Search results for "density polyethylene"

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 …

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…

Recycling of plastics from packaging

1997

Plastic waste coming from the separate collection of packaging film was recycled and characterized. The material is a blend of low density and linear low density polyethylene and after recycling shows mechanical and rheological properties depending on the processing conditions and apparatus. High processing temperature and high residence times strongly enhance the degradation processes and reduce the mechanical properties, in particular the elongation at break. A possible use of this recycled plastic is for the production of low pressure pipes but the properties are lower than those of virgin pipe grade polyethylene. By introducing additives, like antioxidants, inert fillers and impact modi…

Experimental Investigation for Local Tank Inflow Model

2014

In the present paper the effect of private roof tanks and of the float valve characteristics on apparent losses due to water meter errors was investigated via an experimental study. The tests were carried out at the Environmental Hydraulic Laboratory of the University of Enna (Italy), on a high-density polyethylene (HDPE 100 PN16) looped distribution network. The experimental results showed that network pressure plays an important role in the characterisation of the floating ball valve emitter law, but the tank operating condition is the most relevant aspect to be considered mainly for water meter error evaluation. (C) 2014 The Authors. Published by Elsevier Ltd.

Small-angle x-ray scattering experiments for investigating the validity of the two-phase model

1973

A New method for evaluating SAXS curves of polymer samples with lamellar structure is applied to two typical scattering curves measured with a solution-crystallized linear polyethylene and a melt-crystallized branched polyethylene respectively. The method permits a rigorous check of the validity of the two-phase model and yields, without additional measurement, the volume fractions of the two phases and the difference in their densities. The densities can than be obtained by measuring the overall density of the sample. The results are: ρc = 0.996 g/cm3,ρa = 0.854 g/cm3, wa = 0.20 for the solution-crystallized sample; ρc = 0.967 g/cm3,ρa = 0.850 g/cm3, wa = 0.36 for the melt-crystallized sam…

The antioxidant effect in controlling thermal degradation of a LDPE blow film

2004

It is well known that antioxidants are widely used to prevent thermal degradation of high density and linear low density polyethylene. Antioxidants are not always present in low density polyethylene and only small amounts are usually added to these resins. In this work the effect of an antioxidant system on a low density resin having MFI (190 °C/2.16 kg)=2 g/10′ and density 0.9230 g/cm3 has been studied. Its effect on melt viscosity has been studied by means of a batch mixer and the torque vs time behaviour has been analysed. The results show that a maximum in the torque vs time curve can be seen for the material containing antioxidant. In contrast, the material without antioxidant does not…

The rheological behaviour of HDPE/LDPE blends. II. Die swell and normal stresses

1984

Die swell data are presented for different high-density/low-density polyethylene blends. The data relating to samples with frozen-in stresses are represented, collected as a function of the usual operational parameters (L/D ratio, flow rate, temperature). Data obtained with annealed samples are used to derive, through a theoretical approach, normal stresses. Die Strahlaufweitung wurde fur verschiedene Mischungen aus Polyethylenen hoher und niedriger Dichte gemessen. Die an Proben mit eingefrorenen Spannungen erhaltenen Werte wurden in Abhangigkeit von technologischen Parametern (Lange/Durchmesser-Verhaltnis, Fliesgeschwindigkeit, Temperatur) dargestellt. An getemperten Proben gemessene Wert…

Mechanical properties of blends of low density polyethylene with isotactic polypropylene II. effect of mixing temperature and rate

1989

Abstract The effects of mixing temperature and rate on tensile properties of some blends of low density polyethylene with isotactic polypropylene have been studied. Results, with those presented previously on the effect of mixing time, indicate significant effects of mixing parameters and suggest the need to find an “optimum mixing procedure” for each kind of blend.

The rheological behaviour of HDPE/LDPE blends

1983

The rheological behaviour of three types of HDPE/LDPE blends at several compositions (various weight percentages of LDPE) has been studied with the aid of a capillary rheometer and three different capillaries.

1997

Polyethylene wastes (low-density polyethylene, high-density polyethylene and their binary blends) were subjected to high-energy radiation, using a 60Co gamma radiation source. The crosslinked materials thus obtained were processed to heatshrinkable films. Tensile strength could be sharply improved by increasing the dose up to 20 Mrad, simultaneously increasing the elongation at break of the most degraded PE waste. An increase of the degree of compatibility of LDPE and HDPE waste was also observed. All samples examined exhibit a “memory effect” after drawing at 130°C and cooling under tension followed by further heating under relaxed conditions. The value of shrinkage depended on the degree …