Unmodified Polyvinyl Chloride Research Articles

Effect of polycarbonate‐polydimethylsiloxane block copolymer and two commercial toughening agents on the flame retardancy and smoke emission of rigid polyvinyl chloride

AbstractIn this work, different test methods were used to investigate the flame retardancy and smoke emission of polyvinyl chloride (PVC) toughened with polycarbonate‐polydimethylsiloxane block copolymer (PC‐b‐PDMS) and two other commercial toughening agents. The oxygen index result and heat release curves in the cone calorimetry test showed that toughened PVC has reduced flame retardancy compared to unmodified PVC. However, the vertical combustion test showed that all samples have achieved the highest flame retardant rating, indicating that the flame resistance of these toughened PVC is still adequate for use. In terms of smoke emission, the results of the cone calorimetry test and the smoke density test showed a significant difference. In the smoke density test, it was found that PVC toughened with PC‐b‐PDMS has less smoke generation in the early stage of combustion. In the cone calorimetry test, the total smoke production was lower for PVC and significantly higher for toughened PVC. This difference was mainly due to the different test conditions of these two tests.

Hydrophilic polymer‐coated PVC surface for reduced cell and bacterial adhesions

Hydrophilic polymers are very useful in biomedical applications. In this study, biocompatible polyethylene glycol (PEG) and polyvinylpyrrolidone (PVP) polymers end-capped with succinimidyl groups were either modified or synthesised and attached to polyvinylchloride surfaces. The modified surfaces were evaluated with cell adhesion and bacterial adhesion. 3T3 mouse fibroblast cells and three bacteria species were used to evaluate surface adhesion activity. Results showed that the modified surface exhibited significantly reduced 3T3 cell adhesion with a 50%–69% decrease for PEG and a 64%–81% for PVP, as compared to unmodified polyvinylchloride. The modified surface also showed significantly reduced bacterial attachment with 22%–78%, 18%–76% and 20%–75% decrease for PEG and 22%–76%, 18%–76% and 20%–73% for PVP to Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa, respectively, as compared to unmodified polyvinylchloride. It seems that an appropriate chain length or molecular weight (neither the longest nor the shortest chain length) determines the lowest cell and bacterial adhesion in terms of PEG. On the other hand, a mixture of polymers with different chain lengths exhibited the lowest cell and bacterial adhesion in terms of PVP.

Effect of Polyvinyl Pyrrolidone on Polyvinyl Chloride-Graft-Acrylamide Membranes

Polyvinyl-chloride (PVC) was dehydrochlorinated by alkaline-solution (NaOH) in determining molarity (3.0 M) followed by grafting with acrylamide (AM) monomer onto dehydrochlorinated PVC (DHPVC) backbone by free-radical graft copolymerization to produce new grafted polymer referred as graft 3M. Then investigated the effect of polyvinyl pyrrolidone (PVP) addition on the grafted polymer. Membranes from pure PVC, graft 3M, and graft 3M/ PVP were synthesis via a phase inversion method. The successful AM grafting onto PVC was confirmed by characterization of the membranes by Atomic Force Microscopy (AFM) and Field Emission Scanning Electron Microscope (FESEM) analysis, porosity, pore size, and contact angle measurements. The new synthesis (graft 3M) and (graft 3M/ PVP) membranes show excellent hydrophilicity in compared to pure PVC membranes, confirmed by higher pure water flux (PWF). The graft 3M/ 3wt.% PVP membrane exhibited the highest pure water permeate flux was about 540 L/m2 h at 28 °C of feed temperature and 1bar of pressure, i.e. was improved by about 270 times compared to the unmodified PVC membrane and 2.35 times compared to the graft 3M membrane.

Preparation, Performance Test, and Microstructure of Composite Modified Reinforced Concrete

To investigate whether the compound modification means which mixes modified Polyvinyl chloride (PVC) aggregate and polypropylene fiber in concrete could gain “positive hybrid effect” and cope with more sophisticated engineering circumstances, four groups of test specimens were prepared: concrete doped with unmodified PVC aggregate, concrete doped with modified PVC aggregate, concrete doped with unmodified PVC aggregate and polypropylene fiber, and concrete doped with modified PVC aggregate and polypropylene fiber. The fiber content is 0.9 kg/m3, the modified solution content is 1 mol/L NaOH, and the replacement amount of PVC fine aggregate in replacement sand is 0%, 5%, 10%, 20%, and 30%. Mechanical property and durability tests were carried out to compare and analyze the measured compressive strength, splitting tensile strength, flexural tensile strength, water absorption rate, and impact failure energy. Moreover, scanning electron microscopy and XRD diffraction were used to analyze micromorphology and crystal structure of concrete. The test results demonstrate that as the content of PVC aggregate increases, the compressive strength, splitting tensile strength, and flexural tensile strength of the concrete decrease significantly, while the brittleness is improved. Meanwhile, the water absorption rate increases and the impact resistance shows an approximately linear increase trend. Under the same content of PVC aggregate, the most effective way to improve compressive strength is to use modified PVC aggregate. The rapid decrease of compressive strength caused by PVC aggregate can be effectively delayed by doping polypropylene fiber and modified PVC aggregate. Adding polypropylene fiber or using the modified PVC aggregate can improve the brittleness, tensile strength, flexural tensile strength, and impact resistance, but they have different modification and reinforcement effects. The concrete prepared by doping polypropylene fiber and modified PVC aggregate has better performance in tensile strength, flexural tensile strength, brittleness, and impact resistance, and the water absorption and the compressive strength of the concrete are enhanced compared with the normal group. Therefore, composite modified reinforced concrete doped with modified PVC aggregate‐polypropylene fiber has broad application prospects.

Polyvinylchloride surface with enhanced cell/bacterial adhesion-resistant and antibacterial functions.

This study reports synthesis and attachment of a novel antibacterial and hydrophilic polymer onto a polyvinylchloride surface via a simple and mild surface coating technique. The compound 3,4-dichloro-5-hydroxy-2(5H)-furanone was derivatized and copolymerized with N-vinylpyrrolidone. The copolymer was then covalently coated onto polyvinylchloride surface. 3T3 mouse fibroblast cells and bacterium Pseudomonas aeruginosa were used to evaluate surface adhesion and antibacterial activity. Results showed that the polymer-modified polyvinylchloride surface not only exhibited significantly decreased 3T3 fibroblast cell adhesion with a 64-84% reduction but also demonstrated significantly decreased P. aeruginosa adhesion with a 65-84% reduction, as compared to unmodified polyvinylchloride. Furthermore, the modified polyvinylchloride surfaces exhibited significant antibacterial functions by inhibiting P. aeruginosa growth with a 58-80% reduction and killing bacteria, as compared to unmodified polyvinylchloride. These results demonstrate that covalent polymer attachment conferred cell/bacterial adhesion-resistant and antibacterial properties to the polyvinylchloride surface.

Decreased Pseudomonas aeruginosa biofilm formation on nanomodified endotracheal tubes: a dynamic lung model.

Ventilator-associated pneumonia (VAP) is a serious complication of mechanical ventilation that has been shown to be associated with increased mortality rates and medical costs in the pediatric intensive care unit. Currently, there is no cost-effective solution to the problems posed by VAP. Endotracheal tubes (ETTs) that are resistant to bacterial colonization and that inhibit biofilm formation could provide a novel solution to the problems posed by VAP. The objective of this in vitro study was to evaluate differences in the growth of Pseudomonas aeruginosa on unmodified polyvinyl chloride (PVC) ETTs and on ETTs etched with a fungal lipase, Rhizopus arrhizus, to create nanoscale surface features. These differences were evaluated using an in vitro model of the pediatric airway to simulate a ventilated patient in the pediatric intensive care unit. Each experiment was run for 24 hours and was supported by computational models of the ETT. Dynamic conditions within the ETT had an impact on the location of bacterial growth within the tube. These conditions also quantitatively affected bacterial growth especially within the areas of tube curvature. Most importantly, experiments in the in vitro model revealed a 2.7 log reduction in the number (colony forming units/mL) of P. aeruginosa on the nanoroughened ETTs compared to the untreated PVC ETTs after 24 hours. This reduction in total colony forming units/mL along the x-axis of the tube was similar to previous studies completed for Staphylococcus aureus. Thus, this dynamic study showed that lipase etching can create surface features of nanoscale roughness on PVC ETTs that decrease bacterial attachment of P. aeruginosa without the use of antibiotics and may provide clinicians with an effective and inexpensive tool to combat VAP.

An investigation on 4-aminobenzoic acid modified polyvinyl chloride/graphene oxide and PVC/graphene oxide based nanocomposite membranes

We synthesized graphene oxide (GO) using a modified Hummer’s method, and then blended it into polyvinyl chloride (PVC) and amino-functional PVC (PVC-4ABA) matrices. GO was added to 0.5 g PVC at 0.01, 0.05, 0.1 and 0.5 g. The PVC/GO matrix was modified using 4-aminobenzoic acid (4ABA) at 0.01, 0.05, 0.1 and 0.5 g per 0.5 g PVC. This gave four amino-functional PVC/GO series and one PVC/GO series nanocomposite membranes that were prepared by a solution blending route. The filler and the modifier (4ABA) content effect on the PVC membrane properties were investigated. Fourier transform infrared spectroscopy confirmed the GO functional groups and PVC modification with 4ABA. According to scanning electron microscopy, a unique two-way layered structure was observed for modified PVC and GO composites. XRD explained the conformation of PVC/GO and modified PVC/GO nanocomposites. GO crystallite size and its interlayer distance between sheets were also studied. The XRD peak at 2θ = 10.8° with interlayer spacing of 0.81 nm was calculated with the Bragg equation. GO particle size was calculated (Scherrer formula) as 7.78 nm. XRD results revealed fine interaction between modified PVC and GO compared with unmodified PVC composites. Glass transition temperature (Tg) of non-modified PVC/GO nanocomposite was 202℃, whereas modified nanocomposite with similar GO loading had Tg equal to 212℃. Higher filler content gave better hydrophilic membranes as determined by solvent content, porosity, and shrinkage ratio. PVC-4ABA-0.5/GO 0.5 membrane with a low contact angle (25°) is a fine option for water purification. The overall results suggest that the higher modifier concentrations developed better interaction between the nanofiller and PVC.

Modification of polyvinyl chloride (PVC) membrane for vacuum membrane distillation (VMD) application

In the present work, hydrophobic modification of polyvinyl chloride (PVC) was performed with the introduction of ethyl acrylate (EA) monomer onto the polymer backbone, by free radical graft copolymerization. Membranes from polyvinyl chloride and grafted PVC solutions were prepared via immersion precipitation process for vacuum membrane distillation (VMD) application. The success of EA grafting onto PVC was confirmed by Fourier-transform infrared (FTIR) spectroscopy, and energy-dispersive X-ray spectroscopy (EDX). The membranes were characterized by scanning electron microscopy (SEM) analysis contact angle, pore size and porosity measurements. FTIR data showed that the PEA-g-PVC displayed new absorption peaks, indicating the introduction of the EA ester group on PVC. A significant difference between the spectrum of the PVC and PEA-g-PVC in the peak of chlorine and carbon was observed by using EDX analysis. The EA grafting onto PVC could affect the structural morphology of the PVC-g-PEA membranes, and increase the porosity, largest pore size and contact angle of the prepared membranes, whereas the membrane thickness is reduced. According to the results of VMD process on pure water, the permeate flux of the modified membrane was improved by about 15 times compared to the unmodified PVC membrane. The highest permeate flux of the modified membrane was about 37.5kg/m2h at 60°C of feed temperature and 2mbar of vacuum pressure.

The sulfonation of polyvinyl chloride: Synthesis and characterization for proton conducting membrane applications

Sulfonated poly-vinyl chloride (PVCs) membranes were synthesized first using an ethylenediamine solution to aminate the porous free-standing poly-vinyl chloride (PVC) membrane. This modified PVC was then reacted with sulfuric acid to form the PVCs material. The reaction time was varied to give PVCs materials of different degrees of sulfonation (DS). The membranes were characterized with FTIR and elemental analysis to confirm the presence of a –SO3H group. SEM was used to ensure the morphology had not changed during the reaction. Water-uptake and proton conductivity were measured and it was found that as the reaction time increased, both conductivity and water-uptake of the membranes increased compared to the unmodified PVC material. This study demonstrates a novel technique to impart increased water-uptake and proton conductivity to a PVC polymer without destroying the pre-existing membrane morphology.

Reducing Infections Using Nanotechnology

ABSTRACTVentilator associated pneumonia (VAP) is a serious and costly clinical problem. Specifically, receiving mechanical ventilation for over 24 hours increases the risk of VAP and is associated with high morbidity, mortality and medical costs. Cost effective endotracheal tubes (ETTs) that are resistant to bacterial infection could help prevent this problem. The objective of this study was to determine differences in the growth ofStaphylococcus aureus(S. aureus) on nanomodified and unmodified polyvinyl chloride (PVC) ETTs under dynamic airway conditions. PVC ETTs were modified to have nanometer surface features by soaking them inRhizopus arrhisus,a fungal lipase. Twenty-four hour experiments (supported by computational models) showed that air flow conditions within the ETT influenced both the location and concentration of bacterial growth on the ETTs especially within areas of tube curvature. More importantly, experiments revealed a 1.5 log reduction in the total number ofS. aureuson the novel nanomodified ETTs compared to the conventional ETTs after 24 hours of air flow. This dynamic study showed that lipase etching can create nano-rough surface features on PVC ETTs that suppressS. aureusgrowth and, thus, may provide clinicians with an effective and inexpensive tool to combat VAP.

Diminished adhesion and activation of platelets and neutrophils with CD47 functionalized blood contacting surfaces

CD47 is a ubiquitously expressed transmembrane protein that, through signaling mechanisms mediated by signal regulatory protein alpha (SIRPα1), functions as a biological marker of ‘self-recognition’. We showed previously that inflammatory cell attachment to polymeric surfaces is inhibited by the attachment of biotinylated recombinant CD47 (CD47B). We test herein the hypothesis that CD47 modified blood conduits can reduce platelet and neutrophil activation under clinically relevant conditions. We appended a poly-lysine tag to the C-terminus of recombinant CD47 (CD47L) allowing for covalent linkage to the polymer. SIRPα1 expression was confirmed in isolated platelets. We then compared biocompatibility between CD47B and CD47L functionalized polyvinyl chloride (PVC) surfaces and unmodified control PVC surfaces. Quantitative and Qualitative analysis of blood cell attachment to CD47B and CD47L surfaces, via scanning electron microscopy, showed strikingly fewer platelets attached to CD47 modified surfaces compared to control. Flow cytometry analysis showed that activation markers for neutrophils (CD62L) and platelets (CD62P) exposed to CD47 modified PVC were equivalent to freshly acquired control blood, while significantly elevated in the unmodified PVC tubing. In addition, ethylene oxide gas sterilization did not inhibit the efficacy of the CD47 modification. In conclusion, CD47 modified PVC inhibits both the adhesion and activation of platelets and neutrophils.

Toughening of unmodified polyvinylchloride through the addition of nanoparticulate calcium carbonate and titanate coupling agent

AbstractPVC/CaCO3 polymer nanocomposites of differing compositions were produced using a two‐roll mill and compression molding. In all formulations, 0.6 phr of titanate was incorporated to assist dispersion during processing. The morphology was observed using transmission electron microscopy, and the static and dynamic mechanical and fracture properties were determined. Fracture toughness examination was performed according to strain energy release test method. The presence of nanometer‐sized CaCO3 particles led to a slight decrease in the tensile strength but improved the impact energy absorption, storage modulus, and fracture toughness. The use of titanate coupling agent softened the polymer matrix and reduced the matrix's modulus. Fracture surface examinations by scanning electron microscopy showed that the coupling agent improved particle–matrix bonding and inhibited void formation around the particles. Finite element analysis suggested that the improved particle–matrix bonding reduced the matrix's plasticity around the particles, which decreased the toughening efficiency of the composites. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

Superhydrophobic, nanotextured polyvinyl chloride films for delaying Pseudomonas aeruginosa attachment to intubation tubes and medical plastics

Bacterial attachment onto the surface of polymers in medical devices such as polyvinyl chloride (PVC) is influenced by the physicochemical properties of the polymer, including its surface hydrophobicity and roughness. In this study, to prevent biofilm formation onto PVC devices, the PVC surface was modified using a combination of solvent (tetrahydrofuran) and non-solvents (i.e. ethanol and methanol). The surface of unmodified PVC was smooth and relatively hydrophobic (water contact angle (CA)=80°). Ethanol-treated PVCs revealed the presence of micron-sized particulates and porous structures as the concentration of ethanol was increased. Surface hydrophobicity (measured in terms of CA) increased from 73° to 150° as the ethanol concentration increased from 15% to 35% (v/v). In general, methanol-treated PVCs were more hydrophilic compared to those treated with ethanol. The colonization of Pseudomonas aeruginosa PAO1 onto unmodified PVC surface was rapid, and individual bacterial cells could be seen after 6h incubation. On the surface of treated PVC, the secretion of extracellular matrix layers was evident at 18h and P. aeruginosa PAO1 start to form microcolonies at 24h of incubation. The initial attachment of P. aeruginosa PAO1 was delayed to 18 and 24h, respectively in the PVCs treated with 25% (v/v) and 35% (v/v) ethanol. It can be concluded that the treatment used in this study to prepare superhydrophobic PVC surface prevented the colonization of bacteria up to 24h after culture.

Decreased Staphylococcus aureus biofilm formation on nanomodified endotracheal tubes: a dynamic airway model

Ventilator-associated pneumonia (VAP) is a serious and costly clinical problem. Specifically, receiving mechanical ventilation for over 24 hours increases the risk of VAP and is associated with high morbidity, mortality, and medical costs. Cost-effective endotracheal tubes (ETTs) that are resistant to bacterial infections could help prevent this problem. The objective of this study was to determine differences in the growth of Staphylococcus aureus on nanomodified and unmodified polyvinyl chloride (PVC) ETTs under dynamic airway conditions simulating a ventilated patient. PVC ETTs were modified to have nanometer surface features by soaking them in Rhizopus arrhisus, a fungal lipase. Twenty-four-hour experiments (supported by computational models) showed that airflow conditions within the ETT influenced both the location and the concentration of bacterial growth on the ETTs, especially within areas of tube curvature. More importantly, experiments revealed a 1.5 log reduction in the total number of S. aureus on the novel nanomodified ETTs compared with the conventional ETTs after 24 hours of airflow. This dynamic study showed that lipase etching can create nanorough surface features on PVC ETTs that suppress S. aureus growth, and thus may provide clinicians with an effective and inexpensive tool to combat VAP.

Nanomodified Endotracheal Tubes: Spatial Analysis of Reduced Bacterial Colonization in a Bench Top Airway Model

ABSTRACTVentilator associated pneumonia (VAP) is a serious and costly clinical problem. Specifically, receiving mechanical ventilation for over 24 hours increases the risk of VAP and is associated with high morbidity, mortality and medical costs. Cost effective endotracheal tubes (ETTs) that are resistant to bacterial infection could help prevent this problem. The objective of this study was to determine differences in the growth ofStaphylococcus aureus(S. aureus) on nanomodified and unmodified polyvinyl chloride (PVC) ETTs under dynamic airway conditions. PVC ETTs were modified to have nanometer surface features by soaking them inRhizopus arrhisus,a fungal lipase. Twenty-four hour experiments (supported by computational models) showed that air flow conditions within the ETT influenced both the location and concentration of bacterial growth on the ETTs especially within areas of tube curvature. More importantly, experiments revealed a 1.5 log reduction in the total number ofS. aureuson the novel nanomodified ETTs compared to the conventional ETTs after 24 hours of air flow. This dynamic study showed that lipase etching can create nano-rough surface features on PVC ETTs that suppressS. aureusgrowth and, thus, may provide clinicians with an effective and inexpensive tool to combat VAP.

The effects of water and frequency on fatigue crack growth rate in modified and unmodified polyvinyl chloride

AbstractA study of the influence of water environments on the cyclic fatigue crack behavior of polyvinyl chloride (PVC), with (PVC‐M) and without (PVC‐U) chlorinated polyethylene (CPE) impact modifier was undertaken and compared with corresponding results in air. Two frequencies of 1 and 7 Hz were applied to assess the influence of frequency on the fatigue behavior; a higher fatigue resistance and threshold were obtained with increasing frequency. This trend is more significant in water. However, in this environment, the fatigue resistance deteriorated under conditions of higher stress intensity factor amplitude (ΔK) and frequency. The fatigue properties of PVC‐U are the most affected by the presence of water, particularly at low frequency and higher ΔK. Examination of the fracture surface showed the interaction of water molecules and the PVC matrix with the formation of (1) a nodular structure, close to the fatigue threshold and (2) plasticized structures at high ΔK, which are associated with a greater threshold value and fatigue resistance. The absorption of the water retarded the fibrillation of craze and caused crack blunting effects. Water functions as a plasticizer, particularly at high ΔK, through the formation of the plasticized structures. Results are compared with those observed from an in‐service failure. POLYM. ENG. SCI., 2009. © 2009 Society of Plastics Engineers

Toughening of unmodified polyvinylchloride through the addition of nanoparticulate calcium carbonate

PVC/CaCO3 polymer nanocomposites of differing compositions were produced using a two-roll mill and compression molding. The morphology was observed using transmission electron microscopy, and the static and dynamic mechanical and fracture properties determined. The presence of nanometer-sized CaCO3 particles led to a slight decrease in the tensile strength but improved the impact energy, the storage modulus and the fracture toughness. Fracture surface examination by scanning electron microscopy indicated that the enhanced fracture properties in the nanocomposites were caused by the assisted void formation at the particles. This hypothesis is supported by a microstructure-based finite element modeling based upon elastic–plastic deformation around a weakly bonded particle. Hence, this provides an explanation of both the uniaxial tensile behavior and enhanced toughness of the nanocomposites.

The effects of frequency on fatigue threshold and crack propagation rate in modified and unmodified polyvinyl chloride

AbstractThe cyclic fatigue crack behavior of polyvinyl chloride (PVC), with (PVC‐M) and without (PVC‐U) chlorinated polyethylene (CPE) impact modifier, was studied. The effect of impact modifier upon fatigue crack growth rate and threshold was evaluated at frequencies of 1, 7, and 20 Hz. It was shown that the addition of CPE lowered the threshold stress intensity factor amplitude for crack growth (ΔKth) of PVC‐M compared to that of PVC‐U at lower frequencies, and that the effect became more pronounced at lower frequency. At lower stress intensity factor amplitudes (below ΔK = 1 MPa·m1/2), there was a slight difference between the crack growth rates of U‐ and M‐PVC. The crack advance mechanism is investigated by microscopic observation of the crack tip process zone. Although the zone is relatively large in PVC‐M, associated with higher toughness, it did not improve the fatigue crack growth resistance significantly. Fracture surface observations reveal a higher density of fibrils on the fatigued surface of PVC‐M with the density, relative to that observed in PVC‐U, reducing with frequency. It is therefore hypothesized that accelerated fibril failure is a mechanism of fatigue. POLYM. ENG. SCI., 2009. © 2009 Society of Plastics Engineers

Immobilized heparin inhibits the increase in leukocyte surface expression of adhesion molecules.

The effect of heparin coating of artificial materials on the surface expression of leukocyte surface molecules was assessed in blood from 9 donors in an experimental model of extracorporeal circulation. The leukocyte surface molecules CD11b, complement receptor type 3 (CR3), and CD45, leukocyte common antigen (LCA), on granulocytes and monocytes exposed to unmodified polyvinyl chloride tubes increased significantly compared with unmanipulated controls (p < 0.001) whereas a very modest and nonsignificant increase was observed in blood circulated in heparin-coated tubes. Accordingly, a highly significant reduction in expression of the 2 molecules was achieved by heparin coating (p < 0.001). The expression of CD11b and CD45 correlated with the degree of complement activation in plasma (rho = 0.6, p = 0.003). The expression of CD14 (endotoxin receptor) and CD16 (Fc gamma III receptor) was increased to the same extent in blood from unmodified and heparin-coated tubes (p < 0.02), and no correlation to complement activation was seen (rho = -0.275, p = 0.17 and rho = -0.004, p = 1, respectively). In conclusion, heparin coating of artificial surfaces has a substantial effect, reducing the expression of molecules involved in cellular adhesion and activation (CD11b and CD45), and the increase of these molecules by unmodified surfaces is complement dependent. In contrast, up-regulation of other surface molecules (CD14 and CD16) seems to be independent of heparin coating and complement activation and, thus, might be regulated by other mechanisms.