Amount Of Polypropylene Research Articles

Study on flexural behaviour of printed concrete wide beams using polypropylene fibres

Sustainability in building construction is an inevitable aspect of future construction projects. The justification of sustainability is highly appreciated by comparing 3D concrete printing technology with conventional construction. However, the 3D printing concrete system has limitations and challenges in industrial applications. The reason is that this process was initially used in small non-structural applications and is now being adopted for large-scale structures. Thanks to concrete printing machines, a wide variety of web frames are also available - something completely impossible to achieve using traditional formwork for pouring concrete. In this study, the girder web is designed in the style of truss beams. Three wide beams with different amounts of polypropylene (PP) fibre were printed, and 3-point loading tests were conducted. The failure mode, load-bearing capacity, and deflection were reported in this study. According to the results, applying concrete printing technology in civil and industrial construction is entirely feasible. The printing process successfully produced models with a nozzle diameter of 22 mm and layer height of 10 mm, ensuring sufficient adhesion force between the printing layers. Using a PP fibre content of about 0.25% yielded the best results in terms of concrete compressive strength and beams’ flexural strength, while a PP fibre content of about 1.00% tended to increase the ductility of the member. Although the failure mode is brittle, the beams exhibited deflection before fracture far beyond the allowable deflection value of a flexural member. Therefore, the application of printed components to construction is feasible.

The Characteristics of Polymer Concrete Reinforced with Polypropylene Fibres Under Axial and Lateral Compression Loads

The use of cement is expected to increase over the years as the infrastructure continues to develop, and the needs to repair or rehabilitate an old and deteriorated building are necessary. However, many investigations have been conducted to establish promising polymer concrete applications in the last few decades. Meanwhile, using concrete in the construction industry has led to environmental issues. It is because relying on cement production in concrete will contribute to about 7% of the world’s carbon dioxide emissions. Therefore, polymer concrete was introduced in this study to minimise the use of cement in the industry. This research investigated the influence of different amounts of polypropylene (PP) fibre content on polymer concrete (PC) properties by determining the compressive strength, flexural strength and indirect tensile strength. Furthermore, the results of PC failure characteristics have been discussed. The polymer concrete specimens in this study have been cast into cylinders and prismatic specimens using PVC pipe and plywood formwork to determine the compressive strength, splitting tensile strength and flexural strength. By reinforcing PP fibre in the polymer concrete with a specific percentage of fibre reinforced, the overall strength of the polymer concrete was improved. Based on the compressive, splitting tensile, and flexural test results, it has been hypothesised that the 0.16% PP fibre will considerably improve polymer concrete. Additionally, PP fibre maintains a moisture content of less than 0.5% in the aggregates, resulting in a significant enhancement in the mechanical properties of polymer concrete.

Superhydrophobicity of composite surfaces created from polymer blends

HypothesisWhen they are used alone, some polymers, such as polypropylene, Carnauba wax or polycarbonate allow the creation of superhydrophobic surfaces by spin coating or casting. On the other hand, some other polymers, such as polystyrene, polyvinylacetate or polychloroprene, are unable to render a superhydrophobic surface by these techniques. Using binary mixtures of these two types of polymers in a single common solvent, superhydrophobic composite surfaces can be created. We aim to show that superhydrophobicity is depending on the ratio between the two polymers in the initial blend and their intrinsic wettability. ExperimentsThe transition towards superhydrophobicity is studied on composite surfaces made of various polymers. Surfaces are created with simple coating methods, such as casting or spin-coating, of polymer solutions and letting the solvent evaporate at ambient conditions. FindingsTransitions are sharp and the amount of polypropylene in the blend to achieve superhydrophobicity decreases with the hydrophobicity of the second polymer. Topographic and wettability measurements are performed that show that both effects, topographical and chemical, interplay in the property of superhydrophobicity.

Hybrid materials obtained by in situ polymerization based on polypropylene and mesoporous SBA-15 silica particles: Catalytic aspects, crystalline details and mechanical behavior

Nanocomposites based on polypropylene have been prepared by in situ polymerization of propene in presence of mesoporous SBA-15 silica. Synthetic reactions were carried out with a zirconocene catalyst under either homogenous or supported conditions, the SBA-15 particles being used as carriers, and testing the immobilization of the catalytic system by several approaches. The existence of polypropylene able to crystallize within the mesoporous channels in the resulting materials is initially figured out from the appearance of a small endothermic process on heating calorimetric experiments, located at around 100 °C. The presence of polypropylene crystallites confined within the SBA-15 mesostructure is thereafter confirmed by SAXS measurements through the intensity variation of the SBA-15 first order reflection, this change being dependent on composition. Accordingly, polypropylene chains can grow up either outside or inside the SBA-15 channels during polymerization and the mesoporous particles maintain their ordered hexagonal arrangement. Mechanical response, as deduced from indentation measurements, improves with SBA-15 incorporation (without varying the final processing temperature). Thus, stiffness increases and deformability is reduced in the nanocomposites as the SBA-15 content rises. Simultaneously, polypropylene amount within channels is enlarged. Amount of SBA-15 is, then, the most important variable.

Thermomechanical Properties of Polypropylene-Based Lightweight Composites Modeled on the Mesoscale

A waste-based particle polymer composite (WPPCs) made of foam glass and polypropylene was developed as a low-cost construction material. Thermomechanical properties of the composite, including creep properties of WPPC and polypropylene binder, were examined. By adding a relatively small amount of polypropylene to foam glass (about 2:8 in volume parts), the maximum bearing capacity at room temperature of the composite increased from 1.9 (pure foam glass) to 15 MPa. A significant creep strain accumulated during compressive loading of WPPC (5 MPa) in the first 2000 s at elevated temperatures (40, 60 °C). In the study, Kafka’s mesomechanical model was used to simulate creep strain changes in time for various temperatures. The applicability of Kafka’s mesomechanical model for simulating creep properties of the studied composite material was demonstrated.

Mechanical properties and durability of high-strength concrete containing macro-polymeric and polypropylene fibers with nano-silica and silica fume

The current study investigates the effects of different amounts of polypropylene (PP) and macro-polymeric (MP) fibers on the mechanical properties and durability of high-strength concrete containing silica fume and nano-silica. In total, 280 concrete specimens were produced in 28 different test groups, for which the parameters of compressive strength, tensile strength, modulus of elasticity, water absorption, and porosity were evaluated. The macro-polymeric fibers in volume fractions of 0.25, 0.5, 0.75, 1.0, and 1.25%, and the polypropylene fibers in volume fractions of 0.1, 0.2, 0.3, 0.4, and 0.5% were used in this study. Furthermore, one set of specimens with the total fiber volume fraction of 1.0% of the concrete volume was tested in order to examine the effect of hybrid polypropylene-macro-polymeric fibers on the concrete properties. In addition, the nano-silica with the weight percentages of 1, 2, and 3%, and the silica fume with the weight percentages of 8, 10, and 12% were employed in the concrete mix design. In the current paper, first, the effects of macro-polymeric, polypropylene, and hybrid fibers on the physico-mechanical properties were comparatively examined, and then the influence of using nano-silica and silica fume in the high-strength concrete with no included fiber was investigated. Finally, the optimum percentages of fibers and pozzolans corresponding to the most significant increases in the tensile strength were chosen, which were subsequently used as the optimum combination of the high-strength concrete. The results of the experimental study suggest an improvement in the concrete mechanical properties and durability following the introduction of nano-silica and silica fume. In addition, incorporating macro-polymeric fibers in the concrete mixture given the volume content of fibers improves the mechanical properties of high-strength concrete. Moreover, high volume fractions of polypropylene fibers in the concrete mixture brought about negative effects on the physico-mechanical properties of the high-strength concrete.

Torque rheometry and rheological analysis of powder–polymer mixture for aluminum powder injection molding

Selection of desired powder–polymer mixture (feedstock) formulation is a key factor in manufacturing perfect parts via powder injection molding. In the present study, feedstock characteristics of an aluminum-based powder were investigated by torque rheometry and rheological analyses. Several binders containing various amounts of polypropylene (PP), paraffin wax (PW), and stearic acid (SA) were selected for torque mixing and viscosity evaluation. Then, feedstocks consisting of 54, 58, 62, and 66 vol. % solid contents were prepared with modified binder. Feedstock flow behaviors were investigated regarding the rheological parameters such as mixing torque, viscosity, flow behavior index, flow activation energy and moldability index. It was found that increasing solid loading from 54 to 62 vol. % led to improved rheological behavior. This improvement was not observed in high solid contents, i.e., 66 vol. %. Based on experimental results, the optimized binder composition (60PW,35PP,5SA vol. %) and the optimum powder loading (62 vol. %) were selected as the best formulations for injection of aluminum powder. These values are supported by critical powder volume concentration measurements deduced from the oil absorption method. The resulting aluminum molded green parts with no defects exhibited the straightforward injection molding process of selected feedstock.

Determination of the Optimal Polypropylene Fiber Addition to the Dense Bituminous Mixtures by the Aid of Mechanical and Optical Means

Polypropylene fibers are completely native modifiers and they do not have any dependence on abroad in case of technology. When viewed from this point, the modification of bituminous binders with polypropylene fibers is a very important step for our country’s “economical” concerns. In this study, first of all, the physical and chemical effects of polypropylene fibers on bitumen were investigated. Next, the amount of “optimum” polypropylene fibers that has to be added into the mixture was determined. In order to determine it, first, static creep tests and Marshall tests were carried out and then, images of the polypropylene fiber added bituminous binders under fluorescence microscopy were researched. With the application of physical and mechanical tests to the Marshall specimens prepared with the optimum polypropylene amount that was obtained, optimum bitumen content was determined and finally economical analyses were carried out. By carrying out extensive analyses it was seen that the utilisation of polypropylene fibers improves the physical and mechanical properties of the resultant asphalt mixture mainly by enhancing the permanent deformation resistance. On the other hand, polypropylene modification results in 30% economy from bitumen which is a clear indication of the benefit in the mass production of asphalt concrete.

Manufacturing of Wood-Plastic Composite from Completely Recycled Materials

In this study, wastes of wood cutting mills (wood flour) as well as wastes of textile industry (granules of polypropylene) were used in manufacturing wood-plastic composites. Hence, wood flour with weight percent of 30, 35 and 40 was mixed with corresponding amount of polypropylene and coupling agent, polypropylene grafted maleic anhydride in amount of 6 percent was used in whole compounds. Production was done by batch method and with employment of hot press and after preparation and cutting of specimens physical and mechanical properties of them was studied. The results showed that with increase of wood flour up to 35 percent, MOR, MOE, water absorption and thickness swelling increases but further than it mechanical and physical properties decreases. Besides, increase of wood flour up to 40 percent increased the hardness of the specimens.

Contribution of cocktail of polypropylene and steel fibres in improving the behaviour of high strength concrete subjected to high temperature

The aim of the study is to improve the understanding of the influence of a polypropylene and steel fibres cocktail on the behaviour of high strength concretes subjected to high temperature. Concrete mixes were studied by adding polypropylene fibres, steel fibres and cocktail of fibres. The concrete specimens were subjected to various heating–cooling cycles. The initial and residual mechanical properties, the porosity and the mass loss of the studied concrete mixes were investigated. Different concretes compositions with various amounts of polypropylene and/or steel fibres were tested. Experimental results show the significant improvement of the residual mechanical properties of concretes containing the cocktail of fibres compared to concretes without fibres.

Sixty-month follow-up after endoscopic inguinal hernia repair with three types of mesh: a prospective randomized trial

This prospective, clinical, randomized, double-blind study was intended to investigate the impact of the structure and the amount of polypropylene (PP) mesh used in laparoscopic transabdominal preperitoneal hernioplastic (TAPP) on physical function and life quality. 180 male patients with primary inguinal hernia undergoing TAPP were randomized for using a heavyweight (108 g/m(2)), double-filament PP mesh (Prolene, 10 x 15 cm, group A, n = 60), a multifilament, heavyweight variant (116 g/m(2)) of PP mesh (Serapren, 10 x 15 cm, group B, n = 60), or a composite mesh (polyglactin and PP) (Vypro II, 10 x 15 cm, group C, n = 60). We compared in terms of complications (seromas, recurrence rate) and life quality (pain development, physical function). The development of life quality was documented according to the SF-36 Health Survey. The follow-up period was 60 months. The recurrence rate (2.2% overall) during 60-month follow-up was not significantly different between the groups. Convalescence in group A was slower than in groups B and C: mean-term values of the visual scales for pain development were significantly (p < 0.05) higher, incapacity for work was 8.2 days longer, and urological adverse effects were stronger. The mean-term development of life quality was significantly lower in group A up to 12th week postoperatively. There were no significant differences between groups B and C. Beyond the 12th postinterventional week the differences diminished. The composite mesh does not provide an advantage concerning physical function or pain development in comparison to the multifilament, heavyweight, pure polypropylene mesh. Independently of which mesh was implanted 5% of patients are still suffering from discomfort after 5 years.

Microporous polypropylene fibers containing fine particles of poly(styrene-co-divinylbenzene) or poly(glycidylmethacrylate-co-divinylbenzene)

Styrene-divinylbenzene or glycidylmethacrylate-divinyl-benzene were copolymerized in powdery polypropylene suspended in water and the resultant polymer composites were blended with a definite amount of polypropylene. The products consisted of polypropylene and the fine particles of the copolymer, which were uniformly dispersed in polypropylene phase. These products were melt-spun to prepare polypropylene fibers containing the fine particles and then the fibers were stretched to make the fibers microporous. Some properties were estimated: porosity, 1.6–19.7%; average pore size, 0.004–0.009 µm; and specific surface, 9–137 m2/g. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 722–727, 1999

Some mechanical properties of solvent‐treated polypropylene films

AbstractThe amount of polypropylene (PP) extracted by hot solvent extraction increased with increasing naphtha in a naphtha/reformate solvent blend. The stress–strain curves formed the basis for the calculation of several mechanical properties of the residual film. The yield stress, the natural draw ratio, secant modulus, breaking factor, and work expended in drawing were maximum at a 10/90 naphtha/reformate composition. These were explained in terms of extraction of low molecular weight and atactic materials leaving a more stereoregular block, giving maximum properties with the least removal of polymer materials. Further increases in the naphtha component, however, decreased these properties, possibly due to the greater solubilizing effect of naphtha for the PP chains. © 1995 John Wiley &amp; Sons, Inc.

Blend rules for homogenous and heterogenous systems

AbstractBlend rules for (a) homogeneous and (b) heterogeneous systems are proposed in a form of P = (ϕm1P1 + ϕm2P2)/(ϕm1 + ϕm2), where P is the property, and ϕ, the volume fraction of component 1 or 2. For (a) m&gt;1 and for P2&gt;P1, an S‐shaped relation occurs between P or ϕ1. On the contrary, for (b) m&lt;1, an anti‐S‐shaped relation occurs. When the hard component forms particles in continuous soft media, P is larger than the arithmetic mean P̄. When the interface slips, a mean of harmonic function holds so that 1/P = ϕ1/P1 + ϕ2/P2 and P &lt; P̄. For special cases, i.e., the filler in the rubber and the rubber particles in the resin, the strength at break attains a maximum at 20 and 13% of particles, respectively. For rubber blended with a small amount of polypropylene by dynamic vulcanization, the latter forms a continuous phase, reinforcing rubber domains by the plastic force when the size of rubber particles becomes very small. © 1994 John Wiley &amp; Sons, Inc.

Polyolefin blends: 2. Effect of EPR composition on structure, morphology and mechanical properties of iPP/EPR alloys

The morphology, thermal behaviour, tensile and impact properties of sheet specimens of isotactic polypropylene (iPP) blended with ethylene-propylene copolymers (EPR) containing different amounts of polypropylene or polyethylene blocks and various extents of crystallinity were investigated by means of optical and scanning electron microscopy, differential scanning calorimetry, wide-angle X-ray diffractometry, impact and tensile mechanical tests. The experimental results showed that copolymers containing polypropylene or polyethylene blocks could act as nucleating agents for iPP spherulites. It was found that the mode and state of dispersion of the EPR copolymers, as well as the thermal and mechanical behaviour of the blends, depended upon the composition of the copolymer used in the blends for given crystallization conditions. The observed behaviour is very similar to that reported for high-density polyethylene/ethylene-propylene copolymer blends in the first paper of this series. This allows us to discuss the results in terms of the generalized behaviour of such polyolefin blends.

Pyrolysis of polypropylene in the presence of a halogenated alkane, antimony oxide and a bismuth salt: Some aspects of the degradation mechanism

Many mixtures with various amounts of polypropylene and two commonly used flame retardant additives were pyrolysed at temperatures from 400 to 900°C for different lengths of time. The additives where Cerechlor 70 with Sb 2O 3 and Cerechlor 70 with (BiO) 2CO 3. Comparison of the pyrograms of these mixtures with that of polypropylene led to the conclusion that in the presence of these additives two different kinds of condensed-phase reaction occur. Some aspects of the degradation mechanism and of the synergistic effect of these additives are discussed.