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Natural polymer hydrogels have good mechanical properties and biocompatibility. This study designed hydroxyapatite-enhanced photo-oxidized double-crosslinked hydrogels. Hyaluronic acid (HA) and gelatin (Gel) were modified with methacrylate anhydride. The catechin group was further introduced into the HA chain inspired by the adhesion chemistry of marine mussels. Hence, the double-crosslinked hydrogel (HG) was formed by the photo-crosslinking of double bonds and the oxidative-crosslinking of catechins. Moreover, hydroxyapatite was introduced into HG to form hydroxyapatite-enhanced hydrogels (HGH). The results indicate that, with an increase in crosslinking network density, the stiffness of hydrogels became higher; these hydrogels have more of a compact pore structure, their anti-degradation property is improved, and swelling property is reduced. The introduction of hydroxyapatite greatly improved the mechanical properties of hydrogels, but there is no change in the stability and crosslinking network structure of hydrogels. These inorganic phase-enhanced hydrogels were expected to be applied to tissue engineering scaffolds.

Al-based nanocomposite energetic materials have broad application prospects in explosives and propellants, owing to their excellent energy release efficiency. However, their insufficient reliability, poor stability, and difficulty of formation limit their practical application. This study employed self-assembly using a hydrophilic polymer polyvinylpyrrolidone (PVP) together with nano-aluminum powder (Al), copper oxide (CuO), and ammonium perchlorate (AP) to obtain high-strength and high-activity composite micrometer-sized microspheres. The influence of PVP concentration on the mechanical behavior of Al/AP composite microspheres was systematically investigated, and Al was replaced with ultrasonically dispersed Al/CuO to explore the mechanism of action of PVP in the system and the catalytic behavior of CuO. PVP significantly enhanced the interfacial bonding strength. The Al/AP/5%PVP microspheres achieved a strength of 8.4 MPa under 40% compressive strain, representing a 365% increase relative to Al/AP. The Al/CuO/AP/5%PVP microspheres achieved a strength of 10.2 MPa, representing a 309% increase relative to Al/CuO. The mechanical properties of the composite microspheres were improved by more than threefold, and their thermal reactivities were also higher. This study provides a new method for the controlled preparation of high-strength, high-activity, micrometer-sized energetic microspheres. These materials are expected to be applied in composite solid propellants to enhance their combustion efficiency.

Glycidyl azide polymer （GAP） with the advantages of non-volatility and excellent thermal stability is a candidate as a re- placement for nitroglycerine （NG） in a double base propellant. The GAP-NC double base propellants were formulated with GAP and nitrocellulose （NC） fibers. Tensile test and SEM characterization indicated that GAP-NC propellants had a homoge- neous structure. Thermogravimetric analysis of GAP-NC propellants revealed that the onset decomposition temperature reached a high level ranging from 192.9 to 194.6 ℃, which indicated that the substitution of NG with GAP contributed to the safe storage and process operations for double base propellant. The result analysis of decomposition products of GAP-NC propellants showed that the main gas decomposition products of the propellants were NO, NO〉 CO, CO2, NH3, CH4, HCN, N2 CH20 and C2H40. The thermal decomposition process of the specimens was proposed.

Aluminium (Al) powders of micron size are widely applied to energetic materials as a high energy fuel. However, its energy conversion efficiency is generally low due to low oxidation activity. In this paper, a polytetrafluoroethylene (PTFE) coating layer with both protection and activation action was successfully introduced onto the surface of Al via adsorption and following heat treatment. The preparation conditions were optimized and the thermal activity of this core-shell composite material was studied. The potential enhancement mechanism for Al oxidation was proposed. The results showed that PTFE powders deformed into membrane on the surface of Al after the sintering process. This polymer shell could act as an effective passivation layer protecting internal Al from oxidation during aging. The reduction in metallic Al of Al/PTFE was decreased by 84.7%, more than that in original spherical Al when the aging time is 60 days. Moreover, PTFE could react with Al resulting in a thin AlF3 layer, which could promote the destruction of Al2O3 shell. Thus, PTFE could enhance oxidation activity of micro-Al. The conversion of Al was increased by a factor of 1.8 when heated to 1100 °C. Improved aging-resistant performance and promoted oxidation activity of Al could potentially broaden its application in the field of energetic materials.

Iron corrosion is very common in our daily life, and its effective protection can extend its service life. As a small molecule monomer, 2-hydroxyethyl methacrylate phosphate (HEMAP) has a phosphate group that can effectively chelate with iron ions to form a passivation layer (iron phosphate), thus slowing down the corrosion rate of iron. This study synthesized HEMAP-modified acrylic–alkyd resin copolymers with variable concentrations using free radical polymerization. The addition of HEMAP not only increases the cross-linking density of the resin, but it also further strengthens the adhesion between the resins and the iron substrate, which prevents corrosive substances from penetrating the resin. According to electrochemical studies, adding 2% mass fraction of HEMAP to the resin could greatly increase its resistance to corrosion. This study reveals HEMAP’s capacity to enhance the protection of coatings on iron substrates and lengthen the metal’s service life.

The research and development of rocket propellants with a high solid content and superior mechanical and security performance is urgently needed. In this paper, a novel extruded modified double-base (EMDB) rocket propellant plasticized by N-butyl-N-nitratoethyl nitramine (Bu-NENA) was prepared to overcome this challenge. The results indicated that Bu-NENA decreased the mechanical sensitivity successfully, contributing to the mechanical properties against traditional nitroglycerin (NG) based EMDB propellants, while hexogen (RDX), which is beneficial to propellant energy, was not conducive to the elongation and sensitivity of the propellants. By contrast with the blank group (NG-based EMDB propellant, R0), the elongation of the optimized propellant at −40 °C was promoted by 100% from 3.54% to 7.09%. Moreover, the β-transition temperature decreased from −33.8 °C to −38.1 °C due to superior plasticization by Bu-NENA, which represents a better toughness. The friction sensitivity dropped by 100% from 46% to 0%. Simultaneously, the height for 50% probability of explosion (H50) increased by 87.2% from 17.2 cm to 32.2 cm. The results of this research could be used to predict a potential prospect in tactical weapons.

Waterborne coatings have obtained more and more attention from researchers with increasing concerns in environmental protection, and have the advantages of being green, environmentally friendly and safe. However, the introduction of hydrophilic groups leads to lower hydrophobicity and it is difficult to meet the requirements of complex application environments. Herein, we proposed an optimization approach of waterborne polyurethane (WPU) with vinyl tris(β-methoxyethoxy) silane (A172), and it was found that the surface roughness, mechanical properties, thermal stability and water resistance of WPU will be increased to a certain extent with the addition of A172. Moreover, the hydrophobicity of the coating film is best when the silicon content is 10% of the acrylic monomer mass and the water contact angle reaches 100°, which could exceed two-thirds of the research results in the last decade. Therefore, our study can provide some theoretical basis for the research of hydrophobic polyurethane coatings.

The relatively poor mechanical properties of extruded modified double base (EMDB) propellants limit their range of applications. To overcome these drawbacks, a novel method was proposed to introduce glycidyl azide polymer-based energetic thermoplastic elastomers (GAP-ETPE) with bonding groups into the propellant adhesive. The influence of the molecular structure of three kinds of elastomers on the mechanical properties of the resultant propellant was analyzed. It was found that the mechanical properties of the propellant with 3% CBA-ETPE (a type of GAP-ETPE that features chain extensions using N-(2-Cyanoethyl) diethanolamine and 1,4-butanediol) were improved at both 50 °C and −40 °C compared to a control propellant without GAP-ETPE. The elongation and impact strength of the propellant at −40 °C were 7.49% and 6.58 MPa, respectively, while the impact strength and maximum tensile strength of the propellant at 50 °C reached 21.1 MPa and 1.19 MPa, respectively. In addition, all three types of GAP-ETPE improved the safety of EMDB propellants. The friction sensitivity of the propellant with 3% CBA-ETPE was found to be 0%, and its characteristic drop height H50 was found to be 39.0 cm; 126% higher than the traditional EMDB propellant. These results provide guidance for studies aiming to optimize the performance of EMDB propellants.

The safe storage time for double base propellant (DBP or DB propellant) with stabilizers could usually be calculated to be greater than 40 years. However, the actual service life is far below that, which is largely caused by the decline of propellant mechanical performance. In this work polytetrafluoroethylene (PTFE) was introduced into the double base propellant formula as an additive. The tensile properties of this propellant before and after artificial aging were determined. The evaporation and diffusion characteristics of nitroglycerin (NG) in propellant were evaluated by thermogravimetry analysis (TGA). The results showed that mechanical properties of propellant were improved due to PTFE, especially for elongation at −40 °C, which was greatly increased by 115%. Moreover, the results of TGA showed that NG migration was reduced due to PTFE, which delayed the decline of propellant mechanical performance during aging. The reduction in elongation at −40 °C caused by aging was decreased by 68.5% for PTFE modified DBP. Enhanced mechanical properties and reduced NG migration could potentially prolong propellant service life.

The function of the aromatic and neutral amino acid transporter gene ANT1-like ( NtANTL2 ) was investigated. NtANTL2-3 over-expressor plants displayed greater tolerance to high nitrogen application compared to WT plants, characterized by better growth. As for carbon metabolism, the activity of sucrose phosphate synthetase in overexpression lines was 1.5 times higher than that in wild-type plants at 0.1% nitrogen, while sucrose synthase activity was significantly lower under all nitrogen levels. These changes in enzyme activities were closely associated with the differential gene expressions of GBSSI ( granule—bound starcsssh synthase I ), SUS ( sucrose synthase ), INV ( invertase ), and SPS ( sucrose phosphate synthase ). The activities and gene expressions of key enzymes in nitrogen metabolism like nitrate reductase, glutamine synthetase, glutamate synthase, and glutamate dehydrogenase were also significantly affected. The GDH activity in overexpression lines was increased by 2.4-fold and 4.3 fold at 0.1% and 0.3% nitrogen, respectively. Increased levels of multiple amino acids besides aspartic acid content were found in NtANTL2 overexpression plants. These results clearly indicate the regulatory ability of NtANTL2 on amino acid composition and its central role in coordinating carbon and nitrogen metabolism balance.