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1.
N′‐Acryloyl benzhydrazide (ABH) was examined as a thermal stabilizer and costabilizer for rigid poly(vinyl chloride) (PVC) in air at 180°C. Its high stabilizing efficiency was shown by its high thermal stability value (Ts) when compared with those of two common reference stabilizers used industrially, dibasic lead carbonate (DBLC) and a calcium–zinc soap. Blending this organic stabilizer with the reference stabilizers in different ratios had synergistic effects on both the thermal stability and the extent of discoloration of the PVC. The Ni2+ complex of ABH gave better thermal stability and lesser discoloration than the parent organic stabilizer. Also, blending that complex with DBLC in different ratios gave better stability and lower discoloration. Thermogravimetric analysis confirmed the improved stability of PVC in the presence of the ABH stabilizer. J. VINYL ADDIT. TECHNOL., 2008. © 2008 Society of Plastics Engineers.  相似文献   

2.
Poly(N‐isopropylacrylamide) (PNIPA)/silica composite hydrogels were prepared and the effects of the silica incorporation on the swelling and breaking characteristics of the hydrogels were investigated. To improve the dispersive property of silica in the PNIPA matrix via the formation of covalent bonds between the polymer and silica, vinyl groups were introduced in the silica by reacting it with a coupling agent, 3‐methacryloxypropyltrimethoxysilane. When unmodified silica was used as filler in the PNIPA‐composite hydrogel, the swelling ratio of the composite hydrogel below the critical gel transition temperature (CGTT) increased with increasing silica content. However, when the modified silica was used as the filler, the swelling ratio below CGTT decreased with increasing silica content because of the enhanced distribution and additional crosslinking. Above CGTT, the swelling ratios of the PNIPA/silica hydrogels were similar regardless of the silica modification. The gel breaking stress of the hydrogels increased with increasing silica content, and this enhancement was larger for the modified silica hydrogel. Scanning electron microscopy images showed that the modified silica particles were distributed more evenly in the PNIPA matrix than the unmodified ones were and that the size of cell‐like structure of the hydrogel decreased with increasing modified silica content. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers  相似文献   

3.
Poly(N‐isopropylacrylamide‐co‐sodium acrylate) [poly(NIPAM‐co‐SA)] hydrogels were modified with three different kind of surfactants (cationic, anionic, and nonionic) to study the effect on the swelling properties. The structural variation of the surfactant‐modified hydrogels was investigated in detail. The interaction between the surfactants and the hydrogel varies and strictly depends on the surfactant type. The variation in thermal stability of the modified surfactant hydrogels was investigated and compared with unmodified hydrogel. Further, the hydrogel swelling/diffusion kinetic parameters were investigated and diffusion of water into hydrogel was found to be of the non‐Fickian transport mechanism. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 3423–3430, 2007  相似文献   

4.
Three types of N[4‐(N‐substituted amino carbonyl)phenyl] maleimide (RPhMI:N‐substituent (R) = phenyl, cyclohexyl, p‐chlorophenyl) were grafted onto poly(vinyl chloride) (PVC) films by using gamma irradiation. The effects of different parameters on the graft yield were investigated. These parameters included radiation dose and monomer concentration. Thermal properties of the grafted polymer were investigated by the determination of dehydrochlorination rate, thermal gravimetric behavior, and UV stability.  相似文献   

5.
Poly(vinyl chloride) (PVC) resin was modified by grafting the non‐ionic surfactant poly(oxyethylene 20 sorbitan) monolaurate (Tween® 20) using isocyanate chemistry. PVC was aminated using ethylenediamine and coupled with hexamethylene diisocyanate. Tween 20 was then reacted with the polymer, resulting in the grafting of the surfactant. The polymer modification was confirmed using infrared and X‐ray photo‐electron spectroscopy. Films of modified polymer were cast from a solution of tetrahydrofuran. The surface of films prepared from the modified polymer showed increased hydrophilicity as evidenced by contact‐angle measurements. The solid/water free energy of the modified polymer surface was nearly a quarter of the energy of the bare PVC surface. Static platelet adhesion studies using platelet‐rich plasma demonstrated significantly reduced adhesion onto a modified PVC surface compared with unmodified PVC. Data obtained demonstrate that modification of polymers with Tween 20 may be an interesting way of imparting protein‐ and cell‐repelling characteristics to them, thereby improving their blood‐compatibility. Copyright © 2005 Society of Chemical Industry  相似文献   

6.
A series of bionanocomposite (BNC) materials based on isoleucine containing poly(amide‐imide) (PAI) and modified MgAl‐layered double hydroxide (LDH) were prepared by solution intercalation method for the first time. An optically active PAI was synthesized by direct polycondensation reaction of N,N'‐(pyromellitoyl)‐bis‐isoleucine with 3,5‐diamino‐N‐(thiazol‐2‐yl)benzamide under green conditions. Organically modified LDH was prepared via ion exchange reaction of MgAl‐LDH in a solution of N,N'‐(pyromellitoyl)‐bis‐l‐ isoleucine in distilled water. X‐ray diffraction (XRD) results of modified LDH show an increase in interlayer distance as compared to the unmodified one. The obtained polymer and modified LDH were used to prepare chiral and high‐performance hybrid materials. Fourier transform infrared spectroscopy, XRD, field emission scanning electron microscopy, transmission electron microscopy, and thermogravimetric analysis (TGA) techniques were used to study the morphology and thermal properties of the obtained hybrid materials. TGA data indicated an increase in thermal stability of the BNCs as compared to the pure polymer. POLYM. COMPOS., 37:3288–3295, 2016. © 2015 Society of Plastics Engineers  相似文献   

7.
The thermal degradation behavior of poly (vinyl chloride), PVC, in presence of poly(N‐acryloyl‐N′‐cyanoacetohydrazide), PACAH, has been studied using continuous potentiometric determination of the evolved HCl gas from the degradation process from one hand and by measuring the extent of discoloration of the degraded samples from the other. The efficiency of blending PACAH with dibasic lead carbonate, DBLC, conventional thermal stabilizer has also been investigated. A probable radical mechanism for the effect of PACAH on the thermal stabilization of PVC has been proposed. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008  相似文献   

8.
Chlorinated poly(vinyl chloride) (CPVC) membranes for microfiltration processes were prepared with the combined process of a solvent evaporation technique and the water‐vapor induced‐phase‐inversion method. CPVC membranes with a mean pore size of 0.7 μm were very hydrophobic. These membranes were subjected to surface modification by ultraviolet (UV)‐assisted graft polymerization with N‐vinyl‐2‐pyrrolidinone (NVP) to increase their surface wettability and decrease their adsorptive fouling. The grafting yields of the modified membranes were controlled by alteration of UV irradiation time and NVP monomer concentration. The changes in chemical structure between the CPVC membrane and the CPVC‐g‐poly(N‐vinyl‐2‐pyrrolidinone) membrane and the variation of the topologies of the modified PVC membranes were characterized by Fourier transform infrared spectroscopy, gel permeation chromatography, and field emission scanning electron microscopy. According to the results, the graft yield of the modified CPVC membrane reached a maximum at 5 min of UV exposure time and 20 vol % NVP concentration. The filtration behavior of these membranes was investigated with deionized water by a crossflow filtration measurement. The surface hydrophilicity and roughness were easily changed by the grafting of NVP on the surface of the CPVC membrane through a simultaneous irradiation grafting method by UV irradiation. To confirm the effect of grafting for filtration, we compared the unmodified and modified CPVC membranes with respect to their deionized water permeation by using crossflow filtration methods. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 3188–3195, 2003  相似文献   

9.
N‐Phenylmaleimide–N‐(p‐hydroxy)phenylmaleimide–styrene terpolymer (HPMS), carrying reactive p‐hydroxyphenyl groups, was prepared and used to improve the toughness of cyanate ester resins. Hybrid modifiers composed of N‐phenylmaleimide–styrene copolymer (PMS) and HPMS were also examined for further improvement in toughness. Balanced properties of the modified resins were obtained by using the hybrid modifiers. The morphology of the modified resins depends on HPMS structure, molecular weight and content, and hybrid modifier compositions. The most effective modification of the cyanate ester resin was attained because of the co‐continuous phase structure of the modified resin. Inclusion of the modifier composed of 10 wt% PMS (Mw 136 000 g mol?1) and 2.5 wt% HPMS (hydroxyphenyl unit 3 mol%, Mw 15 500 g mol?1) led to 135% increase in the fracture toughness (KIC) for the modified resin with a slight loss of flexural strength and retention of flexural modulus and glass transition temperature, compared with the values for the unmodified resin. Furthermore, the effect of the curing conditions on the mechanical and thermal properties of the modified resins was examined. The toughening mechanism is discussed in terms of the morphological and dynamic viscoelastic behaviour of the modified cyanate ester resin system. © 2001 Society of Chemical Industry  相似文献   

10.
A new method of surface chemical modification of nano‐SiO2 was proposed in the paper. In the presence of catalyst, the active hydroxyl groups on the surface of nano‐SiO2 reacted with AB2‐type monomer (N,N‐dihydroxyethyl‐3‐amino methyl propionate) by one‐step polycondensation. And the product's Fourier transform infrared graphs and transmission electron microscopy (TEM) images proved that hyperbranched poly(amine‐ester) (HPAE) was grafted from nano‐SiO2 surface successfully. Moreover, polyvinyl chloride (PVC)/modified nano‐SiO2 composites were made by melt‐blending. The composites' structures and mechanical properties were characterized by TEM, scanning electron microscopy, and electronic universal testing machine. The results showed that nano‐SiO2 grafted by HPAE increased obviously in dispersion in PVC matrix, and mechanical properties of PVC were effectively improved. Additionally, it was found that mechanical properties of PVC/nano‐SiO2 composites reached the best when weight percent of nano‐SiO2 in PVC matrix was 1%. Compared with crude PVC, the tensile strength of HPAE grafted nano‐SiO2/PVC composite increased by 24.68% and its break elongation, flexural strength, and impact strength increased by 15.73, 4.07, and 184.84%, respectively. POLYM. COMPOS., 2008. © 2008 Society of Plastics Engineers  相似文献   

11.
N‐Phenyl‐3‐substituted 5‐pyrazolone derivatives were investigated as organic photostabilizers for rigid poly(vinyl chloride) (PVC). Their stabilizing efficiency was evaluated by the determination of the weight loss of the polymer after irradiation for different periods and by the determination of the amount of gel formation as well as the intrinsic viscosity of the soluble fraction of the degraded polymer. Moreover, the efficiency was evaluated from the extent of the discoloration of the degraded polymer. This was attributed not only to the radical trapping potency of the pyrazolone derivatives, which intervened with the radical degradation species in the degradation process of PVC, but also to the blocking of the newly formed radical sites on the polymeric chains. Their stabilizing efficiencies were compared with those of phenyl salicylate and 2‐hydroxy‐4‐(octyloxy)phenyl benzophenone, industrially known UV absorbers. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1543–1555, 2006  相似文献   

12.
The use of vegetable‐oil‐based polymeric plasticizers with nanotechnology can create new applications for plasticized poly(vinyl chloride) (PVC). Epoxidized Mesua ferrea L. (Ceylon Ironwood) seed oil was used as a plasticizer for PVC. Further, nanocomposites were prepared through an ex‐situ technique using epoxidized‐oil‐swelled organically modified montmorillonite (5 wt%) and PVC. Notable improvement in thermal and processing characteristics of the nanocomposites was observed over those of the virgin polymer (in both unplasticized and plasticized PVC), as studied by TGA. The prepared nanocomposites were characterized by FTIR, SEM, TEM, and XRD techniques. A dramatic decrease in viscosity (7‐fold) was observed in THF for a 10% solution of epoxidized‐oil‐modified PVC compared to unplasticized PVC in THF, as measured by Brookfield viscometer. Isothermal analysis at three different temperatures (100, 150, and 200°C) reveals sufficient stability of the epoxidized oil modified PVC nanocomposites, as confirmed by gravimetric and FTIR analysis. Augmentation of thermostability and good retention of mechanical properties of the (Mesua ferrea L.)‐plasticized‐PVC/clay nanocomposites with respect to rigid PVC vouch for the utility of the former as advanced industrial materials. J. VINYL ADDIT. TECHNOL., 18:168–177, 2012. © 2012 Society of Plastics Engineers  相似文献   

13.
The main objective of this research was to synthesize a new compatibilisant agent (PVC‐g‐MA), which was grafted from the maleic anhydride on the PVC chains. The presence of maleic anhydride grafting on PVC was made evident by infrared analysis. PVC‐g‐MA was used like compatibilisant to solve the problem of the incompatibility between the hydrophobic polymeric matrix (PVC) and hydrophilic fiber (alfa). Composites samples were prepared with different alfa fiber loading (10, 20, and 30 wt %) and incorporating PVC‐g‐MA (1, 3, and 5 wt %) or PP‐g‐MA (3 wt %). The tensile properties, the thermal stability and the morphology of the composites were investigated. The result indicated that the PVC‐g‐MA increased the interfacial adhesion between the fibers and the polymer matrix and this effect was better than that obtained for the maleated‐polypropylene‐coupled composites. Microstructure analysis of the fractured surfaces of MAPP modified composites confirmed improved interfacial bonding. The addition of alfa and PVC‐g‐MA increased the thermal stability of the composites. The temperature of degradation of the polymer matrix increased about 16°C in comparison to the noncoupled composite, indicating that PVC‐g‐MA improved the thermal stability of the polymer. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012  相似文献   

14.
Poly[aniline‐coN‐(2‐hydroxyethyl) aniline] was synthesized in an aqueous hydrochloric acid medium with a determined feed ratio by chemical oxidative polymerization. This polymer was used as a functional conducting polymer intermediate because of its side‐group reactivity. To synthesize the alkyl‐substituted copolymer, the initial copolymer was reacted with NaH to obtain the N‐ and O‐anionic copolymer after the reaction with octadecyl bromide to prepare the octadecyl‐substituted polymer. The microstructure of the obtained polymers was characterized by Fourier transform infrared spectroscopy, 1H‐NMR, and X‐ray diffraction. The thermal behavior of the polymers was investigated by thermogravimetric analysis and differential scanning calorimetry. The morphology of obtained copolymers was studied by scanning electron microscopy. The cyclic voltammetry investigation showed the electroactivity of poly [aniline‐coN‐(2‐hydroxyethyl) aniline] and N and O‐alkylated poly[aniline‐coN‐(2‐hydroxyethyl) aniline]. The conductivities of the polymers were 5 × 10?5 S/cm for poly[aniline‐coN‐(2‐hydroxyethyl) aniline] and 5 ×10?7 S/cm for the octadecyl‐substituted copolymer. The conductivity measurements were performed with a four‐point probe method. The solubility of the initial copolymer in common organic solvents such as N‐methyl‐2‐pyrrolidone and dimethylformamide was greater than polyaniline. The alkylated copolymer was mainly soluble in nonpolar solvents such as n‐hexane and cyclohexane. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012  相似文献   

15.
Poly(N‐[4‐(N′‐phenyl amino carbonyl)phenyl]maleimide), poly(PhPM), has been investigated for the inhibition of the thermal degradation of rigid poly(vinyl chloride) (PVC) in air, at 180°C. Its stabilizing efficiency was evaluated by measuring the length of the induction period, the period during which no detectable amounts of hydrogen chloride gas could be observed, and also from the rate of dehydrochlorination as measured by continuous potentiometric determination, and the extent of discoloration of the degraded polymer. The results have proved the greater stabilizing efficiency of poly(PhPM) relative to that of the DBLC commercial stabilizer. This is well demonstrated by the longer induction period values and by the lower rates both of dehydrochlorination and discoloration of the polymer during degradation relative to those of the DBLC reference stabilizer. The greater stabilizing efficiency of the poly(PhPM) is most probably attributed not only to its possession of various centers of reactivity that can act as traps for radical species resulting during the degradation process, and replacement of labile chlorine atoms on PVC chains by relatively more thermally stable poly(PhPM) moieties, but also due to the ability of its fragmentation products to react with the evolved hydrogen chloride gas. A radical mechanism is suggested to account for the stabilizing action of this polymeric stabilizer. A synergistic effect is achieved when the poly(PhPM) was blended in various weight ratios with DBLC. This synergism attains its maximum when poly(PhPM) and DBLC are taken at 3 : 1 weight ratio. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010  相似文献   

16.
Caesarweed fiber, Urena lobata, was modified by successive treatment with sodium hydroxide and allylchloride in diethylether to yield an average degree of substitution of 2.73 allyl moieties per anhydroglucose unit. The presence of allyl moieties on the fiber was confirmed by infrared spectroscopy. Graft copolymerization of acrylonitrile onto the unmodified and allyl‐modified fibers was initiated by potassium permanganate –N,N′‐dimethylacetamide redox pair in aqueous medium. The allyl fiber was markedly less reactive than the unmodified fiber with graft yields for the latter a factor of 2.3 higher than those of the former. This was attributed to resonance stabilization of allylic macroradicals of the fiber. The graft yield showed positive dependence on N,N′‐dimethylacetamide concentration in the range, 9.0–45.0 × 10?4M with Pg/Pgo of up to 1.39 at the highest concentration. The conversion in graft yield was however characterized by a plateau at the latter concentration and was ascribed to termination of grafted polymer chains by methylacetylaminomethyl radical initiating species. Spectroscopic evidence in support of the latter was the absorption peak at 1680 cm?1 for the graft copolymers, characteristic of C?O stretching vibration for tertiary amide. Acetic acid, at concentrations in the range 0.28–2.22M, was inimical to grafting of acrylonitrile onto allylfibre with Pg/Pgo, of less than one. Grafting onto allylfiber showed positive temperature dependence in the range, 30–50°C with calculated activation energy of 12.3 kcal mol?1 for the graft polymerization reaction. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008  相似文献   

17.
Functionalized polymer membranes have been used as sensor materials for fabrication of electronic tongue. Here, we report the synthesis and characterization of a novel poly(N‐[4H‐1,2,4‐triazol‐4‐yl]acrylamide) (PNTA) for liquid phase aliphatic alcohol sensing in the form of membranes prepared after blending with poly(vinyl chloride) (PVC). Three PNTA‐PVC based membranes were prepared for sensing of six aliphatic alcohols. Polymer membranes were characterized by spectroscopic techniques. Polar groups on PNTA molecules contribute to the alcohol sensing characteristics. The membrane electric potential, generated by the interaction between membrane surface and aqueous aliphatic alcohols, was monitored with the developed multi‐channel electrode based prototype sensing system (MEBPSS). The polymer membranes showed distinct and repeatable response patterns toward different aliphatic alcohols. Among them PNTA‐PVC12 membrane showed maximum discrimination ability due to the PNTA molecules on the membrane surface with highest charge density as ascertained from field emission scanning electron microscopic studies. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44675.  相似文献   

18.
A water‐soluble statistical poly(N‐acryloylmorpholine‐coN‐acryloxysuccinimide) [poly(NAM/NAS)] copolymer was studied for polymer–oligonucleotide (ODN) conjugate elaboration and for further use in diagnostic applications. Three different copolymers were first prepared by free‐radical solution polymerization with different N‐acryloylmorpholine (NAM) and N‐acryloxysuccinimide (NAS) molar ratios (80/20, 70/30, and 60/40). Their number‐average molecular weights ranged from 98,000 to 120,000 g/mol, as determined by aqueous size exclusion chromatography with an online light‐scattering detector. Then, polymer–ODN conjugates were obtained via a strategy consisting of the direct synthesis of ODNs onto polymer chains previously grafted onto a controlled pore glass support. Before the grafting of the polymer onto the solid support, a preliminary step was performed to bind a nucleotide starter along the polymer chain (via the reactive NAS units) to initiate automated DNA synthesis. To multiply the number of ODNs growing from starters, a branched phosphoramidite synthon [bearing two O‐dimethoxytrityl groups] was introduced at the first step of ODN elongation as a short sequence of four branched synthons alternated with three thymidine residues. Conjugates were assessed in a DNA sandwich hybridization test developed for hepatitis B virus detection. Sensitivity limits were evaluated and compared to those obtained with an other polymer, poly(maleic anhydride‐alt‐methyl vinyl ether) [poly(MA/MVE)]. A sensitivity limit of 2.6 × 107 DNA copies/mL was reached with the poly(MA/MVE)–ODN conjugate at the capture phase and with the poly(NAM/NAS)–branched ODN conjugate at the detection phase of the test. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 3784–3795, 2004  相似文献   

19.
Terpolymers based on N‐isopropylacrylamide, sodium 2‐acrylamido‐2‐methyl‐propanesulfonate, and Ntert‐butylacrylamide were synthesized by free‐radical copolymerization with 2,2′‐azobisisobutyronitrile as an initiator. The lower critical solution temperatures (LCSTs) of the linear polymer aqueous solutions were determined by the measurement of the transmittance on UV at different temperatures. The influence of the polymer concentration, polymer composition, and ionic strength on the LCSTs of the linear polymers was investigated. The LCST decreased with increases in the hydrophobic monomer Ntert‐butylacrylamide, polymer concentration, and ionic strength. The phase transition became sharp when the polymer concentration and ionic strength increased. Meanwhile, the crosslinked hydrogels were prepared with the same recipe used for the linear terpolymers, but a crosslinker was added to the reaction system. The swelling ratios of the hydrogels at various temperatures and salt solutions were determined. The hydrogels possessed both high swelling ratios and thermosensitivity. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007  相似文献   

20.
Semi‐1 and semi‐2 interpenetrating polymer networks (IPNs) of poly(vinyl chloride) (PVC) and in situ formed poly(butyl methacrylate) (PBMA) have been synthesized using diallyl phthalate and ethylene glycol dimethacrylate as the crosslinkers of PVC and PBMA, respectively. These were then characterized with reference to their mechanical, thermal, and morphological properties. The mechanical and thermal characteristics revealed modification over the unmodified polymeric systems in relation to their phase morphologies. The semi‐1 IPNs displayed a decrease in their mechanical parameters of modulus and UTS while semi‐2 IPNs exhibited a marginal increase in these two values. The semi‐1 IPNs, however, also revealed a decrease in the elongation and toughness values away from the normal behavior. The thermomechanical behavior of both the systems is in conformity with their mechanicals in displaying the softening characteristics of the system and stabilization over unmodified PVC. The DSC thermograms are also correlated to these observations along with the heterogeneous phase morphology which is displayed by both the systems especially at higher concentration of PBMA incorporation. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008  相似文献   

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