Plasticizer factors influencing take-up by PVC resins

The ease with which plasticizer is combined with poly(vinyl chloride) resin is a measure of processing characteristics critical in the dry blending of suspension PVC and the gelation of plastisols. By using commercial grade plasticizers, this study developed predictive equations for the following processing parameters of dialkyl phthalates in PVC:

• Relative dry-blend rates in suspension PVC as a function of plasticizer viscosity.
• Relative initial gelation temperatures in plastisols as a function of plasticizer molecular weight and solvating strength.
• Relative final gelation temperatures in plastisols as a function of plasticizer solvating strength.

This information allows one to predict the relative processing characteristics of any dialkyl phthalate plasticizer for PVC on the basis of its chemical and physical properties.     

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     

Particle/plasticizer relationship during dry blending

The time for a PVC resin to dry blend or to become a free flowing mix, when blended with a plasticizer in an elevated processing mode, is a common concern for manufacturers of flexible PVC products. The limiting factor in some processes is the dry blending cycle time. Longer dry blending times increase manpower and energy cost per mixer batch. Each flexible PVC compounder has some type of quality control test he uses to assess a resin's dry-up properties. This paper examines the relationship of resin particles and plasticizer during dry-up testing of intermediate to high molecular weight PVC resins. Through this examination, a better understanding of the factors that control dry-up times was achieved. Also included is a comparison of quality control dry-up times and mix cycle times in production size mixers.     

Viscosity aging of poly(vinyl chloride) plastisol: The effect of the resin type and plasticizer type

The viscosity of freshly prepared poly(vinyl chloride) (PVC) plastisol increases with time, and this phenomenon is called viscosity aging. The increase is rapid in the beginning and slows down to a quasistable value, but a very slow increase continues. The phenomenon may be a result of either the deagglomeration of agglomerated particles or the dissolution of low‐molecular‐weight PVC into the plasticizer. In this work, two typical commercial resins were used, one containing friable agglomerates and the other containing nonfriable agglomerates. With the friable‐agglomerate resin, about 40% of the initially present agglomerates deagglomerated, whereas the viscosity increased in a week to twice the initial value. With the nonfriable‐agglomerate resin, very fine and very low molecular weight particles, about 3% of all the particles, dissolved into the plasticizer in 2 days. The effect of the plasticizer type on the viscosity aging through deagglomeration was investigated with four plasticizers and three plasticizer blends. The emulsifiers used for polymerization, and retained through drying, affected the aging in the beginning. On the other hand, the viscosity after 1 week was free from the effect of the emulsifier and was affected only by the plasticizer type. With the exception of two blends, the 1‐week viscosity was quantitatively related to the dielectric constant divided by the molecular weight of the plasticizer. For the plasticizer blends, one of the plasticizers could have a dominant effect on the promotion of deagglomeration. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 95: 448–464, 2005     

Prediction of plasticizer solvency using hansen solubility parameters

The solvating strength of a plasticizer for poly(vinyl chloride) resin is a measure of the interactive forces between these two materials. Hansen's three-dimensional solubility parameters provide a quantitative measure of these interactive forces. By using CO-ACT^SM service, a computer program designed for solvent systems with various resins, plasticizers were found to lie near the edge of the solvency “sphere” of PVC. The relative positions of various plasticizer structures are in the expected order, while known solvents show strong association and lubricating additives fall outside the solvency sphere of PVC.     

Fusion behavior of plastisols of PVC studied by ATR-FTIR

The behavior of PVC plastisols during gelation and fusion was studied by the ATR-FTIR technique (Attenuated Total Reflectance-Fourier Transform Infrared Spectroscopy). DBP, DOP, and DIDP, three common phthalate plasticizers for PVC, were used in plastisols formulations. Three heating rates—5, 10 and 15°C/min—and formulations with different plasticizer concentrations were studied. The IR spectra of a plastisol coincides with the IR spectra of the plasticizer except for the bands at 1435 and 613 cm^?1 from the PVC (CH₂ wagging and C—Cl stretching, respectively). When the plastisol is heated, a progressive decrease of the plasticizer bands areas can be observed, while bands from PVC increase their intensity, probably because of the adsorption of the plasticizer by the resin. On cooling, the area of all bands follows the same path as when heating, but the paths separate at a certain temperature, showing the irreversible nature of this process. The analysis of the band at 1280 cm^?1 (C(O)—O from plasticizer) during heating and cooling, shows that the temperature of separation areas (T_s) takes place at temperatures coherent with plasticizer compatibility. Studies at different heating rates and different plasticizer content are in good agreement with results using other techniques, available in the literature.     

Absorption of trioctyl trimellitate into mass‐polymerization and suspension‐polymerization poly(vinyl chloride)

Poly(vinyl chloride) (PVC) slush powder has been widely used; we prepared it by dry blending. We found that the absorption of plasticizer by the PVC resins was the most important factor in the dry‐blending process and, further, that different types of PVC resin had different absorption rates. This results of this study provide new information about the relationship of absorption to PVC and other parameters. Haake rheomix testing and the quantity of plasticizers absorbed by the PVC resins were used to characterize the absorption process. Suspension‐polymerization poly(vinyl chloride) (SPVC) and mass‐polymerization poly(vinyl chloride) (MPVC) in different sizes were used for the test. The results showed that the MPVC absorbed the plasticizer more quickly than SPVC, especially at a higher temperature. However, for the same PVC resin type, the absorbing speeds were nearly independent of particle size. The studies that used a scanning electric microscope and specific surface area revealed that the morphology of the two types of particles was different. The surfaces of the individual particles of SPVC were smoother than those of MPVC. There was a “skin” covering the SPVC particles, whereas with the MPVC particles, the primary polymer was exposed directly on the surface. This difference in morphology was shown to be a significant factor in the different rates of absorption of the plasticizers for the different PVC resins. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 2369–2374, 2004     

Energy and material cost savings with polyester/monomeric plasticized PVC compounds

Many plasticized PVC articles are exposed to harsh environments that cause loss of plasticizer through extraction, volatility, or migration. In order to survive in these applications, the PVC must contain plasticizers that have a reasonable degree of permanence. Two approaches are the use of low molecular weight polyester plasticizers, or higher molecular weight polyester/monomeric plasticizer blends. The blend approach can give better cost-performance and, due to faster fusion, reduced energy/manufacturing costs. The blends maintain their advantages even upon further dilution with monomeric plasticizers and in permanence tests of long duration. Although better than monomeric plasticizers, neither the low molecular weight polyester nor the blend system is recommended for applications requiring the ultimate in migration resistance.     

Influences of diallyl phthalate as chain extender on the properties of high molecular weight poly(vinyl chloride) resin

A higher porosity with better thermostability is desirable for poly(vinyl chloride) (PVC) resin. In this study, high molecular weight PVC resins are prepared by vinyl chloride monomer (VCM)‐diallyl phthalate (DAP) suspension copolymerization in a 20‐L reactor at 50 °C using DAP as chain extender. SEM, BET, and analyses of plasticizer absorption results show the high molecular weight poly(vinyl chloride) (HPVC) by DAP‐VCM copolymerization is loose and porous. With increasing DAP content when the mass ratio of DAP/VCM (ω) is below the gel point, the porosity and the degree of polymerization increase. Nevertheless, the bulk density and particle size decrease. When more than the gel point, these relationships are reversed. Thermogravimetric analysis revealed that the HPVC had better thermostability than that of commercial PVC, and its thermostability increases with increasing ω before it reaches the gel point. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45093.     

The fusion characteristics of PVC-plasticizer mixtures

Dry blends of a PVC resin with various plasticizer mixtures were processed at different temperatures to produce samples of different degrees of fusion. The ease of fusion increased with decreasing the solid-gel transition temperature (Tm) of the plasticizer mixture. Nevertheless. Tm was not necessarily a linear function of the individual concentration of plasticizers in the mixture. Therefore, the ease of fusion showed in some cases an optimum at a given concentration of the plasticizer mixture.     

Plasticizer diffusion as the rate-determining step in dry blending of poly(vinyl chloride)

Differential thermal analysis has been used to examine the process of dry blending of plasticizer and PVC. The rate of transformation of the glass transition from that of the polymer initially in the cold mix to the glass transition of the blend (blend T_g) has been examined at various temperatures from room temperature to above the polymer T_g. The dependence on temperature of this rate of transformation of the observed T_g is similar to the temperature dependence of the diffusion of plasticizer into PVC. It is concluded that diffusion of plasticizer into polymer particles is the rate-determining step in the dry blending of PVC. It also appears that a single mechanism of diffusion is involved both below and above the glass transition of the polymer.     

Synthesis and evaluation of dioctyl 2,5-thiophenedicarboxylate as a potentially bio-based plasticizer for poly(vinyl chloride)

In this work, dioctyl 2,5-thiophenedicarboxylate (DOT), a potentially bio-based plasticizer, was synthesized and evaluated as an alternative to traditional petroleum-based plasticizers. The chemical structure of DOT was confirmed by FTIR and ¹H NMR. Besides, its plasticization effect on poly(vinyl chloride) (PVC) was investigated in detail, and dioctyl 2,5-furandicarboxylate (DOF) as well as dioctyl isophthalate (DOIP) with similar chemical structures were used as references. The DMA results showed that the glass transition temperature (T_g) of PVC/DOT, PVC/DOF, and PVC/DOIP was 45.1°C, 33.6°C, and 51.3°C, respectively, indicating that the plasticizing efficiency of DOT was better than that of DOIP but lower than that of DOF. However, the tensile test results exhibited that the elongation at the break of PVC/DOT was higher than that of PVC/DOF, which was attributed to the easy phase separation between DOF and PVC. In addition, DOT displayed the best volatility resistance and exudation resistance among the three plasticizers, attributed to its highest molecular weight. Moreover, the migration loss of DOT in non-polar solvents was much smaller than that of DOIP because of its stronger molecular polarity. In conclusion, DOT has good potential to replace traditional petroleum-based plasticizers and be used as a primary plasticizer for PVC.     

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.     

Rheometric study of the gelation and fusion processes of poly(vinyl chloride‐co‐vinyl acetate) plastisols with different commercial plasticizers

Evolution of the complex viscosity of pastes of PVC‐VA (vinyl chloride‐vinyl acetate copolymer) plasticized with different commercial plasticizers has been studied. Knowledge of the rheological behavior of the formulations allows for better understanding of the gelation and fusion processes. Twenty commercial plasticizers of different types and with different functional groups have been studied and are grouped into five families: phthalate esters with linear chains, phthalate esters with branched chains, adipates (normal and polymeric), citrates, and rest of the plasticizers (carboxylates, alkylsulfonates, and pentaerythritol ester derivatives). Interesting relationships among the observed rheologies and the nature and molecular weight of the plasticizer have been observed. The evolution of the complex viscosity with temperature—at the temperatures where the blowing agents normally used in PVC plastisol foaming processes generate the main amount of gas—has been newly discussed with regard to the chemical structure and molecular weight of all of the plasticizers used. It was found that several different dynamic processes must be synchronized in order to understand the relationships among the chemical structure, plasticization, plasticizer compatibility, rheological properties, and foaming process of such materials. J. VINYL ADDIT. TECHNOL., 2012. © 2012 Society of Plastics Engineers     

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.     

Dialkyl furan‐2,5‐dicarboxylates,epoxidized fatty acid esters and their mixtures as bio‐based plasticizers for poly(VInylchloride)

Dialkyl furan‐2,5‐dicarboxylates and epoxidized fatty acid esters (EFAE) of varying molecular weights and volatilities, as well as their mixtures, were investigated as alternative plasticizers for poly(vinylchloride) (PVC). The EFAE utilized were epoxidized soybean oil (ESO) and epoxidized fatty acid methyl ester (e‐FAME). All plasticizers were compatible with PVC, with plasticization efficiencies usually increasing with decreasing molecular weights of the plasticizers (except in the case of ESO, which was remarkably effective at plasticizing PVC, in spite of its relatively high molecular weight). In comparison with phthalate and trimellitate plasticizers, the alternatives generally yielded improved balance of flexibility and retention of mechanical properties after heat aging, with particularly outstanding results obtained using 30?50 wt % e‐FAME in mixtures with diisotridecyl 2,5‐furandicarboxylate. Although heat aging characteristics of the plasticized polymer were often related to plasticizer volatilities, e‐FAME performed better than bis(2‐ethylhexyl) 2,5‐furandicarboxylate, and bis(2‐ethylhexyl) phthalate of comparatively higher molecular weights. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42382.     

Effect of the phase ratio on the particle properties of poly(vinyl chloride) resins produced by suspension polymerization

The effects of the dispersed phase to continuous phase ratio (weight of VCM (gr)/weight of water (gr) (φ = g_VCM/g_water)) on the particle properties of a poly(vinyl chloride) (PVC) suspension were investigated experimentally. A series of experiments were performed with different φ values in a pilot‐scale reactor. The cold plasticizer absorption of the resin decreased with φ. Scanning electron micrographs showed that by the reduction of φ, many of the produced particles had a regular shape, a smooth surface, and greater porosity. An increase in φ caused a wider and multimodal particle size distribution of the produced PVC particles. The mean particle size and bulk density also increased with φ, whereas the molecular weight and polydispersity index did not change. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Synthesis and evaluation of epoxidized vegetable oleic acid as a novel environmental benign plasticizer for polyvinyl chloride

A bio-based plasticizers, acetyl-oleate triethylene glycol (AOT), was successfully synthesized by using oleic acid as a raw material through esterification, epoxidation, and acetylation. Its structure was analyzed by Fourier transform infrared spectroscopy and ¹H nuclear magnetic resonance. The plasticizing performances of this plasticizer was compared with those of two commercial ones: dioctyl terephthalate (DOTP) and dioctyl adipate (DOA). This was done by blending these plasticizers with PVC, respectively. Thermal gravimetric analysis results showed that the 5% weight loss temperature of PVC with AOT was 53°C higher than that of DOA and 36°C higher than that of DOTP. The tensile results showed that the AOT plasticized PVC had excellent stretchability: its elongation at break with 50 phr AOT reached 697.7%. Furthermore, its transmittance was as high as 90%, showing better compatibility of ATO with PVC.     

多功能植物油基增塑剂制备及增塑PVC研究进展

植物油基增塑剂因具有原料来源广、结构可调、增塑性能优良、无毒和可生物降解等优点,被认为是最具应用前景的生物基环保增塑剂。然而,植物油基增塑剂结构中长链烷基比重过高,导致其与PVC树脂相容性较差,通常作为辅助增塑剂使用,应用价值未得到有力彰显。近年来,国内外学者对植物油基增塑结构进行化学改性,开发了系列多功能植物油基增塑剂(如增容、耐热、阻燃、耐迁移等),实现了植物油基增塑剂的“提质增效”。本文从植物油分子结构设计出发,通过分子模拟、微观和宏观分析手段相结合的方式对现有文献进行归纳、分析和总结,建立了增塑剂结构和增塑后PVC制品性能的“构效”关系,旨在为高性能、多功能植物油基增塑剂的结构设计和工业化生产提供理论依据。     

环保聚氯乙烯增塑糊凝胶性能的研究

采用转矩流变仪和旋转黏度计研究了PVC树脂种类、增塑剂种类、掺混树脂加入量对环保PVC增塑糊凝胶性能的影响规律。结果表明,PVC糊树脂聚合度越大,增塑糊的凝胶化时间越长;颗粒呈规则圆状树脂配制的增塑糊,其凝胶时间相对较长;颗粒呈扁片状的树脂配制的增塑糊,其凝胶时间相对较短。增塑剂与PVC糊树脂相容性越差,增塑糊的凝胶时间越长。随掺混树脂添加量的增多,凝胶时间逐渐延长,当其加入量为40 份（质量份,下同）时,凝胶时间从空白时的18 min延长至28 min。