Ali Benhassaine

Fire resistance and mechanical properties of a huntite/hydromagnesite/antimony trioxide/decabromodiphenyl oxide filled PP-PE copolymer

A natural mineral filler containing mainly huntite and hydromagnesite together with a blend of antimony trioxide (Sb2O3) and decabromodiphenyl oxide (DBDPO) was used to reduce the flammability of an ethylene-propylene copolymer. At the same time it was desirable to improve the stiffness of the copolymer without damaging its impact resistance even at high filler content. All the components and the resulting composites were studied by differential thermal (DTA) and thermogravimetric analysis (TGA). Specific flammability tests and mechanical tests were also carried out on the composites. The influence of the mineral filler and/or the Sb2O3/DBDPO blend on copolymer properties was investigated. The best results were obtained by combining both of the main components to give 25% mineral filler and 20% Sb2O3/DBDPO blend.

The influence of particle size on the pozzolanic reactivity of quartz powder

Abstract Materials with cement-based matrices represent a class of materials notable for their wide and plentiful use. Up to the present, component reactivity was closely linked to the materials vitreous characteristics. The question we wanted to find an answer to was: is the pozzolanic reaction one which is specific to vitreous materials? To tackle it, we chose quartz, a mineral commonly found in cement-based matrices and supposed to be chemically inert because of its crystalline structure. The pozzolanic reaction of quartz is a complex dissolution–precipitation reaction influenced by numerous parameters. It is only barely perceptible for the particle diameters exceeding a certain critical size.

The Combined Action of Huntite and Hydromagnesite for Reducing Flammability of an Ethylene-Propylene Copolymer

Abstract The flammability of a filled ethylene-propylene copolymer is discussed. A mineral filler with 40% of hydromagnesite and 60% of huntite by weight is used as a flame retardant additive. Some burning characteristics and mechanical properties have been studied in relation to the amount of incorporation. Flammability was measured by the oxygen index method, the dripping test and the rate of spread of flame test. Thermal degradation was investigated by differential scanning calorimetry and thermogravimetry in combination with differential thermal analysis.

Binder granulation and compaction of coloured powders

This paper gives results of a study of compacts made from both a free powder mixture and granules made from this same mixture, and produced by two binder granulation techniques: high shear granulation and fluidised bed granulation. The characteristics of the compacts are analysed in terms of colour and aspect derived from their reflectance spectra and related to the flow properties and bulk density of the components forming the compacts.

Flowability of a mixture of two powders obtained by co-grinding, mixing and surface treatment

Abstract Usage properties of powder mixtures like flowability and floodability depend strongly on their granular characteristics: size, shape, surface and spread of particle size. The products used are mixtures elaborated from two micron sized powders, made of synthetic minerals. Their particle size distributions are each initially mono-modal, respectively 5 μm and 70 μm. The mixture elaboration procedure consists in making several successive combined stages of co-grinding, mixing and surface treatment by addition of surfactants. We obtain thus several mixtures Mi having different rheological behaviours and particle size distributions—ascertained on a electron beam microscope. The results permitted in understanding the influence of the granular macrostructure and the effect of a surface treatment on a powders rheological behaviour.

Pneumatic selection of fly ash: selection methods — influence of the operating parameters

This work concerns the use of a pneumatic classifier in the valorization of fly ash. This classifier is characterized by a rotor positioned vertically. Firstly, a study in laboratory was carried out. Three parameters were retained: the rotation speed of the rotor, the air flow and the ash feeding rate. The main parameter is the rotation speed of the rotor. There is a relation between the cut diameter and the speed rotation: d50=K/V with V as the speed and K as a factor in function of the process. The increase of the air flow and the ash feeding rate favours the extraction of the fine particles. After that, we realized a study of the industrial feasibility of the selection. We observe the same relation as those obtained during the laboratory study. We have found a set of operating parameters so as to obtain four granulometric fractions (<10, <30, <50 and <80 μm).

Granular self-organisation and reactivity - adsorbates and agglomerates particle size influence

Abstract The aim of this work is to study the organisation of the distributed system and the influence of adsorption and agglomeration phenomena in a dry bi-phase mixture. The studied system is a mixture of silica and carbonate. The parameter of interest is particle size. With the crossover of different fractions of silica and carbonate, it is possible to build a dimensional chessboard and then study the role of dimension in the organisation of distributed system. In these mixtures, several combinations are possible following the particle size. These combinations result from agglomeration and adsorption mechanisms. It is necessary to distinguish self-attractive phenomena (self-agglomeration and self-adsorption) that concern particles of same chemical composition, and inter-attractive phenomena (inter-agglomeration and inter-adsorption) that concern particles of different chemical compositions. The reactivity of the different mixtures treated thermally at 850 °C is measured by X-ray diffraction (DRX). It is estimated by the quantity of produced phases. Then this reactivity is explained by the different attractive phenomena studied.

Incorporation d'ophite dans un copolymere éthylene-propylène: Influence sur la coloration et le comportement mecanique des composites

Plastics are generally reinforced and colored by using a combination of a natural filler or glass fiber and a synthetic coloring agent or pigment. Filler loading is usually comprised between 20 and 60%, while that of the coloring agent is often less than 3%. A natural mineral filler, named ophite, was incorporated into a PP-PE copolymer. This naturally colored filler is able to both color the polymer green and to reinforce it. The colorimetric properties obtained (CIELab space) highlights the importance of filler granulometry on the appearance of the filled polymer (tint, saturation, brightness) and the main influence of the submicronic fraction. The results also show the use which can be made of a physical model of diffusion to forecast how the tint of the filled specimens evolves. Moreover, the flexural modulus and the impact resistance obtained are comparable to those of common mineral fillers (talcs, micas, kaolins) in the same polymer matrix.