Amorphous Constituents Research Articles

Lignocellulose sustainable composites from agro-waste Asparagus bean stem fiber for polymer casting applications: Effect of fiber treatment

In the past decades, lignocellulose fibers have attracted significant attention due to their low density, environmental friendliness, and biodegradability. Consequently, researchers are intensifying their efforts to explore the potential of lignocellulosic fibers as sustainable alternatives to synthetic fibers in polymer composites. Among various natural fibers identified as potential reinforcements, agro-waste from the Asparagus Bean stem (ABS) which has been discarded as landfill after harvest has emerged as a promising source of lignocellulose fibers for promoting sustainability. This study investigates the reinforcement suitability of ABSF in polymer matrices. A water-retting process was used for extraction, followed by treatment with a 5 % alkali solution. Cellulose content was enhanced to 65 wt%, and fiber density increased to 1.13 g/cm3 after chemical treatment. Thermogravimetric analysis indicated improved thermal stability of the treated fibers up to 247 °C. Morphological analysis showed increased surface roughness and impurity removal. To evaluate the reinforcing effect of the chemical treatment, epoxy composites with 10 wt% reinforcement were developed. The mechanical properties of these composites improved significantly, with more than 1.1 times when used alkali-treated ABSF as reinforcement. Flexural properties were substantially enhanced, with flexural strength increasing from 90.53 MPa to 122.71 MPa and flexural modulus from 2.41 GPa to 2.95 GPa due to better fiber-matrix interaction and removal of weak, amorphous constituents. The primary objective of this study is to demonstrate that ABSF is a viable alternative raw material for composite reinforcement, suitable for developing lightweight structural applications.

Study and Characterization of Algerian Spart Cellulosic Fibers (Lygeum spartum): Effect of Alkali and Acid Treatments on Their Physicochemical and Morphological Properties for Papermaking

Recently, non-wood plants have increasingly gained attention, due to their versatile advantages like cost and fast-growing period. The purpose of this study was to examine the effectiveness of different treatments on Algerian Spart fibers (Lygeum spartum) using sodium hydroxide at various concentrations (8, 10, 15, and 22% NaOH), and sulfuric acid at 30% for 2h at 100 °C. Fourier infrared spectroscopy (FTIR), X-ray diffraction (XRD), and scanning electron microscopy (SEM) analyses were used to characterize the microstructural changes in the treated fibers. The results of FTIR confirmed the presence of cellulose in the raw fibers with a crystallinity index of 49.4%. The FTIR and XRD studies showed that an 8% NaOH treatment eliminated the amorphous constituents and improved the crystallinity index. Also, SEM micrographs confirmed the removal of impurities; for the acid treated fibers a pseudo-lignin was formed and deposited on fibers surfaces in the form of spherical droplets. Moreover, a decrease in the yield of cellulose at high alkali concentrations was noticed. The results suggest the possibility of exploitation of Spart fibers and their application in papermaking and as a reinforcement in composite materials.

Silicon extraction from x-ray amorphous soil constituents: a method comparison of alkaline extracting agents

The growing interest in amorphous silica (ASi) within the fields of soil science and ecology underscores the necessity for a reliable protocol to estimate ASi contents in soil. Alkaline wet chemical extraction methods are commonly employed for silicon (Si) extraction from operationally defined (x-ray) amorphous Si phases or short-range ordered mineral phases in soils and marine sediments. In our study we conducted a comparative analysis of four alkaline extraction methods (1% sodium carbonate, 0.5 M sodium carbonate, 0.2 M sodium hydroxide, and 0.1 M Tiron), assessing their extraction selectivity as well as effectiveness using soils artificially enriched with varying, defined amounts of ASi. While extraction effectiveness was evaluated by determining the recovery rate of initially added ASi, extraction selectivity was determined by measuring aluminum (Al) and iron (Fe) concentrations as indicators of the dissolution of non-target mineral phases. Microwave plasma atom emission spectrometry was used to analyze Al, Fe, and Si concentrations in the extracts. Our results indicate that extraction with 0.2 M sodium hydroxide yields the best outcomes in terms of both extraction effectiveness and selectivity. This more recent extraction technique is conducted at the most alkaline pH (13.3) of all four methods tested, but at ambient temperature (21°C) decreasing the dissolution of non-target mineral phases. Though, no wet-chemical extraction used on heterogeneous samples like soil is precisely selective, and thus able to quantify the target analyte only. Hence, data obtained by such procedures still need to be interpreted with caution considering all their limitations.

A Fresh Perspective on the Impact of ZnTiO3 Coupling on the Microstructure and Photocatalytic Properties of TiO2 Fabricated at Varied Temperatures.

ZnTiO3/TiO2 composite photocatalysts were synthesized via the sol-gel technique, and the impact of varying heat treatment temperatures (470, 570, 670 °C) on their crystalline arrangement, surface morphology, elemental composition, chemical state, specific surface area, optical characteristics, and photocatalytic efficacy was systematically investigated. The outcomes revealed that, as the temperature ascends, pure TiO2 undergoes a transition from anatase to rutile, ultimately forming a hybrid crystal structure at 670 °C. The incorporation of ZnTiO3 engenders a reduction in the TiO2 grain dimensions and retards the anatase-to-rutile phase transition. Consequently, the specimens manifest a composite constitution of anatase and ZnTiO3. In contrast, for pure TiO2, the specimen subjected to 670 °C annealing demonstrates superior photocatalytic performance due to its amalgamated crystal arrangement. The degradation efficacy of methylene blue (MB) aqueous solution attains 91% within a 60-min interval, with a calculated first-order reaction rate constant of 0.039 min-1. Interestingly, the ZnTiO3/TiO2 composite photocatalysts exhibit diminished photocatalytic activity in comparison to pristine TiO2 across all three temperature variations. Elucidation of the photocatalytic mechanism underscores that ZnTiO3 coupling augments the generation of photogenerated charge carriers. Nonetheless, concurrently, it undermines the crystalline integrity of the composite, yielding an excess of amorphous constituents that impede the mobility of photoinduced carriers. This dual effect also fosters escalated recombination of photogenerated charges, culminating in diminished quantum efficiency and reduced photocatalytic performance.

Influence of fiber orientation on the moisture adsorption of continuous bamboo fiber composites

Recently, a considerable interest is being shown in the use of plant fibers as reinforcement for polymer composites. Indeed, researchers and scientists are trying to overcome the environmental bias by using bio-composites in several engineering applications. Their attractive specific mechanical properties, low cost, lightness and biodegradability may promote them to substitute expensive and non-renewable fibers such as carbon, kevlar and glass fibers. However, the hydrophilic behavior of natural fibers is of a great concern for their possible outdoor applications. Indeed, the entrapment of water molecules at the fiber lumen, voids and porosities may reduce the tensile strength and modulus of plant fiber composites. Hence, this work aims to evaluate the moisture adsorption behavior of bamboo fiber epoxy composites at different fiber orientations (tangential and radial directions). Firstly, bamboo fibers are extracted using a combination of compression and manual techniques. Morphological and thermogravimetric analyses are carried out to deeply understand the physical properties of the extracted fibers. The findings show that the fibers consist of parallel microfibrils enclosed by some impurities and amorphous constituents. The moisture content of bamboo fibers at 50RH% is deduced from the moisture evaporation stage in the thermogravimetric curve and is about 8.07%. Thereafter, hand layup and compression techniques are used to manufacture the composite samples for the moisture adsorption test. The obtained results show that the equilibrium moisture capacity and diffusion rate values are higher along the fiber direction, which is mainly due to the exposure of the fiber lumen and interfacial voids. The mechanism of moisture transport into composites is found to follow Fick’s law.

Comparison between alternative chemical treatments on coir fibers for application in cementitious materials

Agricultural production generates several residues, for example, oilseed residues (cotton, soy, sunflower, and palm oil) and fruit residues (coconut, pineapple, and cashew). Research shows several agents for the surface treatment of natural fibers, such as using alkalis in different proportions and exposure times. The chemical treatment removes surface impurities like wax, oils, fats, and insoluble compounds. However, few studies investigate the effect of chemical treatment type on coir fibers' physical-mechanical and microstructural properties. In this context, the present work aims to evaluate the impact of three chemical treatments: sodium hydroxide, oxalic acid with a concentration of 5 (wt. %) (1 and 2 h), and sodium bicarbonate 10 (wt. %) (120 and 168 h) in coir fibers. This study investigated the contents of extractives, lignin, hemicellulose and cellulose contents, mechanical properties, Fourier transform infrared spectroscopy, contact angle test, atomic force microscopy, scanning electron microscopy, X-ray diffraction, and thermogravimetric analysis. Besides, the FTIR test showed the removal partial of the amorphous constituents. The best results obtained by the treatment content of oxalic acid for 1 h promote a removal partial of extractives, lignin, and hemicellulose content. In addition, tensile strength increased by 22.9% compared to the untreated fibers. The increase in fiber roughness due to the chemical treatments promote better interaction with the cement paste and can reinforce cementitious materials.

Chemical extraction of cellulose from Ligno-cellulosic Astragalus armatus pods: Characterization, and application to the biosorption of methylene blue

The most widely available substrate, cellulose biopolymer, was shown to be used for several interesting applications such as pharmaceutical, composites, water treatment, textiles, etc. In this study, cellulose was chemically extracted from abundant Astragalus armatus pods through alkali and bleaching processes. The untreated biomass and the extracted polymer were characterized using FT-IR, XRD, SEM, and TGA-DTA analyses. FT-IR spectrum of the extracted cellulose confirmed that lignin and hemicellulose constituents were removed during alkali and bleaching treatments. The crystallinity index calculated for the extracted cellulose and the untreated Astragalus armatus pods were 38.2% and 25%, respectively. These small values proved the existence of the amorphous constituents in the composition of Astragalus armatus. The high crystallinity index calculated for the extracted cellulose confirmed the elimination of the amorphous constituents present in the untreated biomaterial. The change in the thermal decomposition indicated that the extracted cellulose was more thermally stable than the untreated biomass. At optimum conditions (T = 20 °C, pH = 6, and t = 60 min), the adsorption quantities were 165 mg/g and 148 mg/g of for untreated Astragalus armatus pods, and extracted cellulose, respectively. The adsorption mechanism was non spontaneous and the interaction between the studied biomaterials and methylene blue was exothermic. Overall, the adsorption results demonstrated that the untreated Astragalus armatus pods and the extracted cellulose were excellent candidates for color uptake from water.

Microstructure and mechanical performance of alkali-activated tuff-based binders

The production of coarse-grained aggregates and sands from tuff, a naturally occurring rock composed of primarily fine volcanic detritus, usually generates 20 wt% powder as a solid waste. This paper presents the attempt to synthesize two high-performance, low carbon footprint, binders using fine tuff powder: a tuff-based binder (TBB) and a tuff and ground granulated blast-furnace slag (GGBS)-based binder (T-GGBS). The maximum compressive strength, flexural strength, Young's modulus, and density of the NaOH and Na-silicate activated TBB cured at 60 °C for 28 days are 71.3, 17.0, 2100 MPa, and 1892 kg/m3 respectively, while those for the T-GGBS are 73.3, 15.8, and 1980 MPa, and 1880 kg/m3. To reveal the mechanisms for their high performance, an array of microstructure characterizations were performed on both the raw materials and final binders. For the TBB, the surfaces of irregular angular crystalline constituents in the tuff powder are partially dissolved and activated, while the undissolved part plays a key role as skeletons, as evidenced by the decrease of crystalline phases but increase in the N-A-S-H with increasing the NaOH concentration. For the T-GGBS, the amorphous GGBS constituents are fully dissolved and hence change the main product from the N-A-S-H gel to N/C-A-S-H cross-linked gel etc. However, overdosage of the GGBS consumes the majority of NaOH but leaves little to the reaction of tuff particles, most of which hence just act as inert fillers rather than reactants in the final binders. The effects of porosity on the mechanical performance are also discussed with reference to conventional geopolymers.

MECHANICAL BEHAVIOUR OF INFLORESCENCE/GLASS-FIBRE-REINFORCED HYBRID EPOXY COMPOSITES

The biodegradability and environmental friendliness of natural fibres makes them suitable for implementation in a circular economy. As a result, several natural fibres and processing methods have evolved. The hydrophilic nature of ligno cellulose fibrils restricts the effective adhesion at the interface of fibre and matrix. The hybridization of natural fibres with synthetic fibres leads to promising characteristics of the resulting composite materials. This paper deals with the hybridization of conventional glass fibre and natural fibre extracted from coconut inflorescence. The effect of hybridization on the tensile and flexural strengths of surface-modified inflorescence fibre with glass fibres was investigated. The composites were fabricated using a hand-layup technique by varying the inflorescence fibre and glass-fibre reinforcement composition by (5, 10, 15 and 20) %. A notable improvement in the tensile and flexural strengths of 193.65 MPa and 240.69 MPa was observed for 85 % of glass and 15 % of benzoyl-chloride-modified inflorescence-fibre-reinforced hybrid composites. The elimination of amorphous constituents in the inflorescence fibres was checked by XRD and FTIR analyses. A surface-morphology analysis of unmodified and benzoyl-chloride-modified inflorescence fibres revealed pores and cavity formation on the fibril walls. These composites with superior mechanical properties can be an alternative to synthetic fibre composites and ensure the implementation of a circular economy and sustainable manufacturing.

Fabricating polymer/HEA-hybrid topological lattice structure for enhanced mechanical properties

Metamaterials such as architected lattice structures have aroused broad interest in being applied as mechanical supports for their lightweight and custom-shaped capabilities. Although various prior efforts have been devoted, a multiscale fabrication of micro-nano lattice structures without penalizing the mechanical properties is still a challenging but highly desirable task. Here we put forward a strategy to produce a mechanically enhanced micro-nano lattice structure by conformally depositing a CoCrFeNiTi high-entropy alloy (HEA) coating layer onto a three-dimensional (3D) printed polymer skeleton. The template for the 3D printing employs a six-membered tricapped trigonal prism (6M-TTP) structure derived from a medium-range order structure motif in amorphous alloys. The topological complexity of the 6M-TTP can substantially avoid the stress concentration by offering stress-release channels, while the HEA film incorporating with amorphous and nanocrystalline constituents can further reinforce the lattice architecture through its size hardening effect. Benefitting from the above, the fabricated polymer/HEA-hybrid lattice exhibits a high specific compressive strength (∼0.055 ​MPa ​kg-1 m3 at a density below 500 ​kg ​m-3), a superior elastic recoverability (∼70% recovery rate under >30% compression), an enhanced plasticity (40% strain) and a high specific modulus (0.135 ​MPa ​kg-1 m3). Our strategy initiates a perspective way to fabricate multiscale micro-nano lattice structures with improved mechanical properties, which could be extended to widespread metamaterial research.

Role of Inorganic Amorphous Constituents in Highly Mineralized Biomaterials and Their Imitations.

A highly mineralized biomaterial is one kind of biomaterial that usually possesses a high content of crystal minerals and hierarchical microstructure, exhibiting excellent mechanical properties to support the living body. Recent studies have revealed the presence of inorganic amorphous constituents (IAC) either during the biomineralization process or in some mature bodies, which heavily affects the formation and performance of highly mineralized biomaterials. These results are surprising given the preceding intensive research into the microstructure design of these materials. Herein, we highlight the role of IAC in highly mineralized biomaterials. We focused on summarizing works demonstrating the presence or phase transformation of IAC and discussed in detail how IAC affects the formation and performance of highly mineralized biomaterials. Furthermore, we described some imitations of highly mineralized biomaterials that use IAC as the synthetic precursor or final strengthening phase. Finally, we briefly summarized the role of IAC in biomaterials and provided an outlook on the challenges and opportunities for future IAC and IAC-containing bioinspired materials researches.

Influence of Alkali Treatment on Physicochemical, Thermal and Mechanical Properties of Hibiscus Vitifolius Fibers

ABSTRACT Hibiscus vitifolius was found to possess the promising potential required for reinforcing polymer matrices. In this study, Hibiscus vitifolius fibers were immersed in 2, 3, 4, 5, 6, 7, and 8% NaOH solution for 1 hr and the effects of alkali treatment on chemical, mechanical and thermal characteristics of the fiber were evaluated through chemical tests, X-ray diffraction, Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis, tensile tests, and field emission scanning electron microscopy. From the test results, it was inferred that Hibiscus vitifolius fibers treated using 5% NaOH exhibited high crystallinity, tensile strength, and Young’s modulus compared to raw fibers. Beyond 5% NaOH treatment, the fibers suffered a decline in crystallinity index and mechanical properties. The morphological analysis of alkali-treated fibers revealed the removal of amorphous constituents and separation of fiber bundles into individual fiber filaments.

A damage-tolerant, dual-scale, single-crystalline microlattice in the knobby starfish, Protoreaster nodosus

Cellular solids (e.g., foams and honeycombs) are widely found in natural and engineering systems because of their high mechanical efficiency and tailorable properties. While these materials are often based on polycrystalline or amorphous constituents, here we report an unusual dual-scale, single-crystalline microlattice found in the biomineralized skeleton of the knobby starfish, Protoreaster nodosus. This structure has a diamond-triply periodic minimal surface geometry (lattice constant, approximately 30 micrometers), the [111] direction of which is aligned with the c-axis of the constituent calcite at the atomic scale. This dual-scale crystallographically coaligned microlattice, which exhibits lattice-level structural gradients and dislocations, combined with the atomic-level conchoidal fracture behavior of biogenic calcite, substantially enhances the damage tolerance of this hierarchical biological microlattice, thus providing important insights for designing synthetic architected cellular solids.

A comparative study on the comminution behavior of diorite rocks

In this article factors that affect the comminution behavior of heterogeneous diorite rocks obtained from two quarry locations in Botswana were investigated. Diorite rocks are in great abundance in Botswana and they are increasingly viewed as a relatively inexpensive and reliable alternative construction material to sustain the infrastructure growth in Botswana. The diorite rock samples collected from both the Central and North-Eastern districts were studied for structural similarities and mineral composition. These two are the main factors that influence material hardness, fracture toughness and particle size distribution (PSD) following breakage, which are important material properties in construction applications (Barry & James, 2016). The aim of the investigation was to comminute and compare the behavior of the rock sample types, under similar experimental conditions in a laboratory jaw crusher as well as in a planetary ball mill. The product PSD was used to theoretically determine and compare power requirements. The experimental results show that the diorite rock sample collected from the central region required 41.58 KWht-1 while the one collected from the north-eastern region required 38.33KWht-1 to fragment from a particle feed in the -50 + 40 mm size range to a product in the -11.2 + 6.3 mm size range, which is a typical construction aggregate size range. The diorite sample collected from the central district was largely characterized by amorphous phase constituents and high silicate/quartz content (12.4%) while the north-eastern diorite was characterized by a high crystalline phase percentage and lower silicate/quartz composition (6.94%). The experimental results show that inherent diorite rock properties play a significant role in determining cost of production and product application in the quarry industry of Botswana.

Bioactive glass with biocompatible polymers for bone applications

Conventionally, to permeate and repair bone defects, bioactive glasses have been used. Currently, this group of bio-materials has become a rising study for bone tissue engineering applications. 45S5 Bio glass of Larry Hench was the prime artificial material developed to generate a chemical connection with the bone, introducing the domain of bioactive ceramics. Bioactive glass is exceptionally biocompatible and can constitute a HA coat when rooted in the physique. Several characteristics of bioactive glasses, including sterile characteristics, can be nurture by accumulating a variety of biocompatible polymers into the glass. This study aims to review the modern and upgrade evolution of glass for bone regeneration. For bioactive glass containing biocompatible polymers, various synthesized techniques have been developed, including electrospinning, fabrication process, sol–gel process, ultrasonic power, magnetic stirrer, solvent casting technique, and microscopic technique. The materials for bone repair are such as Zein, 58S, Tri-Calcium Phosphate, and Zirconia. Bio-glasses are amorphous silicate-based constituents that connect to osseous matter and can restore newfangled bone progress while dissolving concluded period. As a result, they may restore the ailing or defective bone to its former condition and purpose (osteogenesis).

Slaked Lime Solution as a Viable Eco-friendly Treatment to Improve the Tensile Strength of Maize Stem Fibers

ABSTRACT In this study, the effect of the environmentally friendly slaked lime solution on the tensile strength of maize stem fibers was investigated and compared with the tensile strength obtained with a 3% wt NaOH and 10% wt NaHCO3 solutions. Maize fibers from dried stems were manually extracted, cleaned, and treated with the respective three solutions at different soaking periods. The results showed that a maximum increase in tensile strength of 165.1% was obtained with the NaOH treatment (at 24 hours) followed by an increase of 107.1% (at 21 hours) for the Ca(OH)2, and a 46.6% (at 18 hours) increase for the NaHCO3 treatment. Analysis of the FTIR spectra revealed that the significant improvement in the tensile strength for the NaOH treatment is attributed to the partial transformation of cellulose I to cellulose II. However, the increase in the strength of the Ca(OH)2-treated fibers has been attributed first, to the significant reduction in the fiber cross-sectional area, second, to the removal of specific amorphous constituents such as hemicellulose, and to the formation of a stable calcium pectinate layer, which improves the fiber’s resistance to fracture.

Phosphate sorption‐desorption properties in volcanic topsoils along a chronosequence and a climatic gradient on the Galápagos Islands

AbstractBackgroundPhosphorus (P) retention behavior in the soil is one of the main factors driving ecosystem productivity and changes strongly during soil weathering. Volcanic soils are known for their high phosphate (PO4) sorption capacity (PSC). However, the changes of PO4 buffering properties and fixation processes in the course of their pedogenic development are not fully understood.AimWe investigated the short‐term and longer‐term PO4 sorption‐desorption behavior in volcanic topsoils from the Galápagos Islands along a precipitation gradient (elevation sequence, 47–866 m asl) and a soil age gradient (chronosequence, 1.45–1070 ka) under humid climate.MethodsLabile P (Mehlich‐3, resin‐P), P desorption (resin‐desorbable P after 1 and 6 months incubation), PSC (sorption isotherms, equilibration time = 72 h) and sorption kinetics (4 h–62 days) were analyzed and compared against a broad range of topsoil parameters.ResultsSoils developed very high PSC within 4.3 ka of soil weathering (Langmuir Qmax = 18.2 g P kg–1) due to the development of amorphous soil constituents. As the colloidal fraction changed to 2:1‐type crystalline clays after 26 ka of soil weathering under humid climate, PSC declined rapidly, while labile P and resin‐desorbable P reached a maximum. In older topsoils (≥ 165 ka), acidification and prevalence of aluminium (Al) and iron (Fe) (hydr)oxides led to increased P sorption again. Along the elevation sequence, increased precipitation favored the formation of amorphous constituents, resulting in a steep increase of P sorption capacity (from 0.9 to 19.9 g P kg–1) from the arid lowlands to the very humid highlands.ConclusionAmorphous Fe and Al phases as well as Fe and Al bound to organic matter seemed to be the main driving factors for P sorption along the studied pedogenic gradients.

Phase development in RbInSe2 thin films – a temperature series

Rb, In and Se were deposited in a co-evaporation chamber at various substrate temperatures (TSub = 280°C, 350°C, 450°C, 550°C) on Mo coated soda-lime glass. It was found that the RbInSe2 crystal phase is already detectable for nominal TSub = 350°C. During calibrated in-situ high-temperature grazing incidence X-ray diffraction on the sample grown at the lowest temperature, crystallization of monoclinic RbInSe2 can be observed at 215°C ± 3°C. The morphology of the layers shows distinct differences for increasing TSub, while the elemental composition of the deposited thin films only exhibits minor changes. The deposited layers show a decrease of (X-ray) amorphous constituents and changes in the preferred crystal orientation of the RISe layer with increasing TSub. The influence of Na supply on the layer growth was investigated by applying a SiNxOy diffusion barrier layer in between the glass substrate and the Mo layer on half of the studied samples.

Extraction and Characterization Studies of Cellulose Derived from the Roots of Acalypha Indica L

ABSTRACT The underlying principle of this current research was to characterize the cellulosic fibers that were retted from the roots of Acalypha indica L. plant to find their aptness for making green composites. Physical characterization tests were conducted and reported proving the reinforcing capability of these fibers which has a density of 1.356 g/cm3. Chemical composition tests conducted on these fibers showed the weight % of cellulose as 67.86. Amorphous constituents such as hemicellulose and lignin were present as 0.24 and 18.75 weight %, respectively. Wax, ash, and moisture were respectively present as 0.86, 2.13, and 10.16 weight % of fibers. X-ray diffraction (XRD) studies purported the presence of both amorphous and crystalline contents of cellulose confirming the peaks of Fourier-transform infrared spectroscopy (FTIR) studies. The fibers possessed a crystallinity index of 46.62% and their crystallite size was computed as 3.68 nm from XRD, with a good temperature bearing capacity of 225°C as ascertained from the thermo-gravimetric analysis. Conglomeration of fibrils and the roughness characteristics were evident from the scanning electron microscopic images and atomic force microscopic observations, respectively. Thus, it can be seen that this newly identified fiber are apposite reinforcements and can be explored further by infusing them in polymer matrices for making sustainable products.

A Comparative Study on the Comminution Behavior of Diorite Rocks

In this article factors that affect the comminution behavior of heterogeneous diorite rocks obtained from two quarry locations in Botswana were investigated. Diorite rocks are in great abundance in Botswana, and they are increasingly viewed as a relatively inexpensive and reliable alternative construction material to sustain the infrastructural growth in Botswana. The diorite rock samples collected from both the Central and North-Eastern districts were studied for structural similarities and mineral composition. These two are the main factors that influence material hardness, fracture toughness and particle size distribution (PSD) following breakage, which are important materials properties in construction applications. To comminute and compare the behavior of the rock sample types, similar experimental conditions in a laboratory jaw crusher, cone crusher as well as in a planetary ball mill were employed. The product PSD was used to theoretically determine and compare power requirements. The experimental results show that the diorite rock sample collected from the central region required 41.58 KWht-1 while the one collected from the north-eastern region required 38.33KWht-1 to fragment from a particle feed in the -50 + 40 mm size range to a product in the -11.2 + 6.3 mm size range, which is a typical construction aggregate size range. The diorite sample collected from the central district was largely characterized by amorphous phase constituents and high silicate/ quartz content (12.4%) while the north-eastern diorite was characterized by a high crystalline phase percentage and lower silicate/ quartz composition (6.94%). The experimental results show that inherent diorite rock properties play a significant role in determining cost of production and product application in the quarry industry of Botswana.