1,720,972 research outputs found
Industrial paper recycling process. Suitable micronization for additive polymer application
Get PDFThe traditional paper recycling process has problems related to the disposal of sludge and waste, the use of incinerators and water treatment. Because of that, an interesting alternative proposed from dep. of chemical and materials engineering of Sapienza University of Rome to Carlucci industrial typography, is using paper as filler in thermoplastics or recycled thermoplastic matrix composite. In this way it’s possible re-use paper, but it also possible reduces the amount of polymer with equal volume. The paper has to be subjected by grinding. The chosen grinding process is fundamental to obtain a suitable product for composite. After a pre-grinding process obtaining 5-10 mm of paper fragments, the charge have to be subjected to a micronization process. In this study are selected two different type of micronization: the superfine grinding mill SF, a micronization process based on system that uses simultaneously the impact and friction action, and a knife mill that uses instead the cutting and friction action. Thanks to the first process, it is possible obtaining fibres with diameters of about 15-20 microns and lengths of the order of 250-500micron: a product therefore suitable for the application of filler in composites. This process unfortunately causes the production of fluff, as will shown in figure 2, because of the interfibrillar bonds between the fibers: an optimal dispersion of the fibers is necessary to avoid agglomerates which would decrease the composite properties. From the second process it is possible to obtain both fiber than particles as illustrated in figure 3. This morphologies mix allows to achieve a higher fluency preventing agglomerates. The turbomixer equipment realizes the production process of the composite, this process allows to introduce a higher percentage of filler respect the traditional injection moulding technique. The resulting composite is subjected by a morphological and mechanical characterization: look at the SEM analysis of the fracture surface, the fiber-matrix interface is weak, in spite of this, however, from the tensile test there is a constant elastic modulus and in some cases growing respect to the matrix devoid of fibres. From these results, the importance of optimize the grinding and micronization processes is clear and there is the opportunity of additives introduction to improve fiber-matrix interface
Paper fiber and wood flower surface soaking attack. A previous study for WPC materials improvement
No full textDuring last decades, natural fillers additions to polymeric matrixes have been developed, in particular Wood Plastic Composites achieved great importance thanks to their properties and possibility to use waste material for their production. Another source of waste product is paper, potentially useful as filler in polymeric matrixes. In order to improve fillers-matrix interface many efforts have been done, among which the use of surface modification is one of the most used. Chemical treatment with NaOH, has been used in this work, analysing the effect of several soaking time on different natural fillers
Polymeric matrix composites at reduced environmental impact
No full textThis work focused on the use of bio-derived charge, in order to reduce the environmental impact of traditional oil-based polymers (HDPE in this case). In fact, we introduced waste paper fibres and a starch-derived polymer in Wood Plastic Composites (WPC). We produced different materials: 10 wt% of recycled paper fibres (10F), 30 wt% of wood flour (30W) and a mix of two fillers (30W10F). Polyethylene-graft-maleic anhydride (MAPE) has been introduced as compatibilizer and a NaOH immersion treatment on both cellulosic filler has been done in order to improve composites properties. A starch-derived polymer was then added to the matrix to reduce HDPE amount (30W10F15S). Samples were produced through turbomixing followed by compression moulding technique, and then subjected to tensile tests, SEM analysis, water absorption tests and hardness tests (Shore D). Results evidenced a synergic effect of both cellulosic fillers, and the best results were obtained for 30 wt% wood, 10 wt% fibre of paper, and 3 wt% of MAPE, in which MAPE addition improved interfaces. Samples with starch-derived polymers have shown typical blends morphologies, and cellulosic fillers treated with NAOH revealed an effective attack. The hardness measure displayed that the presence of cellulosic recycled fibres increased both superficial hardness of the composite and temperature resistance, while the presence of starch-derived polymer and fibres treated with NaOH caused a higher softening effect. © 2017 Society of Plastics Engineers
Dual morphology (fibres and particles) cellulosic filler for WPC materials
Get PDFWood-plastic composites (WPC) were fabricated by using a polyethylene (PE) matrix and filling it with wood flour in the amount of 30 wt.%, and compared with the same composites with further amount of 10 wt.% of cellulosic recycled fibres added. The materials were produced by turbomixing and subsequent moulding under pressure. Mechanical properties of both WPC and WPC with cellulosic recycled fibres were evaluated through mechanical and physical-chemical tests. Tensile tests clarified that a moderate reduction is strength is observed with the bare introduction of wood flour with respect to the neat PE matrix, whilst some recovery is offered by the addition of recycled cellulose fibres. Even more promisingly, the elastic modulus of PE matrix is substantially improved by the addition of wood flour (around 8% on average) and much more so with the further addition of recycled cellulose (around 20% on average). The fracture surfaces from the tensile test were analysed by scanning electron microscope (SEM) indicating a reduction in microporosity as an effect of added cellulose. The water absorption test and the hardness measure (Shore D) were also performed. SEM analysis underlined the weak interface between both wood particle and cellulosic recycled fibres and matrix. The water absorption test showed a higher mass variation for pure WPC than WPC with cellulosic recycled fibres. The hardness measurement showed that the presence of cellulosic recycled fibres improves both superficial hardness of the composite and temperature resistance. © 2016 Author(s)
Eco-friendly approach and potential biodegradable polymer matrix for WPC composite materials in outdoor application
Get PDFBlends based on high density polyethylene (HDPE) and poly(lactic) acid (PLA) with different ratios of both polymers were produced: a blend with equal amounts of HDPE and PLA, hence 50 wt.% each, proved to be a useful compromise, allowing a high amount of bio-derived charge without this being too detrimental for mechanical properties and considering its possibility to biodegradation behaviour in outdoor application.
In this way, an optimal blend suitable to produce a composite with cellulosic fillers is proposed. In the selected polymer blend, wood flour (WF) was added as natural filler in the proportion of 20, 30 and 40 wt.%, considering as 100 the weight of the polymer blend matrix. Two compatibilizers to modify both HDPE-PLA blend and wood-flour/polymer interfaces i.e. polyethylene grafted maleic anhydride and a random copolymer of ethylene and glycidyl methacrylate. The most suitable percentage of compatibilizer for HDPE-PLA blends appears to be 3 wt.%, which was selected also for use with wood flour. In order to evaluate properties of blends and composites tensile tests, scanning electron microscopy, differential scanning calorimetry, thermo-gravimetric analyses and infrared spectroscopy have been performed. Wood flour seems to affect heavy blend behaviour in process production of material suggesting that future studies are needed to reduce defectiveness
Use of recycled milled-paper in HDPE matrix composites
No full textThe traditional paper recycling process has problems related to the disposal of sludge and waste, the use of incinerators and water treatment. Because of that, an interesting alternative is using
paper as filler in recycled thermoplastics matrix composite. In this way, re-use of paper is possible, and consequently the reduction of the amount of polymer with equal volume. The paper has to be subjected by micronization for this application. The micronization process adopted is based on system that uses simultaneously the impact and friction action. The production process of the composite is realized by the traditional injection moulding. The resulting composite is subjected by a morphological and mechanical characterization: from SEM analysis of the fracture surface was clear the absence of fiber-matrix interface, in spite of this, however, from tensile tests there is a constant elastic modulus and in some cases growing respect to the matrix devoid of fibres
Paper fiber filled polymer. Mechanical evaluation and interfaces modification
No full textThe aim of this work is to introduce recycled paper in HDPE matrix composites, an interesting alternative to traditional recycling process for paper. This strategy allows both re-using paper and reducing the amount of virgin polymer used in the same volume. For this application, the recycled paper goes through a micronization process, which uses simultaneously the action of impact and friction. The production of the composite is realized either by traditional injection moulding or by turbomixing. The best fibres' dispersion was obtained by turbomixing and the composites produced in this way have been additivated with maleated polyethylene (MAPE) in the amounts of 1, 3 and 5 wt.%. The resulting composites with 10 wt.% fibres were characterized from the morphological and mechanical point of view. Tensile tests revealed a rather constant stiffness and some improvement of strength with respect to the neat matrix, also indicating that the best results were obtained by the addition of 1 wt.% MAPE. SEM micrographs evidenced that, in the absence of additive, fibre-matrix interface was rather weak. In addition, the samples with added MAPE appear to experience a reduction in microporosity, which was confirmed also by water absorption test
Optimization of thermoplastic blend matrix HDPE/PLA with different types and levels of coupling agents
Get PDFHigh-density polyethylene (HDPE) and poly(lactic) acid (PLA) blends with different ratios of both polymers, namely, 30:70, 50:50, and 70:30, were produced. Polyethylene-grafted maleic anhydride and a random copolymer of ethylene and glycidyl methacrylate were also considered as compatibilizers to modify HDPE/PLA optimal blends and were added in the amounts of 1, 3, and 5 wt.%. Different properties of the blends were evaluated by performing tensile tests and scanning electron microscopy to analyze blend and interfaces morphology. Moreover, thermomechanical analysis through differential scanning calorimetry, thermo-gravimetric analysis, and infrared spectroscopy were also performed. The blend containing equal amounts of HDPE and PLA seemed to present a good balance between amount of bio-derived charge and acceptable mechanical properties. This suggests that these blends have a good potential for the production of composites with lingo-cellulosic fillers
Electroless plating on graphene (GNPs) for surface modification and composites applications
No full textIntroduction
Carbon nanotubes (CNTs) and graphene nanoplatelets (GNPs), are two of the most interesting carbon nanostructures (CNSs) usable as reinforcement in metal matrix composites material manufacturing because of their excellent mechanical properties.
Aluminium and magnesium are the most studied light weight metals used as matrices in metal composites principally to their low density (respectively 2.7 g/cm3 and 1.7 g/cm3) and low melting temperature (around 660 °C for both metals). The improvement of mechanical properties of these structural metals allows to obtain environmental and technical benefits thanks to the possibility to reduce the global weight of different type of vehicles.
However, carbon structures have a poor wettability with liquid aluminium and magnesium causing many technical problems during manufacturing process of composites.
Nickel is one of the most used metals that exhibits a great affinity with aluminium and magnesium and it is successful used to the application of a functional coating onto the surface of the CNSs in order to improve their wettability by molten metal matrix.
In this work, pure aluminium and magnesium alloy (AZ63) composites were produced with modified GNPs.
Material and Methods
GNPs were functionalized with coating through a new electroless pure nickel deposition using hydrazine instead of hypophosphite as reducting agent. Powder metallurgy method was applied for composites production: GNPs, modified with nickel, were mixed with aluminium or magnesium powders and then melted and casted in induction furnace with centrifugal casting system in inert atmosphere.
Nickel effects on fillers-matrix interfaces was investigated by SEM and EDS analysis. Composites mechanical properties were evaluated by four-point flexural tests.
Results
An improvement of aluminium and magnesium alloy wettability on GNPs coated with nickel was shown and a better dispersion of fillers was exhibited compared to uncoated one.
Discussion
The coating of GNPs made with a nickel solution containing hydrazine than hypophosphite seems to modify significantly the GNPs metallic interface, moreover it allows to obtain a good dispersion of the reinforcements in the matrix avoiding formation of agglomerates
HDPE-soy protein isolate (SPI) blends. First results and future perspectives
No full textOil-based/bio-derived blends have been produced with high-density polyethylene (HDPE) and Soy Protein Isolate (SPI). In order to be processed, SPI is plasticized with glycerol. In order to overcome different hydrophilicity between natural and oil-based polymers, a compatibilizer has been introduced. Polyethylene-graft-glycidyl methacrylate (PE-g-GMA) has been selected to act on HDPE-SPI interface. Good effect of PE-g-GMA has been displayed, increasing tensile strength, keeping almost the same elastic modulus and elongation at break. SEM images confirmed an increased toughness for HDPE-SPI based blends when glycerol is added
- …
