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1.
In this work, 2‐(3‐p‐bromophenyl‐3‐methylcyclobutyl)‐2‐hydroxyethylmethacrylate (BPHEMA) [monomer] was synthesized by the addition of methacrylic acid to 1‐epoxyethyl‐3‐bromophenyl‐3‐methyl cyclobutane. The monomer and poly(BPHEMA) were characterized by FT‐IR and [1H] and [13C]NMR. Average molecular weight, glass transition temperature, solubility parameter, and density of the polymer were also determined. Thermal degradation of poly[BPHEMA] was studied by thermogravimetry (TG), FT‐IR. Programmed heating was carried out at 10 °C min−1 from room temperature to 500 °C. The partially degraded polymer was examined by FT‐IR spectroscopy. The degradation products were identified by using FT‐IR, [1H] and [13C]NMR and GC‐MS techniques. Depolymerization is the main reaction in thermal degradation of the polymer up to about 300 °C. Percentage of the monomer in CRF (Cold Ring Fraction) was estimated at 33% in the peak area of the GC curve. Intramolecular cyclization and cyclic anhydride type structures were observed at temperatures above 300 °C. The liquid products of the degradation, formation of anhydride ring structures and mechanism of degradation are discussed. © 1999 Society of Chemical Industry  相似文献   

2.
The effect of irradiation on the structure of epoxidized (50 %) natural rubber (ENR50) has been studied using Fourier transform infrared spectroscopy (FTIR). ENR50 was irradiated using a 3.0 MeV electron beam machine with doses ranging from 20 to 200 kGy. The influence of several additives such as trimethylolpropane triacrylate (TMPTA). Irganox®1010, and tribasic lead sulfate on the irradiation‐induced changes of ENR50 is investigated. Upon irradiation, ring opening of epoxide groups, and oxidation and crosslinking of residual double bonds occurred, leading to decreases in the intensities of epoxide and cis double bond bands and an increases in ether, furan and hydroxyl bands. Gel fraction and hardness values have been used to correlate changes in the structure of the rubber upon irradiation. The results show that the increase in gel fraction upon irradiation of pure ENR50 can be associated with irradiation‐induced crosslinking, ring opening side‐chain reactions of oxirane groups and oxidation at the cis‐double bonds. The addition of Irganox®1010 and tribasic lead sulfate inhibits irradiation‐induced reactions in ENR50 to a considerable extent. The importance of TMPTA in preventing intramolecular ring opening side‐chain reactions is also discussed. However, our studies do not reveal the exact nature of the irradiation‐induced reactions involved in ENR. © 2000 Society of Chemical Industry  相似文献   

3.
A palm oil‐based medium‐chain‐length polyhydroxyalkanoate (mcl‐PHA) was allowed to react with epoxidized natural rubber (ENR). There was no noticeable reaction at ambient temperature for short reaction times. However, after 30 min at 170°C, the mcl‐PHA underwent thermal degradation to generate carboxylic terminal groups that attacked the epoxy groups of the ENR. Evidence of the ring‐opening reaction was provided by both FTIR and 1H‐NMR. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010  相似文献   

4.
Radical copolymerization of behenyl (systematic IUPAC nomenclature: n‐docosyl) acrylate and behenyl fumarate has been carried out in toluene at 70°C using benzoyl peroxide as initiator. Gel permeation chromatography was used to determine molecular weights (MW) and molecular weight distribution (MWD) of behenyl acrylate–behenyl fumarate (BA‐BF) copolymers. 1H NMR and carbon analysis was used to determine the composition of BA‐BF copolymers. Monomer reactivity ratios for high conversion polymerization were calculated by conversion‐extended Kelen‐Tudos plot. Differential scanning calorimetric (DSC) measurements shows sharp melting peaks at about 64°C. Thermal stability studies were performed with thermogravimetric analyzer (TGA). By using these DSC and TGA data in several nonisothermal methods, the activation energies were calculated. X‐ray diffraction studies show the linearity of the copolymers. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2721–2726, 2003  相似文献   

5.
Fully bio‐based soy protein isolate (SPI) resins were toughened using natural rubber (NR) and epoxidized natural rubber (ENR). Resin compositions containing up to 30 wt % NR or ENR were prepared and characterized for their physical, chemical and mechanical properties. Crosslinking between SPI and ENR was confirmed using 1H‐NMR and ATR‐FTIR. All SPI/NR resins exhibited two distinctive drops in their modulus at glass transition temperature (Tg ) and degradation temperature (Td ) at around ?50 and 215 °C, corresponding to major segmental motions of NR and SPI, respectively. SPI/ENR resins showed similar Tg and Td transitions at slightly higher temperatures. For SPI/ENR specimens the increase in ENR content from 0 to 30 wt % showed major increase in Tg from ?23 to 13 °C as a result of crosslinking between SPI and ENR. The increase in ENR content from 0 to 30 wt % increased the fracture toughness from 0.13 to 1.02 MPa with minimum loss of tensile properties. The results indicated that ENR was not only more effective in toughening SPI than NR but the tensile properties of SPI/ENR were also significantly higher than the corresponding compositions of SPI/NR. SPI/ENR green resin with higher toughness could be used as fully biodegradable thermoset resin in many applications including green composites. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 44665.  相似文献   

6.
The effects of epoxidized natural rubber (ENR‐50) and processing parameters on the properties of natural rubber/ethylene–propylene–diene rubber (NR/EPDM; 70 : 30 phr) blends were studied. The compounds were prepared by melt compounding method. Using response surface methodology of two‐level full factorial, the effects of ENR‐50 contents (?1 : 5 phr; +1 : 10 phr), mixing temperature (?1 : 50°C; +1 : 110°C), rotor speed (?1 : 40 rpm; +1 : 80 rpm), and mixing time (?1 : 5 min; +1 : 9 min) in NR/EPDM blends were evaluated. Cure characteristics and tensile properties were selected as the responses. The significance of factors and its interaction was analyzed using ANOVA and the model's ability to represent the system was confirmed using the constant of determination, R2 with values above 0.90. It was found that the presence of ENR‐50 has the predominant role on the properties of NR/EPDM blends. The addition of ENR‐50 significantly improved cure characteristics and tensile strength up to 5.12% and 6.48% compared to neat NR/EPDM blends, respectively. These findings were further supported by swell measurement, differential scanning calorimetry, and scanning electron microscopy. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40713.  相似文献   

7.
The polynitro imidazole derivative 1,5‐dinitro‐2,6‐bis(trinitromethyl)‐3a,4a,7a,8a‐tetrahydro‐[1,4]dioxino[2,3‐d:5,6‐d′]diimidazole (DNTNDI) was synthesized through nitration of 2‐(dinitromethylene)‐1H‐imidazol‐4‐ol in HNO3/Ac2O followed by cyclization of the di‐enol. It was characterized by NMR, IR, elemental analysis, and single‐crystal X‐ray diffraction analysis. Compound DNTNDI crystallizes in the orthorhombic space group P2(1)2(1)2(1). The thermal decomposition was studied with thermogravimetry/derivative thermogravimetry (TG/DTG) in a nitrogen atmosphere with a heating rate of 5 K min−1. The TG/DTG analysis indicated that DNTNDI has 97.64 % mass loss between 127 °C and 173 °C by undergoing exothermic decomposition. The density of DNTNDI was determined as 1.906 g cm−3 at 293 K with an Ultrapycno 1000 Pycnometer. The denotation velocity and denotation pressure of DNTNDI were calculated as 9325 m s−1 and 40 GPa by applying the LOTUSES (version 1.4) code, respectively. The oxygen balance of DNTNDI is 0 and its oxygen content amounts to 51.78 %, which is superior to that of new generation of chlorine‐free oxidizer ammonium dinitramide (ADN).  相似文献   

8.
The unsaturated sites in oleic 2‐ethylhexyl estolide esters (containing 35 % monoenic fatty acids) were converted into epoxide and five‐membered cyclic carbonate groups and the products characterized by Fourier transform infrared spectra (FTIR), 1H, and 13C nuclear magnetic resonance (NMR) spectroscopies. Epoxidation of the alkene bonds was accomplished using performic acid generated in situ from formic acid and hydrogen peroxide. Greater than 90 % alkenes were converted into their corresponding epoxide groups as determined by oxirane values and the epoxide ring structure was confirmed by 1H and 13C NMR. The estolide ester epoxide material was subsequently reacted with supercritical carbon dioxide in the presence of tetrabutylammonium bromide catalyst to produce the corresponding estolide ester containing the cyclic carbonate group. The signals at 1,807 cm?1 and δ 82 ppm in the FTIR and 13C‐NMR spectra, respectively, confirmed the desired cyclic carbonate was produced. The carbonated estolide ester exhibited a dynamic viscosity, at 25 °C, of 172 mPa·s as compared to 155 mPa·s for the estolide ester starting material. The estolide ester structure of these new derivatives was shown to be consistent throughout their synthesis.  相似文献   

9.
Phenyl acetylene terminated poly(carborane‐silanec) (PACS) was synthesized by the couple reaction of methyldichlorosilane with 1,7‐dilithio‐m‐carborane and lithium phenylacetylide. The structure was characterized using FTIR, 1H‐NMR, 13C‐NMR, 29Si‐NMR, and gel permeation chromatography. PACS exhibits solubility in common organic solvents. Thermal and oxidative properties were evaluated by thermogravimetric analysis (TGA). Thermoset exhibits extremely thermal and oxidative property and TGA curves show that the temperature of 5% weight loss (Td5) is 762°C and char yield at 800°C is 94.2% in nitrogen. In air, surprisingly, both Td5 and char yield at 800°C show slight increase, which is greater than 800°C and 95.6%, respectively. After pyrolysis, the char has no additional weight loss up to 800°C in air. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 2498–2503, 2007  相似文献   

10.
Poly(vinyl alcohol) (PVA) can be dissolved in a nonaqueous medium in the presence of catalytic concentration of ethyl nitrate dimethyl sulfoxide, C2H5ONO2 · DMSO (EN · DMSO). From the PVA solution, poly(vinyl butyral) (PVBu) was prepared by acid‐catalyzed homogeneous acetalization of PVA with butyraldehyde. The formation of PVBu was confirmed by IR and 1H‐NMR spectra. The degree of acetalization of PVBu was found to be 95 mol %, which was verified by 1H‐NMR data and acetylation method. The molecular mass of the polymer was determined by GPC method. The glass transition temperature, Tg, was measured from differential scanning calorimetric (DSC) thermograms. Thermal stabilities were checked by thermogravimetric analysis (TGA) and differential thermogravimetry (DTG). The acetal decomposed in three stages. The corresponding initial decomposition temperatures were found to be 285, 390, and above 500°C. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 1182–1186, 2001  相似文献   

11.
The energetic material, 3‐nitro‐1,5‐bis(4,4′‐dimethyl azide)‐1,2,3‐triazolyl‐3‐azapentane (NDTAP), was firstly synthesized by means of Click Chemistry using 1,5‐diazido‐3‐nitrazapentane as main material. The structure of NDTAP was confirmed by IR, 1H NMR, and 13C NMR spectroscopy; mass spectrometry, and elemental analysis. The crystal structure of NDTAP was determined by X‐ray diffraction. It belongs to monoclinic system, space group C2/c with crystal parameters a=1.7285(8) nm, b=0.6061(3) nm, c=1.6712(8) nm, β=104.846(8)°, V=1.6924(13) nm3, Z=8, μ=0.109 mm−1, F(000)=752, and Dc=1.422 g cm−3. The thermal behavior and non‐isothermal decomposition kinetics of NDTAP were studied with DSC and TG‐DTG methods. The self‐accelerating decomposition temperature and critical temperature of thermal explosion are 195.5 and 208.2 °C, respectively. NDTAP presents good thermal stability and is insensitive.  相似文献   

12.
Thermal stability of a recently synthesized polymeric methyl‐di(phenylethynyl)silane (MDPES) resin was studied using a number of thermal and spectrometric analytical techniques. The polymer exhibits extremely high thermal stability. Thermogravimetric analysis (TGA) shows that the temperature of 5% weight loss (Td5) was 615°C and total weight loss at 800°C was 8.9%, in nitrogen atmosphere, while in air, Td5 was found to be 562°C, and total weight loss at 800°C was found to be 55.8% of the initial weight. Differential thermal degradation (DTG) studies show that the thermal degradation of MDPES resin was single‐stage in air and two‐stage in nitrogen. The thermal degradation kinetics was studied using dynamic TGA, and the apparent activation energies were estimated to be 120.5 and 114.8 kJ/mol in air, respectively, by Kissinger and Coats–Redfern method. The white flaky pyrolysis residue was identified to be silicon dioxide by FTIR and EDS, indicating that the thermal stability of polymer may be enhanced by the formation of a thin silicon dioxide film on the material surface. © 2006 Wiley Periodicals, Inc. J Appl PolymSci 103: 605–610, 2007  相似文献   

13.
Thermal stability and rheological properties of a novel surfactant–polymer system containing non‐ionic ethoxylated fluorocarbon surfactant was evaluated. A copolymer of acrylamide (AM) and 2‐acrylamido‐2‐methylpropane sulfonic acid (AMPS) was used. Thermal stability and surfactant structural changes after aging at 100 °C were evaluated using TGA, 1H NMR, 13C NMR, 19F NMR and FTIR. The surfactant was compatible with AM–AMPS copolymer and synthetic sea water. No precipitation of surfactant was observed in sea water. The surfactant was found to be thermally stable at 100 °C and no structural changes were detected after exposure to this temperature. Rheological properties of the surfactant–polymer (SP) system were measured in a high pressure rheometer. The effects of surfactant concentration, temperature, polymer concentration and salinity on rheological properties were studied for several SP solutions. At low temperature (50 °C), the viscosity initially increased slightly with the addition of the surfactant, then decreased at high surfactant concentration. At a high temperature (90 °C), an increase in the viscosity with the increase in surfactant concentration was not observed. Overall, the influence of the fluorocarbon surfactant on the viscosity of SP system was weak particularly at high temperatures and high shear rate. Salts present in sea water reduced the viscosity of the polymer due to a charge shielding effect. However, the surfactant was found to be thermally stable in the presence of salts.  相似文献   

14.
Epoxidized natural rubbers (ENRs) with epoxide levels of 10, 20, 30, 40, and 50 mol % were prepared. The ENRs were later blended with poly(methyl methacrylate) (PMMA) with various blend formulations. The mixing torque of the blends was observed. The torque increased as the PMMA contents and epoxide molar percentage increased in the ENR molecules. Furthermore, the shear stress and shear viscosity of the polymer blends in the molten state increased as the ENR content and epoxide molar percentage increased in the ENR molecules. Chemical interactions between polar groups in the ENR and PMMA molecules might be the reason for the increases in the torque, shear stress, and viscosity. All the ENR/PMMA blends exhibited shear‐thinning behavior. This was observed as a decrease in the shear viscosity with an increase in the shear rate. The power‐law index of the blends decreased as the ENR contents and epoxide molar percentage increased in the ENR molecules. However, the consistency index (or zero shear viscosity) increased as the ENR contents and epoxide molar percentage increased. A two‐phase morphology was observed with scanning electron microscopy. The small domains of the minor components were dispersed in the major phase. For the determination of blend compatibility, two distinct glass‐transition‐temperature (Tg) peaks from the tan δ/temperature curves were found. Shifts in Tg to a higher temperature for the elastomeric phase and to a lower temperature for the PMMA phase were observed. Therefore, the ENR/PMMA blends could be described as partly miscible blends. According to the thermogravimetry results, the decomposition temperatures of the blends increased as the levels of ENR and the epoxide molar percentage increased. The chemical interactions between the different phases of the blends could be the reason for the increase. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 3561–3572, 2004  相似文献   

15.
The cure index and apparent activation energy of vulcanization of one grade of natural rubber (SMR L) and two grades of epoxidized natural rubbers (ENR 25 and ENR 50) were studied in the presence of three types of antioxidants [viz., 2,2′methylene‐bis(4‐methyl‐6‐tertbutylphenol) (AO 2246), poly‐2,2,4‐trimethyl‐1,2‐dihydroquinoline (TMQ), and N‐isopropyl‐N′‐phenyl‐p‐phenylenediamine (IPPD)] in the temperature range of 120–180°C by using a Monsanto automatic Mooney viscometer. Accelerated sulfur vulcanization system and up to 5 phr of antioxidant concentration was used throughout the investigation. Results indicate that both cure index and apparent activation energy of vulcanization are dependent on the type and concentration of the antioxidant used. AO 2246 (a phenol‐based antioxidant) would retard vulcanization as reflected by the higher cure index and activation energy, an observation which is attributed to the solvation and steric hindrance effects of the antioxidant. On the contrary, both TMQ and IPPD (amine‐based antioxidants) exhibit reverse behavior due to the catalytic effect of the antioxidants in generating more active sulfurating agents for vulcanization. In all cases, SMR L gives higher cure index and apparent activation energy than the corresponding ENR, a phenomenon which is associated with the activation of the adjacent double bond by epoxide group in the latter. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 3234–3238, 2000  相似文献   

16.
Methyl‐tri(phenylethynyl)silane (MTPES) was successfully synthesized by the reaction of lithium phenylacetylide with methyltrichlorosilane. The structure was characterized by HRMS, FTIR, 1H‐NMR, 13C‐NMR, 29Si‐NMR, and elementary analysis. Thermal cure process was monitored by DSC, DMA, and FTIR. MTPES was heated to free flowing liquid around 130°C and thermally polymerized at 327–377°C to form thermoset. Thermal and oxidative properties were evaluated by TGA analysis. Thermoset exhibits extremely high heat‐resistance and TGA curve in nitrogen shows the temperature of 5% weight loss (Td5) of 695°C and total weight loss at 800°C of 7.1%. TGA shows a high Td5 of 565°C even in air, although the total weight loss at 800°C was 56.1% of the initial weight, much higher than that in nitrogen. The high heat resistance of MTPES was ascribed to crosslinking reaction concerning ethynyl groups. Aging studies performed at elevated temperatures in air on a thermoset showed that MTPES is oxidatively stable to 300°C. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 2488–2492, 2006  相似文献   

17.
The thermal stability of alkyl chitosan derivatives (RChi) and N,N,N‐trimethyl chitosan bearing different counter ions (TMCX) was assessed by means of TG analyses. Multistep TG curves were observed for TMCX regardless of the counter ion. They exhibited lower DTG peak temperatures (TMCCl/238.2°C, TMCBr/224.5°C, TMCI/222.6°C, and TMC‐SO4/237.0°C) as compared to the parent chitosan (306.4°C) while, in contrast, the RChi showed higher DTG temperatures (ButChi/311.7°C, OctChi/327.8°C, and DodecChi/306.3°C). The apparent activation energy values determined by using the isoconversional method revealed that the RChi derivatives have low activation energy (OctChi/111.6 ± 5 kJ/mol), whereas quaternary salts have high activation energy (TMCI/155.5 ± 10 kJ/mol). © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011  相似文献   

18.
《Polymer Composites》2017,38(6):1151-1157
Epoxidized natural rubbers (ENRs) with three different epoxide contents (i.e., 20, 35, and 50 mol% indicated as ENR20, ENR35, and ENR50, respectively) were prepared. They were then reinforced with 3‐methyacryloxypropyl trimethoxysilane‐modified nanosilica (MPTS‐SiO2). Influence of epoxide level in ENR molecules on morphological, mechanical, and dynamic mechanical properties of the ENR nanocomposites was investigated. The scanning electron microscopy results revealed larger agglomerates of SiO2 were found in the ENR composites with higher epoxide content. Furthermore, the strength and moduli of the ENR nanocomposites increased with increasing epoxide content. However, the optimal tensile strength and elongation at break were observed in the nanocomposites with the intermediate level of epoxide contents. The correlation between the strength properties and the interfacial silica‐matrix adhesion indicated that the maximum interfacial adhesion of the nanocomposites was observed in the nanocomposite with ENR35. Also, DMA results indicated stronger interaction between ENR35 and MPTS‐SiO2 due to higher storage modulus. POLYM. COMPOS., 38:1151–1157, 2017. © 2015 Society of Plastics Engineers  相似文献   

19.
Thermal analyses, including differential scanning calorimetry (DSC), thermogravimetry (TG), and differential thermogravimetry (DTG), were performed on a series of derivatives of cyclic ureas under nitrogen. Such compounds are used extensively for durable press finishing of cotton textiles. Three common features were discovered in 15 compounds analyzed. Two features related to the presence of an oxygen-containing substituent on the ring carbons or the ring nitrogens. The former substitution was expressed as an exothermic response between 200 and 300°C and the latter as an endotherm between 300 and 400°C. Specific substituent modifications that changed these responses are described. A final feature was identified. The presence of N-methylol groups was recognized. This represented the first evidence that compounds capable of releasing formaldehyde have a thermoanalytical marker. The amount of residue produced in TG analyses was related to structure and indicated that thermally induced polycondensations were occurring.  相似文献   

20.
2,5‐ Dichlorophenyl acrylate (DPA)‐co‐glycidyl methacrylate (GMA) polymers having five different compositions were synthesized in 1,4‐dioxane using benzoyl peroxide as a free‐radical initiator at 70 ± 0.5°C. Using 1H‐NMR spectroscopy, the composition of the two monomers in the copolymers was calculated by comparing the integral values of the aromatic and aliphatic proton peaks. The reactivity ratios were calculated by Fineman–Ross (r1 = 0.31 and r2 = 1.08), Kelen–Tudos (r1 = 0.40 and r2 = 1.15), and extended Kelen–Tudos (r1 = 0.39 and r2 = 1.16) methods. The nonlinear error‐in‐variables model was used to compare the reactivity ratios. The copolymers were characterized by 1H and proton decoupled 13C‐NMR spectroscopes. Gel permeation chromatography was performed for estimating the Mw and Mn and Mw/Mn of the poly(DPA) and copolymers (DPA‐co‐GMA: 09 : 91 and 50 : 50). Thermal stability of the homo‐ and copolymers was estimated using TGA [poly(DPA) > DPA‐co‐GMA (50 : 50) > DPA‐co‐GMA (09:91)], while DSC was utilized for determining the glass transition temperature. Tg increased with increased DPA content in the copolymer. The 50 : 50 mol % copolymer was chosen for curing with diethanolamine in chloroform. The cured resins were tested for the adhesive properties on leather at different temperatures (50, 90, 100, and 110°C). The resin cured at 50 °C exhibited a maximum peel strength of 1.6 N/mm, revealing a good adhesive behavior. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 1167–1174, 2006  相似文献   

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