, and thermal properties of PPS-PES block copolymers were studied through a solubility test, X-ray diffraction, DSC, and TGA. It was primarily proved that the copolymers have better solubility, lower crystallinity, and higher glass transition (T_g) than those of PPS. The nonisothermal crystallization kinetics and thermal decomposition kinetics of block copolymers were also studied; furthermore, the crystallization kinetic parameters and the activation energy of thermal decomposition were calculated. © 1996 John Wiley & Sons, Inc.     

Synthesis and characterization of novel copolymers of poly(ether ketone ketone) and poly(ether ketone sulfone imide)

A new monomer containing sulfone and imide linkages, bis{4-[4-(p-phenoxyphenylsulfonylphenoxy)benzoyl]-1,2-benzenedioyl}-N,N,N′,N′-4,4′-diaminodiphenyl ether (BPSPBDADPE), was prepared by the Friedel–Crafts reaction of bis(4-chloroformyl-1,2-benzenedioyl)-N,N,N′,N′-4,4′-diaminodiphenyl ether with 4,4′-diphenoxydiphenyl sulfone. Novel copolymers of poly(ether ketone ketone) and poly(ether ketone sulfone imide) were synthesized by electrophilic Friedel–Crafts solution copolycondensation of terephthaloyl chloride with a mixture of DPE and BPSPBDADPE. The polymers were characterized by different physico-chemical techniques. The polymers with 10–25?mol% BPSPBDADPE are semicrystalline and had increased T _gs over commercially available PEEK and PEKK (70/30) due to the incorporation of sulfone and imide linkages in the main chains. The polymer IV with 25?mol% BPSPBDADPE had not only high T _g of 194?°C but also moderate T _m of 338?°C, having good potential for melt processing and exhibited high thermal stability and good resistance to common organic solvents.     

Viscoelastic properties of phenolphthalein poly(ether ketone)

Stress relaxation and dynamic mechanical behavior of phenolphthalein poly(ether ketone) (PEK-C) have been investigated. Using Ferry's reduction method, the master curve was obtained. From the experimental results, we found that the WLF equation is not appropriate in the lower-temperature range (T < T_g). The relaxation spectrum was calculated according to the first approximation method proposed by Schwarzl and Staverman. In addition to the α-transition region, a second transition zone is revealed at low temperature. This transition is probably due to a restricted motion of its main chain. © 1995 John Wiley & Sons, Inc.     

Synthesis and properties of organic soluble semicrystalline poly(aryl ether ketone)s copolymers containing phthalazinone moieties

A series of poly(aryl ether ketone)s (PAEK) copolymers containing phthalazinone moieties were synthesized by modest polycondensation reaction from 4‐(4‐hydroxyl‐phenyl)‐(2H)‐phthalazin‐1‐one (DHPZ), hydroquinone (HQ), and 1,4‐bis(4‐fluorobenzoyl)benzene (BFBB). The T_g values of these copolymers ranged from 168 to 235°C, and the crystalline melting temperatures varied from 285 to 352°C. By introducing phthalazinone moieties into the main chain, the solubility of these copolymers was improved in some common polar organic solvents, such as chloroform (CHCl₃), N‐methyl‐2‐pyrrolidinone (NMP), nitrobenzene (NB) and so on. The values of 5% weight loss temperatures were all higher than 510°C in nitrogen. The crystal structures of these copolymers were determined by wide‐angle X‐ray diffraction (WAXD), which revealed that they were semicrystalline in nature, and the crystal structure of these copolymers was orthorhombic, equal to poly(ether ether ketone ketone)s. As phthalazinone content in the backbone varied from 0 to 40 mol % (mole percent), the cell parameters of these copolymers including the a, b, and c axes lengths ranged from 7.76 to 7.99 Å, 6.00 to 6.14 Å, and 10.10 to 10.19 Å, respectively. The degree of crystallinity (via differential scanning calorimetry) decreased from 37.70% to 16.14% simultaneously. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 1744–1753, 2007     

Influence of annealing on structure of poly(aryl ether ether ketone ketone) revealed by SAXS

Structural studies of poly(aryl ether ether ketone ketone) (PEEKK) using small-angle X-ray scattering and one-dimensional electron density correlation function methods revealed that its aggregated state structure was significantly influenced by the annealing temperature. The long period L, the average thickness of the lamellae d, the electron density difference between the crystalline and amorphous regions η_c − η_a, and the invariant Q increased with increasing annealing temperature, but it was opposite to the case of the specific inner surfaces O_s. A transition zone existed between the traditional “two phases” with a dimension about 0.5 nm for semicrystalline PEEKK. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 69: 1829–1835, 1998