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1.
A series of diphenylquinoxaline‐containing polyamides were prepared from the condensation polymerization of 2,3‐bis (4‐bromophenyl) quinoxaline (DBQ) with various primary and secondary diamides via copper‐catalyzed amidation reaction. The polyamides were characterized with FTIR, NMR, GPC, differential scanning calorimeter, and thermo gravimetric analysis, and their solubility and viscosity were measured. The polyamides synthesized here are amorphous and showed relatively good solubility in polar aprotic solvents and demonstrate the ability to form brownish hard films by solvent casting; their inherent viscosities ranged from 49 to 55 mL/g. The average molecular weights of polyamides were in the range of Mw = 11,950–5592 g/mol (MWD = 1.21–1.87). These polyamides had relatively high thermal stability with Tg values up to 276°C, 10% weight loss temperatures (T10%) in the range of 364–476°C, and char yields at 600°C in N2 up to 72%. They also exhibit emission in the solid state and in dilute (0.2 g/dL) DMAc solution at 425–484 nm with photoluminescence quantum (?f) yields in the range of 14–23%. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012  相似文献   

2.
The thermal properties of a set of experimental aliphatic–aromatic polyamides containing ether linkages were examined as a function of their chemical structure. Variations of the glass transition temperature (Tg) and melting temperature (Tm) could be correlated with the length of the aliphatic spacers and with the orientation of the phenylene rings. Polymers with a high concentration of p-oriented phenylene units showed a higher Tg than those containing mainly m-oriented ones; Tg values ranged from 110 to 155°C. Surprisingly, a negligible dependence of Tgs on the nature of flexible spacers was observed. For all of the polymers, the thermal stability was virtually the same, about 440°C, when tested by dynamic thermogravimetric analysis (TGA). However, quite different levels of thermal stability were found by isothermal TGA analysis for polyamides with different flexible spacers. Moreover, the poly(ether-amide)s described here compare fairly well with wholly aromatic polyamides when measured by dynamic TGA; but isothermal TGA measurements clearly demonstrated that they decompose faster than aromatic polyamides. Treatment of the TGA curves by the method of McCallum provided kinetic data that confirmed a better long-term stability for poly(ether-amide)s with a higher proportion of para-oriented phenylene rings. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 67:975–981, 1998  相似文献   

3.
High-molecular-weight poly(p-arylene sulfide ketone) (PPSK) was prepared by nucleophilic substitution reaction of 4,4’-diflurobenzophenone (DFBP) and sodium sulfide in the compound solvents of diphenyl sulfone (DPS) and 1,3-dimethyl-2-imidazolidinone (DMI) with catalysts under elevated temperature. The inherent viscosity (ηint) of the PPSK synthesized was 0.703 dl/g. PPSK was characterized by Fourier-transform infrared spectroscopy, elemental analysis, x-ray diffraction, differential scanning calorimetry, and thermogravimetric analysis. It was found that the polymer had excellent thermal properties: glass transition temperature (Tg) was 142.8 °C, melting temperature (Tm) was 362.3 °C. Under nitrogen atmosphere, 5 % (T5%) and 10 % (T10%) weight-loss temperatures were about 498.5 °C and 526.2 °C, respectively, while in the air the T5% and T10% were about 517 °C and 535.8 °C, respectively. The PPSK was found to be a semi-crystalline polymer, as confirmed by XRD. The polymer was insoluble in any solvent except concentrated sulfuric acid at room temperature. A series of the PPSK separating membranes were prepared by dissolving PPSK to concentrated sulfuric acid. The fluxes and the porosities of the separating membranes were in the range of 230–43 L/(m2?·?h) and 77.7-84.7 %, respectively. At the same time, these separating membranes showed moderate tensile strength of 1.02-1.88 MPa.  相似文献   

4.
2,7‐Dibromo‐9,9‐dioctylfluorene was synthesized by a two‐step reaction from fluorene and n‐octylboromide. This was reacted with benzamide for the preparation of a model compound and with terephthalamide, isophthalamide, and adipamide for the preparation of polyamides in the presence of a mixture of 10 mol % CuI and 20 mol % N,N′‐dimethylethylenediamine as a catalyst and K2CO3 as a base. The monomer and the model compound were characterized with Fourier transform infrared, proton nuclear magnetic resonance, and elemental analysis. The prepared polyamides were characterized with Fourier transform infrared, proton nuclear magnetic resonance, differential scanning calorimetry, thermogravimetric analysis, and solubility and viscosity measurements. The obtained polyamides possessed excellent solubility in common organic solvents, and they exhibited inherent viscosities in the range of 0.93–1.19 dL/g. According to the differential scanning calorimetry analysis, the glass‐transition temperatures of the polyamides were in the range of 84–154°C. Thermogravimetric analysis indicated that a 2% weight loss of the polyamides occurred in the temperature range of 218–253°C under a nitrogen atmosphere. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009  相似文献   

5.
Thermal properties of poly(phenylene sulfide amide) (PPSA) prepared using sodium sulfide, sulfur, and thiourea as sulfur sources which reacted with dichlorobenzamide (DCBA) and alkali in polar organic solvent at the atmospheric pressure, were studied. The glass transition temperature (Tg), melting point temperature (Tm), and melting enthalpy (ΔHm) of the related polymers were obtained by use of differential scanning calorimetry analysis. The results are: Tg = 103.4–104.5°C, Tm = 291.5–304.7°C, and ΔHm = 104.4–115.4 J/g. Thermal properties such as thermal decomposition temperature and decomposition kinetics were investigated by thermogravimetric analysis under nitrogen. The initial and maximum rate temperatures of degradation were found to be 401.5–411.7°C and 437–477°C, respectively. The parameters of thermal decomposition kinetics of PPSAs were worked out to be: activation energy of degradation was 135 to 148 kJ/mol and the 60-s half-life temperature was 360 to 371°C. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 66: 1227–1230, 1997  相似文献   

6.
Some wholly aromatic polyamides derived from unsubstituted and chloro- and nitro-substituted diamines have been studied from the viewpoint of their thermal stability, thermo-oxidative stability, and thermal transitions. General relationships between thermal stability of a polymer and its chemical structure are described. Decrease in thermal stability of poly(1,3-phenyleneisophthalamide) and poly(1,4-phenyleneterephthalamide) due to substituents has been explained and supported in part by infrared spectral data. The effect of electron-withdrawing substituents such as chloro and nitro in increasing the thermo-oxidative resistance of the polyamides is pointed out. The thermal transitions (Tg and Tm) of these polymers are also reported. All the polyamides exhibit a broad exothermic peak in the 630–700°C temperature range, which probably corresponds to reactions (crosslinking and cyclization) responsible for the high char yield of these systems.  相似文献   

7.
A novel diamine monomer having pendant 4‐(quinolin‐8‐yloxy) aniline group was successfully synthesized via aromatic substitution reaction of 8‐quinolinol with p‐fluoronitrobenzene followed by Pd/C catalyzed hydrazine reduction, amidation reaction between 4‐(quinolin‐8‐yloxy) aniline and 3,5‐dinitrobenzoylcholoride followed by Pd/C catalyzed hydrazine reduction. The diamine monomer was fully characterized by using FTIR, 1H‐NMR, 13C‐NMR, and elemental analysis. The diamine monomer was polymerized with various aromatic and aliphatic dicarboxylic acids to obtain the corresponding polyamides. The polyamides had inherent viscosity in the range of 0.30–0.41 dL/g and exhibited excellent solubility in the polar aprotic solvents such as DMAc, NMP, N,N‐dimethylformamide, Pyridine, and DMSO. The glass transition temperatures (Tg) of the polymers are high (up to 313°C) and the decomposition temperatures (Ti) range between 200 and 370°C, depending on the diacids residue in the polymers backbone. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010  相似文献   

8.
A series of new aromatic polyamides containing cinnamide pendent units were prepared from 2′‐(cinnamide)ethyl‐3,5‐diaminobenzoate and various aromatic dicarboxylic acids by the direct polycondensation reaction, with triphenyl phosphite and pyridine as condensing agents. The polyamides were characterized by 1H NMR, IR, and UV spectroscopy, and gel permeation chromatography. Their thermal stability was studied by thermogravimetric analysis in air, and differential scanning calorimetry. These polymers were readily soluble in polar aprotic solvents and can be cast from their solutions in flexible and tough films. Glass transition temperatures (Tgs) of these polyamides were observed in the range of 225–245°C. Their inherent viscosities varied from 0.77 to 1.12 dL/g that corresponded to weight–average and number–average molecular weights of 39,000–72,700 and 18,800–29,000, respectively. These polymers can be photochemically crosslinked. The photochemical aspects were revealed by means of UV–vis and IR analyses onto thin films. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 2013–2020, 2007  相似文献   

9.
A series of soy-based polyamides with different dimer acids and diamines were synthesized using a condensation polymerization technique. The molecular weight of polyamides prepared from 1,4-phenylenediamine increases greatly with a reaction temperature above 260°C. The physical properties of the polyamides, such as glass transition temperature (Tg), melting point (Tm), decomposition temperature (Td), crystalline behavior, and mechanical strength strongly depend on their molecular weight and flexibility of diamines used. The aromatic-based polyamides have a higher Tg, Tm, Td, and stronger mechanical strength than that of aliphatic-based polyamides. X-ray diffraction patterns of the samples indicate that all of the resins synthesized present a typical semicrystalline morphology. Polyamides made from hydrogenated dimer acid possess lower Tg and higher mechanical strength, compared with polyamides from unsaturated dimer acid with different dimer and trimer ratios. These results are analyzed and discussed in accordance with the influence of rigid aromatic segments and the microstructure of different dimer acids. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 68:305–314, 1998  相似文献   

10.
Several new polyamides were synthesized by direct polycondensation of the 1,3-bis[4-(4-aminophenoxy)phenyl]adamantane ( I ) with various dicarboxylic acids. The polyamides had inherent viscosities and number-average molecular weights (Mn) of 0.46–0.96 dL/g and 28,000–109,000, respectively. All polyamides III had good solubilities and were soluble in N-methyl-2-pyrrolidone (NMP), N,N-dimethylacetamide (DMAc), N,N-dimethylformamide (DMF), and pyridine. Polyamides had tensile strengths of up to 72.3 MPa, elongation to breakage values of up to 10.2%, and initial modulus of up to 2.1 GPa. Their glass transition temperatures were found to be 228–269°C and 252–307°C using differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA), respectively. The melting temperature of IIIf was observed at 318°C using DSC. The temperatures of polyamides III at a 5% weight loss ranged from 395 to 435°C in air and from 400 to 450°C in a N2 atmosphere. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 68:315–321, 1998  相似文献   

11.
A series of processable semi-aromatic polyamides containing thioether and methylene units were synthesized through the reaction of 4,4-thiobis(methylene)dibenzoyl chloride and aliphatic diamine by the method of interfacial polycondensation. These polyamides had excellent thermal properties with glass transition temperatures (T g) of 104.3–130.6 °C, melting temperatures (T m) of 300.3–303.8 °C, and initial degradation temperatures (T d) of 405.2–410.3 °C. They had wider processing windows than traditional semi-aromatic polyamides (such as PA6T can not be processed by melting) and can be processed by melting method. They had better tensile strengths of 57.6–64.1 MPa, low-temperature mechanical properties, low water absorption of 0.19–0.27 %, low dielectric constants of 3.11–3.95 at 100 kHz, and better melt flowability properties of 232–60.7, 301.9–78.8, and 423.1–83.6 Pa s under a shear rate ranging from 20 to 1,170 s?1, respectively. In addition, these polyamides showed good corrosion resistance, they did not dissolve in solvents such as NMP, DMSO, hydrochloric acid (6 mol/l), and solution of NaOH (1 mol/l) and so on.  相似文献   

12.
A series of bismaleimides (BMI) and bisnadimides (BNI) containing pyridine ring and flexible linkages were prepared and the structural characterization of the resins was carried out by elemental analysis, FTIR, 1H NMR, and 13C NMR spectroscopy. Their curing behavior were characterized by differential scanning calorimetry and thermal stability of the cured resins were investigated by thermogravimetric analysis. In addition, a series of polyaspartimides were prepared by the polyaddition of the bismalemide with various dimaines. The polymers were characterized by FT‐IR, inherent viscosity, and molecular weight measurements. All the polyimides were soluble in many organic solvents, the glass transition temperature of the polyaspartimides are in the range of 194–231°C, 10% weight loss (T10) takes place in the temperature range of 379–482°C in N2 and char yield in the range of 44.31–53.31%. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008  相似文献   

13.
Infrared bands in the 900–1100 cm?1 region are sensitive to thermal energy. These bands can result from intermolecular coupling, producing the crystal lattice, or from intramolecular coupling of the various atomic groups in a regular helix or coiled chain. In either case an increase in temperature will disrupt the coupling mode, resulting in a form of structural relaxation and a reduction in the integrated absorbance. It is proposed that the temperature at which the peak areas begin to decrease be assigned as the Tg. This is measured by continuously scanning a selected peak in the infrared spectrum of a polymer film while it is heated at a rate of about 1°C/min. Using this technique polyamides (nos. 6,66, and 610) exhibited transitions in the 30–50°C range, and by studying the increase in the free NH region (3440 cm?1) of nylon 66 two other transitions were detected at 80 and 137°C; the latter represents a change in the nylon 66 crystal state. An amorphous film of poly(ethylene terephthalate) displayed a transition at 58–68°C (Tg) and at 85°C, which is the crystallization temperature. Films of poly(vinyl acetate) and polystyrene exhibited transitions at 25–37°C and at 70°C, respectively.  相似文献   

14.
A number of polyamides based on 2,6-naphthalene dicarboxylic acid (NDA) and various aromatic diamines were synthesized in N-methyl pyrrolidone (NMP) containing lithium chloride (LiCl) or calcium chloride (CaCl2) by direct polycondensation using triphenyl phosphite and pyridine. The best reaction conditions for polycondensation were determined in terms of factors such as the amount of the solvency-promoting reagent such as LiCl or CaCl2 and the initial reactant concentration. Thus, almost all polyamides were obtained with inherent viscosities above 1.0 and up to 3.28 dL/g. Similarly, high molecular weight copolyamides with inherent viscosities of 1.76–3.61 dL/g were prepared from 4,4′-oxydianiline (ODA) and mixed dicarboxylic acids of NDA/terephthalic acid (TPA) or NDA/isophthalic acid (IPA). The solubility of NDA homopolyamides depended on the diamine components. The polyamides derived from meta-, sulfone-, or alkylene-linked diamine showed increased solubility. Copolymerization of ODA with NDA/IPA led to a significant increase in solubility, whereas with NDA/TPA, it gave a limited improvement. All the homopolyamides and copolyamides showed an amorphous X-ray diffraction pattern. Almost all the polymers soluble in aprotic solvents can be solution-cast into strong and tough films. Glass transition shifts of some NDA polyamides can be observed in the differential scanning calorimetry (DSC) curves ranging from 243 to 345°C. Most NDA/IPA–ODA copolyamides also showed clear transitions in the range of 255–268°C. In nitrogen, all the polymers showed no significant weight loss up to 400°C, and their 10% weight loss temperatures were recorded in the range of 434–541°C. © 1994 John Wiley & Sons, Inc.  相似文献   

15.
The effect of thermal treatment over a wide range of temperature (130–280°C) on the crystallization behavior of nylon 6 was studied by using DSC, FTIR, and polarized light microscope equipped with a hot stage. The crystallization and the subsequent melting behavior of the nylon 6 samples treated at different temperatures (Ts) were classified into four types. When Ts was higher than 236°C or lower than 213°C, the crystallization behavior of nylon 6 was insensitive to the variation of Ts. When Ts was in the range of 213–235°C, the crystallization behavior was sensitive to the change of Ts. The polarized light microscopic experiments have demonstrated that a large amount of tiny ordered nylon 6 segments/cluster persisted when nylon 6 film are heated to 231°C. Consequently, the fastest crystallization speed was observed. As Ts was between 214 and 223°C, both the Tm and the ΔHm were higher than those of the nylon 6 samples treated at other temperature. The polarized light microscopic investigations have also demonstrated that molten nylon 6 crystallizes by using the un‐molten nylon 6 crystals as nucleation center at 220°C. Crystallization at higher temperature produces nylon 6 with thicker crystalline lamella. The above results are helpful for rational design of thermal treatment procedure to obtain nylon 6 with different crystalline features. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42413.  相似文献   

16.
Amylopectin (AP), a potato‐starch‐based polymer with a molecular weight of 6,000,000 g/mol, was blended with poly(ε‐caprolactone) (PCL) and characterized with inverse gas chromatography (IGC), differential scanning calorimetry (DSC), and X‐ray diffraction (XRD). Five different compositions of AP–PCL blends ranging from 0 to 100% AP were studied over a wide range of temperatures (80–260°C). Nineteen solutes (solvents) were injected onto five chromatographic columns containing the AP–PCL blends. These solutes probed the dispersive, dipole–dipole, and hydrogen‐bonding interactions, acid–base characteristics, wettability, and water uptake of the AP–PCL blends. Retention diagrams of these solutes in a temperature range of 80–260°C revealed two zones: crystalline and amorphous. The glass‐transition temperature (Tg) and melting temperature (Tm) of the blends were measured with these zones. The two zones were used to calculate the degree of crystallinity of pure AP and its blends below Tm, which ranged from 85% at 104°C to 0% at Tm. IGC complemented the DSC method for obtaining the Tg and Tm values of the pure AP and AP–PCL blends. These values were unexpectedly elevated for the blends over that of pure AP and ranged from 105 to 152°C for Tg and from 166 to 210°C for Tm. The Tm values agreed well with the XRD analysis data. This elevation in the Tg and Tm values may have been due to the change in the heat capacity at Tg and the dependence of Tg on various variables, including the molecular weight and the blend composition. Polymer blend/solvent interaction parameters were measured with a variety of solutes over a wide range of temperatures and determined the solubility of the blends in the solutes. We were also able to determine the blend compatibility over a wide range of temperatures and weight fractions. The polymer–polymer interaction coefficient and interaction energy parameter agreed well on the partial miscibility of the two polymers. The dispersive component of the surface energy of the AP–PCL blends was measured with alkanes and ranged from 16.09 mJ/m2 for pure AP to 38.26 mJ/m2 when AP was mixed with PCL in a 50/50% ratio. This revealed an increase in the surface energy of AP when PCL was added. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 3076–3089, 2006  相似文献   

17.
A new copper‐containing Schiff‐base diamine, benzil bis(thiosemicarbazonato)copper(II) (CuLH4), was synthesized in two steps from benzil bisthiosemicarbazone (LH6). The ligand LH6 and the complex CuLH4 were characterized with Fourier transform infrared spectroscopy, 1H‐NMR, and elemental analysis. CuLH4 was used to prepare novel polyamides. The low‐temperature solution polycondensation of the complex CuLH4 with various aromatic and aliphatic diacid chlorides afforded copper‐containing Schiff‐base polyamides with inherent viscosities of 0.25–0.36 dL/g in N,N‐dimethylformamide (DMF) and 0.75 dL/g in H2SO4 at 25°C. The polyamides were generally soluble in a wide range of solvents, such as DMF, N,N‐dimethylacetamide, tetrahydrofuran, dimethyl sulfoxide, ethyl acetate, tetrachloroethane, hexamethylene phosphoramide, N‐methylpyrrolidone, and pyridine. Thermal analysis showed that these polyamides were practically amorphous, decomposed above 270°C, and exhibited 50% weight loss at and above 400°C. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008  相似文献   

18.
The thermal degradations of methyl methacrylate‐graft‐natural rubber (MG) at different heating rates (B) in nitrogen were studied by thermogravimetric analysis. The results indicate that the thermal degradation of MG in nitrogen is a one‐step reaction. The degradation temperatures increase along with the increment of heating rates. The temperature of initial degradation (T0) is 0.448B + 362.4°C, the temperature at maximum degradation rate, that is, the peak temperature on a differential thermogravimetric curve (Tp) is 0.545B + 380.7°C, and the temperature of final degradation (Tf) is 0.476B + 409.4°C. The degradation rate at Tp is not affected by B, and its average value is 48.9%; the degradation rate at Tf is not affected by B either, and its average value is 99.3%. The reaction order (n) is 2.1 and is not affected by B. The reaction activation energy (E) and the frequency factor (A) increase along with B, and the apparent reaction activation energy (E0) is 254.6 kJ/mol. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 2952–2955, 2002  相似文献   

19.
Poly(ether ether sulfone) (PEES) containing semi‐aromatic polyamides with methylene units and ether linkage were synthesized through the copolymerization of m‐dihydroxybenzene, 4,4‐dichlorodiphenylsulfone (DCDPS) and 1,6‐N, N′‐bis(4‐fluorobenzamide) hexane (BFBH) by the method of nucleophilic polymerization. The inherent viscosities of the resultant different proportion of copolymers were in the range of 0.39–0.78 dL/g. These copolymers were found to have excellent thermal properties with glass transition temperatures (Tg) of 121–177°C, and initial degradation temperatures (Td) of 417.5–432.5°C. These copolymers showed good mechanical properties with tensile strengths of 45–83 MPa, storage modulus of 1.8–2.6 GPa. The complex viscosities of pure Poly(ether ether sulfone) (PEES) was in the range of 176,000–309.8 Pas from 0.01 to 100 Hz, the complex viscosities of the copolymers decreased significantly with the increase of semi‐aromatic amide content, the copolymers of 20% decreased from 4371 to 142.4 Pas (from 0.01 to 100 Hz), and the copolymers of 70% dropped from 634.6 Pas to 55.97 Pas (from 0.01 Hz to 100 Hz). All copolymers exhibited non‐Newtonian and shear‐thinning behavior. These results suggested the resultant copolymers possess better melt flowability that is beneficial for the materials’ melt processing. POLYM. ENG. SCI., 56:44–50, 2016. © 2015 Society of Plastics Engineers  相似文献   

20.
Interfacial polymerization is used to prepare biobased furan polyamides from the carbohydrate‐derived monomer, 2,5‐furan dicarboxylic acid, aromatic diamines, and varying chain length aliphatic diamines. The molecular weights of the furan polyamides variations range 10,000–70,000 g/mol. These biobased polyamides have improved solubility relative to petroleum‐derived polyamides affording enhanced processability options. The glass transition temperatures (Tg) of the biobased furan polyamides are higher than that of aliphatic analogs, but lower than phenyl‐aromatic analogs. The Tg for these furan polyamides are as high as 280 °C. Also, the furan polyamide glass transition temperatures increase with decreasing aliphatic diamine chain length similar to results exemplified in petroleum‐based nylons. Group contribution parameters are determined for furans to enable simple prediction of the glass transition temperature and decomposition temperature of furan polyamides. The molar glass transition function for the furan is calculated to be 27.6 ± 1.5 K kg/mol. Thermal analysis measurements of the biobased furan polyamides have maximum thermal degradation temperatures at 350 °C or higher, similar to that of aliphatic polyamides when scaled with the number average molecular weight. The molar decomposition temperature functions are determined to be 37 K kg/mol for furans bonded to aliphatic units and 42 K kg/mol for furans bonded to phenyl units. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45514.  相似文献   

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