Development and Characterization of Calcium Based Biocomposites Using Waste Material (Calcite Stones) for Biomedical Applications

Calcium-based biocomposite materials have a pivotal role in the biomedical field with their diverse properties and applications in combating challenging medical problems. The study states the development and characterization of Calcium-based biocomposites: Hydroxyapatite (HAP), and PVA-Gelatin-HAP films. For the preparation of Calcium-based biocomposites, an unconventional source, the waste material calcite stone, was used as calcium raw material, and by the process of calcination, calcium oxide was synthesized. From calcium oxide, HAP was prepared by chemical precipitation method, which was later added in different proportions to PVA-Gelatin solution and finally dried to form biocomposite films. Then the different properties of PVA/Gelatin/HAP composite, for instance, chemical, mechanical, thermal, and swelling properties due to the incorporation of various proportions of HAP in PVA-Gelatin solution, were investigated. The characterization of the HAP was conducted by X-ray Diffraction Analysis, and the characterization of HAP-PVA-Gelatin composites was done by Fourier Transform Infrared Spectroscopy, Thermomechanical Analysis, Tensile test, Thermogravimetric Differential Thermal Analysis, and Swelling Test. The produced biocomposite films might have applications in orthopedic implants, drug delivery, bone tissue engineering, and wound healing.

Isolation of Microcrystalline Cellulose from Wood and Fabrication of Polylactic Acid(PLA)Based Green Biocomposites

An innovative microcrystalline cellulose(MCC)natural fibre powder-reinforced PLA biocomposite was investigated using the hand lay-up technique.The polymer matrix composite(PMC)samples were prepared by varying the weight percentages(wt.%)of both PLA matrix and MCC reinforcement:pure PLA/100:0,90:10,80:20,70:30,60:40 and 50:50 wt.%,respectively.From the results obtained,MCC powder,with its impressive aspect ratio,proved to be an ideal reinforcement for the PLA,exhibiting exceptional mechanical properties.It was evident that the 80:20 wt.%biocomposite sample exhibited the maximum improvement in the tensile,flexural,notched impact,compressive strength and hardness by 28.85%,20.00%,91.66%,21.53%and 35.82%,respectively compared to the pure PLA sample.Similarly,during the thermogravimetric analysis(TGA),the same 80:20 wt.%biocomposite sample showed a minimum weight loss of 20%at 400℃,among others.The morphological study using Field Emission Scanning Electron Microscopy(FE-SEM)revealed that the uniform distribution of cellulose reinforcement in the PLA matrix actively improved the mechanical properties of the biocomposites,especially the optimal 80:20 wt.%sample.Importantly,it was evident that the optimal PLA/cellulose biocomposite sample could be a suitable and alternative sustainable,environmentally friendly and biodegradable material for semi/structural applications,replacing synthetic and traditional components.

Sustainable Biocomposites Materials for Automotive Brake Pad Application:An Overview

Research into converting waste into viable eco-friendly products has gained global concern.Using natural fibres and pulverized metallic waste becomes necessary to reduce noxious environmental emissions due to indiscriminately occupying the land.This study reviews the literature in the broad area of green composites in search of materials that can be used in automotive brake pads.Materials made by biocomposite,rather than fossil fuels,will be favoured.A database containing the tribo-mechanical performance of numerous potential components for the future green composite was established using the technical details of bio-polymers and natural reinforcements.The development of materials with diverse compositions and varying proportions is now conceivable,and these materials can be permanently connected in fully regulated processes.This explanation demonstrates that all of these variables affect friction coefficient,resistance to wear from friction and high temperatures,and the operating life of brake pads to varying degrees.In this study,renewable materials for the matrix and reinforcement are screened to determine which have sufficient strength,coefficient of friction,wear resistance properties,and reasonable costs,making them a feasible option for a green composite.The most significant,intriguing,and unusual materials used in manufacturing brake pads are gathered in this review,which also analyzes how they affect the tribological characteristics of the pads.

In vitro degradation and cytotoxicity of Mg-5Zn-0.3Ca/n HA biocomposites prepared by powder metallurgy

Mg-5Zn-0.3Ca/nHA biocomposites were prepared from pure Mg,Zn,Ca and nano-hydroxyapatite(nHA)powders by powder metallurgy method.The effect of various mass fractions of nHA(1%,2.5%,5%)as reinforcement on the corrosion properties of Mg-5Zn-0.3Ca alloy was investigated.The corrosion resistance of biocomposite samples was investigated by immersion tests and electrochemical techniques in SBF solution.The results showed that the corrosion resistance of Mg alloy was improved by adding 1%and 2.5%nHA.Bioactive nHA motivated the formation of stable phosphate and carbonate layers on surface and improved corrosion resistance of nanocomposites.However,addition of large contents of nHA in Mg alloy as reinforcement increased the density of this precipitated layer,so gases produced from localized corrosion were accumulated underneath this layer and decreased its adhesiveness and lowered its corrosion resistance.Indirect cytotoxicity evaluation for Mg alloy and its nanocomposites also showed that their extraction was not toxic and nanocomposite with 1%nHA indicated almost similar behavior as negative control.

Connecting Calcium-Based Nanomaterials and Cancer:From Diagnosis to Therapy

As the indispensable second cellular messenger,calcium signaling is involved in the regulation of almost all physiological processes by activating specific target proteins.The importance of calcium ions(Ca^(2+))makes its“Janus nature”strictly regulated by its concentration.Abnormal regulation of calcium signals may cause some diseases;however,artificial regulation of calcium homeostasis in local lesions may also play a therapeutic role.“Calcium overload,”for example,is characterized by excessive enrichment of intracellular Ca^(2+),which irreversibly switches calcium signaling from“positive regulation”to“reverse destruction,”leading to cell death.However,this undesirable death could be defined as“calcicoptosis”to offer a novel approach for cancer treatment.Indeed,Ca^(2+)is involved in various cancer diagnostic and therapeutic events,including calcium overload-induced calcium homeostasis disorder,calcium channels dysregulation,mitochondrial dysfunction,calcium-associated immunoregulation,cell/vascular/tumor calcification,and calcification-mediated CT imaging.In paral-lel,the development of multifunctional calcium-based nanomaterials(e.g.,calcium phosphate,calcium carbonate,calcium peroxide,and hydroxyapatite)is becoming abundantly available.This review will highlight the latest insights of the calcium-based nanomaterials,explain their application,and provide novel perspective.Identifying and characterizing new patterns of calcium-dependent signaling and exploiting the disease element linkage offer additional translational opportunities for cancer theranostics.

Synthesis and Structural Characterization of Hydroxyapatite-Wollastonite Biocomposites, Produced by an Alternative Sol-Gel Route

Hydroxyapatite is a type of calcium phosphate-based material with great interest for biomedical applications, due to the chemical similarity between this material and the mineral part of human bone. However, synthetic hydroxyapatite is essentially brittle;the practice indicates that the use of hydroxyapatite without additives for implant production is not efficient, due to its low strength parameters. In the present work, biocomposites of hydroxyapatite-wollastonite were synthesized by an alternative sol-gel route, using calcium nitrate and ammonium phosphate as precursors of hydroxyapatite, and high purity natural wollastonite was added in ratios of 20, 50 and 80 percent by weight immersed in aqueous medium. Formation of hydroxyapatite occurs at a relatively low temperature of about 350?C, while the wollastonite remains unreacted. After that, these biocomposites were sintered at 1200?C for 5 h to produce dense materials. The characterization techniques demonstrated the presence of hydroxyapatite and wollastonite as unique phases in all products.

Novel Mycelium-Based Biocomposites (MBB) as Building Materials

Novel mycelium-based biocomposites(MBB)were obtained from local agricultural(hemp shives)and forestry(wood chips)by-products which were bounded together with natural growth of fungal mycelium.As a result,hemp mycocomposites(HMC)and wood mycocomposites(WMC)were manufactured.Mechanical,water absorption and biodegradation properties of MBB were investigated.MBB were characterized also by ash content and elemental composition.The results of MBB were compared with the reference materials such as the commercial MBB material manufactured by Ecovative®Design(EV),hemp magnesium oxychloride concrete(HC)and cemented wood wool panel(CW),manufactured by CEWOOD®.The mechanical properties of HMC and WMC showed that the bending strength difference was about 30%,with a better result for HMC.Compression strength was better for WMC by about 60%compared to that of HMC.The mechanical strength of HMC and HC materials was equal;both materials contained hemp shives but differed by the binding material.Water absorption and volumetric swelling tests showed that HMC and WMC could be considered as potential biosorbents.Ash content and elemental analysis showed that reference materials(CW,HC)contained significant amounts of inorganic compounds that decreased the biodegradation rate,compared to the case of HMC and WMC materials.The biodegradation results of HMC and WMC,after 12 weeks,revealed a mass loss(ML)above 70%,while in the case of EV,HC and CW,it was about 60%,17%and only 6%,respectively.MBB were completely biodegradable.

Characterization of Formacell Lignin Derived from Black Liquor as a Potential Green Additive for Advanced Biocomposites

Black liquor is obtained as a by-product of the pulping process,which is used to convert biomass into pulp by removing lignin,hemicelluloses and other extractives from wood to free cellulose fibers.Lignin represents a major constituent in black liquor,with quantities varying from 20%to 30%,of which a very low share is used for manufacturing value-added products,while the rest is mainly burned for energy purposes,thus underestimating its great potential as a raw material.Therefore,it is essential to establish new isolation and extraction methods to increase lignin valorization in the development of bio-based chemicals.The aim of this research work was to determine the effect of KOH or ethanol concentration as an isolation agent on lignin yields and the chemical characteristics of lignin isolated from formacell black liquor of oil palm empty fruit bunch(OPEFB).Isolation of lignin was carried out using KOH with various concentrations ranging from 5%to 15%(w/v).Ethanol was also used to precipitate lignin from black liquor at concentrations varying from 5%to 30%(v/v).The results obtained showed that the addition of KOH solution at 12.5%and 15%concentrations resulted in better lignin yield and chemical properties of lignin,i.e.,pH values of 3.86 and 4.27,lignin yield of 12.78%and 14.95%,methoxyl content of 11.33%and 10.13%,and lignin equivalent weights of 476.25 and 427.03,respectively.Due to its phenolic structure and rich functional groups that are favorable for modifications,lignin has the potential to be used as a green additive in the development of advanced biocomposite products in various applications to replace current fossil fuel-based material,ranging from fillers,fire retardants,formaldehyde scavengers,carbon fibers,aerogels,and wood adhesives.

Influence of Glycerol Content on Properties of Wheat Gluten/Hydroxyethyl Cellulose Biocomposites

Environmentally friendly biocomposites were prepared by blending wheat gluten（WG）as a matrix, hydroxyethyl cellulose（HEC）as a filler,and glycerol as a plasticizer,followed by thermo-molding of the mixture at 120°C for crosslinking the matrix.Moisture absorption,tensile properties,dynamic mechanical analysis,and dynamic rheology were evaluated in relation to the glycerol content.Tensile strength and modulus drop dramatically with increasing glycerol content,which is accompanied by significant depression in the glass transition temperature and improvement in the extensibility of the biocomposites.

Study of the Thermal, Rheological, Morphological and Mechanical Properties of Biocomposites Based on Rod-Of Typha/HDPE Made up of Typha Stem and HDPE

The thermal, rheological and morphological properties of composite biomaterials made with mixture of high density polyethylene and typha rod powder (RD) were evaluated. The dynamic mechanical behavior of the samples was studied with 25%, 35% and 45% typha stem powder concentrations. The viscoelastic properties are mainly related to the nature of the polymer and the typha stem powder. Storage (G') and loss (G') moduli increased significantly, depending on the amount of powder in the molten mixture. After a viscosity increase was noticed in low frequency, it decreased in high frequencies, which demonstrates the pseudo-plasticity effect. Morphological and thermal characterization results have shown the dispersion state of the powder and its ability to modify the kinetics crystallization of biocomposites.

Preparation and Characterization of Raw and Chemically Modified Sponge-Gourd Fiber Reinforced Polylactic Acid Biocomposites

This research work has been undertaken to fabricate environmentally friendly biocomposites for biomedical and household applications. Sponge-gourd fibers (SGF) obtained from Luffa cylindrica plant were chemically treated separately using 5 and 10 wt% NaOH, acetic anhydride and benzoyl chloride solutions. SGF reinforced polylactic acid (PLA) biocomposites were fabricated using melt compounding technique. Surface morphological, structural, mechanical and thermal properties, as well as antibacterial activities of raw and chemically modified SGF reinforced PLA (SGF-PLA) composites were characterized by field emission scanning electron microscopy, Fourier transform infrared spectrometry, X-ray diffractometry, universal testing method, thermogravimetry, and Kirby-Bauer agar diffusion method, respectively. Surface morphology indicates that after treatment of fibers, the interfacial adhesion between PLA and fibers is improved. X-ray diffractometry result shows that chemical treatment of fibers improves the crystallinity and exhibits new chemical bond formation in the composites. After chemical treatment, compressive strength of the composites is found to increase by 10% - 35%. The thermal stability of the treated fiber reinforced composites is also found to increase significantly. The composites have no antibacterial activities and no cytotoxic effect on non-cancer cell line. Soil burial test has confirmed that the composites are biodegradable. Benzoyl chloride treatment of fibers shows superior mechanical properties and enhances thermal stability among the composites.

Chitosan/Nanocrystalline Cellulose Biocomposites Based on Date Palm (Phoenix Dactylifera L.) Sheath Fibers

In this study,nanocrystalline celluloses were used to enhance physical,mechanical and water vapor barrier properties of chitosan films for potential food packaging applications.Two different mineral acids(sulfuric and phosphoric)were used to extract nanocrystalline cellulose from date palm sheath fibers.The influence of cellulose I and cellulose II on the properties of the isolated nanocrystalline celluloses(e.g.,yield,energy and length of intra-and intermolecular hydrogen bonds,and degree of substitution)were studied too.The characteristics of chitosan biocomposite film with phosphorylated nanocrystalline cellulose were compared to those with sulfated nanocrystalline cellulose.Results showed that besides cellulose polymorphism,the ionic ester groups on the surface of nanocrystalline cellulose is one of the factors influencing the physical,chemical,mechanical,and water vapor barrier properties in chitosan/nanocrystalline cellulose biocomposites.

Experimental research on combustion fluorine retention using calcium-based sorbets during coal combustion(Ⅱ)

During the fixed bed tube furnace combustion experimental study,stimulated the calcium-based sorbent grain size and microstructured influencing factors to explain the fluorine retention effect influence law,and expounded the combustion fluorine retention agent developing principle,and probed into the high-temperature fluorine retention agent technical approach.The results show that the calcium-based sorbent particle grain size and pore structure also have the bigger influence on the combustion fluorine retention ef- fect,and reducing the calcium-based sorbent particle grain size and improving the calcium sorbent structure characteristics at very high temperature to enhance the fluorine retention effect is the important approach to the fluorine retention agent development.

Reactive Compatibilization of Short-Fiber Reinforced Poly(lactic acid)Biocomposites

Poor interfacial adhesion between biobased thermoplastics and natural fibers is recognized as a major drawback for biocomposites.To be applicable for the large-scale production,a simple method to handle is of importance.This work presented poly(lactic acid)(PLA)reinforced with short-fiber and three reactive agents including anhydride and epoxide groups were selected as compatibilizers.Biocomposites were prepared by one-step meltmixing methods.The influence of reactive agents on mechanical,dynamic mechanical properties and morphology of PLA biocomposites were investigated.Tensile strength and storage modulus of PLA biocomposites incorporated with epoxide-based reactive agent was increased 13.9%and 37.4%compared to non-compatibilized PLA biocomposite,which was higher than adding anhydride-based reactive agent.SEM micrographs and Molau test exhibited an improvement of interfacial fiber-matrix adhesion in the PLA biocomposites incorporated with epoxide-based reactive agent.FTIR revealed the chemical reaction between the fiber and PLA with the presence of epoxide-based reactive agents.

Hybrid Method for the Formation of Biocomposites on the Surface of Stainless Steel Implants

This study reports a hybrid method which allows the formation of biocomposites on stainless steel implants. The main idea of the method is to create multilayer coatings consisting of titanium primer layer and a microarc calcium-phosphate coating. The titanium layer is deposited from plasma of continuous vacuum-arc discharge, and calcium-phosphate coating is formed by the microarc oxidation technique. The purpose of the hybrid method is to combine the properties of good strength stainless steel with high bioactivity of calcium-phosphate coating. This paper describes the chemical composition, morphology characteristics, adhesion and the ability of the formed biocomposites to stimulate the processes of osteoinduction. It is expedient to use such biocomposites for implants which carry heavy loads and are intended for long-term use, e.g. total knee endoprosthesis.

Experimental research on combustion fluorine retention using calcium-based sorbets during coal combustion(Ⅰ)

In order to provide experimental guide to commercial use of fluorine pollution control during coal combustion, with fluorine pollution control during coal combustion in mind, this paper proposed the theory of combustion fluorine retention technology. Feasibility of fluorine retention reaction with calcium-based fluorine retention agent was analyzed through thermo-dynamic calculation during coal combustion. By simulating the restraining and retention effects and influential factors of calcium-based sorbets on vaporized fluoride during experimental combustion using fixed bed tube furnace, the paper systematically explored the influential law of such factors as combustion temperature, retention time, and added quantities of calcium-based sorbets on effects of fluorine retention. The research result shows that adding calcium-based fluorine retention agent in coal combustion has double effects of fluorine retention and sulfur retention, it lays an experimental foundation for commercial test of combustion fluorine retention.

Microstructure and phase composition of Ti-based biocomposites with different contents of nano-hydroxyapatite

Nano-hydroxyapatite(nHA) and titanium(Ti) powders with different ratios were prepared by mechanical ball milling,and then sintered in vacuum environment. The microstructure and phase composition of Ti-based biocomposites with different contents of nHA(5% and 10%,in volume fraction) were investigated. Meanwhile,the phase composition of pure Ti was studied for contrast. The results show that Ti phase forms a finer continuous network microstructure with few porous after milling and sintering. The higher amount of nHA powders are added,the higher amount of porous are achieved,while the fracture morphology becomes coarser. The specimen with contents of 10% nHA has serious interface reaction after sintering at 1 100 ℃,it varies with the pure Ti specimen. Combined with the XRD and EDS analysis,it can be founded that elements Ca,P,O and Ti diffuse on the interface,and the phases of Ti,Ti2O,Ti5P3,CaTiO3 and TiOx can be ascertained in nHA/Ti composites.

High-temperature H_2S Removal with Calcium-based Sorbent

The H2S removal characteristics of Taxada lime tinder the high temperature of 600-900℃ have been investigated. The test results indicated that this kind of sorbent almost was inert to H2S When temperature lowered down to 600℃,while its reactivity increased with increased temperature and the equilibrium conversion reached up to over 60% at temperatLlre of 900℃.However, side reactions of H2S in conjunction with high-temperature decomposition and mineral catalysis to elemental sulfur and sulfur dioxide were testified.

The Effect of Uncaria gambir on Optical Properties and Thermal Stability of CNF/PVA Biocomposite Films

Cellulose-based film has gained popularity as an alternative to synthetic polymers due to its outstanding properties.Among all types of cellulose materials available,cellulose nanofiber(CNF)has great potential to be utilized in a diverse range of applications,including as a film material.In this study,CNF biocomposite film was prepared by using polyvinyl alcohol(PVA)as a matrix and Uncaria gambir extract as a filler.This study aims to investigate the effect of Uncaria gambir extract on the optical properties and thermal stability of the produced film.The formation of the CNF biocomposite films was confirmed using Fourier Transform Infrared Spectroscopy,their transmittance characteristics were measured using UV-Vis spectroscopy and a transmittance meter,while their reflectance was determined using a reflectance meter.The results revealed that the addition of Uncaria gambir extract to the CNF biocomposite film improved its UV-shielding properties,as indicated by the lower percentage of transmittance in the visible region,10%–70%.In addition,its reflectance increased to 10.6%compared to the CNF film without the addition of Uncaria gambir extract.Furthermore,the thermal stability of the CNF biocomposite film with the addition of Uncaria gambir extract improved to around 400℃–500℃.In conclusion,the results showed that CNF biocomposite film prepared by adding Uncaria gambir extract can be a promising candidate for optical and thermal management materials.