Amorphous polyamide coating resins from sugar-derived monomers

In this article, the synthesis of bio-based polyamides for powder coating applications and their evaluation in a solventborne coating system are reported. The M _n values of the resins were between 3000 and 4000 g mol^?1 and the resins displayed T _g values from 60 to 80°C. Both amine and carboxylic acid functionalities (total ~0.6 mmol g^?1) were introduced for curing purposes. The resins were cured with triglycidyl isocyanurate (TGIC) or N,N,N′,N′-tetrakis(2-hydroxyethyl)adipamide (Primid XL-552). The curing reaction was followed using rheology which indicated that TGIC achieved higher reaction rates and higher gel contents. The DSC analysis of the cured disks showed that all cured samples were amorphous as is desired for the targeted coating application. The resins required a curing temperature higher than 150°C. Aluminum panels were coated using a solventborne approach and the coatings were cured at 180°C during 1 h. Dewetting was observed on all panels. Network formation was adequate for an amine-functional resin cured with TGIC as indicated by solvent resistance testing. In conclusion, the developed bio-based polyamide resins are promising materials to be used as binder resins in powder coating applications.     

A new extra situ sol–gel route to silica/epoxy (DGEBA) nanocomposite. A DTA study of imidazole cure kinetic

Silica nanoparticles were obtained through the Stöber method, from mixtures of tetraethoxysilane (TEOS) and 3-aminopropyltriethoxysilane (APTS). The nanoparticles were dispersed in tetrahydrofuran (THF) and coupled to bisphenol A epoxy resin (DGEBA) through surface amino groups. After removing THF non-isothermal cure was performed at different heating rates (2–20°C/min), using imidazole (2–4 wt%) as curing agent. For the sake of comparison bare DGEBA epoxy polymers were also prepared with similar schedule A nanocomposite of well-dispersed silica nanoparticles (5 wt%) in a fully cured epoxy matrix was easily obtained. Lower cure kinetics were observed with silica addition. This was attributed to reduction of the imidazole volume concentration. Cure activation energy was not influenced by silica presence, whereas it changed with the imidazole content. Therefore, experimental results suggested that silica had only an indirect effect (the reduction of the imidazole molar concentration) on the epoxy matrix cure kinetics. Glass transformation temperatures, T _g, as high as 175°C were recorded. The nanocomposite glass transformation temperature depended on the heating rate of the cure process, the imidazole and silica content. T _g changes as high as 40°C were detected as a function of the heating rate. At higher imidazole content no differences in T _g values between bare polymer and the nanocomposite were observed. This suggests that a higher imidazole content assures a better interconnection between the compatibilizing epoxy shell around the nanoparticles and the epoxy matrix. The new proposed methodology is an easy route to engineer both nanocomposites structure and interfacial interactions, thus tailoring their properties.     

Laponite-graphene oxide hybrid particulate filler enhances mechanical properties of cross-linked epoxy

A new hybrid of Laponite and graphene oxide (LGO), prepared in aqueous media by ultrasonication followed by solvent evaporation was used to reinforce epoxy matrix. The hybrid system was dispersed in liquid epoxy using a two-step solvent-assisted process. The suspensions showed negligible enhancements in processing barrier as revealed by rheology. A combinatorial analysis of small-angle x-ray scattering (SAXS) and microscopy suggested uniform dispersion of nanofillers in the matrix. The fillers showed fractal dimensions in polymer matrix as inferred from SAXS studies. Below 0.5 wt% LGO, the structure showed surface fractal and above 0.5 wt% the composites showed mass fractal, indicating a transformation from well-dispersed to agglomerated composites as the filler content increases. The composites exhibited substantial improvements in various mechanical properties. Notably, the flexural strength and modulus increased by ~23% and ~29%, respectively, with only 0.5 wt% LGO and the fracture toughness showed an increment of ~23% with 0.3 wt% LGO in epoxy matrix. A bimodal distribution of glass transition temperature (T _g ) with improved T _g was obtained for the composites. The simultaneous strengthening and toughening effects of nanofillers are explained by means of fractography.     

Improvement of UF/fiberglass mat properties used in roofing shingles through emulsion polymers and nanoclay addition

Modification of urea–formaldehyde (UF) resin binder for making fiberglass mats was aimed as a route to enhance its brittleness and improve its mechanical properties. The UF resin modifiers were chosen among pure acrylate emulsion polymers having different glass transition temperatures (T _g). Blends of 10% w/w based on dry modifiers and UF resin were prepared. The most effective modifier was chosen and 4 wt% of nanoclay was added to the UF resin for improvement of its mechanical properties. Morphologies of the fractured surface of the UF-modified films were investigated by scanning electron microscopy (SEM). Coarser texture of the fractured surface was regarded as an increased toughness of the modified UF resin. Investigation of gel time at 100 °C on various modified urea–formaldehyde resins showed that the gel time of the modified UF resins generally decreases with adding polymeric emulsions. It is decreased further when less film forming latex (higher T _g) is used in UF resin. Less film formation on the other hand, promotes easier water release during UF resin curing. Tensile and tear strength of the fiberglass mat composites have been increased up to 300 and 50%, respectively, while additional increase of 33% in tensile strength was obtained when nanoclay was incorporated into the composites. X-ray diffraction (XRD) analysis and Si-mapping through SEM were employed in order to show the dispersion and the distribution of nanoclay in the composites, respectively. The disappearance of the peak at 2θ = 7.22 confirmed the exfoliation of the employed nanoclay.     

Curing kinetics of epoxy cured by cardanol-based phenalkamines synthesized from different polyethylenepolyamines by Mannich reaction

Phenalkamines with different structures are expected to affect the curing reaction of epoxy, yet the exact mechanism remains to be elucidated. In this study, four cardanol-based phenalkamines (named PK1, PK2, PK3, and PK4, respectively), synthesized from ethylenediamine, diethylenetriamine, triethylenetetramine, and pentaethylenehexamine, were used as curing agents in diglycidyl ether of bisphenol A (DGEBA) epoxy system. The phenalkamines were characterized by Fourier transform infrared spectroscopy, nuclear magnetic resonance, and time-of-flight secondary ion mass spectrometry. The curing behaviors and kinetics were investigated by non-isothermal differential scanning calorimetry, and the activation energies of the reactions (E _α ) were determined using Kissinger–Akahira–Sunose (KAS) and Starink methods. The results indicate a similar curing mechanism for all four phenalkamines. All E _α values remain almost constant in the range of 0.05 ≤ α ≤ 0.6, and increase dramatically after α > 0.6 due to greater viscosity of the reaction systems. The diffusion of reactive groups plays an increasingly important role in determining the curing kinetics. In addition, DGEBA/PK1 and DGEBA/PK2 have lower initial E _α values than DGEBA/PK3 and DGEBA/PK4, because PK1 and PK2 have lower viscosity than PK3 and PK4. When α is high, DGEBA/PK1 and DGEBA/PK2 have higher E _α values than DGEBA/PK3 and DGEBA/PK4, because more tertiary amine groups can be formed in the reactions between the epoxy and secondary amine groups in the DGEBA/PK3 and DGEBA/PK4 systems, which catalyze the curing reaction and it thus lowers energetic barrier.     

Mild-thermal fabrication and phase conformation of chopped glass fiber-reinforced low-density unsaturated polyester resin with NH<Subscript>4</Subscript>HCO<Subscript>3</Subscript>

Chopped glass fiber-reinforced low-density unsaturated polyester resin product (CFR-LDUPRP) was fabricated utilizing chopped glass fiber and ammonium bicarbonate through an innovative mild-thermal process featuring an ideal phase conformation. Based on the mild-thermal mechanism and preliminary experiments, an orthogonal experiment was conducted to obtain the optimal conditions of CFR-LDUPRP fabrication. The optimal fabrication temperature of 76.0 °C, 20.00 phr of 3 mm chopped glass fiber, 2.50 phr of NH₄HCO₃ and 1.50 phr of tert-butylperoxy benzoate (TBPB) comprised the optimal conditions for CFR-LDUPRP fabrication. Under this condition, the density (ρ), compressive strength (P), and specific compressive strength (P_s) of CFR-LDUPRP specimen were 0.63?±?0.02 g cm^??3, 24.29?±?0.73 MPa, and 38.56?±?1.02 MPa g^??1 cm³, in the given order. The analyses of nonisothermal DSC and semi-quantitative FTIR revealed that NH₄HCO₃ neutralized the residual acid in the resin, leading to an early polymerization of resin and a prolonged curing process of UPR. The endothermic decomposition of NH₄HCO₃ and the vaporization of water enabled a mild-thermal mechanism, which was beneficial for the growth of bubbles and for the distribution of chopped glass fiber in the resin. Proper phase conformation of the resin, bubbles, chopped glass fiber together with cracks and microvoids in the resin matrix, characterized by SEM and ¹H NMR, facilitated the polymerization of UPR and improved properties of CFR-LDUPRP. Bubbles diameter ranged from 0.27 to 0.61 mm without linking or destroyed bubbles.     

Fabrication of thermally stable porous films from a cured epoxy resin via the <Emphasis Type="Italic">Breath Figures</Emphasis> process

In the current work, porous films based on epoxy resin have been obtained via the Breath Figures method. It was shown that the use of a low-temperature curing agent and fluoro-containing organosilicon copolymer, compatible with epoxy resin, makes it possible to obtain porous, thermostable, highly hydrophobic coatings with a pore diameter of 3–4 µm. When the epoxy resin/copolymer mixture is homogenous, the modifier prevents water droplet coalescence; otherwise, the mixture becomes heterogeneous, and the positive influence of the modifier is lost. The obtained modified porous films are highly hydrophobic and maintain their porous structure until polymer devitrification occurs. The simplicity of the Breath Figures method shows great potential for the manufacture of water-repellent paint coatings based on epoxy resin for use in a variety of applications.     

A coarse-grained model for polylactide: glass transition temperature and conformational properties

In this article, we present a coarse-grained (CG) model of poly(lactic acid) (PLA) developed by the iterative Boltzmann inversion (IBI) method. The coarse-grained potential was derived by matching the structural probability distribution functions to those of reference atomistic simulation. The resulting coarse-grained potential was found to be temperature-dependent when trying to reproduce the thermal expansion behavior of PLA. To satisfactory reproduce this behavior, the potential needs to be modified by a temperature factor of (T/T ₀)^0.3; T ₀ = 327 K is the temperature at which the potential has been derived. The glass transition temperature (T _g) as predicted by the modified CG potential compared favorably with those from experiment and atomistic simulation. Chain conformational properties were also evaluated in terms of a chain length (N)-radius of gyration (R _g) relation and the persistence length. The model we develop was also noted to provide a considerable speed-up of computer time compared to its atomistic counterpart.     

Sonocrystallization of Interesterified Fats with 20 and 30% of Stearic Acid at the sn-2 Position and Their Physical Blends

Physical blends (PB) of high oleic sunflower oil and tristearin with 20 and 30% stearic acid and their interesterified (IE) products where 20 and 30% of the fatty acids are stearic acid at the sn-2 position crystallized without and with application of high intensity ultrasound (HIU). IE samples were crystallized at supercooling temperatures (ΔT) of 12, 9, 6, and 3 °C while PB were crystallized at ΔT = 12 °C. HIU induced crystallization in PB samples, but not in the IE ones. Induction in crystallization with HIU was also observed at ΔT = 6 and 3 °C for IE C18:0 20 and 30% and at ΔT = 9 °C only for the 30% samples. Smaller crystals were obtained in all sonicated samples. Melting profiles showed that HIU induced crystallization of low melting triacylglycerols (TAGs) and promoted co-crystallization of low and high melting TAGs. In general, HIU significantly changed the viscosity, G′, and G″ of the IE 20% samples except at ΔT = 12 °C. While G′ and G″ of IE 30% did not increase significantly, the viscosity increased significantly at ΔT = 9, 6, and 3 °C from 1526 ± 880 to 6818 ± 901 Pa.s at ΔT = 3 °C. The improved physical properties of the sonicated IE can make them good contenders for trans-fatty acids replacers.     

High-refractive quinolinone-based polymers for ophthalmic devices

Seven novel high refractive index (HRI) acrylic monomers, comprising the quinolinone structural motive, have been synthesized and characterized. Cross-linked homo- as well as copolymers were prepared by photochemical bulk polymerization. The homopolymers show refractive indices at 589 nm (n ₅₈₉) ranging from 1.60 up to 1.68, glass transition temperatures (T _g) from 52 to 76 °C, and Abbe numbers (ν _Abbe) of 19 to 25. Due to these parameters, the homopolymers are not suitable to be used directly for intraocular lens (IOL) manufacture, but the quinolinone monomers may be used as high refractive index components in copolymers. Potential mixtures were calculated theoretically and one example, a copolymer with PEA and PEGPEA, was prepared and characterized. The experimentally found values were T _g?=?24 °C, n ₅₈₉?=?1.593, and ν _Abbe?=?28.3. Interestingly, the quinolinone compound which does not have any spacer between the polymerizable group and the high refractive index group appears to be the most useful one. The lightfastness of the new material fulfills the demands for IOLs. Quinolinone derivatives are promising new comonomers for high refractive index copolymers.     

Soybean oil-based thermoset reinforced with rosin-based monomer

A full bio-based cured resin was synthesized by copolymerization of acrylated-epoxidized soybean oil (AESO) and 2-acrylamidoethyl dehydroabietic acid (DHA-HEMAA). The rigid rosin-based monomer 2-acrylamidoethyl dehydroabietic acid was first prepared from dehydroabietic acid and N-hydroxyethylacrylamide, which was characterized by nuclear magnetic resonance and Fourier transform infrared (FTIR) spectrometry techniques. The cured resin was then synthesized and characterized by FTIR spectroscopy, differential scanning calorimetry, dynamic thermomechanical analysis, and thermogravimetric analysis, as well as using a Kruss tensiometer and a universal testing machine. The results indicated that the resin cured with rosin-based monomer exhibited excellent thermomechanical properties. The crosslink density and thermal stability of cured samples containing DHA-HEMAA at molar ratio between 10 and 30% were higher than those of AESO/DHA-HEMAA0 sample. With increasing DHA-HEMAA content, the glass transition temperature (T_g), elongation-at-break, and tensile strength of samples increased, in the stated order, from 16 to 38 °C, from 24 to 45.8%, and from 1.7 to 6.5 MPa. Due to DHA-HEMAA with a hydrophenanthrene structure, the θ values increased with the increase of DHA-HEMAA molar ratios. The full bio-based rosin thermosetting resins may have great potentials in practical application fields, such as coating, adhesive, and packaging materials.     

Synthesis and characterization of polyimides from 4,4′-(3-(<Emphasis Type="Italic">tert</Emphasis>-butyl)-4-aminophenoxy)diphenyl ether

A novel diamine 4,4′-(3-(tert-butyl)-4-aminophenoxy)diphenyl ether (4) was synthesized from 2-tert-butylaniline and 4,4′-oxydiphenol through iodination, acetyl protection, coupling reaction and deacetylation protection. Then some polyimides (PIs) were obtained by one-pot polycondensation of diamne 4 with several commercial aromatic dianhydrides respectively. They all exhibit enhanced solubility in organic solvents (such as NMP, DMF, THF and CHCl₃ etc.) at room temperature. Their number-average molecular weights are in the range of (2.1–3.7)?×?10⁴ g/mol with PDI from 2.25 to 2.74 by GPC. They can form transparent, tough and flexible films by solution-casting. The light transparency of them is higher than 90% in the visible light range from 400 nm to 760 nm and the cut-off wavelengths of UV–vis absorption are below 370 nm. They also display the outstanding thermal stability with the 5% weight loss temperature from 525 °C to 529 °C in nitrogen atmosphere. The glass transition temperatures (T _g s) are higher than 264 °C by DSC. XRD results demonstrate that these PIs are amorphous polymers with the lower water absorption (<0.66%). In summary, the incorporation of tert-butyl groups and multiple phenoxy units into the rigid PI backbones can endow them excellent solubility and transparency with relatively high T _g s.     

Buckypapers of 4,4′-oxydianiline-modified polyvinylchloride and functional nano-filler obtained by resin infusion method

This study provides information on the fabrication and characterization of polyvinylchloride (PVC) buckypaper composite using resin infusion method. PVC modified with 4,4′-oxydianiline (ODA) was infiltrated through buckypapers made of purified multi-walled carbon nanotubes (P-MWCNTs) and functionalized MWCNTs (F-MWCNTs). The increases in P-MWCNT and F-MWCNT contents were investigated on the physical properties of BP-PVC-ODA/PEG (polyethylene glycol)/P-MWCNT and BP-PVC-ODA/PEG/F-MWCNT buckypaper composites. Fourier transform infrared spectroscopy was used for the functional group confirmation which proved the PVC modification and functionality of MWCNTs. The scanning electron micrographs of BP-PVC-ODA/PEG/F-MWCNT showed that intercalation of cross-linked polymer with nanotube produced a polymer-coated F-MWCNT mesh. The maximum degradation temperature (T _max) of functional composite BP-PVC-ODA/PEG/F-MWCNT 0.05 (484 °C) was higher than that of non-functional BP-PVC-ODA/PEG/P-MWCNT 0.05 (473 °C). The glass transition temperature (T _g) of BP-PVC-ODA/PEG/F-MWCNT 0.05 was 225 °C, while BP-PVC-ODA/PEG/F-MWCNT 0.03 yielded a lower T _g of 214 °C. Tensile strength of the functional buckypaper was also found to increase to 37.3 MPa with filler loading. According to X-ray diffraction, the amorphous character of buckypaper showed a trend towards crystal formation with filler loading. P-MWCNT-based buckypaper showed an electrical conductivity up to 4.12 × 10^?1 S/cm; lower than the electrical conductivity of functional buckypaper (1.98 S/cm). The results demonstrated that the resin infusion technique was a successful method to achieve high performance buckypapers compared with F-MWCNTs.     

Green Nanosilver as Reinforcing Eco-Friendly Additive to Epoxy Coating for Augmented Anticorrosive and Antimicrobial Behavior

Epoxy resin GY250 representing diglycidyl ethers of bisphenol-A (DGEBA) was reinforced with 1, 3 and 5wt % of surface functionalized silver nanoparticles (F-AgNPs) which were synthesized using Couroupita guianensis leaves extract with a view of augmenting the corrosion control property of the epoxy resin and also imparting antimicrobial activity to epoxy coatings on mild steel. Corrosion resistance of the coatings was evaluated by EIS, potentiodynamic polarization studies and cross scratch tests. AFM, SEM, HRTEM and EDX were utilized to investigate the surface topography, morphology and elemental composition of the coatings on MS specimens. Results showed that the corrosion resistance, hardness and T_g of the DGEBA/F-AgNPs coatings increased at 1wt % of F- AgNPs. The DGEBA/F-AgNPs coatings also offered manifold antimicrobial protection to the MS surfaces by inhibiting the growth of biofilm forming bacteria like P. aeruginosa, B. subtilis, the most common human pathogen E. coli and the most virulent human pathogenic yeast C. albicans.     

Investigation of the fast relaxation in glass-forming selenium by low-frequency Raman spectroscopy

The low-frequency Raman spectra of liquid and vitreous selenium are investigated. It is demonstrated that the temperature dependence of the intensity of the fast relaxation at the glass transition temperature (T _g = 308 K) exhibits a specific feature. This feature manifests itself in a sharper increase in the intensity at temperatures T > T _g as compared to that observed at lower temperatures. The intensities of the fast relaxation at the critical temperature T _c are evaluated by the extrapolation of the linear dependence to the temperature range T > T _g in the framework of the mode-coupling theory. The new results obtained for selenium are compared with the available data for other glass-forming materials (boron oxide, toluene, arsenic sulfide). It is shown that, for all the glasses under investigation, the parameter describing the contribution of the fast relaxation to the Raman spectrum takes on the same value at the critical temperature T _c and is approximately equal to 0.3.     

Novel amphiphilic temperature responsive graft copolymers PCL-<Emphasis Type="Italic">g</Emphasis>-P(MEO<Subscript>2</Subscript>MA-<Emphasis Type="Italic">co</Emphasis>-OEGMA) via a combination of ROP and ATRP: synthesis,characterization, and sol-gel transition

A series of well-defined novel amphiphilic temperature-responsive graft copolymers containing PCL analogues P(αClεCL-co-εCL) as the hydrophobic backbone, and the hydrophilic side-chain PEG analogues P(MEO₂MA-co-OEGMA), designated as P(αClεCL-co-εCL)-g-P(MEO₂MA-co-OEGMA) have been prepared via a combination of ring-opening polymerization (ROP) and atom transfer radical polymerization (ATRP). The composition and structure of these copolymers were characterized by ¹H NMR and GPC analyses. The self-assembly behaviors of these amphiphilic graft copolymers were investigated by UV transmittance, a fluorescence probe method, dynamic light scattering (DLS) and transmission electron microscopy (TEM) analyses. The results showed that the graft copolymers exhibited the good solubility in water, and was given the low critical temperature (LCST) at 35(±1) °C, which closed to human physiological temperature. The critical micelle concentrations (CMC) of P(αClεCL-co-εCL)-g-P(MEO₂MA-co-OEGMA) in aqueous solution were investigated to be 2.0 × 10^?3, 9.1 × 10^?4 and 1.5 × 10^?3 mg·mL^?1, respectively. The copolymer could self-assemble into sphere-like aggregates in aqueous solution with diverse sizes when changing the environmental temperature. The vial inversion test demonstrated that the graft copolymers could trigger the sol-gel transition which also depended on the temperature.     

Hydrolytic Activity of Castor Bean Powder: Effect of Gum Arabic,Lipase and Oil Concentrations

Lipase activity from castor bean seed powders was evaluated in hydrolysis reactions at 37 °C. The effects of different concentrations of lipase powder (LP), substrate (high oleic sunflower oil, O) and surfactant (gum arabic, A) on lipase activity (R) were assessed using experimental designs. Considered variable bounds were: 0.05–0.15 g_LP, 0.07–0.20 oil:aqueous phase (w/w) and 0–0.025 g gum arabic/mL. All variables had significant effects on the transformed response, R ^1/2. The most important result was the negative effect of gum arabic in lipase activity, even when high oil concentrations were used. Experimental lipase activities involved in this work were within 0.32–16.90 mmol_FFA/g_oil·g_LP·h. Using 0.05 g_LP and 0.20 oil:aqueous phase (w/w) without gum arabic, the activity of 20.47 ± 7.19 mmol_FFA/g_oil·g_LP·h was reached.     

Preparation of high surface area mesoporous nickel oxides and catalytic oxidation of toluene and formaldehyde

Mesoporous nickel oxide (NiO) nanoparticles were synthesized by the thermal decomposition reaction of Ni(NO₃)₂·9H₂O using oxalic acid dihydrate as the mesoporous template reagent. The pore structure of nanocrystals could be controlled by the precursor to oxalic acid dihydrate molar ratio, thermal decomposition temperature and thermal decomposition time. The structural characteristic and textural properties of resultant nickel oxide nanocrytals were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), N₂ adsorption–desorption isotherm and temperature programmed reduction. The results showed that the most excellently mesoporous nickel oxide particles (m-Ni-1-4) with developed wormlike pores were prepared under the conditions of the mixed equimolar precursor and oxalic acid and calcined for 4 h at 400 °C. The specific surface area and pore volume of m-Ni-1-4 are 236 m² g^?1 and 0.42 cm³ g^?1, respectively. Over m-Ni-1-4 at space velocity = 20,000 mL g^?1 h^?1, the conversions of toluene and formaldehyde achieved 90 % at 242 and 160 °C, respectively. It is concluded that the reactant thermal decomposition with oxalic acid assist is a key step to improve the mesoporous quality of the nickel oxide materials, the developed mesoporous architecture, high surface area, low temperature reducibility and coexistence of multiple oxidation state nickel species for the excellent catalytic performance of m-Ni-1-4.     

Cyanate ester resin modified by phenolic resin containing diphenyl oxide segments with high molecular weight

To obtain modified cyanate ester (CE) with good comprehensive properties and low cost, a novel phenolic resin containing diphenyl oxide (MPF) with high molecular weight was synthesized from diphenyl ether, formaldehyde, methanol and phenol by a two-step process which differed from polyphenylene oxide (PPO) in structure. The curing reaction and properties of the modified 2,2-bis(4-cyanatophenyl) propane (bisphenol-A-based cyanate ester, BADCy) by MPF were investigated. It was found that the curing temperature of the modified CE was lower than that of the unmodified CE. When the ratio of MPF and BADCy was 3:7, the cured resin exhibited low dielectric constant (3.00), low dielectric loss (0.0062) and high impact strength (12.5 kJ/m²), and its T _d5% was 371 °C, being superior to CE in the comprehensive properties. When the content of MPF was above 30 %, MPF/BADCy had poor comprehensive properties. In order to improve MPF/BADCy with high content of MPF, epoxy resin (E51) was added. When the ratio of MPF, BADCy and E51 was 50:50:67, the cured resin exhibited low dielectric constant (2.96), dielectric loss (0.0078) and high impact strength (11.84 kJ/m²), and its T _d5% was 365 °C. Small content of MPF or the combination of E51 and MPF were good for BADCy to improve its comprehensive properties.     

Ignition of a metallized composite solid propellant by a group of hot particles

The solid-state ignition of a metallized composite propellant (ammonium perchlorate + 14% butyl rubber +5% aluminum powder + 6% plasticizer) under local heating by several sources of limited power capacity (dimensions of the hot particle x _p = 4 mm and y _p = 2 mm) was studied by mathematical modeling. For the temperature of the heated steel particles and the distance between them varied in the ranges 700 < T _p < 1500 K and 0.1_{x p} < Δ_x < 1.5xp, respectively, the values of T _p and Δ_x were determined for which the ignition delay corresponds to the initiation of combustion of the composite propellant by a single particle, by a plate at a constant temperature or by several particles. In the region of low initial temperatures of the local sources (T _p < 1100 K), the limiting values Δ_x → 0.1x _p and Δ_x > 1.5x _p, were identified for which the characteristics and mechanism of ignition of the propellant by a group of heated particles can be studied using the “plate–propellant–gas” model and the “single particle–propellant–gas” model, respectively. Decreasing the distance Δx at T _p < 1100 K decreases the induction period to 50% and reduces the minimum initial temperature of the source required to initiate propellant combustion from 830 to 700 K. At T _p > 1100 K, the ignition of the metallized composite solid propellant by a single or several particles can be studied using relatively simple one-dimensional models of condensed material ignition by a plate at constant temperature. The variation in the ignition delay in this case is less than 5%.