Poly(?-caprolactone)-based ‘green’ plasticizers for poly(vinyl choride)

A series of proposed plasticizers for poly(vinyl chloride) (PVC), based on poly(?-caprolactone) (PCL) with octanoate and benzoate-terminal groups, were synthesized with various microstructures and molecular weights (MW) and tested for biodegradability as well as for mechanical performance, and leaching resistance in blends with PVC. The plasticization efficiency of each was characterized by measuring the glass transition temperature (T_g) and tensile properties of PCL/PVC blends. The PCL-octanoate plasticizers demonstrated plasticization efficiency similar to di(ethylhexyl) phthalate (DEHP) with the same plasticizer loading. PCL-benzoate/PVC blends had much higher T_gs (∼20 °C higher) compared to PCL-octanoate/PVC and DEHP/PVC blends. Yield stresses were about two times higher for PCL-benzoate/PVC blends compared to PCL-octanoate/PVC and DEHP/PVC blends, reflecting the stiffer nature of such blends. Biodegradation was rapid for all PCL-octanoates, with the exception of linear PCL-octanoates with arm molecular weights >10³ g mol⁻¹. Biodegradation rates of PCLs by Rhodococcus rhodocrous were not affected by microstructure for the range of PCL topologies studied (linear versus three or four arms) but were slower for PCLs made from commercial PCL-diols that had a central ether linkage due to the initiator used to make these compounds. Leaching resistance was higher as PCL molecular weight increased and, for pairs of comparable sized species, significantly less PCL-benzoate leached out compared to the PCL-octanoate. For the range of PCL topologies studied, the number of arms did not significantly affect leaching resistance. In summary, both the end group and the molecular weight influenced the leaching resistance of the PCL. PCL-octanoates were comparable plasticizers to DEHP in terms of the mechanical properties examined, and were rapidly degraded by a common soil microorganism.     

Designing anti-migration furan-based plasticizers and their plasticization properties in poly (vinyl chloride) blends

The use of bio-based plasticizers with low toxicity and good compatibility with polyvinyl chloride (PVC) has attracted more attention in the recent years. With bio-based 2, 5-furandicarboxylic acid (FDCA) and butyl oligo-glycol ethers as raw materials, three liquid furan-based plasticizers of di(butyl glycol) furan-2,5-dicarboxylate, di(butyldiglycol) furan-2,5-dicarboxylate and di(butyltriglycol) furan-2,5-dicarboxylate were synthesized by direct esterification. The chemical structure of three plasticizers was characterized with FTIR, ¹H NMR and ¹³C NMR. From DMA measurement, the glass transition temperature (T_g) of the plasticized PVC was decreased gradually when furan-based plasticizers were added to PVC formulation from 30 up to 50 phr. Due to lots of ether bonds in furan-based plasticizers, they expressed over two-fold lower migration in organic solvent compared with the traditional plasticizer diethylhexyl phthalate (DEHP). Through the characterization of elongation at break, hardness and thermal stability, furan-based plasticizers presented the same plasticization properties as DEHP, and had potential industrial application prospects.     

Application of ionic liquids as low-volatility plasticizers for PMMA

Room temperature ionic liquids (ILs) based on imidazolium salts, were found to be excellent plasticizers for poly(methyl methacrylate), with improved thermal stability, and the ability to reduce glass transition temperatures to near 0 °C. Because ILs have environmentally benign properties, they can be used in place of traditional chemicals in numerous products and processes. In this work, PMMA was formulated using dioctyl phthalate, DOP, as a traditional plasticizer, and properties were compared to PMMA plasticized with two ILs: butyl methylimidazolium/hexafluorophosphate, [bmim⁺][PF₆⁻], and hexyl methylimidazolium/hexafluorophosphate, [hmim⁺][PF₆⁻]. Formulations incorporated up to 30 vol.% DOP and 50 vol.% ILs. Bulk and plasticized polymers were characterized for glass transition temperature, elastic modulus, and the thermal stability of the plasticizers.     

Gelation/fusion behavior of PVC plastisol with a cyclodextrin derivative and an anti-migration plasticizer in flexible PVC

We successfully evaluated the effects of 2,3,6-per-O-benzoyl-β-cyclodextrin (Bz-β-CD) on the rheological properties of PVC plastisols and the migration behavior of plasticizer from flexible PVC. Two types of plasticizer, di-isononyl phthalate (DINP) and diisononyl cyclohex-4-ene-1,2-dicarboxylate (Neocizer), along with Bz-β-CD as a migration inhibitor were mechanically mixed into an emulsion grade PVC resin to prepare plastisols. The presence of Bz-β-CD was expected to facilitate formation of stable complexes with DINP or Neocizer in the flexible PVC. It was necessary to determine whether changes in the processing conditions of the PVC plastisol were needed for use in this application. To this end, the viscoelastic properties of the plastisols, including the elastic modulus, G′, and the viscous modulus, G″, were continuously monitored as a function of temperature during the gelation and fusion processes using rheological analysis techniques. The results showed that complete gelation was slightly delayed and both moduli (G′ and G″) decreased upon addition of Bz-β-CD to the PVC matrix. FE-SEM images yielded insight into the gelation and fusion processes. The curing conditions and physical properties of the flexible PVCs containing Bz-β-CD were optimized, and the influence of Bz-β-CD on the migration of the plasticizers and the stability of the flexible PVC was studied. The results showed that Bz-β-CD reduced migration of DINP and Neocizer from the flexible PVC by almost 40% and 25%, respectively, thereby favorably restricting migration within the flexible PVC.     

GC-MS/MS用于微波条件下PVC塑料中增塑剂向橄榄油迁移行为的研究

采用GC-MS/MS法研究了微波条件下PVC塑料中3种增塑剂(邻苯二甲酸二异丁酯(DIBP)、邻苯二甲酸二(2-乙基)己酯(DEHP)和己二酸二(2-乙基)己酯(DEHA))在橄榄油中的迁移规律,考察了微波加热时间和微波功率对增塑剂迁移的影响,并与常规加热条件下的迁移进行比较。结果表明,3种增塑剂在橄榄油中的迁移量随微波功率和加热时间的增加而增大,且微波加热条件下的迁移量显著高于常规加热方式。     

Encapsulation of β-cyclodextrin by in situ polymerization with vinyl chloride leading to suppressing the migration of endocrine disrupting phthalate plasticizer

We performed the encapsulation of β-cyclodextrin (β-CD) in PVC by in situ polymerization with vinyl chloride monomer (VCM), and investigated the effect of CD encapsulation on the suppression of dioctyl phthalate (DOP) migration suspected as endocrine disruptor. β-CD was partially modified with 3-(methacryloxy)propyl trimethoxysilane and modified β-CD (MCD) was then encapsulated in PVC through suspension polymerization via radical reaction between double bonds MCD and VCM. Resulting MCD-encapsulated PVC (MCD_x-PVC) exhibited the similar morphology and characteristics to commercial PVC. For MCD_x-PVCs plasticized with DOP, they showed the considerably suppressed DOP migration as well as the similar optical and mechanical properties to conventionally plasticized PVC. In particular, the plasticized MCD_x-PVCs exhibited the superior suppression of DOP migration compared to the plasticized PVC where MCD and DOP were introduced by conventional melt mixing. Therefore, the encapsulation of MCD in PVC is thought to be an effective approach to producing the ecological PVC material.     

Non-phthalate plasticizer from camphor for flexible PVC with a wide range of available temperature

A bio-based plasticizer, (1′,7′,7′-trimethyldispiro [ [1,3]dioxolane-2,2′-bicyclo [2.2.1]heptane-3′,2″- [1,3]dioxolane]-4,4″-diyl)bis (methylene) dioctanoate (abbreviated as CDO), was designed to replace a traditional phthalate-based plasticizer. The structure of CDO was analyzed by ¹H NMR. The characteristics of CDO plasticizers, which were judged to have excellent compatibility with PVC due to their solubility parameters, were evaluated by thermal and mechanical analyses and compared with dioctylphthalate (DOP). PVC with 20% CDO added was thermally stable up to 251.9 °C and exhibited excellent strength and flexibility with a high T_g derived from its robust and bulky structure. In addition, since CDO is intertwined with the polymer chain, it shows excellent migration properties in many solvents. The results of our study suggest that CDO can be applied to produce flexible PVC and to expand PVC coverage due to the improved migration resistance.     

Branched plasticizers derived from eugenol via green polymerization for low/non-migration and externally/internally plasticized polyvinyl chloride materials

The synthesis of nontoxic plasticizers derived from the waste residues of the rosin-processing industry can reduce pollution and promote the high-value utilization of the waste residues of rosin. In this study, four kinds of sustainable branched plasticizers derived from a biomass resource, eugenol (derived from the waste residues of the rosin processing industry), were synthesized via one-pot solvent free polymerization and used to plasticize polyvinyl chloride (PVC). Internally plasticized PVC was fabricated using thiolated DPE (branched plasticizers based on eugenol). The thermal stability, tensile properties, microstructure, volatility behavior, and solvent extraction resistance of plasticized PVC were investigated. Compared with the behavior of the commercial plasticizer dioctyl phthalate, the thermal stability, plasticizing efficiency, and migration resistance of the branched plasticizers are superior. The acute oral toxicity dose of each branched plasticizer was extremely high at 5000 mg/kg of body weight, with no deaths among test animals. Compared with externally plasticized PVC, the internally plasticized PVC showed zero weight loss in volatility and leaching tests despite its less effective plasticization. All the branched plasticizers have potential application in plastic products.     

Synthesis of a bio-based plasticizer from oleic acid and its evaluation in PVC formulations

The bio-based plasticizers have been extensively developed due to their high compatibility and low toxicity. In this study, the bio-based plasticizers of methyl 10-(2-methoxy-2-oxoethansulfonyl) octadecanoate (MDA) and ethyl 10-(2-ethoxy-2-oxoethanesulfonyl) octadecanoate (EDA) were synthesized from the oleic acid and thioglycolic acid and characterized by ¹HNMR and FT-IR. The prepared materials were applied as plasticizers in Poly(vinyl chloride) (PVC) and their properties were compared with the commercial plasticizer, Bis(2-ethylhexyl) phthalate (DOP). The viscosities of prepared plastisols from novel designed plasticizers were lower than DOP. The results of mechanical properties showed that the synthesized plasticizers of MDA and EDA have the ability of plasticizing effects similar to DOP on PVC. Thermogravimetric analysis (TGA) indicated that both MDA and EDA have higher thermal stability than DOP. Two polar ester as well as polar sulfone groups in the chemical structure of MDA and EDA led to lower migration, volatility and exudation than DOP.     

Sol-Gel Transition and Equilibrium Shear Modulus of Poly(vinyl chloride) and Plasticizers

The elasticity of poly(vinyl chloride) gels with molecular weight distribution (M_w/M_n), of 2.16 have been studied in the region beyond their gel points. Dynamic storage modulus G′, and equilibrium gel shear modulus of elasticity G_e, at low frequencies (ω) have specific developments as a function of polymer concentrations c, and plasticizers. The scaling elasticity from G_e = kε^z equation holds at different PVC plasticizer gels. The scaling exponent z, and constant k. ε is defined as the relative distance, ε = (|c − c_g|)/c_g, the calculated z = 2.45 ± 0.15. Furthermore, this analysis provides constant k with certain informations about the dependency of gel elasticity on the kind of plasticizer. Near the sol-gel transition temperature T, G_e decreases rapidly with increasing temperature. The normalized moduli G_eM/cRT, of the gels at different temperature, and/or c were dependent on the relative distance from the gelation point ε, and PVC and plasticizers concentration respectively. These results suggested mesh size of gel network near the gelation point for PVC with bis(2-ethylhexyl) phthalate (DOP) or di-n-butyl sebacate (DBS) plasticizers that has been newly reported.     

GC-MS Assisted with Chemometric Methods Applied for Investigation of Migration Behavior of Phthalate Plasticizers in Fatty Foods Simulant

PVC films with different thickness and different contents of 9 phthalate plasticizers (PAEs) were manufactured according to a uniform design method. The migration contents of PAEs in isooctane, which was set as a fatty foods simulant, were first determined using GC-MS analysis. It was found that the chromatographic peaks of diisononyl ortho-phthalate (DINP) and diisodecyl ortho-phthalate (DIDP) very considerably overlapped, with a lower signal to noise ratio (SNR). For resolution of the noisy overlapped peaks, twice continuous wavelet transform (CWT) was adopted. Then, the migration models of PAEs were obtained by the non-negative least squares method (NNLS). The results show that the noisy overlapped peaks were successfully resolved with increasing the SNR 10 times; the migration ratio of the 9 PAEs at 70 °C are located with the range 0.0556–0.3383 %; the migration amount of a specific plasticizer is proportional to its content and some coexisting plasticizers; temperature is a significant impact factor for the migration process. The proposed chemometric-assisted GC-MS analysis provides a new approach for investigation of this complex process.     

New development on plasticized poly(lactide): Chemical grafting of citrate on PLA by reactive extrusion

New plasticization ways based on low molecular plasticizers from citrates family were investigated to improve the ductility of poly(lactide) (PLA). Grafting reactions between anhydride-grafted PLA (MAG-PLA) copolymer with hydroxyl-functionalized citrate plasticizer, i.e. tributyl citrate (TbC), were so-carried out through reactive extrusion. TributylO-acetylcitrate (ATbC) was used as a non-functionalized reference. Both plasticizers drastically decreased the T_g of PLA. However, the grafting reaction of TbC into MAG-PLA revealed a shift of PLA T_g toward higher values. After 6 months of aging, no phase separation was observed. However, plasticizer leaching was noticed in the case of PLA/ATbC materials, leading to the shift of T_g toward lower temperatures. In contrast, no major leaching phenomenon was noticed in PLA/TbC and PLA/MAG-PLA/TbC blends, indicating that the mobility restriction derived from the hydrogen bonding that can occur between PLA and TbC as well as the grafting reaction of TbC into MAG-PLA enabled to reduce leaching phenomena.     

Internal plasticization of poly(vinyl) chloride using glutamic acid as a branched linker to incorporate four plasticizers per anchor point

Internal plasticization of polyvinyl chloride (PVC) using thermal azide‐alkyne Huisgen dipolar cycloaddition between azidized PVC and electron‐poor acetylenediamides incorporating a branched glutamic acid linker resulted in incorporation of four plasticizing moieties per attachment point on the polymer chain. A systematic study incorporating either alkyl or polyethylene glycol esters provided materials with varying degrees of plasticization, with depressed T_g values ranging from ?1 °C to 62 °C. Three interesting trends were observed. First, T_g values of PVC bearing various internal plasticizers were shown to decrease with increasing chain length of the plasticizing ester. Second, branched internal plasticizers bearing triethylene glycol chains had lower T_g values compared to those with similar length long‐chain alkyl groups. Finally, thermogravimetric analysis of these internally plasticized PVC samples revealed that these branched internal plasticizers bearing alkyl chains are more thermally stable than similarity branched plasticizers bearing triethylene glycol units. These internal tetra‐plasticizers were synthesized and attached to PVC‐azide in three simple synthetic steps. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019 , 57, 1821–1835     

Application of a bio‐based polyester plasticizer modified by hydrosilicon‐hydrogenation reaction in soft PVC films

A kind of bio‐based plasticizer, poly (hexanediol maleic) (MH), was synthesized using 1,6‐hexalene and maleic acid as raw materials, and it was modified by hydrosilicon‐hydrogenation reaction to improve its plasticizing efficiency. The chemical structure and plasticizing performance of MH and its modification product (MHA) were characterized by Fourier‐transform infrared spectroscopy (FTIR), proton nuclear magnetic resonance (¹H‐NMR), X‐ray photoelectron spectroscopy (XPS), and Dynamic mechanical analysis (DMA). It was found that the hydrosilicon‐hydrogenation modification effectively improved the plasticizing efficiency of MH, reflecting on the decreased T_g and the increased elongation at break of PVC blends. The migration resistance of PVC blends was tested and analyzed by solubility parameters, which revealed that the migration stabilities of PVC blends were promoted after modification. It was verified that the hydrogen bonding interaction between the C?O group of plasticizers and α‐hydrogen of PVC exhibited in FTIR analysis was the main reason for the improvement of plasticizer performance of MH. Moreover, a new hydrogen bonding formed between Si? O? Si of MHA and the α‐hydrogen of PVC derived from XPS also caused the further improvement of plasticity for MHA.     

Performance testing of a green plasticizer based on lactic acid for PVC

In order to develop alternative green plasticizers, a bio-based plasticizer, acetylated lactic acid 1,4-cyclohexanedimethyl ester(ALCH), with novel molecule geometry was synthesized from l-lactic acid and characterized by FTIR, ¹H NMR and matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF-MS). The prepared ALCH was mixed with poly(vinyl chloride) (PVC) as plasticizer and the results indicated that the PVC films plasticized by ALCH have better migration and volatility stability than acetyl tributyl citrate (ATBC). In addition, ALCH could endow PVC products with excellent performance of strength, elongation and elasticity. With the substitution of ALCH for ATBC, glass transition temperature (Tg) of PVC films decreased gradually from 61.3°C to 55.0 °C. The self-polymerization of lactic acid gives ALCH better plasticizing effectiveness than ATBC.     

Nonmigratory internal plasticization of poly(vinyl chloride) via pendant triazoles bearing alkyl or polyether esters

Branched and linear nonmigratory internal plasticizers attached to PVC by a pendant triazole linkage were synthesized and investigated. Copper-free azide-alkyne thermal cycloaddition was employed to covalently bind triazole-based phthalate mimics to PVC. To systematically investigate the effect of plasticizer structure on glass transition temperature, several architectural motifs were explored. Free volume theory was considered when designing many of these internal plasticizers: hexyl-tethers were utilized to generate additional space between the triazole-phthalate mimic and the polymer backbone. Miscibility of these triazole-plasticizers in PVC is important: variation of the ester moieties on the triazole possessing alkyl and/or poly(ethylene oxide) chains produced a wide range of glass transition temperatures (T_g): from anti-plasticizing 96 °C, to highly efficient plasticized materials exhibiting T_g values as low as −42 °C. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018 , 56, 2397–2411     

The migration of plasticizers into petroleum oils

The importance of the migration of plasticizers, and the basic differences due to types of contact, are analysed. The migration of phthalate plasticizers from plasticized PVC to several petroleum oils was studied quantitatively by a method based on labelled plasticizers and measurements of the radioactivity of the medium. The results are compared with those obtained by methods of radioactivity and weight loss; differences are discussed. In most cases, the migration of plasticizer is accompanied by diffusion of oil into the polymer. The effects of the following factors on the migration process were examined: (a) the nature of petroleum oil; (b) the nature of the phthalate plasticizer; (c) the amount of plasticizer; (d) the plasticization process; (e) the temperature; and (f) the time.     

Performance evaluation of new plasticizers for stretch PVC films

Six stretch PVC films have been formulated to have Shore A hardness of approx. 80 and nominal thickness of 15 μm with the aim of evaluating the performance of plasticizers from renewable and non-renewable sources for stretch PVC films intended to be employed as packaging. The reference film was produced with DEHA and ESBO, while the other films were produced with conventional plasticizers (ATBC and Polyadipate), new plasticizers from renewable sources (Mixture of glycerin acetates and Acetic acid esters of mono- and diglycerides of fatty acids) or a plasticizer employed in toy and childcare applications (DEHT) as a third plasticizer. The films were evaluated as to their physical and mechanical properties (durometer hardness, tensile strength and elongation), IR spectroscopy and light transmission. The several plasticizers influenced the mechanical properties of the PVC films to different degrees. All films will probably show adequate performance when used in packaging applications. Nevertheless, the vegetable oil-based plasticizers showed better mechanical performance than the other plasticizers when compared to DEHA.     

Free radical polymerization of glycidyl methacrylate in plasticized Poly(vinyl chloride)

Kinetic of free radical in-situ polymerization of glycidyl methacrylate (GMA), was studied in a complex evolutionary system: poly(vinyl chloride) (PVC) plastisols. A predictive model of conversion-time profile based on free radical mechanism was proposed and structure of the modified PVC system developed was investigated by NMR analyses. In order to elucidate the mechanism of the reaction, model molecules for PVC were used with NMR and MALDI-TOF characterization. It was found that in-situ polymerization of GMA in PVC plastisols leads to both homopolymerization and grafting of GMA onto PVC backbone by hydrogen abstraction. For 33 wt% GMA loaded, grafting efficiency is 67% with an amount of grafted poly-glycidyl methacrylate (pGMA) equals to 22 wt%. Thus, this article discloses a new type of PVC plastisols called reactive plastisols where, in addition to usual plasticizers, PVC is modified by polymerizable GMA monomer.     

Ionic Liquid‐Based,Liquid‐Junction‐Free Reference Electrode

In this paper, we describe a new type of polymer membrane‐based reference electrode (RE) based on ionic liquids (ILs), in both liquid‐contact (LCRE) and solid‐contact reference electrode (SCRE) forms. The ILs used were bis(trifluoromethane sulfonyl)amid with 1‐alkyl‐3‐methyl‐imidazolium as well as phosphonium and ammonium cations. In addition to their charge stabilisation role, it was found that the ILs also functioned as effective plasticizers in the PVC matrix. The LCREs and SCREs were prepared using the same design as their corresponding indicator electrodes. LCREs were prepared by casting in glass rings while SCREs were prepared on platforms made using screen‐printing technology, with poly(3‐octylthiophene‐2,5 diyl) (POT) as the intermediate polymer. After potentiometric characterization of the response mechanism, the practical performance of the REs was studied using potentiometric titrations (Pb²⁺ and pH), and characterised using cyclic voltammetry and impedance spectroscopy. All results were compared via parallel experiments in which the novel RE was substituted by a conventional double junction Ag/AgCl reference electrode. The mechanism of response is most likely based on a limited degree of partitioning of IL ions into the sample thereby defining aquo‐membrane interfacial potential. Despite their simple nature and construction, the REs showed excellent signal stability, and performed well in the analytical experiments. The identical mode of fabrication to that of the equivalent indicator (or Ion‐Selective Electrode, ISE) will facilitate mass‐production of both indicator and reference electrode using the same fabrication line, the only difference being the final capping membrane composition.