PDF | In the present lime the use of composed materials is very extended, Se ha extendido en la actualidad el uso de materiales compuestos formados por. Request PDF on ResearchGate | On Jan 1, , Martin Estrada and others published Bambú y materiales compuestos. PDF | An overview on the state of the art of metal matrix composites used in the La ciencia de los Materiales Compuestos les confiere algunas propiedades.
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Resumen. Los materiales compuestos formados por polímeros armados con fibras (FRP) están Aunque cada vez se construyen más puentes con materiales. Download as PDF, TXT or read online from Scribd Según el estudio “ Materiales Compuestos” realizado por Nodal Consultants y publicado en el en la. Materiales Compuestos Estructurales e - Download as Word Doc .doc /.docx), PDF File .pdf), Text File .txt) or read online.
We found polyphenols in all parts of the tree. The natural substrate increases crystallization temperature and reduces the crystallinity of low density polyethylene LDPE.
The elasticity modulus is higher for the composite material than for the LDPE. The fibers of this species are a promissing alternative for new products and to reduce the environmental impact of traditional polymeric materials. Se prepararon cinco extractos mezclando la muestra molida con diferentes disolventes en orden creciente de polaridad. El orden de los disolventes empleados fue el siguiente: Hexano, acetato de etilo, acetona, metanol y agua.
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Todos los disolventes empleados fueron grado reactivo. Las dimensiones de la muestra fueron 40x10x0,15mm3.
A partir del espectro de infrarrojo del material compuesto, Figura 6 , se puede observar la presencia de ligninas, fenoles y celulosa provenientes del material de relleno. En la Figura 4 se observa una gran variabilidad en los diferentes cromatogramas indicando la existencia de diferentes compuestos presentes en cada extracto.
Lee et al. Aimin et al. They evaluated CS in experimentally-induced osteomyelitis, showing a reduction in the spread of a Staphylococcus aureus infection. Sano et al. Chitosan biodegradability is another essential factor to consider when selecting biopolymers for tissue engineering.
Lysozyme is the enzyme present in biological fluids responsible for CS degradation in vivo. Lysozyme hydrolyzes the b-1,4 de N-acetylglucosamine bonds close to a glucosamine residue. This results in long polymer degradation periods, delaying in months the in vivo reabsorption of the CS-based material Mao et al.
A fast biodegradation could be achieved by using low DD CS, but limiting cell adhesion. Therefore, the adequate selection of DD for the CS to be used is critical to develop tridimensional scaffolds and control its biodegradation and biocompatibility. The abovementioned properties of CS 42 , together with its demonstrated healing and hemostatic properties, its plasticity for presentation microspheres, membranes and bidimensional films, or in tridimensional scaffolds , flexibility, mucoadhesivity and wettability, also its facility to promote bone formation by cellular osteogenesis at the required site, among other desired properties 43 , support using CS as an excellent polymeric candidate in orthopedical applications, especially for bone tissue engineering Nevertheless, CS is not bioactive as biopolymer and show poor mechanical properties.
All these explains the growing interest on combining the bioactivity and biodegradability of inorganic materials together with the rest of CS properties to obtain new compound materials composites of improved mechanical characteristics also favorable for bone tissue engineering Those hybrid materials have been prepared by different methods, as shown in table 2.
The technique consists in mixing the previously prepared ceramic powder with a CS solution to generate a suspension as homogeneous as possible.
Scaffolds are generated from this mix as porous sponges by freezing and lyophilization 49, Murugan et al. A similar procedure was used by Finisie et al. They started from a paste made up of a mix of HAp, aluminum and CS at different proportions. Due to aluminum toxicity, they transformed it onto sodium aluminate by using a concentrated solution of sodium hydroxide, resulting in the formation of pores wider than mm which were generated by the hydrogen gas released by the reaction.
In this case, a suspension of the solid fraction is mostly obtained in the polymeric matrix with pH near 6 where there is a fraction of CS protonated amino groups enough for solubilization, aiding to include CS into the liquid fraction of the cement.
Afterwards, an injectable viscoelastic paste is prepared, which contains CS incorporated in the liquid fraction of the cement and the solid fraction HAp precursors. Once injected, the paste hardens due to the rise of pH to physiological 7. In this process, the inorganic load becomes physically entrapped in situ hardening within the gel matrix in 5 to 8 min, an interval shorter than for control CPCs The resulting materials also show improved mechanical properties, as resistance to compression of 15 to 25 MPa, higher than the same parameter for the CPC alone Taking advantage of these facilities, some investigations have focused on CS-CPC composites as materials with potential application in bone tissue engineering and for controlled release of therapeutic agents, showing very promising results in periodontal bone defect regeneration In this sense, a vast experience has accumulated on the synthesis and characterization of compound materials by using calcium phosphates as filling materials b-TCP and HAp, treated superficially or not , natural polymers CS, sodium alginate , and acrylics mainly poly acrylic acid, polyacrylamide and poly methyl methacrylate , poly 2-hydroxyethyl methacrylate to restore bone tissue and as potential controlled release systems for active ingredients 64, 65 COATING METHOD Calcium phosphate composites can be obtained as coating by using electrochemical and electrophoretic procedures, which favor the deposition of HAp and CS particles.
This technique commonly known as electrochemical deposition allows preparing hybrid materials at room temperature, which is highly favorable considering the final biomedical application. Recently, Pang et al. To modify the surface of shape memory materials made up of nickel- titanium alloys and protect them from corrosion, Sun et al.
Uso de Los Materiales Compuestos
Redepenning et al. Additionally, some authors have studied the remarkable properties of this technique by using biomaterials as Biovetir II, coated with nanostructured CSHAp composites to improve the implant interaction with cells and its fixation to the subcutaneous tissue 69 , as well as for middle ear reconstruction These can generate practical inconveniences, since the lack of homogeneity can induce inflammatory symptoms by forming voluminous fibrotic capsules of dense or granulated connective tissue.
This originates a strong rejection of the implanted material or changes in the area surrounding the prosthesis. In that sense, the method of in situ precipitation of the bioactive inorganic component inside the polymeric matrix, as referred in several publications as biomimetic or bio-inspired method 71 could be more attractive to prepare this type of composites by permitting to generate much more homogeneous systems.
This procedure is nature-inspired in bone, dentin, egg and mollusk shells, etc. In situ precipitation of calcium phosphates allows controlling the internal architecture structure and the chemical composition of the resulting materials. This procedure is based on obtaining nanostructured and crystalline composites of the biologically active component calcium phosphate , homogeneously disperse in the polymeric matrix CS to mimic the biological apatite of the bone tissue.
This supports its application in bone tissue engineering, specifically in targeted bone regeneration 72 , and controlled release of drugs 73 and biologically active molecules These materials have being traditionally prepared by several methods. Yamaguchi et al. Fan et al. Hu et al. Rusu et al.
In that process, pH of the CHI solution and saline precursors CaCl2 and NaH2PO4 were gradually increased by adding a sodium hydroxide solution, and composites of a high degree of structural organization were obtained by using soluble saline precursors equation 1. The same group suggested the use of salts and weak acids as precursors of calcium and phosphate ions, instead of strong acids or bases to avoid their potential destructive effect on the polymeric chains of CS during composite preparation.
Chang et al. Noteworthy, each of the methods referred generates a particular type of CS and HAp composite material, with specific structural properties. The use of citric acid dissolutions as solvent is questionable in spite of the similarity of the apatite phase to that of the final composite, since it inhibits HAp transformation while nucleating amorphous calcium phosphates. Besides, there was also mentioned in the literature that citrate ligands can affect crystal and cell size because of including carboxyl groups Equations 2 and 3 describe the formation steps of the non-stoichiometric apatite obtained in situ, within the polymeric CS matrix.
However, after hydrolysis with Na3PO4, much smaller crystals were obtained by formation of the expected apatite phase calcium-deficient HAp , achieving a complete transformation of one crystalline phase into the other.
We have recently prepared via in situ composites of CS with non-stoichiometric HAp incorporating silicate ions to generate a material of higher osteointegration to the biological system The load of antibiotics and other active principles for example, growth factors into these types of tridimensional matrices could be a way to increase cell proliferation, with faster and more efficient formation and mineralization of the bone tissue.
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The biodegradable, biocompatible and bone-conductive performance of these composite materials is very relevant for future medical applications In general, the inorganic reinforcement of this type of composites should provide simultaneously bioactivity together with resistance and rigidity to the resulting material, the polymeric matrix functioning as filling.
However, it has been demonstrated that the properties of the generated material, the biological properties included, can be improved by incorporating CS Several factors can be involved: physical-chemical dissolution, physical breakdown of bigger molecules into smaller ones by biological agents as enzymes 90 what decreases pH at the site 91 , or the properties of the polymeric matrix used, among others 92, In the same line of evidence, Yang et al.
Nevertheless, Freier et al. Similarly, Chatelet et al. Results show an increasingly faster degradation rate by increasing composites CS content. The hydrophilic nature of the CS polymeric matrix generates a low crystallinity in composites, subsequently rising the solubility of the system, the dissolution speed and the release of calcium ions to the medium.
This supports a gradual rise of bioresorption resulting from the increased biopolymer content within the composites It is affected by reaction conditions, such as: concentration, temperature, pH, 3D conformation, time and filling-matrix interaction.
Generally, composite morphology can widely vary depending on the geometric versatility provided by the polymeric matrix films, micro and nanoparticles, membranes, cements, etc. A relevant aspect is the apatite phase obtained on the surface of the composites, which frequently appears as globular aggregates or clusters of tiny crystals with different characteristics depending on the predominant inorganic component in the given composite For example, b-TCP is presented as prism-like particles, the octocalcium phosphate as small clustered plaques, quite similar to the non-stoichiometric HAp, and DCPD as wide, flattened crystals of great size, and calcium deficient HAp generally appearing as thin and small needles projected from a central point Figure 4 Crystallinity and the inorganic phases present are assessed by X-ray diffraction, and Ca and P content determined by energy dispersive spectroscopy, while the composition of the system is evaluated by thermogravimetry and differential thermal analysis The individual components of CS calcium phosphate composites show a stable physical-chemical identity; in other words, they are neither dissolved nor completely fused one into the other.
Thus, there can be independently identified the inorganic phase and the polymeric matrix. Nevertheless, they can interact through the reactive amino groups on CS and the phosphate and hydroxyl groups and calcium ions on the HAp Calcium phosphate and CS composites have shown to be biocompatible in biological assays with different cell types In another experimental setting, HAp composites based on CS and alginate and soaked with drugs showed effective as local delivery systems in vitro Additionally, bioactivity is the ability to support the formation of a biologically active carboHAp layer onto its surface, facilitating the interface junction with the bone tissue and guaranteeing a close attachment to the bone without an interposed fibrotic capsule.
Hence, the inorganic phase to be integrated should be chemically and structurally similar to the mineral phase of the bone. Biodegradability is another relevant property for tissue engineering systems, also considered for its selection and with CS positively contributing to it. By these means, a dynamic process of formation and resorption of bone tissues is established, where these materials serve as scaffolds for tissue infiltration and replacement, simultaneously stimulating cell growth within Recently, porous tridimensional scaffolds of calcium phosphate and CS composites were generated for bone tissue engineering , Zhao et al.
Additionally, the group of Zhang et al. Only osteoblast cells were able to proliferate or differentiate within all the composite materials phenotypic proliferation. The use of CS scaffolds together with calcium phosphate bioglass avoid the fast degradation in the physiological medium, this process releasing acid byproducts which could affect the osteoblast differentiation Also Zhao et al.
Results showed cell proliferation, de novo formation of bone tissue and mineralization of the obtained scaffolds in only 3 weeks The proper selection of the components for the system to be designed will be determined by the final application of the scaffold. Nevertheless, their availability as granules or blocks, the mechanical weakness of CPCs and the slow resorption or degradation in vivo of all these materials limit their application and the useful lifespan of the material with adequate characteristics, both short and long term in the host organism.
Composites formulations based on natural polymers as CS and the range of preparation methods available allowed obtaining materials of improved and fitted design, of increased strength and improved bone-conductivity, homogeneity, bioactivity, biodegradability and similar to the bone tissue to be repaired or replace.
All these widen their application in the fields of orthopedics and traumatology, more than precedent materials. Current trends tend to develop composite tridimensional scaffolds of improved properties, starting from inorganic materials of higher biodegradability and bioactivity for example, Si-doped non-stoichiometric HAp and incorporating antibiotics and other active principles e.
Hardiman H. Osteoporosis: The lifelong risks. Practice Nursing ; Ochoa F, Pereira O.
Rev Cubana Endocrinol ;8 2 Fallecidos por fractura de cadera en la provincia de Matanzas. Hidroxiapatita porosa Coralina Hap Rev Cenic Cienc Biol ; 36 Especial Cancerous bone repair using bovine trabecular bone matrix particulates. Biomaterials ;23 2 Bohner M.
Calcium orthophosphates in medicine: form ceramics to calcium phosphate cements.
Injury ;S-D Orlovskii V, Barinov S. Hydroxyapatite and hydroxyapatite-matrix ceramics. J Inorg Chem ;S Hydroxyapatite coating by sol-gel on Ti-6Al-4V alloy as drug carrier.
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J Mater Sci Mater Med ; Implantation of cuban granulated hydroxyapatite Apafill-G in pericapical bone defects. Bioceramics ; Filling of post-extraction dental socket with hydroxyaptite granules Apafil-GTM. Key Eng Mater ; Transformation mechanism of different chemically precipitated apatitic precursors into betatricalcium phosphate upon calcinations.
Biomaterials ; Ceramics for medical applications. J Chem Soc Dalton Trans Liou S, Chen SY. Transformation mechanism of different chemically precipitated apatitic precursors into beta-tricalcium phosphate upon calcinations.
La Serna AA. Klein CPAT. Calcium phosphate implant materials and biodegradation. In: Academish Proefschrift.One of the most common and familiar composite is fibreglass , in which small glass fibre are embedded within a polymeric material normally an epoxy or polyester.
Define the Warp and Weft values for the fibers meshes. Removing Ply Shells from a Ply 1. Universidad de Composites Design Version 5 Release 15 Page 3. Right-click on Ply. Click on the Multiselection icon at the left of the Splicing Curves field.
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