The synthesis,characterization, and weathering behavior of polycarbonates derived from 3,3′-dihydroxydiphenyl ether

Previous studies of the photodegradation of bisphenol A polycarbonate (BPA PC) indicate that both alkyl side chain and ring oxidation play significant roles. In order to determine the relative importance of these two pathways in the photoyellowing that accompanies photodegradation, side chain free polycarbonates based on 3,3′-dihydroxydiphenyl ether were synthesized and tested. Both accelerated weathering experiments using a QUV test apparatus and outdoor weathering indicated that these polymers photoyellowed faster than BPA PC. This suggests that ring oxidation is an important source of photoyellowing of aromatic polycarbonates.     

Synthesis and Characterization of a Novel Copoly(aryl ether ketone) Containing 4, 4''''-Biphenyl-bis[4-phthalazin-1(2H)-one] Moiety

Poly(aryl ether ketone)s are a category of high performance engineering thermoplastics characterized by high glass transition temperature and excellent thermooxidative stability. And they have important applications in electronic, electric, aircraft and aerospace industries1~3. Considerable efforts have been made towards the improvement of solubility or processability of poly(aryl ether ketone)s4,5. In our work, a novel bis(phthalazinone) monomer 1 4, 4-biphenyl-bis[4-phthalazin-1(2H)-one] …     

Influence of photo-Fries reaction products on the photodegradation of bisphenol-A polycarbonate

The photodegradation of BPA polycarbonate (PC) can be described as an autoaccelerating process initiated by the formation of biphenol products arising from a formal photo-Fries reaction pathway. Evidence comes from spiking PC films with model compounds of photo-Fries reaction products, pre-exposure of films to generate photo-Fries products, and kinetic analysis. Published data on products formed during natural PC weathering are consistent with this pathway.     

Chemical recycling of polycarbonate in high pressure high temperature steam at 573 K

Polycarbonate (PC) could be completely decomposed into its monomer, bisphenol A (BPA) with high pressure (not atmospheric pressure) high temperature steam (573 K) in 5 min reaction time. The maximum yield of BPA was about 80 mol% based on the starting PC. PC decomposition at 573 K in liquid water phase near the saturated pressure for the comparison. For 30 min in reaction in liquid water at 573 K residual PC still remained and the BPA yield was about 50% as maximum.     

Thermal degradation processes of poly(carbonate) and poly(methyl methacrylate) in blends coalesced either from their common inclusion compound formed with γ-cyclodextrin or precipitated from their common solution

Direct insertion probe pyrolysis mass spectrometry (DIP-MS) analyses of a PC/PMMA blend, coalesced from their common inclusion compound (ICs) formed with host γ-cyclodextrin (γ-CD) through removal of the γ-CD host, and a physical PC/PMMA blend, precipitated from their common solution, have been performed and compared with those of the coalesced and as-received homopolymers. A slight increase in the thermal stability of the PMMA component in the presence of PC was recorded both by TGA and DIP-MS compared to the corresponding homopolymers. The DIP-MS observations pointed out that the thermal stability and degradation products of these polymers are affected once they are included inside the IC channels created by the stacked host CDs. DIP-MS observations suggested that for both coalesced and physical PC/PMMA blends, an exchange reaction occurs between carbonates of PC and MMA, formed by depolymerization of PMMA above 300 °C, most likely due to diffusion of MMA monomer at the interface or even into the PC domains, where it can react producing low molecular weight PC bearing methyl carbonate and methacrylate chain ends. The results also indicated an ester-ester interchange reaction between PC and PMMA yielding a graft copolymer and low molecular weight PC chains bearing methyl carbonate end groups in the case of the coalesced blend. This can be atttributed to the presence of specific molecular interactions between the intimately mixed PMMA and PC chains in the coalesced PC/PMMA blend.     

Dielectric studies of tetraaryl and triaryl polycarbonates and comparisons with bisphenol A‐polycarbonate

The relative permittivity, loss, and breakdown strength are reported for a commercial sample of bisphenol A‐polycarbonate (comm‐BPA‐PC) and a purified sample of the same polymer (rp‐BPA‐PC) as well as for two new polycarbonates having low molecular cross‐sectional areas, namely a copolymer of tetraaryl polycarbonate and BPA‐PC (TABPA‐BPA‐PC) and a triaryl polycarbonate homopolymer (TriBPA‐PC). The glass transition temperatures of the new polymers are higher than the T_g of BPA‐PC (187 and 191 °C vs. 148 °C). Relative permittivity and loss measurements were carried out from 10 to 10⁵ Hz over a wide temperature range, and results for the α‐ and γ‐relaxation regions are discussed in detail. For the α‐relaxation, the isochronal peak position, T_α, scales approximately with T_g. On the other hand, the peak temperature for the γ‐relaxation is approximately constant, independent of T_g. Also, in contrast to what is observed for α, γ exhibits a strong increase in peak height as temperature/frequency increases and a significant difference is found between Arrhenius plots determined from isochronal and isothermal data analyses. Next, the γ‐relaxation region for comm‐BPA‐PC and associated activation parameters show strong history/purity effects. The activation parameters also depend on the method of data analysis. The results shed light on discrepancies that exist in the literature for BPA‐PC. The shapes of the γ loss peaks and hence glassy‐state motions for all the polymers are very similar. However, the intensities of the TriBPA‐PC and TABPA‐BPA‐PC γ peaks are reduced by an amount that closely matches the reduced volume fraction of carbonate units in the two new polymers. Finally, for comm‐BPA‐PC, the breakdown strength is strongly affected by sample history and this is assumed to be related to volatile components in the material. It is found that the breakdown strengths for TriBPA‐PC and TABPA‐BPA‐PC are relatively close to that for rp‐BPA‐PC with the value for TriBPA‐PC being slightly larger than that for rp‐BPA‐PC or the value usually reported for typical capacitor grade polycarbonate. Finally, it is shown that the real part of the relative permittivity remains relatively constant from low temperatures to T_g. Consequently, based on the dielectric properties, TriBPA‐PC and TABPA‐BPA‐PC should be usable in capacitors to at least 50 °C higher than BPA‐PC. © 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2011     

Effects of irradiation conditions on the weathering of engineering thermoplastics

The nature of the light source and its intensity can be important variables in accelerated weathering of aromatic engineering thermoplastics. Activation spectra show that BPA polycarbonate (PC) and its blends are very sensitive to UV with wavelengths <300 nm, as is well-known in the literature, but other resins gave unremarkable results. Xenon arc weathering experiments performed under identical conditions, but with different filter combinations did not show consistent rate enhancements. For 48 samples across a range of aromatic engineering thermoplastics, conditions using borosilicate inner and outer filters were 1.7× harsher than the CIRA/soda lime filter combination. However, the range was 1.0-2.5 and the standard deviation was approximately 0.35 making the correlation 1.7 ± 0.7 at 95% confidence level for any given sample. The quartz/borosilicate combination used in SAE J1960 was 2.3× harsher than CIRA/soda lime conditions, but the standard deviation was 1.1 making the correlation 2.3 ± 2.2 at the 95% confidence level for any given sample. The effects of irradiance level and the dark cycle were determined in order to establish the legitimacy of accelerated testing methods. Linear increases in degradation with increased irradiance were observed for PC, poly(butylene terephthalate), and blends of PC with other polymers. Some non-linearity was found for styrene acrylonitrile copolymer (SAN), and extreme non-linearity was found for ABS. No effect was found from a light/dark cycle other than the rate reductions expected from the lower dose rate. Thus, for accelerated weathering of engineering thermoplastics, the best possible match for sunlight is required, but increasing the intensity and decreasing or eliminating the dark period are permissible for most aromatic thermoplastic resins.     

Aging behavior and mechanism of ethylene-propylene-diene monomer (EPDM) rubber in fluorescent UV/condensation weathering environment

Ethylene-propylene-diene monomer (EPDM) rubber was exposed to an artificial weathering environment produced by fluorescent UV/condensation weathering device for different time periods. The surface chemical changes were detected by X-ray Photoelectron Spectroscopy (XPS) and Raman spectroscopy. The plausible aging mechanism of EPDM was proposed. The surface energy was calculated through contact angles of water and formamide measured by optical contact angle measuring device. The thermal stability was evaluated by thermo-gravimetric analysis (TGA).The results showed that oxygenated species such as C-O-C, CO and O-CO groups were formed in fluorescent UV/condensation weathering environment. EPDM aging occurred from EPDM surface and propagated to EPDM inner body. The surface energy of EPDM increased to a maximum at 36 days of aging and then decreased slowly. Fluorescent UV/condensation weathering environment does not affect the thermal stability of EPDM predominantly.     

含1,2-亚乙基单元的双酚A聚碳酸酯非光气法合成和表征

以双酚A(BPA),碳酸乙二酯(EC)和碳酸二甲酯(DMC)为原料,制备双酚A二元醇(Ⅰ)和双酚A碳酸酯(Ⅱ),并用红外光谱与核磁共振波谱对其结构进行表征.通过Ⅰ与Ⅱ的共缩聚反应及Ⅱ的自聚实现了主链中含有—CH2CH2—单元的双酚A型聚碳酸酯(PC)的非光气法合成,用凝胶渗透色谱法(GPC)和TGA-DSC对PC的分子量和热性质进行分析.结果表明,Ⅱ在240℃自聚6h后产物的Mn可达17.6×103,主链中—CH2CH2—单元的引入,可以降低聚合物的Tg,提高其结晶性,所得聚合物具有良好的热稳定性.     

Electrochemical sensor based on f-SWCNT and carboxylic group functionalized PEDOT for the sensitive determination of bisphenol A

A simple,sensitive,and reliable method for the voltammetric determination of bisphenol A(BPA) by using carboxylic group functionalized single-walled carbon nanotubes(f-SWCNT)/carboxylic-functionalized poly(3,4-ethylenedioxythiophene)(PC4) complex modified glassy carbon electrode(GCE) has been successfully developed.The electrochemical behavior of BPA at the surface of the modified electrode is investigated by electrochemical techniques.The cyclic voltammetry results show that the as-prepared electrode exhibits strong catalytic activity toward the oxidation of BPA with a well-defined anodic peak at 0.623 V in PBS(0.1 mol/L,pH 7.0).The surface morphology of the 3D network of composite film is beneficial for the adsorption of analytes.Under the optimized conditions,the oxidation peak current is proportional to BPA concentration in the range between 0.099 and 5.794 μmol/L(R~2 = 0.9989),with a limit of detection of 0.032 μmol/L(S/N = 3).The enhanced performance of the sensor can be attributed to the excellent electrocatalytic property of/-SWCNT and the extraordinary conductivity of PC4.Furthermore,the proposed modified electrode displays high stability and good reproducibility.The good result on the voltammetric determination of BPA also indicates that the asfabricated modified electrode will be a good candidate for the electrochemical determination and analysis of BPA.     

Preparation and characterisation of novel random copoly(arylene ether-thioether ketone)s containing 2,2-bis(4-phenylene)propane units

This study investigates on the preparation and characterisation of new random copolymers containing the monomeric units of a poly(arylene ether ketone) (PEAEK) and a poly(arylene thioether ketone) (PTATK) previously synthesised by our group. The syntheses were performed using a one-pot polymerisation method starting from 4,4′-difluorobenzophenone, bis(N,N-dimethyl-S-carbamate) of 2,2-bis(4-mercaptophenyl)propane (MBTA) and bisphenol A (BPA). Different mole percentages of BPA with respect to MBTA, varying from 20% to 80%, were used. The copolymers, obtained in good yields, have molecular weights in the range from 19,000 to 32,000 as determined by GPC. The structural proof is provided by ¹H NMR spectroscopy. The TGA analysis shows that the high stability of PEAEK is only slightly affected by the introduction of the PTATK co-units in the chain. Indeed, the presence of sulphur atoms induces an initial degradation process at temperatures slightly lower than that of PEAEK, but in a second stage tends to improve the formation of crosslinkings. Moreover, the copolymers with an amount of PEAEK equal to 40 and 20 mol% show a small crystallinity, due to the presence of PTATK units. The T_g values are not affected by the composition of copolymers. Therefore, the presence of sulphur atoms in the polymer backbone does not significantly modify the PEAEK characteristics, whereas can induce important new properties, such as better flame resistance or higher refractive index.     

Anionic bulk oligomerization of ethylene and propylene carbonate initiated by bisphenol‐A/base systems

When the bulk oligomerization of 1,3‐dioxolan‐2‐one (ethylene carbonate, EC) and 4‐methyl‐1,3‐dioxolan‐2‐one (propylene carbonate, PC) with the 2,2‐bis(4‐hydroxyphenyl)propane (bisphenol‐A, BPA)/base system (bases such as KHCO₃, K₂CO₃, KOH, Li₂CO₃, and t‐BuOK) was investigated at elevated temperature, significant differences were observed. Oligomerization of EC initiated by BPA/base readily takes place, but the oligomerization of PC is inhibited. The very first propylene carbonate/propylene oxide unit readily forms a phenolic ether bond with the functional groups of BPA phenolate, but the addition of the second monomer unit is rather slow. The oligomerization of EC yields symmetrical oligo(ethylene oxide) side chains. According to IR studies the oligomeric chains formed from PC with BPA contain not only ether but also carbonate bonds. The in situ step oligomerization of the BPA dipropoxylate was also identified by SEC, and a possible reaction mechanism is proposed. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 545–550, 1999     

Adsorption of roxarsone from aqueous solution by multi-walled carbon nanotubes

Molecularly imprinted particle for bisphenol A (BPA-MIP) was prepared using the surface molecular imprinting technique with a sol-gel process on the surface of silica nanoparticles. The dosages of diethylenetriaminepentaacetic acid (DTPA) as a functional monomer and teraethyl orthosilicate (TEOS) as a cross-linker were optimized, respectively. The prepared BPA-MIP was characterized by scanning electron microscopy (SEM), energy dispersive spectrometer (EDS), Fourier transform infrared spectrometer (FTIR), thermogravimetric analysis (TGA), and a standard Brunauer-Emett-Teller (BET) analysis. Moreover, the proper binding and selective recognition ability were also investigated by a single batch binding experiment. The equilibrium data fitted well to the pseudo-second-order kinetic and the Langmuir model for BPA binding onto BPA-MIP, respectively. The saturate binding capacity of BPA-MIP was found to be 30.26 μmol g(-1), which was three times higher than that of BPA non-molecular imprinted particle (BPA-NIP). The satisfactory results demonstrated that the obtained BPA-MIP showed an appreciable binding specificity toward BPA than similar structural compounds in water phase. The BPA-MIP could serve as an efficient selective material for determining or removing BPA from water environment.     

聚硅芳撑硅氧烷的研究(Ⅱ)——聚四甲基对硅苯撑硅氧烷的合成

本文以具有硅苯撑结构的环状有机硅氧烷--十二甲基环三对硅笨撑硅氧烷为单体,用开环聚合方法合成了聚四甲基对硅苯撑硅氧烷.选用硅醇钾催化,环单体有较高的开环聚合活性.通过IR、¹H NMR和¹³C NMR等证明了聚合物的化学结构.聚合物在空气中的热失重温度较聚二甲基硅氧烷约高110℃,因此热稳定性更好.     

SYNTHESIS AND CHARACTERIZATION OF THERMOTROPIC COPOLYESTERS AND COPOLY (ESTER-AMIDE)S CONTAINING OXYETHYLENE-ETHER AS THE SPACER

Flexible oxyethylene-ether was introduced into the aromatic copolyesters and copoly(es-ter-amide)s to reduce the melting point of resulting polymers. The melting point was greatlyreduced to 200℃ or even lower in some cases, and the molecular weight was satisfactorilyhigh as reflected by inherent viscosity. The polymers exhibited high thermal stability and goodmechanical properties as determined by TGA and mechanical tests. The copolyester showedbetter crystallinity and liquid crystallinity than corresponding copoly(ester-amide)s with simi-lar monomer composition as reflected by POM observation and WAXD study. The meltingpoints for both copolyesters and copoly (ester-amide)s showed great dependence on the p-acetoxybenzoic acid (PAB) content in monomer composition and reached the lowest valuewhen PAB was 29 mol%.     

Effects of plastic additives on depolymerization of polycarbonate in sub-critical water

The effects of plastic additives on depolymerization of polycarbonate (PC) in sub-critical water were examined. Depolymerization of PC with two additives was carried out in an autoclave at temperatures from 533 to 613 K for reaction times ranging from 15 to 60 min. The additives used were a flame retardant (decabromodiphenyl ether, DBDPO) and a plasticizer (di-n-octyl phthalate, DnOP). The main products of PC depolymerization in the presence or absence of the additives were bisphenol A (BPA) and phenol, which were identified by Fourier-transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), and gas chromatography mass spectrometry (GC-MS), and quantified by gas chromatography (GC). The addition of DBDPO accelerated the hydrolysis of PC while the addition of DnOP had the opposite effect, and both additives reduced the yield of BPA. The activation energy for PC depolymerization in sub-critical water was found to be lower with DBDPO additive than with DnOP.     

Effects of oxygen plasma treatment on the surface of bisphenol A polycarbonate: a study using SIMS,principal component analysis,ellipsometry, XPS and AFM nanoindentation

The effects of oxygen plasma treatment and the subsequent air exposure on the surface composition and properties of bisphenol A polycarbonate (BPA‐PC) were analysed by X‐ray photoelectron spectroscopy (XPS), ellipsometry, static time‐of‐flight secondary ion mass spectrometry (ToF‐SIMS) with principal component analysis (PCA) and nanoindentation using an atomic force microscope (AFM). PCA showed systematic changes in the film chemistry after short treatment times (0.1 s), with the main sites of attack being the carbonate and aromatic ring structure. On the basis of this multitechnique analysis, it was unambiguously determined that extended oxygen plasma treatment times resulted in the formation of low‐molecular‐weight material (LMWM) within the first 50 nm on the surface, and not in a cross‐linked skin as has been proposed by other researchers. The study shows that controlled surface modification of BPA‐PC polymers is possible, allowing surface oxygen incorporation without degradation of the polymer structure. This result is relevant for improved adhesion of coatings applied to BPA‐PC polymers. Copyright © 2006 John Wiley & Sons, Ltd.     

Radiation-grafting of 2-hydroxyethylmethacrylate and oligo (ethylene glycol) methyl ether methacrylate onto polypropylene films by one step method

Polypropylene films were modified with 2-hydroxyethylmethacrylate (HEMA) and oligo (ethylene glycol) methyl ether methacrylate (OEGMA) using the pre-irradiation method with gamma-rays (one step method). The effect of absorbed dose from 10 to 100 kGy, temperature (50, 60, and 70 °C), monomer concentration between 12.5% and 62.5%, monomers ratio from 10% to 90% and reaction time from 5 to 50 h; on the degree of grafting was determined. The grafted samples were analyzed by FTIR-ATR, TGA, DSC, swelling, and contact angle. Grafts onto polymeric films between 3% and 109% were obtained at doses from 10 to 100 kGy and a dose rate around 7.4 kGy/h. The graft percent increased with the content in HEMA in the HEMA:OEGMA feed mixture, which indicates a lower reactivity of OEGMA compared to HEMA. The hydrogel layer grafted on the polypropylene substrate increases the hydrophilicity of the surface and also provides certain temperature-responsiveness, which may be of interest for biomedical applications.     

Cetyltrimethylammonium Bromide(CTAB)-Ionic Liquid Composite Modified Electrode for Sensitive Cyclic Voltammetric Determination of Bisphenol A

A sensitive electrochemical sensor for determining bisphenol A(BPA) was designed. The sensor was a glassy carbon electrode modified with the surfactant cetyltrimethylammonium bromide and the ionic liquid 1-decyl-3-methylimidazolium tetrafluoroborate. The ability of the new sensor to measure BPA was investigated in cyclic voltammetry experiments. Under optimized conditions, the sensor gave a linear response range for BPA of 2.19×10^-7-3.28×10^-5 mol/L and a detection limit of 7.31×10^-8 mol/L(S/N=3). BPA could be determined with a lower detection limit, a wider linear range, and more sensitivity using the sensor than using other electrochemical sensors or high performance liquid chromatography with UV detection. The new sensor was used to determine BPA in tap water with recoveries of 97.5%-98.7% and a relative standard deviation <2.9%. The results show that the sensor can be used to determine trace BPA concentrations in tap water.     

The impact of resorcinol bis(diphenyl phosphate) and poly(phenylene ether) on flame retardancy of PC/PBT blends

Flame retardancy of bisphenol A polycarbonate (PC)/poly(butylene terephthalate) (PBT) blends was improved by the addition of resorcinol bis(diphenyl phosphate) (RDP) and poly(phenylene ether) (PPO). A PC/PBT blend at 70/30 weight ratio obtained a V‐0 rating by the addition of 10 wt% RDP and 10 wt% PPO. The combination of 5 wt% methyl methacrylate‐butadiene‐styrene tercopolymer (MBS) with 3 wt% ethylene‐butylacrylate‐glycidyl methacrylate tercopolymer (PTW) causes a remarkable increase in toughness of the PC/PBT/RDP blend while maintaining a high rigidity. A detailed investigation of the flame‐retardant action of PC/PBT/RDP and PC/PBT/RDP/PPO blends was performed using thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), TGA‐FTIR, temperature‐programmed pyrolysis/gas chromatography/mass spectrometry (TPPy/GC/MS), and scanning electron microscopy/energy dispersive spectrometer (SEM/EDS). The results demonstrate that RDP induces a higher char yield at ca. 450 °C and synchronously increases the thermal stability of the blend with PPO. The flame‐retardant role of RDP in the condensed phase was discerned from TGA, FTIR, and SEM/EDS of the residues. Copyright © 2010 John Wiley & Sons, Ltd.