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1.
Abstract

The mechanical properties of blends of poly (vinyl chloride) (PVC) and poly (styrene-block-(ethylene-co-butadiene)-block–styrene) (SEBS) were investigated using maleic anhydride grafted SEBS (SEBS-g-MAH) as a compatibiliser. The results indicated that addition of a small amount of SEBS-g-MAH during melt blending significantly improved the mechanical properties of PVC/SEBS blends. The impact strength of the compatibilised PVC/SEBS blends was found to reach a maximum of 53·5±2·78 KJ m?2 at room temperature and a maximum of 32·8±1·66 KJ m?2 at ?20°C at an SEBS-g-MAH loading level of 6 phr. The two glass transition temperatures of the components in the blends converged to some degree upon addition of SEBS-g-MAH for compatibilisation. At room temperature the dynamic storage modulus of the compatibilised blends was higher than that of the blends without compatibilisation. The size of the dispersed phase domains in the blends was appreciably reduced on addition of SEBS-g-MAH during melt blending according to scanning electron microscopy. All the above observations revealed that SEBS-g-MAH enhanced the compatibility between PVC and SEBS in the PVC/SEBS blends.  相似文献   

2.
A procedure to increase the adhesion of block styrene-butadiene-styrene (SBS) rubber consisting of the reactive grafting with maleic anhydride (MA) in the presence of an organic peroxide radical initiator is proposed. The influence of the reactive grafting on the surface properties of SBS has been studied with special emphasis on the improvement of the adhesion to polyurethane adhesive. The grafting of MA onto SBS was carried out in the presence of different concentrations of 2,5-dimethyl-2,5-di(tertbutyl peroxy) hexane (DBPH) as initiator to generate oxygen radicals by thermal decomposition, which induce the grafting reaction. The modification process was performed in the molten state using a Brabender mixer to premix the reactants and a hot press to initiate the functionalizing reaction. ATR-IR and XPS spectroscopies were employed to verify the grafting of MA on SBS. The changes in wettability on the modified SBS rubber were determined by contact angle measurements. Adhesion properties were evaluated from T-peel tests of SBS rubber/polyurethane adhesive joints. Reasonable extents of MA grafting on SBS were obtained (evidenced by the presence of a weak carbonyl vibration at 1700 cm-1 in the ATR-IR spectra and by the carbon- oxygen band at a binding energy of 287.0 eV in the XPS spectra). The higher the DBPH amount, the higher the MA amount grafted onto the SBS surface. The maximum grafting level was obtained using 2 wt% MA. Grafted species seemed to be mainly concentrated on the surface of the SBS-molded sheets. The wettability of the modified rubber increased with respect to the original polymer, new carbon-oxygen moieties were created and the C/O ratio increased. A noticeable enhancement in peel strength values was observed, which was ascribed to the creation of interfacial interactions between the polyurethane and the SBS rubber surfaces.  相似文献   

3.
Various copolymers of n-butyl methacrylate (nBMA)-maleic anhydride (MA) were synthesized by free radical solution polymerization using xylene as a solvent, with monomer ratio of (nBMA/MA) 80/20, 65/35 and 50/50 wt%. The nBMA/MA copolymers were analyzed by Fourier transform infrared spectroscopy (FTIR), proton nuclear magnetic resonance (1H NMR), gel permeation chromatography (GPC) differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), rheology, acid value, microhardness and friction resistance. The formation of the nBMA/MA copolymers was proven by FTIR and 1H NMR. The conversion percentage, glass transition temperature (Tg), thermal stability, hardness and the friction resistance of the nBMA/MA copolymers increased with the MA contents in the copolymers. All copolymers presented a thinning-shear rheological behavior due to the presence of entanglements. All films of the copolymers showed a good chemical resistance to HCl and NaCl solutions, but in the presence of NaOH solutions the films exhibited a blister.  相似文献   

4.
Poly(ester-urethane-imide)s were prepared by Diels–Alder polyaddition of 1,6-hexamethylene-bis(2-furanylmethylcarbamate) with various bismaleimides containing ester groups in the backbone. The Diels–Alder reaction was carried out in m-cresol, at 110°C, followed by thermal and chemical aromatization of tetrahydrophthalimide intermediates. The monomers and polymers were characterized by IR, 1H-NMR spectroscopy and elemental analysis. Thermal properties of the polymers were investigated by differential scanning calorimetry and dynamic thermogravimetric analysis.  相似文献   

5.
A series of amphiphilic graft copolymers PEO-g-PCL with different poly (ε-caprolactone) (PCL) molecular weight were successfully synthesized by a combination of anionic ring-opening polymerization (AROP) and coordination-insertion ring-opening polymerization. The linear PEO was produced by AROP of ethylene oxide (EO) and ethoxyethyl glycidyl ether initiated by 2-(2-methoxyethoxy) ethoxide potassium, and the hydroxyl groups on the backbone were deprotected after hydrolysis. The ring-opening polymerization of CL was initiated using the linear poly (ethylene oxide) (PEO) with hydroxyl group on repeated monomer as macroinitiator and Sn(Oct)2 as catalyst, then amphiphilic graft copolymers PEO-g-PCL were obtained. By changing the ratio of monomer and macroinitiator, a series of PEO-g-PCL with well-defined structure, molecular weight control, and narrow molecular weight distribution were prepared. The expected intermediates and final products were confirmed by 1H NMR and GPC analyzes. In addition, these amphiphilic graft copolymers could form spherical aggregates in aqueous solution by self-assemble, which were characterized by transmission electron microscopy, and the critical micelle concentration values of graft copolymers PEO-g-PCL were also examined in this article.  相似文献   

6.
The purpose of this study was the production of copolymers and terpolymers with highly hydrophilic–hydrophobic properties, using inexpensive and available monomers as potential enhancing oil recovery (EOR) and water production control agents for high-temperature and high-salinity (HTHS) oil reservoirs. For this purpose, several copolymers and terpolymers with different molar percentage of acrylamide/styrene, acrylamide/maleic anhydride, and acrylamide/styrene/maleic anhydride were synthesized by the inverse emulsion polymerization technique. The presence of hydrophobic styrene and hydrophilic maleic anhydride monomers in the copolymer and terpolymer structure, provided some unique properties compared to polyacrylamide, was confirmed by several analyses including HNMR, elemental analysis, FTIR, SEM, TGA, and DSC. Simulating HTHS oil reservoir condition under high salinity, temperature, and shear rate, the rheological studies suggested unlike traditional EOR agents such as polyacrylamide, the viscosity of the copolymer, and terpolymer aqueous solutions showed a considerable increase after a critical polymer concentration and less reduction with the salt increment at both ambient and elevated temperatures. Furthermore, the swelling ratio of the insoluble terpolymers measured versus the time and temperature in salt water increased with the maleic anhydride mole fraction, decreased with the salt concentration, and showed a maximum value at around 57 °C. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47753.  相似文献   

7.
8.
Based on hydrogen bonding interactions, Poly(methyl methacrylate-co-N-vinyl-2-pynolidone) (P(MMA-co-VP)) networks and linear poly(ethylene glycol) (PEG) can form semi-interpenetrating polymer networks (semi-IPNs), i.e. P(MMA-co-VP)/PEG semi-IPNs, which has shape memory behaviour; its maximum storage modulus ratio can be more than 400, and its shape recovery ratio could reach 99%. The morphology, thermal behaviors and dynamic mechanical properties of P(MMA-co-VP)/PEG semi-IPNs were studied by FTIR, TEM, DSC and DMA. When PEG with higher molecular weight was introduced into P(MMA-co-VP) networks, they possess higher glassy state modulus and higher recovering rate. In such a system, the maximum molecular weight of PEG required for the semi-IPN formation reaches 1000.  相似文献   

9.
The sorption properties of composites based on 2-acrylamido-2-methyl-1-propane sulfonic acid and montmorillonite are presented. Gel-type composites were obtained via in situ polymerization. Resin particles presented exfoliated morphologies, as suggested by X-ray diffraction. The addition of montmorillonite resulted in enhanced mechanical properties, as evaluated by Vickers microhardness tests. The swelling performances of the resins exhibited a fast initial water uptake, reaching the maximum absorption capacity after less of 1 h of contact. A batch procedure was used to evaluate the sorption characteristics of the composites, and the effects of pH, montmorillonite content, and time were studied. The composites showed high adsorption capacities at pH values of 3.0 and 5.0, and the addition of montmorillonite did not result in a significant enhancement of their adsorption capacity. The equilibrium adsorption performance can be described by the Langmuir isotherm, while kinetic experiments revealed an excellent agreement with the pseudo-second-order model.  相似文献   

10.
With the advance of the thermoplastic plastic elastomer (TPE) technology, there are growing interest and needs for using these materials in the meltblowing process where benefits of small fiber diameters of meltblowns can be combined with rubber-like elastic properties of elastomers. Performances and utilities of wide ranges of meltblown products such as facemask, medical barrier, wound-care, diaper can be drastically improved with additions of TPE. In this study, a new elastomeric meltblown fabric was successfully made with the styrene–ethylene/butylene–styrene (SEBS) block copolymer, and the relationship among structure, tensile properties, and meltblowing process parameters are studied. We found that median fiber diameter increases with the polymer mass throughout and decreases with air pressure, and fabric solidity has significantly influenced by die collector distance (DCD). The pore sizes of the fabrics are directly influenced by fiber diameters at the given DCD, but higher DCD increases the pore size due to their open structures. All SEBS nonwovens exhibit high strain at break, larger than 400%. Processing parameters significantly affect tensile properties, and this can be attributed to the fabric structure changes. The reduction of fiber diameter tends to increase the tensile strength of the fabric as it created more fiber-to-fiber bond points.  相似文献   

11.
Star-shaped copolymers with four and six poly(ε-caprolactone)-block-poly(N-vinylcaprolactam) (S(PCL-b-PNVCL)) arms were successfully synthesized by combining ring opening polymerization (ROP) of ε-caprolactone (CL) and reversible addition-fragmentation chain transfer (RAFT) polymerization of N-vinylcaprolactam (NVCL). The resulting star copolymers were characterized using 1H NMR, GPC and UV–vis. The numbers of arms in the star-shaped PCL-b-PNVCL block copolymers were demonstrated using degradation studies under acidic conditions, and the individual PNVCL chains were characterized by GPC and 1H NMR. In aqueous solution, star-shaped PCL-b-PNVCL block copolymers self-assembled into large aggregates or micelles with sizes varying from 54 to 300 nm, depending on the molecular weight of the copolymer and the relative lengths of the hydrophobic and hydrophilic segments. Micelles were characterized by atomic force microscopy (AFM), dynamic light scattering (DLS) and scanning electron microscopy (SEM).  相似文献   

12.
13.
Styrene (St) and maleic anhydride (MA) alternating copolymers with different molecular weights (MW) were synthesized via radical copolymerization. The copolymers were subsequently transferred into water-soluble maleic amic acid derivatives (SMAA) via the aminolysis of anhydride groups using (NH4)2CO3 as the ammonia sources. The synthesized polymers were applied as a new kind of macromolecular modifier and added into the reaction system during the synthesis of urea-formaldehyde (UF) resins via the traditional alkaline–acidic–alkaline three-step process. The UF resins modified with SMAA were characterized using Fourier Transform Infrared Spectroscopy (FT-IR), 13C nuclear magnetic resonance (13C-NMR) spectroscopy, and thermal gravimetric analysis (TGA). All the results confirmed the successful incorporation of SMAA chains into the crosslinking network of the UF resins. The modified UF resins were further employed as wood adhesives and the effect of synthesis parameters on their performance was investigated. Meanwhile, the influence of SMAA molecular weight (MW) on the properties of the modified UF resins was also studied. When the UF resins were synthesized with a low molar ratio of formaldehyde/urea (F/U) and a predetermined amount of SMAA added into the reaction system at the second step, plywood bonded using these modified UF resins showed much improved bonding strength (BS) and depressed formaldehyde emission. Moreover, the as-modified UF resins showed good storage characteristics.  相似文献   

14.
The synthesis of a new coil–rod–coil ABA triblock copolymers comprised of regioregular poly(3-hexylthiopene) (P3HT) and poly(methyl methacrylate) (PMMA) segments has been demonstrated by the combination of quasi-living Grignard metathesis (GRIM) polymerization and living anionic polymerization based on 1,1-diphenylethylene (DPE) chemistry. The method involves simple reaction steps, an in situ introduction of DPE moieties at the α,ω-ends of P3HT and the lithiation with sec-butyl lithium (sec-BuLi) to generate a macroinitiator bearing 1,1-diphenylalkyl anions, followed by cross-over to MMA. The selective α,ω-ends di-functionalization is a key step to achieve the ABA structure. The structural homogeneity of the precursor and block copolymer has been confirmed by gel permeation chromatography (GPC), GPC-right angle laser light scattering (RALLS), and nuclear magnetic resonance (NMR). The block copolymer has been fully characterized by differential scanning calorimetry (DSC), thermogravimetry analysis (TGA), Ultra-violet–visible (UV–vis) and photo luminescent (PL) spectroscopies, and atom force microscopy (AFM).  相似文献   

15.
This paper is devoted to preparation of gold–copper bimetallic nanoparticles deposited on inorganic supporters followed by their use in hydrogen peroxide decomposition and oxidation of ethylbenzene. The bimetallic nanoparticles of Au–Cu at molar ratio of 1:1 were synthesized by hydrothermal method in the presence of stabilizing agent—poly (N-vinyl-2-pyrrolidone) and reducing agent—glycine. The bimetallic nanoparticles were characterized by UV–Vis spectroscopy, DLS, and TEM techniques. The catalytic activity of Au–Cu bimetallic nanoparticles was evaluated with respect to decomposition of hydrogen peroxide and oxidation of ethylbenzene.  相似文献   

16.
A new family of biodegradable amino acid-based poly(ether ester amide)s (AA-PEEAs) consisting of three building blocks [poly(ε-caprolactone) (PCL), L -phenylalanine (Phe), and aliphatic acid dichloride] were synthesized by a solution polycondensation. Using DMA as the solvent, these PCL-containing Phe-PEEA polymers were obtained with fair to very good yields with weight average molecular weight (Mw) ranging from 6.9 kg/mol to 31.0 kg/mol, depending on the original molecular weight of PCL. The chemical structures of the PCL-containing Phe-PEEA polymers were confirmed by IR and NMR spectra. These PCL-containing Phe-PEEAs had lower Tg than most of the oligoethylene glycol (OEG) based AA-PEEAs due to the more molecular flexibility of the PCL block in the backbones, but had higher Tg than non-amino acid based PEEA. The solubility of the PCL-containing Phe-PEEA polymers in a wide range of common organic solvents, such as THF and chloroform, was significantly improved when comparing with aliphatic diol based poly(ester amide)s and OEG based AA-PEEAs. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012  相似文献   

17.
Biodegradable polyrotaxane (PR)-based triblock copolymers were synthesized via the atom transfer radical polymerization (ATRP) of N-isopropylacrylamide (NIPAAm) initiated with polypseudorotaxanes (PPRs) consisting of a distal 2-bromopropiomyl bromide end-capping poly(ε-caprolactone) (Br-PCL-Br) and a varying amount of α-cyclodextrins (α-CDs) in the presence of Cu(I)Br/PMDETA at 25 °C in aqueous solution. The copolymers were featured by relatively higher yields from 46.0% to 82.8% as compared with previous reports. Their structure was characterized in detail by using 1H NMR, 13C CP/MAS NMR, GPC, WXRD, DSC and TGA analyses. When a feed molar ratio of NIPAAm to Br-PCL-Br was changed from 50 to 200, the degree of polymerization of PNIPAAm blocks attached to two ends of PPRs was in a range of 158–500. About one third of the added α-CDs were still entrapped on the central PCL chain after the ATRP process. Attaching PNIPAAm rendered the copolymers soluble in aqueous solution showing the thermo-responsibility as evidenced by turbidity measurements.  相似文献   

18.
Abstract

Thermorheological properties of thermoplastic elastomeric 60/40, 70/30 and 80/20 nitrile rubber (NBR)/scrap computer plastics (SCP) blends were studied by using parallel plate rheometer. The blends exhibit pseudoplasticity and obey power law model. The dynamically vulcanised blends have higher dynamic viscosities than their unvulcanised counterparts. Surface finish and die swell of the extrudates are improved upon dynamic vulcanisation. The thermoplastic elastomeric blends of NBR/SCP exhibit 'thermorheological complexity'.  相似文献   

19.
Poly(N-isopropylacrylamide) (PNIPAM) hydrogels were simply prepared by free radical polymerization in different methanol–water mixture. A scanning electron microscopy study revealed that the freeze-dried hydrogels were macroporous. The swelling ratios in water at 20°C of the resulting hydrogels followed the order: X0.43>X0.21>X0.76 ≈ X0.57>X0.31>X0.13>X0.06>X0, where Xm denotes a gel prepared in a methanol–water mixture with m mole fraction of methanol (xm). Below the lower critical solution temperature, the swelling ratio values of all of the hydrogels gradually decreased with the increase in the temperature. The complete collapse of the PNIPAM chain of all the gels occurred at about 38°C, whereas the same was observed at about 35°C for the conventional gel prepared in water. The swelling ratio values of all the PNIPAM gels in the methanol–water mixtures with different xm values at 20°C passed through a minimum in the cononsolvency zone. The deswelling rates of the hydrogels decreased in the following order: X0.43> X0.31> X0.21> X0.57> X0.76 ≈ X0.13> X0.06> X0. The reswelling rates of these hydrogels decreased in the following order: X0> X0.31> X0.06 ≈ X0.13 > X0.76> X0.57> X0.21> X0.43. The release rates of the Tramadol Hydrochloride drug at 37°C from the drug-loaded hydrogels were almost same for all of the hydrogels. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012  相似文献   

20.
《Polymer》1987,28(5):831-836
Uncatalysed polymerizations of β-propiolactone with low-molecular-weight poly(ethylene glycol)s were carried out in bulk, at temperatures in the range of 70 to 120°C. 1H nuclear magnetic resonance (n.m.r.) and differential scanning calorimetry (d.s.c.) measurements on the resulting products indicated a block copolymer structure. Gel permeation chromatography (g.p.c.) and d.s.c. analyses showed that in some cases the copolymerization is accompanied by homopolymerization of β-propiolactone, probably due to the presence of residual water in the poly(ethylene glycol). N.m.r. and infra-red (i.r.) spectra of copolymers revealed the presence of hydroxyl and carboxyl end groups. The copolymerization reaction may be visualized as a two-step process, in which the ring opening of β-propiolactone takes place on both the hydroxyl groups of poly(ethylene glycol), followed by repetitive monomer addition forming an ester-ether-ester triblock copolymer.  相似文献   

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