Search results for " Polyethylene"
showing 10 items of 229 documents
Morphology and mechanical properties of extruded ribbons of LDPE/PA6 blends compatibilized with an ethylene-acrylic acid copolymer
2003
Two grades of low density polyethylene (LDPE) were blended with polyamide-6 (PA) in the 75/25 and 25/75 wt/wt ratios and shaped into ribbons with a Brabender single screw extruder. An ethylene-acrylic acid copolymer (EAA) was used in the 2 phr concentration as a compatibilizer precursor (CP). The morphology of the ribbons and its evolution during high temperature annealing were investigated by scanning electron microscopy (SEM). The results confirmed that EAA does actually behave as a reactive compatibilizer for the LDPE/PA blends. In fact, in the presence of EAA, the interfacial adhesion is improved, the dispersion of the minor phase particles is enhanced and their tendency toward fibrilla…
Photo-oxidation behaviour of polyethylene/polyamide 6 blends filled with organomodified clay: Improvement of the photo-resistance through morphology …
2010
Abstract The impact of small amounts of organomodified clay (OMMT) on the photo-degradation behaviour of two blends obtained by mixing either low-density polyethylene (LDPE) or high density polyethylene (HDPE) with polyamide 6 (PA6) (LDPE/PA6 and HDPE/PA6 75/25 wt-%) was studied. The complex photo-degradation behaviour was followed by monitoring the main physical–mechanical properties of the blends. In particular, mechanical and spectroscopic tests were performed in conditions of accelerated artificial aging. An accurate mechanical and morphological characterization was previously carried out. The presence of the OMMT promotes the unexpected formation of a co-continuous morphology for the H…
Low-density polyethylene/polyamide/clay blend nanocomposites: Effect of morphology of clay on their photooxidation resistance
2017
The photooxidation behaviour of low-density polyethylene (LDPE)/polyamide (PA) blends, containing polyamide 11 (PA11) or polyamide 6 (PA6), has been investigated in the absence and presence of a small amount of commercial organomodified clay (OMMT). The polymer blends LDPE/PA11 and LDPE/PA6 at 75/25 wt./wt.%, with and without OMMT, have been prepared by a two-step procedure: extrusion and sheet formulation. The formulated complex systems have been subjected to accurate morphological analysis in order to evaluate the effect of the OMMT presence on the refinement of the blend morphology. Furthermore, the produced sheets have been subjected to arterial UVB exposure and the variations of the me…
Intercalation effects in LDPE/o-Montmorillonites nanocomposites
2007
Abstract Typical montmorillonite clays (Cloisite ® Na + , Cloisite ® 30B) were modified by treatment with octadecyl ammonium chloride (ODC) and successive additions of octadecylamine (ODA). XRD analyses of the modified clays indicated an increase of the basal spacing of the (0 0 1) planes depending on the ODC or ODA additions. Nanocomposites were prepared by dispersing the modified clays (3% w/w concentration) in LDPE, using a Brabender mixer. XRD measurements of the obtained products indicated in some cases the achievement of intercalation effects, which were confirmed by TEM analysis. Some thermal, mechanical, dynamic-mechanical and rheological properties were evaluated and correlated to …
An a priori prediction model of response to peginterferon plus ribavirin dual therapy in naïve patients with genotype 1 chronic hepatitis C.
2014
none 29 no Background: Aim was to select naïve patients with genotype 1 chronic hepatitis C having a high probability of response to Peg-interferon. +. ribavirin therapy. Methods: In 1073 patients (derivation cohort), predictors of rapid and sustained virological response were identified by logistic analysis; regression coefficients were used to generate prediction models for sustained virological response. Probabilities at baseline and treatment week 4 were utilized to develop a decision rule to select patients with high likelihood of response. The model was then validated in 423 patients (validation cohort). Results: In the derivation cohort, 257 achieved rapid virological response and 8…
Carboplatin and pegylated liposomal doxorubicin for advanced ovarian cancer. Preliminary activity results of the MITO-2 phase III trial
2008
<i>Background:</i> Based on the efficacy of pegylated liposomal doxorubicin (PLD) in relapsed ovarian cancer, we are conducting a phase III study comparing carboplatin plus either paclitaxel or PLD as first-line therapy in advanced ovarian cancer. Because of limited phase I and II data on PLD plus carboplatin in this setting, we conducted an interim activity analysis. <i>Patients and Methods:</i> Patients with stage 1c-IV epithelial ovarian cancer were randomized to carboplatin AUC 5 plus either paclitaxel 175 mg/m<sup>2</sup> or PLD 30 mg/m<sup>2</sup> every 3 weeks for 6 cycles. The interim activity analysis was planned according to a single…
Triple therapy with first-generation Protease Inhibitors for patients with genotype 1 chronic hepatitis C: Recommendations of the Italian Association…
2013
AbstractThe first-generation Protease Inhibitors Boceprevir and Telaprevir administered in triple therapy regimens with Peg-interferon alpha and Ribavirin have been proven effective in increasing the rate of Sustained Virological Response in both naive and treatment-experienced patients with chronic genotype-1 hepatitis C. However, at the individual level, the therapeutic advantage of triple therapy is highly variable and results from the combination of multiple factors related to the characteristics of patient, viral status and liver disease.The recommendations presented are promoted by the Italian Association for the Study of the Liver, with the aim to help the physician in the decision-m…
One-step reactive processing of low density polyethylene and octavinyl polyhedral oligomeric silsesquioxane
2015
Polyhedral oligomeric silsesquioxane (POSS) are an innovative class of organosilicon compounds suitable for formulation of advanced organic-inorganic hybrid materials. Nanocomposites based POSS found application mostly in high-temperature resistance and fire-resistance materials. POSS are characterized by a three dimensional cage-like structure, made of Si-O bonds, with different organic groups directly linked to the Si atoms of the cage structure. The organic groups can be designed to facilitate the dispersion of the nanoparticle itself in the polymer matrix or also to react with the polymer chain. This work focuses on the possibility to obtain crosslinking of polyethylene using octavinyl-…
Oxygen permeability of hydrogel contact lenses with organosilicon moieties
2002
Oxygen transport through two extended wear (day and night) hydrogel contact lenses that contain organosilicon moieties (balafilcon A and lotrafilcon A) was studied in the hydrate (hydrogel) and dry (xerogel) states. The water uptake increased the oxygen permeability [(Dk)app] and transmissibility [Dk/L(av)] coefficients of the dry materials by about 70%. The (Dk)app for the hydrated lenses was determined following the so-called stack procedure. The values obtained were 107 +/- 4 barrer for balafilcon A and 141 +/- 5 barrer for lotrafilcon A, about 5-10 times larger than those previously reported for conventional (without organosilicon moieties) extended wear hydrogels contact lenses. The Dk…
Stabilisation of LDPE cross-linked in the presence of peroxidesII. FTIR study of chemical changes taking place in the LDPE–dicumyl peroxide–Irganox 1…
2000
Abstract The chemical changes taking place in the systems: LDPE–Irganox 1081, LDPE–dicumyl peroxide and LDPE–Irganox 1081–dicumyl peroxide, after homogenisation (in a rolling mill at 130°C) and after homogenisation and cross-linking (at 180°C and 5.0 MPa for 20 min) were investigated by FTIR. It was found that the OH groups in Irganox 1081 were in a bound form, and were most probably linked to the sulphur co-ordination centre. Further, the presence of dicumyl peroxide without Irganox 1081 in LDPE resulted in the formation of hydroperoxide groups at a temperature of 130°C, which were replaced by free hydroxy and carbonyl groups of a ketonic type after cross-linking. Simultaneous addition of …