Thermal stability of poly(vinyl chloride) with epoxidised soybean oil as primary plasticizer

Epoxidised soybean oil (ESBO) has been tested as a primary plasticizer in suspension PVC. The stabilization of the material with different traditional stabilizers has been evaluated and compared to a compound with PVC-ESBO only. Surprisingly, the addition of stabilizers seems to decrease the stability of PVC-ESBO. Traditional stabilizers, for instance Ca/Zn-stearate have been evaluated as well as metal carboxylates regarding yellowness index and UV-Vis absorption. Among the metal carboxylates, a decrease in initial discolouration, i.e. yellowness was observed with addition of Zn-stearate whereas the addition of Al-stearate improved the colour after ageing compared to PVC-ESBO without stabilizer.The stabilizing mechanism of ESBO itself, without the addition of stabilizers, has also been investigated. Analyses with ion chromatography of ESBO extracted from PVC samples without stabilizer revealed that the chlorine content of ESBO had increased when ageing the sample. MALDI analysis revealed that hydrochloric acid likely had attached to the ESBO. Reactions between ESBO and PVC were found through NMR analysis.     

Interactions between poly(vinyl chloride) stabilised with epoxidised sunflower oil and food simulants

Commercial sunflower oil was epoxidised and used as organic co-stabiliser for rigid and plasticised poly(vinyl chloride) (PVC) containing Zn and Ca stearates as primary stabilisers and stearic acid as lubricant. For applications in the packaging of foodstuffs, migration testing must be performed. The detection and the quantification of contaminants migrating from the polymer into the food simulants are essential for the safety assessment of food contact plastic packaging materials. For that purpose, two food simulants were used: olive oil and 15% (v/v) aqueous ethanol. These represent fatty and moist food and beverages, respectively. The test conditions were 12 days at 40 °C. Circular samples of rigid PVC and PVC plasticised with dioctyl phthalate were immersed in a known volume of food simulant. A circular sample and 10 ml of food simulant were taken off every day to be analysed. Each sample was wiped and weighed. The rate of variation of the mass was determined as a function of time. The evolution of the peroxide index of olive oil with time was analysed. The specific migrations of the present additives were investigated by using two analytical methods (atomic absorption spectrometry and Fourier transform infrared spectroscopy). The influence of various parameters such as the nature of food simulant, the presence or the absence of the plasticiser, the agitation and time of contact was considered.     

Latex interpenetrating polymer networks of epoxidised natural rubber/poly(methyl methacrylate): an insight into the mechanism of epoxidation

Composite latex particles consisting of epoxidised natural rubber (ENR) and poly(methyl methacrylate) (PMMA) were synthesised to obtain interpenetrating polymer networks. Among the ENR latices having 9 to 36 mol% epoxide, prepared by in situ reaction using performic acid, the ENR latex with 25 mol% epoxide was selected for prevulcanisation by sulphur or γ-radiation system. The swelling ratios of sheets cast from the sulphur-prevulcanised ENR (SPENR) latices decreased with increasing prevulcanisation time while those cast from the γ-radiation-prevulcanised ENR latices were also inversely proportional to the irradiation dose. By applying the phase transfer/bulk polymerisation/transmission electron microscopy (TEM) technique, a homogeneous network structure in each of the SPENR particles and also a relative dense network near the surface in γ-radiation (RV) ENR particle were noticed. When 10 to 30 wt% of MMA swollen in ENR particles was polymerised, the mesh structure was observed in each particle. The dense network near the RVENR particle surface might be used as additional evidence that the degree of epoxidation and, hence, the presence of swollen n-butyl acrylate in the outer zone were higher than in the internal region.     

SO42-/ZrO2的制备工艺对催化橡胶籽油裂解油酯化的影响

以SO₄^2-/ZrO₂为催化剂对橡胶籽油裂解油进行甲酯化。研究了锆源、焙烧温度及焙烧时间对催化剂活性的影响,分别采用氨气吸附程序升温脱附(NH₃-TPD)和吡啶红外(Py-IR)对固体酸SO₄^2-/ZrO₂的酸性和酸型进行分析。实验结果表明,以ZrOCl₂为锆源,550℃焙烧4 h所得固体酸SO₄^2-/ZrO₂的催化活性最好,性能较稳定。对酯化产物的组成及性能进行了考察,结果表明,酯化产物的各项性能均优于传统工艺制备的生物燃油,且与0^#柴油相近。     

Thermal Behaviour of PVC/Poly(MMA-co-DVB) Polymer Systems and Membranes Based on PVC/Poly(MMA-co-DVB) Systems

The thermal stabilities of PVC/poly(MMA-co-DVB) polymer systems and membranes prepared by the paste method were investigated. The thermoanalytical curves were used to determine the main thermal stage of the decompositions. It was found that the thermal properties of the polymer systems were affected by the divinylbenzene content. A membrane based on the PVC/poly(MMA-co-DVB) system with 5 mass% DVB displays thermal stability up to 210°C. This revised version was published online in July 2006 with corrections to the Cover Date.     

Effect of stearate preheating on the thermal stability of plasticized PVC compounds

Effect of preheating of stearates on the processing and post-processing thermal stability of poly(vinyl chloride) compounds, plasticized with di(2-ethylhexyl) phthalate (DEHP) and epoxidized soybean oil (ESO), using several ratios of calcium/zinc stearates and DEHP/ESO is reported. The compounds were prepared as follows: (1) dry-blending the compound components, (2) pelletizing the dry-blend and (3) extruding the pellets to obtain a ribbon geometry. Processing stability was determined by: (a) mechanical characterization and (b) visual color comparison of extruded samples. Post-processing thermal stability was followed by: (a) measurement of HCl release from heated pellets and (b) color changes in heated ribbon samples. From a practical point of view, the preheating has a negligible effect on the initial color of formulations; except for the case of formulations without both ESO and CaSt₂. However, the effect of the preheating on the post-processing thermal stability is strongly determined by the composition formulation.     

The effect of alkanolamide loading on properties of carbon black-filled natural rubber (SMR-L), epoxidised natural rubber (ENR), and styrene-butadiene rubber (SBR) compounds

The effect of Alkanolamide (ALK) loading on properties on three different types of carbon black (CB)-filled rubbers (SMR-L, ENR-25, and SBR) was investigated. The ALK loadings were 1.0, 3.0, 5.0 and 7.0 phr. It was found that ALK gave cure enhancement, better filler dispersion and greater rubber–filler interaction. ALK also enhanced modulus, hardness, resilience and tensile strength, especially up to 5.0 phr of loading in SMR-L and SBR compounds, and at 1.0 phr in ENR-25 compound. Scanning electron microscopy (SEM) proved that each optimum ALK loading exhibited the greatest matrix tearing line and surface roughness due to better rubber - filler interaction.     

Effect of montmorillonite treatment on the thermal stability of poly(vinyl chloride) nanocomposites

The aim of this research was to study the effect of different intercalants on the thermal degradation/dehydrochlorination of poly(vinyl chloride) (PVC). PVC nanocomposites were prepared containing 2 phr of montmorillonite clay. The montmorillonite was treated with different organic intercalants and analysed by thermogravimetric analysis and X-ray diffraction. All intercalants were found to intercalate the clay. The nanocomposites were prepared on a two-roll mill and pressed into 0.7 mm thick plates. The degradation was analysed by yellowness index, Congo red test and UV–visible spectroscopy. All cationic intercalants were found to accelerate the dehydrochlorination of PVC whereas the non-ionic did not affect thermal degradation. On the other hand, some non-ionic intercalants showed poor dispersion.     

Influence of Fe‐MMT on crosslinking and thermal degradation in silicone rubber/clay nanocomposites

In this article, silicone rubber (SR)/clay nanocomposites were synthesized by a melt‐intercalation process using synthetic Fe‐montmorillonite (Fe‐MMT) and natural Na‐MMT which were modified by cetyltrimethyl ammonium bromide (CTAB). This study has been designed to determine if the presence of structural iron in the matrix can result in radical trapping and then enhance thermal stability, affect the crosslinking degree and elongation. The SR/clay nanocomposites were characterized by X‐ray diffraction (XRD) patterns and transmission electron microscopy (TEM). Exfoliated and intercalated nanocomposites were obtained. Thermo gravimetric analysis (TGA) and mechanical performance were applied to test the properties of the SR/clay nanocomposites. The presence of iron significantly increased the onset temperature of thermal degradation in SR/Fe‐MMT nanocomposites. The thermal stability, gel fraction and mechanical property of SR/Fe‐MMT were different from the SR/Na‐MMT nanocomposites. So the iron not only in thermal degradation but in the vulcanization process acted as an antioxidant and radicals trap. Copyright © 2006 John Wiley & Sons, Ltd.     

Insight the mechanism of MgAl/layered double hydroxide supported on rubber seed shell biochar for Remazol Brilliant Violet 5R removal

The ever-increasing concentration of Remazol Brilliant Violet 5R discharged mainly from textile industry had cause serious environmental issues towards human and the surrounding ecosystem. Therefore, solving the issue related to dye contamination is seriously important. In this research study, MgAl/layered double hydroxide supported on rubber seed shell biochar (RSSB) had been prepared for Remazol Brilliant Violet 5R (RBV5R) dye adsorption. BET surface area and pore volume of RSSB were found to be 132.40 m²/g and 0.0732 cm³/g, respectively with presence of LDH metals on the RSSB surfaces. The batch adsorption studies showed that RBV5R uptake capacity was significantly enhanced (125.88 mg/g) compared to pristine RSSB (58.69 mg/g) at initial RBV5R concentration, contact time, adsorption temperature and pH of 300 mg/l, 1440 min, 60 °C and pH 2, respectively. The equilibrium and kinetic adsorption data were best fitted into the Freundlich and pseudo-first order model, respectively. The thermodynamic study confirmed the RBV5R adsorption was endothermic in nature and governed by physisorption process. All these findings signified that the MgAl/LDH-RSSB is a promising adsorbent for treating wastewater containing RBV5R dye.     

The morphology and thermal properties of liquid natural rubber (LNR)-compatibilized 60/40 NR/LLDPE blends

The effects of LNR as a compatibilizer in binary blends of 60/40 NR/LLDPE have been investigated by means of differential scanning calorimetry, dynamic mechanical analysis and scanning electron microscopy. Special emphasis was given to the role of LNR in inducing interactions between NR and LLDPE. It has been observed that increasing LNR content decreases T_m and ΔH_f which are indicators of the crystalline part of the blends. The decrease reflects a reduction in the degree of crystallinity which is due to the interference in the form of NR dissolution into the LLDPE phase. The phenomenon leads to a shift in T_g of the amorphous part of LLDPE to higher temperatures as observed by DMA thermograms. The dissolution effect creates better interactions between the phases leading to improvements in the compatibility of the blends. Further confirmation was obtained through SEM examination.     

Investigation of aging behavior and mechanism of nitrile-butadiene rubber (NBR) in the accelerated thermal aging environment

Nitrile-butadiene rubber (NBR) was exposed to an accelerated thermal aging environment produced by an air-circulating oven for different time periods. NBR aging was evaluated by morphology, crosslink density, mechanical properties, chemical changes and thermal stability. The results showed that the surface damage of NBR turned severe and inhomogeneous, and the aging degree was most serious on the edge region of voids. Crosslinking reactions mainly occurred in the aging process. The tensile strength increased with increase in crosslink density up to a maximum value and thereafter decreased with further increase in crosslink density. X-ray Photoelectron Spectroscopy (XPS) and Pyrolysis Gas Chromatography-Mass Spectrometry (Py-GC/MS) analysis demonstrated that hydroxyl groups were formed and the additives migrated from inner to surface of NBR samples. In addition, the thermogravimetric analysis (TGA) indicated that the thermal stability of NBR did not significantly change in the accelerated thermal aging environment.     

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.     

Investigations on thermal stability of adduct aluminium nitrate(V)-urea (1/6)

The adduct of Al(NO₃)₃·6CO(NH₂)₂ has been prepared and characterized by means of chemical analysis, IR spectroscopy, X-ray patterns and microscopy. A thermoanalytical study of Al(NO₃)₃·6CO(NH₂)₂ as well as urea, for comparison purposes, under conventional dynamic and quasi-isothermal—quasi-isobaric conditions in air has been carried out. It has been found that the adduct is thermally stable up to about 200°C, i.e. up to higher temperature than the decomposition temperature of the constituent compounds. The thermal decomposition mechanism of the adduct is complex, thus infrared spectroscopy and X-ray diffraction techniques have been used to determine the intermediate products. Aluminium oxide(III) is the final decomposition product.     

Kinetic and thermodynamic parameters of the thermal decomposition of zinc(ii) dialkyldithiocarbamate complexes

The thermodynamic and kinetic parameters of the thermal decomposition of Zn(S₂CNR₂)₂ complexes (R=CH₃, C₂H₅ and n-C₃H₇) were determined with the dynamic thermogravimetric method. Superimposed TG/DTG/DSC curves show that thermal decomposition reactions for chelates with R=C₂H₅ and n-C₃H₇ occur in the liquid phase, at temperatures far away from their melting points, whereas for the complex with R=CH₃ the thermal decomposition begins at a temperature closer to its melting point, suggesting a rather complex decomposition mechanism. This revised version was published online in August 2006 with corrections to the Cover Date.     

Preparation of poly(phenylsilsesquioxane) (PPSQ) particles with ladder structure and the thermal stability of PP/PPSQ composites

The poly(phenylsilsesquioxane) (PPSQ) particles were prepared with both basic and acidic catalyzed processes and the PP/PPSQ composites were prepared by melt blending method. Studies on PPSQ by Infrared (IR), X‐ray diffraction (XRD), ²⁹Si cross polarized (CP) nuclear magnetic resonance (NMR) spectroscopy showed that the structure of PPSQ was ladder structure. The results of scanning electron microscopy (SEM) confirmed that the prepared PPSQ particles were about 2 µm with narrow size distributions. The morphology and thermal stability of PP/PPSQ composites were characterized by SEM, XRD, and thermogravimetric analysis (TGA). The SEM result showed that the particles were well dispersed in the PP matrix and the XRD revealed that the addition of PPSQ influences the crystallinity and crystal orientation of PP. The thermogravimetric analysis results of the PP/PPSQ composites indicated that the incorporation of PPSQ can improve the thermal stability of PP. The Flynn–Wall–Ozawa method was employed to analyze the TGA data and the kinetic results showed that the apparent activation energy for PP/PPSQ composites was much higher than that of neat PP, suggesting that the PPSQ influences the mechanisms of pyrolysis of PP. Copyright © 2010 John Wiley & Sons, Ltd.     

Effects of thermal stability on the crystallization behavior of poly(vinylidene chloride)

Thermal analysis based on TGA (thermal gravimetric analysis) and DSC (differential scanning calorimeter) shows no significant degradation for PVDC which has been annealed at 210°C for less than 2 min. And the following recrystallization behavior at lower temperature (120°C) is also independent of the thermal treatment and is not affected by the difference of molecular weight. The degradation which includes dehydrochlorination at lower temperature and intramolecular cyclization or intermolecular crosslinking of the polyenes at higher temperature starts when the melting time at 210°C is more than 2 min, which also causes weight loss and heat exchange in the TGA and DSC thermograms. The recrystallization behavior of the degraded PVDC (staying at 210°C for more than 2 min) shows a strong dependence on the molecular weight. The crystallinity is decreased with the melting time at 210°C due to the increase of the degree of crosslinking. However, the POM (polarized optical microscopy) pictures and IR spectra show a favorable nucleation effect is present due to the formation of trichlorobenzene from the cyclization of the polyenes as nuclei. The crystallinity of the PVDC recrystallized at 120°C after staying at 210°C for more than 2 min is actually dependent on the molecular weight, melting time at 210°C, and cyclized or crosslinking types of degradation. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 3269–3276, 1999     

Characterization and thermal stability of poly(vinyl chloride) plasticized with epoxidized soybean oil for food packaging

The use of phthalates in plasticized poly(vinyl chloride) (PVC) formulations has been questioned by their potential toxicity and high migration to foodstuff. Phthalates can be replaced by other harmless and environmentally friendly plasticizers, such as epoxidized soybean oil (ESBO), which has been also proved an efficient stabilizer for PVC helping to prevent degradation during processing. Formulations based on PVC with different amounts of ESBO (from 30 to 50 wt%) were fully characterized showing good compatibility and a clear increase in thermal stability. An evaluation of the use of ESBO for PVC stabilization in commercial lids was carried out by using thermogravimetric analysis (TGA). ESBO was detected in all materials and their thermal stability was highly dependent on the plasticizer concentration. Most of them showed a significant increase in thermal degradation temperatures, permitting their use in food processing at high temperatures without risk of degradation.     

Effect of the modification of silica on thermal properties and flammability of cross-linked butadiene-acrylonitrile rubbers

The paper presents the results of testing the thermal stability and flammability of butadiene-acrylonitrile rubber vulcanizates with different contents of combined acrylonitrile: Perbunan NT 1845 and Perbunan NT 3945 from Bayer, containing unmodified and bromine- or iodine-modified silica. The test results were obtained with the use of a derivatograph, measurements of flammability by the method of oxygen index, in air and also with the use of a cone calorimeter. The effect of the modification on the zeta potential was also examined. A considerable reduction in the flammability of nitrile rubber vulcanizates filled with silica can be obtained by the modification of filler with bromine or iodine. All the vulcanizates containing modified silica are self-extinguishing. An appropriate filling of NBR 39 vulcanizates with bromine-modified silica makes it possible to obtain non-flammable polymeric materials. They neither ignite nor glow under the action of a flame source for 30 s. The findings can be a rational basis for the synthesis of modified silica that can act as active filler and effective flame-retardant agent at the same time.     

Studies of the effects of copper, copper(II) oxide and copper(II) chloride on the thermal degradation of poly(vinyl chloride)

Investigations of the pyrolysis of poly(vinyl chloride) (PVC) in the presence of copper metal (Cu), copper(II) oxide (CuO) and copper(II) chloride (CuCl₂) are of potential importance because of the likelihood of the formation of these copper compounds during the thermal degradation of PVC-coated copper wires, a step in the recovery of copper from waste. The presence of Cu, CuO and CuCl₂ (i) retards the thermal degradation of PVC in air and in nitrogen and (ii) decreases the percentages of volatile products produced at both stages of the decomposition. These effects are greatest for PVC-CuO. The presence of copper, CuO or CuCl₂ in PVC has a major effect on the nature of the gaseous emissions of the thermal decomposition in air and in nitrogen. The concentrations of total chlorine, aliphatic hydrocarbons, aromatic hydrocarbons, chlorinated hydrocarbons and soot particulates are all affected relative to an equivalent amount of PVC. These changes are greatest for the PVC-CuO system for which total chlorine emissions in air and nitrogen are reduced by 40% in air and 20% in nitrogen, benzene emissions are reduced by greater than 90% in air and nitrogen, other aromatic and chloroaromatic emissions are reduced, and soot particulate emissions are reduced by more than 50% as the concentrations of aliphatic compounds are increased. These changes are consistent with the presence of copper or its compounds permitting more efficient combustion of the carbon content of the PVC and particularly in the case of PVC-CuO with the removal of chlorine during pyrolysis in the inorganic phase.