Temperature Of Maximum Weight Loss Rate Research Articles

Comprehensive experimental investigations on Co-combustion dynamics and multi-pollutant formation characteristics of coal gangue and biomass in oxy-fuel atmosphere

Based on the co-combustion principle of coal gangue and biomass, the combustion characteristics, kinetic mechanisms, and pollutant emission characteristics of mixed coal gangue and wheat straw in oxy-fuel atmosphere were investigated by conducting experiments with a thermogravimetric analyzer and a tube furnace in this paper. The results indicated that the comprehensive combustion characteristics, reaction rate and burnout rate of the samples can be improved with the increase of O2 concentration in oxy-fuel atmosphere. When O2 concentration is 50 %, the emission peaks of pollutants SO2 and NOx are the highest. The increase of biomass content can accelerate the combustion reaction rate, increase the total weight loss rate, enhance the comprehensive combustion characteristics of the samples significantly, and reduce the release of SO2. A faster heating rate corresponds to higher ignition temperature, burnout temperature, and the maximum weight loss rate temperature, leading to the improvement of comprehensive combustion characteristics and flammability. The combustion temperature has a significant effect on pollutant release, and the release of CO and SO2 is relatively low under the condition of 900∼1000 °C. Therefore, the use of oxy-fuel co-combustion technology holds the potential to significantly improve the combustion performance of coal gangue, reduce pollutant emissions, and provide a theoretical guidance for the resource utilization of coal gangue and biomass.

Double-hindered phenolic SiO2 composites with excellent oxidation resistance and thermal stability for enhanced thermal oxidation stability of PPS

In recent years, loading antioxidants onto inorganic nanoparticles has attracted increasing interest. However, the existing studies not only have low antioxidant loading efficiency, but also ignore the relationship between structural changes and antioxidant properties before and after antioxidant modification, greatly limiting the improvement of the antioxidant properties of composites and their application scope. In this work, we successfully prepared bis-hindered phenolic antioxidants containing silica hydroxyl groups (Bis-mAO) and loaded them onto silicon dioxide (SiO2) to get the nanocomposites (Bis-mAO-SiO2). The melt blending method further prepared the corresponding polyphenylene sulfide (PPS)/Bis-mAO-SiO2 composites. The results showed that the higher antioxidant loading and more suitable antioxidant structure made Bis-mAO-SiO2 possess excellent antioxidant properties. The prepared PPS/Bis-mAO-SiO2 composites remained stable under high temperatures and oxygen environments. Impressively, the maximum weight loss rate temperature of PPS/Bis-mAO-SiO2 was increased by 11.60 °C compared to that of PPS, and after accelerated thermal oxidation at 220 °C for 24 h, the relative intensity ratio between O and C of PPS/Bis-mAO-SiO2 only increased to 0.086, much lower than 0.132 for PPS. Moreover, the viscosity of PPS/Bis-mAO-SiO2 only increased by 29.05 % and 88.75 % after accelerated thermal oxidation at 220 °C for 12, 24 h. Compared, PPS's viscosity increased substantially by 79.22 % and 250.3 %, respectively. This meant that the Bis-mAO-SiO2 successfully achieved a synergistic integration of high antioxidant properties and thermal stability, implying that the work offered a strategy for fabricating high-temperature resistant antioxidant composites.

Effect on the oxidation characteristic at lignite of two types of endogenous microorganisms from coal

In recent years, coal biotechnology has gained considerable popularity due to its economic, eco-friendly, and sustainable advantages, which offer a novel perspective and pathway for the development of green technologies aimed at preventing and controlling coal spontaneous combustion (CSC). Two endogenous microorganisms from lignite were succeeded in extracting in this work, namely Aspergillus and Bacillus velezensis. Subsequently, the effect of these microorganisms on the microscopic structure and macroscopic oxidation characteristics of coal was investigated by X-ray diffraction, Fourier-transform infrared spectroscopy, and thermogravimetric analysis. The results revealed that both Aspergillus and Bacillus velezensis treatments altered the microcrystalline structure of the coal, disrupting the aliphatic hydrocarbon structure and oxygen-containing functional groups of the coal molecules. Particularly, the OH − O hydrogen bond of two kinds of microbial treatment coal samples content respectively decreased significantly by 17.29 % and 11.06 % compared to the raw coal sample. However, the effects of different microorganisms on coal varied. Thermodynamic behavior demonstrated that the critical temperature of the two treated coal samples was delayed by 29.44 °C and 26.62 °C, and the ignition temperature was delayed by 11.31 °C and 5.18 °C. Overall, all characteristic temperature points of the Aspergillus group were delayed, but the maximum weight loss rate temperature and the burn-out temperature of the Bacillus velezensis group exhibited slight advancement. The thermal mass loss characteristics also changed during the oxidation combustion stage. In addition, the average activation energies of oxidized combustion stage calculated by the Kissinger-Akahira-Sunose method were 74.26 kJ/mol and 78.61 kJ/mol, respectively, and 82.41 kJ/mol and 86.15 kJ/mol for the Friedman method, which were both increased compared to the raw coal. The results indicate that both Aspergillus and Bacillus velezensis have effects with varying degrees on the coal oxidation characteristics. It can be observed that the effect of treatment with Aspergillus is better than Bacillus velezensis from the overall changes in characteristic temperature points. This work lays the foundation for investigating the effect of microbial action on the oxidative properties of CSC.

Superhydrophobic, flexible and high thermal stable ANFs/CNTs film for controllable light driven actuators

Superhydrophobic and light-responsive actuators (SLRAs) can be driven to move on water surface remotely and in a non-contact manner, and have shown promising applications in soft robotics, environmental protection, etc. It remains a big challenge to develop high performance SLRAs with excellent thermal stability, fast light responsivity and controllable motion. Here, we propose a layer-by-layer vacuum filtration method to prepare flexible, freestanding and superhydrophobic composite films composed of alternately deposited oleylamine modified acid carbon nanotubes (O-ACNTs) and aramid nanofibers (ANFs). The composite film has excellent thermal stability with the maximum weight loss rate temperature as high as 520 ℃. The closely packed structure and strong interlayer interaction ensure the surface stability and durability of the composite film. The composite film possesses excellent photothermal conversion performance, and can maintain the structure integrity without deformation when its surface temperature reaches 208 °C. When used as a self-propelled actuator, the SLRA film can response to the light quickly and move on the water surface, and the motion speed and direction can be controlled by adjusting the irradiation intensity and position. The outstanding thermal stability guarantees the stability and reliability of the self-propelled motions. The present study opens a new avenue to design high performance SLRAs.

Effect of addition of K2CO3 on the structure of coals with different ranks by FTIR and TG/MS

K2CO3 was considered as the effective catalyst on the pyrolysis performance of coal, however, its effect on coals with different ranks and coalification jumps is unknown until now. This study aims to explore the catalytic mechanism of K2CO3 on coals with different ranks. 8 coals with a vitrinite reflectance (Ro,max) ranging from 0.68% to 1.71% were catalyzed by K2CO3. Thermogravimetric-Mass spectrometry analyzer (TG/MS) and Fourier Transform Infrared (FTIR) spectroscopy were used to characterize the structural variation before and after the addition of K2CO3. FTIR results showed that the length of aliphatic chains (CH2/CH3) decrease and then increase with the turning point near Ro,max = 1.53%, the degree of condensation of aromatic ring (DOC),aromaticity (I) decreased and the concentration of aliphatic hydrogen (Hal/H) increased for all coal samples except for DQ coal (Ro,max = 1.53%) after the addition of K2CO3, indicating the abrupt changes occurred at Ro,max = 1.53%. TG/MS results showed that both the weight loss rate and the maximum weight loss rate temperature exhibit reflection changes near 0.68% and 1.2% of Ro,max. The evolution rate of hydrogen and ethane showed turning changes near Ro,max = 1.21%, while the evolution rate of methane and benzene present transitive changes near Ro,max = 1.53%. Ro,max = 1.21% and Ro,max = 1.53% are consistent with the second and the third coalification jump, respectively. Both TG/MS and FTIR results demonstrated that the effect of K2CO3 is related to coal rank, especially the coalification jump. K2CO3 may tend to act on CC structures furthermore promote the evolution of gaseous products during pyrolysis. The results provide deeply understanding for the coalification jumps and theoretical basis for the selection of suitable catalysts with different coal ranks.

Low temperature catalytic pyrolysis performances of heated tobacco sheets by alkali/alkaline earth metal

The low temperature catalytic pyrolysis performances of heated tobacco sheets by alkali/alkaline earth metal were investigated by TG-FT-IR and Py-GC-MS. Thermogravimetric analysis showed that the maximum weight loss rate temperature of the heated tobacco sheets significantly reduced from 328 °C to 292 °C catalyzed by alkali metal Na or K catalysts, and the weight loss between 100 and 300 °C increased by 48.83% and 40.05% respectively. While alkaline earth metal Mg or Ca catalysts exerted less influence on the maximum weight loss rate temperature and the weight loss between 100 and 300 °C reduced slightly. The online infrared absorption band of pyrolysis gas shifted to lower temperature and the concentration of pyrolysis gas increased over Na catalysts, which matched well with TG results. Moreover, the concentration of carbonyl compounds and compounds containing C-O bonds in pyrolysis gas increased significantly. The content of 2-furanmethanol, butyrolactone and megastigmatrienone in pyrolysis gas increased under the assistance of alkali metal Na or K. Model compounds research confirmed that alkali metal could catalyze low temperature pyrolysis of cellulose in heated tobacco sheets. These results demonstrated that the pyrolysis of heated tobacco sheets could be catalyzed by alkali metal catalysts at low temperature, increasing the concentration of pyrolysis gas and aroma substance. This research provided a new idea for the study of aroma and concentration enhancement of heated cigarettes through catalytic technology.

Highly Efficient Pyrolysis of Waste High-Temperature Vulcanized Silicone Rubber Assisted by Mechanochemical Milling

High-temperature vulcanized silicone rubber (HTV SIR) possesses great chemical resistance and high thermal stability, but these excellent performances also impede its recycling. In this respect, the waste HTV SIR from retired composite insulators with/without the KOH catalyst was ground by solid-state shear milling (S3M). The morphology and structure of silicone rubber powder were analyzed, and the pyrolysis behaviors of the obtained silicone rubber powders were revealed by thermogravimetry (TG) and pyrolysis gas-phase/mass spectrometry (Py-GC/MS). The results show that the mechanochemical milling via S3M could significantly reduce the particle size of silicone rubber and destroy the cross-linking structure of the waste HTV SIR, thus leading to an obvious improvement in the sol fraction. The maximum weight loss rate temperature of waste HTV SIR with the KOH catalyst assisted by mechanochemical milling was 150 °C lower than those without milling. Moreover, a greatly reduced catalytic pyrolysis duration along with more concentrated pyrolysis products at 400 °C was achieved after grinding three times. At last, the pyrolysis mechanism of the waste HTV SIR assisted by mechanochemical milling is proposed. These obtained results provide a great potential for large-scale recycling of waste silicone rubber with stable structure and complex components.

Study on the Performance of a Novel Highly Stable Nano-Hydroxyapatite Gel Foam to Inhibit Coal Spontaneous Combustion

ABSTRACT The preparation of gel foams with high stability for inhibiting coal spontaneous combustion remains a huge challenge. In this paper, a highly stable gel foam (SCTH) was developed by introducing nano-hydroxyapatite (HAP) into gel foam system (sodium alginate/calcium L-lactate/tannic acid/composite forming agent). The effects of HAP on the foam performances of SCTH were analyzed. The results showed that HAP could improve the stability of SCTH by forming hydrogen bonds, metal ion bonds with the system and interfacial barriers. After 100 days, SCTH without HAP had only 44.8% of the foam volume remaining. The SCTH with 1.2 wt% HAP had 80% of the volume remaining. In addition, the SCTH had better safety. Thermogravimetric analysis showed that the SCTH could improve the maximum weight loss rate temperature, and increase the residual weight of the coal after thermal decomposition. The coal temperature-programmed oxidation experiment showed that the SCTH could increase the temperature of coal entering the rapid oxidation stage from 120 to 190°C, and the CO inhibition rate was 85.3% at 200°C. Fire suppression experiment showed that the SCTH could reduce the temperature of burning coal by 81.9% within 10 min, thus achieving rapid fire suppression. X-ray photoelectron spectroscopy analysis showed that the SCTH could more effectively reduce the total content of C=O and -COO in coal and block the chain cycle reaction of coal. This work presents a new design idea for using multifunctional nanoparticles to prepare highly stable gel foams with excellent inhibition performance of coal spontaneous combustion.

Characteristics and mechanism of modified hydrotalcite for coal spontaneous combustion preventing

Hydrotalcite is a new fire-fighting material with a sound effect of preventing the spontaneous combustion of coal. In this paper, hydrotalcite (Zn–Mg–Al-LDHs) and rare earth element Ce-modified hydrotalcite (Zn–Mg–Al–Ce-LDHs) inhibitor samples were prepared by the co-precipitation method, respectively. The surface morphology, dispersibility, and pyrolysis properties of the inhibitor were characterized by thermogravimetric experiments. Based on thermogravimetric experiments, the effects of hydrotalcite and modified hydrotalcite containing rare earth element Ce on the spontaneous combustion characteristics of coal were studied. Combined with thermodynamic parameters, the inhibition mechanism of coal spontaneous combustion was analyzed. The results showed that Zn–Mg–Al-LDHs and Zn–Mg–Al–Ce-LDHs inhibitors were successfully prepared. Adding the two to coal can inhibit both coal samples, and the inhibition effect of Zn–Mg–Al–Ce-LDHs is more significant. The Zn–Mg–Al–Ce-LDHs inhibitor can effectively reduce the weight loss rate of coal, delay the critical temperature, and maximum weight loss rate temperature of coal samples by 6 °C and 31.5 °C, respectively, and increase the residual heat by 2.3%. The calculation of apparent activation energy shows that the average activation energies of Zn–Mg–Al–Ce-LDHs for inhibiting coal samples in the stages of water evaporation and gas desorption and thermal decomposition and combustion are 30935.256 J/mol and 76962.582 J/mol, respectively; 464.878 J/mol and 31914.233 J/mol higher than raw coal, respectively.

Experimental research on spontaneous combustion of coal oxidized by ultraviolet photocatalysis

To study the effect of ultraviolet light on the spontaneous combustion characteristics of coal, Lijiahao long-flame coal was selected for irradiation treatment with a self-made ultraviolet light irradiation device. After irradiation for 0, 1, 2, 4, and 8 h, thermogravimetric experiments and Fourier transform infrared spectroscopy experiments were carried out. Compared with the raw coal, the dry cracking temperature, the ignition point temperature, and the maximum weight loss rate temperature of coal samples irradiated for 2 h by ultraviolet light were advanced to different degrees. The ignition activation energy was 0.62, 0.56, 0.59, and 0.91 times that of the raw coal after 1, 2, 4, and 8 h of ultraviolet light irradiation. The ultraviolet light irradiation accelerated the oxidation of –CH3, –CH2−, and –OH, resulting in enhanced coal activity. It shows that ultraviolet light irradiation has a promoting effect on the spontaneous combustion of coal, and the best promotion effect is observed when ultraviolet light is irradiated for 2 h. After 2 h of ultraviolet light irradiation, compared with the raw coal, the content of ether group in the coal structure decreased by 6.79%, the content of methyl and methylene in the benzene ring decreased by 8.68%, the content of C=O and carboxylic acid increased by 30.21%, the content of hydroxy ether and hydroxyl π hydrogen bond decreased by 14.94%, and the content of self-associating hydroxyl hydrogen bonds increased by 16.59%. It shows that ultraviolet light can destroy aromatic hydrocarbons in coal, catalyze the hydrolysis reaction of esters and ethers in coal to generate –OH and –COOH, and promote the oxidative spontaneous combustion of coal.

Facile preparation and properties of superhydrophobic nanocellulose membrane

Superhydrophobic nanocellulose membrane was prepared by synergistically modifying biodegradable nanocellulose with low-carbon perfluoroorganosiloxane and ethyl orthosilicate. The effects of four kinds of low-carbon perfluoroorganosiloxanes with different structures and their ratio to ethyl orthosilicate on the hydrophobic properties of nanocellulose membrane were investigated, and then FT-IR, XPS, XRD, SEM, TEM, AFM, TG and contact angle goniometer were used to characterize the structure and hydrophobic properties of nanocellulose membrane before and after modification. It is found that when the molar ratio of 1H,1H,2H,2H-perfluorooctyltrimethoxysilane (PFOTMS) to ethyl orthosilicate (TEOS) is 1, the modified nanocellulose membrane PFOTMS-TEOS-CNF is loaded with silica nanoparticles both inside and on its surface, and a micro-nano hierarchical rough morphology with low surface energy is constructed. At this point, the root-mean-square roughness (Rq) of nanocellulose membrane is 112 nm, and the static contact angle of water droplet is 153.5°, successfully realizing superhydrophobicity. In addition, compared to unmodified nanocellulose membrane, PFOTMS-TEOS-CNF with better thermal stability includes an additional maximum weight loss rate temperature (491.2 °C). The above advantages markedly improve the shortcomings of pristine nanocellulose, such as superhydrophilicity and insufficient thermal stability, and also broadens its high-value application in many fields.

Poly (arylene ether ketone) with carboxyl groups ultrafiltration membrane for enhanced permeability and anti-fouling performance

• 1. C-PAEK ultrafiltration membrane was prepared by NIPS method to form finger-like pores and provide a transport channel for water. • 2. The introduction of carboxyl monomer improves the hydrophilicity and permeability of ultrafiltration membrane. • 3. C-PAEK ultrafiltration membrane was used for filtration of pure water /BSA solution. • 4. C-PAEK ultrafiltration membrane has high stability and excellent reusability. In this study, a novel poly (arylene ether ketone) with carboxyl groups (C-PAEK) was synthesized by adjusting the ratio of 4-carboxylphenyl hydroquinone (4C-PH) with bisphenol A (BPA). Fourier transform infrared spectroscopy (FTIR) and 1 H Proton Nuclear Magnetic Resonance ( 1 H NMR) spectra demonstrated that C-PAEK polymer was successfully synthesized by the nucleophilic polycondensation reaction. A series of C-PAEK ultrafiltration membranes were prepared by nonsolvent-induced phase separation (NIPS) method. The effect of carboxyl content on the structure and properties of C-PAEK ultrafiltration membranes was studied by scanning electron microscope (SEM), thermogravimetric analysis, porosity, water contact angle (WCA), molecular weight cut-off (MWCO), ultrafiltration and antifouling experiments. C-PAEK membranes showed the typical asymmetric structure and finger-like channels. With the increase of carboxyl content in PAEK, the WCA of membranes decreased from 76.9 ± 1.8° (M0) to 57.3 ± 1.6° (M4). In addition, the weight loss temperature of 5% and the maximum weight loss rate temperature of C-PAEK are about 432 ℃ and 502 ℃, respectively. Among the prepared membranes, the porosity (ε) of M2 with 10 wt% carboxyl groups content increased from 82.3 ± 3.6% to 91.2 ± 1.2%, but the average pore sizes (r m ) of the membranes were similar. M2 showed the highest pure water flux (511.5 L/(m 2 h)), which was 1.7 times of M0. Rejection and flux recovery rate (FRR) of were 96.4 ± 2.5% and 63.4%, respectively. Meanwhile, in the cyclic filtration experiment of C-PAEK membrane, with the increase of carboxyl groups, the FRR of both cycles was higher than that of the PAEK membrane. All results indicated that the membrane had high permeability, anti-fouling stability and durability. In short, the novel C-PAEK ultrafiltration membrane functionalized with 4C-PH demonstrated great potential for pollutant removal in the fields of pharmaceutical industry, food industry and bioengineering.

The use of modified silica to control the morphology of polyamide 11 and poly(phenylene oxide) blends

Silica having amine functional groups (A-SiO2) obtained by the sol-gel process was used to improve compatibility of polyamide 11 and poly(phenylene oxide) (PA11/PPO 80/20) blend via reactive extrusion in a co-rotating twin screw extruder. Amine functional groups of A-SiO2 can react with the carboxyl groups of PA11 to form graft copolymer with PA11 which can efficiently control the phase morphology of the blend. Silica, thanks to the reinforcing effect, significantly increased stiffness of PA11/PPO blend. On the other hand, it greatly improved impact strength and reduced the crystallinity without affecting the crystallization temperature of PA11due to excellent compatibilizing effect. SEM results showed that despite the lower content of PPO, it formed a continuous phase and PA11 - a dispersed. The addition of A-SiO2 changed the morphology from the droplet-matrix to co-continuous with interpenetrating phases. The greatest size-reduction of both phases, reflecting the highest impact toughness, was observed for the content of 3 wt % A-SiO2. With a higher silica loading, phase inversion was observed with the reappearance of the droplet structure, resulting in a slight decrease in impact strength and significant in elongation at break. TGA showed that the composites exhibited better thermal properties as evidenced by the higher initial degradation temperature (Tonset) and the maximum weight loss rate temperature (Tmax).

Preparation and properties of hydrotalcite microcapsules for coal spontaneous combustion prevention

Microcapsule materials are a new type of composite fire-extinguishing material that show good effects in preventing the spontaneous combustion of coal. In this paper, polyethylene glycol 6000 (PEG6000) was selected as the wall material, and hydrotalcite (LDHs) was selected as the core material. Microencapsulated LDHs samples with different core-to-wall ratios were prepared by melting dispersion and condensation. Scanning electron microscopy coupled with energy dispersive spectroscopy (SEM-EDS), Fourier transform infrared spectroscopy (FTIR), thermogravimetry/differential scanning calorimetry (TG/DSC) and other experiments were used to characterize the surface morphology, dispersion, coating, pyrolysis and other characteristics of the microcapsules. On this basis, the microcapsules were mechanically mixed with a coal sample to prepare a chemically inhibited coal sample. Based on TG/DSC experiments, the effect of microcapsules with different core-to-wall ratios on the characteristics of coal spontaneous combustion was studied. Combined with thermokinetic parameters, the inhibition mechanism of the microcapsules with different core-to-wall ratios on coal spontaneous combustion was analyzed. The results showed that LDH-PEG6000 microcapsules were successfully prepared. The thermal reactivities and inhibition mechanism of microcapsules with different core-to-wall ratios were different, and the best effect was obtained when the core-to-wall ratio was 1:5. This microcapsule material can reduce the weight loss rate and heat release of coal, increase the critical temperature and maximum weight loss rate temperature by 8.8 °C and 33.6 °C, respectively, and increase the apparent activation energy of water evaporation and gas desorption stage by 13.42 kJ/mol and the thermal decomposition stage and combustion stage by 88.64 kJ/mol. Resistance microcapsules can effectively inhibit the coal spontaneous combustion reaction In addition, this research provides new ideas for solving the problem of coal spontaneous combustion in the goaf caused by the fully mechanized top coal caving technology and enriches the technical means of fire prevention.

Preparation and properties of ammonium polyphosphate microcapsules for coal spontaneous combustion prevention

ABSTRACT Ammonium polyphosphate (APP) is a type of fire-fighting material that has excellent performance; however, it also has the disadvantage of facile deliquescence. Microcapsule technology is therefore employed in this study to use melamine resin as encasing material in the preparation of melamine–formaldehyde resin-microencapsulated APP. The performance of prepared microcapsules is characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, and thermogravimetric experiments. The experimental results show that the same APP characteristic peaks (e.g., N-H stretching vibration peaks) and characteristic absorption peaks of melamine-formaldehyde (MF) resin (e.g., vibration peak of MF ring) are exhibited by the microcapsules. Furthermore, the coated microcapsule surface is rough because of the adsorption of solid particles, indicating that the wall material successfully covers the core material. Thermogravimetric analysis shows that the microcapsules can effectively increase and decrease the maximum weight loss rate temperature and maximum weight loss rate, respectively. When the microcapsule content constitutes 15% of the total sample mass, the maximum weight loss rate and coal temperature decrease and increase by 0.58%/min and 13°C, respectively. This significantly inhibits the composite coal-oxygen process, indicating the improved fire-fighting performance afforded by microcapsules. The Research provides a new direction for the development of fire-fighting materials.

Superior dispersion led excellent performance of wood-plastic composites via solid-state shear milling process

Wood-plastic composites as a kind of lightweight and green biomaterials are attracting great interest from academia and industry. However, challenges for effective wood flour (WF) dispersion in wood-plastic composites have hindered the desired property enhancements and limits their wider applications. This study reported an effective method to produce linear low-density polyethylene (LLDPE)/WF composite with superior WF dispersion via solid-state shear milling (S3M) for the first time. Such well-dispersed WF results in a significant enhancement in processability and shows a decrease of viscosity from 8021 Pa s to 3893 Pa s, which is closer to that of neat LLDPE (2286 Pa s) at shear rates of 100−1. The S3M processed composites also show a 26.5% increase and maximum tensile strength reached 31.1 MPa. In addition to the excellent mechanical performance, the water absorption of composites was as low as 0.22% after 840 h immersion, which is lower than most reported data. Moreover, the S3M processed composites exhibit a significant increase in LLDPE crystallinity and a dramatic 66 °C increase in maximum weight loss rate temperature in air. This work was conducted without any surface modification or use of compatibilizer, this new method will have potential applications in producing excellent performance wood-plastic composites in the industrial process.

Co-pyrolysis Characteristics of Torrefied Coconut Shell and Coal

The co-pyrolysis of torrefied coconut shell (TCS) and Shenhua coal (SHC) was performed using a thermogravimetric analyzer (TGA). The pyrolysis and interaction characteristics of the raw feed materials (TCS and SHC) along with selected mass blend ratios were investigated. Compared to pyrolysis alone, the blend ( Blend1-2 and Blend2-1) have one more maximum weight loss rate peaks. Initial decomposition temperature and maximum weight loss rate temperature gradually increase with increasing heating rate. There are two kinds of interaction was observed: physical and chemical interactions. Both the heating rate and the blending ratio have influence on the interaction. There is no chemical interaction at 3°C/min heating rate, and the physical dominates the interaction progress. At a heating rate of 3oC/min, both interactions exist, and the physical process dominates the progress of the interaction. The higher the mass ratio of TCS in the blend, the more significant the physical interaction.

In situ generated silica reinforced polyvinyl alcohol/liquefied chitin biodegradable films for food packaging

In previous report, polyvinyl alcohol/liquefied ball-milled chitin (PVA/LBMC) blend films with good antibacterial activity were successfully prepared. To further develop a biodegradable food packaging material, various amounts of nano-silica were introduced in situ by the hydrolysis of Na2SiO3 to give a series of silica-reinforced PVA/LBMC blend films. Their structure, morphology, mechanical and thermal properties, food preservation and degradation behavior in soil were comprehensively characterized. The results showed that when the content of Na2SiO3 was 0.2 wt %, the blend film 4PVA-LBMC-0.2Si displayed the optimized performance. Its tensile strength, and the maximum weight loss rate temperature reached 51 MPa and 307 ℃, respectively, which were significantly improved than those of silica-free film. The preservation tests of cherries showed its good fresh keeping performance. Although the degradation rate of silica-reinforced blend films in the soil was slightly decreased, it remained at a good level of 43 % after 30 days of burial.

Experimental study of the influence of water on spontaneous combustion of coal containing pyrite

ABSTRACT In order to investigate the influence of water content on spontaneous combustion characteristics of coal containing pyrite, the Thermogravimetric analysis (TG), Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) was carried out. The XRD results reveal high pyrite in the Yangquan anthracite. The water loss end temperature and initial reaction temperature increased, with the interval between them decreasing, and the maximum weight loss rate temperature declined as the water content increased. The activation energy reduced, and the mechanism function of coal sample changed from chemical reaction to chemical reaction of the third order after adding water. The heat release value increased by 14.4%in sample YQ4 compared with sample YQ1. Combustion produced mainly SO2, CO2 and H2O, with SO2 as the primary gas. Gas generation curves were partially interlaced.

Pyrolysis and combustion characteristics and reaction kinetics of carbon fiber/epoxy composites

The pyrolysis and combustion characteristics and reaction kinetics of epoxy resin matrix and carbon fiber/epoxy composites based on epoxy resin were studied by cone calorimetry and thermogravimetry. The results show that with the increase in thermal radiation intensity (increase from 25 kW m−2 to 55 kW m−2), the average ignition time of the experimental samples decreases, the peak heat release rate increases, and the peak appears earlier. Carbon fiber can inhibit the pyrolysis and combustion of epoxy resin. It can effectively inhibit the droplet and splash phenomenon during the combustion process. The time of ignition, heat release, and the peak value of the heat release rate are delayed. The ignition temperature of foam core materials in carbon fiber/epoxy foam laminates is low, which makes the average ignition time and peak heat release rate appear earlier. The theoretical critical heat fluxes of four experimental samples (epoxy resin matrix, carbon fiber/epoxy bidirectional woven fabric, carbon fiber/epoxy prepreg, and carbon fiber/epoxy foam laminate) were obtained by calculation. The theoretical critical heat fluxes are 12.12 kW m−2, 13.21 kW m−2, 11.12 kW m−2, and 0.93 kW m−2, respectively. The pyrolysis of carbon fiber/epoxy bidirectional woven fabric can be divided into three stages: two stages of epoxy resin matrix decomposition and carbon fiber decomposition. The heating rate has a significant influence on the pyrolysis process. With the increase in heating rate, the maximum weight loss rate temperature moves toward high temperature. The Kissinger method and Flynn-Wall-Ozawa method were used to analyze the pyrolysis kinetics. The apparent activation energy and pre-exponential factors were obtained at different heating rates. The results obtained by the two methods are basically the same. When the pyrolysis temperature of the three composites reached 450 °C, the mass loss was 20%, 17%, and 28%, respectively. This shows that the thermal stability of carbon fiber/epoxy prepreg is the best, the thermal stability of the two-way woven fabric of carbon fiber is better, and the thermal stability of the carbon fiber sandwich board is the weakest. It is consistent with this rule at any temperature.