Shell Content Research Articles

PREDICTING THE COMPRESSIVE STRENGTH OF PALM KERNEL SHELL CONCRETE USING FULL FACTORIAL EXPERIMENTAL DESIGN

Research has shown that the strength characteristics of Palm Kernel Shell Concrete (PKSC) are highly dependent on the mix parameters. This paper, through series of trial mixes, aim to achieve a model by which mix proportions can be selected for a target compressive strength using palm kernel shell as aggregate in concrete. This was done by testing the compressive strength of concrete containing varying total aggregate-cement content from ratio 3 to 6 in steps of 0.7 and water-cement ratios of 0.50, 0.55 and 0.60. The palm kernel shell content too was varied as a percentage replacement of coarse aggregate from 0 to 100% in steps of 10. From the trial mixes, the maximum, medium and minimum values of concrete mix variables were determined. A three-level three-factor full factorial design of experiments was used to investigate their effects. A total of 32 tests were carried out, including five control experiments (center points). A linear regression model was employed to model the measured compressive strength, this model predicts the compressive strength from a combination of water-cement ratio, palm kernel shell content and cement content. The model yielded a good prediction of compressive strength and provided good correlations with the data used in this study. The coefficient of determination, R-squared was 0.985, implying the model is highly reliable. Moreover, the proposed model proved to be valid in predicting the compressive strength of concretes whose mix parameters varied from the data used to develop the model.

Effect of alkali treatment on wear behaviour of walnut shell reinforced bio-composites

In this study, the tribological behaviour of composites reinforced with walnut shells (0 % to 10 % at 2 % interval) has been investigated. The pin-on-disc machine is used us to observe the impact of walnut shell addition on the wear properties of the composite. An increase in walnut shell content is associated with diminished wear resistance. Inadequate adhesion among the fibre and the matrix was also identified as the cause of this wear strength degradation in testing results. Pre-treatment of walnut shell with sodium hydroxide increases wear resistance by strengthening matrix adherence to fibre. Different normal loads (from 6 N to 48 N), sliding velocities of 100 cm/s, and sliding distances (SD) of 0 to 2000 m were all considered in the experiments. The findings revealed that operation settings and filler reinforcement have an important impact on the wear behaviour of composite containing walnut shell filler. In comparison to dry and hot contact, the specific wear rate (SWR) is nearly 7 to 8 times lesser in wet conditions. Additionally, equated to a composite with a higher filler loading, the performance of one with a lesser loading of walnut shell filler was superior in terms of wear.

Upcycling post-harvest biomass residues from native European Lupinus species: from straws and pod shells production to nutritive value and alkaloids content for ruminant animals.

The production of Lupinus seeds for food and feed is increasing worldwide, which results in large amounts of post-harvest biomass residues, considered of low value and left in the field to be burned or incorporated in the soil. To valorize these agricultural wastes, this work aimed to assess their potential as an alternative feed for ruminants. Thus, the production yield, nutritive value, and alkaloid content of straws and pod shells from three native European Lupinus species, L. albus 'Estoril' (white), L. angustifolius 'Tango' (narrow-leafed), and L. luteus 'Cardiga' (yellow), cultivated in two locations, were evaluated. The dry matter (DM) yield of straws and pod shells were the highest for L. albus 'Estoril' (4.10 t ha-1) and the lowest for L. angustifolius 'Tango' (1.78 t ha-1), suggesting a poor adaptation of narrow-leafed lupin to the particularly dry and warm agronomic year. Despite species-specific differences, lupin biomass residues presented higher crude protein (53.0-68.9 g kg-1 DM) and lignin (103-111 g kg-1 DM) content than cereal straws usually used in ruminant feeding, thus resulting in higher metabolizable energy (6.43-6.58 MJ kg-1 DM) content. In vitro digestibility was similar among lupin species (47.7-50.6%) and higher in pod shells (53.7%) than in straws (44.6%). Lupinus albus 'Estoril' and L. luteus 'Cardiga' presented considerable amounts of alkaloids in straws (23.9 and 119 mg kg-1 DM) and pod shells (20.5 and 298 mg kg-1 DM), while no alkaloids were detected in L. angustifolius 'Tango' biomass residues. Considering the combined production of straw and pod shells per lupin species, it is anticipated that lupin biomass residues produced per ha can fulfill 85% of the energy and nearly 50% of protein requirements of a flock of 4 to 9 dry and mid-pregnancy sheep with 50 kg body weight for one year. No negative effects on small (ovine) and large (bovine) ruminant species due to alkaloids are expected, even if biomass residues are consumed at up to 85% DM intake. The large production yield along with its nutritive value unveils the potential of lupin biomass residues valorization as alternative fodder for ruminants, promoting sustainability under a circular economy approach.

Lignin extraction and green-like lignocellulose biomass pyrolysis as an alternative sustainable biofuel

Cellulose, hemicellulose, and lignin make up the majority of biomass energy, which is a sustainable and renewable feedstock. Since lignin is the most common naturally occurring aromatic polymer on Earth, it holds great promise for useful products. Separating lignin from cellulose in biomass before converting it to biofuels or bioproducts is a crucial pre-treatment step. Alkali acid can be used to extract lignin from non-food components that remain following agricultural processing. As a result, we achieve the required lignin by the above procedure was used. The results demonstrate an extraction process of 5 hours, 4 hours, and 3 hours at 100 degrees Celsius, 130 degrees Celsius. Utilizing NaOH and H2SO4 for liquor and biomass to liquor ratio of 1:20. The total lignin content of the walnut shell was 13% lignin yield at 5 hr as well as neem tree bark biomass was found to be 5 % at 3 hours and walnut shell 14 % at 5 hr as well as 8% at 3 hours for almond shell lignin yield. It can be seen that the walnut shell produced the most lignin when compared to other types of biomass.

Effect of pyrolysis, impregnation, and calcination conditions on the physicochemical properties of TiO2/Biochar composites intended for photocatalytic applications

Biochars are outstanding materials obtained from the pyrolysis of biomass, possessing unique physicochemical properties that are attractive for many environmental applications, including photocatalysis. In this work, we have synthesized for the first time TiO2/Biochar composites using Aeroxide P25 TiO2 and biochars produced from the thermal treatment at low (or null) oxygen content of Colombian coconut shells. To explore and ultimately tune the final physicochemical properties of the TiO2/Biochars materials, a facile wet impregnation method was assessed, in which the following factors were evaluated: 1) Temperature and 2) %O2 in the pyrolysis of the biomass, 3) TiO2/Biochar ratio used in the impregnation and 4) Calcination temperature of the TiO2/Biochar composites. A comprehensive characterization of the novel composites was done, using techniques such as: XRD, XPS, BET, ATR-FTIR, diffuse reflectance, PL, SEM, and electrochemical analysis. The material synthesized with TPyrol = 350 °C, %O2 = 2.5, T/B = 0.8 and TCal of 800 °C presented notable properties such as low Eg, reduced recombination of e--h+ pairs, a high surface area, and a relatively high photogeneration of charges, and interestingly, it experienced phase transition from Anatase-Rutile to Anatase-Brookite. On the other hand, low TPyrol and high %O2 values conduct to hydrophilic functional groups on the TiO2/Biochar composites, whereas the use of higher TPyrol and TCal lead to a more hydrophobic character but promote the reduction of the recombination of photogenerated e--h+ pairs. As a result, this information is relevant for planning future applications of photocatalysis for degrading pollutants of different chemical nature.

Addition of Anadara Granosa Shell Chitosan in Production Bioplastics

Bioplastics is a plastic composite material that can decompose quickly and is environmentally friendly when interacting with soil and microorganisms. The aims of the research are: to examine the optimal composition of bioplastics made from tapioca waste by adding blood clam shell chitosan and glycerol, to determine the quality of production bioplastics from tapioca waste with the addition of blood clam shell chitosan and glycerol, and to determine the chemical content of the clam shells. bioplastic function of tapioca with the addition of blood clam shell chitosan and glycerol. The method used is experimental. Production of bioplastic by mixing waste tapioca flour, chitosan, and glycerol with a composition of 65%:35%:5mL, 70%:30%:5mL, and 75%:25%:5mL and additional water. The sample was put into a water bath and stirred at a temperature of 80oC for 15 minutes. Bioplastics were printed in aluminum foil, dried at 100oC for 90 minutes and cooled at room temperature for 6 hours. Laboratory test samples with tensile strength, elongation at break, FTIR, and biodegradation tests according to SNI 7188.7:2016 in the category of bioplastic easily decomposed. The results of the tensile strength on PBA1 samples were 0.75 Mpa, PBA2 samples were 0.54 Mpa, and PBA3 samples were 0.34 Mpa. Test value for elongation at break the PBA1 sample is 23.68%, the PBA2 sample is 15.33%, and the PBA3 sample is 12.12%. The sample test results do not meet the quality standard value of SNI 7188.7:2016 for the bioplastic category. The optimal composition of bioplastics is found in the PBA2 sample using tapioca flour as raw material with chitosan and glycerol as much as 70%:30%:5mL with a tensile strength 0.54%, an elongation at break 15.33%, biodegradation of 43%, and has a bioplastic content with functional groups (C=C), (CO), (CH),(OH), (C=C), and (CH2)n in the FTIR test results.

Development of self-healing sol-gel anticorrosion coating with pH-responsive 1H-benzotriazole-inbuilt zeolitic imidazolate framework decorated with silica shell

Zeolitic imidazolate framework-8 (ZIF-8)-based pH-responsive nanocontainers present a new pathway to endowing sol-gel anticorrosion coatings with self-healing ability. The organic nature of the ZIF-8-based nanocontainers, however, makes them less compatible with the inorganic sol-gel coating matrix, thus ineffective in protection against corrosion. In this paper, a novel pH-responsive corrosion inhibitor release system (BTA-ZIF-8@SiO2) based on ZIF-8 for self-healing sol-gel anticorrosion coating was reported. A facile one-step self-assembly procedure was used to create the 1H-benzotriazole (BTA)-encapsulated ZIF-8 core, on which a layer of silica was subsequently coated using a standard sol-gel method. The silica shell can provide better compatibility of the nanocontainers with the sol-gel matrix, thus improving the overall corrosion protection. Characterizations of the BTA-ZIF-8@SiO2 nanocontainers via X-ray diffraction spectroscopy, Fourier transform infrared spectroscopy, thermogravimetric analysis, Brunauer−Emmett−Teller, scanning electron microscopy/energy-dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy confirmed the successful synthesis of ZIF-8-based nanocontainers with high loading content of BTA and mesoporous SiO2 shell. Inhibitor release studies revealed the pH-responsive smart release of inbuilt BTA at both acidic and alkaline media. The anticorrosion performance of sol-gel coating incorporating the nanocontainers was investigated by electrochemical impedance spectroscopy, scanning Kelvin probe, and salt spray test, and the results indicated that BTA-ZIF-8@SiO2 could effectively enhance the corrosion protection properties of the coating and exhibit excellent self-healing performance, in which the |Z|0.01Hz was >2 orders of magnitude higher and coating resistance and oxide layer resistance were >3 orders of magnitude higher than these of pure sol-gel coating after 28 d of immersion. This could be attributed to the synergistic effect of enhanced passive protection, improved nanocontainer compatibility with the sol-gel matrix, and corrosion inhibitor film formed on metal surface.

Hydrothermal pretreatment based on biogas slurry recycling to improve methane yield of typical plant wastes from South China

Lignin content of feedstock contributed more for the biomass recalcitrance despite of the comprehensive effect from multiple physical and chemical characteristics based on the anaerobic digestion analysis of 16 plant wastes from South China. With the objective of improving anaerobic digestion performance of mixed fruit shell, hydrothermal pretreatment based on biogas slurry recycling (HPBSR) was proposed. Compared with traditional hydrothermal pretreatment, the lignin content of mixed fruit shell was reduced by 4.51–21.13% after HPBSR. The soluble chemical oxygen demand of liquid fraction under 200 ℃ increased by 87.45% relative to the control group with biogas slurry. And the cumulative methane yield of anaerobic digestion was 129.97 mL/gVS, which was 45.01% and 18.78% higher than the control group without treatment and the hydrothermal pretreatment group, respectively. Moreover, the HPBSR experimental group did not produce anaerobic digestion inhibitors (furfural and 5-hydroxymethylfurfural), and the higher humic acid concentration would be another possible reason for the improvement of methane yield. The related results will provide insights into the resource utilization of biogas slurry.

Handheld and benchtop vis/NIR spectrometer combined with PLS regression for fast prediction of cocoa shell in cocoa powder

The fermented and dried cocoa beans are peeled, either before or after the roasting process, as peeled nibs are used for chocolate production, and shell content in cocoa powders may result from economically motivated adulteration (EMA), cross-contamination or misfits in equipment in the peeling process. The performance of this process is carefully evaluated, as values above 5% (w/w) of cocoa shell can directly affect the sensory quality of cocoa products. In this study chemometric methods were applied to near-infrared (NIR) spectra from a handheld (900–1700 nm) and a benchtop (400–1700 nm) spectrometers to predict cocoa shell content in cocoa powders. A total of 132 binary mixtures of cocoa powders with cocoa shell were prepared at several proportions (0 to 10% w/w). Partial least squares regression (PLSR) was used to develop the calibration models and different spectral preprocessing were investigated to improve the predictive performance of the models. The ensemble Monte Carlo variable selection (EMCVS) method was used to select the most informative spectral variables. Based on the results obtained with both benchtop (R2P = 0.939, RMSEP = 0.687% and RPDP = 4.14) and handheld (R2P = 0.876, RMSEP = 1.04% and RPDP = 2.82) spectrometers, NIR spectroscopy combined with the EMCVS method proved to be a highly accurate and reliable tool for predicting cocoa shell in cocoa powder. Even with a lower predictive performance than the benchtop spectrometer, the handheld spectrometer has potential to specify whether the amount of cocoa shell present in cocoa powders is in accordance with the Codex Alimentarius specifications.

Manual Shelling of Preconditioned Cashew Nut Using Handtool and Its Impact on Occupational Health of Workers

India is the second-leading country in production of cashew nut. Cashew nut are roasted or steamed before shelling. The study was conducted in cashew nut processing industries situated in Selsella and Mankachar blocks of Meghalaya and Assam. The purpose of this study was to compare the cutting strength of cashew nut shells influenced by roasting and steaming. The impact of manual shelling of cashew nut on occupational health of workers was also assessed by using ergonomic tools. The moisture content, colour, and hardness of cashew nut shell were measured. The processing of cashew nut influenced the cutting strength of cashew nut significantly. Steamed cashew nut shell was stronger than the roasted cashew nut shell. Hence, manually shelling of steamed cashew nut shell required more force compared to with that of roasted cashew nut shell. Four cashew nut processing industries, two each from Selsella and Mankachar block of Meghalaya and Assam, respectively were selected purposively. A group of 10 female workers from each industry were selected randomly as sample for this study. Ergonomic parameters: working Heart Rate, energy expenditure, rated perceived exertion, hand grip measurements, RULA and REBA analysis were used to assess occupational health of workers. The results of the study showed that the workers of cashew nut industries were exposed to high occupational health and safety risk due to poor working environment, awkward working posture, repetitive and tedious job.

Aktivitas Antioksidan, Kadar Flavonoid, dan Fenolik Total Cangkang Kerang Mutiara (Pinctada maxima)

Antioxidant compounds are able to dampen or ward off free radicals. Living things including pearl mussels (Pinctada maxima) can produce secondary metabolite compounds (phenolics, alkaloids, and terpenoids). There have been no studies on the antioxidant potential, flavonoid content, and total phenolics of pearl clam shells. This study aimed to determine the antioxidant potential of pearl clam shell ethanol extract (EECKM) in vitro using the DPPH method. In addition, it aims to determine the total flavonoid and phenolic levels of EECKM. The powder of pearl mussel shells is soaked with ethanol and the filtrate is concentrated until a concentrated extract is obtained. Flavonoid and phenolic levels from EECKM were measured using a UV-Vis spectrophotometer. Measurement of antioxidant activity using the DPPH method. EECKM has a yield of 1.73%, flavonoid levels of 0 mg QE/g, and total phenolics of 4.8 mg GAE/g. The extract has the highest antioxidant activity for a concentration of 100 mg / L with a percent value of DPPH radical inhibition of 67.1%.

The Efficiency of Urtica dioica Extract in Feeding of Laying Hens

Currently, poultry specialists are working hard to find feed additives of natural origin. Medicinal plants are a source of a wide range of biologically active compounds with multifunctional effects, including antimicrobial ones. To understand the potential use of various medicinal plants and their extracts in poultry farming, the current study aimed to investigate the effect of feeding different doses of water-ethanol extract of Urtica dioica (Urtica dioica L.) on the egg productivity of laying hens. A total of 300 laying hens were divided to control and five experimental groups of chickens, each with 5 replicates. During the entire experiment, the laying hens of the control group were fed complete compound feeds according to the egg-laying phase, and the chickens of the experimental groups were additionally fed Urtica dioica extract in different doses. The results indicated that feeding laying hens with Urtica dioica extract in doses of 5, 10, 15, 20, and 25 mg/kg of body weight had a positive effect on their egg productivity. An increase in egg production per average laying hen in the experimental groups was 2.6-6.1%, and the intensity of egg production was 2.1-5.4%, compared to the control. However, the feed consumption in all experimental groups decreased. When introducing Urtica dioica extract into full-fledged compound feeds for laying hens, there was an increase in the relative egg white content, egg white/egg yolk ratio, and a decrease in relative yolk and shell content. Accordingly, it is suggested to include Urtica dioica extract at a dose of 15 mg/kg in the diet of laying hens which can improve economic efficiency and egg parameters. Keywords: Chemical composition, Egg morphology, Egg production, Feed conversion, Medicinal plant

Influencing Factors of the Brittleness of Continental Shales Containing Shell Limestone Interlayer

Brittleness is important in the evaluation of the fracturing ability of shale reservoir and has a significant impact on shale gas exploration and development. This paper discusses the characteristics and controlling factors of brittleness of continental shale in the Da’anzhai Member of the Ziliujing Formation of Lower Jurassic age in the northeast Sichuan Basin. Continental shale lithofacies and their associations were grouped into four main rock types: clayey shale, silty shale, shell calcareous clayey shale, and silty clayey shale, characterized by the high clay content and local enrichment of carbonate minerals as a whole. Compared with the marine shale, the continental shale contained a low content of siliceous minerals, a high content of carbonate minerals, and a large number of shell limestone interlayers. Carbonate minerals play an important role in controlling the brittleness of continental shale. The shale interlayers were mainly shell limestone interlayers with a thickness of several centimeters and a large number of shell laminates with thicknesses of several millimeters were also observed. The shell laminates were mainly filled with calcite. Due to the dissolution process, a large number of bedding joints and corrosion joints were formed in the calcite shell layers. In the interlayers with a high shell content, a large number of microfractures developed. The energy consumption required for maintaining fracture expansion was lower after fracturing; the fractures greatly improved the reservoir’s brittleness.

Valorization of Dredged Harbor Sediments through Lightweight Aggregate Production: Application of Waste Oyster Shells

The treatment and valorization of wastes such as dredged harbor sediments and oyster shells have become critical for environmental management. In order to promote waste valorization and resource sustainability, this study evaluated the feasibility of using harbor sediments and oyster shells for lightweight aggregate (LWA) production. The effects of the oyster shell content and sintering temperature on the sediment-based LWA properties, including particle density (PD), water absorption (WA), and crushing strength (CS), were investigated. The engineering applicability of the sediment-based LWAs was also assessed. The results showed that it was feasible to use harbor sediments admixed with oyster shells to produce LWAs that were suitable for engineering applications. The LWA properties were highly varied according to the sintering temperature and oyster shell content. Remarkably, the LWAs prepared with a 5–15% oyster shell content and sintered at 1125 °C were suitable for structural lightweight concrete (PD: 1.73–1.83 g/cm3, WA: 12.2–15.1%, CS: 7.2–10.4 MPa). The open porosity was a key factor affecting the particle density, water absorption, and crushing strength of the LWAs. Moreover, the leachability of toxic metals and chloride ions in the LWAs complied with the regulations for building materials in Taiwan. Waste oyster shells could be an excellent additive to lower the optimal sintering temperature required for sediment-based LWA production.

In situ coating of energetic crystals: A compact core-shell structure with highly reduced sensitivity

The weak interfacial interaction and high sensitivity is a longstanding problem for nitramine explosives. Herein, polyhydroxyethyl acrylate nitrate (PANE) was adopted to passivate three nitramine explosives through a facile and efficient in situ polymerization method. The core-shell structure of the PANE-coated composites was confirmed after detailed morphological and structural characterization. As a result, we find that, the hydrophobic PANE shell improved the adhesion work between the explosives and fluoropolymer (F2314) binder because of the enriched interfacial interactions. Besides, 2% PANE can retard the crystal transformation of CL-20 and HMX explosives by 10.7 °C and 4.3 °C, but does not affect the thermal decomposition behavior. The mechanical sensitivity of PANE-coated composites decreased more significantly than raw explosives and the mixed samples. As a typical example, the impact and friction sensitivity of CL-20@PANE composite with 2.0% shell content is practically halved when compared to raw CL-20 with the characteristicheight (H50) of 32.2 cm and the explosionprobability (P) of 50%. This study offers a simple, effective and universal method for design and preparation of energetic composites with high safety performance.

DEPENDENCE OF POLYURETHANE CONTENT ON PHYSICAL AND MECHANICAL PROPERTIES OF WOOD FIBER/PALM KERNEL SHELL COMPOSITES

Wood-based composites with different ratiosof wood fiber (WF)/palm kernel shell (PKS) and polyurethane (PU) content have been prepared using the wet-process method. Samples of WF85/PKS15 and WF75/PKS25 were fabricated where each sample was applied with 20% and 70% of PU contents and itsphysical and mechanical properties had beenstudied. The physical results show that the samples with 70% of PU content were denser, had low porosity, low moisture content,and low water absorption. Surface morphology observation shows both series samples with high PU content tend to form tube-like shape with different diameter. Inmechanical studies, generally, the sample with high PKS and PU possesseshigh flexural strength, flexural modulus, tensile strength, tensile modulus,and hardness. However, theincreased of PKS content in the composite reduces the tensile strength for both sampleswith 20% and 70% of PU. The effects of the binder and palm kernel shell in the composite were also explained. Based on the Japanese Industrial Standard (JIS) A 5905 standard, the sample composites meet therequirement under medium density fiberboard (MDF) category and classified as board type 5 which suitable as furniture, house,and automotive interior design and construction materials.

Preparation and characterization of lignin-containing cellulose nanocrystals from peanut shells using a deep eutectic solvent containing lignin-derived phenol

In this work, a method of preparing lignin-containing cellulose nanocrystals (LCNC) from agricultural waste peanut shells by ultrasonic-assisted deep eutectic solvents (DES) was studied. The peanut shells were pretreated with binary DES ChCl-GG (choline chloride: guaiacol, 1:1 molar ratio) and ternary DES ChCl-GG-AlCl3·6 H2O (choline chloride: guaiacol: aluminum trichloride hexahydrate, 1:1:0.01, 1:1:0.03, 1:1:0.05, and 1:1:0.07 molar ratios) at 120 ℃ for 3 h, and then subjected to mild mechanical decomposition. Under the optimal DES pretreatment conditions (the molar ratio of ternary DES is 1:1:0.07), the cellulose content of peanut shell reached the highest of 59.49% (36.39% without treatment), and the removal rates of lignin and hemicellulose were 73.22% and 93.05%, respectively. At the same time, LCNC obtained by this process shows good thermal stability (Tmax = 337 ℃) and has the potential for further applications. When the conditions were optimal, the length of LCNC was about 188.94 nm, the width was about 2.60 nm, and the crystallinity of cellulose I was 69.97%. The results showed that the green and economical DES could effectively pretreat lignocellulosic materials, providing a prospect for future utilization and the separation of LCNC.

Unraveling the role of Fe5C2 in CH4 formation during CO2 hydrogenation over hydrophobic iron catalysts

The production of value-added hydrocarbons by CO2 hydrogenation over iron (Fe) catalysts is an emerging platform reaction in CO2 utilization. However, CH4 forming in all hydrogenation reactions is undesirable. We focus on the role of Fe5C2 active species in CH4 formation during CO2 hydrogenation catalysis. Thus, Fe5C2 was manipulated by covering a hydrophobic shell to clarify the pathway of CH4 formation. By a combination of TPSR, in situ spectroscopies and DFT calculations, the variation in the mechanism of CH4 formation with the content of hydrophobic shell has been revealed. Meanwhile, the enhancement of H2O retention on the hydrophobic shell surface of Fe5C2 was found to inhibit the activation of CO2 by increasing energy barriers of C-C coupling reactions. Deep insights into the tunable role of Fe5C2 in the formation of CH4 can help for the further design of high performance catalysts for this reaction.

Interfacial reinforcement of core-shell HMX@energetic polymer composites featuring enhanced thermal and safety performance

The weak interface interaction and solid-solid phase transition have long been a conundrum for 1,3,5,7-tetranitro-1,3,5,7-tetraazacyclooctane (HMX)-based polymer-bonded explosives (PBX). A two-step strategy that involves the pretreatment of HMX to endow –OH groups on the surface via polyalcohol bonding agent modification and in situ coating with nitrate ester-containing polymer, was proposed to address the problem. Two types of energetic polyether—glycidyl azide polymer (GAP) and nitrate modified GAP (GNP) were grafted onto HMX crystal based on isocyanate addition reaction bridged through neutral polymeric bonding agent (NPBA) layer. The morphology and structure of the HMX-based composites were characterized in detail and the core-shell structure was validated. The grafted polymers obviously enhanced the adhesion force between HMX crystals and fluoropolymer (F2314) binder. Due to the interfacial reinforcement among the components, the two HMX-based composites exhibited a remarkable increment of phase transition peak temperature by 10.2°C and 19.6°C with no more than 1.5% shell content, respectively. Furthermore, the impact and friction sensitivity of the composites decreased significantly as a result of the barrier produced by the grafted polymers. These findings will enhance the future prospects for the interface design of energetic composites aiming to solve the weak interface and safety concerns.

Rapid determination of the shell content in cocoa products using FT-NIR spectroscopy and chemometrics

The determination of the cocoa shell content is of interest because a high shell content causes a reduction in the quality of cocoa products. Consequently, the aim of the present study was the development of a routinely applicable method for the quantitation of shell material in cocoa nibs. For this, 51 fermented cocoa samples of different varieties from 14 cocoa growing countries covering the crop years 2012–2017 were acquired. Admixtures of cocoa nibs with shell material were prepared in a range of 0–20% cocoa shell and subsequently analysed by Fourier transform near-infrared spectroscopy (FT-NIRS). Support vector machine regression models were created, which enabled the prediction of the cocoa shell content in a mixing ratio range of 0–20% with an RMSE of 2.05% and a R2 of 0.88 and in a range of 0–10% with an RMSE of 1.70% and a R2 of 0.72. This predictive capability suggests that the presented method is suitable for rapid determination of cocoa shell content in cocoa nibs. In addition, it was demonstrated that the method is applicable to other relevant cocoa matrices, as the prediction of the shell content of several industrial cocoa masses by the FT-NIRS-based model showed good consistency with the prediction by liquid chromatography–mass spectrometry. This emphasizes that FT-NIRS combined with chemometrics has great potential for the determination of cocoa shell content in cocoa nibs and cocoa masses in routine analysis, such as incoming inspection.