Synergistic enhancement of heat resistance and mechanical performance of epoxy resin by introducing entanglement effect

The azido propellant, with high energy and low signature, has been a hotpot in the field of propellants. However, the risk of low heat resistance and mechanical performance restricts their range of applications in high-energy formulations. In this study, four azido propellants based on 3,3-bis (azidomethyl) oxetane-tetrahydrofuran copolyether (BAMO-THF) have been prepared, their basic physical properties including energetic properties, internal micro-structure and true density were studied; their tensile properties, dynamic mechanical performances, were investigated, the structure-properties relationship was proposed. The results demonstrate that the obtained propellant shows an elastomeric composite material behavior, with an obvious relaxation in the initial stage and susceptibility to loading condition. The formula structure not only causes obvious difference in the second stage of relaxation, but also strongly affects the initial stage, which is quite different from the influence of testing condition. Besides, the low temperature toughness of the azido propellant is improved by using diol partly replaces diamine as a chain extender, but their stress modulus drop down obviously, leading to the notable stress relaxation behavior at high temperatures. It was found that the improvement of the ordering degree of microstructure or network integrity could restrict the stress relaxation, which was an effective approach to improve the heat resistance and mechanical performance of azido propellant at high temperatures.

Simultaneously improved heat-resistance and mechanical performance of core/shell-structure poly (butyl acrylate)/poly (acrylonitrile-styrene) using poly (α-methylstyrene-acrylonitrile)

ABSTRACTIn this work, use of myo‐inositol as a biobased nucleating agent (NA) for PLLA was researched. Effects of myo‐inositol on non‐isothermal and isothermal crystallization behaviors of PLLA at temperatures ranged from 85 °C to 130 °C were studied by using DSC, POM and WAXD. Isothermal crystallization kinetics results showed that the incorporation of myo‐inositol enhanced significantly the crystallization rate of the PLLA samples. It was confirmed that the optimum isothermal crystallization temperature range was 100 to 110 °C. The above results were instructive to confirm proper heat treatment time and temperature for compression or injection molding to fabricate highly crystallized PLLA articles. The relations among heat treatment time, crystallinity, heat resistance, and mechanical performances of the neat PLLA and PLLA/1% myo‐inositol specimens prepared by compression molding were investigated. Compared with the PLLA specimens, the PLLA/1% myo‐inositol specimens showed a shorter heat treatment time to reach the maximum crystallinity. Vicat softening temperature, as well as tensile strength, modulus, and toughness of the PLLA/1% myo‐inositol specimens was improved when crystallinity increased from 5.4% to 38.1%. Considering the nontoxicity and biocompatibility of myo‐inositol, PLLA/myo‐inositol blends would be potential to prepare some products, which are required higher health standard and can be used in elevated temperature environments. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44732.

Entirely environment-friendly polylactide composites with outstanding heat resistance and superior mechanical performance fabricated by spunbond technology: Exploring the role of nanofibrillated stereocomplex polylactide crystals

Role of graphene oxide infusion in concrete to elevate strength and fire performance in construction concrete

Effect of poly(lactic acid) crystallization on its mechanical and heat resistance performances

Designing multi-aromatic ring epoxy composites to integrate high insulation and high heat resistance performances by electron-induced effect

Potential ergogenic aid of capsaicinoid or capsinoids in healthy adults: a systematic review with meta-analysis.

Enhancement of heat resistance and waterproof performance of combustible cartridge cases with phenolic epoxy resin-modified polydimethylsiloxane composite coating

Tetraglycidyl diamino diphenyl methane (TGDDM) and its carbon fiber composite are widely studied and used because of their heat resistance and high performance. In order to obtain efficient reinforcing effects in a simple manner, we adopt the idea of molecular composite—uniformly dispersing the rigid‐rod macromolecules in the TGDDM matrix. Herein, we prepared fully aminated‐poly(p‐phenylene terephthalamide) by direct polycondensation and hydrogenation reduction as the reinforcing agent. The fully aminated‐PPTA is distributed uniformly in the cross‐linked epoxy resin (EP) network by chemical bonds, and achieves efficient reinforcement. With the addition of only 0.5 wt% fully aminated‐PPTA, the tensile strength and Young's modulus of EP are improved to 127.7 ± 7.4 MPa (+28%) and 3.36 ± 0.15 GPa (+44%); the flexural strength and modulus are improved to 209.6 ± 9.4 MPa (+42%) and 3.70 ± 0.14 GPa (+37%); the notch impact strength is improved by 32%. Crucially, the heat resistance of EP almost remains unchanged. Furthermore, the flexural properties and interlaminar shear strength of the carbon fiber composite are also comprehensively increased. Compared with other modified fillers, the fully aminated‐PPTA is simple to prepare and blend, and is an efficient reinforcing agent for TGDDM and its carbon fiber composite benefitting from its rigid‐rod main chain and amino side groups.Highlights Molecular composite can achieve excellent strengthen and toughen effects. Fully aminated‐PPTA is embedded uniformly in EP network by chemical bonds. TGDDM is effectively reinforced without deteriorated heat resistance. Fully aminated‐PPTA is also a comprehensive reinforcement for EP/CF composite.

Synergetic improvement of flame retardancy and heat resistance of cationic waterborne polyurethanes by introducing a DOPO-containing flame retardant

Sustainable glucose-based phenolic resin and its curing with a DGEBA epoxy resin

The subject of this study was an experimental confirmation of stability of composite nanostructured gypsum silicate binder (CNGSB) system under high-temperature exposure (up to 1000 °C). The hypothesis of the heat-resistance performance of gypsum-based binder was crystallization process in CNGSB system involving a silicate constituent as a reactive component in NB. XRD and DTA analyses demonstrated that thermal exposure of CNGSB to wide range of temperatures of 20–1000 °C leads to α-quartz to β-quartz phase transformation in the binder; amorphous alkali-aluminosilicate (gel) changes to crystal phase of Са-albite. The calculation of cell volumes characteristics for low-temperature (before thermal exposure) and high-temperature (after thermal exposure) phases was performed. The calculated ratios of unit cell volumes were close to 1 which ensures a structural stability of the GNB under thermal exposure and confirms its heat-resistant performance.

Profound understanding of relationships between molecular networks with properties can make it more convenient for people to prepare and employ shape memory polymers (SMPs). In this paper, a series of epoxy SMPs were developed based on epoxy (E‐51), trimethylolpropane tris(3‐mercaptopropionate) and pentaerythritoltetrakis (3‐mercaptopropionate), and 2‐methylimidazole, through “epoxy‐thiol” click reaction. The effect of networks on key properties (heat resistance and mechanical properties shape recovery performance) was systematically investigated. Experiment results indicated that there were positive correlations between network regularity with both thermal–mechanical properties and heat resistance. In addition, regularity of network structure had an effect to restrict shape recovery speed.

Strategies and techniques for improving heat resistance and mechanical performances of poly(lactic acid) (PLA) biodegradable materials