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Nemes, Rita; Abed, Mohammed A.; Seyam, Ahmed M.; Lublóy, Éva
doi: 10.1007/s10973-021-11167-6pmid: N/A
The residual compressive strength of eight lightweight concrete mixtures containing three commercial grading (Liapor HD 5 N, Liapor HD 7 N, and Liapor 8F) of coarse lightweight aggregate (LWA) were determined after to expose at high temperatures. Eight mixes were produced, two by normal weight aggregate and the rest by different types of LWA. The produced concrete was analyzed after high temperature exposure and the effect of using LWA, the type of LWA, and compaction method was studied. To do so, visual inspection, residual compressive strength, crack pattern, spalling, and thermoanalytical analysis were conducted. Generally, it could be concluded that concrete formulations with LWA behave more advantageous up to 500 °C, compared to those with quartz gravel aggregates. Moreover, this study found that an ideal type of LWA to produce structural concrete was Liapor HD 5 N, which was used for producing the mixes L1 and L3.
Kammar, E. A.; Gad, E. A. M.; Mousa, M. A.
doi: 10.1007/s10973-021-11112-7pmid: N/A
NixCo1−xFe2O4 (x = 0, 0.5, and 1) spinel nanoparticles (NPs) have been prepared using the ceramic method and Ni0.5Co0.5Fe2O4 using green, microwave, and sol–gel routes. The as-prepared materials were characterized by XRD, FT-IR, SEM TEM, and N2 adsorption/desorption techniques. The catalytic activity, thermal stability, and kinetic parameters of the effect of synthesized materials upon thermal decomposition of ammonium perchlorate (AP) were studied through differential scanning calorimetry (DSC) and thermogravimetric techniques (TG). The addition of 2 mass% of nanosized ferrites to AP shifted the thermal degradation temperature of AP to lower temperatures. The catalytic activity for AP thermal degradation followed the order: NiCoF-gl > NiCoF-gr > NiCoF-mic > NiCoF-cer > NiF > CoF. The kinetic parameters for the ferrite-catalyzed reaction, using the isoconversional methods for NiCoF-gl, showed a decrease in the activation energy and preexponential factor of ammonium perchlorate thermal dissociation compared with the uncatalyzed one. The thermokinetic parameters for the catalytic decomposition process were determined and a mechanism was suggested for the kinetic reaction. The DSC results showed that the decomposition temperatures of AP decreased with the addition of the ferrites. The heat releases of the AP/ferrite mixtures were 0.82, 0.89, 0.91, 0.98, 1.04 and 1.23 kJ g−1 of AP, for CoF, NiF, NiCoF-cer, NiCoF-gr, NiCoF-mic, and NiCoF-gl, respectively, compared to 0.72 kJ g−1 for neat AP.
Mailhé, Clément; Gorsse, Stéphane; Thirion, Boèce; Palomo, Elena; Duquesne, Marie
doi: 10.1007/s10973-021-11091-9pmid: N/A
An emerging dynamic calorimetry method based on infrared thermography (IRT method) has recently proven to be of great interest for the fast establishment of the phase diagrams of binary systems of organic materials (sugar alcohols, fatty acids, fatty alcohols). The methods allowed for their determination in a single 2-h experiment when standard techniques require weeks of measurements hence enabling a significant improvement of the efficiency of material screening processes. As adding a component to the system greatly increases the number of compositions to be studied (21 for binary, 231 for ternary assuming a 5 mol% increment between compositions), the IRT method may be of even greater use with increasing system complexity. This work then aims at studying the applicability of IRT for the fast establishment of phase diagrams of ternary systems with the lauric (LA), myristic (MA), and palmitic (PA) fatty acids ternary system as an illustrative case. A phase diagram in agreement with the results of the literature and with DSC measurements is established using IRT in a few hours-experiments instead of weeks to months with standard methods. The obtained results (e.g.67 mol%LA + 23 mol%MA + 10 mol%PA for the eutectic composition, occurrence of a ternary eutectic reaction at 32 °C) are promising. This technique also successfully allows for rapid exploration of the phase diagram: reconstruction of the liquidus surface, identification of the eutectic transition, 4-phase equilibrium. IRT is a particularly interesting high-throughput characterization method for the establishment of the phase diagrams of ternary (or higher-order) systems.
Tao, Lili; Xu, Yue; Liu, Lubin; Li, Bin; Xu, Miaojun
doi: 10.1007/s10973-021-11120-7pmid: N/A
A novel mono-component P/N/B-containing intumescent flame retardant poly(methylphosphonic-boric acid piperazine neopentylgcol ester) named MBPNE was synthesized. The chemical structure of MBPNE was analyzed by FTIR, 13C and 31P solid-state NMR tests. The results of thermal gravimetric analysis indicated that MBPNE possessed excellent charring capability, and its residual char was 27.5 mass% at 800 °C. Besides, MBPNE occurred melting and expansion process during charring evolution process. MBPNE was used to prepare flame retardant polyolefin elastomer (POE) composites. The 1.6 mm POE/MBPNE specimens achieved UL-94 V-0 rating and their LOI value was 25.5% when 22 mass% MBPNE was incorporated. The sheet was extinguished quickly after departing the flame, and no dripping appeared. Furthermore, the incorporation of MBPNE effectively enhanced the residual char mass after cone calorimeter tests, and the heat release was suppressed. The compact, expanded, partially graphitized and coherent char layer was generated on POE composites surface during burning process and exerted isolation effect in condensed phase. Meanwhile, the degradation products of MBPNE quenched active free radicals in gaseous phase, which effectually interrupted the combustion chain reaction of POE composites. Consequently, the POE composites were endowed excellent flame retardant performance.
Nocuń-Wczelik, W.; Pacierpnik, W.; Kapeluszna, E.
doi: 10.1007/s10973-021-11161-ypmid: N/A
The calorimetric and DTA/TG measurements were applied in testing the effect of granulated blast furnace slag originated from the storage yards of different age, added as a supplementary cementing material to the Portland cement clinker. The studies were performed with aim to evaluate the kinetics of cement hydration and the modification of hydrated paste composition in the presence of additive. The material after 20-year storage, the crushed slag after approximately 2-years storage and the new slag from the current production in the metallurgical plant were used. The slag percentage was 5 ÷ 50%. The addition of granulated blast furnace slag stored for a long time affects the standard properties of cement reducing the compressive strength at longer maturing and with the percentage of additive. This is related mainly to the reduction in the vitreous component. However, at the additive content up to 50% the binder complying with the requirements of the relevant European standards for common cements could be produced. Basing on the results of TG measurements the role of calcium carbonate, being the product resulting from the slag weathering process, acting as a grindability and setting/hardening modifying agent, was highlighted.
doi: 10.1007/s10973-021-11122-5pmid: N/A
A three-dimensional porous activated carbon (HSAC) with high adsorption properties was prepared by using hemp straw as raw material and phosphotungstate as catalyst through low-temperature hydrothermal carbonization combined with KOH high-temperature activation technology. The maximum specific surface area of activated carbon material was 2310.1 m2 g–1, and the maximum adsorption capacity of methylene blue was 2424.2 mg g–1. A series of PEG/HSAC phase change energy storage materials with different mass ratios were prepared by physical blending impregnation by using polyethylene glycol (PEG) as phase change material and porous activated carbon as carrier. Through the study of activated carbon pore structure, energy storage material structure analysis, and DSC comparative analysis, the experimental results showed that PEG and HSAC mass ratio (60/40) was the best. The latent heat of the composite was 51.5 J g–1, and the phase change temperature was 58.5 ℃. No obvious leakage occurred after 20 heat cycles. Composite phase change materials had potential applications in the field of intelligent buildings.
Fang, Manting; Zhang, Xuelai; Ji, Jun; Hua, Weisan; Zhao, Yi; Liang, Jiyuan
doi: 10.1007/s10973-021-11113-6pmid: N/A
In order to solve the phase separation problem of Na2S2O3·5H2O–CH3COONa·3H2O PCM (phase change material), sodium carboxymethyl cellulose (CMC), hydroxyethyl cellulose (HEC), xanthan gum (XG), sodium polyacrylate (PAAS) and polyacrylamide (PAM) were selected as additives. The effects of different proportions of the above thickeners on the supercooling degree, phase separation, phase change temperature and latent heat of Na2S2O3·5H2O–CH3COONa·3H2O system were studied by using the cooling curve and DSC, so as to screen the best thickener for eutectic PCM. The experimental results show that CMC, XG and PAAS can eliminate the phase separation of Na2S2O3·5H2O–CH3COONa·3H2O. Among them, the optimal ratio of CMC, XG and PAAS is 3 mass%, 3 mass% and 1 mass%, respectively. From the perspective of heat storage performance, PAAS is the optimal thickener for Na2S2O3·5H2O–CH3COONa·3H2O. The phase change temperature is 40.5 °C. The subcooling degree is about 14.7 °C, and the latent heat is about 221 J g−1. The melting time is 15 min. Only PAAS can make Na2S2O3·5H2O–CH3COONa·3H2O eutectic PCM completely exothermic at room temperature, which can not only play the role of thickener to eliminate phase separation, but also is a nucleating agent. After 100 melting-solidification cycles, the change rate of latent heat value was only 5%, and the change rate of phase transition temperature was less than 1%. Considering heat storage performance and cyclic stability, PAAS is the optimal thickener for Na2S2O3·5H2O–CH3COONa·3H2O PCM.
George, Kesiya; Mohanty, Smita; Biswal, Manoranjan; Nayak, Sanjay K.
doi: 10.1007/s10973-021-11148-9pmid: N/A
The present work studies the influence of zinc borate (ZB), magnesium hydroxide (MH) and ammonium polyphosphate (APP) as flame retardants on the curing, mechanical, thermal and flammability performances of Kevlar fibre (KF)-reinforced ethylene propylene diene monomer (EPDM) rubber composites. The flame retardant EPDM/KF composites were prepared with variable ratio of ZB, MH and APP. Thereafter, physicomechanical and thermal properties of the fire retardant EPDM/KF composites were analysed with density analysis, tensile testing, TGA analysis, SEM and cone calorimeter tests. The TGA analysis and cone calorimeter tests showed the enhancement in the flame retardant properties of the EPDM/KF composites with the addition of combined fillers with respect to the virgin counterparts. The synergistic effect of ZB and APP containing flame retardant-incorporated composites exhibited a prominence in the thermal stability and fire retardancy. Heat release rate (HRR) and total heat release rate (THR) of the ZB and APP combined fire retardant-incorporated composites were lower than the virgin EPDM.
Ageyeva, Tatyana; Kovács, József Gábor; Tábi, Tamás
doi: 10.1007/s10973-021-11145-ypmid: N/A
We selected the thirteen most effective nucleating agents for Poly(lactic acid) (PLA) from the literature, and synthesized and compounded them with two different PLA grades: 3001D (1.4% D-lactide content) and 3100HP (0.5% D-lactide content, considered PLLA). We determined the crystallinity and crystallization of PLA with different nucleating agents in identical conditions (same nucleating agent content, same cooling rate) with the help of differential scanning calorimetry. We compared the efficiency of each nucleating agent and found that for both PLA grades, Zinc PhenylPhosphonate was the most effective. However, even when nucleated PLA was injection molded into a cold mold (25 °C), it still could not fully crystallize during cooling and the heat deflection temperature did not increase significantly. The maximum achieved crystallinity, in this case, was between 32.4 and 35.7%. On the contrary, when a 90 °C “hot mold” and in-mold crystallization together were applied, the specimens achieved full crystallization during the injection molding cycle (crystallinity was between 44.5 and 50.0%), and the heat deflection temperature increased to an average of 88.8 °C. We also examined the mechanical properties of the nucleated PLA and found that the usage of nucleating agents together with a hot mold improved tensile strength, tensile modulus, and Charpy impact strength but decreased elongation at break.
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