In vitro investigation of the effect of plasticizers on the blood compatibility of medical grade plasticized poly (vinyl chloride)

This paper reports the results of an in vitro investigation into the blood response of medical grade poly (vinyl chloride) (PVC), and two types of plasticized PVC in tubing or sheet form, with di-(2-ethylhexyl)phthalate (DEHP) and di(isononyl) cyclohexane-1,2-dicarboxylate (HEXAMOLL^® DINCH) as plasticizer, were selected for assessment of complement activation, coagulation system and platelet activation. The results of the study show that not only the plasticizers at PVC surface have an influence on complement activation, but also the incubation condition such as incubation time and the diameter of PVC tubing. Under static status, C3a, C5a and SC5b-9 concentration in the blood were higher after contacting with PVC plasticized with DEHP (PVC1) than after contacting with PVC plasticized with DINCH (PVC2). However, under dynamic circulation, the results were totally converse, which may be due to smaller diameter and higher shear rate of PVC2. In addition, there was a significant increase of activated partial thrombin time (APTT) and decrease of FIX concentration after plasma contacting with the PVC tubing, which indicated that the intrinsic pathway may be impacted when blood contacted with PVC tubing. However, there was no significant difference of APTT, FIX concentration and CD62p expression rate between the two materials. Moreover, the migration in the DINCH system was considerably lower than for DEHP, which indicates that DINCH could be a promising alterative plasticizer of DEHP.     

Blood response to plasticized poly(vinyl chloride): dependence of fibrinogen adsorption on plasticizer selection and surface plasticizer level

The high level of plasticizer in plasticized poly(vinyl chloride) (PVC) ensures that plasticizer selection has an important influence on the suitability of PVC to function in blood-contacting applications. In this study, three types of plasticized PVC in sheet form, with di-(2-ethylhexyl)phthalate (DEHP), tri-(2-ethylhexyl)trimellitate (TEHTM) and n-butyryltri-n-hexyl citrate (BTHC) as plasticizer, were selected for assessment and single solute fibrinogen adsorption was utilized as an initial index of interactions with blood components. Fibrinogen adsorption behavior shows a strong dependence on the plasticizer selection, plasticizer level at the surface and the adsorption conditions, such as adsorption time and fibrinogen solution concentration. Results indicate that BTHC plasticized PVC possesses the lowest adsorption capacity in the three types of plasticized PVC, while TEHTM plasticized PVC seems to have the strongest reactivity in certain fibrinogen solution concentrations. The alteration of surface plasticizer level was achieved by a methanol-cleaning treatment with a variety of cleaning times and the fibrinogen adsorption on plasticized PVC decreases with the reduction of surface plasticizer level. The migration behavior of two phthalate esters (DEHP and TEHTM) was evaluated using UV-Spectrophotometer to determine the plasticizer level at the surfaces. In addition, the fibrinogen adsorption mechanism was examined with Freundlich adsorption modeling.     

Blood interactions with plasticised poly (vinyl chloride): influence of surface modification

Surface modification of plasticised poly (vinyl chloride) (PVC), with di-(2-ethylhexyl) phthalate (DEHP) as plasticiser, for the improvement of blood compatibility in potential clinical use such as cardiopulmonary bypass was achieved by heparinisation. The influence of surface modification on blood compatibility was assessed in terms of the influence on fibrinogen and factor XII adsorption in vitro, and the generation of thrombin-antithrombin III complex (TAT) and the complement component C3a, in vitro and ex vivo. Electron spectroscopy for chemical analysis (ESCA) was used to characterise the heparinised surface in order to correlate the surface properties with the blood response. Results indicate that at the plasticised PVC surface there is a higher content of heparin than that of the PVC and the DEHP content is lower than that present at the surface of standard plasticised PVC. The blood compatibility assessment confirms the importance of surface modification for the improvement of blood compatibility.     

P(nBA-co-St)接枝VC反应中的缓聚及复合物结构与性能

采用丙烯酸正丁酯与苯乙烯共聚物P(nBA-co-St)胶乳为种子,通过乳液接枝共聚氯乙烯(VC)制备了P(nBA-co-St)/PVC复合树脂。粒径分析结果表明,PVC已成功地包覆在种子上,从透射电镜照片能清楚分辨出复合粒子具有核壳结构,文中合理解释了在该接枝共聚过程中显现的缓聚现象。动态力学分析结果表明,随着核层共聚物中PSt组分含量增加,复合材料在低温区的力学损耗峰逐渐移向高温方向,纯PnBA核因比PSt组分更易接枝VC,从而显著影响了复合树脂低温区的玻璃化转变温度。试样冲击断面的扫描电镜分析揭示,P(nBA-co-St)原位增韧PVC的机理源于基体的剪切屈服。     

丙烯酸酯乳液在氯乙烯悬浮聚合体系中稳态原位增韧改性

以丙烯酸丁酯(BA)、丙烯酸乙酯(EA)为单体,通过乳液聚合制备了粒径100 nm左右的均相交联共聚乳液(AC),并将其作为氯乙烯悬浮聚合用接枝改性剂,原位接枝共聚和原位共混进行增韧改性,以制备高抗冲复合聚氯乙烯树脂(AC-PVC)。研究了乳化剂种类和EA用量对AC乳液稳定性及乳胶粒粒径的影响,模拟了AC乳液在三氯乙烯悬浮聚合体系中的稳定性,并在20 L高压反应釜中进行了氯乙烯悬浮聚合试验,对不同分散剂用量下所得AC-PVC颗粒形态及力学性能进行了表征。结果表明,反应釜粘釜现象明显改善,粗粒径的AC-PVC比例降低,且AC-PVC的抗冲性能显著提高,最高缺口冲击强度可达普通SG-5型PVC树脂的27倍。     

食品包装用PVC瓶盖垫片中增塑剂DEHP的迁移研究

为了解PVC垫片接触各类食品的安全性,采用气相色谱-质谱联用法研究了PVC垫片中DEHP在乙醇和正己烷中的迁移行为及其影响因素。实验结果表明:随着时间的延长,DEHP的迁出量逐渐增加;PVC垫片厚度越小,DEHP越容易迁出;与乙醇相比,DEHP更容易向正己烷中迁移,PVC垫片应避免接触脂肪类食品。     

Blood interactions with plasticized poly(vinyl chloride): relevance of plasticizer selection

An investigation has been made of blood interactions with plasticized poly(vinyl chloride) (PVC) biomaterials in tubular form, taking into account the influence on the blood response of the polymer, antithrombotic agent, blood condition and test procedure. In vitro and ex vivo procedures were used to achieve a comparison between PVC plasticized with di- (2-ethylhexyl)phthalate (DEHP) and with tri-(2-ethylhexyl)trimellitate (TEHTM). The blood response was monitored in terms of the measurement of fibrinogen adsorption capacity, thrombin–antithrombin III complex (TAT) and the complement component C3a. Surface characterization of the polymers was performed by X-ray photoelectron spectroscopy (XPS). The data obtained indicate that in comparison with DEHP-PVC, there is a higher reactivity for TEHTM-PVC, which correlates with the plasticizer distribution at the polymer surface. © 1999 Kluwer Academic Publishers     

Study of the polyvinyl chloride polymer structure in relation to migration of residual vinyl chloride monomer by inverse gas chromatography

The polyvinyl chloride (PVC) polymer structure was studied using inverse gas chromatography (IGC). The specific retention volume (Vg°) of a vinyl chloride monomer (VCM) probe, as well as the thermodynamic parameters of the interaction between PVC and VCM were calculated. Changes in Vg°, free energy(ΔG°_s), enthalpy (ΔH°_s) and entropy (ΔS°_s) observed as the temperature and the amount of VCM decreased, clearly indicate that the PVC—VCM interaction was both concentration and temperature dependent. The Vg° and thermodynamic parameters also varied with changes in polymer structure. Data were interpreted in terms of the active site hypothesis. Active sites in the PVC matrix strongly bind VCM at low enough concentrations and temperatures. Inferably, migration of VCM from PVC packaging materials containing very low concentrations of residual monomer should be for all practical purposes, essentially zero, particularly at low temperatures.     

Artificial receptor-facilitated solid-phase microextraction of barbiturates

A receptor for barbiturates, N,N'-Bis-[6-(2-ethylhexanoylamino)-pyridin-2-yl]-isophthalamide, was designed to dissolve in plasticizers of poly(vinyl chloride) (PVC). Microextractions using receptor-doped films of PVC were carried out as a function of receptor concentration. The effect of the concentration of the receptor on extraction yield is considerable for barbiturates that have significant binding to the receptor but negligible for very similar molecules that do not bind to the receptor strongly. Thus, it is the receptor's ability in molecular recognition, not its generic ability as an H-bonding cosolvent, that is important. On the other hand, NMR data show that the receptor self-associates. A simple, approximate analysis is given to extract the amount of active receptor from the data. Receptor-enhanced extractions of barbiturates from urine are compared to extractions using a phosphate ester as solvent.     

Effect of plasticizer on the electric-field-induced adhesion of dielectric PVC gels

Four different plasticizers have been used to make the PVC gels: poly(vinyl chloride)–diethyl adipate (PVC–DEA), poly(vinyl chloride)–dibutyl sebacate (PVC–DBS), poly(vinyl chloride)–dioctyl phthalate (PVC–DOP) and poly(vinyl chloride)–dibutyl phthalate (PVC–DBP). The chemical structure and molecular weight of the plasticizers significantly affected the electric-field-induced adhesion of the gels. To explain the variations, the dielectric properties, space charge distributions, tensile properties and Raman spectra of the PVC gels were compared. Aliphatic ester (DEA and DBS) plasticizer-containing PVC gels showed larger electric-field-induced adhesion and dielectric constants than phthalate plasticizer (DBP and DOP)-containing gels. Raman spectroscopy suggested that there were different molecular interactions between PVC and the plasticizers. The dielectric constant and mechanical properties of the PVC gels were determined to be the key factors for determining the electric-field-induced adhesion.     

Conducting poly(vinyl chloride)-<Emphasis Type="Italic">graft</Emphasis>-polythiophene: synthesis,characterization, and materials properties

A novel, and facile strategy for chemical, and electrochemical grafting of polythiophene onto poly(vinyl chloride) (PVC) is reported. For this purpose, a thiophene-functionalized PVC macromonomer was synthesized via a condensation reaction between phenylamine-functionalized PVC, and thiophene-2-carbaldehyde. The resultant macromonomer subsequently used in chemical, and electrochemical oxidation copolymerization with thiophene monomer to afford a poly(vinyl chloride)-graft-polythiophene (PVC-g-PTh) graft copolymer. The PVC-g-PTh obtained was characterized by means of Fourier transform infrared spectroscopy, and its electroactivity behavior was verified under cyclic voltammetric conditions. The electrical conductivities of the synthesized samples were measured using samples in which the conductive materials were sandwiched between two Ni electrodes at room temperature using the four probe technique. Moreover, thermal behaviors of the synthesized polymers were investigated by means of and thermogravimetric analysis.     

Scanning electron microscopy studies on tensile,tear and abrasion failure of plasticized poly (vinyl chloride) and copolyester thermoplastic elastomers

Scanning electron microscopic observations on the tensile, tear and abrasion failure of plasticized poly (vinyl chloride) (PVC) and copdyester (Hytrel 40D) thermoplastic elastomers showed that the patterns developed on the fracture surfaces could be correlated with the strength and type of failure of these materials. Hytrel was found to undergo ductile failure whereas PVC showed shear fracture under tensile stress. The higher tear and abrasion resistances of Hytrel than those of PVC were also manifested by the difference in fracture patterns on the failure surfaces of these samples.     

Radiation grafting of hydrophilic monomers on to plasticized poly(vinyl chloride) sheets

Medical-grade plasticized poly(vinyl chloride) (PVC) sheets were surface modified using gamma-radiation grafting of a combination of hydrophilic monomers based on 2-hydroxyethyl methacrylate (HEMA) and N-vinyl pyrrolidone (NVP). The modified surfaces were evaluated for their surface properties using contact angle measurements, phase-contrast photomicroscopy and scanning electron microscopy. Surface energy calculations of the modified surfaces indicated that the surfaces became highly hydrophilic when grafted with even a 1% (v/v) solution of HEMA-NVP combination in the presence of 0.005m CuSO₄. Migration of the plasticizer di(2-ethylhexyl phthalate) (DEHP) from the grafted sheets was examined in hydrocarbon solvents such as n-hexane, n-heptane and n-octane and in extractant media such as cotton seed oil and polyethylene glycol-400 (PEG-400). The migration from modified sheets was found to be <4% of the migration from unmodified control sheets in hydrocarbon solvents at 30° C over a period of 5 h. Accelerated leaching studies in cotton seed oil and PEG-400 demonstrated that virtually no plasticizer migrated out in the former over a period of 96 h whereas the rate of migration in the latter medium showed only a mild reduction. The migration behaviour was Fickian in nature for grafted sheets. The method described may be useful as a simple, versatile technique for preventing plasticizer migration from plasticized PVC for medical applications.     

有机锑和添加剂对聚氯乙烯热稳定性能的协同效应

采用HAAKE流变仪研究了在添加自制有机锑热稳定剂及各种助剂后的硬质聚氯乙烯(PVC)的热稳定性能,同时探讨了它们的防初期着色性能。结果表明:随着有机锑稳定剂用量的增加,PVC样品的动态稳定性能和防初期着色都变好;添加对叔丁基邻苯二酚(TBC)时有较好的防初期着色性能和较好的动态稳定性能;硬脂酸钙和有机锑热稳定剂并用有很好的协同效用,但是随着用量增大,PVC的初期颜色会逐渐变深;巯基乙酸异辛酯对初期颜色和长期稳定性能的影响有一个最佳的添加量。     

MPEG-PCL两嵌段共聚物的合成及对PVC的增塑作用

利用开环聚合的方法,以聚乙二醇单甲醚(MPEG)为起始剂开环ε-己内酯(CL)合成了三种不同分子量的MPEG-PCL两嵌段共聚物,并用FT-IR、NMR、GPC等手段对合成产物进行了表征。证实了目标产物的成功合成,测定了各样品的分子量。将MPEG-PCL与PVC用溶液共混法制得复合物,对其玻璃化温度和力学性能进行测量的结果表明,MPEG-PCL共聚物加入PVC后起到明显的增塑作用,共混物较纯PVC玻璃化温度降低、模量下降、断裂伸长率明显增加,添加20%的嵌段聚合物可以得到软质PVC产品,MPEG-PCL共聚物可用作PVC的增塑剂。     

聚氯乙烯/氧化石墨烯薄膜的力学性能和热稳定性能

通过溶液共混法制备了氧化石墨烯(GO)分散均匀的聚氯乙烯(PVC)/GO纳米复合薄膜,研究了薄膜的力学性能和热稳定性能。结果表明,微量GO能大幅度提高PVC的模量和拉伸强度,且保持较高的断裂伸长率。在PVC中添加质量分数为0.12%的GO,PVC的拉伸强度提高63%,杨氏模量提高20%;添加量为0.60%时,PVC的拉伸强度提高125%,杨氏模量提高126%.添加GO还能提高PVC的起始分解温度、最大分解温度以及PVC的成碳量。GO片层具有较高的强度和模量、GO在高分子基体内的均匀分散、GO和PVC之间较强的相互作用、GO与PVC的层状结构,是其力学性能提高的主要原因.     

VAE/PVC-VDC共混乳液的研究

此共混乳液采用乙烯－醋酸乙烯共聚物（ＶＡＥ）乳液和氯乙烯－偏氯乙烯共聚物（ＰＶＣ－ＶＤＣ）乳液以机械共混方法制得。考察了其微观形态、流变性及其成膜后的力学性能等，发现共混乳液具有一定的相容性，其拉伸强度与ＶＡＥ胶膜相比有很大的提高。     

Poly(ethylene glycol) enhanced dehydrochlorination of poly(vinyl chloride)

Poly(ethylene glycol) (PEG), an environment-friendly reaction medium, has been adopted to accelerate the dehydrochlorination of poly(vinyl chloride) (PVC). Experimental results demonstrated that at 210 degrees C for 1h the dechlorination degree was as high as 74.2% for PVC/PEG, while for PVC only 50.0%. Moreover, from thermogravimetric analysis, it was found that for PVC/PEG the decomposition of PVC corresponding to the dehydrochlorination stage shifted to lower temperatures compared with that of pure PVC, suggesting some interactions exist between PEG and PVC that caused the faster dehydrochlorination rate. In addition, during this process, no waste byproducts such as KCl have been produced, and satisfactory recyclability of PEG (10 cycles) has been obtained.     

Enhanced Mechanical Properties of Multi-layer Graphene Filled Poly(vinyl chloride) Composite Films

In order to improve mechanical properties of soft poly(vinyl chloride)(PVC) films,we used commercial multi-layer graphene(MLG) with large size and high structural integrity as reinforcing fillers,and prepared MLG/PVC composite films by using conventional melt-mixing methods.Microstructures,static and dynamic mechanical properties of the MLG/PVC composite films were investigated.The results showed that a small amount of MLG loading could greatly increase the mechanical properties of the MLG/PVC composites.The tensile modulus of the 0.96 wt%MLG/PVC composites was up to 40 MPa,increasing by31.3%in comparison to the neat PVC.Such a significant mechanical reinforcement was mainly attributed to uniform dispersion of the large-size MLG,good compatibility and strong interactions among MLG and plasticizers and PVC.     

analysis of phthalate ester content in poly(vinyl chloride) plastics by means of fourier transform Raman spectroscopy

Fourier transform (FT) Raman spectroscopy is applied to a range of phthalate ester plasticizers in pure form as well as in poly(vinyl chloride) (PVC) samples. It is found that phthalate esters as a group can be identified by a set of six characteristic Raman bands. FT-Raman spectra of 22 phthalate esters are given. It is demonstrated that the presence of phthalate esters in PVC products is readily detectable by FT-Raman spectroscopy. By use of proper reference samples quantitative determination of the phthalate ester content becomes possible as well.