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1.
In this article, a novel boron‐doped silicone resin (BSR) was synthesized by hydrolysis‐polycondensation method, with propyl‐triethoxysilane (PTES), dimethyl‐diethoxysilane (DMDES), and boric acid (BA) as starting materials, using absolute ethyl alcohol as solvent and hydrochloric acid as catalyst. The structures of the BSR were characterized by Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR), Xray photoelectron spectroscopy (XPS), and gel permeation chromatography (GPC). FTIR spectra showed characteristic B? O? Si and Si? O? Si stretching modes. XPS and NMR results confirmed further that boron element was doped successfully into the main chains of the silicone resin as Si? O? B bond motifs, and hydroxyl groups from BA were condensed properly with Si? OH or Si? OR to form cross‐linked structure of BSR with narrowed molecular weight distributions in optimum experimental condition. The thermal stability of the BSR was studied by thermogravimetry analysis and derivative thermogravimetry. The thermal degradation temperature of the silicone resin improved greatly after doping element boron into the main chain, and the thermal stability of the BSR was influenced by the content of boron. The thermal degradation mechanism of this BSR was also discussed. The degradation process can be divided into two stages, the weight loss in the first stages may be corresponding to the loss of the small groups and weaker bonds in the chains, such as ? CH3, and ? C3H7, the weight loss in the second stage may be corresponding to the loss of the group as ? OC2H5. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40934.  相似文献   

2.
Nanocomposites based on biodegradable poly(butylene succinate) (PBS) and layered silicates were prepared by melt intercalation. Nonmodified montmorillonite (MMT) and MMTs (DA‐M, ODA‐M, ALA‐M, LEA‐M, and HEA‐M) organo‐modified by protonated ammonium cations {i.e., those of dodecylamine, octadecylamine, 12‐aminolauric acid, N‐lauryldiethanolamine, and 1‐[N,N‐bis(2‐hydroxyethyl)amino]‐2‐propanol, respectively} were used as layered silicates. From morphological studies using transmission electron microscopy, DA‐M, ODA‐M, and LEA‐M were found to be dispersed homogeneously in the matrix polymer, whereas some clusters or agglomerated particles were observed for ALA‐M, HEA‐M, and MMT. The enlargement of the difference in the interlayer spacing between the clay and PBS/clay composite, as measured by X‐ray diffraction, had a good correlation with the improvement of the clay dispersion and with the increase in the tensile modulus and the decrease in the tensile strength of the PBS composites with an inorganic concentration of 3 wt %. Dynamic viscoelastic measurements of the PBS/LEA‐M nanocomposite revealed that the storage modulus and glass‐transition temperature increased with the inorganic concentration (3–10 wt %). © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 1463–1475, 2004  相似文献   

3.
EVA copolymer/organoclay nanocomposites were prepared using melt‐compounding. Organoclays were obtained using wet and semi‐wet modification methods. These methods enable us to obtain organoclays with adequate modifier incorporation, but organoclays with a homogeneous and narrow agglomeration size distribution were obtained only with the wet method. TS and EB were higher for nanocomposites obtained with organoclays prepared using the wet method. Analysis of Limiting Oxygen Index, UL94 test and Cone Calorimeter test showed that the retardant properties of nanocomposites were also influenced by the kind of modifiers and the modification method.

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4.
Phenolic resin/poly(dimethylsiloxane adipamide) (PDMSA) blends, which have been prepared, show miscibility due to intermolecular H‐bonding existing between phenolic resin and the PDMSA. The specific H‐bonding of novolac type phenolic/PDMSA blends was characterized by means of glass transition temperature behavior and Fourier Transform Infrared Spectroscopy (FTIR). The strength of intermolecular H‐bonding within the phenolic blend is a function of the H‐bonded group of the PDMSA modifier and corresponds to the deviation glass transition temperature (ΔTg). Phenolic/PDMSA blends were completely miscible, as confirmed by the Tg study. The FTIR result is in good agreement with the inference from Tg behavior. The char yield of phenolic/PDMSA corresponds to the phenolic resin content. The molecular mobility of phenolic/PDMSA blends increases with PDMSA content in the phenolic‐rich region. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 984–992, 2002  相似文献   

5.
2,7‐Bis(4‐aminophenoxy) naphthalene (BAPN), a naphthalene‐containing diamine, was synthesized and polymerized with a 3,3′,4,4′‐benzophenone tetracarboxylic dianhydride (BTDA) to obtain a polyimide (PI) via thermal imidization. To enhance the thermal and mechanical properties of the polymer, PI–Montmorillonite (MMT) nanocomposites were prepared from a DMAc solution of poly(amic acid) and a DMAc dispersion of MMT, which were organo‐modified with various amounts of n‐dodecylamine (DOA) or cetylpyridium chloride (CPC). FTIR, XRD, and TEM (transmission electron microscopy) were used to verify the incorporation of the modifying agents into the clay structure and the intercalation of the organoclay into the PI matrix. Results demonstrated that the introduction of a small amount of MMT (up to 5%) led to the improvement in thermal stability and mechanical properties of PI. The decomposition temperature of 5% weight loss (Td,5%) in N2 was increased by 46 and 36°C in comparison with pristine PI for the organoclay content of 5% with DOA and CPC, respectively. The nanocomposites were simultaneously strengthened and toughened. The dielectric constant, CTE, and water absorption were decreased. However, at higher organoclay contents (5–10%), these properties were reduced because the organoclay was poorly dispersed and resulted in aggregate formation. The effects of different organo‐modifiers on the properties of PI–MMT nanocomposite were also studied; the results showed that DOA was comparable with CPC. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci, 2006  相似文献   

6.
A novel phosphorus‐containing dicyclopentadiene novolac (DCPD‐DOPO) curing agent for epoxy resins, was prepared from 9,10‐dihydro‐oxa‐10‐phosphaphenanthrene‐10‐oxide (DOPO) and n‐butylated dicyclopentadiene phenolic resin (DCPD‐E). The chemical structure of the obtained DCPD‐DOPO was characterized with FTIR, 1H NMR and 31P NMR, and its molecular weight was determined by gel permeation chromatography. The flame retardancy and thermal properties of diglycidyl ether bisphenol A (DGEBA) epoxy resin cured with DCPD‐DOPO or the mixture of DCPD‐DOPO and bisphenol A‐formaldehyde Novolac resin 720 (NPEH720) were studied by limiting oxygen index (LOI), UL 94 vertical test and cone calorimeter (CCT), and differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA), respectively. It is found that the DCPD‐DOPO cured epoxy resin possess a LOI value of 31.6% and achieves the UL 94 V‐0 rating, while its glass transition temperature (Tg) is a bit lower (133 °C). The Tg of epoxy resin cured by the mixture of DCPD‐DOPO and NPEH720 increases to 137 °C or above, and the UL 94 V‐0 rating can still be maintained although the LOI decreases slightly. The CCT test results demonstrated that the peak heat release rate and total heat release of the epoxy resin cured by the mixture of DCPD‐DOPO and NPEH720 decrease significantly compared with the values of the epoxy resin cured by NPEH720. Moreover, the curing reaction kinetics of the epoxy resin cured by DCPD‐DOPO, NPEH720 or their mixture was studied by DSC. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44599.  相似文献   

7.
Copolymers (p-CMF) synthesized by the condensation of p-cresol and melamine with formaldehyde in the presence of an acid catalyst and using varied molar proportion of the reacting monomers. Copolymer resin compositions were determined on the basis of their elemental analysis. The number average molecular weight of these copolymers was determined by conductometric titration in nonaqueous media. Solution viscosity measurements in dimethyl sulfoxide (DMSO) were carried out to ascertain the characteristic functions and constants of the copolymer resins. The copolymer resins were further characterized byUV–visible absorption spectra in the nonaqueous medium, Infra-red (IR) spectra, and the nuclear magnetic resonance (NMR) spectra. Thermal studies of the resins were carried out to determine their mode of decomposition, the activation energy (Ea), order of reaction (n), frequency factor (Z), entropy change (ΔS), free energy change (ΔF), and apparent entropy change (S*). Thermal decomposition curves were discussed with careful attention of minute details. The Freeman-Carroll and Sharp-Wentworth methods have been used to calculate thermal activation energy and thermal stability. Thermal activation energy (Ea) calculated with these methods are in agreement with each other. The data from the Freeman-Carroll methods have been used to determine various thermodynamic parameters. The order of thermal stability of copolymers has been determined using TGA. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008  相似文献   

8.
Polymer nanocomposites based on poly (ethylene 2,6‐naphthalate) (PEN) and carbon nanotubes (CNTs) were prepared by direct melt blending with a twin‐screw extruder. Dynamic thermogravimetric analysis was conducted on the PEN/CNT nanocomposites to clarify the effect of CNTs on the thermal decomposition behavior of the polymer nanocomposites. The thermal decomposition kinetics of the PEN/CNT nanocomposites was strongly dependent on the CNT content, the heating rate, and the gas atmosphere. On the basis of the thermal decomposition kinetic analysis, the variation of the activation energy for thermal decomposition revealed that a very small quantity of CNTs substantially improved the thermal stability and thermal decomposition of the PEN/CNT nanocomposites. Morphological observations demonstrated the formation of interconnected or network‐like structures of CNTs in the PEN matrix. The unique character of the CNTs introduced into the PEN matrix, such as the physical barrier effect of CNTs during thermal decomposition and the formation of interconnected or network‐like structures of CNTs, resulted in the enhancement of the thermal stability of the PEN/CNT nanocomposites. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009  相似文献   

9.
Liquefaction of southern pine wood in phenol in 30–40 : 70–60 weight ratios resulted in homogeneous liquefied materials, which were directly used to synthesize phenol–formaldehyde (PF)‐type resins. The synthesized resins showed good physical and handling properties: low viscosity, stability for storage and transportation, and resin applicable by a common sprayer. Particleboard panels bonded with the synthesized resins showed promising physical properties and significantly lower formaldehyde emission values than those bonded with the urea–formaldehyde resin control. One deficiency observed for the synthesized resins was lower internal bond values, which might be overcome the use of a hot‐stacking procedure. Overall, the process of wood liquefaction with limited amounts of phenol as a solvent was shown to have the potential of providing practical, low‐cost PF‐type resins with very low formaldehyde emission potentials. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009  相似文献   

10.
We present a novel approach to improving organoclay exfoliation in a nonpolar matrix, polyethylene. High‐density polyethylene (HDPE) particles were modified by exposure to a reactive gas atmosphere containing F2 and O2. This treatment was aimed at increasing the polarity of the polymer with the formation of carboxyl, hydroxy, and ketone functionalities on the particle surface. The surface‐treated high‐density polyethylene (ST‐HDPE) particles were then melt‐mixed with an appropriate organoclay to form nanocomposites. Transmission electron microscopy (TEM), wide‐angle X‐ray scattering, stress–strain analysis, and Izod impact measurements were used to evaluate the nanocomposite morphology and physical properties. These data were compared to those of equivalent nanocomposites prepared from unmodified HDPE and high‐density polyethylene grafted with maleic anhydride (HDPE‐g‐MA). The nanocomposites prepared from the ST‐HDPE particles exhibited much better properties and organoclay dispersion than those prepared from unmodified HDPE. The level of reinforcement observed in ST‐HDPE‐based nanocomposites was comparable to, if not better than, that seen in HDPE‐g‐MA‐based nanocomposites. However, a comparison of the TEM micrographs suggested better organoclay exfoliation in HDPE‐g‐MA than the current version of ST‐HDPE. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 2980–2989, 2006  相似文献   

11.
Polypropylene (PP)/montmorillonite (MMT) nanocomposites were prepared by compounding maleic anhydride‐g‐polypropylene (MAPP) with MMT modified with α,ω‐diaminododecane. Structural characterization confirmed the formation of characteristic amide linkages and the intercalation of MAPP between the silicate layers. In particular, X‐ray diffraction patterns of the modified clay and MAPP/MMT composites showed 001 basal spacing enlargement as much as 1.49 nm. Thermogravimetric analysis revealed that the thermal decomposition of the composite took place at a slightly higher temperature than that of MAPP. The heat of fusion of the MAPP phase decreased, indicating that the crystallization of MAPP was suppressed by the clay layers. PP/MAPP/MMT composites showed a 20–35% higher tensile modulus and tensile strength compared to those corresponding to PP/MAPP. However, the elongation at break decreased drastically, even when the content of MMT was as low as 1.25–5 wt %. The relatively short chain length and loop structure of MAPP bound to the clay layers made the penetration of MAPP molecules into the PP homopolymer phase implausible and is thought to be responsible for the decreased elongation at break. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 95: 307–311, 2005  相似文献   

12.
New nanocomposites based on a vinylester resin (VER) and the organo‐montmorillonites (ODA‐M, BHL‐M, DEM‐M, BHLV‐M) modified with octadecylammonium, bis(2‐hydroxyethyl)lauryl ammonium, diethyl[2‐(methacryloyloxyl)ethyl]ammonium, and bis(2‐hydroxyethyl)lauryl(vinylbenzyl)‐ammonium chlorides, respectively, were prepared by dispersing the organoclays in VER, and subsequent crosslinking at finally 120°C. X‐ray diffraction studies and morphological studies using transmission electron microscopy revealed that exfoliation occurs for the VER/ODA‐M and BHL‐M composites, intercalation occurs for the VER/BHLV‐M composite, and neither intercalation nor exfoliation occur for the VER/DEM‐M and unmodified montmorillonite composites. On the whole, although the enhancement in flexural modulus was observed for the exfoliated ODA‐M and BHL‐M composites, the flexural strength was rather lowered. Dynamic viscoelastic measurement revealed that the ODA‐M, BHL‐M, and BHLV‐M nanocomposites have significantly higher storage modulus at the rubbery state than the other composites. Polym. Eng. Sci. 44:2041–2046, 2004. © 2004 Society of Plastics Engineers.  相似文献   

13.
The thermal degradation of acrylonitrile‐butadiene‐styrene (ABS) added ammonia polyphosphate (APP) or APP/montmorillonite (MMT) nanocomposite was studied. The whole degradation progress of ABS could be regarded as the combination of the thermal degradation of polystyrene (PS) and polybutadiene (PB). The PB influences the formation of char while PS influences the maximum mass loss rate and its decomposition temperature. APP or APP/MMT nanocomposite could decrease the maximum mass loss rate and promotes the formation of char. A SiO2 network was formed on the char surface of the ABS‐APP/MMT composite which could improve the strength of the char and flame retardancy of ABS. It was found that when APP/MMT mixture or APP/MMT nanocomposite are added to ABS, NH3 (the gas product of APP) was buried in the residue and released until full degradation of ABS. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40704.  相似文献   

14.
Summary: Vinylester resin matrix composites were fabricated with 1, 3, 5 and 10 wt.‐% loadings of organoclay. The composite samples were subjected to various characterization techniques like X‐ray diffraction, flexural testing, dynamic mechanical analysis, thermogravimetric analysis, and scanning electron microscopy. The clay samples as well as the clay–resin composites were investigated by X‐ray diffraction. From the shift in the peak positions and the change in d‐spacing values, it was evident that there was intercalation in the 10 wt.‐% composites, whereas exfoliation occurred in the 1, 3, and 5 wt.‐% composites. The flexural strength and the breaking energy of all the composites were decreased compared with the unfilled resin, but there was an increase in flexural modulus value by 13%. From the dynamic mechanical analysis of the 3 and the 5 wt.‐% composites, it was observed that the loss modulus value was higher in the 3 wt.‐% composites, but the glass transition temperature was slightly higher in the 5 wt.‐% composites. Thermal degradation behavior was also improved in the 5 wt.‐% composites compared with the 3 wt.‐% composites.

Fracture surface of 3 wt.‐% clay filled vinylester resin matrix composite in different magnifications.  相似文献   


15.
Three kinds of 2‐ethyl‐4‐methylimidazole (EMI) derivatives (N‐acetyl EMI, N‐benzoyl EMI, and N‐benzenesulfonyl EMI) were synthesized through the reaction of EMI with acetyl chloride, benzoyl chloride, and benzenesulfonyl chloride, respectively. And the structure was confirmed by Fourier transform infrared spectroscopy (FTIR) and 1H‐nuclear magnetic resonance spectroscopy (1H NMR) spectra. Furthermore, the synthesized EMI derivatives were applied in diglycidyl ether of bisphenol A epoxy resin (DGEBA) as latent curing agent. Differential scanning calorimeter (DSC) was used to analyze the curing behavior of DGEBA/EMI derivative systems, indicating DGEBA could be efficiently cured by the EMI derivatives at 110~160°C, and the corresponding curing activation energy ranged from 71 to 86 kJ/mol. Viscosity data proves that the storage life of DGEBA with N‐acetyl EMI (NAEMI), N‐benzoyl EMI (NBEMI), and N‐benzenesulfonyl EMI (NBSEMI) at room temperature was 38 d, 50 d, and 80 d, and that at 10°C was 90 d, 115 d, and 170 d, respectively. Besides, thermogravimetry (TG), izod impact strength (IIS), and tensile shear strength (TSS) were tested to characterize the thermal stability and mechanical properties of DGEBA cured by EMI derivatives. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42563.  相似文献   

16.
A modified clay was used to prepare poly(L ‐lactic acid)/clay nanocomposite dispersions. X‐ray diffraction and transmission electron microscopy experiments revealed that poly(L ‐lactic acid) was able to intercalate the clay galleries. IR spectra of the poly(L ‐lactic acid)/clay nanocomposites showed the presence of interactions between the exfoliated clay platelets and the poly(L ‐lactic acid). Thermogravimetric analysis and differential scanning calorimetry were performed to study the thermal behavior of the prepared composites. The properties of the poly(L ‐lactic acid)/clay nanocomposites were also examined as functions of the organoclay content. The exfoliated organoclay layers acted as nucleating agents, and as the organoclay content increased, the crystallization temperature increased. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007  相似文献   

17.
Six blend samples were prepared by the physical mixing of epoxidized resole (EDR) with different weight ratios of carboxyl‐terminated polybutadiene (CTPB) liquid rubber ranging from 0 to 25 wt % in intervals of 5 wt %. The formation of various reaction products during the curing of unblended EDR and CTPB‐blended EDR were studied with Fourier transform infrared spectroscopy. The curing time at 100°C for the blend sample containing 15 wt % CTPB was the least among all of the blend samples. This blend sample, also, showed the highest initial degradation temperature, as obtained from thermogravimetric analysis thermograms, which indicated that it was the most thermally stable matrix system. The films of coatings based on the blend of EDR with 15 wt % CTPB offered the highest resistance toward different concentrations of acids and alkalis compared to the films having 5, 10, 20, and 25 wt % CTPB in the EDR/CTPB blends. Solvents showed almost the same behavior as acids and alkalis for these films except for hydrocarbon solvents such as mineral turpentine oil, toluene, and xylene. The resistance toward these solvents was poor and slightly inferior to those found with EDR unblended with CTPB. The tensile, flexural, and impact strengths of the molded specimens derived from the EDR/CTPB blends initially increased up to 15 wt % CTPB addition in the blend and then decreased, whereas the elongation at break remained constant for all blend compositions. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 1802–1808, 2006  相似文献   

18.
A dynamic heating rate mode of high‐resolution thermogravimetric analysis was used to study the thermal and thermal‐oxidative stability, as well as kinetics analyses, of a model liquid rubber‐modified epoxy resin, Ep/CTBN, made up of bisphenol A diglycidyl ether‐based epoxy and carboxyl‐terminated butadiene acrylonitrile rubber (CTBN). Results show that the thermal degradation of Ep/CTBN resin in nitrogen and air consists of two and three independent steps, respectively. Moreover, Ep/CTBN has a higher initial degradation temperature and higher activation energy than those of pure epoxy resin in both gases, indicating that the addition of CTBN to epoxy can improve the thermal and thermal‐oxidative stability of pristine epoxy resin. Kinetic parameters such as activation energy, reaction order, and preexponential factor of each degradation step of both Ep/CTBN and pure epoxy resins in air and nitrogen were calculated. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 3594–3600, 2003  相似文献   

19.
In this research the possibility to produce nanosilica/phenolic nanocomposites by means of a simple low labor cost mechanical approach was investigated. A commercial compatibilized nanosilica was selected as a filler and a resol diluted in methanol as a matrix. The morphology of the produced nanocomposites were studied by means of Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM), whereas thermogravimetric analysis (TGA) was used to study the thermal stability of the nanocomposites. The post burning morphology of samples was also investigated. A rheological characterization was also carried out. The results of such study showed that it was possible to obtain a good degree of dispersion and distribution of the nanosilica particles, indicating that the proposed process could be successfully adopted as an alternative approach to sol‐gel techniques. Thermogravimetric analyses showed that all the produced nanocomposites exhibited a better thermal stability than the pristine matrix. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011  相似文献   

20.
In this work, titanium nitride (TiN) nanoparticles were employed to achieve enhanced thermal insulation and flame retardance of phenolic foam (PF)/TiN nanocomposites (PFTNs) via in situ polymerization. The morphologies of PFTNs were observed by scanning electron microscope and the images showed that the PFTNs have more uniform cell morphologies compared with pure PF. Thermal insulating properties of PFTNs were evaluated by thermal conductivity tests. The introduction of TiN obviously decreased the thermal conductivities of PF over a wide temperature range (?20 to 60 °C). Significantly, the thermal conductivity of PFTNs gradually decreased as the temperature increased from 30 to 60 °C, showing a contrary tendency with that of pure PF. Moreover, the thermal stability and flame‐retardant properties of PFTNs were estimated by thermogravimetric analysis (TGA), UL‐94 vertical burning and limited oxygen index (LOI) tests, respectively. The TGA and LOI results indicated that PFTNs possess enhanced thermal stabilities and fire‐retardant performances with respect to the virgin PF. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43765.  相似文献   

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