Добірка наукової літератури з теми "Polypropylene expansé"

The influence of additives of nanofillers containing nanoparticles of copper oxides stabilized by a polymer matrix of maleinized high-pressure polyethylene obtained by the mechano-chemical method on the structure and properties features of metal-containing nanocomposites based on isotactic polypropylene and butadiene-nitrile rubber by x-ray phase and differential thermal analyses is studied. The improvement of strength, deformation and rheological parameters, as well as thermal-oxidative stability of the obtained nanocomposites was revealed, that is probably due to the synergistic effect of interaction of copper-containing nanoparticles with maleic groups of maleinated high-pressure polyethylene. It is shown that nanocomposites based on isotactic polypropylene and butadiene-nitrile rubber can be processed both by pressing method and by injection molding and extrusion methods that expands the scope of its application

A novel polypropylene hollow fiber membrane with a new function of selective adsorption of mercury ions in aqueous solutions was successfully prepared. The surface of the polypropylene hollow fiber membrane was initially modified with polydopamine by surface polymerization, and subsequently grafted with polyacrylamide (PAM) polymer brush via the surface initiated atom transfer radical polymerization (SI-ATRP) technique (thereafter named as PP-PAM). This study investigated the adsorption performance of Hg(II) ions by PP-PAM and the effect of various influencing factors on Hg(II) ion adsorption. The experiment indicated that the Hg(II) adsorption capacity of the PP-PAM increased with the increase of the pH, and the Hg(II) adsorption kinetics was consistent with the pseudo-second-order kinetic model. The adsorption isotherm followed the Langmuir model, with the maximum adsorption capacity calculated to be 0.854 mmol/g for Hg(II) ions. The adsorption study in multi-component system indicated that PP-PAM preferentially adsorbs Hg(II) over Pb(II) ions, with significant adsorption capacity difference of the two heavy metal ions. This study provided an efficient method for the preparation of the adsorptive polypropylene hollow fiber membrane, which expands its application for the selective removal of heavy metal ions.

Composite gypsum binders harden quickly, gain strength quickly and have positive environmental properties. Moreover, they are characterized by increased moisture resistance, which significantly expands the field of application of such gypsum materials. Dispersed reinforcement of composite gypsum binders with polypropylene fibers makes it possible to obtain composites characterized by high performance properties. On basis of developed compositions of gypsum-cement-pozzolanic and composite gypsum binders with polymer fibers, gypsum composites have been created, characterized by increased strength, water resistance, frost and corrosion resistance.

AbstractPolypropylene composites filled with inorganic fillers are widely used due to their good mechanical and thermal properties. The modification efficiency of filler incorporated into thermoplastic polymer strongly depends on its shape and dimension. Therefore, the development of novel hybrid composites modified with particle and fibrous shaped fillers expands the range of thermoplastic composite applications. This work investigates the influence of glass fiber and basalt powder and their shape on the mechanical properties of polypropylene-based composites. Mechanical properties of hybrid composites were evaluated using static tensile test, impact resistance, and hardness measurements. The thermomechanical stability of the materials was evaluated via dynamic mechanical thermal analysis. Results indicated that the incorporation of inorganic fillers significantly improved the composite sample stiffness at a wide range of temperatures. The research was complemented with structure investigations realized using scanning electron microscopy. Moreover, the incorporation of basalt powder, which is well known for its low friction coefficient, improved the processing properties, as proven by the melt flow index test.

The effect of additives of nanofillers (NF) containing nanoparticles (NP) of copper oxide, stabilized by a polymer matrix of maleized polyethylene (MPE), obtained by the mechanochemical method, on the properties of composites based on isotactic polypropylene (PP) and high-pressure polyethylene (PE) was studied by X-ray phase (XRD) and thermogravimetric (TGA) analyzes. The enhancement of strength, deformation, and rheological parameters, as well as the thermo-oxidative stability of the obtained nanocomposites was revealed, which, apparently, is due to the synergistic effect of the interaction of copper-containing nanoparticles with anhydride groups of MPE. It is shown that nanocomposites based on PP/PE/NF can be processed both by pressing and injection molding and extrusion, which expands the scope of its application.

The effect of nanofiller (NF) additives containing zink oxide nanoparticles stabilized by a polymer matrix of high pressure polyethylene obtained by the mechanochemical method on the structure and properties of metal-containing nanocomposites based on isotactic polypropylene (PP) and high pressure polyethylene (PE) using differential thermal (DTA) and X-ray phase (XRF) analyzes. The improvement of strength, deformation and rheological parameters, as well as thermal-oxidative stability of the obtained nanocomposites was revealed, which, apparently, is associated with the synergistic effect of interfacial interaction of zink — containing nanoparticles in the PE matrix with the components of the PP/PE polymer composition. It is shown that nanocomposites based on PP/PE/NF can be processed both by pressing method and by injection molding and extrusion methods, which expands the scope of its application.

The effect of nanofiller (NF) additives containing nickel oxide nanoparticles stabilized by a polymer matrix of high pressure polyethylene (PE) obtained by the mechanochemical method on the structure and properties of metal-containing nanocomposites based on isotactic polypropylene (PP) and high pressure polyethylene(PE) using differential thermal (DTA) and X-ray phase (XRF) and SEM analyzes. The improvement of strength, deformation and rheological parameters, as well as thermal-oxidative stability of the obtained nanocomposites was revealed, which, apparently, is associated with the synergistic effect of interfacial interaction of nickel-containing nanoparticles in the PE matrix with the components of the PP/PE polymer composition. It is shown that nanocomposites based on PP/PE/NF can be processed both by pressing method and by injection molding and extrusion methods, which expands the scope of its application.

The influence of additives of nanofillers (NF) containing nanoparticles of copper oxides stabilized by a polymer matrix of high-pressure polyethylene (PE) obtained by the mechanochemical method on the structure and properties features of metal-containing nanocomposites based on isotactic polypropylene (PP) and butadiene-nitrile rubber (BNK) is studied by X-ray phase (XRD) and differential thermal analyses(DTA). The improvement of strength, deformation and rheological parameters, as well as thermal-oxidative stability of the obtained nanocomposites was revealed, which, apparently, is associated with the synergistic effect of interfacial interaction of copper-containing nanoparticles in the PE matrix with the components of the PP/BNK polymer composition. It is shown that nanocomposites based on PP/BNK/NF can be processed both by pressing method and by injection molding and extrusion methods, which expands the scope of its application.

This study was undertaken to determine the effectiveness of modified atmospheres and packaging materials on the growth of Penicillium expansum and patulin production in apples. Granny Smith apples were surface sterilized with 76% ethanol and inoculated with 0.1 ml of a 1.1 × 107 spore/ml P. expansum spore suspension. The apples were packaged either in polyethylene (PE) or polypropylene (PP) and treated with three different gas combinations, viz., 58% CO2/42% N2, 48% CO2/52% N2, and 88% CO2/12% N2, and were then incubated for 14 days at 25°C. Fungal growth was monitored every 2 to 4 days by measuring radial growth from the point of inoculation. After the 14th day, apples were pulped, and patulin was extracted, purified, and quantified by high-performance liquid chromatography. PP did not inhibit fungal growth in any of the atmospheres tested, and it only inhibited patulin production in atmospheric gas and 58% CO2/42% N2. PE was very effective and inhibited fungal growth by four- or fivefold, depending on the modified atmosphere. Patulin production in PE-packaged apples was almost completely inhibited by all three gas combinations. Gas chromatographic analysis of the PE-packaged samples before and after the incubation period showed that CO2 levels dropped and N2 levels increased for all of the atmospheres tested. Our studies showed conclusively that PE is an excellent packaging material for the storage of apples since it inhibited the growth of P. expansum, thereby allowing <3.2 μg/ml of patulin to be produced, regardless of gaseous environment.

The paper presents a method for rapid multi-omics investigation of biological samples using polypropylene bulk porous samplers. The use of porous samplers makes it easy to collect samples from the surface of the skin, mucous membranes, and biological fluids even in a field, and the surfaces of wounds and injuries. Collected samples do not require special storage conditions, and the samplers are lightweight and very compact. They can be used to monitor the condition of cosmonauts before, during, and after the spaceflight with the same sample collection method. The analysis of biomaterial applied to the sampler is performed using direct mass spectrometry methods, similar to the dried blood spot technique that is already used in clinical practice. However, bulk porous samplers allow expanding the range of analytes ionization conditions, which increases the stability and reliability of the ionization process, which expands the variety of analyzed molecules. The proposed method can be used to study compounds of various classes, including proteins, lipids, and metabolites, to systematically monitor the status of people in extreme conditions (athletes, astronauts), or to study the condition of patients in the clinic.

Aujourd'hui, le secteur des transports est en pleine mutation avec la transition des véhicules thermiques vers les véhicules électriques. Par conséquent, les matériaux largement utilisés dans les véhicules, tels que le PPE, doivent également évoluer en raison d'exigences plus strictes en matière de propriétés ignifuges.Dans cette thèse, trois approches ont été envisagées pour améliorer les propriétés ignifuges du PPE et atteindre une classification V0 lors du test vertical UL-94, selon les trois différentes étapes de fabrication du PPE. Ces étapes sont : (1) le mélange du polypropylène (PP) avec divers additifs par un processus d'extrusion, (2) l'expansion du PP formulé, et (3) le moulage des billes de PPE dans la forme désirée. Avant d'étudier les différentes approches d'ignifugation de l'EPP, le test feu vertical UL-94 a été instrumenté afin d'en obtenir plus d'informations et de mieux comprendre les propriétés feux des différents matériaux. Les différentes approches envisagées ont été les suivantes : (1) l'incorporation de retardateurs de flamme (RF) et d'agents de synergie dans la matrice de PP avant l'expansion, il s'agit de l'approche la plus courante. Dans cette approche, la comparaison entre différent RF ayant des modes d'action différents (RF intumescent, générateur de radicaux libres, etc.) a été plus particulièrement étudiées. Une optimisation de la combinaison des RF et une étude de l'influence du mode de fabrication (étape d'expansion) ont été nécessaire. En effet, en raison de la grande quantité nécessaire et de leur potentiel rôle d'agents de nucléation, les RF peuvent perturber l'expansion du PP. Le mécanisme d'action des RF choisis a été étudié avant et après l'étape d'expansion. Il s'avère que l'étape d'expansion est une étape très complexe pour la conservation des propriétés feu qui a induit l'étude d'approches alternatives pour la validation de concept différents. L'alternative (2) concerne l'application d'un revêtement ignifuge sur les billes de PPE (avant le moulage) et la (3), l'application d'un revêtement ignifuge sur la pièce finale moulée (barreaux de PPE). Cependant, ces approches présentent également certains inconvénients. En effet, le PPE présente de faibles propriétés adhésions car il ne possède pas de groupes fonctionnels. Ainsi, une optimisation par traitement plasma est nécessaire pour augmenter l'adhésion du PPE. Plusieurs revêtements ignifuges ont été appliqués en surface et le moulage des billes de PPE revêtues a été étudiée. Les propriétés ignifuges des billes de PPE moulées revêtues et des barreaux de PPE revêtues ont été étudiées en utilisant le test vertical UL-94
Today the sector of transport is changing with the transition from thermal vehicles to electrical vehicles. Thus, the materials widely used in vehicles as EPP also have to change due to higher requirements in terms of fire properties.In this thesis, three approaches were considered to increase the fire properties of EPP and reach a V0 rating at UL-94 vertical test, according to the three steps of manufacturing EPP. In fact, to manufacture EPP, three steps are necessary: (1) the polypropylene (PP) is melt blended with various additives via an extrusion process, (2) the blended PP is expanded, i.e. an expansion gas is introduced into it to form EPP beads and (3) the EPP beads are then molded into the desired shape. Before investigating the different approaches, the UL-94 vertical test was instrumented in order to obtain more information and have a better understanding in terms of fire properties. The different approaches considered were: (1) incorporating flame retardants and synergists into the PP matrix before expansion, this is the most common approach. This approach was deeply investigated with a comparison between several FRs with different modes of action (intumescent FR, free radical generator, etc), an optimization of the most efficient FRs combination and a study of the influence of industrial manufacturing, especially the expansion step. Indeed, the FRs can disrupt the foaming processability (expansion step), due to the high amount of FRs needed and the fact that FRs can play the role of nucleating agents. Moreover, the mechanism of action of the chosen FRs was studied before and after the expansion step. To counter the complexity of the expansion step in the approach (1), alternative approaches were studied in order to validate others concept. The alternative (2), applying a flame-retardant coating on the EPP beads (before molding) and (3) applying a flame-retardant coating to the molded final piece (EPP bars). However, these approaches have also some drawbacks. Indeed, the EPP has poor adhesion properties because it has no functional groups. Thus, an optimization of a plasma treatment was needed in order to increase the adhesion of EPP. Several flame retardant coatings were applied on the surface and the moldability of the coated EPP beads was studied. Finally, the fire properties at UL-94 vertical test of the molded coated EPP beads and coated EPP bars were studied

Expansive soils are those whose volume changes take place while it comes in contact with water. It expands during rainy season due to intake of water and shrinks during summer season. Expansive soils owe their characteristics due to the presence of swelling clay minerals. Expansive soils cover nearly 20% of landmass in India and include almost the entire Deccan plateau, western Madhya Pradesh, parts of Gujarat, Uttar Pradesh, Andhra Pradesh, Karnataka and Maharashtra. The properties that describe the expansive behaviour of soils are free swell index, swell potential and swell pressure. This behaviour has an impounding effect on the bearing capacity and strength of foundation lying on such a soil. Some of the stabilization techniques which are currently being used are physical alternations, sand cushioning, belled piers, under reamed piers, granular pile anchors, chemical stabilization, and fibre reinforcement techniques. This paper focuses on improvement in the strength characteristics of stabilized Chittur soil. The commonly used stabilizer for expansive soils is lime. This paper looks upon alternative materials such as fly ash and polypropylene fibres in order to reduce the lime content. It was concluded from the trials that an optimum combination of 1.5% lime, 10% fly ash and 0.2% polypropylene fibres contribut