Application of Fourier transform infrared spectroscopy in the study of interactions between PVC and plasticizers: PVC/plasticizer compatibility versus chemical structure of plasticizer

Fourier transform infrared spectroscopy is applied in the study of interactions between PVC resin and plasticizers in flexible PVC systems. The comparison of the theoretical infrared spectra coming from the addition of the respective component infrared spectra with those of PVC/plasticizer experimental systems gives information about polymer/plasticizer interaction degree. In addition, solvation capacity of the plasticizer varies as a function of its chemical structure, giving rise to compatibility differences between the system components. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1731–1737, 2006     

Palm oil‐based compound as environmentally friendly plasticizer for poly(vinyl chloride)

Many plasticizers have been invented to serve the purpose of making poly(vinyl chloride) (PVC) into a more flexible plastic. In this work, the potential of palm oil‐based compound (Palm1) as a polymeric plasticizer for PVC was investigated. Plasticization of PVC was conducted via the solvent casting technique, using tetrahydrofuran (THF) as the mutual solvent. Fourier transform infrared (FTIR) spectroscopy and differential scanning calorimetry (DSC) were used to find evidence of interactions between the plasticizer and PVC. Transition temperatures (T_gs) of the plasticized PVC were obtained using DSC, and their thermal stabilities were evaluated using a thermogravimetric analyzer (TGA). Results from the study show that the polymeric plasticizer could interact with PVC chains via polar interaction involving –C‐Cl of PVC and possibly the ‐OH groups of Palm1. T_g of the PVC was reduced after it was plasticized with Palm1. The results obtained from this study suggest that the Palm1 may have the potential to serve as an environmentally friendly plasticizer for PVC. J. VINYL ADDIT. TECHNOL., 22:80–87, 2016. © 2014 Society of Plastics Engineers     

Plasticizer compatibility testing: Dynamic mechanical analysis and glass transition temperatures

Plasticizer compatibility with the polymer, which implies that plasticizer and polymer will remain closely associated as the finished polymer product is used, is critically important in determining whether a flexible poly(vinyl chloride) (PVC) product will have an acceptably long service life. However, with traditional test methods, it is often difficult to distinguish degrees of compatibility among relatively compatible ingredients (ingredients that do not dissociate themselves from the polymer in a very short time or under very mild storage conditions). Dynamic mechanical analysis is a commonly used technique for measuring glass transition temperatures, which can be a useful property in comparing additives' compatibilities. Unlike many polymers, flexible PVC shows two glass transition temperatures, one for the polymer segments that show syndiotactic (but noncrystalline) stereochemistry, and one for the polymer segments that show atactic stereochemistry. The glass transition temperature for the atactic segments of flexible PVC provides some information about the plasticizer's compatibility. When the dynamic mechanical analysis temperature sweep for a plasticized PVC compound detects a particularly low glass transition for the atactic polymer segments, this can be an indication that the plasticizer is relatively incompatible with the PVC. J. VINYL ADDIT. TECHNOL., 21:7–11, 2015. © 2014 Society of Plastics Engineers     

Plasticized poly(vinyl chloride) composites: Influence of different nanofillers as antimigration agents

In this study, plasticized poly(vinyl chloride) (PVC) composites with different nanofillers, including single‐walled carbon nanotubes (SWCNTs), organoclay, TiO₂, and ZnO nanoparticles, were prepared, and their effects on plasticizer migration were investigated. Scanning electron micrographs revealed the dispersion quality of the nanofillers in the polymer matrix. It had a significant influence on the performance of the nanofillers in the process of plasticizer migration. Migration and exudation tests showed that the nanofillers could efficiently hinder plasticizer migration. On the basis of these results, we concluded that carbon nanotubes were the best antimigration agent in the plasticized system. This was ascribed to the high aspect ratio of the SWCNTs and the good interactions between them and the plasticizer. Also, TiO₂ nanoparticles showed a better performance compared to the ZnO nanoparticles. This was due to the more homogeneous dispersion of the TiO₂ in the polymer matrix and the higher surface area of the particles. The differential scanning calorimetry thermograms were in good agreement with the migration tests. The lowest change in the glass‐transition temperature was observed for the composite filled with SWCNTs. This indicated that a lower amount of the plasticizer migrated from PVC. The thermogravimetric analysis curves showed that the incorporation of the nanofillers improved the thermal stability of the PVC. The results could be useful for determining the efficiency of plasticized PVC in applications. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42559.     

Plasticizer migration from cross‐linked flexible PVC: Effects on tribology and hardness

Uses of flexible poly(vinyl chloride) (PVC) are restricted by plasticizer migration affecting material properties. Moreover, the use of phthalate‐based plasticizers is being questioned worldwide because of their potential toxicity to humans and environment. Chemical modification of PVC structure is one of the most effective tools for reduction of plasticizer diffusion. In this work, a flexible dry blend based on cross‐linked PVC was obtained using a difunctional amine, namely isophoron diamine (IPDA) as the cross‐linking agent. The gel fraction was evaluated from insoluble portions obtained by means of solvent extraction; the efficiency of cross‐linking in reducing the plasticizer leaching was evaluated by migration tests. Effects of addition of IPDA on PVC thermal stability were determined by thermogravimetric analysis (TGA). The cross‐linking reaction turned out to be responsible for accelerating thermal degradation. Tribological properties of flexible uncross‐linked, cross‐linked and rigid PVC were determined. Flexible formulations were held in contact for 32 days with rigid PVC sheets. Plasticizer migration towards the interface caused an increase of dynamic friction compared to that of the reference rigid PVC.Vickers microhardness h_Vickers values of rigid PVC sheets decreased due to plasticizer surface absorption. POLYM. ENG. SCI., 2012. © 2011 Society of Plastics Engineers     

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.     

A novel route of synthesis,characterization of terephthalic dihydrazide from polyethylene terephthalate waste and it's application in PVC compounding as plasticizer

The degradation of polyethylene terephthalate (PET) waste by making use of hydrazine monohydrate was investigated at ambient temperature and pressure. The aminolysed end products obtained were characterized with chemical tests and spectroscopic techniques namely IR, UV‐visible spectroscopy and NMR, and the differential scanning calorimeter (DSC). The end product was characterized as terephthalic dihydrazide (TPD) and further used in PVC compounding as secondary plasticizer. The hardness, tensile strength, elongation at break, thermal stability, and compatibility of the PVC sheet were studied and concluded that the aminolysed product may find potential application as secondary plasticizer in PVC formulations. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Study of the preparation of plasticized PVC with a surface with barrier properties

Plasticized PVC sheets are often used in packaging for blood or liquid foods, as well as cosmetics or solvents. Two matter transfers may take place: the liquid entering the PVC, and the plasticizer leaving the solid. These transfers are detrimental to the polymer, which becomes less flexible, and to the liquid, which is polluted. A two-step process for preparing plasticized PVC samples with low matter transfers is studied. The polymer is immersed into a liquid for a short time and then dried. At the end of the process, a steep gradient of concentration is obtained next to the PVC surface both for the plasticizer and the liquid, with a low concentration on the surface. As the process of transport is controlled by diffusion with concentration-dependent diffusivities, very low initial rate of transport is obtained for the final PVC. Models based on numerical methods with finite differences are used in order to describe the process and provide a fuller insight of its mechanism.     

An innovative plasticizer for sensitive applications

Di(isononyl) cyclohexane‐1,2‐dicarboxylate (HEXAMOLL® DINCH) is a new plasticizer for PVC. In the tests used, it has no indication of toxicity or genotoxicity; it is biodegradable; and it has low sensitizing properties. Its properties in PVC compare favorably to those of other plasticizers having well‐balanced properties. This plasticizer should be well‐suited for sensitive applications.     

DSC study of foamable poly (vinyl chloride‐co‐vinyl acetate) plastisols of different commercial plasticizers

In this article the characterization of the thermal behavior of foamable PVC (Poly (vinyl chloride)) plastisols from 20 different plasticizers has been studied by differential scanning calorimetry (DSC). The interactions between the resin and the plasticizer as well as the decomposition of the azodicarbonamide (ADC)—the chemical blowing agent (CBA) used—have been analyzed. The latter process is of crucial importance for the knowledge of plasticized PVC flexible foam formation. Clear effects of the chemical nature of the plasticizers and their molecular weight (M_w) have been observed, both in the interactions (swelling and early stages of gelation) between the resin and the plasticizer, as well as in the temperature of the ADC decomposition and the shape of the DSC peak. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Kinetics of absorption of N-alkyl phthalate plasticizers into PVC resin particles

The kinetics of plasticizer absorption by suspension polymerized polyvinylchloride (PVC) have been investigated. The volume swelling ratios of individual PVC particles, immersed in excess plasticizer, were recorded over a period of time using an optical microscope equipped with a high speed camera, Absorption of din-decylphthalate was studied in the range 70 < T < 100°C. The study shows that the uptake of plasticizer proceeds in three steps: (1) a slow initial absorption into glassy PVC, which is a thermally activated rate process, wherein the polymer is being progressively solvated and evolving toward the rubbery state, (2) the considerable faster diffusion of plasticizer into a rubbery, dynamic polymer matrix, and (3) the asymptotic approach to the equilibrium swelling capacity. Temperature dependency of rate of absorption in the slow initial step was fitted to an Arrhenius expression, and an activation energy for plasticizer uptake was calculated.     

Contributions to characterization of poly(vinyl chloride)–lignin blends

The present study evaluates the impact of blending organosolv and kraft lignins, which are natural polymer by‐products in the pulp and paper industry, with plasticized poly(vinyl chloride) (PVC) in flooring formulations. Also examined is the impact of replacing dioctyl phthalate, a PVC industry general‐purpose plasticizer, with diethylene glycol dibenzoate (Benzoflex 2‐45), tricresyl phosphate (Lindol), or alkyl sulfonic phenyl ester (Mesamoll) in these formulations. The influence of the different types of lignins and plasticizers on the processibility, thermal, and mechanical properties of the blends is discussed. These properties demonstrate that partial replacement of PVC (20 parts) with different lignins is feasible for some formulations that can be successfully used as matrices for a high level of calcium carbonate filler in flooring products. In addition, the data demonstrate that the presence of certain plasticizers, which interfere with the intramolecular interactions existing in lignins, may allow the lignin molecules to have more molecular mobility. The morphology and the properties of PVC plasticized lignin blends are strongly influenced by the degree and mode of the lignin plasticization and its dispersion within the PVC matrix. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 2732–2748, 2006     

Compatibility of plasticizers with poly(vinyl chloride)

The tendency of a plasticizer to resist exudation from poly(vinyl chloride) (PVC) under compressive stress, known technologically as “compatibility,” is treated in terms of a network model, the plasticized composition being thought of as a rubber crosslinked by crystallites. Compatibility is increased by increased solvency (Flory-Huggins χ) and decreased by increasing plasticizer molar volume. A large crosslink density and/or insufficient melting of crosslinks during processing (thermal history) also decreases compatibility. All commercial primary plasticizers are believed to be infinitely miscible with amorphous PVC. Phase separation which occurs is syneresis and not related to any phase diagram. Swelling tests for compatibility and swelling measurements on dilute PVC gels are described. Some general principles relating to gel formation and association in polymer solutions are also discussed.     

Improving the receptivity of PVC articles toward water-based inks,coatings, or adhesives

Typically, the measure of hydrophobicity in PVC films and sheets is a surface energy measurement in dynes/cm in the low-to-mid thirties. More recently, the trend has been to lower the amounts of solvents used in inks, coatings, and adhesives, which, in turn, are used to coat or print the flexible PVC article. With the change in the makeup of coating systems, a modification in the surface energy of the flexible PVC film is needed to make an inherently hydrophobic material more hydrophilic. It has been found that the combination of a polymeric plasticizer and a monomeric plasticizer in conjunction with a metal oxide, unexpectedly increases the hydrophilicity of PVC sheets or films by factors of roughly 25% to 33%. This paper discusses the results of an investigation leading to an increase of surface tension from 33–36 dynes/cm to 40–43 dynes/cm.     

Weathering of plasticized poly(vinyl chloride)

A series of flexible plasticized poly(vinyl chloride) (PVC) compositions containing different organotin compounds and ultraviolet absorbers has been exposed for 4.5 years at four outdoor sites in Australia with widely differing climatic conditions. Loss of plasticizer by evaporation during the exposure was measured and an empirical correlation was found with the average daily maximum temperature at each site. The relative effectiveness of the organotin compounds and ultraviolet absorbers in preventing deterioration of the PVC was estimated by measuring the viscosity of the polymer after exposure. This method of assessment is compared with the results of mechanical tests on the specimens.     

Diester based on castor oil fatty acid as plasticizer for poly(vinyl chloride)

Castor oil is a renewable resource that has potential uses as an environmental friendly material for a range of applications. In recent years, much efforts have been driven to develop alternate plasticizer for medical and commodity plastics due to growing concerns about dioctyl phthalate (DOP) for flexible poly(vinyl chloride) (PVC). In this study, a bio‐based plasticizer was synthesized by a two‐step esterification reaction of castor oil fatty acid (COFA) with benzyl alcohol and octanoic acid in the presence of catalyst (dibutyl tin dilaurate). The structure of the octanoic ester (OE) was confirmed by proton nuclear magnetic resonance, Fourier transform infrared spectroscopy, acid value, and hydroxyl value. OE was used as a coplasticizer in PVC for partial replacement of DOP. The addition of OE exhibited good incorporation and plasticizing performance in the PVC sheets. Incorporation of OE resulted in good plasticizing, tensile strength, percentage elongation, exudation, thermal stability, and chemical resistance because of the presence of long carbon chains of COFA. Differential scanning calorimetry (DSC), thermogravimetric analysis, and color measurements were also performed to evaluate the effect of OE. With the increase in OE, DSC and hardness results showed marginal deviation from those obtained for DOP‐plasticized sheets. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40354.     

A comparative study of branched and linear dialkyl phthalate plasticizer surface levels and their effects on adhesive bonds in flexible PVC

A method has been developed to quantitatively measure the surface plasticizer levels present on test plaques made from a plasticized PVC compound. The plaque fabrication conditions have been chosen so that the plaque closely models an extruded flexible PVC profile. The analysis method utilized sorption of the surface plasticizer on fumed silica, followed by methanol extraction and liquid chromatographic identification and quantitation of the plasticizer. Typical results are presented for a model compound plasticized with either di-2-ethylhexyl phthalate (DOP) or a mixture containing predominantly linear C₇, C₉, and C₁₁ dialkyl phthalates (DHNUP). The effect of compound work level, as measured by Banbury drop temperature and final processing temperature, has also been studied. These results show that, for the model compound studied, the average surface level of DHNUP is always greater than that of DOP. The DOP levels are essentially independent of compound work level. The DHNUP levels generally increase with increasing mold temperatures. Finally, this data has been correlated with a study of the lifetime of a Neoprene-based adhesive bond to DOP-and DHNUP-plasticized flexible PVC in a 100°C oven. These studies clearly show that a one-to-one substitution of DOP for DHNUP will increase the time to adhesive bond failure by a factor of at least 10 with this particular adhesive system and model compound.     

Viscoelastic characterization of PVC plastisol melts for foam applications

Melt rheology and its time-temperature dependence have long been known to be fundamental properties associated with satisfactory expansion characteristics in vinyl foam. Since much is known about the relationship between rheology and material variables like polymer morphology and system composition, adequate rheological characterization should be quite helpful in polymer design and plastisol compounding. Earlier attempts to study the melt rheology of plasticized PVC foam systems were only partially successful because instrument limitations required that the material be studied at too high shear rate or temperature, or that behavior of specific compositions be extrapolated from data obtained at considerably higher plasticizer level. This paper deals with measurement of the viscoelastic behavior of melts from actual azodicarbonamide foam compositions. The Rheometrics Mechanical Spectrometer was used in the orthogonal mode to study both elastic modulus and loss modulus (viscosity) in the range of shear rates and temperatures which actually occur during commercial utilization of PVC foam compounds. The effects of changing vinyl resin types and plasticizer types and levels were explored.     

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.     

Properties of poly(vinyl chloride) incorporated with a novel soybean oil based secondary plasticizer containing a flame retardant group

A novel bio‐based plasticizer containing flame retardant groups based on soybean oil (SOPE) was synthesized from epoxidized soybean oil (ESO) and diethyl phosphate through a ring‐opening reaction. PVC blends plasticized with ESO and SOPE were prepared, respectively. Properties including rheological behavior, thermal stability, flame retardant performance, mechanical properties of PVC plasticized with ESO and SOPE were carefully studied. The results showed that the plasticized PVC blends indicated better compatibility, thermal, and mechanical properties. As a novel bio‐based plasticizer containing flame retardant groups, the TGA data indicated that the thermal degradation temperature of PVC blends plasticized with SOPE could reach to 275.5°C. LOI tests and SEM indicated that the LOI value of PVC blends could increase from 24.2 to 33.6%, the flame retardant performance of SOPE was put into effect by promoting polymer carbonization and forming a consolidated and thick flame retardant coating quickly, which is effective to prohibit the heat flux and air incursion. The enhancement in flame retardancy will expand the application range of PVC materials plasticized with SOPE. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42111.