The nuisance due to the noise of automobile traffic: An investigation in the neighborhoods of freeways

An inquiry was held among 400 people living near freeways in an attempt to determine the characteristics of traffic noise nuisance. A nuisance index was compiled, based on the answers to a questionnaire. Nuisance expressed in these terms was then compared with the noise level measured on the most exposed side of each building. Correlation between the nuisance indexes and the average noise levels is quite good for dwellings with facades parallel to the freeway. At equal noise levels on the most exposed side, the nuisance given for these latter dwellings is lower than for others

Matrix-filler interactions in a co-ground ecocomposite: surface properties and behaviour in water

Ecocomposites made up of polystyrene and starch were produced by co-grinding. The mechanism by which the composite is formed was identified by following the particle size and morphology. The size reduction of the matrix particles is favoured by the presence of starch which adheres on polystyrene surface, playing the role of agglomeration inhibitor between matrix particles. Thus, the filler is well dispersed in the matrix, permitting a good homogeneity of the composite properties. The hydrophilic behaviour of starch is reduced by co-grinding, resulting of a decrease of the acid and non dispersive components of the surface energies. Consequently the interactions between the initially hydrophobic matrix and hydrophilic filler are enhanced without using a compatibilizer. Thus, the water-resistance of the co-ground composite materials is better compared to blends since blends pellets introduced in water are rapidly disintegrated while an adapted co-grinding time permits to avoid this problem. It was seen that the diffusion coefficient of water in the composite pellets decreases with an increase of the co-grinding time for the lower filler rates, while it is the opposite for high filler rates. Moreover, the diffusion coefficient increases with the filler ratio

Polyimide (PI) films by chemical vapor deposition (CVD): Novel design, experiments and characterization

Polyimide (PI) has been deposited by chemical vapor deposition (CVD) under vacuum over the past 20 years. In the early nineties, studies, experiences and characterization were mostly studied as depositions from the co-evaporation of the dianhydride and diamine monomers. Later on, several studies about its different applications due to its interesting mechanical and electrical properties enhanced its development. Nowadays, not many researches around PI deposition are being carried. This paper presents a PI film deposition research project with an original CVD process design. The deposition is performed under ambient conditions (atmospheric pressure) through a gas flux vector. Design of apparatus, deposition conditions and preliminary characterizations (IR, SEM and surface analyses) are discussed

Effect of the plasticizer on permeability, mechanical resistance and thermal behaviour of composite coating films

Thin layer deposit of a composite material on solid particle surfaces used in the food industry aims to ensure the protection of food powder against aggressive environments such as amoist atmosphere. The layer, having a thickness of a few fractions of millimetre, must have certain physico-chemical properties: it must be compatible with the product, itmust be impermeable to water and oxygen, itmust have goodmechanical strength and good adhesion to the surface of the coated powder. Furthermore the layer must fulfil the regulatory requirements for food ingredients. Film properties like continuity, permeability, and mechanical resistance depend on the choice of the excipients included in the formulation and the operating conditions which can modify the constraints generated at the interface film-powder. As a consequence, the scientific issue consists of combining the local phenomena happening at amicroscopic level on the surface of the particle with the processing technology and the process parameters. In a first step, the attention is focussed on the film and its formulation. For this step, films are prepared separately and they are dried under very smooth conditions. Test samples are taken from the formed composite films and contain hydroxypropyl methylcellulose asmatrix (67% of driedmaterial),micronised stearic acid as hydrophobic filler (20% of driedmaterial) and a plasticizer (13% of driedmaterial). The filmformation procedure and the testmethod are described in detail. The effect of the type of plasticizer (different grades of PEG) onmechanical, thermal and permeability properties of the coating film is studied. The results show that PEG with higher molecular rate provides a better plasticizing effect for the film but increases the water vapour permeability of the film

How to combine a hydrophobic matrix and a hydrophilic filler without adding a compatibilizer – Co-grinding enhances use properties of renewable PLA-starch composites

In order to avoid the use of compatibilizers or plasticizers, co-grinding was performed to produce PLA – starch composite materials. Fragmentation and agglomeration phenomena were analysed to propose a production mechanism. Co-grinding enhances dispersion of the filler in the matrix and interactions between the materials. Consequently while blending the two materials has a negative effect on mechanical properties, co-grinding permits to improve them if optimized operating conditions are applied. Water uptake and diffusion are also controlled by co-grinding conditions. This treatment allows the production of composite materials offering good use properties without any use of a compatibilizer or a plasticizer

Corrosion protection of AA2024 sealed anodic layers using the hydrophobic properties of carboxylic acids

The present study investigates the use of carboxylic acids as a post-treatment for sealed AA2024 anodised in tartaric–sulphuric acid electrolyte. Four monocarboxylic acids with different carbon chain lengths were tested ((CH3–(CH2)n–COOH with n=4, 8, 12 and 16). Hydrophobic surface properties after the posttreatment were characterized by contact angle measurements. Electrochemical impedance spectroscopy (EIS) was performed to assess the ability of the four carboxylic acids to form protective films. It was shown that stearic acid (n=16) used in its pure molten state was the most efficient. The organic film formed very rapidly (under 5 min) and contributed to the enhancement of the protection in terms of corrosion resistance of the sealed anodic layers. EIS measurements showed the presence of the organic films on the specimen surface

Solving Geometric Constraints by Homotopy

International audienceNumerous methods have been proposed in order to solve geometric constraints, all of them having their own advantages and drawbacks. In this article, we propose an enhancement of the classical numerical methods, which are, up to now the only ones that apply to the general case

Production, by co-grinding in a media mill, of porous biodegradable polylactic acid-apatite composite materials for bone tissue engineering

This paper presents the results of a study of the production of porous biodegradable composite materials by co-grinding, followed by scaffolding. Dry powders of polylactic acid and nanocrystalline carbonated apatite, analogous to bone mineral were co-ground in a tumbling ball mill in order to disperse the mineral filler within the polymer. Porous scaffolds were then made by hot moulding the mixture of the two components along with a pore-forming agent which was subsequently eliminated by washing. The mechanical resistance of the scaffolds was evaluated in order to determine the best operating conditions to produce implants offering optimised properties for use as bone substitutes. It was shown that 30 wt.% of filler and 70 wt.% of pore-forming agent produce scaffolds which are sufficiently porous and resistan