首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 31 毫秒
1.
A novel tetra‐functional epoxy monomer with mesogenic groups was synthesized and characterized by 1H‐NMR and FTIR. The synthesized epoxy monomer was cured with aromatic amine to improve the thermal property of epoxy/amine cured system. The glass transition temperature (Tg) and coefficient of thermal expansion (CTE) of the cured system were investigated by dynamic mechanical analysis and thermal mechanical analysis. The properties of the cured system were compared with the conventional bisphenol‐A type epoxy and mesogenic type epoxy system. The storage modulus of the tetra‐functional mesogenic epoxy cured systems showed the value of 0.96 GPa at 250 °C, and Tg‐less behavior was clearly observed. The cured system also showed a low CTE at temperatures above 150 °C without incorporation of inorganic components. These phenomena were achieved by suppression of the thermal motion of network chains by introduction of both mesogenic groups and branched structure to increase the cross linking density. The temperature dependency of the tensile property and thermal conductivity of the cured system was also investigated. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46181.  相似文献   

2.
This article describes the synthesis and property evaluation of different hyperbranched polyurethane‐urea (HBPUU) coatings based on a newly synthesized triazole ring‐based pentol chain extender. For this initially, the chain extender was synthesized using acetylene azide click reaction and the structure of the intermediate compounds were confirmed by 1H‐, 13C‐NMR, FTIR, and ESI‐mass spectrometry. In the further steps, the required HBPUU coatings were prepared by a systematic three‐step reaction process. In the first step, a isocyanate terminated prepolymer resin was synthesized at NCO/OH ratio of 1.2 : 1, while the second and third step involves the partially chain extension followed by moisture curing. The excess NCO content in the prepolymer was calculated by standard dibutylamine titration method and partially (10, 20, 30, 50, and 70% of the excess NCO content) chain extended with the pentol chain extender and remaining was moisture cured. The structure property relation of different HBPUU coating films were analyzed by FTIR peak deconvulation technique using Gaussian curve fitting procedure while, their viscoelastic and thermo‐mechanical properties were measured by dynamic mechanical thermal analysis, thermo gravimetric analysis, differential scanning calorimetric, and universal testing machine instruments. These results showed that thermal stability, glass transition temperature (Tg), elongation at break increases but the storage and tensile modulus decreases with increasing the percent loading of the triazole chain extender. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012  相似文献   

3.
Novel phosphorus‐containing binaphthyl epoxy DGEBN (diglycidyl ether of 2,2′‐hydroxy‐1,1′‐binaphthalene) with high thermal performance was obtained from the addition reaction of DGEBN and diethyl phosphite. The modified binaphthyl epoxy was characterized by Fourier transform infrared (FTIR) and nuclear magnetic resonance spectroscopy. The dynamic mechanical property of the cured epoxy polymer was investigated by dynamic mechanical thermal analysis. The result revealed that the cured polymer with lower phosphorus content displayed higher value of the storage modulus when the networks reached rubbery state (above the glass transition temperature Tg). The Tgs decreased slightly with increasing phosphorous content. The thermal degradation was studied with thermogravimetric analysis and the evolved gas was analyzed using thermogravimetric analysis/Fourier transform infrared technique. The influence of phosphorus content and the chemical structure on the degradation behavior was discussed. The P‐modified binaphthyl epoxy polymers exhibited higher thermal stability than the P‐modified diglycidyl ether of bisphenol A polymer. Flammability measurements were performed by the examination of limited oxygen index and UL‐94 test. Compared with unmodified DGEBN, P‐containing epoxy polymers displayed higher limited oxygen index values and exhibited better flame retardance. POLYM. ENG. SCI., 2009. © 2009 Society of Plastics Engineers  相似文献   

4.
A novel acetylene‐ and maleimide‐terminated benzoxazine, 3‐(3‐ethynylphenyl)‐3,4‐dihydro‐2H‐6‐(N‐maleimido)‐1,3‐benzoxazine (MBZ‐apa), was successfully synthesized with N‐(4‐hydroxyphenyl)maleimide, paraformaldehyde, and 3‐aminophenylacetylene. The structure of the benzoxazine is confirmed by FTIR and 1H‐NMR spectroscopies. MBZ‐apa is easily dissolved in common organic solvents. Differential scanning calorimetry (DSC) was used to study thermal cross‐linking behavior of MBZ‐apa. The DSC curve shows only a single exothermic peak due to the oxazine ring‐opening polymerization and the polymerization of the acetylene and maleimide groups occurring simultaneously in the same temperature range. Dynamic mechanical analyses (DMA) reveals that the novel polybenzoxazine exhibits high glass‐transition temperature (Tg) (ca. 348°C). The storage modulus arrives at 4.5 GPa in the range of room temperature to 330°C. The polybenzoxazine exhibits good thermal stability as evidenced by thermogravimetric analysis (TGA). Pyrolysis‐gas chromatography/mass spectrometry (Pyrolysis‐GC/MS) was employed to characterize the polybenzoxazine. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013  相似文献   

5.
Novel thermosetting monomers possessing both maleimide and propargyl groups were first designed and synthesized. The monomers included N‐(2‐propargyloxyphenyl) maleimide (2‐PPM), N‐(3‐propargyloxyphenyl) maleimide (3‐PPM), and N‐(4‐propargyloxyphenyl) maleimide (4‐PPM), and their structures were confirmed with Fourier transform infrared (FTIR) spectroscopy, 1H‐NMR, and elemental analysis. The cure behaviors of these monomers were characterized with differential scanning calorimetry and FTIR spectroscopy, and the results indicated that the monomers had a broader processing window than normal bismaleimide (BMI) resins. The thermal properties of the cured monomers were characterized with thermogravimetric analysis and dynamic mechanical analysis. The 5% mass loss temperatures of the cured monomers were high (ca. 400°C), and the glass‐transition temperatures of cured 2‐PPM, 3‐PPM, and 4‐PPM were 386, 373, and 387°C, respectively, which were much higher than those of typical commercial blended BMI resins. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010  相似文献   

6.
A dimethacrylate based on bisphenol‐S (DBSMA) was prepared and characterized by Fourier Transform infrared spectroscopy (FTIR), Electrospray Ionisation Tandem Mass Spectrometry (ESI/MS) 1H NMR, and 13C NMR. DBSMA was investigated by a real‐time infrared spectroscopy (RTIR), under different conditions such as varying photoinitiator type and concentration, with and without oxygen, mixing with different amounts of a reactive diluent [1,6‐hexanediol dimethacrylate (HDDMA)]. The mechanical and thermal properties of these curing films were also investigated by dynamic mechanical analysis and thermogravimetric analysis. The results showed homopolymer of DBSMA has better thermal stability than copolymers of DBSMA/HDDMA systems. Also, the cured DBSMA polymer exhibited higher glass transition temperature (Tg) and better thermal stability compared with commercial available resin 2,2‐Bis[4‐(2‐hydroxy‐3‐methacryloxypropoxy)phenyl]propane (BIS‐GMA) (CN151). © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013  相似文献   

7.
A new bismaleimide monomer, 2‐((4‐maleimidophenoxy)methyl)‐5‐(4‐maleimidophenyl)‐1,3,4‐oxadiazole (Mioxd), was designed and synthesized. The chemical structure of the monomer was confirmed by means of Fourier transform infrared (FTIR) spectroscopy, proton nuclear magnetic resonance (1H NMR) spectroscopy and elemental analysis, and its thermal properties were characterized using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Mioxd as a reactive modifier was blended with epoxy resin based on bisphenol A diglycidyl ether (DGEBA) in weight ratio of 5, 10, and 15%, using 4,4′‐diaminodiphenyl sulfone (DDS) as hardener. The effect of Mioxd addition on the cure behavior and thermal properties of the blend resins was studied by DSC, TGA, and dynamic mechanical analysis (DMA). DSC investigations showed that the main exothermic peak temperature (Tp) of the blend systems did not obviously shift with increasing Mioxd content whereas a new shoulder appeared and gradually grew on the high temperature side of the exothermic peak. The results of DMA measurements exhibited the glassy storage modulus (G') and glass transition temperatures (Tg) increased as the Mioxd content was increased, the cured blends investigated were miscible and no phase separation occurred. Further, the thermal decomposition temperature first decreased and then increased, but the char yield at 600°C increased with an increase in Mioxd content. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers  相似文献   

8.
Random copolymers of 2,2‐dimethyltrimethylene carbonate and ethylene carbonate (EC) were synthesized with lanthanide tris(2,6‐di‐tert‐butyl‐4‐methylphenolate)s [Ln(DBMP)3; Ln = La, Nd, Sm, or Dy] as catalysts, among which La(DBMP)3 showed the highest activity. Poly(2,2‐dimethyltrimethylene carbonate‐co‐ethylene carbonate)s [poly(DTC‐co‐EC)]s with high molecular weights were prepared at room temperature and characterized with 1H‐NMR and size exclusion chromatography. The thermal behavior and crystalline properties of the poly(DTC‐co‐EC)s were analyzed with differential scanning calorimetry, thermogravimetric analysis, and X‐ray diffraction. The crystallinity and melting temperatures of the poly(DTC‐co‐EC)s both decreased with increasing EC content in the copolymers. The mechanical properties of these copolymers were also investigated with dynamic mechanical analysis and tensile strength measurements, which revealed that a reduction of the glass‐transition temperature and great enhancement of the tensile properties could be achieved with higher EC contents. These improvements in the thermal and mechanical properties indicate potential applications in biomedical research for novel polycarbonates. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010  相似文献   

9.
A novel engineering plastic polyundecamethylene 2,6‐naphthalamide (PA11N) was prepared via a reaction of 2,6‐naphthalene dicarboxylic acid and 1,11‐undecanediamine through a three‐step procedure. The structure of synthesized PA11N was characterized by elemental analysis, Fourier transform infrared spectroscopy, and proton nuclear magnetic resonance (1H‐NMR). The thermal behaviors were determined by differential scanning calorimetry, thermogravimetric analysis, and dynamic mechanical analysis. The solubility, water‐absorbing capacity, and mechanical properties of PA11N have also been investigated. Melting temperature (Tm), glass transition temperature (Tg), and decomposition temperature (Td) of PA11N are 294, 139, and 493°C, respectively. The results show that the heat resistance and mechanical properties of PA11N are near to those of polynonamethylene terephthalamide, and PA11N is a promising heat‐resistant and processable engineering plastic. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010  相似文献   

10.
Acrylate‐based epoxy resin (AE)/low molecular weight polyamine (LPA) composites were developed. The chemical structure, curing behavior, fracture morphology, damping properties, and mechanical properties were evaluated by Fourier transform infrared (FTIR), 1H‐nuclear magnetic resonance (1H‐NMR), gel permeation chromatography (GPC), Differential scanning calorimeter (DSC), scanning electron microscope (SEM), Dynamic mechanical thermal analysis (DMTA), and electro mechanical machine. Transmission electron microscope (TEM) and SEM pictures exhibited nanoscale micro‐phase separation between epoxy and acrylic segmers. DMTA results indicated that the loss factor of cured AE/LPA system could reach 1.84 and temperature range of tan δ > 0.5 was about 84 °C. Tensile strength and elongation at break of the cured AE samples can reach 6.5 MPa and 185%, respectively. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43654.  相似文献   

11.
A new reactive phosphorus‐containing curing agent with imine linkage called 4, 4′‐[1, 3‐phenyl‐bis(9, 10‐dihydro‐9‐oxa‐10‐phosphaphenanthrene‐10‐yl)dimethyneimino)]diphenol (2) was synthesized both via two‐pot and one‐pot procedure. The chemical structure of this curing agent was confirmed by FTIR, 1H, 13C, and 31P NMR spectra. A series of thermosetting systems were prepared by using conventional epoxy resins (E51), 4, 4′‐diaminodiphenyl methane (DDM) and (2). Resins with different phosphorus contents were obtained by changing the DDM/(2) molar ratios. Their dynamic mechanical thermal, thermal and flame‐retardant properties were evaluated by dynamic mechanical thermal analysis (DMTA), thermogravimetric analysis (TGA), and limiting oxygen index (LOI), respectively. All samples had a single Tg, which showed that these epoxy resins were homogeneous phase. Both the two char yields under nitrogen and air atmospheres increased with increasing content of (2) and the LOI values increased from 24.5 for standard resin to 37.5 for phosphorus‐containing resin, which indicated that incorporation of (2) could impart good thermal stability and excellent flame retardancy to the conventional epoxy thermosets. POLYM. ENG. SCI., 56:441–447, 2016. © 2016 Society of Plastics Engineers  相似文献   

12.
Star‐block copolymers comprised of poly(styrene) (S) core and four poly(ε‐caprolacton) (ε‐CL) arms were synthesized by the combination of free radical polymerization (FRP) of S and ring opening polymerization (ROP) of ε‐CL in one‐step in the presence of tetrafunctional ineferter. The block copolymers were characterized by 1H‐NMR and FTIR spectroscopy, gel permeation chromatography (GPC), and fractional precipitation method. 1H ‐NMR and FTIR spectroscopy and GPC studies of the obtained polymers indicate that star‐block copolymers easily formed as result of combination FRP and ROP in one‐step. The γ values (solvent/precipitant volume ratio) were observed between 1.04–2.72 (mL/mL) from fractional measurements. The results show that when the initial S feed increased, the molecular weights of the star‐block copolymers also increased and the polydispersities of the polymers decreased. Mw/Mn values of the products were measured between 1.4 and 2.86 from GPC. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010  相似文献   

13.
A thermotropic acetylene‐terminated liquid‐crystal monomer, 2‐methyl‐1,4‐phenylene bis(4‐ethynylbenzoate) (MPBE), was prepared and used as a modification composition to react and cocure with a silicon‐containing arylacetylene (PSA) oligomer for improving PSA resin. The curing behavior of the PSA–MPBE resins were characterized by differential scanning calorimetry and Fourier transform infrared spectroscopy. The microstructure and morphology of the PSA–MPBE resins were investigated by scanning electron microscopy (SEM) and transmission electron microscopy. Their dynamic mechanical properties and thermostability were measured by dynamic mechanical analysis (DMA) and thermogravimetric analysis. The results indicate that the thermotropic acetylene‐terminated liquid‐crystal monomer melted into a schlieren texture. MPBE and PSA could copolymerize to fix the mesogenic domain in the crosslinked network and form a homogeneous‐phase sea‐island structure, which improved the rigidity and toughness of the materials. DMA showed that the storage modulus of the PSA–MPBE resins increased by about 400 MPa compared to the those of the pure components. The SEM experiments showed a noticeable change in the morphology, from a typical brittle fracture for the pure PSA to microplastic deformation behavior for the PSA–MPBE resins. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45141.  相似文献   

14.
The effects of artificial and natural weathering tests on the structure and mechanical properties of polystyrene‐block‐polybutadiene‐block‐polystyrene (SBS) block copolymer were studied by spectrophotometry, Fourier Transform Infrared (FTIR) Spectroscopy, hardness measurements, and tensile testing. The correlation between artificial and natural weathering tests was also investigated. The results showed that the surface of SBS became yellow with increasing aging time. FTIR spectra confirmed the formation of carbonyl group in the aging process. The elongation at break, the tensile strength, and the tear strength decreased rapidly in the initial stage of the aging process and then leveled off, while the hardness increased with aging time. The correlation between artificial and natural weathering tests in Wanning and Hailaer, in China, could be expressed in terms of t1 = 2.50t01.99 and t2 = 1.92t02.56, respectively. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008.  相似文献   

15.
In this study, the mechanical and chemical properties of a series of sulfonated poly(styrene‐isobutylene‐styrene) (SIBS) block copolymers were evaluated using a combination of nanoindentation, dynamic mechanical analysis (DMA), elemental analysis (EA), Fourier transform infrared spectroscopy (FTIR), water absorption, and small angle X‐ray scattering studies (SAXS). The materials properties were characterized as a function of the sulfonation percent in the block copolymers, as well as a result of the counter‐ion substitution with Mg2+, Ca2+, and Ba2+. Nanoindentation studies revealed that the elastic modulus (E) and hardness (H) increase with sulfonation up to a certain level, at which point, the effect of water content further hinders any mechanical reinforcement. The incorporation of counter‐ions increases E and H, but the results are dependent upon the size of the counter‐ion. DMA results showed that the polymer maintained the glass transition temperature (Tg) of the polyisobutylene (PIB) segment (?60°C) regardless of the sulfonation level or counter‐ion substituted. However, both the shoulder of the PIB Tg (?30°C), which was probably caused by a Rouse‐type motion, as well as the Tg of polystyrene (105°C) disappeared upon sulfonation. Counter‐ion substitution increased the storage modulus of the rubbery plateau, which is indicative of a stronger and more thermally stable crosslinked complex formation. Additional unique relaxations were observed with the counter‐ions, and could be attributed to the stretching/rotation of the S? O bond and the interaction of the cations with the oxygen in the sulfonic group. FTIR results also revealed a unique shifting of the asymmetric S? O band when counter‐ions were added. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40344.  相似文献   

16.
Tunable biodegradable polyurethanes (PUs) with favorable mechanical properties were synthesized from 1,6‐hexamelthylene diisocyanate (HDI) as the hard segment, poly(?‐caprolactone) (PCL) as the soft segment, and L ‐cystine ester as chain extender. The structure of PUs was confirmed by FTIR and 1H‐NMR. The results of differential scanning calorimeter, thermogravimetric analysis, dynamic mechanical analysis, and tensile test revealed that the thermal and mechanical properties of PUs were strongly influenced by the molecular weight of soft segment PCL. In the presence of glutathione, the disulfide group cleaved into thiols, realizing the PUs degraded and the molecular weight decreased. For PU [550], it remained only 50% of the original Mw. Evaluation of cell viability demonstrated the nontoxicity of the PUs, which facilitated their potential in biomedical applications. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013  相似文献   

17.
Dispersion behavior of multiwalled carbon nanotube (MWCNT), rheological and mechanical properties of various MWCNT/poly(styrene‐co‐acrylonitrile) (SAN) nanocomposites were investigated. MWCNT/SAN nanocomposites were prepared by three different methods; MWCNT/SAN melt blending, MWCNT/SAN in situ atom transfer radical polymerization (ATRP) and functionalized‐MWCNT/SAN in situ ATRP. Formation of SAN onto the surface of MWCNT and the molecular weight of grafted‐SAN were confirmed by fourier transform infrared spectra, 1H‐NMR and 13C‐NMR. Crossover frequency of storage and loss modulus from rheological measurement and dynamic mechanical analysis showed that functionalized MWCNT/SAN in situ ATRP nanocomposite showed more uniform dispersion of MWCNT. Improved mechanical and electrical properties were observed for functionalized MWCNT/SAN in situ ATRP nanocomposite. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010  相似文献   

18.
Composites were prepared by solution blending poly(vinylidene fluoride) (PVDF) and multi‐walled carbon nanotubes (MWNTs). Fourier transform infrared spectroscopy (FTIR) and X‐ray diffraction (XRD) results showed that the crystalline structure of PVDF was changed by the addition of MWNTs and a MWNTs‐induced crystal transformation from α‐phase to β‐phase of PVDF was confirmed. With differential scanning calorimeter (DSC) and dynamic mechanic thermal analysis (DMA) techniques, thermal and mechanical properties of the composite films were examined. As the DSC results showed, addition of MWNTs would lead to the increased cooling crystallization temperature (Tc), implying that MWNTs nanoparticles could act as nucleating agents, which is further proved with the help of polarized optical microphotographs. On the other hand, the decreasing of Dd (degree of crystallinity) implied that the MWNTs networks can confine the crystallization of PVDF. Through the curve analysis of the dynamic mechanical measurements, it was found that the storage modulus (E′) is significantly enhanced, revealing that a strong interaction should exist between PVDF and MWNTs. POLYM. COMPOS., 2010. © 2009 Society of Plastics Engineers  相似文献   

19.
The bisphenol‐containing 4,4′‐biphenylene moiety was prepared by the reaction of 4,4′‐bis(methoxymethyl) biphenyl with phenol in the presence of p‐toluenesulfonic acid. The bisphenol was end‐capped with the cyanate moiety by reacting with cyanogen chloride and triethylamine in dichloromethane. Their structures were confirmed by Fourier transform infrared spectroscopy, 1H‐NMR, and elemental analysis. Thermal behaviors of cured resin were studied by differential scanning calorimetry, dynamic mechanical analysis, and TGA. The flame retardancy of cured resin was evaluated by limiting oxygen index (LOI) and vertical burning test (UL‐94 test). Because of the incorporation of rigid 4,4′‐biphenylene moiety, the cyanate ester (CE) resin shows good thermal stability (Tg is 256°C, the 5% degradation temperature is 442°C, and char yield at 800°C is 64.4%). The LOI value of the CE resin is 42.5, and the UL‐94 rating reaches V‐0. Moreover, the CE resin shows excellent dielectric property (dielectric constant, 2.94 at 1 GHz and loss dissipation factor, 0.0037 at 1 GHz) and water resistance (1.08% immersed at boiling water for 100 h). © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011  相似文献   

20.
In this article, 2,2′‐bis[4‐(4‐maleimidephen‐oxy)phenyl)]propane (BMPP) resin and N,N‐4,4′‐bismaleimidodiphenylmethyene (BDM) resin blends were modified by diallyl bisphenol A (DABPA). The effects of the mole concentration of BMPP on mechanical properties, fracture toughness, and heat resistance of the modified resins were investigated. Scanning electron microscopy was used to study the microstructure of the fractured modified resins. The introduction of BMPP resin improves the fracture toughness and impact strength of the cured resins, whose thermal stabilities are hardly affected. Dynamic mechanical analysis shows that the modified resins can maintain good mechanical properties at 270.0°C, and their glass transition temperatures (Tg) are above 280.0°C. When the mole ratio of BDM : BMPP is 2 : 1(Code 3), the cured resin performs excellent thermal stability and mechanical property. Its Tg is 298°C, and the Charpy impact strength is 20.46 KJ/m2. The plane strain critical stress intensity factor (KIC) is 1.21 MPa·m0.5 and the plane strain critical strain energy release rate (GIC) is 295.64 J/m2. Compared with that of BDM/DABPA system, the KIC and GIC values of Code 3 are improved by 34.07% and 68.10%, respectively, which show that the modified resin presented good fracture toughness. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40395.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号