Search results for " polyethylene"
showing 10 items of 229 documents
Effects of confinement on insulin amyloid fibrils formation.
2006
Insulin, a 51-residue protein universally used in diabetes treatment, is known to produce amyloid fibrils at high temperature and acidic conditions. As for other amyloidogenic proteins, the mechanisms leading to nucleation and growth of insulin fibrils are still poorly understood. We here report a study of the fibrillation process for insulin confined in a suitable polymeric hydrogel, with the aim of ascertain the effects of a reduced protein mobility on the various phases of the process. The results indicate that, with respect to standard aqueous solutions, the fibrillation process is considerably slowed down at moderately high concentrations and entirely suppressed at low concentration. M…
Using organoclay to promote morphology refinement and co-continuity in high-density polyethylene/polyamide 6 blends – Effect of filler content and po…
2010
We investigate the gradual changes of the microstructure of two blends of high-density polyethylene (HOPE) and polyamide 6 (PA6) at opposite composition filled with increasing amounts of an organo-modified clay. The filler locates preferentially inside the polyamide phase, bringing about radical alterations in the micron-scale arrangement of the polymer phases. When the host polyamide represents the major constituent, a sudden reduction of the average sizes of the polyethylene droplets was observed upon addition of even low amounts of organoclay. A morphology refinement was also noticed at low filler contents when the particles distributes inside the minor phase. In this case, however, keep…
Material properties of various intraocular lenses in an experimental study.
2002
<i>Introduction:</i> With the recent introduction of small-incision cataract surgery, requirements for intraocular lens (IOL) flexibility, strength and hydrophilicity have rapidly evolved. The IOL surface, however, remains a critical factor influencing uveal biocompatibility. <i>Purpose:</i> To objectively quantify factors of material properties of various IOLs using contact angle measurements, differential scanning calorimetry, dynamic-mechanical measurements and scanning electron microscopy. <i>Material and Methods:</i> In our study, 17 currently available IOLs were investigated using contact angle measurements to assess hydrophilicity and biocompatibil…
Sun radiation and temperature impact at different periods of the year on the photooxidation of polyethylene films
2017
Analysis of the IR spectra of weathered films exposed at different periods of the year reveals that, the main regions of the IR spectrum affected by solar irradiation and temperature variation are the complex carbonyls and unsaturations composite absorption bands. Their respective kinetics vary in different manner according to the period at which the exposure is started. Curve fitting has been performed to refine the analysis of the IR spectra and to identify all the chemical species constituting the complex absorption bands. The analysis of the results let appears that whatever the exposure period of the year is, it does not affect the type of developing products, but it has strong effect …
Analysis of Geometrical Relationships and Friction Losses in Small-Diameter Lay-Flat Polyethylene Pipes
2016
[EN] The use of lay-flat polyethylene pipes to irrigate horticultural crops has been receiving widespread attention in the last decade, due to the significant improvements in their hydraulic performance, their potentially high application efficiency, and their limited installation costs. However, even if hydraulic design procedures for conventional microirrigation systems are fairly well established, there is still the need to know how different pipe-wall thicknesses of lay-flat pipes can affect the pipe geometry under different operating pressures as well as the related consequences on friction losses. This paper, after comparing two different procedures (caliper and photographic) to asses…
POSS Grafting on Polyethylene and Maleic Anhydride-Grafted Polyethylene by One-Step Reactive Melt Mixing
2018
This study reports the one-step reactive melt mixing preparation of organic-inorganic hybrid based on maleic anhydride-grafted polyethylene and 3-(2-aminoethyl)aminopropyl-heptaisobutyl substituted polyhedral oligomeric silsesquioxane, (NPOSS), as well as on low-density polyethylene and allyl-heptaisobutyl-POSS (1POSS) in dicumyl peroxide presence, which is believed to activate the unsaturation of the reactive functional group of POSS itself. The successful grafting of POSS molecules onto polymeric backbones was probed through rheological and spectroscopic analysis. Grafting of POSS molecules enhances their dispersion in the polymeric matrix as shown by morphological analysis. Moreover, the…
Rheological properties of asphalt binder modified with waste polyethylene: An interlaboratory research from the RILEM TC WMR
2022
Funding Information: The RILEM Technical Committee on Valorisation of Waste and Secondary Materials for Roads (TC 279-WMR) and the members of Task Group 1 are gratefully acknowledged. The authors would also like to thank Nynas AB and Swiss company Innorecycling for supporting the interlaboratory activity by providing reference neat binder and PE-pellets, PE-shreds additives. The contribution of the Swiss National Science Foundation ( 205121_178991 ) to the Swiss partners is also acknowledged. Funding Information: The RILEM Technical Committee on Valorisation of Waste and Secondary Materials for Roads (TC 279-WMR) and the members of Task Group 1 are gratefully acknowledged. The authors would…
Impact of Safety-Related Dose Reductions or Discontinuations on Sustained Virologic Response in HCV-Infected Patients: Results from the GUARD-C Cohor…
2015
Background: Despite the introduction of direct-acting antiviral agents for chronic hepatitis C virus (HCV) infection, peginterferon alfa/ribavirin remains relevant in many resource-constrained settings. The non-randomized GUARD-C cohort investigated baseline predictors of safety-related dose reductions or discontinuations (sr-RD) and their impact on sustained virologic response (SVR) in patients receiving peginterferon alfa/ribavirin in routine practice. Methods: A total of 3181 HCV-mono-infected treatment-naive patients were assigned to 24 or 48 weeks of peginterferon alfa/ribavirin by their physician. Patients were categorized by time-to-first sr-RD (Week 4/12). Detailed analyses of the i…
Dielectric Relaxations in Confined Hydrated Myoglobin
2009
In this work we report the results of a broadband dielectric spectroscopy study on the dynamics of a globular protein, myoglobin, in confined geometry, i.e. encapsulated in a porous silica matrix, at low hydration levels, where about only one or two water layers surround the proteins. In order to highlight the specific effect of confinement in the silica host, we compared this system with hydrated myoglobin powders at the same hydration levels. The comparison between the data relative to the two different systems indicates that geometrical confinement within the silica matrix plays a crucial role in protein-water dielectric relaxations, the effect of sol-gel encapsulation being essentially …
Properties of radiation-modified blends of polyethylene with elastomers and liquid crystalline copolyester
2001
The results are given on the effect of γ-irradiation on properties of blends of high and low-density polyethylene (HDPE, LDPE) with elastomers -ethylene/propylene/diene rubber (EPDM) and chlorinated polyethylene (CPE), and thermotropic liquid crystalline polymer (LCP). The morphological, thermal, mechanical properties (including thermosetting properties) and adhesion properties of blended composites were investigated. A special attention was paid to the applicability of the blends as thermosetting materials (TSM). The LCP used was a copolyester of poly(ethylene terephthalate) with p-(hydroxybenzoic acid) in the ratio 40: 60. It was found that addition of LCP essentially influenced the therm…