Improvement In Various Properties Research Articles

Accelerating carbonation in lime-based mortar in high CO2 environments

To accelerate the carbonation of lime, mortar samples were cured in chambers with high CO2 concentration. Two types of lime mortar were prepared, which are similar to Roman mortar types: lime and standard sand (M1) and extra ceramic dust and fragments (M2). After demolding, half of the samples were placed in the climate chamber where conditions were constant (20 °C, 60%, 1600 ppm) for six months, and the rest were left in laboratory conditions (25 °C, 34%, 703 ppm). The carbonation of the samples was evaluated at 28, 90, 120 and 180 days as well as microstructural, physical, hydric and mechanical properties. CO2 curing had pronounced effects on both types of mortar. M2 mortar samples showed advanced calcite precipitation and early improvement in various properties. At later stages, cracks caused drops in those properties.

Exploring the Influence of Methylene Diphenyl Diisocyanate as a Modifier for Ethylene Vinyl Acetate/Thermoplastic Polyurethane Blends

ABSTRACTEthylene vinyl acetate (EVA)/thermoplastic polyurethane (TPU) blend at various blend ratios has been modified via reactive processing with 4,4′-methylene diphenyl diisocyanate (MDI). Modification of the blends with even small amount of MDI shows significant improvement in physico-mechanical properties for EVA/TPU 50/50 and 30/70 blends, and it is also supported by the superior melt rheological behavior and dramatic improvement in oil resistance property. After the treatment of electron beam (dose range: 50–150 kGy), radiation crosslinked EVA/TPU (30:70) blend reveals further improvement in various properties. This particular material can find potential application as cable sheathing component.

Effect of Natural Fibers Surface Treatment and their Reinforcement in Thermo- Plastic Polymer Composites: A Review

In previous years natural fibers are frequently used to reinforce materials. The biodegradability is the main advantage of natural fibers. The disadvantage of using natural fibers in polymer composite material is their poor adhesion ability with a polymeric matrix which affects the various physical and mechanical properties of the composite material. To overcome this disadvantage, the surface of the natural fibers needs to be modified so that a good fiber-matrix adhesion can be established. The various treatment methods such as physical treatment and chemical treatment methods for the improvement of fiber-matrix adhesion have been discussed in this paper. So the overall objective of this review paper is to highlight the previous and recent studies related to the surface treatment of natural fibers and their reinforcement in thermoplastic polymer matrix composites. The improvement in various properties specifically mechanical properties by reinforcing these fibers into thermoplastic polymer matrix composites has also been reported in this paper. Keywords: Fibers, surface modification, composites, polyethylene, polypropylene & PVC.

Black Cotton Soil Modification by the Application of Waste Materials

The black cotton soil is a type of problematic expansive soil which causes many problems in the construction of structures founded on them. It is having a swelling and impervious nature with poor geotechnical subgrade characteristics. In this research an approach is made towards the way of improvement in the various geotechnical properties of black cotton soil such as index properties, swelling characteristics, consolidation characteristics, hydraulic conductivity characteristics and strength characteristics by blending it with waste materials such as river sand, fly ash and marble dust. Hence, from these approaches, the impacting effect of waste materials on the environment reduced due to optimum utilization of these waste materials in the improvement in various properties of black cotton soil.

Cellulose Acetate Based Nanocomposites for Biomedical Applications: A Review.

The development of polymer nanocomposites by incorporating variable nanofillers has attracted attention of scientists, researchers and industrial sectors due to their dramatic improvement in various properties. Cellulose acetate (CA) based nanocomposites have interesting history in the field of medical applications because CA meets a wide range of biomedical implant properties. Since cellulose acetate is considered as a biodegradable, renewable, non-corrosive, non-toxic and biocompatible material, it raised up the unique advantages over many other materials. This review is designed to provide a broad overview of cellulose acetate nanocomposites in the field of medical applications and medical devices.

UV curing behavior and mechanical properties of unpigmented and pigmented epoxy acrylate/SiO2 nanocomposites

Recently, hybrid organic–inorganic nanocomposite UV-cured coatings have received considerable attention. Their attractiveness is due to improvements in various properties, including resistance to scratch, abrasion, heat, radiation as well as other mechanical and electrical properties, while maintaining their transparency and gloss. In this research, TiO2-pigmented and unpigmented epoxy acrylate/SiO2 nanocomposites were prepared and their curing behavior and mechanical properties were evaluated. For this purpose, photo-DSC and DMA were used. The extent of SiO2 content in samples was chosen in the range of 0–3 h−1. The results showed that the ultimate conversion values increased by 14.1 and 17.6 % when 1- and 3-h−1 silica nanoparticles were added to unpigmented formulation, respectively. On the other hand, the final conversion of TiO2-pigmented formulations increased by 31.7 and 57.1 % using 1- and 3-h−1 silica nanoparticles in the formulations, respectively. These results revealed that the incorporation of silica nanoparticles into pigmented formulations had a more considerable effect comparing to the unpigmented ones. The elastic modulus of unpigmented cured films which had 1- and 3-h−1 silica nanoparticles increased by 21.4 and 23.8 %, respectively, in comparison with the neat sample. The effect of silica nanoparticles on the elastic modulus of pigmented cured films was more considerable, and it increased by 28 and 52 % in comparison with the neat sample when 1- and 3-h−1 silica nanoparticles were incorporated into the formulation. The Tg of nanocomposite samples was found to be higher than that for the neat samples. Once again, it was more significant for the pigmented formulations.

Effects of fiber‐surface treatment on the properties of hybrid composites prepared from oil palm empty fruit bunch fibers, glass fibers, and recycled polypropylene

ABSTRACTIn this article, we report the effects of hybridization and fiber‐surface modification on the properties of hybrid composites prepared from recycled polypropylene (RPP), coupling agents, oil palm empty fruit bunch (EFB), and glass fibers through a twin‐screw extruder and an injection‐molding machine. The surface of the EFB fibers was modified with different concentrations (10–15 wt %) and temperatures (60–90°C) of alkali solutions. The structure and morphology of the fibers were observed with the help of Fourier transform infrared spectroscopy and scanning electron microscopy. Different types of composites were fabricated with untreated, alkali‐treated, and heat‐alkali‐treated fibers. Comparative analysis of the mechanical, structural, morphological, and thermal properties of the composites was carried out to reveal the effects of treatment and hybridization. The analysis results reveal that composites prepared from the alkali‐treated (in the presence of heat) fibers show improved mechanical, thermal, and morphological properties with a remarkably reduced water absorption. Additionally, the crystallinity of RPP also increased with the development of biaxial crystals. The improvement of various properties in relation to the structures and morphologies of the composites is discussed. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43049.

Fabrication of conductive elastic nanocomposites via framing intact interconnected graphene networks

Electrically conductive elastic nanocomposites with well-organized graphene architectures offer significant improvement in various properties. However, achieving desirable graphene architectures in cross-linked rubber is challenging due to high viscosity and cross-linked nature of rubber matrices. Here, three dimensional (3D) interconnected graphene networks in natural rubber (NR) matrix are framed with self-assembly integrating latex compounding technology by employing electrostatic adsorption between poly(diallyldimethylammonium chloride) modified graphene (positively charged) and NR latex particles (negatively charged) as the driving force. The 3D graphene structure endows the resulted nanocomposites with excellent electrical conductivity of 7.31 S/m with a graphene content of 4.16 vol.%, extremely low percolation threshold of 0.21 vol.% and also analogous reinforcement in mechanical properties. The developed strategy will provide a practical approach for developing elastic nanocomposites with multi-functional properties.

Advances in thermoplastic polyurethane composites reinforced with carbon nanotubes and carbon nanofibers: A review

Carbon nanotubes (CNTs) have long been recognized as the stiffest and strongest man-made material known to date. Owing to high electrical conductivity, CNTs have also gained interest in the area of electrical appliances and communication related applications. Moreover, carbon nanofibers (CNFs) depict fine electrical and mechanical profile. Due to their miniscule size, excellent mechanical, electrical, and thermal properties, CNTs can only be beneficial if they are homogeneously dispersed and embedded into light-weight engineering polymer matrices. Adding small amounts of CNTs strongly improve the electrical, thermal, and mechanical properties of the composites. In order to enhance their chemical affinity to polymer matrices, chemically modifying the graphitic sidewalls and tips is necessary. This article reviews the processing technology and improvement of various properties of carbon nanotube-reinforced thermoplastic polyurethane (PU) composites. Initially, the structure, morphology, mechanical, thermal, and electrical properties of nanotubes are described. Then various strategies for fabricating PU/CNTs composites and their properties are discussed. To conclude, recent developments in the field of mechanical, thermal, and electrical properties of thermoplastic PU reinforced with nanotubes and nanofibers are reviewed. A brief account regarding the toxicity and environmental safety aspects of carbon nanomaterials is also included in this article.

Improvement in tensile properties of PVC–montmorillonite nanocomposites through controlled uniaxial stretching

In this paper we present the results exhibiting an improvement in the tensile properties of polyvinyl chloride (PVC)–montmorillonite nanocomposites through uniaxial stretching. The clay was dispersed in PVC matrix with the help of dodecylamine. PVC–montmorillonite nanocomposites films containing varying amounts of clay (0–5%) were produced through solution elution technique. The films were stretched uniaxially at a constant temperature of 80 °C in three different steps using controlled loads. X-ray diffraction and stress–strain curves were obtained for both unstretched and stretched films in order to determine the improvement in various properties. The controlled uniaxial stretching of films close to the softening temperature of PVC has resulted in enhancement in the degree of crystallinity in the nanocomposites. This improvement in the structural order has also imparted increase in tensile strength and Young’s modulus of the nanocomposite films.

Thermal aging and oxygen permeation of nylon‐6 and nylon‐6/montmorillonite composites

AbstractNylon/clay nanocomposites are expected materials for the great improvement of various properties with small percent addition of clay; however, the degradation behavior and the long term stability of nanocomposites have been insufficiently studied. During the thermal aging in air atmosphere, Nylon is ordinarily affected by oxygen gas; therefore, the oxygen permeation under thermal aging condition is an important factor for considering the thermal degradation of Nylon. Moreover, to examine the relationship between the thermal degradation and the oxygen permeation, the oxygen permeation should be measured at the temperature higher than the temperature of respective Tg. According to the oxygen permeation measurement at the temperature of 65°C, the Nylon‐6/MMT nanocomposites indicate lower permeability coefficient than that of neat Nylon‐6 and Nylon‐6/MMT composites. On the other hand, the solubility coefficients of the MMT contained Nylon‐6 were similar to each other and the solubility coefficients were significantly higher than that of the neat Nylon‐6. This characteristic is presumable to be closely related with the thermal degradation of Nylon‐6. In case of the MMT contained Nylon‐6, the permeation of oxygen gas is slower than the case of neat Nylon‐6; however, it is conceivable that the oxygen gas permeates with some interactive influences on Nylon‐6 matrix. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010

Influence of Functionalization of Multi-Walled Carbon Nanotubes on the Properties of Ethylene Vinyl Acetate Nanocomposites

Commercially available multiwalled carbon nanotubes (MWNT) were chemically modified by amine, acid and silane and their ethylene vinyl acetate (EVA) based nanocomposites were prepared. Unmodified and modified nanotubes were characterized by thermogravimetry, X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy and transmission electron microscopy. Early degradation of modified nanotubes from the thermogravimetry study proved the presence of functional groups on nanotube surface. Increase in D-band to G-band ratio and a shift in radial breathing mode peaks from the Raman spectra indicated the generation of surface defects due to functionalization and variation in van der Waals force of attraction between nanotube aggregates on modification. The unmodified nanotubes improved the tensile strength by 30% with 4 weight% of filler. Amine modification imparted further increase in strength due to the presence of functional groups on the nanotube surface and the subsequent better dispersion of the nanotubes in the polymer matrix. The silane treatment imparted maximum improvement in various properties of the nanocomposites. The nanotubes provided better thermal degradation stability and also higher thermal conductivity to virgin EVA. The results were well supported by the morphological as well as swelling study of the various samples.

Fiber loading of hardwood pulp by in-situ precipitation of aluminosilicate

Sodium aluminosilicate has been precipitated in-situ as filler on hardwood bleached kraft pulp fibers using papermaker’s alum and sodium silicate. The filler was produced in two ways, first in the absence of the fibers and second in the presence of fibers, i.e. in-situ precipitation of filler. The filler produced in absence of fiber was then added to the pulp slurry. Various pulp and paper properties were compared for direct loading of market filler, fresh filler loading, and filler prepared in-situ with fibers. In-situ precipitation technology provided paper with significant improvements in various properties of paper as compared to fillers directly added to the stock. Bulk and stiffness of the handsheets prepared with in-situ precipitation were much higher as compared to those of sheets prepared with fillers directly added to the pulp. There was no appreciable increase in brightness and whiteness of paper with in-situ precipitation, as an appreciable proportion of filler was precipitated inside the fibers. In-situ filler loaded pulps showed a higher filler retention value as compared to directly filler loaded pulps, as a high dose of retention aid was needed with the fillers directly added to the stock.

Nanostructured Coatings Obtained Via Cationic UV-Curing

Polymeric nanocoatings have drawn considerable attention, in recent years, due to improvements in various properties including scratch resistance, abrasion resistance, heat stability as well as other mechanical properties [1-3].Different meal oxide nanoparticles have been employed s filler, in particular SiO2, TiO2 and ZnO were deeply investigated in literature [4].The use of inorganic particles in the nanoscale range is particularly attractive with the aim of improving the polymer properties by controlling the degree of interaction between the polymer and the nanofiller [5]. As inorganic fillers a range of different metal-oxide particles can be dispersed in the polymeric matrix [6-8]. Particularly attractive is the use of inorganic particles in the nanoscale range with the aim of improving the properties of the polymers by controlling the degree of interaction between the polymer and the nanofillers [9] via a top-down approach.One major problem with nanosized particles is their homogeneous dispersion within the organic matrix avoiding macroscopic phase separation. An in-situ approach of preparing nanoparticles using sol-gel precursors is appealing for this reason; it involves a series of hydrolysis and condensation reactions starting from a hydrolyzable multifunctional metal-alcoxide as precursor for the inorganic domain formation [10] (bottom-up approach).The use of suitable coupling agent permits to obtain a strictly interconnected network preventing macroscopic phase separation. The coupling agent provides bonding between the organic and the inorganic phases, therefore well-dispersed nanostructured phases may result [11] and hybrid organic-inorganic materials are achieved.

Studies on polyethylene pellets modified by low dose radiation prior to part formation

When it is combined with other processing steps, radiation modification of polyethylene pellets prior to conversion into end products (formed parts) has brought about significant improvement of various properties of the polymers and products made from them despite the low cross-linking degree. The physical and chemical changes of the polymers after the radiation modification by electron beam (EB) and gamma ray at low dose levels are studied using various characterizations. Fourier Transform Infrared Spectroscopy (FTIR) showed the formation of carbonyl groups and changes of unsaturated bonds. Gel permeation chromatography (GPC) results indicated broadening of the molecular weight distribution. Rheological analysis in linear visco-elasticity regime showed increased dynamic viscosity and large amplitude oscillatory shear (LAOS) analysis showed increased hysteresis. It is proposed that the radiation at low dose levels and under ambient conditions induces various reactions on the polymer chains including long chain branching, oxidation and changes of unsaturated bonds.

Improvement of various properties of fiber surfaces containing crosslinked polyethylene glycols

AbstractModification of a variety of fabric and fibrous surfaces was achieved by insolubilization thereon of crosslinked polythylene glycols (called POLYTHERM) to impart several useful properties: thermal storage and release, improved resiliency and resistance to oily soiling, static charge, pilling, wear life, and marked increases in hydrophilicity among them. Moreover, these improved properties were durable because up to 70% of the crosslinked polyol was retained after 50 launderings. Such modification was achieved by using average molecular weights of the polyols ranging from 600 to 20,000 by crosslinking with polyfunctional methylolamides (such as DMDHEU) in the presence of acid catalysts by a conventional pad‐dry‐cure textile finishing procedure. The role of crosslink density of the polyol in determining textile properties was determined by evaluation of films derived from crosslinking the polyols and comparison of selected properties.

窒素吸収処理による20%Cr-Mn-Fe合金の材質改善について

窒素吸収処理による20%Cr-Mn-Fe合金の材質改善について