scholarly journals Oat-hull cellulose nitrates for explosive compositions

2019 ◽  
Vol 487 (4) ◽  
pp. 391-395
Author(s):  
G. V. Sakovich ◽  
V. V. Budaeva ◽  
А. А. Korchagina ◽  
Yu. А. Gismatulina ◽  
N. V. Kozyrev ◽  
...  
Keyword(s):  
High Viscosity ◽  
Scanning Calorimetry ◽  
High Chemical ◽  
Oat Hulls ◽  
Mixed Acid ◽  
Chemical Structures ◽  
Chemical Purity ◽  
Cellulose Nitrates ◽  
Composite Explosives ◽  
High Chemical Stability

Cellulose nitrates similar in basic properties to high-viscosity lacquer-grade Colloxyline were synthesized by esterification of pulp with mixed acid. The pulp was isolated from the easily renewable domestic feedstock - oat hulls - the agro-industrial waste. The cellulose nitrate test samples were comparatively evaluated. Infrared and 13C NMR spectroscopies confirmed the chemical structures were identical. It was established by differentiated scanning calorimetry and ampule chromatography that the samples had a high chemical purity. The cellulose nitrates were found to have satisfactory impact and friction sensitivities of 50 mm and 1200 kgf/cm2 and exhibit a good chemical compatibility and a high chemical stability when blended with plasticizers. The findings suggest that it is advisable to use oat-hull cellulose nitrates as the component of composite explosives. 

scholarly journals AUTOCLAVING CELLULOSE NITRATES OBTAINED FROM FRUIT SHELLS OF OATS

2019 ◽  
Vol 63 (1) ◽  
pp. 92-98
Author(s):  
Anna A. Korchagina ◽  
Yulia A. Gismatulina ◽  
Vera V. Budaeva ◽  
Aleksey A. Kukhlenko ◽  
Natalia P. Vdovina ◽  
...  
Keyword(s):  
High Temperature ◽  
Chemical Stability ◽  
Scanning Calorimetry ◽  
High Chemical ◽  
Oat Hulls ◽  
Ether Mixture ◽  
Study Results ◽  
High Specific Heat ◽  
Chemical Purity ◽  
Cellulose Nitrates

Besides the targeted viscosity decrease, the high-temperature autoclaving of cellulose nitrates (CNs) can provide one of the key properties – chemical stability – which governs the operational process safety and guaranteed shelf life of CN-based products. Here we report the study results of the autoclaving of cellulose nitrates derived by esterification of pulp with mixed sulfuric-nitric acids. The pulp was obtained from an easily renewable domestic feedstock – oat hulls – agro-industrial residue. On the basis of experiments, regression relationships are suggested herein that enable the prediction of basic properties of CNs, depending on autoclaving time. The optimum high-temperature autoclaving time was identified that allows oat-hull CNs to be produced with the following characteristics: 12.14% nitrogen content, 12 mPa·s viscosity and 98% solubility in alcohol-ether mixture, which are similar to the characteristics of dinitrocellulose (Colloxyline-N). Ampule chromatography confirmed that the resultant CNs had a high chemical stability. The quantity of nitrogen oxide from thermal decomposition of CNs (90 °С, 192 h) was found to be 0.35 ml/g and was not above the permissible level for dinitrocellulose. Differential scanning calorimetry revealed that the oat-hull CNs are characterized by a high onset temperature of decomposition (200 °С) and a high specific heat of decomposition (7.36 kJ/kg), indicating a high chemical purity of the resultant product. The findings presented herein justify the use of oat-hull CNs in the manufacture of gun-propellant grains and composite explosives.

scholarly journals Ionic Liquids: Efficient Media for the Lipase-Catalyzed Michael Addition

Molecules ◽  
2018 ◽  
Vol 23 (9) ◽  
pp. 2154 ◽  
Author(s):  
Yunchang Fan ◽  
Dongxu Cai ◽  
Xin Wang ◽  
Lei Yang
Keyword(s):  
Ionic Liquids ◽  
Lipase Activity ◽  
Michael Addition ◽  
Alkyl Chain ◽  
Hydroxyl Group ◽  
Domain Formation ◽  
High Chemical ◽  
Chemical Structures ◽  
Reaction Media ◽  
High Chemical Stability

Recently, ionic liquids (ILs) have been regarded as ideal media for non-aqueous bio-catalysis. In this work, the synthesis of warfarin by the lipase-catalyzed Michael addition in IL media and the parameters that affected the warfarin yield were investigated. Experimental results demonstrated that the chemical structures of the ILs were a major factor for influencing the warfarin yield. The ILs containing the NTf2– anion were suitable reaction media due to the high chemical stability of this anion. The incorporation of the hydroxyl group on the IL cation significantly improved the lipase activity due to the H2O-mimicking property of this group. The lipase activity decreased by increasing the alkyl chain length on the IL cation due to the non-polar domain formation of the IL cation at the active site entrance of lipase. The ILs and lipase could be reused no less than five times without reduction in the warfarin yield.

scholarly journals PROSPECTS OF CELLULOSE NITRATES FROM UNCONVENTIONAL FEEDSTOCKS FOR USE IN COMPOSITE EX-PLOSIVES

2019 ◽  
pp. 259-268 ◽  
Author(s):  
Геннадий (Gennadiy) Викторович (Viktorovich) Сакович (Sakovich) ◽  
Вера (Vera) Владимировна (Vladimirovna) Будаева (Budaeva) ◽  
Анна (Anna) Александровна (Aleksandrovna) Корчагина (Korchagina) ◽  
Юлия (Yuliya) Александровна (Aleksandrovna) Гисматулина (Gismatulina)
Keyword(s):  
Practical Importance ◽  
Research Problem ◽  
Degree Of Polymerization ◽  
Short Fibers ◽  
Wood Cellulose ◽  
Oat Hulls ◽  
Cellulosic Fibers ◽  
Mixed Acid ◽  
Industrial Grade ◽  
Cellulose Nitrates

Research on the synthesis of in-demand industrial-grade cellulose nitrates from unconventional feedstocks such as Miscanthus, oat hulls, intermediate flax straw is of the most immediate interest due to a lack of national cotton and to encountered problems with wood cellulose. The celluloses derived herein from the said unconventional feedstocks are inhomogeneous in nature, are composed mostly of short fibers, and have non-cellulosic constituents as opposed to elite cotton – these all pose certain difficulties in developing such a nitrocellulose production technology. Besides, it is worth noting that cellulosic fibers of the said feedstocks are peculiar in nature on their own. The findings obtained herein suggest that the research problem can successfully be solved. The pulp samples obtained in this study from the unconventional biomasses by the nitric-acid process have 85−95% α-cellulose and 580−1420 degree of polymerization. These specimens similar in properties to industrial Colloxylin were obtained under optimal synthetic conditions for highly soluble cellulose nitrates by using commercial mixed acid: 11.97–12.29% N, 8–15 mPa∙s, and 98% solubility in alcohol–ester mixture. The morphological features of the resultant cellulose nitrates were characterized by scanning electron microscopy. Infrared spectroscopy revealed the intrinsic frequencies (2560–2550, 1670–1660, 1650–1620, 1280–1270, 830–810, 750–740, 680–670 cm-1) that identify the resultant products as cellulose nitroesters. The practical importance of this research is that the nitrocelluloses obtained from the unconventional non-woody feedstocks can be used as the promising component in the manufacture of explosive formulations.

scholarly journals Highly soluble cellulose nitrates from unconventional feedstocks

2018 ◽  
Vol 243 ◽  
pp. 00005
Author(s):  
Yulia Gismatulina ◽  
Anna Korchagina ◽  
Vera Budaeva ◽  
Gennady Sakovich
Keyword(s):  
Chemical Shifts ◽  
Temperature Treatment ◽  
Exothermic Peak ◽  
High Temperature Treatment ◽  
Absorption Bands ◽  
Oat Hulls ◽  
Mixed Acid ◽  
Nitration Product ◽  
Cellulose Nitrates ◽  
C Nmr

Celluloses isolated by the nitric-acid process from domestic unconventional feedstocks such as Miscanthus, oat hulls, and intermediate flax straw were used herein to produce cellulose nitrates (CNs) with a high solubility. For the synthesis of CNs, a commercial technique was employed that involves nitration of cellulose with mixed acid containing 14 wt.% water followed by high-temperature treatment of the nitration product in acidic, alkaline, and neutral environments. The obtained CNs are similar in physicochemical attributes: 12.04–12.26% mass fraction of nitrogen, 10–14 mPa·s viscosity, and 98% solubility in alcohol– ester mixture. FTIR spectra of CNs had absorption bands (2559–2557, 1646–1631, 1277–1271, 825–812, 747–744, 683–680 cm-1) typical of nitro group vibrations. 13C NMR spectra showed chemical shifts representative of 6-mononitrocellulose, 2,6-dinitrocellulose, 3,6-dinitrocellulose, and 2,3,6-trinitrocellulose. DSC revealed that the resultant CNs were highly chemically pure with an exothermic peak at 209–212°С. The CNs obtained from the said unconventional feedstocks were compared with a commercial, highviscosity, lacquer-grade Colloxylin derived from cotton cellulose, as well as with other commercial Colloxylins, to show that the experimental CNs meet the requirements for comercial grades. Thus, the CNs obtained from the unconventional feedstocks are promising candidates as the component of composite explosives.

Star-shaped arylacetylene resins derived from silicon

2020 ◽  
Vol 40 (8) ◽  
pp. 676-684
Author(s):  
Niping Dai ◽  
Junkun Tang ◽  
Manping Ma ◽  
Xiaotian Liu ◽  
Chuan Li ◽  
...  
Keyword(s):  
High Performance ◽  
Room Temperature ◽  
Mechanical Test ◽  
Flexural Modulus ◽  
Mechanical Analysis ◽  
Reinforced Composites ◽  
Scanning Calorimetry ◽  
Chemical Structures ◽  
Structures And Properties ◽  
High Performance Resin

AbstractStar-shaped arylacetylene resins, tris(3-ethynyl-phenylethynyl)methylsilane, tris(3-ethynyl-phenylethynyl) phenylsilane, and tris (3-ethynyl-phenylethynyl) silane (TEPHS), were synthesized through Grignard reaction between 1,3-diethynylbenzene and three types of trichlorinated silanes. The chemical structures and properties of the resins were characterized by means of nuclear magnetic resonance, fourier-transform infrared spectroscopy, Haake torque rheomoter, differential scanning calorimetry, dynamic mechanical analysis, mechanical test, and thermogravimetric analysis. The results show that the melt viscosity at 120 °C is lower than 150 mPa⋅s, and the processing windows are as wide as 60 °C for the resins. The resins cure at the temperature as low as 150 °C. The good processabilities make the resins to be suitable for resin transfer molding. The cured resins exhibit high flexural modulus and excellent heat-resistance. The flexural modulus of the cured TEPHS at room temperature arrives at as high as 10.9 GPa. Its temperature of 5% weight loss (Td5) is up to 697 °C in nitrogen. The resins show the potential for application in fiber-reinforced composites as high-performance resin in the field of aviation and aerospace.

scholarly journals High-Tribological-Performance Polymer Nanocomposites: An Approach Based on the Superlubricity State of the Graphene Oxide Agglomerates

Polymers ◽  
2021 ◽  
Vol 13 (14) ◽  
pp. 2237
Author(s):  
Eder H. C. Ferreira ◽  
Angela Aparecida Vieira ◽  
Lúcia Vieira ◽  
Guilhermino J. M. Fechine
Keyword(s):  
Graphene Oxide ◽  
High Viscosity ◽  
Tribological Performance ◽  
Multilayer Graphene ◽  
High Concentration ◽  
Scanning Calorimetry ◽  
Mechanical Reinforcement ◽  
Transmission Electron ◽  
Twin Screw ◽  
Mechanical Tensile

Here, nanocomposites of high-molecular-weight polyethylene (HMWPE) and HMWPE-UHMWPE (80/20 wt.%) containing a low amount of multilayer graphene oxide (mGO) (≤0.1 wt.%) were produced via twin-screw extrusion to produce materials with a higher tribological performance than UHMWPE. Due to the high viscosity of both polymers, the nanocomposites presented a significant concentration of agglomerates. However, the mechanical (tensile) and tribological (volumetric loss) performances of the nanocomposites were superior to those of UHMWPE. The morphology of the nanocomposites was investigated using differential scanning calorimetry (DSC), microtomography, and transmission electron microscopy (TEM). The explanation for these results is based on the superlubricity phenomenon of mGO agglomerates. It was also shown that the well-exfoliated mGO also contained in the nanocomposite was of fundamental importance as a mechanical reinforcement for the polymer. Even with a high concentration of agglomerates, the nanocomposites displayed tribological properties superior to UHMWPE’s (wear resistance up to 27% higher and friction coefficient up to 57% lower). Therefore, this manuscript brings a new exception to the rule, showing that agglomerates can act in a beneficial way to the mechanical properties of polymers, as long as the superlubricity phenomenon is present in the agglomerates contained in the polymer.

scholarly journals Preparation, Thermal, and Thermo-Mechanical Characterization of Polymeric Blends Based on Di(meth)acrylate Monomers

Polymers ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 878
Author(s):  
Krystyna Wnuczek ◽  
Andrzej Puszka ◽  
Łukasz Klapiszewski ◽  
Beata Podkościelna
Keyword(s):  
Mechanical Analysis ◽  
Attenuated Total Reflection ◽  
Scanning Calorimetry ◽  
Force Microscopy ◽  
Chemical Structures ◽  
Atomic Force ◽  
Polymeric Blends ◽  
Ft Ir ◽  
Acrylate Monomers ◽  
Synthesized Materials

This study presents the preparation and the thermo-mechanical characteristics of polymeric blends based on di(meth)acrylates monomers. Bisphenol A glycerolate diacrylate (BPA.GDA) or ethylene glycol dimethacrylate (EGDMA) were used as crosslinking monomers. Methyl methacrylate (MMA) was used as an active solvent in both copolymerization approaches. Commercial polycarbonate (PC) was used as a modifying soluble additive. The preparation of blends and method of polymerization by using UV initiator (Irqacure® 651) was proposed. Two parallel sets of MMA-based materials were obtained. The first included more harmless linear hydrocarbons (EGDMA + MMA), whereas the second included the usually used aromatic copolymers (BPA.GDA + MMA). The influence of different amounts of PC on the physicochemical properties was discussed in detail. Chemical structures of the copolymers were confirmed by attenuated total reflection–Fourier transform infrared (ATR/FT-IR) spectroscopy. Thermo-mechanical properties of the synthesized materials were investigated by means of differential scanning calorimetry (DSC), thermogravimetric (TG/DTG) analyses, and dynamic mechanical analysis (DMA). The hardness of the obtained materials was also tested. In order to evaluate the surface of the materials, their images were obtained with the use of atomic force microscopy (AFM).

Thermal properties of polybenzoxazine exhibiting improved toughness: Blending with cyclodextrin and its derivatives

2021 ◽  
pp. 095400832110130
Author(s):  
Hailong Li ◽  
Sipei Zhao ◽  
Li Pei ◽  
Zihe Qiao ◽  
Ding Han ◽  
...  
Keyword(s):  
Thermal Properties ◽  
Hydrogen Bonds ◽  
High Performance ◽  
Practical Application ◽  
Scanning Calorimetry ◽  
Thermoset Resins ◽  
Chemical Structures ◽  
Microscopy Techniques ◽  
Fractured Surface ◽  
Scanning Electron

Polybenzoxazines are emerging as a class of high-performance thermoset polymers that can find their applications in various fields. However, its practical application is limited by its low toughness. The cyclic β-cyclodextrin and a newly synthesized derivative (β-cyclodextrin-MAH) were separately blended with benzoxazine to improve the toughness of polybenzoxazine. The results revealed that the maximum impact strength of the blend was 12.24 kJ·m−2 and 14.29 kJ·m−2 when 1 wt.% of β-Cyclodextrin and β-Cyclodextrin-MAH, respectively, were used. The strengths were 53% and 86% higher than that of pure polybenzoxazine. The curing reaction, possible chemical structures, and fractured surface were examined using differential scanning calorimetry, Fourier transform infrared spectroscopy, and scanning electron microscopy techniques to understand the mechanism of generation of toughness. The results revealed that the sea-island structure and the presence of hydrogen bonds between polybenzoxazine and β-cyclodextrin and β-cyclodextrin-MAH resulted in the generation of toughness. Furthermore, the curves generated during thermogravimetric analysis did not significantly change, revealing the good thermal properties of the system. The phase-separated structure and the hydrogen bonds present in the system can be exploited to prepare synergistically tough polybenzoxazine exhibiting excellent thermal properties. This can be a potential way of modifying the thermoset resins.

COMPRESSIVE STRENGTH AND EXPLOSIVE CHARACTERISTICS OF POLYMER-BONDED EXPLOSIVES BASED ON HEXOGEN AND FLUOROELASTOMERS

2020 ◽  
pp. 76-83
Author(s):  
Nguyen Trung Toan
Keyword(s):  
Compressive Strength ◽  
Vinylidene Fluoride ◽  
High Energy ◽  
High Chemical ◽  
Energy Characteristics ◽  
Coating Method ◽  
Polymer Bonded Explosives ◽  
Friction Sensitivity ◽  
The Impact ◽  
High Chemical Stability

This paper describes the formulation of two polymer-bonded explosives based on RDX (hexahydro-1,3,5- trinitro-1,3,5-triazine) and fluoroelastomer binders by the water-slurry coating method. The fluoroelastomers are poly(VDF-HFP) (vinylidene fluoride-hexafluoropropene copolymer) and poly(VDF-CTFE) (vinylidene fluoride-chlorotrifluoroethylene copolymer). It has been observed that the impact sensitivity and the friction sensitivity of PBX samples were significantly lower than that of the single RDX. Results also showed that two PBX formulations have high chemical stability, high energy characteristics, and equivalent to some PBX in the world. Finally, the compressive strength of these PBX compositions was found in the range of 8-12 MPa.

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