Influence of lanthanum stearate and calcium/zinc stabilizers on stabilization efficiency of dibutyltin dilaurate to polyvinyl chloride

<正>Influences of lanthanum stearate(LaSt_3) and calcium stearate/zinc stearate(Ca/Zn) stabilizers on stabilization efficiency of dibutyltin dilaurate(DBTDL) to polyvinyl chloride(PVC) in air were investigated.The results revealed that the stabilization effect of DBTDL could be achieved by the La/Sn stabilizers with a ratio of 8/2.Addition of DBTDL could enhance thermal property and reduce dynamic storage modulus(G′) at 180℃for PVC containing LaSt_3 or Ca/Zn stabilizers. On the other hand,incorporation of LaSt_3 did not influence the stabilization efficiency of DBTDL markedly;while addition of Ca/Zn stabilizers could significantly decrease thermal property for the DBTDL stabilized PVC.Furthermore,the effects of LaSt_3 and Ca/Zn stabilizers on the stabilization efficiency of DBTDL were explained in the framework of ionization potential.     

Effect of thermal stabilizers composed of zinc barbiturate and calcium stearate for rigid poly(vinyl chloride)

Zinc barbiturate [Zn(H₂L)₂·2H₂O, abbreviated as ZnL₂] was synthesized by a precipitation method in aqueous solution, and investigated as a co-stabilizer with calcium stearate (CaSt₂) for rigid poly(vinyl chloride) (PVC) by the discoloration test and the dehydrochlorination test at 180 °C. ZnL₂ exhibits high stabilizing effect with excellent initial colour of PVC films. In comparison with the synergistic effect of CaSt₂/ZnSt₂ stabilizers, the CaSt₂/ZnL₂ stabilizers in mass ratios ranging from 0.3/1.2 to 0.6/0.9 exhibit better synergistic effect. Moreover, PVC films stabilized by CaSt₂/ZnL₂ show better initial colour with the addition of dibenzoyl methane as an auxiliary stabilizer. The mechanism of stabilizing action of ZnL₂ is also proposed. ZnL₂ may replace the labile chlorine atoms to interrupt the formation of conjugated double bonds in PVC chains, and act as the absorber of hydrogen chloride to restrain the self-catalytic dehydrochlorination.     

Effect of pentaerythritol and organic tin with calcium/zinc stearates on the stabilization of poly(vinyl chloride)

The stabilization effect of calcium and zinc stearates (CaSt₂/ZnSt₂) combined with pentaerythritol (PeE) and organic tin on poly(vinyl chloride) was investigated. The results show that the addition of calcium/zinc stearates combined with PeE and organic tin can improve thermal and colour stability of poly(vinyl chloride) in both static and dynamic tests. Mechanisms for improving stability of PVC are also discussed. The increase of stabilizing effectiveness of calcium/zinc stearates is ascribed to the synergistic effect between CaSt₂/ZnSt₂ and PeE and the interaction between organic tin and double bonds formed during the degradation of PVC. There is no synergistic action between organic tin and PeE or organic tin and calcium/zinc stearates.     

In-bulk formation of a new tetrasubstituted furan from phenolic antioxidants and dibasic lead stearate

The reaction between octadecyl 3-(3,5-di-tert-4-hydroxyphenyl)propanoate and dibasic lead stearate, two compounds added in most PVC formulations, has been investigated in bulk. The structure of the resulting product, obtained after a one-pot synthesis, was characterized by HRMS and 2D NMR analyses. The product of empirical formula C₇₀H₁₁₆O₇ has been identified as an unknown highly substituted furan. The reaction mechanism between both products to produce this original furan has been established. The first step leads to a discoloured lead IV complex with bis-quinonemethide. The second step consist of a hydrolysis during the solvent extractions or under UV exposure leading to a tetrasubstituted furan.     

Synergistic effect of maleimido phenyl urea derivatives mixed with some commercial stabilizers on the efficiency of thermal stabilization of PVC

Four novel antimicrobial maleimido phenyl urea stabilizers 1–4 were synthesized from N-[4-(chlorocarbonyl) phenyl] maleimide with phenyl urea and its derivatives (p-methyl, o-chloro and p-carboxy). The effect of mixing maleimido phenyl urea stabilizer 2 with each of the reference stabilizers, dibasic lead carbonate (DBLC), cadmium-barium-zinc stearate (Cd-Ba-Zn stearate) or n-octyltin mercaptide (n-OTM), on the stabilization efficiency in thermal degradation of rigid PVC at 180 °C in air, has been investigated. Mixing was effected in the range of 0–100 wt% of stabilizer 2 relative to each of the reference stabilizers. The stabilizing efficiency was evaluated by measuring the length of the thermal stability period (Ts), the period during which no detectable amount of hydrogen chloride gas could be observed, and also from the rate of dehydrochlorination as measured by continuous potentiometric determination, and by the extent of discoloration of the degraded polymer samples. The results show a true synergistic effect from the combination of stabilizer 2 with any of the reference stabilizers. Mixing of the stabilizers improves the Ts values, decreases the rate of dehydrochlorination and lowers the extent of discoloration of the polymer. The maximum synergism was attained when stabilizer 2 is mixed with either of the three reference stabilizers in equivalent weight ratio (50%/50%). The observed synergism may be attributed to the different mechanisms by which the investigated and the reference stabilizers work.     

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.     

气相色谱-负化学离子源质谱法测定聚氯乙烯塑料中的短链氯化石蜡

建立了用于聚氯乙烯(PVC)塑料中短链氯化石蜡(SCCPs)含量测定的气相色谱-负化学离子源质谱法。采用超声萃取法对PVC塑料中的SCCPs进行萃取,萃取时间为1.5 h;然后用浓硫酸法对萃取溶液进行净化处理;最后用气相色谱-质谱法在负化学电离模式、离子源温度为160 ℃、甲烷反应气流速为1.5 mL/min等条件下对样品中的SCCPs进行定性定量分析。该方法不受样品中中链氯化石蜡(MCCPs)的干扰,可对样品中的SCCPs进行准确的定量分析。分析的12批次样品均检出SCCPs,含量在0.3×10²~3.5×10⁴mg/kg范围内。依据欧盟对SCCP的限值(1%)要求,4批次样品不符合法规要求,不符合率为33.3%。可见,PVC塑料具有较高的SCCPs污染风险。     

Synergistic effect of combination of Irganox 1010 and zinc stearate on thermal stabilization of electron beam irradiated HDPE/EVA both in hot water and oven

Thermo-oxidative stability of HDPE/EVA blends can be considerably increased by combination of a high-molecular weight phenolic antioxidant and zinc stearate. In this work, the post-irradiation thermal stability of HDPE/EVA blends has been studied. High-density polyethylene and its blends with ethylene-vinylacetate copolymer in both pure form and mixed with Irganox 1010 and zinc stearate were exposed to electron beam radiation at doses between 80 and 150 kGy, at room temperature, in air. In order to evaluate the thermal stability of the samples, post-irradiation heat treatments were done in both hot water bath at 95 °C and in an oven at 140 °C. The mechanical properties and changes in the chemical structure were determined during thermal aging in hot water and oven. The gel content was enhanced by increasing EVA concentration in all applied doses. The stabilized blends have lower gel content than the unstabilized samples. From the results of heat aging treatments it was observed that the thermal stability of the unstabilized blend samples was lower than HDPE. Thermal stability of the samples has been improved by incorporation of Irganox 1010 and zinc stearate. Formation of hydroxyl group was insignificant for stabilized samples during heat aging in both conditions. Also, the changes in the value of oxidation induction time (OIT) for the stabilized samples were negligible after prolonged immersion in hot water.     

Effects of microscale calcium carbonate and nanoscale calcium carbonate on the fusion,thermal, and mechanical characterizations of rigid poly(vinyl chloride)/calcium carbonate composites

A Haake torque rheometer equipped with an internal mixer has been used to study the influence of microscale calcium carbonate (micro‐CaCO₃) and nanoscale calcium carbonate (nano‐CaCO₃) on the fusion, thermal, and mechanical characteristics of rigid poly(vinyl chloride) (PVC)/micro‐CaCO₃ and PVC/nano‐CaCO₃ composites, respectively. The fusion characteristics discussed in this article include the fusion time, fusion temperature, fusion torque, and fusion percolation threshold (FPT). The fusion time, fusion temperature, and FPT of rigid PVC/calcium carbonate (CaCO₃) composites increase with an increase in the addition of micro‐CaCO₃ or nano‐CaCO₃. In contrast, the fusion torque of rigid PVC/CaCO₃ composites decreases with an increase in the addition of micro‐CaCO₃ or nano‐CaCO₃. The results of thermal analysis show that the first thermal degradation onset temperature (T_onset) of rigid PVC/micro‐CaCO₃ is 7.5 °C lower than that of PVC. Meanwhile, the glass‐transition temperature (T_g) of rigid PVC/micro‐CaCO₃ is similar to that of PVC. However, T_onset and T_g of PVC/nano‐CaCO₃ composites can be increased by up to 30 and 4.4%, respectively, via blending with 10 phr nano‐CaCO₃. Mechanical testing results for PVC/micro‐CaCO₃ composites with the addition of 5–15 phr micro‐CaCO₃ and PVC/nano‐CaCO₃ composites with the addition of 5–20 phr nano‐CaCO₃ are better than those of PVC. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 451–460, 2006     

Influence of a mixing solvent with tetrahydrofuran and N,N‐dimethylformamide on electrospun poly(vinyl chloride) nonwoven mats

We evaluated the effects of the solvent composition with respect to the solution concentration, applied electric field, and tip‐to‐collector distance on the morphology of electrospun poly(vinyl chloride) (PVC) fibers. The solvent volume ratio was strongly correlated with the diameter of the electrospun fibers with respect to the other processing parameters. Electrospun PVC fibers dissolved in tetrahydrofuran (THF) had diameters ranging from 500 nm to 6 μm; those dissolved in N,N‐dimethylformamide (DMF) had an average diameter of 200 nm. The diameters of the electrospun fibers were obtained from narrow to broad distributions with the solvent composition. Also, the diameters of fibers electrospun from a mixed solvent of THF and DMF were less than 1 μm. The mechanical properties of electrospun PVC nonwoven mats depended on the fiber orientation and linear velocity of the drum surface. With increasing linear velocity of the drum surface, electrospun PVC fibers were arranged toward the machine direction, and the dimensions of the spiral path were shorter. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 2259–2268, 2002     

Effect of polyaniline as a surface modifier of TiO2 nanoparticles on the properties of polyvinyl chloride/TiO2 nanocomposites

Surface of TiO2 nanoparticles was modified with the in situ chemical oxidative polymerization of aniline. Polyaniline modified TiO2 nanoparticles (PANI-TiO2 ) were characterized with the FT-IR, XRD, SEM and TEM techniques. Results confirmed that PANI was grafted successfully on the surface of TiO2 nanoparticles, therefore agglomeration of nanoparticles decreased dramatically. Polyvinyl chloride nanocomposites filled with 1 wt% 5 wt% of PANI-TiO2 and TiO2 nanoparticles were prepared via the solution blending method. PVC nanocomposites were analyzed with FT-IR, XRD, SEM, TG/DTA, DSC and tensile test techniques. Effect of PANI as surface modifier of nanoparticles was discussed according to the final properties of PVC nanocomposites. Results demonstrated that deposition of PANI on the surface of TiO2 nanoparticles improved the interfacial adhesion between the constituents of nanocomposites, which resulted in better dispersion of nanoparticles in the PVC matrix. Also PVC/PANI-TiO2 nanocomposites showed higher thermal resistance, tensile strength and Young’s modulus compared to those of unfilled PVC and PVC/TiO2 nanocomposites.     

The influence of core-shell structured modifiers on the toughness of poly (vinyl chloride)

The core-shell structured grafted copolymer particles of polybutadiene grafted polymethyl methacrylate (PB-g-PMMA, MB) were prepared by emulsion polymerization. The MB particles were used to modify poly (vinyl chloride) (PVC) by melt blending. The mechanical properties of the PVC blends were investigated. The micro-morphology of the PVC blends was observed by scanning electron microscopy (SEM). The results indicated that the samples with the best impact strength could be obtained when the core-shell weight ratio of PB to PMMA is lower than 93:7, the mechanical properties correlated well with SEM morphologies, the addition of modifier with the ratio core to shell of 93:7 could reduce the domain size of the dispersed phase. Furthermore, the compatibility and properties of the blends were greatly enhanced and improved. The modifier particles could be well dispersed in the PVC matrix.     

Organic thermal stabilizers for rigid poly(vinyl chloride). Part XII: N-phenyl-3-substituted-5-pyrazolone derivatives

N-phenyl-3-substituted-5-pyrazolone derivatives have been examined as thermal stabilizers or co-stabilizers for rigid PVC in air, at 180 °C. Their high stabilizing efficiency is detected by their high induction period values (T_s) when compared with some of the common reference stabilizers used industrially, such as dibasic lead carbonate, calcium-zinc soap and n-octyl tin mercaptide. Blending these derivatives with some of the reference stabilizers in different ratios had a synergistic effect on both the induction period and the dehydrochlorination rate.A probable mechanism for the stabilizing mode of N-phenyl-3-substituted-5-pyrazolone derivatives has been proposed. The stabilizing efficiency is attributed at least partially to the ability of the organic stabilizer to be incorporated in the polymeric chains, thus disrupting the chain degradation.     

Properties of poly(vinyl chloride)/wood flour/montmorillonite composites: Effects of coupling agents and layered silicate

Organomodified montmorillonite (OMMT) was prepared using cetylalkyl trimethyl amine bromide. OMMT and wood flour (WF) were surface-modified by silane coupling agent. They were melt-blended with polyvinyl chloride (PVC) and extruded into wood-plastic composite samples using one conical twin screw extruder. The effects of their contents on the composite mechanical properties were investigated. X-ray diffraction, transmission electron microscopy and scanning electron microscopy observed intercalation and dispersion of the OMMT. FTIR and X-ray photoelectron spectroscopy were used to analyze the silane-modification effects. The possible reaction mechanisms were proposed. After wood flour was modified by 1.5 phr silane, the impact strength and the tensile strength of wood flour-PVC composite were increased by 14.8% and 18.5%, respectively. Mechanical tests showed that the addition of OMMT did not enhance the untreated wood flour-PVC composites. However, adding 0.5% OMMT did improve the mechanical properties of the treated ones. The grafting improved the interfacial compatibility between components producing higher properties of the composites. Further addition of OMMT reinforced the composites. Too higher contents of silane and OMMT impaired some properties because of weak interfacial layer and higher concentrated stress. Cone calorimetry showed that the fire flame retardancy and smoke suppression of composites were strongly improved with the addition of OMMT.     

Ring‐opening metathesis polymerization as a route to controlled copolymers of ethylene and polar monomers: Synthesis of ethylene–vinyl chloride‐like copolymers

A series of ethylene–vinyl chloride‐like copolymers were prepared by ring‐opening metathesis polymerization (ROMP). The route to these materials included the bulk polymerization of 5‐chlorocyclooctene and 5,6‐dichlorocyclooctene with the first‐generation Grubbs' catalyst, followed by diimide hydrogenation of the resulting unsaturated polymers. In addition, the amount of chlorine in these materials was varied by the copolymerization of 5‐chlorocyclooctene with cyclooctene. These materials were fully characterized by NMR (¹H and ¹³C), gel permeation chromatography, and Fourier transform infrared spectroscopy. Finally, hydroboration was carried out on the ROMP product of 5‐chlorocyclooctene to yield a polymer, which was effectively a vinyl alcohol–vinyl chloride–ethylene terpolymer. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 2107–2116, 2003     

Dechlorination of poly(vinylidene chloride) in NaOH/ethylene glycol as a function of NaOH concentration, temperature, and solvent

The wet dechlorination treatment of poly(vinylidene chloride) (PVDC) was evaluated at atmospheric pressure in a solution of NaOH in ethylene glycol (EG), as a function of NaOH concentration, temperature, and solvent. Hydroxide ion from NaOH was required for dechlorination with EG acting solely as a solvent. The wet treatment exhibited significantly enhanced dechlorination efficiency over traditional thermal techniques, with a reaction efficiency as high as 92.8% in 1.0 M NaOH at 190 °C. Dechlorination reactions of PVDC in both NaOH/EG and NaOH/H₂O were expressed by an apparent first-order reaction. At 190 °C, the apparent rate constant in 1.0 M NaOH/EG was approximately 1.4 times larger than in 1.0 M NaOH/H₂O, with an apparent activation energy of 82.8 kJ mol⁻¹, indicating that the reaction proceeded under chemical control. The degree of dechlorination increased with increasing reaction temperature, favouring the elimination of HCl over the hydroxyl substitution of chloride.     

Carboxylated graphene oxide/polyvinyl chloride as solid-phase extraction sorbent combined with ion chromatography for the determination of sulfonamides in cosmetics

A carboxylated graphene oxide/polyvinyl chloride (CGO/PVC) material was prepared as a sorbent for the selective extraction of sulphonamides from complex sample. After being dispersed in buffer solution, sample was transferred into the prefabricated solid-phase extraction (SPE) column, which integrated extraction and cleanup into one single-step. A multi-response optimization based on the Box-Behnken design was used to optimize factors affecting extraction efficiency. Compared with the commonly commercial sorbents including MCX, WCX and C₁₈, CGO/PVC hybrid material had higher extraction selectivity and capacity to sulphonamides. The limits of detection and quantification for seven target compounds were in the range of 3.4–7.1 μg/L and 11.4–23.7 μg/L, respectively. The self-assembly SPE cartridge was successfully used to enrich seven analytes in anti-acne cosmetics prior to ion chromatography detection with good recoveries of 87.8–102.0% and relative standard deviations of 1.2–6.4%, implying that this method was suitable for routine analysis of cosmetics.     

Local chain‐configuration dependence of the mechanisms of the chemical reaction of poly(vinyl chloride). IX. Novel results on stereoselectivity of chlorination reaction

A poly(vinyl chloride) (PVC) sample was chlorinated in solution in the presence of 2,2′‐azobisisobutyronitrile and by the fluid‐bed method. The aim was to evaluate the scope of the stereoselectivity of the chlorination reaction. The quantitative microstructural analysis of the residual PVC with a degree of chlorination was followed by ¹³C NMR spectroscopy. From the evolution of the content of isotactic (mm), heterotactic (mr), and syndiotactic (rr) triads and of mmmm, mmmr, and rmmr isotactic pentads in the unchlorinated parts of the polymer, it was unambiguously inferred that the chlorination reaction proceeds by a stereoselective mechanism in that the mr heterotactic triads are the most reactive structures followed by the isotactic triad at mmmr and rmmr pentads. This conclusion was confirmed on the basis of the Fourier transform infrared results. The results provide valuable information regarding the effect of tacticity and related local conformations in the chemical reactions of PVC. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 508–519, 2003     

The compatibility of (natural) polyols with heavy metal- and zinc-free poly(vinyl chloride): Their effect on rheology and implications for plate-out

This paper describes the rheological effects observed after addition of (natural) polyols to several different types of heavy metal-free PVC formulations. It is found that addition of natural polyols, such as sorbitol, leads to changes in the rheology of the system comparable to the addition of external lubricants. Hence as suggested previously, addition of (natural) polyols may lead to the occurrence of undesirable plate-out phenomena. The magnitude of the effect on the rheology depends on the number of hydroxyl groups in the polyol and its propensity to undergo intramolecular cyclodehydration reactions. It is established that the undesirable rheological effects, which coincide with plate-out phenomena, can be suppressed by the addition of various types of inorganic as well as organic substances, most of which are known PVC additives. This will allow for the use of (natural) polyols as efficient and benign co-stabilisers in next generation stabiliser systems.     

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.