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.     

Synthesis and application of a natural plasticizer based on cardanol for poly(vinyl chloride)

A natural plasticizer with multifunctional groups, similar in structure to phthalates, cardanol derivatives glycidyl ether (CGE) was synthesized from cardanol by a two‐step modification process and characterized by FT‐IR, ¹HNMR, and ¹³CNMR. The resulting product was incorporated to PVC (CGE/PVC), and plasticizing effect was compared with PVC incorporated with two kinds of commercial phthalate ester plasticizers bis (2‐ethylhexyl) benzene‐1,4‐dicarboxylate (DOTP) and diisononyl phthalate (DINP). Dynamic mechanical analysis and mechanical properties testing of the plasticized PVC samples were performed in order to evaluate their flexibility, compatibility, and plasticizing efficiency. SEM was employed to produce fractured surface morphology. Thermogravimetric analysis and discoloration tests were used to characterize the thermal stabilities. Dynamic stability analysis was used to test the processability of formulations. Compared with DOTP and DINP plasticized samples, CGE/PVC has a maximum decrease of 9.27% in glass transition temperature (T_g), a maximum increase of 17.6% in the elongation at break, and a maximum increase of 31.59°C and 25.31 min in 50% weight loss (T50) and dynamic stability time, respectively. The obtained CGE also has slightly lower volatility resistance and higher exudation resistance than that of DOTP and DINP. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42465.     

Ester‐amide based on ricinoleic acid as a novel primary plasticizer for poly(vinyl chloride)

Utilization of ricinoleic acid as a raw material for the synthesis of green plasticizer would offer an alternative to the phthalate plasticizers. Ester‐amide of ricinoleic acid was synthesized by a two‐step reaction with dibutyl amine and benzoic acid; and then utilized as primary plasticizer in PVC. Ester‐amide plasticizer was added up to 40 phr in PVC; and the prepared PVC sheets were characterized for mechanical, X‐ray diffraction, thermal, rheological, colorimetric, and exudation properties. Addition of the ester‐amide plasticizer demonstrated good incorporation and plasticizing performance in PVC. Viscosity of PVC decreased with increased addition of ester‐amide plasticizer. The dark color of the synthesized plasticizer could have constraints on its application areas; however, the prepared samples illustrated negligible weight loss in the exudation test, attributed to better compatibility between them brought about by the ester, tertiary amide and polarizable benzene ring in the ester‐amide plasticizer with the C‐Cl polar linkage in PVC. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41913.     

Synthesis and application of a novel thermostable epoxy plasticizer based on levulinic acid for poly(vinyl chloride)

Epoxy bisphenol acid isooctyl ester (EBAIE) was synthesized and characterized by FTIR and H-NMR. EBAIE was used as poly(vinyl chloride) (PVC) plasticizer for the first time, and its addition amount was 30 wt% of PVC. The mechanical properties, thermal stability, compatibility, and decomposition activation energy of PVC blends were systematically studied. Compared to the commercial plasticizer-dioctyl phthalate (DOP), the tensile strength had been significantly increased from 30.64 to 45.07 MPa, while the elongation at break had little difference. The thermal stability analysis showed that the static stability time at 180°C had been extended from 40 to 300 min. The decomposition activation energy indicated that the EBAIE plasticized PVC was with a higher thermal stability. The extraction and volatility resistance of the novel plasticizer were superior to those of DOP.     

Evaluation of the effects of biobased plasticizers on the thermal and mechanical properties of poly(vinyl chloride)

Blends were prepared of poly(vinyl chloride) (PVC) with four different plasticizers; esters of aconitic, citric, and phthalic acids; and other ingredients used in commercial flexible PVC products. The thermal and mechanical properties of the fresh products and of the products after 6 months of aging were measured. Young's modulus of the PVC blends was reduced about 10‐fold by an increase in the plasticizer level from 15 to 30 phr from the semirigid to the flexible range according to the ASTM classification, but a 40‐phr level was required for PVC to retain its flexibility beyond 6 months. At the 40‐phr level, tributyl aconitate performed better than diisononyl phthalate (DINP) or tributyl citrate, in terms of lowering Young's modulus, both in the fresh materials and those aged for 6 months. The effects of the four plasticizers on the glass‐transition temperature (T_g) were similar, with T_g close to ambient temperature at the 30‐ and 40‐phr levels in freshly prepared samples and at 40–60°C in those aged for 6 months. The thermal stability of the PVC plasticized with DINP was superior among the group. Overall, tributyl aconitate appeared to be a good candidate for use in consumer products where the alleged toxicity of DINP may be an issue. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 1366–1373, 2006     

Preparation of cardanol based epoxy plasticizer by click chemistry and its action on poly(vinyl chloride)

In recent years, the using of reproducible resource and economical and efficient synthesis method has got wide concern. Herein, an environmental‐friendly plasticizer originated from cardanol was synthesized by click chemistry. First, the cardanol sulfide (CS) was obtained by click chemistry reaction between the double bond of the side chain of cardanol and mercaptoethanol. The degree of the click reaction was estimated to reach 84.7% by testing the content of sulfur. Then, the epoxidation of the hydroxyl was performed to get cardanol based epoxy plasticizer (CEP) in the presence of epichlorohydrin. The epoxy value was 0.32. The structure of CS and CEP was confirmed by FT‐IR and NMR techniques. A Haake torque rheometer was used to research the action of CEP on polyvinyl chloride (PVC). Results showed that it possessed favorable plasticization effect and stabilization effect on PVC. CEP had good heat stabilization in PVC, and could decrease the T_g of PVC significantly. Moreover, CEP could increase the tensile strength of PVC when in a small amount, and could increase the plasticity of PVC when in a larger quantity significantly. The characteristics of volatile, migration and solvent extraction of PVC plasticized by CEP is similar to by dioctyl phthalate (DOP). © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44890.     

Biodegradable antistatic plasticizer based on citrate electrolyte doped with alkali metal salt and its poly(vinyl chloride) composites

An eco‐friendly citrate electrolyte‐based antistatic plasticizer (CEAP) consisting of sodium thiocyanate‐doped tris(2‐butoxyethyl) citrate was successfully synthesized using a typical esterification reaction between citric acid and 2‐butoxyethanol. Poly(vinyl chloride) (PVC)/CEAP composites were then prepared in a Haake torque rheometer. Fourier transform infrared spectroscopy was used to confirm both the structure of the synthesized CEAP and the coordination effects between the doping salt and CEAP. The dependence of the conductivity of the synthesized CEAP on temperature and concentration of the doping salt was investigated. The surface resistivity and mechanical properties of the PVC/CEAP composites were also studied. The results showed that the surface resistivity of the PVC/CEAP composites could be effectively reduced to the order of 10⁷Ω sq^?1 when the CEAP content reached 80 phr. The surface resistivity of the composites still reached 10⁸Ω sq^?1 even at a relative humidity of 12%, showing an excellent electrostatic discharge (ESD) capacity. The fabricated composites with good ESD capacity also had a tensile strength of 10 MPa and an elongation at break of 400%, which could satisfy requirements for packaging applications or similar usages. Copyright © 2010 Society of Chemical Industry     

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     

Alloying of poly(vinyl chloride) to reduce plasticizer migration

Concern over the migration of low molecular weight plasticizer from flexible poly(vinyl chloride) (PVC) used in toys and medical products has spearheaded the commercialization of a number of plasticizing polymers. In this study the plasticizing behavior of an ethylene/vinyl acetate/carbon monoxide terpolymer (Elvaloy® from DuPont) was investigated. Blends of PVC, Elvaloy 742, and dioctyl phthalate (DOP) were processed on a twin‐roll mill and compression molded into plaques. These materials were characterized in terms of their hardness, glass‐transition temperature (T_g), clarity, mechanical properties, and plasticizer migration behavior. The ratios of PVC/DOP/Elvaloy investigated were determined by experimental design. Using this approach it was possible to model the results and produce contour plots to map out the properties of a wide range of formulations. It was confirmed that Elvaloy 742 is compatible with PVC and has a plasticizing effect: this was demonstrated both in terms of a reduction in Shore A hardness and a reduction in T_g. Plasticizer migration was reduced in proportion to the amount of liquid plasticizer replaced. Plasticizing with Elvaloy gave an improvement in tear strength. However, at constant hardness there was no improvement in tensile strength from replacing DOP with Elvaloy. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 2022–2031, 2004     

Synthesis and application of a novel cardanol‐based plasticizer as secondary or main plasticizer for poly(vinyl chloride)

A novel plasticizer based on cardanol, hydrogenated cardanol glycidyl ether acetic ester containing phosphaphenanthrene group (HCGEP), was prepared and incorporated into poly(vinyl chloride) (PVC) for the first time. The molecular structure was characterized with Fourier transform infrared and ¹H NMR spectroscopies. The thermal degradation behavior and flame retardant performance of PVC films with HCGEP as secondary or main plasticizer were investigated using thermogravimetric analysis, combustion tests, limiting oxygen index tests and morphological analysis of residues. Furthermore, the mechanical properties of PVC films were examined based on the results of tensile testing. The results were compared to those of the petroleum‐based plasticizer dioctyl phthalate. With the substitution of dioctyl phthalate with HCGEP, PVC films exhibited high thermal stability and better flame retardant performance. The tensile test results showed that the addition of HCGEP could endow PVC resin with well‐balanced properties of flexibility, strength and hardness. © 2017 Society of Chemical Industry     

Design and synthesis of HFCA-based plasticizers with asymmetrical alkyl chains for poly(vinyl chloride)

A series of bio-based diester plasticizers with various alkyl chain asymmetry and the same molecular weight were designed and synthesized, using renewable 5-hydroxymethyl-2-furancarboxylic acid (HFCA) as the raw material. The chemical structures of the HFCA-based plasticizers were characterized by Fourier transform infrared and nuclear magnetic resonance (¹H NMR and ¹³C NMR). Besides, the influence of alkyl chain asymmetry on plasticization properties of the HFCA-based plasticizers in poly(vinyl chloride) (PVC) blends was also investigated. It was found that increasing the alkyl chain asymmetry of the diester plasticizer and keeping the molecular weight unchanged simultaneously could further improve its plasticizing efficiency, without sacrificing its volatility resistance and exudation resistance. The results showed that this study provided a new approach for further optimizing the overall properties of the asymmetric diester plasticizers.     

Effect of ketal group in castor oil acid-based plasticizer on the properties of poly(vinyl chloride)

Two castor oil acid esters containing a ketal or ketone group (KCL or CL), as alternative plasticizers for poly(vinyl chloride) (PVC), were prepared. The structures were confirmed by ¹H NMR and FTIR spectroscopies. The effects of the presence of a ketal or ketone group in these compounds on PVC plasticization were examined. The DMA and SEM results showed that both plasticizers were miscible with PVC and exhibited excellent plasticizing properties, compared to those of dioctyl phthalate (DOP). The PVC plasticized by KCL displayed a lower T_g value of 20.6 ° C, which was lower than that of PVC plasticized with DOP (22.3 ° C) and PVC plasticized with CL (40.5 ° C). Tensile tests indicated that PVC plasticized using KCL showed a 37% higher of elongation at break than PVC plasticized by CL and 30% higher than PVC plasticized by DOP. The plasticizing mechanism was also investigated. Moreover, exudation, volatility, and extraction tests, along with TGA indicated that the presence of ketal groups effectively improved the migration resistance of plasticizer and the thermal stability of PVC blends. Taken together, introducing ketal groups into plasticizer might be an effective strategy for improving its plasticizing efficiency.     

Compatibility of poly(vinyl chloride) with epoxidized copolymers of butadiene-styrene

The compatibility of poly(vinyl chloride) (PVC) with epoxidized styrene-butadiene copolymers is examined at different levels of epoxidation. The copolymers modified were a random (SBR) containing 45 wt% styrene and a triblock (SBS) with 30 wt% bound styrene. Blends were examined in the complete composition range and the approximate levels of epoxidation to ensure blend miscibility were determined. Epoxidized SBS (ESBS) was more effective in miscibility compared with ESBR requiring a lesser degree of epoxidation (43 versus 46 mol%). Tensile properties of the ESBS/PVC blends showed the efficiency of ESBS as a polymeric plasticizer even at levels of epoxidation (ca. 35 mol%) where immiscibility sets in.     

Synthesis and application of an environmental epoxy plasticizer with phthalate-like structure based on tung oil and cardanol for poly(vinyl chloride)

An epoxidized cardanol tungoleate (ECT) based on tung oil and cardanol was synthesized through esterification and epoxidation. The chemical structure of the compound was verified by Fourier transform infrared spectroscopy (FTIR) and proton nuclear magnetic resonance (¹H-NMR). The plasticizing effects of ECT as the main plasticizer in poly(vinyl chloride) (PVC) was studied and compared with the commercial plasticizer dioctyl phthalate (DOP). The thermal migration stabilities, the thermal degradation process and the mechanical properties of PVC samples and the plasticization mechanism of ECT for PVC were investigated through the use of volatility, extraction, discoloration, and tensile tests as well as thermal gravity analysis (TGA), TGA–FTIR analysis, electronic universal testing machine and dynamic mechanical analysis (DMA). Compared with DOP, the ECT plasticized PVC can exhibits better thermal stability, more excellent tensile strength (17.28 MPa) and higher stretchability (629.41%), which is 1161% higher than DOP (1.37 MPa) plasticized PVC film. In addition, the migration resistance and volatility stability of ECT are much better than DOP. Therefore, this fully bio-based plasticizer based on tung oil and cardanol is a promising alternative plasticizer for PVC and may be an excellent phthalate substitute from the perspective of human health and sustainable development.     

Succinate-based plasticizers: Effect of plasticizer structure on the mechanical and thermal performance of poly(vinyl chloride) plastic formulations

A new family of succinate-based plasticizers, consisting of molecules with a linear alkyl chain capped with n-alkyl succinates on both ends, was evaluated as potential bio-based plasticizers for stiff polymers. The influence of the central and side alkyl chain lengths on the mechanical and thermal properties as well as the migration behavior of poly(vinyl chloride) (PVC)/plasticizer blends was evaluated. The central chain length had the greatest influence on plasticizer performance, with shorter chains leading to blends with higher stress at break and surface hardness, whereas long chains produced softer blends. An optimum chain central length of five carbon atoms was observed, with longer chains leading to reduced compatibility and exudation of the plasticizer at higher plasticizer concentrations. The entire family of plasticizers performed comparably or better than the commercial plasticizer di(2-ethylhexyl) phthalate (DEHP) when incorporated into the blend at concentrations of 20–60 parts per hundred resin (phr). Overall, the succinate-based plasticizers/PVC blends all exhibited equal or improved tensile properties (by up to 77%), surface hardness (reduced by up to 43%), glass transition temperature (reduced by up to 11°C), and migration into organic media (reduced by up to 38%) when compared with blends with DEHP at 40 phr.     

Migration resistant polymeric plasticizer for poly(vinyl chloride)

Flexible films of poly(vinyl chloride) (PVC) and linear or branched poly(butylene adipate) (PBA), synthesized from 1,4‐butanediol and adipic acid or dimethyl ester of adipic acid, were aged in an aqueous environment for 10 weeks to study how branching, molar mass, and end‐group functionality affect the leaching of polyester plasticizer from thin films. Principal component analysis was applied to reveal patterns and correlations between mechanical properties, material characteristics, and aging behavior. Introduction of branches in the polyester structure increased the miscibility between PVC and the polyester, resulting in improved mechanical properties and lower water absorption. Methyl ester end‐group in PBA polyester stabilized the polymeric plasticizer toward hydrolysis, and reduced the formation and migration of monomeric degradation products from the blends during aging in water. The combination of branched structure with methyl ester end‐groups resulted in a migration resistant polymeric plasticizer. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 2458–2467, 2007     

Stabilization of epoxidized soybean oil‐plasticized poly(vinyl chloride) blends via thermal curing with genistein

In an effort to alleviate the well‐known toxicity effect of phthalate derivatives on human health, genistein (G) modified epoxidized soybean oil (ESBO) has been investigated as an alternative “green” plasticizer for poly(vinyl chloride) (PVC) with potential application in medical products. As evidenced by a single glass transition that shifts systematically with composition in conjunction with the melting point depression of G crystals, ESBO is not only a good plasticizer to PVC, but also miscible with G. Moreover, ESBO is an excellent compatibilizer to the immiscible PVC/G pair. Furthermore, PVC/ESBO/G ternary blends revealed complete miscibility in the amorphous state. Of particular interest is that ESBO‐plasticized PVC is thermally curable with G at elevated temperatures above 220 °C and affords relatively stable G modified ESBO‐plasticized PVC for blood contact medical applications such as blood bags and hemodialysis tubings. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46472.