Antimicrobial agents as photostabilizers for rigid poly(vinyl chloride)

Some amide derivatives of ethylene glycol‐bis(2‐aminoethylether)‐N,N,N^′,N^′‐tetraacetic acid (EGTA) have been prepared via their coupling with different aniline derivatives: amino, methyl, chloro, and hydroxy aniline. The EGTA amide derivatives were characterized, and their antimicrobial activities were evaluated. These antimicrobial agents have been investigated as photostabilizers for rigid poly(vinyl chloride) (PVC), suspension PVC, with a K value of 70. Their stabilizing efficiencies were evaluated by determining the percentage of weight loss, the intrinsic viscosities, as well as the amount of formed gel of the photodegraded PVC. The extent of discoloration and the change in the mechanical properties of the photodegraded polymer were also evaluated. The applied materials reduced the loss in weight that resulted from HCl evolution during photodegradation. Both viscosity and gel content measurements showed also a decrease in their values during the degradation process. The decrease in the percentage of gel formation upon applying the investigated photostabilizers reflects the lowering in extent of cross‐linking of the polymer, which implies preserving the mechanical properties of PVC. The extent of discoloration was also improved in the presence of the investigated compounds. The results have proved a greater stabilizing efficiencies of the antimicrobial EGTA amide derivatives than that of the phenyl salicylate ultraviolet (UV) absorber, which is commonly used as an industrial stabilizer. A radical mechanism was proposed to account for the stabilizing action of the investigated products. Copyright © 2011 John Wiley & Sons, Ltd.     

Anthraquinone derivatives as organic stabilizers for rigid poly(vinyl chloride) against photo-degradation

Anthraquinone derivatives have been prepared and investigated as photo-stabilizers for rigid PVC by measuring the extent of weight loss (%), the amount of gel formation as well as the intrinsic viscosity of the soluble fractions of the degraded polymer. The results indicated a reasonable stabilizing effect of these derivatives compared with UV-commercially used stabilizers. A synergistic effect is achieved when the anthraquinone derivatives are mixed with UV-absorbers in a weight ratio of 75% of investigated organic stabilizer and 25% of reference stabilizer.A probable radical mechanism is proposed to account for the stabilizing action of the organic investigated materials.     

Thermal and mechanical behaviour of flexible poly(vinyl chloride) mixed with some saturated polyesters

Four saturated polyesters poly(hexamethylene adipate), poly(ethylene adipate), poly(hexamethylene terephthalate) and poly(ethylene terephthalate) were prepared. The resulting materials were characterized by IR and ¹H NMR, end group analysis and gel permeation chromatography. The effect of blending these polyesters (5 and 10%) with poly(vinyl chloride) (PVC) in the melt was investigated in terms of changes in the thermal behaviour of PVC by studying the weight loss after 50 min at 180 °C, colour changes of the blend before and after aging for one week at 90 °C, the variation in glass transition temperature and the initial decomposition temperature. The results gave proof for the stabilizing role played by the investigated polyesters against the thermal degradation of PVC. The best results are obtained when PVC is mixed with 5% aliphatic polyesters rather than with aromatic ones. This is well illustrated not only from the increase in the initial decomposition temperature (IDT), but also from the decrease of % weight loss and from the lower extent of discolouration of PVC, which is a demand for the application of the polymer. It was also found that blending PVC with 5% of the four investigated polyesters before and after aging for one week at 90 °C gave better mechanical properties even than that of the unaged PVC blank.     

N-(Substituted phenyl) itaconimides as organic stabilizers for plasticized poly(vinyl chloride) against photo-degradation

Several N-(substituted phenyl)itaconimide derivatives, N-(RPh)II (R: -NO₂, -COOH, -H, -OH, -OMe, -Me, -Cl, or -Br), have been investigated as organic photo-stabilizers for poly(vinyl chloride) (PVC) plasticized with dioctyl phthalate (DOP). Their stabilizing efficiencies are evaluated by measuring the length of the induction period (Ts), 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 discolouration of the degraded polymer. The efficiencies are also evaluated by determining the amount of gel formation as well as the intrinsic viscosity of the insoluble and the soluble fractions of the degraded polymer, respectively. The results have proved the greater stabilizing efficiency of the N-(RPh)II derivatives relative to that of the phenyl salicylate UV absorber which is a commonly used industrial stabilizer. A radical mechanism is proposed to account for the stabilizing action of the investigated products.     

聚氯乙烯的热可逆共价交联

利用环戊二烯 (CPD)在常温下自动二聚形成双环戊二烯 (DCPD)、在高温下DCPD又可解聚成CDD的热可逆Diels Alder反应 ,合成了DCPD二羧酸衍生物 ,并将其引作聚氯乙烯 (PVC)的共价交联 ,研究了交联剂种类和用量对交联程度、力学性能和流动特性的影响及交联产物的热可逆转化行为 ,制得了力学性能和耐热性均有所提高的热可逆共价交联PVC     

Vanillin–Schiff’s bases as organic thermal stabilizers and co-stabilizers for rigid poly(vinyl chloride)

Vanillin–Schiff’s bases (VSB) were examined as thermal stabilizers and co-stabilizers for rigid poly(vinyl chloride) (PVC) in air at 180 °C. Their high stabilizing efficiency were shown by their high thermal stability value (Ts), which is the time elapsed for the detection of HCl gas, if compared with dibasic lead carbonate and cadmium–zinc soap reference stabilizers used industrially, with better extent of discoloration. Blending these derivatives with reference stabilizers in different ratios greatly lengthens the thermal stability and the extent of discoloration of the PVC.Condensation products of Vanillin with amines are very active biologically, besides having good complexation ability with metal ions. The Ni²⁺ and Co²⁺ complexes of VSB derivatives gave better thermal stability and less discoloration than the parent organic stabilizer. Also, blending these complexes with either of the used reference stabilizers in different ratios gave better thermal stability and lower extent of discoloration. Thermogravimetric analysis confirmed the improved stability of PVC in the presence of the VSB derivatives, compared to blank PVC, PVC stabilized with reference stabilizers and PVC stabilized with binary mixture of VSB derivatives with reference stabilizer.The stabilizing efficiency of Vanillin–Schiff’s base (VSB) derivatives is attributed to the replacement of the labile chlorine atoms on the PVC chains by a relatively more stable moiety of the organic stabilizer.     

Effect of solvent type on formation of PVC‐solvent complex

The effect of solvent type on the structural features of PVC gels prepared from the solutions of dibutyl phthalate(DBP) and butyl benzoate(BB) were investigated. The influence of solvent type, i.e., diester solvent or monoester solvent, on the mechanical responses was characterized by dynamic viscoelastic measurements as a function of temperature, aging time, and PVC concentration. In the case of PVC/DBP aged gels, the transition phenomenon appeared close to 50°C, whereas no such transitions were observed for PVC/BB aged gels. This transition is considered to be associated with polymer‐solvent complex which can be accounted for electrostatic interaction between C=O bond of solvent and H‐C‐Cl part of PVC. While BB solvent molecules can not form polymer‐solvent complex due to no capacity to act as a bridge between PVC molecular chains. FT‐IR spectroscopy and DSC investigation on either PVC/DBP gels or PVC/BB gels was reported and discussed together with the mechanical behavior. Electron micrographs of the dried gel prepared from the critical point drying technique reveal that the gel morphology consists of well developed three dimensional fibrous network structure independent of solvent type.     

Comprehensive study on reinforcement of poly(vinyl chloride) nanocomposite films with ZnO nanoparticles modified by citric acid and vitamin C

We reported a general facile approach for modifying NPs and incorporating them into PVC polymer via ultrasonic irradiation. ZnO nanoparticles (NP)s modified with ascorbic acid (AS) and citric acid (CA) were employed to investigate the agglomeration behavior under poly(vinyl chloride) PVC matrix. To compare and determine the suitable construction, the prepared PVC/ZnO-CA-AS NCs (4, 8, 12?wt%) were characterized. UV-visible measurements indicate, increasing absorption value results in an increase of ZnO content. According to the obtained information from the TGA of the NCs, further increases in modified ZnO results in an increase in flame-retardancy. The mechanical properties investigation revealed improvement of the elongation at maximum stress.     

Rheology of asphalts modified with glycidylmethacrylate functionalized polymers

Asphalt is known to be a colloidal suspension in which asphaltenes are covered by a stabilizing phase of polar resins and form complex micelles that are dispersed in the oily maltenic phase. In order to enhance its mechanical properties (e.g., in road paving), asphalts are often loaded with polymeric materials, thereby obtaining blends that can have different physical or chemical structures, depending on the composition of the added polymer. Asphalts modified by the addition of reactive ethylene terpolymers were prepared and their dielectric and rheological properties were measured both before and after a cure at high temperature. Even if it is not possible to determine the exact nature of the chemical interactions between asphalt and polymer, master curves obtained from dynamic data clearly show that during the cure the material tends to the behavior of a cross-linked network.     

Viscoelastic and thermal characterization of crosslinked PVC

Soft PVC is employed for the manufacturing of a wide range of products with different properties and a relatively low cost. The utilization of soft PVC is restricted by the poor thermal, chemical and mechanical resistance properties. Also, plasticizer migration can modify the properties or can make useless the materials for some applications because of toxicity or a general loss of properties. PVC crosslinking is the most effective way to improve mechanical and transport properties of rigid or flexible PVC at high temperatures, but at the same time the thermal stability of PVC may be significantly reduced. In this work, the crosslinking reaction of plasticized poly(vinyl chloride) (PVC) through difunctional amines was studied. The mechanisms involved in the crosslinking reaction were explained by Fourier transform infrared (FTIR) analysis. The thermal activated crosslinking reaction was studied by cone and plate rheometry, analyzing the evolution of viscoelastic properties of the suspension as a function of time and temperature. The effect of the addition of crosslinking agents on the thermal stability of the polymer was studied by thermogravimetric analysis (TGA), which revealed that crosslinking reactions promote thermal degradation phenomena in the polymer matrix. This is attributed to the formation of HCl and other species promoting polymer degradation during crosslinking, thus leading to higher weight loss during thermal treatment with respect to unmodified PVC plastisols. This was also confirmed by an evident yellowing after crosslinking, especially at higher temperatures.     

Shape memory polymer based on chemically cross-linked poly(vinyl alcohol) containing a small number of water molecules

In this paper, shape memory polymers based on poly(vinyl alcohol) (SM-PVA) cross-linked with different contents of glutaraldehyde were prepared. Because PVA is a hydrophilic polymer, all samples prepared always have a small number of water molecules exposed to air, and the water molecules are helpful for shape memory characteristics. The influences of water contents on the prepared materials were investigated. The properties of SM-PVA were investigated by dynamic–mechanical analysis, differential scanning calorimetry, and thermogravimetric analysis. Shape memory behavior of SM-PVA, depending on the switching of chain segments, occurred at around T _g. Thermo-mechanical cycle test was performed to investigate shape memory properties, including the percentage shape recovery, shape recovery ratio, and percentage shape fixity. The studied materials show promising shape memory and cyclic behavior indicative of potential applications of SM-PVA as shape memory materials.     

Effects of ceramic filler in poly(vinyl chloride)/poly(ethyl methacrylate) based polymer blend electrolytes

Effects of nano-ceramic filler titanium oxide (TiO₂) have been investigated on the ionic conductance of polymeric complexes consisting of poly(vinyl chloride) (PVC)/poly(ethyl methacrylate) (PEMA), and lithium perchlorate (LiClO₄). The composite polymer blend electrolytes were prepared by solvent casting technique. The TiO₂ nanofillers were homogeneously dispersed in the polymer electrolyte matrix and exhibited excellent interconnection with PVC/PEMA/PC/LiClO₄ polymer electrolyte. The addition of TiO₂ nanofillers improved the ionic conductivity of the polymer electrolyte to some extent when the content of TiO₂ is 15 wt%. The addition of TiO₂ also enhanced the thermal stability of the electrolyte. The changes in the structural and complex formation properties of the materials are studied by X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) techniques. The scanning electronmicroscope image of nano-composite polymer electrolyte membrane confirms that the TiO₂ nanoparticles were distributed uniformly in the polymer matrix.     

Improving mechanical and electrical properties of poly(vinyl alcohol-<Emphasis Type="Italic">g</Emphasis>-acrylic acid) nanocomposite films by reinforcement of thermally reduced graphene oxide

Graphene has drawn an astounding research interest in recent years, owing to its exceptional properties. The scaled-up and trustworthy production of graphene derivatives, such as graphene oxide (GO) and thermally reduced graphene oxide (TRGO), offer wide variety of possibilities to synthesize graphene-based polymer materials for various applications. In the present work, poly(vinyl alcohol-g-acrylic acid) films were prepared by grafting polyacrylic acid chains onto polyvinyl alcohol backbone employing a free radical polymerization system in the presence of crosslinking agent, N,N′-methylenebisacrylamide (MBA). The graphene was homogeneously dispersed into the prepared polymer using thermal mechanical agitation technique. The so prepared nanocomposites were undertaken for structural and morphological characterization using FTIR, SEM, XRD, Raman Spectroscopy, DLS, Zetasizer and AFM analysis, respectively. The electrical conductive and mechanical properties of prepared nanocomposite films were also investigated.     

N-(Substituted phenyl)itaconimide-phenyl salicylate blends as organic stabilizers for plasticized poly(vinyl chloride) against photo-degradation

The effect of blending some N-(substituted phenyl)itaconimide derivatives, N-(RPh)II, (R: -H, or -OMe) with phenyl salicylate UV absorber on the stabilizing efficiency in photo-degradation of PVC plasticized with dioctyl phthalate (DOP) has been investigated. Blending was effected in the range of 0-100 wt% of the itaconimide relative to reference stabilizer. The stabilizing efficiency was evaluated by measuring the length of the induction period (Ts), 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 on one hand, and the extent of discoloration of the degraded polymer on the other. The efficiencies are also evaluated by determining the amount of gel formation as well as the intrinsic viscosity of the insoluble and the soluble fractions of the degraded polymer. The results show a true synergistic effect from the blending of itaconimide derivative with phenyl salicylate UV absorber. Blending of the stabilizers improves the Ts values, decreases the rate of dehydrochlorination, and lowers the extent of discoloration and the gel content of the polymer. The synergism attains its maximum when both the itaconimide and the reference stabilizers are taken in equimolar ratios. The observed synergism may be attributed to the combination of mechanisms by which the itaconimide and the reference stabilizer work.     

Thermal and dynamic mechanical behavior of polyurethanes based on diisocyanates and diethanolamine derivatives with mesogenic groups in side chain

Thermotropic polyurethanes were prepared from three commercial diisocyanates of various flexibility and eight diols (based on diethanolamine derivatives) with mesogenic groups in side chain with stoichiometric ratio of reactive isocyanate and hydroxy groups. Polymers were studied by dynamic mechanical spectroscopy, X-ray scattering, differential scanning calorimetry and polarizing microscopy. The effect of structure changes in the diisocyanates and diols, in particular changes in the end substituents bound to the mesogen, were investigated. Introduction of mesogenic diols into the polymers suppresses the occurrence of mesophases in comparison with neat diols; in the case of simple end substituents (such as hydrogen, nitro and nitrile), the mesophases disappear completely regardless of the structure of diisocyanate. Stiff end substituents (phenyl and alkoxy groups) stabilize the mesophases to such an extent that the negative influence of long polymer chains is compensated and the liquid-crystalline (LC) properties are recovered. Generally, the polymers prepared from the stiffest 2(4)-methyl-1,3-phenylene diisocyanate exhibit a most pronounced LC behavior.     

Novel antimicrobial and antitumor organic thermal stabilizers for rigid Poly (vinyl chloride)

Pyrazolodithiones of expected biological activity were examined as thermal stabilizers and co-stabilizers for rigid poly(vinyl chloride) (PVC) in air at 180?°C. Their high stabilizing efficiency were shown by their high thermal stability values (T _s), which is the time needed for the liberation of HCl gas, if compared with dibasic lead carbonate (DBLC) and calcium?Czinc soap (Ca?CZn soap) reference stabilizers used industrially, with better extent of discoloration. Blending these derivatives with reference stabilizers in different ratios greatly lengthens the thermal stability value and improves the extent of discoloration of the PVC. The structure of the novel organic stabilizers was confirmed by elemental analysis, FTIR, Mass spectra, and ¹H-NMR. Thermogravimetric analyses confirmed the improved stability of PVC in the presence of the investigated organic stabilizers, compared to blank PVC and PVC stabilized with the reference stabilizers. Also, GPC measurements were done to investigate the changes occurred in the molecular masses of the degraded samples of PVC in presence of the newly synthesized stabilizers. The stabilizing efficiency of pyrazolodithiones is attributed to the replacement of the labile chlorine atoms on the PVC chains by a relatively more stable moiety of the organic stabilizer. The investigated stabilizers showed a good antimicrobial activity toward two kinds of bacteria, Escherichia coli and Staphylococcus aureus; and also toward two kinds of fungi, Aspergillus flavus and Candida albicans. They also exhibited antitumor activity against both liver and colon human cell lines.     

聚氯乙烯/纳米水滑石复合材料的形态与力学性能

对由原位悬浮聚合制备的聚氯乙烯(PVC)纳米水滑石复合树脂加工得到的纳米复合材料的形态和力学性能进行了研究,并与直接熔融加工得到的PVC纳米水滑石复合材料进行比较.发现由前一方法得到的PVC纳米水滑石复合材料中纳米水滑石的分散性明显优于由后一方法得到的PVC纳米水滑石复合材料,水滑石以初级粒子形式存在,分散良好,无明显团聚体;与之对应,由前一方法得到的PVC纳米水滑石复合材料的力学性能也明显优于由后一方法得到的PVC纳米水滑石复合材料,当纳米水滑石含量小于5wt%时,复合材料的杨氏摸量、拉伸强度和缺口冲击强度均随水滑石含量增加而增大;纳米水滑石的引入可显著提高复合树脂的热稳定性;PVC纳米水滑石复合材料的储能和损耗模量略大于纯PVC材料,而损耗因子和玻璃化温度变化不大.     

Morphology and fracture behavior of toughening‐modified poly(vinyl chloride)/organophilic montmorillonite composites

Toughening‐modified poly(vinyl chloride) (PVC)/organophilic montmorillonite (OMMT) composites with an impact‐modifier resin (Blendex 338) were prepared by melt intercalation, and their microstructures were investigated with wide‐angle X‐ray diffraction, transmission electron microscopy, and scanning electron microscopy. The mechanical properties of the PVC composites were examined in terms of the content of Blendex and OMMT, and the fracture toughness was analyzed with a modified essential work of fracture model. Intercalated structures were found in the PVC/OMMT composites with or without Blendex. Either Blendex or OMMT could improve the elongation at break and notched impact strength of PVC at proper contents. With the addition of 30 phr or more of Blendex, supertough behavior was observed for PVC/Blendex blends, and their notched impact strength was increased more than 3319% compared with that of pristine PVC. Furthermore, the addition of OMMT greatly improved both the toughness and strength of PVC/Blendex blends, and the toughening effect of OMMT on PVC/Blendex blends was much larger than that on pristine PVC. Blendex and OMMT synergistically improved the mechanical properties of PVC. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 286–295, 2004     

Novel poly(vinyl chloride) based thermoplastic elastomers incorporating vinyl-functionalized silicone rubber

ABSTRACT

Novel poly(vinyl chloride) (PVC) based thermoplastic elastomers were developed by blending with different proportions of vinyl-functionalized silicone rubber. Scanning electron microscopy (SEM) confirmed good compatibility between PVC and silicone rubber which allowed enhancement of the stress-strain behavior. On the contrary to neat PVC, exposure to heat or UV radiation was found not to cause any considerable deterioration to the stress-strain behavior. Fourier Transform Infrared (FTIR) revealed a possible chemical interaction between the blend components involving the vinyl groups from the silicone rubber, which is thought to be the reason for maintaining the mechanical properties unaltered. Further investigation with ultraviolet-visible (UV-Vis.) spectroscopy signified absence of intensive dehydrochlorination usually encountered for PVC after exposure to heat or UV radiation, which indicates a potential stabilizing effect for the silicone rubber and build up of a network structure comprising both hard and soft segments.     

4-Nitrophthalic esters as plasticizers for polyvinyl chloride

The properties of polyvinyl chloride (PVC) compositions plasticized with dibutyl and di-(2-ethylhexyl)esters of phthalic and 4-nitrophthalic acids were investigated. The result of physical and mechanical tests and dynamic mechanical analysis of samples of polymer compositions demonstrated that an introduction of a nitro group and an increase in the polarity of the plasticizer leads to a decrease in its volatility from polymer films, an increase in the strength and elasticity of the samples. Quantum-chemical calculations of systems simulating polymer-plasticizer solvation interactions revealed the possibility of enhancing intermolecular interactions with the participation of nitrophthalates. It is noted that the method of PVC film formation (from solutions or from melts) affects their properties.