Search results for "Low-density polyethylene"

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 …

“Compatibilization” through Elongational Flow Processing of LDPE/PA6 Blends

2018

Polyamide/polyolefin blends have gained attention from the academia and the industry for several years. However, in order to optimize their properties, some drawbacks such as chemical incompatibility must be adequately overcome. This can be done by adding suitable compatibilizers. On the other hand, it is less known that suitable processing techniques may also lead to significant results. In a previous work on a low-density polyethylene/polyamide 6 (LDPE/PA6) blend, we found that the orientation due to elongational flow processing conditions could lead to an unexpected brittle&ndash

Modified arabinoxylan-based films. Part B. Grafting of omega-3 fatty acids by oxygen plasma and electron beam irradiation.

2003

Arabinoxylans (AXs) are byproducts of the cereal milling industry. To obtain high-value products, AXs have been used as a film-forming agent. Hence, AX-based films are poor water vapor barriers. The objectives of this study were to graft omega-3 (omega3) fatty acids onto AX polymeric chains by using two new technologies: cold plasma and electron beam (EB) irradiation. Results show that the surface hydrophobicity of the modified films is higher than that of a waxy coating or a low-density polyethylene (LDPE) film. In addition, FTIR spectroscopy analysis reveals vibration bands attributed to new chemical functions. Finally, a decrease in water vapor permeability (WVP) is obtained for the film…

A quantitative electron-microscopic study of a linear polyethylene fraction crystallized at different temperatures

1981

Replica and thin-section electron microscopy was performed on a linear polyethylene fraction (Mw = 1.89 × 105, Mn = 1.79 × 10 5) which was either isothermally crystallized or quenched at difference temperatures. The results are numerically analyzed in such a manner so as to give the distribution of the total long spacing and of the crystallite and amorphous thicknesses. The quantitative information about the maximum and minimum values for these parameters at each crystallization temperature yields important clues as to possible molecular processes involved. Qualitative information regarding general morphology, molecular tilt with respect to the lamellar surface, and possible crystallographi…

A quantitative electron microscopic study of the crystallite structure of molecular weight fractions of linear polyethylene

1984

Utilizing thin-section techniques, transmission electron microscope studies were performed on a series of bulk-crystalized fractions of linear polyethylene covering the range M = 5 × 103−6 × 106. The crystallization conditions were varied from long-time isothermal to rapid quenching. Quantitative analysis could be carried out on such samples crystallized under controlled conditions. The crystallite thickness distributions and long periods are presented in terms of histograms. From these data the degree of crystallinity can be calculated and was found to compare favorably with that from other methods. The amorphous thickness increases significantly with molecular weight for all modes of crys…

Shear characterization of CaCO3-filled linear low density polyethylene

1988

Shear properties of CaCO3-filled linear low density polyethylene have been determined over a wide range of filler loading. The viscosity rises with the filler loading especially at low shear rates and a yield value appears for CaCO3-contents larger than 5%. The decrease of the die-swell ratios of the filled samples indicates a reduction of the melt elasticity.

Laboratory and in-situ tests for estimating improvements in asphalt concrete with the addition of an LDPE and EVA polymeric compound

2019

Abstract Pavement deformation is a critical issue in the design of pavement structures and the related mixture. Asphalt concretes may be very sensitive to this problem, in compliance with the viscoelastic behaviour of the adopted bitumen. To improve the material performance, many attempts have been made to introduce in the mixture other materials as “modifiers” or “additives” for increasing the permanent deformation resistance and the elastic modulus of the material. Among the different possible materials, polymers determined significant improvements in the road pavement performance. In this paper, the authors tested the adoption of a specifically engineered polymeric compound, in order to …