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     

食品级增塑剂乙酰化单甘油脂肪酸酯(ACETEM)的应用研究

以纯天然植物油甘油和椰子油等原料合成具有不同碳链长度的植物油基环保型增塑剂乙酰化单甘油脂肪酸酯(ACETEM)。通过红外光谱(FT-IR)、气质联用(GC-MS)表征手段测定其结构,并利用热重分析仪(TGA)测定其本身及PVC试片的热稳定性能,对其PVC试片的迁移率和挥发损失率研究,探索了其与PVC的相容性能,结果表明,ACETEM具有较好的热稳定性能,并且与PVC具有较好的相容性,将其应用在食品包装材料上具有很好的前景。     

PVC膜改性研究进展

综述了近年来PVC膜改性的技术进展,对PVC膜进行物理和化学改性,可以改变它的表面性质、阻止增塑剂向表面迁移并赋予PVC膜生物相容性等。改性后的PVC膜,不仅能应用于传统领域。还能应用于一些新的领域。     

Improving the migration resistance against phthalate plasticizer in polyvinyl chloride/graphene oxide composites

Phthalic plasticizer plays an important role in processing and manufacturing one of the universal polymer materials, poly (vinyl chloride) (PVC), which has been widely applied in every aspect of our lives. However, there still exists the intrinsic problem in migration resistance of phthalic plasticizer in long-term use. In this work, we take a facile and convenient approach by incorporating commercial graphene oxide (GO) into PVC matrix to prepare polyvinyl chloride/graphene oxide (PVC/GO) composites, forming a sheet structure for improving the migration resistance of phthalic plasticizer. The advantages of GO that has abundant oxygen-containing groups on its surface, including carboxyl groups at the sheet edges, epoxy groups, and hydroxyl groups on its basal planes. Especially, these oxygen-containing groups in GO are beneficial to blend with long molecular chain of PVC and the sheet structure of GO can prevent phthalic plasticizer migrating from interior PVC. Addition of GO not only effectively enhanced the mechanical properties of PVC/GO composites but also improve their migration resistance due to the sheet structure. This strategy provides an attractive way to solve the problem of migration of plasticizer with simple incorporation GO into the matrix of PVC, reinforcing the composite properties and broadening its applied fields.     

Migration of Epoxidized Sunflower Oil and Dioctyl Phthalate from Rigid and Plasticized Poly(vinyl chloride)

The aim of this paper is the determination of the specific migration of epoxidized sunflower oil (ESO) from rigid and plasticized poly(vinyl chloride) (PVC) into food simulants. ESO was obtained by epoxidation of commercial sunflower oil and used as a thermal organic co-stabilizer for PVC. For that purpose, rigid and plasticized (0, 15, 30, and 45 wt% of dioctyl phthalate or DOP) PVC films stabilized with ESO in the presence of Zn and Ca stearates were used to perform migration testing in olive oil. The test conditions were 12 d at 20 and 40°C and 2 h at 70°C with and without agitation.

The determination of ESO migration was carried out by gas chromatography-mass spectrometry (GC-MS). ESO was quantified by an external standard addition method, using linoleic acid (C_18:2) as the external standard. The influence of various parameters, such as the agitation and time of contact, the temperature, the presence or the absence of the plasticizer, and the plasticizer concentration, was considered.     

Synthesis of a bio-based plasticizer from vanillic acid and its effects on poly(vinyl chloride)

A new bio-based plasticizer, VA8-8, was prepared derived from vanillic acid, and its structure was verified by nuclear magnetic resonance. It was incorporated into poly(vinyl chloride) (PVC) to replace dioctyl phthalate (DOP), and its plasticizing performance was evaluated. The results indicated that VA8-8 shows good compatible with PVC resin, and has a excellent plasticizing effect for PVC. When DOP was partially or completely substituted with VA8-8, the T_g value PVC blends dropped from 34.6 to 24.3°C and the elongation at break increased from 196.4% to 301.9%, suggesting the enhanced plasticizing efficiency of plasticizer. The plasticizing mechanism was also simulated, and the interactions between VA8-8 and PVC molecules were discussed. The thermogravimetric analysis showed VA8-8 can more effectively improve the thermal stability of PVC than DOP. In addition, the migration resistance of VA8-8 was generally superior to that of DOP. Therefore, VA8-8 is a comparable to or better plasticizer than DOP, and it is a promising alternative plasticizer for PVC.     

Surface treatment of plasticized poly(vinyl chloride) to prevent plasticizer migration

In this investigation, plasticized poly(vinyl chloride) (PVC) was treated with poly(azido acrylate)s to prevent plasticizer migration. This was achieved by modification of PVC sheets with poly(azido acrylate)s in a dichloromethane solution followed by irradiation under UV light. The surface‐modified PVC sheets with poly (azido acrylate)s were characterized with Fourier transform infrared spectroscopy and scanning electron microscopy analyses. The migration of the plasticizer was prevented to a large extent from modified PVC in comparison with unmodified PVC. The amount of plasticizer migration with respect to the irradiation time, incubation time, and number of dipping times was evaluated. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

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     

一种新型蓖麻油酸季戊四醇酯的制备及应用

用季戊四醇和蓖麻油酸通过酯化反应反应制备了蓖麻油季戊四醇酯。采用红外光谱仪和核磁共振仪对制备的产品的化学结构进行表征。并将其作为增塑剂与聚氯乙烯（PVC）共混,研究了塑化PVC的平衡扭矩、热性能和力学性能,对该增塑剂在不同溶媒中的耐迁移性进行了研究,并与邻苯二甲酸二辛酯和环氧大豆油的塑化性能进行了对比。结果表明,蓖麻油季戊四醇酯塑化PVC的加工平衡扭矩为14.9 N·m,改善了PVC的加工稳定性;塑化PVC的拉伸强度为23.28 MPa,断裂伸长率为263.13 %,耐迁移性能较邻苯二甲酸酯和环氧豆油较好,可以作为PVC增塑剂使用。     

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.     

Effects of epoxidized sunflower oil on the mechanical and dynamical analysis of the plasticized poly(vinyl chloride)

Epoxidized soybean oil (ESBO), is one of the most commonly used epoxides because of its typical combined roles as a plasticizer and heat stabilizer. In this study, a novel plasticizer of poly(vinyl chloride) (PVC) resins, epoxidized sunflower oil (ESO), was synthesized, and its performance was evaluated. ESO was designed to act as a coplasticizer and a heat stabilizer like ESBO. ESO is used as organic coplasticizer for plasticized PVC containing Ca and Zn stearates as primary stabilizers and stearic acid as lubricant. Di‐(2‐ethylhexyl) phthalate (DEHP), a conventional plasticizer for PVC, was partially replaced by ESO. Mechanical properties (tensile and shore D hardness) were investigated. The performance of ESO to ESB0 (20 g) for comparison, indicated that ESO could be used as secondary plasticizer for PVC in combination with DEHP. All mechanical and dynamical properties of plasticized PVC sheets varied with the oxirane oxygen of the ESO. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Photocross-linking of dithiocarbamate-substituted PVC reduces plasticizer migration

Medical grade poly(vinyl chloride) (PVC) sheets and tubes were surface modified by nucleophilic substitution of chlorine atoms of PVC by photoactive N,N-diethyl dithiocarbamate (DTC) in aqueous media in the presence of a suitable phase transfer catalyst (PTC) at 55°C. The modified surface was cross-linked by irradiation with u.v. light in an attempt to create a barrier for the diffusion of the plasticizer di-(2-ethylhexyl phthalate) (DEHP). Of the various PTCs examined for the reaction, tetrabutyl ammonium salts were found to be very effective, whereas crown ethers such as 18-crown-6 was least effective. The effect of concentration of PTC and DTC, time of reaction and irradiation dose on the extent of plasticizer migration was examined in petroleum ether for various periods of time at 30°C. The migration of DEHP from PVC modified under optimum conditions was less than 5% in 120 h, whereas the unmodified PVC lost virtually all its plasticizer ( > 30%) during the same period. Determination of the stress-strain properties of modified PVC sheets showed a reduction of approximately 30%. However, the values were still within the range prescribed for vinyl chloride plastics used for medical applications.     

Development of new PVC materials. Characterization and feasibility of diamond coatings on model PVC materials

Diamond-like, tetrahedrally bonded amorphous carbon (ta-C) coating was used to enhance the wear resistance of laboratory-made microstructured poly(vinyl chloride) (PVC) surfaces. Formulation of PVC samples was kept simple; they contained only stabilizer and plasticizer added to PVC. Two sizes of microstructures were imprinted on PVC. Both smooth and microstructured PVC surfaces were coated with amorphous diamond and the surfaces were characterized by spectroscopic ellipsometry, AFM and contact profilometry. In addition, water contact angles were measured. The plasticizer, plasticizer concentration and amorphous carbon coating affected the topography of the microstructure and the water contact angles on surfaces. The ta-C-coated microstructured surfaces were worn with a soiling and wearing drum tester to study their wearing behavior. Surface topographies were measured with a profilometer after wearing studies.     

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.     

Effect of thermal annealing on plasticizer migration in poly(vinyl chloride)/dioctyl phthalate system

Plasticizer migration studies dealing with poly(vinyl chloride) (PVC) sheets and liquid surrounding media revealed two parallel phenomena, migration of plasticizer and liquid penetration, that take place simultaneously. The present work was focused on correlating the structural differences of the PVC material with the aforementioned processes. The plasticizer and the liquid medium used were dioctyl phthalate and isopropanol, respectively. Emphasis was placed on any rearrangement of the polymer morphology occurring when elevated test temperatures were employed for a relatively long period of time (crystallization). The result was that the PVC structure seemed to become more compact, forcing the liquid medium that had already penetrated to come out. Furthermore, these experiments showed that plasticizer migration and liquid penetration were related to the polymer structure. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 79: 1780–1786, 2001     

Evaluation effects of biobased plasticizer on the thermal,mechanical, dynamical mechanical properties,and permanence of plasticized PVC

Sunflower oil (SO) is a renewable resource that can be epoxidized, and the epoxidized SO has potential uses as an environmentally friendly in polymeric formulations, especially for poly (vinyl chloride) (PVC). Epoxidized sunflower oil (ESO) was prepared by treating the oil with peracetic acid generated in situ by reacting glacial acetic acid with hydrogen peroxide. Epoxidation was confirmed using spectroscopic and titration methods. ESO was used as a coplasticizer in PVC for the partial replacement of di‐(2‐ethyl hexyl) phthalate (DEHP). The effect of ESO on the thermal stability of plasticized PVC was evaluated by using synmero scale for the sheets. In presence of ESO plasticized PVC samples showed a reduction in discoloration and the number of conjugated double bonds. By using thermogravimetry, the incorporation of 15/45 of ESO/DEHP in PVC presents the lowest weight loss. The results of the shore hardness and mechanical properties showed that a proportion of DEHP could be substituted by ESO. By use of DMA, the formulation which contains 25 % wt of ESO in plasticizer system shifts the glass transition temperature (T_g) to ambient temperature. The migration phenomenon was studied on PVC based samples plasticized with DEHP and ESO in varying amounts. The migration was monitored by the weight loss percentage of the samples immersed into n‐hexane or heated in an oven. The amount of extracted or volatilized DEHP is proportional to the added ratio of ESO in plasticizer system. All of this favored the partial replacement of DEHP by ESO as biobased plasticizer for flexible PVC. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

高分子量增塑剂PPA抑制软质PVC中DOP迁移的研究

将高分子量增塑剂聚己二酸丙二醇(酯PPA)与邻苯二甲酸二辛(酯DOP)共混以抑制软质聚氯乙(烯PVC)中DOP的迁移,探讨了PPA和DOP用量对DOP的溶剂抽出率和挥发损失率以及软质PVC制品力学性能的影响。结果表明:PPA能有效抑制软质PVC样品中DOP的溶剂抽出率和挥发损失率,PPA含量越高,抑制效果越明显;当PPA/DOP=10/30时软,质PVC样品的力学性能得到了较好的保持。     

Stress cracking of rigid polyvinyl chloride by plasticizer migration

Environmental stress cracking (ESC) (failure caused by crack and craze formation at a stress less than the yield stress) reduces the service life of many plastic products. This paper is concerned with ESC of rigid PVC products which are in contact with a plasticized PVC material. The ESC affect (as measured by elongation to break) is reduced at faster strain rates and by higher plasticizer viscosity, which suggests a mechanism requiring flow of plasticizer into a growing craze. Well fused (gelled) PVC made at a higher melt temperature slowed but did not eliminate environmental stress cracking. Rubber impact modifier added to the rigid PVC had no effect on ESC. Environmental stress cracking can be avoided by using flexible PVC that has a non-migrating plasticizer or by designing the product so that rigid PVC is not stressed while in contact with plasticized PVC.     

Study of transfer process of liquid into and plasticizer out of plasticized PVC by using short tests

When plasticized PVC packagings are put into contact with liquids (blood, food), a migration of plasticizer and additives may occur, being responsible for a contamination of the liquid and a decrease in the mechanical properties of polymer. The interest in short tests is especially pointed out. In contrast to classical real tests, they are not highly time consuming. Moreover, the study of kinetics transfer is easy to complete, because of the constant concentration of liquids in PVC during a short time. A modeling of the transfer process is shown, followed by calculation of the transfer for long real experiments. The model described takes into account both simultaneous transfers, the one concerned with the plasticizer from PVC into liquid and the other with the liquid into the PVC. The study conducted with n-heptane as the liquid allows one to understand this complicated transfer problem.     

Prior sample history vs. plasticizer migration phenomena in flexible poly(vinyl chloride) sheets

Compression-molded sheets of plasticized poly(vinyl chloride) (PVC) were prepared to investigate plasticizer migration phenomena into paraffin oil environment. Interest is focused on prior sample history: Specimens from sheets of different dioctyl phthalate (DOP) contents are maintained in the liquid medium until the plasticizer concentration drops to a predetermined value. Then they are switched into “fresh” paraffin oil, at the same immersion temperature, to compare long-term migration behavior with that of new sheets of this predetermined plasticizer content, i.e., excluding the prior desorption cycle. The results obtained reveal restriction of the migration activity for the two-stages specimens.