Supercritical CO2 extraction of phthalate plasticizers from PVC

Three common phthalates, namely, dioctyl phthalate, diisodecyl phthalate, and trioctyl trimellitate, were used as plasticizers for poly(vinyl chloride) (PVC) processing, and the extraction of these plasticizers were investigated using supercritical CO₂ fluids. Factors affecting the extractions of these phthalates were focused. The molecular weight of phthalates was found to dominate the level of extraction of low temperatures, whereas the content of carbonyl groups in the phthalate was a determining factor for the level of extraction of high temperatures. Negligible extraction was observed below the critical pressure of CO₂. For 32°C, the level of the extraction is insignificant below density of ca 0.7 g/cm³, above which the level of the extraction increases roughly linearly with increasing density. For temperatures above 32°C, the density of CO₂ for apparent extractions decreased with increasing temperatures. The threshold density of CO₂ for extractions was found to be independent of the amount of a given phthalate in PVC. Two extraction rates during the extraction could be determined, with a higher rate in the first hour followed by a lower rate later in the extraction for all three phthalates. The effects of the extractions of phthalates on the flexibility of PVC were also investigated as well as the effects of the extrusion conditions, which could lead to various degrees of plasticization of PVC, on the level of extractions. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 4032–4037, 2003     

Effect of liquid plasticizers on crystallization of PCL in soft PVC/PCL/plasticizer blends

In this work, poly(ε-caprolactone) (PCL) and liquid plasticizer were combined used to plasticize poly(vinyl chloride) (PVC), and the possibility of using PVC/PCL/plasticizer blends to fabricate soft PVC with enhanced migration resistance was investigated. Through partial replacement of liquid plasticizers in soft PVC by equal quantity of PCL, flexibility was maintained while extraction loss of plasticizer by organic solvent was reduced significantly. Furthermore, crystallization of PCL in PVC/PCL/plasticizer blends with low PCL content was observed, and crystallization rate of PCL was found to be influenced by plasticizer contents and structures. For instance, crystallization rate of PCL in PVC/PCL/diisononyl phthalate (DINP) (100/40/100) was 3.7 times faster than in PVC/PCL/DINP (100/40/80), while crystallization rate of PCL in PVC/PCL/dioctyl adipate(DOA)(100/40/100) was 8.3 times faster than in PVC/PCL/diisononyl cyclohexane-1,2-dicarboxylate (DINCH) (100/40/100). Low-field ¹H NMR test manifested that different crystallization rate of PCL in PVC/PCL/plasticizer blends with different plasticizer structures was triggered by difference in plasticizers' compatibility with PVC, that is, the number of interaction point between PVC and plasticizers. It is concluded that PCL crystallization favored by liquid plasticizers in PVC/PCL/plasticizer blends was induced by interaction competition between PVC/plasticizer and PVC/PCL. As plasticizer content increases or its compatibility with PVC decreases, interaction competition becomes more intense and consequently faster crystallization of PCL occurs. Thus, to obtain soft PVC products with improve migration resistance while avoiding PCL crystallization, the total content of plasticizer (including both liquid plasticizer and PCL) should be lower than 66 phr (40 wt %). © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48803.     

Concentration dependency of interaction parameter between PVC and plasticizers using inverse gas chromatography

The inverse gas chromatography method was extended to study the concentration dependent Flory–Huggins interaction parameter between poly(vinyl chloride) (PVC) and plasticizers using literature data. For both PVC/polyadipate and PVC/epoxidized soybean oil (ESO) systems, the miscibility was better at the high PVC end. The specific interaction between PVC and plasticizers was estimated from the difference between the experimental results and the enthalpies of mixing predicted by the solubility parameter model. The interaction was negative and skewed toward the high PVC end, and rendered the overall interaction parameter negative at high PVC compositions. Chemical potential was used to determine the phase composition of PVC/plasticizer mixtures. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 146–156, 2004     

Use of compatible blends to fabricate carbon black composite vapor detectors

The aim of this work was the development of materials to be used in the field of gas sensing for the detection of organic vapors. Conductive sensors were prepared with carbon black filled blends of poly(vinyl chloride) and diol‐terminated poly(?‐caprolactone), an oligomeric plasticizer. For comparison, blends with di(2‐ethylhexyl)phthalate, a traditional low‐molecular‐weight plasticizer, were also prepared. All sensors were tested upon exposure to different organic vapors. In general, the plasticizer content affected the response rates of the sensors, and a linear variation of the relative resistance with the analyte concentration was observed. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 1816–1821, 2004     

Mechanical properties of recycled PVC blends with styrenic polymers

The aim of this study is to improve the performance of blends made from recycled polyvinyl chloride (PVC), coming from credit card waste, so that these blends can be used for those applications that must fulfil some requirements with regard to mechanical properties and stability with temperature alterations. With this aim in mind, two polymers of styrenic origin have been combined: styrene acrylonitrile (SAN) and acrylonitrile butadiene styrene (ABS). These polymers are characterized by a satisfactory balance of mechanical properties and thermal stability. PVC blends with both virgin and recycled styrenic polymers have been studied throughout the entire range of compositions. The prior degradation of the recycled materials has been studied by means of Fourier transformed infrared spectroscopy (FTIR).The behavior of the observed T_g values has been analyzed using differential scanning calorimetry (DSC), and the existence of partial miscibility between the different components has been studied. The mechanical properties have been determined using tensile and Charpy impact tests. The thermal stability of the PVC blends with temperature changes has been determined using the Vicat softening temperature (VST). Finally, the fracture surface of the various blends has been analyzed using scanning electron microscopy (SEM). © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 2464–2471, 2006     

Processability,rheology, and thermal,mechanical, and morphological properties of postconsumer poly(vinyl chloride) bottles and cables

The processability, rheology, and thermal, mechanical, and morphological properties of three different commercial poly(vinyl chloride) (PVC) compounds blended with postconsumer PVC bottles and PVC cables were examined with respect to the recycled PVC content. The addition of PVC bottle recyclates [recycled bottles (RBs)] into virgin PVC bottle (VB) and virgin PVC pipe (VP) compounds caused a progressive reduction in the average torque. No thermal degradation or color change in the RB‐blended PVC compounds used was detected through carbonyl and polyene indices from IR analysis. The rheological properties for VP compounds were more sensitive to RB addition than those of VB compounds. The extrudate swell ratio did not change with the RB content. The decomposition temperature for the VB and VP compounds increased at 60–80% RB, whereas the glass‐transition temperature was unaffected by the RB loading. The 20 and 80 wt % RB loadings were recommended for the VB and VP compounds, respectively, for the optimum impact strength, the blends showing ductile fracture with a continuous phase. At the optimum impact and tensile properties, introducing RB recyclates into the VB compounds gave better results than the VP compounds. The hardness and density of the VB and VP compounds did not change with the RB content. The RB property change was comparatively faster than that of recycled PVC pipes. Adding the PVC cable recyclate [recycled cable (RC)] to virgin PVC cable (VC) had no obvious effect on the torque value of the RC/VC blends. The decomposition temperatures of the RC/VC blends stabilized at 20–60% RC and tended to decrease at 80% RC. The ultimate tensile stress was improved by the addition of the RC compounds, whereas the hardness and density of the VC compounds were unaffected by the RC content. It was concluded that the optimum concentrations of PVC recyclates to be added to virgin PVC compounds were different from one property to another and also depended on the type of virgin PVC grade used. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2738–2748, 2003     

New aminated PVC compounds: Synthesis and characterization

Different compounds for the synthesis of poly(vinyl chloride) (PVC) with tertiary amino groups were tested, and the course of the modification reactions was followed under different conditions by nuclear magnetic resonance spectroscopy and elemental analysis. It is shown that PVC can be modified without side reactions with 2‐mercaptopyridine, 2‐mercaptopyrimidine, 4‐mercapto‐N,N‐dimethylaniline, and 4‐mercaptopyridine. The reactivity of the para‐substituted mercapto compounds is found to be considerably higher than that of the corresponding ortho products, and higher final degrees of modification are achieved. The availability of the amino group towards electrophilic attack in order to form quaternary ammonium salts was tested by reaction with methyl iodide. While this reaction takes place in good yields in the case of PVC modified with 4‐mercaptopyridine and 4‐mercapto‐N,N‐dimethylaniline, aminated PVC with the nitrogen atoms in ortho position do not react due to steric hindrance by the polymer chain. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 1178–1185, 1999     

Environmentally friendly plasticizers for poly(vinyl chloride)—Improved mechanical properties and compatibility by using branched poly(butylene adipate) as a polymeric plasticizer

Linear and branched poly(butylene adipate)s (PBA) with molecular weights ranging from 2000 to 10,000 g/mol, and a branching agent content between 0 and 1.8%, were solution cast with poly(vinyl chloride) (PVC) to form 50‐ to 60‐μm thick flexible films. Dry films were analyzed by tensile testing, Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), and optical microscopy (OM) to study the effects of molecular weight and branching on the plasticizing efficiency of the polyester. PBA formed a semimiscible two‐phase system with PVC, where the amorphous part exhibited a single glass transition temperature. The degree of crystallinity for the polyester, surface composition, and mechanical properties of the films depended on the blend composition, molecular weight, and degree of branching of the polyester. Plasticizing efficiency was improved by higher degree of branching. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 2180–2188, 2006     

Fourier transform infrared spectroscopy in the study of the interaction between PVC and plasticizers: PVC/plasticizer compatibility

The interactions between Poly(vinyl chloride) (PVC) and Plasticizers, responsible for polymer plasticization, can be detected by means of Fourier transform infrared spectroscopy (FTIR). The interaction capacity between the two components depends on plasticizer chemical nature, PVC stereoregularity, and plasticizer content. In the case of ternary systems, consisting in PVC and two different plasticizers, their interaction with PVC depends essentially on their chemical nature. In this work, FTIR spectroscopy is applied to determine the effect of the cited factors on the compatibility between plasticizer and resin. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Effects of acrylic‐based processing aids on processibility,rheology, thermal and structural stability,and mechanical properties of PVC/wood–sawdust composites

Methyl methacrylate and ethylacrylate (MMA‐co‐EA) and methyl methacrylate and butylacrylate (MMA‐co‐BA) copolymeric processing aids were introduced into poly(vinyl chloride) (PVC)/33.3 wt % wood–sawdust composites containing 0.6 and 2.4 phr of calcium stearate lubricant. The properties of the composites were monitored in terms of processibility, rheology, thermal and structural stability, and mechanical properties. It was found that the mixing torque, wall shear stress, and extrudate swell ratio increased with increasing processing aid content because of increased PVC entanglement. MMA‐co‐BA (PA20) was found to be more effective than MMA‐co‐EA (K120 and K130), this being associated with the flexibility of the processing aids, and the dipole–dipole interactions between sawdust particles and polymeric processing aids. The sharkskin characteristic of the composite extrudate at high extrusion rate was moderated by the presence of processing aids. Adding the acrylic‐based processing aids and lubricant into PVC/sawdust composites improved the thermal and structural stability of the composites, which were evidenced by an increase in glass transition and decomposition temperatures and a decrease in polyene sequences, respectively. The changes in the mechanical properties of the composites involved a composite homogeneity, which was varied by degree of entanglement and the presence of wood sawdust, and un‐reacted processing aids left in the composites. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 782–790, 2004     

Preparation of poly(vinyl chloride) (PVC) ultrafiltration membranes from PVC/additive/solvent and application of UF membranes as substrate for fabrication of reverse osmosis membranes

Ultrafiltration (UF) membranes were prepared from poly(vinyl chloride) (PVC) as main polymer, poly(vinyl pyrrolidone) (PVP) as additive, and 1‐methyl‐2‐pyrrolidone (NMP) as solvent using Design Expert software for designing the experiments. The membranes were characterized by SEM, contact angle measurement, and atomic force microscopy. The performance of UF membranes was evaluated by pure water flux (PWF) and blue indigo dye particle rejection. In addition, the molecular weight cutoff of UF membranes was determined by poly(ethylene glycol) (PEG) rejection. The UF membranes were used as substrates for fabrication of polyamide thin film composite (TFC) reverse osmosis (RO) membranes. The results showed that the model had high reliability for prediction of PWF of UF membranes. Also, increment in PVC concentration caused reduction of PWF. Moreover, at constant PVC concentration and if the concentrations of PVC was lower than 10 wt %, the PWF reduced by increasing the concentration of PVP. However, at PVC concentration higher than 11 wt %, increment in PVP concentration showed increment and reduction of PWF. The PEG rejection results showed that the prepared membranes had UF membranes properties. Finally, the NaCl rejection tests of RO membranes by PVC as substrates indicated that the performance of RO membranes were lower than commercial membranes. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46267.     

Blends of plasticized poly(vinyl chloride) and waste flexible poly(vinyl chloride) with waste nitrile rubber powder

Blends of poly(vinyl chloride) (PVC) with varying contents of plasticizer and finely ground powder of waste nitrile rubber rollers were prepared over a wide range of rubber contents through high‐temperature blending. The effects of rubber and plasticizer (dioctyl phthalate) content on the tensile strength, percentage elongation, impact properties, hardness, abrasion resistance, flexural crack resistance, limiting oxygen index (LOI), electrical properties, and breakdown voltage were studied. The percentage elongation, flexural crack resistance, and impact strength of blends increased considerably over those of PVC. The waste rubber had a plasticizing effect. Blends of waste plasticized PVC and waste nitrile rubber showed promising properties. The electrical properties and LOI decreased with increasing rubber and plasticizer content. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 1552–1558, 2004     

Evaluating effects of biobased 2,5‐furandicarboxylate esters as plasticizers on the thermal and mechanical properties of poly (vinyl chloride)

We synthesized 2,5‐furandicarboxylate esters [i.e., dibutylfuran‐2,5‐dicarboxylate, diisoamylfuran‐2,5‐dicarboxylate, and di(2‐ethylhexyl)furan‐2,5‐dicarboxylate] and investigated their potential application as plasticizers of commercial poly(vinyl chloride) (PVC) products. Fourier transform infrared analysis, mechanical tests, scanning electron microscopy investigation, differential scanning calorimetry analysis, dynamic mechanical thermal analysis, thermogravimetric analysis (TGA), melt flow rate (MFR) measurement, and plasticizer migration measurements were used to the evaluate the comprehensive properties of the blended products. The results of the tensile tests demonstrate that the blends exhibited antiplasticization and flexible plastic characteristics at 10 and 50 phr in PVC, respectively. Moreover, flexural and impact test data indicate that the three types of blends exhibited a similar tendency: the hardness decreased continuously as the amount of plasticizer increased. Their morphology indicated that all of the plasticizers had good compatibility with PVC. The resulting glass‐transition temperature of the investigated plasticizers was lower than that of pure PVC, and reduction was largest for the plasticizer with the highest molecular weight. TGA revealed that the thermal degradation of blended polymers occurred in three stages and that all of the blends were stable up to 180°C. Finally, the MFRs of all of the specimens indicated that the addition of a higher concentration of lower molecular weight biobased esters resulted in improved fluidity, but these compounds migrated more easily from the blends. Hence, 2,5‐furandicarboxylic acid derived from biomass has potential as a plasticizer. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40938.     

Soft PVC foams: Study of the gelation,fusion, and foaming processes. II. Adipate,citrate and other types of plasticizers

Plasticized poly(vinyl chloride) (PVC) is one of the most useful polymeric materials on an industrial scale because of its processability, wide range of obtainable properties, and low cost. PVC plastisols are used in the production of flexible PVC foams. Phthalates are the most used plasticizers for PVC, and in a previous article (part I of this series), we discussed the influence of phthalate ester type plasticizers on the foaming process and on the quality of the foams obtained from the corresponding plastisols. Because the use of phthalate plasticizers has been questioned because of possible health implications, the objective of this work was to undertake a similar study with 11 commercial alternative plasticizers to phthalates. The evolution of the dynamic and extensional viscosity and the interactions and thermal transitions undergone by the plastisols during the heating process were studied. Foams were obtained by rotational molding and were characterized by the determination of their thermomechanical properties, density, and cell size distribution. Correlations were obtained between the molecular weight and structure of the plasticizer and the behavior of the corresponding plastisols. After the characterization of the final foamed product, we concluded that foams of relatively good quality could be prepared with alternative plasticizers for replacing phthalates. Several plasticizers {Mesamoll (alkylsulfonic phenyl ester), Eastman 168 [bis(2‐ethylhexyl)‐1,4‐benzenedicarboxylate], Hexamoll [di(isononyl) cyclohexane‐1,2‐dicarboxylate], Citroflex A4 acetyl tributyl citrate (ATBC), and Plastomoll (dihexyl adipate)} were found to be interesting alternatives in the production of soft PVC foams because they provided very good quality foams with properties similar to, or even better than, those obtained with phthalate plasticizers. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Morphology and properties of PVC/clay nanocomposites via in situ emulsion polymerization

PVC/Na⁺–montmorillonite (MMT) nanocomposites were prepared via a simple technique of emulsion polymerization at several different MMT clay concentrations. X‐ray diffraction and transmission electron microscopy studies revealed the formation of a mixture of intercalated and exfoliated nanostructure. Tensile testing results showed that the tensile modulus of the nanocomposites increased with the addition of clay, while the tensile strength decreased little. The notched impact strength of the nanocomposites was also improved. For systems containing clay in the range of 2.1 to 3.5 wt %, the impact strength was almost two times as large as that of pure PVC. However, those mechanical properties began to decrease with the continuously increasing amount of clay. The fracture surface of pure PVC and the nanocomposites was observed by scanning electron microscope. Thermal properties of the nanocomposites were found to increase as a result of clay incorporation. The glass transition temperatures of the PVC/clay nanocomposites were nearly identical to that of pure PVC. The Vicat softening points exhibited a progressively increasing trend with the clay content added. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 277–286, 2004     

Synthesis and characterization of biobased polyester PVC plasticizers to industrial manufacturing of tubes

The search for the substitution of phthalate derivatives in the process of polyvinyl chloride (PVC) plasticization is a matter of intensive research, due to the increasing proofs about phthalate toxicity. With this objective, a series of novel saturated polyesters (SPs) were synthesized by polycondensation from different biobased acids and diols, and end-capped with 2-tetradecyloctadecan-1-ol (TDOD). After characterization, the SPs were incorporated in an industrial formulation for flexible PVC and the mechanical properties of the films analyzed by tensile tests, DMTA, and DSC. The tensile tests revealed a similar ultimate tensile strength and a higher elongation at break for the PVC with SP as plasticizers compared with DEHTP (di[2-ethylhexyl] terephthalate). The SP showing the most promising results was chosen to carry on an industrial manufacturing of a transparent tube. The migration tests of the tube show a much less leaching properties compared with tube prepared using the plasticizer DEHTP. All the results indicate that SPs can be an industrially viable and excellent alternative to DEHTP.     

Behavior of flexible poly(vinyl chloride)/poly(hydroxybutyrate valerate) blends

Blends of flexible poly(vinyl chloride) (PVC) and a poly(hydroxybutyrate valerate) (PHBV) copolymer were prepared and characterized with different techniques. The tensile strength of PVC did not show a marked reduction at PHBV concentrations up to 50 phr, despite a lack of miscibility between the two polymers. The crystallization of the PHBV copolymer was markedly hindered by the presence of PVC, as calorimetric results revealed. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

A new strategy for plasticizing and stabilization of PVC mixtures

This study was undertaken to examine possible use of classic tetravalent tin‐based heat stabilizers for the preparation of a polymer plasticizer: poly(ε‐caprolactone) (PCL) and simultaneous stabilization of PVC in PVC/PCL mixtures. PCL was prepared from ε‐caprolactone (CL) by polymerization initiated by tin‐containing organic compounds and successfully used to simultaneously plasticize and stabilize PVC. Moreover, conditions under which the polymerization of CL took place directly in situ during PVC/CL mixture processing were found. The procedure yielded homogeneous plasticized PVC/PCL mixtures, which were stable and contained >90% of the original monomer content. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 41066.     

Statistical thermal stability of PVC

Experimental design was used to optimize the processing parameters for the decomposition of poly(vinyl chloride). Factorial design and face centered composite design (FCC) were applied to determine the optimum conditions. A total of 10 g PVC powder was mixed with different amounts of zinc stearate (ZnSt₂) and natural zeolite and tested for thermal stability. Factorial fitted model was explained by first order pattern due to the significant main effect regression constants, and FCC model was described by second order model owing to higher order polynomial coefficients. FCC design was superior to factorial design as FCC considers not only its pure quadratic effects contribution but also its higher overall desirability for thermal stability of PVC. For factorial design the optimum conditions were determined as 163.06 mg for ZnSt₂, 399.99 mg for zeolite, and 140°C for temperature with desirability of 0.933. However, 400 mg for ZnSt₂, 333.24 mg for zeolite, and 140°C for temperature with desirability of 0.956 were obtained as the optimum conditions by FCC design. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Degradation kinetics of PVC plasticized with different plasticizers under isothermal conditions

The aim of the present work is to elucidate the degradation kinetics of polyvinyl chloride (PVC) plasticized with some phthalate and nonphthalate plasticizers. A PVC thermomat instrument was utilized to maintain the isothermal degradation conditions at 140 and 160°C, and to suppress the oxidative degradation by means of nitrogen flow. The conductivity measurements were performed to follow hydrogen chloride (HCl) gas which is released upon PVC degradation and trapped in water. Dehydrochlorination of plasticized PVC films occurred with activation energies of about 23–160 and 26–117 kJ mol^?1 and the isokinetic temperatures, at which the dehydrochlorination rate constants of all p‐PVC films would have the same value, were found to be 171 and 128°C for initial and linear regions of dehydrochlorination curve, respectively. Plasticizer incorporation contributes to the stability of the films particularly after the consumption of stabilizer due to the dehydrochlorination. Influence of temperature rise by 20°C on the degradation rate constant is the lowest for DINCH having p‐PVC films as 0.36 and 0.42% increment at the initial region and linear region, respectively. On the other hand, DOTP reveals greater stability than the others do since the compensation ratio of the PVC film having DOTP is greater than the other films. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41579.