Effect of zinc maleate/zinc oxide complex on thermal stability of poly(vinyl chloride)

In this study, zinc maleate (ZnMA) and zinc oxide (ZnO) complex (ZnMA/ZnO) was prepared by two methods, namely, by the reaction of maleic acid (MAH) with excess ZnO in aqueous solution and by direct mixing of ZnMA and ZnO at 180°C. The chemical structure of the complex was analyzed by X‐ray diffraction, thermogravimetric analysis (TGA), and Fourier transform infrared (FTIR) spectroscopy. The thermal stabilizing effect of the complex on poly(vinyl chloride) (PVC) was evaluated through static and dynamic stability methods. Compared to calcium and zinc soaps and ZnMA alone, the complex exhibited better thermal stabilizing effect on PVC. The stabilization mechanism was also investigated by ultraviolet–visible spectrometer, FTIR, TGA, and gel content analysis. The results indicated that the complex which involved the replacement of labile chlorine atoms hindered the formation of conjugated double bonds in PVC chains via Diels–Alder reaction, and ZnMA/ZnO complex also exhibited the ability to absorb hydrogen chloride. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41464.     

The effect of pentaerythritol‐aluminum on the thermal stability of rigid poly(vinyl chloride)

Pentaerythritol‐aluminum (PE‐Al) was synthesized by a solid‐phase reaction in this study. The formation and characteristics of PE‐Al were confirmed by scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). SEM images showed that the shapes of PE‐Al particles were spherical and the average size was around 23 nm. The thermal properties of rigid poly(vinyl chloride) (PVC) with PE‐Al were tested by Congo red test, thermal aging test, conductivity test, thermogravimetric analysis (TGA), and UV–visible spectroscopy test. The results showed that combination of PE‐Al, in comparison with commercial thermal stabilizers, presented an obvious improvement in stabilization efficiency of PVC. Moreover, addition of PE‐Al could significantly prolong static stability time of PVC, reduce weight loss, and improve the initial color of PVC films. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 3704–3709, 2013     

Thermal stability of poly(vinyl chloride)/layered double hydroxide nanocomposites

Effects of nanoscale dispersed layered double hydroxides (LDHs) on thermal stability of poly(vinyl chloride) (PVC) in thermal and thermooxidative degradation processes are investigated by dynamic and isothermal thermogravimetric analysis (TGA), discoloration test, fourier transform infrared (FTIR), and ultraviolet‐visible (UV‐vis) spectroscopic techniques. During both stages of thermal degradation, the degradation temperatures, including onset degradation temperature and temperature of the maximum degradation rate, increase, and the final residue yield of the PVC/LDH nanocomposites reaches 14.7 wt %, more than double that for neat PVC. The thermooxidative degradation process is more complex. During the first two stages, the presence of nanoscale dispersed LDH particles enhances the thermal stability, whereas in the last stage accelerates the thermal degradation possibly due to the accumulation of heat released. Additionally, the studies of the isothermal thermooxidative degradation process by FTIR and UV‐vis spectra indicate that both polyene backbone formation and some carbonyl groups are simultaneously developed. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Zinc maleate and calcium stearate as a complex thermal stabilizer for poly(vinyl chloride)

Zinc maleate (ZnMA) and calcium maleate (CaMA) were synthesized by reaction of maleic acid with the corresponding metal oxides and were characterized by X‐ray diffraction, thermal analysis, and Fourier‐transform infrared (FTIR) spectroscopy. The thermal stabilizing effects of ZnMA and CaMA on poly(vinyl chloride) (PVC) were investigated at 180°C in air by a static stability test. The stabilization mechanism of ZnMA and the synergism of ZnMA/CaSt₂ (St = stearate) were also studied by UV‐visible and FTIR spectroscopies, as well as a thermal stability test. The PVC with the ZnMA stabilizer exhibited good thermal and color stability caused by the ability of ZnMA to replace the labile chlorine atoms in PVC chains, absorb hydrogen chloride, and react with the polyene intermediates via a Diels–Alder mechanism. The gel content of the PVC/ZnMA samples reached 31% after 2 min of heating and 44% after 10 min, thereby indicating that crosslinking could easily occur with ZnMA, probably owing to catalysis by Zn species. The static and dynamic stability results showed that the synergistic effect of the ZnMA/CaSt₂ stabilizer was greater than that of ZnSt₂/CaSt₂. J. VINYL ADDIT. TECHNOL., 20:1–9, 2014. © 2014 Society of Plastics Engineers     

Chitosan–graphene oxide nanocomposites: Effect of graphene oxide nanosheets and glycerol plasticizer on thermal and mechanical properties

In this study, graphite oxide (GO) is synthesized from natural graphite flakes by the modified Hummers method. Characterization by Fourier transform infrared, X‐ray photoelectron, Raman and ultraviolet‐visible spectroscopies, X‐ray diffraction, and thermogravimetric analysis is conducted on GO to confirm the oxidation of graphite. Unplasticized and glycerol plasticized chitosan/graphene oxide (CS/GO) nanosheets nanocomposites with different GO loadings are prepared by solution casting. The combined effect of GO and glycerol on structure, thermal and mechanical properties of nanocomposite films is studied. GO nanosheets are well dispersed throughout the CS matrix due to the hydrogen bonding and electrostatic interactions between CS and GO nanosheets. The incorporation of GO within the CS matrix results in a decrease of the crystallinity, an improvement of thermal stability, and a significant enhancement of the stiffness and tensile strength that is emphasized by the glycerol. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45092.     

油酸⁃苯甲酸钙/锌液体复合热稳定剂的制备与表征

以油酸、苯甲酸、氢氧化钙和氧化锌为主要原料,氧化植物油为溶剂,一锅化反应制备了油酸?苯甲酸钙/锌液体复合热稳定剂。采用刚果红试纸法和热老化法考察了其对聚氯乙烯（PVC）的静态热稳定性能及与辅助热稳定剂β?二酮、亚磷酸苯二异辛酯、季戊四醇间的协同作用。通过转矩流变仪、紫外光谱仪、场发射扫描电子显微镜测试了最优样品对PVC热稳定性能。结果表明,油酸?苯甲酸钙/锌液体复合热稳定剂对PVC的静态热稳定时间可达50 min,与亚磷酸苯二异辛酯具有最好的协同作用,最优样品对PVC的静态热稳定时间可达71 min,动态热稳定时间可达970 s,平衡扭矩37.3 N·m;紫外分析表明其具有较强地抑制共轭数3以上的共轭多烯生成的能力;其与PVC间的相容性较好,能均匀的分散在PVC颗粒表面,60 min前具有较好地抑制PVC降解的能力。     

Iodination of plasticized poly(vinyl chloride) in aqueous media via phase transfer catalysis

Nucleophilic substitution of chlorine on plasticized poly(vinyl chloride) (PVC) was carried out using potassium iodide (KI) in the presence of a phase transfer catalyst (PTC) in aqueous media. Iodination was confirmed using energy dispersive X‐ray analysis (EDAX). The extent of iodination was studied with respect to time, temperature, concentration of the reactants, as well as different PTCs. Among the different PTCs examined, tetrabutylammonium bromide (TBAB) and tetrabutylammonium hydrogen sulfate (TBAH) were found to be highly efficient for the reaction. About 25% increase in weight was observed for PVC sheets iodinated under optimal reaction conditions. The thermal stability of the modified PVC was found to be impaired upon iodination. The iodinated PVC released iodide ions when kept in distilled water, as evidenced by UV spectroscopy. Sustained release of iodide ion in distilled water was followed up for about 30 days. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 493–499, 2002; DOI 10.1002/app.10176     

Preparation of intercalated Mg‐Al layered double hydroxides and its application in PVC thermal stability

The Mg‐Al oxide precursor prepared by the calcination of Mg‐Al‐carbonated layered double hydroxide (LDH) at 500 K for 4 h is used as the host material, 2‐hydroxy‐4‐methoxybenzophenone‐5‐sulfonic acid (BP) is used as the guest material, BP‐intercalated LDH (LDH‐BP) is prepared by ion‐exchange method. The structure of LDH‐BP is characterized by X‐ray diffraction (XRD), Fourier transform infrared (FTIR), and thermogravimetry and differential thermal analysis (TG‐DTA). The thermal stability of PVC/BP, PVC/LDH, PVC/LDH‐BP composites, as well as pure PVC is investigated by conventional Congo Red test and dynamic thermal stability analysis in both the open and closed processing environments. According to XRD and FTIR, BP anions have been intercalated into interlayer galleries of LDH. TG‐DTA results show that the layer‐anionic interaction results in the improvement of the thermal stability of BP. Congo Red tests indicate that the addition of BP catalyzes the thermal degradation of PVC. A little amount of LDH (such as 1 phr) makes PVC more stable, but excessive addition accelerates the thermal degradation of PVC. The addition of LDH‐BP markedly improves the static thermal stability of PVC. The results of dynamic thermal stability tests in both the open and closed processing environments are consistent with that of Congo Red tests. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Photocatalytic degradation of organic dyes by a donor–acceptor type conjugated polymer: poly(thiophene‐1,3,4‐oxadiazole) and its photocatalytic mechanism

A donor–acceptor conjugated‐type polymer, poly(thiophene‐1,3,4‐oxadiazole) (PThOD), was synthesized by one‐step polycondensation in polyphosphoric acid. PThOD was confirmed and characterized using Fourier transform infrared spectra, thermogravimetric analysis, X‐ray diffraction and UV‐visible spectra. The UV‐visible spectra showed that PThOD could absorb not only in the whole ultraviolet range from 200 to 400 nm but also in the visible light range up to 500 nm. Considering the conjugated structure of PThOD, studies were carried out of its performance for the photocatalytic degradation of various dyes, such as methyl orange, methylene blue, rhodamine B and reactive brilliant blue (RBB), under medium‐pressure Hg light source irradiation. The results showed that PThOD was an effective photocatalyst, which could degrade the four types of dye solution. Besides, visible light was also used to investigate the degradation of RBB, and the results showed that RBB could be degraded as well, though the efficiency was not as high as using the Hg lamp. The superoxide anion radical (O₂^??), which is one of the reactive oxide species, was detected using the nitrotetrazolium blue chloride method and considered to play a key role in photodegradation of dyes. Moreover, various scavengers were also used to further prove the function of ^?. Furthermore, it was found that degradation rate could be changed by adding H⁺, which might be attributed to a change of adsorption capacity of PThOD. Finally, the reusability of PThOD as photocatalyst was investigated. The results indicated that the reusability efficiency of PThOD was excellent even after ten continuous rounds of use. © 2018 Society of Chemical Industry     

The modification of lanthanum‐exchanged montmorillonite with anionic surfactants to enhance the thermal stability of polyvinyl chloride

A series of thermally stable lanthanum organic montmorillonites (La‐OMMTs) were successfully prepared by modifying Na‐MMT with anionic surfactants and lanthanum chloride. Fourier transform infrared spectroscopy and X‐ray diffraction indicated that the anionic surfactants resided in the interlayer spaces and expanded the MMT basal spacing from 1.23 nm to 3.3 nm. Thermogravimetric and differential thermal analysis (TG/DTA) results showed that the intercalation of sodium dodecyl sulfonate into the lanthanum organic MMT resulted in its excellent thermal stability. The use of the La‐OMMT samples in polyvinyl chloride (PVC) resins was tested, and the TG/DTG results revealed that the three La‐OMMTs could significantly enhance the thermal stability of PVC. The modified La‐OMMT with the highest thermal stability is expected to be useful in polymer/layered silicate nanocomposites. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41535.     

Insights into the use of zinc–mannitol alkoxide as a novel thermal stabilizer for rigid poly(vinyl chloride)

Zinc–mannitol alkoxide (Zn–Man) was synthesized through alcohol exchange reaction, and investigated by means of Fourier transform infrared spectroscopy and elemental analysis. The thermal stability of Zn–Man for rigid poly(vinyl chloride) (PVC) was evaluated by Congo red testing, conductivity measurements, thermal aging testing, thermogravimetric analysis (TGA), and ultraviolet–visible (UV–vis) spectroscopy test. The experimental results demonstrate that the addition of Zn–Man not only apparently prolonged the static thermal stability time to approximately 96.5 min but also evidently improved the initial color of PVC. More importantly, the color of the PVC sheets stabilized with Zn–Man did not change to black within 180 min; this showed that no zinc‐burning phenomenon occurred. In addition, the results of TGA reveal that Zn–Man raised the initial degradation temperature of PVC to about 273.4°C. UV–vis testing indicated that the presence of Zn–Man decreased the content and shortened the length of the conjugated double bonds of PVC. The possible thermal stability mechanism is discussed. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42038.     

Study of poly(vinyl chloride)/acrylonitrile–styrene–acrylate blends for compatibility,toughness, thermal stability and UV irradiation resistance

A novel rigid poly(vinyl chloride) (PVC)/acrylonitrile–styrene–acrylate (ASA) copolymer blend with good ultraviolet (UV) irradiation resistance and toughness was reported. ASA with good weatherability and toughness was mixed with PVC by conical twin‐screw extruder to improve the UV irradiation resistance and toughness of PVC. The blends were characterized using Fourier‐transform infrared spectra, dynamic mechanical analysis, and scanning electron microscope. Notch Charpy impact test was used to characterize the UV radiation induced changes in toughness. The results showed that ASA was able to toughen PVC with simultaneously improving heat resistance, thermal stabilization, and protecting PVC from irradiation photochemical degradation. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 2143–2151, 2013     

A simple method to generate spontaneous chemisorption of metallic particles mediated by carboxylate groups from silylated oligomeric poly(amide‐imide)s

The present work describes oligomeric poly(amide‐imide)s (PAIs) containing several l ‐amino acidic residues and two silicon atoms in their repeat unit, whose carboxylate terminal group was chemisorbed onto metallic particles (Cu, Ag or Au) previously deposited in controlled conditions via physical vapor deposition. Thus, for each prepared polymer–metallic hybrid, the surface morphology, particle size distribution, and percentage of organic material, silicon and metal were studied using scanning electron microscopy and energy‐dispersive X‐ray spectroscopy. The results show that the hybrids are formed probably via electrostatic interaction between the carboxylate anions of the PAIs and nanoparticle cations. This bridging ligand was visualized using Raman spectroscopy and corroborated with X‐ray diffraction. Optical studies and resistivity measurements (conductivity) of each hybrid were developed using UV‐visible and the four‐point probe method, respectively. X‐ray photoelectron spectroscopy was used to study the oxidation states of the metallic particles at surface level. Thus, a simple and spontaneous protocol is proposed for the preparation of metallic particles stabilized in situ by an oligomer, a procedure that takes place from seconds to a few minutes. Finally, particle diameters were measured using atomic force microscopy in order to study possible agglomeration of the metallic particles with time. © 2017 Society of Chemical Industry     

Thermal and optical properties of gelatin/poly(vinyl alcohol) blends

Differential scanning calorimetry, thermogravimetric analysis, X‐ray diffraction, and ultraviolet–visible spectroscopy of gelatin and poly(vinyl alcohol) (PVA) homopolymers and their blended samples were studied. The data revealed that the gelatin and PVA polymers were compatible over the investigated range of compositions; this contributed to the formation of hydrogen‐bonding interaction between their polar groups. The associated enthalpy‐of‐melting transition and thermal stability of the blended samples increased with increasing PVA content. This indicated that the crystalline structure of PVA was not destroyed completely in the blends, which was consistent with the X‐ray diffraction pattern of the 50/50 (wt %/wt %) blended gelatin/PVA sample. The absorption edge and optical band gap for allowed direct transition were determined from ultraviolet–visible spectra. The induced changes in the band structure are elucidated. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Preparation and structural characterization of nanocrystalline poly(vinyl chloride)

This article describes the development of novel nanocrystalline poly(vinyl chloride) (PVC) for potential applications in PVC processes and reports improvements in the mechanical properties and thermal resistance. Before the preparation of nanocrystalline PVC via jet milling, PVC was spray‐treated and heat‐treated to improve its crystallinity. The pulverization and degradation, morphology, crystalline structure, and melting‐point changes of postmodified PVC during jet milling and the relationship between the distributions of the particle size and processing temperature were investigated. X‐ray analysis and density testing indicated increased density and improved crystallinity. The crystalline region of nanocrystalline PVC was less than 80 nm, with a particle size distribution of 5–20 μm and a melting point of less than 128°C. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 563–569, 2004     

The effect of layered double hydroxides dispersion on thermal and mechanical properties of poly(vinyl chloride)/poly(methyl methacrylate) blends

Poly(vinyl chloride) (PVC)/layered double hydroxide (LDH) composites and PVC/poly(methyl methacrylate) (PMMA)/LDH composites were prepared via solution intercalation into PVC using both unmodified and organo‐modified LDHs and variable‐molecular‐weight PMMA as additional components. The LDH dispersion was investigated using X‐ray diffraction analysis and electron microscopy in scanning and transmission modes. Spotlight fourier transform infrared (FTIR) chemical imaging analysis was also used to obtain a deeper insight into the dispersion of polymer phases and LDH segregation. Thermal properties were determined using thermogravimetric analysis and differential scanning calorimetry; moreover, a preliminary investigation of mechanical properties in tensile mode and evaluation of the Vicat softening temperature were carried out. The morphological analysis of PVC/LDH and PVC/PMMA/LDH composites evidenced in both cases the presence of disordered micro‐aggregates with loss of the LDH crystallographic symmetry depending on the amount and molecular weight of PMMA. In particular, in the case of PVC/PMMA/LDH composites, the FTIR imaging analysis showed that PMMA mostly segregated in the LDH phase. However, even if the degree of LDH dispersion was not elevated (micro‐aggregates with disordered structures and size ranging from 0.5 up to 11 µm were evidenced), thermal stability and mechanical properties of the composites were improved with a synergic effect of PMMA and LDH. © 2013 Society of Chemical Industry     

Thermal degradation behavior of poly(vinyl chloride) in presence of poly(N‐acryloyl‐N′‐cyanoacetohydrazide)

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     

Yttrium fumaropimarat as a novel heat stabilizer for poly(vinyl chloride)

Yttrium fumaropimarat (YFPA) was synthesized with fumaropimaric acid and yttrium acetate as raw materials. The structure of the product was analyzed and characterized by Fourier transform infrared spectrometer, scanning electron microscope, energy dispersive X‐ray microanalysis, and X‐ray diffraction. The results showed that the product was amorphous state, three‐dimensional reticulation compound by the ionic bond of COO^? and Y³⁺. The effect of YFPA on poly(vinyl chloride) (PVC) thermal stability was researched by means of Congo red method and heat oven aging method. The experimental results showed that YFPA was a good long‐term PVC thermal stabilizer and could greatly improve PVC thermal stability and initial stage stainability mixing calcium stearate, zinc stearate, and pentaerythrite. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 45015.     

哌嗪基单丁酰胺酸钙/锌的合成及对PVC热稳定性研究

以丁二酸酐、哌嗪、氯化钙、氯化锌为原料,通过两步反应制备了哌嗪基单丁酰胺酸钙/锌（PSACa/Zn）热稳定剂。采用元素分析、电感耦合等离子体原子发射光谱仪（ICP?OES）和傅里叶变换红外光谱仪（FTIR）对产品结构进行表征,通过刚果红试纸法、转矩流变仪法、热失重法考察了PSACa/Zn对PVC的热稳定性能,并筛选了PSACa和PSAZn的最佳配比。结果表明,PSACa和PSAZn对PVC的静态热稳定时间分别可达74.5、41.5 min,优于硬脂酸钙（CaSt₂）、硬脂酸锌（ZnSt₂）热稳定剂;PSACa和PSAZn复配使用时,以m_PSACa∶m_PSAZn=1∶1时性能最佳,对PVC静态热稳定时间可达92 min,动态热稳定时间可达905 s;发现PSACa/Zn对PVC的长期热稳定性良好。     

Interface engineering for the improvement of mechanical and thermal properties of covalent functionalized graphene/epoxy composites

Functionalized reduced graphene oxide (GO)/epoxy composites are fabricated through solution mixing. GO is functionalized using 3‐amino‐1,2,4‐triazole (TZ) in presence of potassium hydroxide (KOH). KOH is expected to serve dual role as catalyst for nucleophilic addition reaction between GO and TZ, and also as reducing agent. The grafting of TZ moiety on GO is confirmed by Fourier transform infrared spectroscopy, X‐ray diffraction, and thermogravimetric analysis. The prepared composites show remarkable improvement in mechanical and thermal stability. The fracture toughness of the composites (critical stress intensity factor, K_IC) achieved from single edge notched bending testing is improved by ～111% against pure epoxy at 0.1 wt % loading of TZ functionalized GO. Further, the tensile strength and Young's modulus are improved by ～30.5% and 35%, respectively. Thermal stability of the composites as investigated by thermogravimetric analysis showed 29 °C rise in onset degradation temperature for 0.1 wt % TZ functionalized GO incorporated composite. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46124.