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 15 毫秒
1.
Four polyols were prepared by a ring opening of epoxidized soybean oil with HCl, HBr, methanol, and by hydrogenation. Two series of polyurethanes were prepared by reacting the polyols with two commercial isocyanates: PAPI and Isonate 2143L. Generally, the properties of the two series were similar. The crosslinking density of the polyurethane networks was analyzed by swelling in toluene. Brominated polyols and their corresponding polyurethanes had the highest densities, followed by the chlorinated, methoxylated, and hydrogenated samples. The polyurethanes with brominated and chlorinated polyols had comparable glass transition and strength, somewhat higher than the polyurethane from methoxy containing polyol, while the polyurethane from the hydrogenated polyol had lower glass‐transition and mechanical properties. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 4062–4069, 2000  相似文献   

2.
Thermal analysis of soybean oil based polyols   总被引:3,自引:1,他引:2  
Soybean oil based polyols (5-OH polyol, 10-OH polyol and 15-OH polyol) were synthetised from epoxidized soybean oil. The melting peak of polyols and the relationship between melting peak and the number-average functionality of hydroxyl in polyols were investigated by differential scanning calorimetry (DSC). The thermal decomposition of polyols and some of their thermal properties by thermogravimetry (TG) and derivative thermogravimetry (DTG) were also studied. The thermal stability of polyols in a nitrogen atmosphere was very close hence they had a same baseplate of triglyceride for polyols. The extrapolated onset temperature of polyols in their thermal mass loss, first step had a decreasing order: 5-OH polyol>10-OH polyol>15-OH polyol due to the difficulty in forming multiple elements ring of them had the same order. The thermal behavior of polyols under non-isothermal conditions using Friedman’s differential isoconversional method with different heating rates indicated that the 5-OH polyol had the lowest activation energy in thermal decomposition amongst these polyols according to the same fractional mass loss because of the weakest intramolecular oligomerization. The 15-OH polyol was prior to reach the mass loss region because the six-member ring is more stable than the three-member ring from 10-OH polyol and more easily formed.  相似文献   

3.
We synthesized six polyurethane networks from 4,4′‐diphenylmethane diisocyanate and polyols based on midoleic sunflower, canola, soybean, sunflower, corn, and linseed oils. The differences in network structures reflected differences in the composition of fatty acids and number of functional groups in vegetable oils and resulting polyols. The number average molecular weights of polyols were between 1120 and 1300 and the functionality varied from 3.0 for the midoleic sunflower polyol to 5.2 for the linseed polyol. The functionality of the other four polyols was around 3.5. Canola, corn, soybean, and sunflower oils gave polyurethane resins of similar crosslinking density and similar glass transitions and mechanical properties despite somewhat different distribution of fatty acids. Linseed oil–based polyurethane had higher crosslinking density and higher mechanical properties, whereas midoleic sunflower oil gave softer polyurethanes characterized by lower Tg and lower strength but higher elongation at break. It appears that the differences in properties of polyurethane networks resulted primarily from different crosslinking densities and less from the position of reactive sites in the fatty acids. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 809–819, 2004  相似文献   

4.
New polymeric materials have been prepared by the cationic copolymerization of regular soybean oil, low saturation soybean oil, i.e. LoSatSoy oil, or conjugated LoSatSoy oil with styrene and divinylbenzene, norbornadiene or dicyclopentadiene initiated by boron trifluoride diethyl etherate (BF 3·OEt 2) or related modified initiators. The effects of the stoichiometry, the type of soybean oil and the alkene comonomer on the damping behavior of the resulting polymers have been investigated. The damping properties have been quantitatively evaluated by the loss tangent maximum (tan δ) max, ­the temperature range ΔT for efficient damping (tan δ > 0.3), and the integrals of the linear tan δ v. temperature curves (tan δ area, TA). These bulk materials are composed primarily of soybean oil‐styrene‐divinylbenzene random copolymers with considerable variability in the backbone compositions. The good damping properties of the soybean oil polymers are presumably determined by the presence of fatty acid ester side groups directly attached to the polymer backbone and the segmental heterogeneities resulting from crosslinking. In general, crosslinking reduces the (tan δ) max and the TA values, but broadens the region of efficient damping (ΔT). Soybean oil polymeric materials with appropriate compositions and crosslink densities are capable of efficiently damping over a temperature region in excess of 110 °C and provide noise and vibration attenuation over broad temperature and frequency ranges. Copyright © 2002 John Wiley & Sons, Ltd.  相似文献   

5.
Two kinds of bio‐resourced reactive diluents have been synthesized from linseed oil. The prepared epoxidized linseed oil (ELO) and the cyclocarbonated linseed oil (CLO) were separately blended with a petroleum‐based tetra‐functional epoxy resin (TGDDM) to improve its processability and to overcome the brittleness of the thermoset network therefrom. The linseed oil modifications were spectrally established, and processability improvement of the resin blends was rheologically confirmed. The curing of samples was studied by differential scanning calorimetry, and their mechanical properties (ie, tensile, flexural, fracture toughness, and adhesion) were investigated as well. Scanning electron microscopy images were obtained to reconfirm the toughness improvement of the modified thermosets. In contrast of the epoxidized soybean oil (ie, the most conventionally studied bio‐based reactive diluent), ELO and CLO had no negative effects on the thermoset material characteristics. They improved properties such as tensile strength (up to 43.2 MPa), fracture toughness (1.1 MPa m1/2), and peel‐adhesion strength (4.5 N/25 mm). It was concluded that ELO and CLO were efficient reactive diluents to be used in formulations of polymer composites, surface coatings, and structural adhesives based on epoxy resins.  相似文献   

6.
Oleic acid and α,ω‐diacid were converted into propargylic esters followed by thiol‐ene/yne coupling (TEC/TYC) functionalization in presence of mercaptoethanol. The multiradical addition on fatty esters leads to the formation of lipidic polyols (OH1 and OH2), as judged by 1H NMR and mass spectroscopies as well as by size exclusion chromatography. The crosslinking reaction between TEC/TYC‐based polyols and 4,4′‐methylene bis(phenylisocyanate) isocyanate reactant was monitored by FTIR experiment and reaction parameters were optimized. By differential scanning calorimetry, relatively high glass transitions are measured corresponding to structure with little or without dangling chain. Moreover, the thermal stability of the resulting plant oil‐based polyurethane materials (PU1 and PU2) were found to be fully consistent with that of other lipidic PUs respecting a three‐step process. Thanks to TYC methodology, fatty α,ω‐diacid produces lipidic polyol without dangling chain and lipidic thermoset PU with relatively high Tg. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 1597–1606  相似文献   

7.
Structure and properties of partially epoxidized soybean oil   总被引:1,自引:1,他引:0  
In the present study, the characteric-structure relationship of epoxidized soybean oils (ESO) with various degrees of epoxidation has been investigated. FTIR analysis was used to identify the relative extent of epoxidation of the samples during the epoxidation reaction. The viscosities of ESO were much higher than that of the raw oil, viscosity increased with degree of epoxidation. The viscous-flow activation energy of ESO was determined to be higher than that of the raw oil (20.72 to 77.93% higher). Thermogravimetry analysis (TG) of ESO was used to investigate the thermodynamic behavior of the samples. With increasing degree of epoxidation, the thermal stability of the samples initially decreased, then increased at the final reacting stage. Differential scanning calorimeter (DSC) indicated that the melting point of ESO was higher than that of soybean oil. Gel permeation chromatography (GPC) indicated the molecular mass of the samples increased initially, then decreased, with an increase in the extent of epoxidation.  相似文献   

8.
Polymers based on renewable sources are promising materials, and can find many uses in coatings and adhesive applications. The goal of this work was to synthesize and characterize bio‐based styrene/acrylated fatty acid methyl ester (AFAME) copolymer—poly(styrene‐co‐AFAME) prepared by miniemulsion polymerization. The main strategy adopted was to functionalize the bio‐monomer with acrylic acid that was confirmed by 1H NMR and FTIR measurements, to allow its free‐radical homo‐ or copolymerization with styrene. Poly(styrene‐co‐AFAME) with different AFAME content were obtained and their composition were evaluated by 1H NMR. Dynamic light scattering measurements throughout the reactions have indicated a very stable colloidal systems and average particles size ranges 100–150 nm. The structural and physical properties of poly(styrene‐co‐AFAME) were investigated by DTG‐DTA, DSC which displayed a decreasing of glass transition temperature with increase of AFAME content. The results showed in this study have indicated that the poly(styrene‐co‐AFAME) can be used in several fields because their characteristics are totally distinct. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 1422–1432  相似文献   

9.
A variety of new polymeric materials ranging from soft rubbers to hard, tough, and brittle plastics were prepared from the cationic copolymerization of regular soybean oil, low saturation soybean oil (LoSatSoy oil), or conjugated LoSatSoy oil with styrene and divinylbenzene initiated by boron trifluoride diethyl etherate (BF3 · OEt2) or related modified initiators. The relationship between the dynamic mechanical properties of the various polymers obtained and the stoichiometry, the types of soybean oils and crosslinking agents, and the different modified initiators was investigated. The room‐temperature storage moduli ranged from 6 × 106 to 2 × 109 Pa, whereas the single glass‐transition temperatures (Tg) varied from approximately 0 to 105 °C. These properties were comparable to those of commercially available rubbery materials and conventional plastics. The crosslinking densities of the new polymers were largely dependent on the concentration of the crosslinking agent and the type of soybean oil employed and varied from 74 to 4 × 104 mol/m3. The Tg increased and the intensity of the loss factor decreased irregularly with an increase in the logarithmic crosslinking densities of the polymers. Empirical equations were established to describe the effect of crosslinking on the loss factor in these new polymeric materials. The polymers based on conjugated LoSatSoy oil, styrene, and divinylbenzene possessed the highest room‐temperature moduli and Tg 's. These new soybean oil polymers appear promising as replacements for petroleum‐based polymeric materials. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 2721–2738, 2000  相似文献   

10.
11.
A mixture of epoxidized soybean oil (ESO), (R)‐12‐hydroxystrearic acid (HSA) and a photoinitiator for cationic polymerization in the ESO/HSA weight ratio 10/1 was heated to 100 °C and gradually cooled to room temperature to give bio‐based gelatinous material. The photo‐curing of the gel afforded a nanocomposite composed of crosslinked ESO and supramolecular HSA nanofibers. The transmission electron microscopy observation of the photo‐cured ESO/HSA revealed that dendritic clusters of HSA nanofibers are formed in the crosslinked ESO matrix. In the differential scanning calorimetry chart of the ESO/HSA, a thermal transition from the mesophase composed of supramolecular nanofibers to isotropic state was observed at 67 °C (ΔH = 22.6 J/g‐HSA), while the Tm of crystalline HSA is 77.7 °C (ΔHm = 159 J/g‐HSA). Tensile strength at 20 °C of the ESO‐HSA was ~80% higher than that of photo‐cured ESO without HSA. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 669–673, 2009  相似文献   

12.
A commercial vegetable oil‐based polyol for rigid polyurethane foams has been characterized by liquid chromatography‐electrospray ionization‐quadrupole ion trap mass spectrometry (LC‐ESI‐QIT‐MS). The absolute molecular weight (MW = 960) was measured by gel permeation chromatography (GPC) equipped with both refractive index (RI) detector and static laser light‐scattering detector (SLSD), which allowed further analysis by LC‐MS. The oligo‐polyol mixture was first separated in two elutes and then investigated by a deep multistage mass spectrometry (MSn) study and completed using NMR. The major constituents identified were regioisomers of propoxylated sucrose (nPO = 6–12), and the related esters of C16:0, C18:1, and C18:2 fatty acids had a mass ratio of 6:3:1. A comparison of fatty acids composition between the sample and palm oil demonstrated that the sample was initially prepared from the mixture of sucrose and palm oil by direct propoxylation. The MSn fragmentation studies validated the structure of propoxylated sucrose and the related fatty acids derivatives. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 255–262  相似文献   

13.
Polyesters based on polyols and sebacic acid, known as poly(polyol sebacate)s (PPS), are attracting considerable attention, as their properties are potentially useful in the context of soft‐tissue engineering applications. To overcome the drawback that PPSs generally display rather low strength and stiffness, we have pursued the preparation of nanocomposites based poly(mannitol sebacate) (PMS), a prominent example of this materials family, with cellulose nanocrystals (CNCs). Nanocomposites were achieved in a two‐step process. A soluble, low‐molecular‐weight PMS pre‐polymer was formed via the polycondensation reaction between sebacic acid and D‐mannitol. Nanocomposites with different CNC content were prepared by solution‐casting and curing under vacuum using two different profiles designed to prepare materials with low and high degree of crosslinking. The as‐prepared nanocomposites have higher stiffness and toughness than the neat PMS matrix while maintaining a high elongation at break. A highly crosslinked nanocomposite with a CNC content of 5 wt % displays a sixfold increase in Young's modulus and a fivefold improvement in toughness. Nanocomposites also exhibit a shape memory effect with a switch temperature in the range of 15 to 45 °C; in particular the materials with a thermal transition in the upper part of this range are potentially useful for biomedical applications. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 3123–3133  相似文献   

14.
Hydroxy‐terminated telechelic poly(vinyl ether)s with pendant oxyethylene chains were synthesized by the reaction of the CH3CH(OCOCH3)? O[CH2]4O? CH(OCOCH3)CH3/Et1.5AlCl1.5/THF‐based bifunctional living cationic polymers of 2‐methoxyethyl vinyl ether (MOVE), 2‐ethoxyethyl vinyl ether (EOVE), and 2‐(2‐methoxyethoxy)ethyl vinyl ether (MOEOVE) with water and the subsequent reduction of the aldehyde polymer terminals with NaBH4. The obtained poly(vinyl ether) polyols were reacted with an equimolar amount of toluene diisocyanates [a mixture of 2,4‐ (80%) and 2,6‐ (20%) isomers] to give water‐soluble polyurethanes. The aqueous solutions of these polyurethanes caused thermally induced precipitation at a particular temperature depending on the sort of the thermosensitive poly(vinyl ether) segments containing oxyethylene side chains. These polyurethanes also function as polymeric surfactants, lowered the surface tension of their aqueous solutions. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 1641–1648, 2010  相似文献   

15.
Two new triptycene‐containing bis(ether amine)s, 1,4‐bis(4‐aminophenoxy)triptycene ( 4 ) and 1,4‐bis(4‐amino‐2‐trifluoromethylphenoxy)triptycene ( 6 ), were synthesized, respectively, from the nucleophilic chloro‐displacement reactions of p‐chloronitrobenzene and 2‐chloro‐5‐nitrobenzotrifluoride with 1,4‐dihydroxytriptycene in the presence of potassium carbonate, followed by palladium‐catalyzed hydrazine reduction of the dinitro intermediates. The bis(ether amine)s were polymerized with six commercially available aromatic tetracarboxylic dianhydrides to obtain two series of novel triptycene‐based polyimides 8a – f and 9a – f by using a conventional two‐step synthetic method via thermal and chemical imidizations. All the resulting polyimides exhibited high enough molecular weights to permit the casting of flexible and strong films with good mechanical properties. Incorporation of trifluoromethyl groups in the polyimide backbones improves their solubility and decreases their dielectric constants. The fluorinated polyimides 9d and 9f derived from diamine 6 with 4,4′‐oxydiphthalic anhydride and 2,2‐bis(3,4‐dicarboxyphenyl)hexafluoropropane dianhydride (6FDA), respectively, could afford almost colorless thin films. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011  相似文献   

16.
The unconventional (5S,7R,8S,9R,10S)‐configurated (?)‐7‐(acetyloxy)‐12,12‐dichloro‐8‐hydroxy‐13,14,15,16‐tetranorlabdan‐11‐one ( 2 ) was synthesized via the HCl‐promoted hydrolysis of (7α)‐7,8‐(isopropylidenedioxy)‐14,15‐dinorlabdan‐11,13‐dione ( 5 ). Possible mechanistic pathways of the reaction are considered. Crystal and molecular structures of the isolated compound 2 were determined by single‐crystal X‐ray structure analysis.  相似文献   

17.
You J  Kelley RA  Crouse CC  Trushenski JT  Lydy MJ 《Talanta》2011,85(3):1291-1297
A trade-off exists between beneficial n-3 long-chain polyunsaturated acids and toxic persistent halogenated hydrocarbons (PHHs), both of which primarily originate from fish oil commonly used in fish feeds. Alternative lipid sources are being investigated for use in fish feeds to reduce harmful contaminant accumulation, hence, research is needed to evaluate PHHs in fish feeds with various lipid compositions. An analytical method was developed for PHHs including nine organochlorine insecticides (OCPs), 26 polychlorinated biphenyls (PCBs) and seven polybrominated diphenyl ethers (PBDEs) in fish feeds with differing proportions of fish oils and alternative lipid sources by GC-ECD after accelerated solvent extraction, gel permeation chromatography (GPC), and sulfuric acid cleanup. The GPC removed the majority of the neutral lipids and sulfuric acid treatment effectively destroyed the polar lipids. Thus, the combination of the two methods removed approximately 99.7% of the lipids in the extracts. The method detection limits were less than 5 ng/g dry weight (dw) for most PHHs, while recoveries were 75-118%, 67-105%, 69-92%, 63-100% and 94-144% with relative standard deviations of 0.2-39%, 0.3-20%, 0.5-12%, 1.5-18% and 1.5-15% for PHHs in five types of fish feeds made from different lipid sources. Although the source of lipid showed no impact on cleanup efficiency and the developed method worked well for all feeds, fish feeds with 100% fish oil contained background PHHs and more interference than feeds containing alternative lipids.  相似文献   

18.
Chlorine‐functionalized TEMPO‐capped polystyrenes were investigated using the matrix‐assisted laser desorption/ionization time‐of‐flight (MALDI‐TOF) technique. Amine‐ and acrylate‐functionalized agents and bifunctional TEMPO‐capped polystyrene were also analyzed to demonstrate the applicability of this method. Using this technique allowed to analyze the conversion of the chlorine function to an acrylate function, which was previously difficult to detect with other methods.

MALDI‐TOF mass spectrum of a polystyrene described in this article, as obtained with DHB as the matrix.  相似文献   


19.
The cure behavior and properties of oligomeric bisphenol A‐based PEEK‐like phthalonitrile (PN) are thoroughly examined in this article. The resin is easily processed from the melt at a relatively low temperature (150–200 °C) and the monomer cure occurs in a controlled manner as a function of the amine content and processing thermal conditions. Dynamic mechanical measurements and thermogravimetric analysis show that the polymer properties improve as the maximum PN postcure temperature is increased to 415 °C. The effects of the amine and polymer postcure conditions on the flexural and tensile properties of the PN polymer are investigated. The mechanical properties of the polymer are maximized after postcuring to moderate temperatures (330–350 °C). The polymer exhibits an average flexural strength and tensile strength at break of 117 and 71 MPa, respectively. After oxidative aging at 302 °C for 100 h, the polymer retains excellent mechanical properties. The average flexural and tensile strength retention of the polymers are 81 and 75%, respectively. Microscale calorimetric measurements reveal that the flammability parameters of the oligomeric PN are low compared to other thermosets. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 3769–3777  相似文献   

20.
A new series of side‐chain liquid‐crystalline dendrimers (LCDs) by grafting vinyl‐terminated phenyl benzoate‐based promesogens to a novel polypropyleneimine‐derived dendritic polyols are reported. Polarized optical microscopy and X‐ray diffraction studies show that both the compounds display a smectic‐A (SmA) mesophase. The second‐generation dendrimer bearing eight‐branched promesogens exhibits a more stable SmA mesophase with a wide mesomorphic temperature range. It is demonstrated that “promoting groups” in the structure of LCD for the enhancement of mesomorphic stability are unnecessary in the case of strong anisotropic interactions. In contrast to conventional LCDs, these two compounds possess reactive vinyl terminals that endow them with the potential for the preparation of polymeric materials. For the first time, a type of thermoset elastomers is explored from LCDs via hydrosilylation crosslinking reaction of vinyl terminals and siloxane crosslinker. Two‐dimensional X‐ray diffraction study indicates that the lamellar structures of original dendrimers are reserved in the elastomer networks. Stress–strain curves reveal that these elastomers exhibit excellent elasticity under successive uniaxial compression. The combination of anisotropic structures of rigid units and elasticity of flexible networks in this novel series of elastomers makes them promising candidates for the application in artificial muscles or cartilages. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013  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