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Results for “Polyethylene Terephthalates”

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PubMed1995

Platelet and coagulation factor variations induced in vitro by polyethylene terephthalate (Dacron) coated with pyrolytic carbon.

The haemocompatibility of polyethylene terephthalate (Dacron) coated with pyrolytic carbon was examined in vitro, evaluating its capability of inducing adhesion and platelet activation, and of modifying the intrinsic coagulation pathway. Platelet adhesion was evaluated by counting platelets before and after in vitro contact of human plasma with the material under examination. Platelet activation was evaluated by determining platelet factor 4 (PF4) and thromboxane B2. Intrinsic coagulation pathway alterations were studied by determining activated partial thromboplastin time (APTT) and the activity of single factors. The results obtained show that pyrolytic carbon-coated Dacron induces platelet adhesion, reduction in platelet volume and lower increase in thromboxane production than that obtained after contact with uncoated Dacron. Pyrolytic carbon-coated Dacron does not induce PF4 release, contrary to uncoated Dacron induces a significant release. Moreover, pyrolytic carbon-coated Dacron, induces a significant extension of APTT by reducing the activity of intrinsic pathway factors, particularly factor XI.

Biocompatible Materials↗

PubMed1980

Controlled microstructure of two stage polyhydroxyethyl methacrylate coatings on polyethylene terephthalate substrates for potential prosthetic applications.

Two types of polyethylene terephthalate (Dacron) substrates (USCI DeBakey Vasculour-D and USCI Sauvage filamentous) have been selectively coated with Poly-hydroxyethyl methacrylate (P-HEMA) in a two-stage process. Using scanning electon microscopy (SEM) techniques, the microstructural details of the fabrications were identified. The first stage of this process imparted a coating of P-HEMA having a heterogeneous macroporous structure and the second stage yielded an internal surface coating of hydrogel with a homogeneous microporous surface structure. The morphology on a colloidal level was controlled by adjustment of the cosolvent ratios holding other fabrication parameters constant. These microstructural features coupled with the chemical properties of the hydrogel suggest potential medical prosthetic applications. The results of initial canine carotid artery implantations indicate that an endothelial-like cell layer can be established within 21 days on the luminal surface of specific hydrogel impregnated Dacron knitted prosthetic materials. The chemical and morphological properties of a hydrogel impregnated Dacron prosthesis may present a blood flow surface which allows proper conditioning protein and cellular deposition leading to an accelerated endothelial development without the need to preclot the prosthesis wall.

Acrylates↗

PubMedDate not supplied

Evaluation of polyethylene terephthalate cyclic trimer migration from microwave food packaging using temperature-time profiles.

The polymer polyethylene terephthalate (PET) is widely used for packaging food that will be heated or cooked in the PET container. A procedure was developed to predict the potential of PET to migrate from the container into the food. Migration experiments using crystallized polyethylene terephthalate (CPET) and corn oil were performed at 115, 146 and 176 degrees C. From these experiments diffusion coefficients were calculated for the cyclic trimer in PET. By using an Arrhenius plot to obtain the diffusion coefficient and a temperature versus time plot of a microwave susceptor-heated CPET tray, it was possible to predict migration of the cyclic trimer into corn oil under microwave conditions. Predicted values were in good agreement with measured results.

Diffusion↗

PubMed2005

[Metals in recycled polyethylene terephthalate and discrimination method for its use].

Metals in recycled polyethylene terephthalate (PET) were analyzed by ICP-MS following microwave digestion with nitric acid. Physically and superclean-like recycled PET contained both Ge and Sb, and sometimes contained Co, P or Si. In contrast, the chemically recycled PET contained only Ge or Sb, and some samples contained Co. The recycled PETs did not contain Pb or Cd. Ge and Sb were catalysts of the polymerization, and the other metals also originated from the PET resin as additives. It was concluded that there is no safety concern about metals in recycled PET. It became clear that the presence of both Ge and Sb could identify products formed using physically or superclean-like recycled PET. According to this discrimination method, about half of the sheet molding products used recycled PET.

Antimony↗

PubMed1993

Association of polyacrylamide beads to polyethylene terephthalate prostheses.

A method for the coupling of polyacrylamide beads to polyethylene terephthalate (PET) vascular prostheses is described. The reactional procedure used is performed along several steps; acrylic acid grafting on PET textile fibres, in order to introduce reactive carboxylic groups, introduction of terminal primary amine groups onto the beads, and then, attachment method which consists in coupling carboxylic groups of prostheses with amine groups of modified beads. The relative weight increase of the samples before and after the coupling reaction and, microscopic observations of beads distribution onto the prostheses surface demonstrate the binding feasibility of polyacrylamide matrices to PET prostheses. In the near future, authors expect to replace these beads by microcapsules with polyacrylamide wall and containing active compounds to improve the vascular prostheses biocompatibility.

Acrylic Resins↗

PubMed2001

In vitro studies of platelet adhesion on laser-treated polyethylene terephthalate surface.

In order to improve blood compatibility, the surfaces of polyethylene terephthalate (PET) were treated using CO2 pulsed and KrF excimer lasers. The physico-chemical characterization of the laser-treated PET surfaces was carried out through attenuated total reflectance infrared spectroscopy and contact-angle measurements. The hemocompatibility of the laser-irradiated PET films was examined in vitro to evaluate their capability of inducing platelet adhesion in comparison with unmodified PET. The number of adhered platelets was determined by lactate dehydrogenase (LDH) activity measurement. Platelet adhesion on the untreated PET was relatively high compared to the laser-treated samples. Laser irradiation of PET surface reduced the number of adherent platelets and prevented platelet spreading on the surface. Reduction of platelet adhesion was attributed to the change in morphology, chemical structure, and crystallinity of the PET surface due to laser irradiation with various numbers of pulses. The morphology of adhered platelets on the PET surfaces was investigated by scanning electron microscopy (SEM). The SEM observations were consistent with the results obtained from LDH activity measurement.

Biocompatible Materials↗

PubMed2001

Interleukin-6 expression by cultured human endothelial cells in contact with carbon coated polyethylene terephthalate.

In order to evaluate if carbon coated polyethylene terephthalate (C-PET) could favor inflammatory reactions, the expression of interleukin-6 (IL-6) by cultured human umbilical vein endothelial cells was tested in vitro. The cultures were put in contact with C-PET for 1, 24, 48 and 72 h. The same cells cultured on tissue culture-treated polystyrene without biomaterials were tested as the negative control; the same cells incubated with LPS were the positive control. The level of IL-6 in the conditioned medium was tested by enzyme immunoassay; the mRNA expression was evaluated by RT-PCR with specific primers. The cultures incubated with C-PET produced non significantly different amount of IL-6 compared to the negative control and did not induce the expression of IL-6 specific mRNA. LPS induced a significantly higher release of IL-6 in the medium and the expression of mRNA after 24, 48 and 72 h. We conclude that C-PET does not stimulate the synthesis of IL-6 and therefore does not favor inflammatory reaction through the release of this cytokine.

Journal Article↗

PubMed1980

Migration of ethylene glycol from polyethylene terephthalate bottles into 3% acetic acid.

Migration of ethylene glycol (EG) from polyethylene terephthalate (PET) bottles into the food simulate 3% acetic acid was studied using 32 fluid oz PET bottles filled with 3% acetic acid and stored at 32 degrees C for 6 months. Final concentration of EG in the 3% acetic acid migration solution was about 100 ppb, which is equivalent to about 94 microgram EG/bottle. A gas-liquid chromatographic procedure for quantitating EG was developed which is capable of measuring EG levels as low as 50 ppb in the migration solution.

Acetates↗

PubMed2006

Migration of formaldehyde and acetaldehyde into mineral water in polyethylene terephthalate (PET) bottles.

The levels of formaldehyde (FA) and acetaldehyde (AA) in polyethylene terephthalate (PET) bottles and in commercial mineral water are reported. All the water samples bottled in Japan contained detectable levels of FA (10.1-27.9 microg l(-1)) and AA (44.3-107.8 microg l(-1)). Of 11 European bottled water samples, eight did not contain either FA or AA, while the remaining three had detectable levels of FA (7.4-13.7 microg l(-1)) and AA (35.9-46.9 microg l(-1)). In three North American bottled water samples, two contained FA (13.6 and 19.5 microg l(-1)) and AA (41.4 and 44.8 microg l(-1)), and one did not. Regardless of the region of origin, all the sterilized water samples contained FA and AA, whilst in contrast, none of the unsterilized water without carbonate contained FA or AA. Of the carbonated water samples, three contained FA and AA, and one did not. When fortified with FA and AA, the commercial water sample without otherwise detectable FA and AA was able to reduce levels, although the commercial water sample containing FA and AA could not. The presence of bacteria in the commercial water samples was investigated using an ATP-based bioluminescent assay and heterotrophic plate count method. The commercial water without FA and AA contained heterotrophic bacteria, whilst the commercial water with FA and AA did not contain detectable bacteria. It is suggested that in this case both FA and AA migrated from PET materials, but were subsequently decomposed by the heterotrophic bacteria in the unsterilized water.

Acetaldehyde↗

PubMedDate not supplied

[The migration of acetaldehyde from polyethylene terephthalate bottles for fresh beverages containing carbonic acid].

The migration of acetaldehyde from polyethylene terephthalate (PET) under various conditions was analysed by headspace gas chromatography and flame ionisation detection. The residual amounts of new PET bottles were about 6.3 mg/kg with a migration value of 200 micrograms/l. On studying the migration at different temperatures and times, behaviour curves characteristic of packing materials made from plastics are obtained. The amount of acetaldehyde diffusing from PET at a temperature of 40 degrees C reached a constant level after 4 days which was about 10% of the residual value of acetaldehyde. On increasing the temperature by 20 degrees C, this level was raised up to 50%. The results of the analysis of acetaldehyde in soft drinks containing carbonic acid show that the migration in fact is not sufficiently high to influence the taste of these soft drinks. A negative effect on the taste may be recognized with mineral waters and soda when they are exposed to higher temperatures (e.g. 40 degrees C or more) over a longer period of time.

Acetaldehyde↗

PubMed2003

Evaluation of some screening methods for the analysis of contaminants in recycled polyethylene terephthalate flakes.

A range of different analytical techniques were used to test recycled polyethylene terephthalate (PET) flakes for potential chemical contaminants. The techniques used were headspace gas chromatography coupled to mass spectrometry (GC-MS), liquid extraction followed by GC-MS, supercritical-fluid extraction followed by GC-MS, and migration testing followed by elemental analysis using inductively coupled plasma mass spectroscopy (ICP-MS). The PET samples were 50 representative samples taken from 600 that had been collected throughout Europe and which had been screened for potential contaminants using a single technique of high-temperature GC-MS. Six of the 50 samples tested had been spiked with a selection of model contaminants, three samples were virgin PET flakes and two of the samples were from supercleaning processes. All samples were analysed 'blind' in this exercise. The qualitative results showed that most of the contaminants came from the first use, being flavour-aroma compounds from soft drinks. The quantitative analysis found concentrations under a few mg kg(-1) in the polymer, except for the spiked samples. Element migrations were low and only calcium, silicon and sodium had median migrations above 50 microg l(-1). This in-depth analysis of recycled PET flakes did not identify any significant contaminants that had not already been detected by the high-temperature static GC-MS screening method, thus demonstrating its utility.

Beverages↗

PubMed1992

Visualization method for fingerprints on skin by impression on a polyethylene terephthalate (PET) semirigid sheet.

Based on the phenomenon that static electricity attracts dust, a polyethylene terephthalate (PET) semirigid sheet coated with printing ink was used to visualize impressions of fingerprints on the skin of living and dead bodies. Compared with visualization methods for perspiration fingerprints, this method recovers better images for a longer time after the fingerprint has been deposited on skin. Fingerprints transferred to the PET sheet are photographed with sidelighting using an ordinary light source. For fingerprints that yield inadequate contrast, an argon-ion laser can be used to improve the contrast.

Dermatoglyphics↗

PubMed1999

Influence of polyethylene terephthalate on the release of growth factors by human endothelial cells.

The influence of polyethylene terephthalate (PET) on the release of platelet derived growth factor AB (PDGF-AB) and basic fibroblast growth factor (bFGF) by in vitro cultured human endothelial cells was assessed by enzyme immunoassay. No significant differences were observed in the production of PDGF-AB with respect to the negative control cultures. A significant increase was observed in the production of bFGF after 48 and 72 h with respect to the negative control cultures. It can be concluded that PET may induce an increase in the production of basic FGF in endothelial cells.

Biocompatible Materials↗

PubMed2000

Cytokine expression in vitro by cultured human endothelial cells in contact with polyethylene terephthalate coated with pyrolytic carbon and collagen.

In order to evaluate whether or not polyethylene terephthalate coated with pyrolytic carbon and collagen (PET+PC) favors inflammatory or hyperplastic reactions, the expression of mRNAs specific for interleukin-6 (IL-6), platelet-derived growth factor-A (PDGF-A), PDGF-B, transforming growth factor-beta1 (TGF-beta1), and TGF-beta2 were tested in vitro by cultured human umbilical vein endothelial cells (HUVEC). The cultures were put in contact with PET+PC for 1, 24, 48, and 72 h. The same cells cultured on polystyrene without biomaterials were tested as negative controls; cultures incubated with LPS were the positive control. The expression of mRNAs was evaluated by RT-PCR with specific primers. PET+PC did not determine any differences in the expression of IL-6-specific mRNA at any of the incubation times compared to the negative control while LPS (the positive control) induced expression after 24, 48, and 72 h. PET+PC induced a more precocious expression of mRNA specific for PDGF-A than did the negative control; however, the expression no longer was present after 48 h while in the negative control the expression stopped after 72 h. PET+PC induced a less frequent expression of PDGF-B-specific mRNA than did the negative control and LPS, especially after 24 h. PET+PC induced a later expression of TGF-beta2-specific mRNA than did the negative control and a less frequent expression of mRNA specific for TGF-beta1 after 24 and 72 h.

Biocompatible Materials↗

PubMed2006

Increase of the hydrophilicity of polyethylene terephthalate fibres by hydrolases from Thermomonospora fusca and Fusarium solani f. sp. pisi.

Treatment of polyethylene terephthalate fibres with hydrolase preparations from Thermomonospora (Thermobifida) fusca and Fusarium solani f. sp. pisi resulted in an increase of the hydrophilicity of the fibres determined by measurement of their dyeing behaviour with reactive dyes and their water absorption ability. Reflectance spectrometry of treated fibres dyed with a reactive dye showed that the colour became more intense corresponding to an increase of hydroxyl groups on the fibre surfaces and indicated a stepwise peeling of the fibres by the enzymes comparable to the effects obtained by alkaline treatments. The synthetic fibres treated with the hydrolase from T. fusca also showed enhanced water absorption ability further confirming the increased surface hydrophilicity caused by the enzyme.

Absorption↗

PubMedDate not supplied

Silver modification of polyethylene terephthalate textiles for antimicrobial protection.

The safety and in vitro effectiveness of applying silver to polyethylene terephthalate fabric mechanical heart valve (MHV) sewing cuffs for the prevention of prosthetic valve endocarditis (PVE) were evaluated. PVE is an infrequent but grave complication of cardiac surgery associated with mortality rates potentially exceeding 50%. A poor response to antibiotic therapy is partly responsible for the high mortality rates. Silver is a well known antimicrobial agent with broad effectiveness. Preliminary in vitro microbial challenge studies of the coated fabric using the New York State 63 bacteriostatic test and Dow Corning Shake Flask test showed a > or = 97% reduction for most organisms tested. Sheep mitral valve replacement studies suggest comparable tissue ingrowth of uncoated and coated fabric with a more organized, thinner pannus formed on silver coated fabric. Low levels of silver were present in the serum at all time periods. These results indicate MHVs with silver coated cuffs may provide additional protection against PVE.

Animals↗

PubMed1990

Effects of polyethylene terephthalate on yeast alcohol dehydrogenase.

Yeast alcohol dehydrogenase (alcohol: NAD+ oxidoreductase, EC 1.1.1.1) was adsorbed onto polyethylene terephthalate, a synthetic polymer. The effects of the polymer on the properties of the enzyme were studied. The specific activity of the bound enzyme on protein basis was only 1.2 per cent of the specific activity of the soluble enzyme. The optimum pH for the catalytic activity was strongly shifted toward acidic direction. The apparent temperature optimum of the bound enzyme was identical with that of the soluble form. The apparent Michaelis constants of the bound enzyme were higher for both ethanol and NAD+. The conformational stability of the enzyme against heat treatment and urea was decreased as a consequence of adsorption.

Adsorption↗

PubMed1998

Gel permeation chromatography (GPC) of repeatedly extruded polyethylene terephthalate (PET).

The paper deals with gel permeation chromatography (GPC) monitoring of the behaviour of PET (polyethylene terephthalate) after repeated extrusions. Virgin PET was submitted to three successive extrusion/drying cycles and then the samples were swelled with hexafluoroisopropanol and treated with chloroform. GPC analysis was carried out at room temperature on a B.C.S. Serial LC 2000 GPC system equipped with a series of four GPC columns with UV detection at 254 nm and chloroform as eluent. GPC results showed that after each extrusion step the molecular weight distribution of the PET was different and Mw, Mn and Mz decreased. These findings suggest that during each extrusion degradation occurs and that repeated extrusions, as in the case of the recycling PET, may cause an alteration of the molecular weight distribution of the original PET.

Chromatography, Gel↗