Synthesis of polyarylate through interfacial polycondensation by use of glycolyzed products of poly(ethylene terephthalate) glycolysis with bisphenol-a

The glycolysis of poly (ethylene-terephthalate) with bisphenol-A at certain ratios of PET/BPA was carried out in an autoclave reactor at different temperatures for varying periods of time. Then the glycolyzed products were utilized together with bisphenol-A for the synthesis of polyarylates through interfacial polycondensation. The polyarylates obtained (referred to as b/g-polyarylates in this article) possess good thermal characteristics but have lower mechanical strength than typical polyarylate synthesized from pure bisphenol-A by use of the same method. Blending the b/g-polyarylate with polycarbonate improved the impact strength significantly. As a whole, glycolysis with bisphenol-A followed by synthesis of polyarylate through interfacial polycondensation provided a feasible route for the reuse of poly(ethylene terephthalate).     

Synthesis of flexible polyarylate by interfacial polycondensation

Products with hydroxyl ends were synthesized from the esterification of bisphenol-A, terephthalic acid and ethylene glycol. These ester products were then used for synthesis of polyarylate by interfacial polycondensation. Not only the relative concentrations of reactants for esterification but also the conditions for interfacial polycondensation, such as the monomer ratio between two phases and the reaction time, play significant roles in affecting the properties of final products. Under proper synthesis conditions, the polyarylate formed could possess equivalent thermal characteristics and much higher impact strength in comparison with unmodified polyarylate due to the incorporation of flexible aliphatic segments from ethylene glycol. X-ray diffraction showed the existence of aliphatic segments would induce small degree of orderly alignment locally in structure.     

Miscibility in blends of liquid crystalline poly(p-oxybenzoate-co-p-phenyleneisophthalate) and polyarylate

The miscibility of liquid crystalline poly(p-oxybenzoate-co-p-phenyleneisophthalate) (HIQ35) and polyarylate (PAr) coprecipitated from a mixed solvent of phenol/tetrachloroethane was investigated with differential scanning calorimetry. It was found that the amorphous phase of HIQ35 and PAr formed a partially miscible blend at low concentration of HIQ35. No measurable interaction between HIQ35 and PAr occurred when the weight fraction of HIQ35 was close to or less than that of polyarylate, as evidenced by wide-angle X-ray diffraction results. Upon annealing at 315°C for several minutes, the apparent miscibility of HIQ35 with polyarylate appeared as a result of an initial reaction between the polymers. For longer annealing time, the thermal degradation of HIQ35 joined in the reaction. This reaction or degradation in the blend was confirmed by nuclear magnetic resonance analysis and the intrinsic viscosity measurement of the blend. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 68: 1581–1589, 1998     

Phase behavior of polyarylate blends

Melt mixtures of a polyarylate based on bisphenol A and tere/isophthalates were made with poly(ethylene terephthalate), several cyclohexane dimethanol-based polyesters, polycarbonate, and the poly(hydroxy ether) of bisphenol A. The phase behavior was determined using classical methods. With minimum time and temperature exposure, polyarylate exhibits phase separation with poly(ethylene terephthalate) (PET) at >30 wt % PET. With moderate time and temperature exposure, adequate ester exchange occurs with polyarylate/PET blends to yield single-phase behavior. The activation energy of the ester-exchange reaction was determined to be 37.0 kcal/mole. Under minimum time and temperature exposure conditions, miscibility of polyarylate with three different cyclohexane dimethanol-based polyesters was observed. A polyarylate-polycarbonate 50:50 mixture was shown to be phase separated under minimum mixing conditions but capable of exchange reactions to yield single-phase behavior with proper time and temperature exposure. Likewise, a 70:30 polyarylate-poly(hydroxy ether of bisphenol A) blend was phase separated as mixed, but with further elevated temperature exposure, a cross-linked single-phase system resulted. The density versus composition of the polyarylate-PET blends was linear with the phase-separated systems but exhibited a slight densification with the miscible systems produced by higher temperature exposure. The glass transition of the miscible polyarylate-polyester blends exhibited a significant deviation (lower) than predicted by a linear or Fox equation prediction. This was attributed to the low value of ΔC_p (specific heat difference between the glass and rubber states) of polyarylate as noted by the Couchman equation to be a major factor in the T_g versus composition relationship. The optical characteristics of the blends paralleled the observed phase behavior as single-phase blends were all transparent (in the amorphous state) whereas phase-separated blends were translucent to opaque. These results clearly demonstrate the importance of ester-exchange or transesterification reactions in the phase behavior of blends of polymers capable of these reactions.     

Partially miscible blends based on a polyarylate and poly(trimethylene terephthalate)

The miscibility of blends of a polyarylate (PAr) with poly(trimethylene terephthalate) (PTT) was investigated in the whole composition range by DSC measurements. With the exception of the 90/10 composition, which was fully miscible, the blends showed partial miscibility, and contained a nearly pure PTT phase and a PAr‐rich phase with 18% PTT. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1559–1561, 2004     

Morphology and physical properties of SAN/NBR blends: The effect of AN content in NBR

Poly(styrene‐co‐acrylonitrile) (SAN), of which the content of acrylonitrile (AN) repeating unit is 32 wt % (SAN32), was blended with poly(butadiene‐co‐acrylonitrile) (NBR). The effects of AN repeating unit content in NBR on the miscibility, morphology, and physical properties of SAN32/NBR (70/30 by weight) blends were studied. Differential scanning calorimetry and the morphology observed by transmission electron microscopy showed that the miscibility between SAN32 and NBR was increased as the AN content in NBR was increased up to 50 wt %. The impact strength and some other mechanical properties of the blends had the maximum value when the AN content in NBR was 34 wt %. In the measurement of viscoelasticity at melt state, SAN32/NBR blends showed yield behavior at low shear rate, and this behavior was most evident when the AN content in NBR was 34 wt %. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 1861–1868, 2000     

Phase behavior of binary mixtures of styrene/acrylonitrile copolymers and aliphatic polyesters

The phase behavior of binary mixtures of copolymers containing varying amounts of styrene and acrylonitrile (SAN) with a large range of aliphatic polyesters was examined. Miscibility was observed over a limited range of AN contents of the SANs, for each polyester, while similarly for each SAN, miscibility was only observed over a limited range of polyester molecular structures. Thermodynamic interaction parameters for the miscible blends were obtained by analysis of the depression of the polyester melting point. A binary interaction model was used to correlate the data and six group interaction parameters were deduced by subdividing the polyester and SAN copolymer repeating units in three different ways. It is concluded that there is a strong repulsion between the segmental units within the polyesters and within the SAN copolymers, which is an important factor in the observed phase behavior.     

Binary blends containing a commercial polyarylate

A commercial polyarylate (PAr), a copolyester of Bisphenol-A with 50 percent terephthalate-50 percent isophthalate, has been characterized by means of a combination of gel permeation chromatography and viscometry. It has been studied as first component of a series of polymer blends. The presence of either one glass transition temperature (T_g) or two has been used as a criterion to determine the miscibility of each blend. In some cases, the possible incidence of transesterification reactions has been considered.     

Miscibility of copolycarbonate blends with poly(styrene-co-acrylonitrile) copolymer and their interaction energies

The phase behavior of dimethyl polycarbonate-tetramethyl polycarbonate (DMPC-TMPC) blends with poly(styrene-co-acrylonitrile) copolymers (SAN) and the interaction energies of binary pairs involved in blend has been explored. DMPC-TMPC copolycarbonates containing 60 wt% TMPC or more were formed miscible blends with SAN containing limited amounts of AN. The miscibility of copolycarbonate with SAN decreases as the DMPC content increases. The miscible blends showed the LCST-type phase behavior or did not phase separate until thermal degradation. The binary interaction energies involved in the miscible blends were calculated from the phase boundaries using the lattice-fluid theory combined with binary interaction model. The phenyl ring substitution with methyl groups did not lead to interactions that are favorable for miscibility with polyacrylonitrile (PAN). The interaction energies of the polycarbonates blends with SAN copolymers as a function of AN content were obtained. It was revealed that the incline of the number of methyl groups on the phenyl rings of bisphenol-A unit acts favorably for the miscibility with SAN copolymer when SAN contains less than about 30 wt% AN and shifts the most favorable interaction to the low AN content.     

Effect of copolymer composition on the miscibility of blends of styrene-acrylonitrile copolymers with poly (methyl methacrylate)

The phase behaviour for blends of various polymethacrylates with styrene-acrylonitrile (SAN) copolymers has been examined as a function of the acrylonitrile content of the copolymer. Poly(methyl methacrylate), poly(ethyl methacrylate) and poly(n-propyl methacrylate) were found to be miscible with SANs over a limited window of acrylonitrile contents while no SANs appear to be miscible with poly(isopropyl methacrylate) or poly(n-butyl methacrylate). These conclusions were reached on the basis of lower critical solution temperature (LCST) and glass transition temperature behaviour. All miscible blends exhibited phase separation on heating, LCST behaviour, at temperatures which varied greatly with copolymer composition. An optimum acrylonitrile (AN) level ranging from about 10 to 14% by weight resulted in the highest temperatures for phase separation which has important implications for selection of SANs to produce homogeneous mixtures by melt processing. The basis for miscibility in these systems is evidently repulsion between styrene and acrylonitrile units in the copolymer as explained by recent models. The excess volumes for all blends are zero within experimental accuracy which suggests that the interactions for miscibility are relatively weak even for the optimum AN level. This interaction becomes smaller the larger or more bulky is the alkyl side group of the polymethacrylate.     

Molecular-level free volume as a crucial complementary factor affecting miscibility and nanoscopic homogeneity of polyarylate/poly(vinyl chloride) blends

Molecular-level miscibility and scale of mixing were characterized and evaluated for three model blends of polyarylates having structural variants with PVC through cross polarization/magic-angle spinning (CP/MAS) ¹³C nuclear magnetic resonance (NMR) spectroscopy. From this study, we found that the polyarylate with sulfonyl central connector and tetramethyl substitutions on bisphenol rings (shortly, TMBPS-PAr) was nanoscopically miscible with PVC as homogeneously mixed down to a scale of ∼2.3 nm. In contrast, the structurally similar polyarylate, just in absence of tetramethyl substitutions from TMBPS-PAr, (BPS-PAr) was partially mixed with PVC at a homogenization scale of at least ∼27-32 nm, regardless of almost identical specific intermolecular interaction relative to TMBPS-PAr. In the case of polyarylate with isopropyl central connector other than the sulfonyl (TMBPA-PAr) was found to be completely immiscible with PVC, despite the presence of tetramethyl substitutions, due to the lack of polar sulfonyl groups that is known to promote mixing. These observations, in conjunction with the structural combinations of polyarylates, suggest the need to seek another complementary key parameter to promote miscibility and nanoscopic homogeneity in addition to the specific interaction. From the results of the positron annihilation analysis (PALS) on the intermolecular free volume through the entire composition ratio, the TMBPS-PAr/PVC blend resulted in a larger negative deviation of the ortho-positronium (o-Ps) pick-off lifetimes (τ₃) and the free cavity sizes (R) from linear additivity of those parameters of component polymers compared to the BPS-PAr/PVC blend. The larger negative deviation was interpreted to be a higher/greater contraction of free space and more tightly packing of molecular chains in TMBPS-PAr/PVC upon mixing irrespective of similar specific intermolecular interaction between two blend systems, which shows good agreement with the results of densities with blend compositions. Recognizing that the only structural variation between TMBPS-PAr and BPS-PAr was tetramethyl substitutions and that TMBPA-PAr/PVC was completely immiscible despite the tetramethyl substitutions, the combined results obtained from NMR and PALS lead to rationalize additional effects of the molecular free volume space created by the tetramethyl groups on the good miscibility of the blends under the circumstance when enough specific intermolecular interaction existed upon mixing.     

Miscibility behaviour of bisphenol-A polycarbonate and poly(para-chlorostyrene)

The miscibility behaviour of bisphenol-A polycarbonate (PC) and poly(para-chlorostyrene) (PpCIS) has been investigated. Special attention has been paid to the influence of the molar mass of PpCIS. Molar masses varying from 10 to > 1,000 kg/mol were used. The blends were studied by differential scanning calorimetry (DSC), dynamic mechanical thermal analysis (DMTA), and scanning and transmission electron microscopy (SEM and TEM). It was concluded that the blends of all three PpCIS grades and PC phase separate. In the low concentration region, some intermixing was found, especially for the blend with the low molar mass PpCIS. The most important effect of lowering the molar mass of PpCIS was an acceleration of the phase separation. The combination of SEM with electron probe X-ray microanalysis (EPMA) gave qualitative information on the miscibility behaviour and was found to be a useful extension of routine microscopy techniques used in blend studies.     

Transesterification reaction of polyarylate and copolyester (PETG) blends

Transesterification reactions between polyarylate (PAr) and a copolyester (PETG) have been investigated by proton nuclear magnetic resonance (NMR), Fourier-transform infrared spectroscopy (FTIR), and differential scanning calorimetry. Blends of PAr and PETG were prepared by melt mixing and solution-casting with weight fractions of PAr in the blends varying from 0.90 to 0.10. The PETG is a copolyester containing ethylene-1,4-cyclohexylene dimethylene terephthalate. From the thermal analysis of the PAr/PETG melt blends, a single glass transition temperature is observed, which indicates a miscibility between the PAr and PETG. The benzene insoluble fraction of the PAr/PETG (50/50) melt blends and solution-cast blends were characterized using NMR and FTIR. The results of NMR and FTIR support the conclusion that transesterification reactions between the PAr and PETG occurred under the melt blending conditions applied.     

Miscibility of polyethyloxazoline with thermoplastic polymers

Polyethyloxazoline (PEOx) blends with several other thermoplastic polymers were examined by differential scanning calorimetry (DSC) for miscibility. Styrene/acrylonitrile (SAN) copolymers having compositions in the range of about 20–40% acrylonitrile (AN) by weight were found to be miscible with PEOx whereas SANs outside this range were not. The polyhydroxyl ether of bisphenol A (Phenoxy) was also found to be miscible with PEOx. A vinylidene chloride copolymer (Saran) was found to be partially miscible with PEOx, whereas poly(methyl methacrylate) and polycarbonate were not miscible at all.     

Water absorption and its effect on polyarylate

Water absorption and its effect on the tensile and impact properties of polyarylate was studied by immersing polyarylate specimens in water baths, between 23 and 98°C. The diffusivity was calculated to be 11 × 10^?9 cm²/s at 23°C with an activation energy of 9.8 kcal/mole. The aromatic ester in polyarylate is hydrolyzed by water, which was found to cause a decrease in molecular weight and in mechanical properties. In the early stage, the reaction is zero-order and the activation energy of the hydrolytic embrittlement is 22 kcal/mole.     

Solid state and mechanical properties of injection molded poly(ether ether ketone)/polyarylate blends

Blends of poly(ether ether ketone) (PEEK) and bisphenol-A polyarylate (PAr) were directly prepared during the plasticization step of an injection molding machine and their solid-state and mechanical behaviors were studied. Despite the fact that PEEK-rich blends were apparently miscible by differential scanning calorimetry (DSC), from the dynamic-mechanical analysis (DMTA) results all the blends were composed of (a) a crystalline PEEK phase, (b) a practically pure amorphous PEEK phase, and (c) a PAr-rich phase richer in PEEK as the PEEK content in the blends increased. Annealed blends showed a poor mechanical performance in the PAr-rich region, but the PEEK-rich blends showed additive modulus of elasticity and tensile strength, and ductility and impact strength values similar to those of the highest of the two pure components. All the as-molded low-crystalline blends presented a synergistic behavior in the modulus of elasticity, as well as, surprisingly, in ductility and impact strength in the intermediate and slightly majority PEEK compositions. The different mechanical response of the components in fine dispersed phases and in macroscopic tensile specimens may account for the observed results.     

Phase behavior studies of polyarylate/copolyester blends by thermal and dynamic mechanical analysis

The phase behavior of polyarylate blends with a copolyester based on poly(1,4-cyclohexanedimethylene/ethylene terephthalate) was studied by differential scanning calorimetry and dynamic mechanical analysis. A single glass-transition temperature was observed over the entire composition range. Up to 30% weight polyarylate, the copolyester crystallized readily and its melting point did not change with blend composition. This indicates that transesterification, if it occurred, was negligible. The thermal and dynamic results also suggest a weak polymer-polymer interaction in this system.     

Effect of molecular structure of polyarylates on the compatibility in polyarylate/poly(vinyl chloride) blends

A homologous series of polyarylates were prepared by condensation polymerization of three different bisphenols, isophthaloyl, and terephthaloyl chlorides (their molar ratio = 2:1:1). The resulting polyarylates were tetramethyl bisphenol S– (TMBPS–), bisphenol S– (BPS–), and tetramethyl bisphenol A– (TMBPA–) polyarylates, and each have structural variants; (1) methyl or no substitution on the biphenyl rings of bisphenol, and/or (2) central group connecting the biphenyl rings with or without polarity. Only the polyarylate having both methyl substitution and polar connector, i.e., TMBPS–polyarylate, was found to be compatible with PVC. The sulfone groups of TMBPS–polyarylate and chlorides of PVC exerted a dipole–dipole interaction only when the tetramethyl substitution on the bisphenol rings was present. In the absence of tetramethyl groups (BPS–polyarylate), incompatibility with PVC was observed. The strength of polar interactions appeared to be influenced by the methyl substitution causing electronic rearrangement in bisphenol rings. However, due to the lack of polar connector groups, the inclusion of methyl substitution in TMBPA–polyarylate was found to have no effect on the specific interactions, and hence, the compatibility with PVC. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 70: 2173–2180, 1998     

双酚A人工抗原的合成与表征

双酚A经过重氮化引入羧基,再经碳化二亚胺法与牛血清白蛋白偶联,成功合成了双酚A人工抗原,为其免疫分析方法的建立打下了基础.产物经红外和紫外光谱分析确证.     

Effect of chlorination and bromination on the dielectric characteristics of bisphenol-A polyesters

The variation of dielectric behaviour with temperature of three crosslinked polyester resins based on the condensates of chloro-methyl acetate and bisphenol-A, 2,2-di-(4-hydroxy 3,5-dichloro phenyl) propane and 2,2-di-(4-hydroxy 3,5-dibromo phenyl) propane were studied in the microwave frequency region at wave length 3.21 cm. The dielectric constants of these polyesters are 2.93, 2.91 and 2.77 respectively and do not change with temperature in the 30–85°C region. The decrease in dielectric constant after incorporating 2,2-di-(4-hydroxy 3,5-dichloro phenyl) propane and 2,2-di-(4-hydroxy 3,5-dibromo phenyl) propane in the polyester chain is attributed to the decrease in the number of ester and ether groups in the polyester chain per unit weight of the cured polyesters. It is found that the loss factor for bisphenol-A based polyester resin is maximum at 55°C and the relaxation time of this polyester is 1–7 · 10^-11 sec at 55°C. It can be assigned to the free motion of ether linkages due to the absence of halide groups at 3,5 position of bisphenol-A incorporated in the polyester chain. This can also be attributed to the absence of secondary forces between the chains due to the presence of bulky p-phenylene groups in the polyester chain and crosslinking by bulky molecules like styrene. In case of chlorinated and brominated polyesters, the motion about ether and ester linkages is difficult. The chlorinated bisphenol-A polyester has less variation in loss factor as compared to that of bromo polyester. It may be due to the homo polystyrene or large polystyrene segments present in bromo polyester. These results are also supported by the studies on hydrolytic stability of their base resins and by the heat distortion point of the crosslinked polyesters.