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.     

抑制PVC制品中小分子增塑剂迁移的研究

采用气-固相氯化法和氯化原位接枝法对小分子增塑剂邻苯二甲酸二辛酯(DOP)进行了改性,得到的产物分别与PVC共混,并对其失重率、沸点、力学性能进行了研究。结果表明:氯含量为30%左右的氯化DOP,从PVC制品表面迁移出来的几率最小;DOP氯化原位接枝丙烯酸丁酯(BA)后作为PVC的增塑剂,当BA含量在1～10份时材料的失重较少,而BA含量在10份时材料的强度及韧性最好。     

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     

Flexible poly(vinyl chloride) sheets: 1. Interrelations between ultra-violet irradiation and plasticizer migration into alcohols

Ultra-violet (u.v.) irradiation of poly(vinyl chloride) (PVC) sheets is a well known technique for inducing surface crosslinking in order to prevent plasticizer migration phenomena. Accordingly, for varying u.v. irradiation doses, long-term migration data obtained by radioactivity measurements are presented for the systems PVC/labelled dioctyl phthalate (DOP)/methanol, ethanol, n-propanol and n-butanol. Even at the higher doses examined, migration was found to be only moderately hindered; primary kinetics studies also yielded similar results to those already established for untreated material. This behaviour was attributed mainly to counderdiffusion processes resulting in progressive failure of the protective surface layer developed during irradiation.     

A novel route for preparation of PVC sheets with high UV irradiation resistance

A novel acrylonitrile acrylate copolymer coating was proposed to improve the UV irradiation resistance of poly(vinyl chloride) (PVC) sheets. Its effect on the photoageing properties of the sheets was evaluated by means of Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), yellowness index test, and the oxygen permeability coefficient and mechanical properties measurement. The experimental results show that the novel acrylonitrile acrylate copolymer coating significantly improves the UV irradiation resistance of PVC sheets. Compared with the PVC sheets without coating, the coated PVC sheets show better mechanical properties, lower yellowness index, and smaller oxygen permeability coefficient after UV irradiation. The analysis on the SEM images of the PVC sheets indicates that the coating acts as a film to prevent the PVC sheets from UV energy and oxygen that can accelerate the photochemical reactions of PVC. The FTIR analysis confirms that the coating can slow down the microstructures development of the PVC sheets, also indicating that the coating impeded the photochemical reactions of PVC. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

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.     

Application of Poly(butylenes 2-methylsuccinate) as Migration Resistant Plasticizer for Poly(vinyl chloride)

The bio-based and biodegradable polyester poly(butylenes 2-methylsuccinate) (PBM) was successfully used as a polymeric plasticizer to modify poly(vinyl chloride) (PVC) in this work. The tensile properties, plasticization efficiency estimated by the lowered glass transition temperature and the enhanced elongation at break of the PVC/PBM blends and the migration stability of the PBM were investigated. It was indicated that the migration-resistant property of PVC plasticized with PBM was greatly superior to that with dioctyl phthalate (DOP). Furthermore, the tensile properties were comparable to that of PVC/DOP, indicating that the environmentally friendly PBM can be used as an alternative plasticizer to remove the potential health risks from migrating phthalates during applications.     

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.     

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     

Photocrosslinking of azidated poly(vinyl chloride) coated onto plasticized PVC surface: Route to containing plasticizer migration

The migration of phthalate esters which are commonly employed for plasticizing poly(vinyl chloride) (PVC) is a significant problem in PVC-based medical devices as well as in packaging used for food stuffs and pharmaceuticals. Medical-grade PVC resin was treated with sodium azide in dimethylformamide (DMF) to prepare the azide polymer. The polymeric azide was coated onto the surface of plasticized PVC sheets by dipping in a solution of the polymer in tetrahydrofuran (THF). Crosslinking of the azide polymer was accomplished by irradiating the surface using a 125 W UV lamp for various lengths of time. Migration of the plasticizer di 2-(ethylhexyl phthalate) (DEHP) from coated and uncoated samples was examined in n-hexane at 30°C. It was found that 50–80% reduction in migration of DEHP could be effected from plasticized PVC in comparison with the controls in 72 h by this technique depending on the concentration of the coating solution, coating thickness, azide concentration, and irradiation dose. © 1995 John Wiley & Sons, Inc.     

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.     

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。     

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。     

Poly(vinyl chloride) and wood flour press mould composites: New bonding strategies

In this work, different strategies for improving the association between hydrophilic wood flour surfaces and poly(vinyl chloride) (PVC) hydrophobic surfaces were tested. Three new coupling agents, based on living radical polymerisation (LRP), involving PVC were synthesised and tested in formulations with PVC and wood flour. The melt mixing behaviour was analysed in terms of the torque exerted by the mixing blades and related to the structural properties of the mixture. These products were ground and sheets were produced by press moulding. The composites were characterised by dynamic mechanical analysis. It was found that the use of a new block copolymer poly(vinyl chloride)‐b‐poly(hydroxypropyl acrylate)‐b‐poly(vinyl chloride), prepared by LRP, increases the elastic modulus of the composite, under controlled conditions, involving the use of specific amounts of the copolymer. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

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。     

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.     

Hydrothermic aging of plasticized poly(vinyl chloride): Its effect on the dielectric,thermal, and mechanical properties

Accelerated hydrolytic aging (according to the NFT 5166 method) was performed on samples of poly(vinyl chloride) (PVC) plasticized with dioctylphthalate (DOP) and dinonyladipate (DNA) at different concentration ratios. The aging test consisted of immersing the samples in boiling water at 100°C. The samples were removed from water regularly, that is, every 2 h, for mechanical, thermal, and dielectric characterizations. Thermograms of PVC plasticized with DOP revealed no migration of the plasticizer independent of the concentration used. Moreover, the thermal stability of the samples was not affected by the hydrothermal aging. However, for PVC samples plasticized with DNA, a small amount of the plasticizer migrated from the polymer matrix with a considerable effect on the thermal stability. In fact, the data indicated a decrease in the decomposition temperature from 275 to 225°C, particularly for samples containing 50% (w/w) DNA immersed up to 10 h. The mechanical results showed that for a plasticizer content greater than 30% (w/w), the strain at break obtained for samples plasticized with DNA was lower than that for samples plasticized with DOP because the DNA molecules were more likely to be removed by water on account of their polarity and dimension. Finally, the dielectric measurements showed that the permittivity of all the PVC samples plasticized with DOP and immersed in boiling water was higher than that of the virgin samples. On the contrary, the permittivity of the aged unplasticized PVC was less than that of the nonimmersed samples. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 3447–3457, 2003     

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     

Enhanced properties of polyvinyl chloride modified by graphene reinforced thermoplastic polyurethane

Graphene sheets with a range of unusual properties and thermoplastic polyurethane (TPU ) were combined to modify polyvinyl chloride (PVC ), and the enhanced properties such as flexibility, thermal stability and mechanical properties of the PVC were investigated. In order to avoid the C ? Cl bonds in PVC being weakened, graphene was incorporated into TPU in the melting state first and then this TPU was employed as a modifier to enhance and plasticize PVC in another melt blending step. In comparison with the ternary blending method, this step‐by‐step melt blending method was more efficient and convenient. The distribution of graphene sheets in the polymer matrix is uniform and no C ? Cl bond weakened effect can be observed. Due to the similar polarity, TPU showed good compatibility with PVC and its plasticizing effect allowed a broader range of low temperature flexibility of the modified PVC matrix. Moreover, other properties of the resultant PVC matrix (PTG ‐x ) including mechanical properties, thermal stability and plasticizer migration resistance were all found to be improved. With innovative applications in mind, the development of new graphene‐based materials will certainly lead to many future advances in science and technology. © 2017 Society of Chemical Industry     

n‐Butyl acrylate based latex interpenetrating polymer networks used as processing modifiers and impact modifiers of poly(vinyl chloride)

A latex interpenetrating polymer network (LIPN), consisting of poly(n‐butyl acrylate), poly(n‐butyl acrylate‐co‐ethylhexyl acrylate), and poly(methyl methacrylate‐co‐ethyl acrylate) and labeled PBEM, with 1,4‐butanediol diacrylate as a crosslinking agent was synthesized by three‐stage emulsion polymerization. The initial poly(n‐butyl acrylate) latex was agglomerated by a polymer latex containing an acrylic acid residue and then was encapsulated by poly(n‐butyl acrylate‐co‐ethylhexyl acrylate) and poly(methyl methacrylate‐co‐ethyl acrylate). A polyblend of poly(vinyl chloride) (PVC) and PBEM was prepared through the blending of PVC and PBEM. The morphology and properties of the polyblend were studied. The experimental results showed that the processability and impact resistance of PVC could be enhanced considerably by the blending of 6–10 phr PBEM. This three‐stage LIPN PBEM is a promising modifier for manufacturing rigid PVC. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 1168–1173, 2004