Functional dendritic curing agent for epoxy resin: Processing, mechanical performance and curing/toughening mechanism

2018 ◽  
Vol 136 ◽  
pp. 20-27 ◽  
Author(s):  
Chunhua Lou ◽  
Xijun Liu
2009 ◽  
Vol 114 (5) ◽  
pp. 2706-2710 ◽  
Author(s):  
Y. Yang ◽  
Gong Chen ◽  
K. M. Liew
Keyword(s):  

2021 ◽  
Vol 5 (7) ◽  
pp. 191
Author(s):  
Yanshuai Wang ◽  
Siyao Guo ◽  
Biqin Dong ◽  
Feng Xing

The functionalization of graphene has been reported widely, showing special physical and chemical properties. However, due to the lack of surface functional groups, the poor dispersibility of graphene in solvents strongly limits its engineering applications. This paper develops a novel green “in-situ titania intercalation” method to prepare a highly dispersed graphene, which is enabled by the generation of the titania precursor between the layer of graphene at room temperature to yield titania-graphene nanocomposites (TiO2-RGO). The precursor of titania will produce amounts of nano titania between the graphene interlayers, which can effectively resist the interfacial van der Waals force of the interlamination in graphene for improved dispersion state. Such highly dispersed TiO2-RGO nanocomposites were used to modify epoxy resin. Surprisingly, significant enhancement of the mechanical performance of epoxy resin was observed when incorporating the titania-graphene nanocomposites, especially the improvements in tensile strength and elongation at break, with 75.54% and 176.61% increases at optimal usage compared to the pure epoxy, respectively. The approach presented herein is easy and economical for industry production, which can be potentially applied to the research of high mechanical property graphene/epoxy composite system.


2021 ◽  
Vol 24 (1) ◽  
pp. 63-72
Author(s):  
Rui Li ◽  
Guoxing Yang ◽  
Yudan Wang ◽  
Lijia Liu ◽  
Qiang Wang ◽  
...  
Keyword(s):  

2018 ◽  
Vol 33 ◽  
pp. 02075 ◽  
Author(s):  
Tatyana Matseevich

The theme of the research is important because it allows to use hybrid materials as finishing in the high-rise constructions. The aim of the study was the development of producing coloured hybrid materials based on liquid glass, a polyisocyanate, epoxy resin and 2.4-toluylenediisocyanate. The detailed study of the process of stress relaxation at different temperatures in the range of 20-100°C was provided. The study found that the obtained materials are subject to the simplified technology. The materials easy to turn different colors, and dyes (e.g. Sudan blue G) are the catalysts for the curing process of the polymeric precursors. The materials have improved mechanical relaxation properties, possess different color and presentable, can be easily combined with inorganic base (concrete, metal). The limit of compressive strength varies from 32 to 17.5 MPa at a temperature of 20 to 100°C. The values σ∞ are from 20.4 to 7.7 MPa within the temperature range from 20 to 100°C. The physical parameters of materials were evaluated basing on the data of stress relaxation: the initial stress σ0, which occurs at the end of the deformation to a predetermined value; quasi-equilibrium stress σ∞, which persists for a long time relaxation process. Obtained master curves provide prediction relaxation behavior for large durations of relaxation. The study obtained new results. So, the addition of epoxy resin in the composition of the precursor improves the properties of hybrid materials. By the method of IR spectroscopy identified chemical transformations in the course of obtaining the hybrid material. Evaluated mechanical performance of these materials is long-time. Applied modern physically-based memory functions, which perfectly describe the stress relaxation process.


Polymers ◽  
2022 ◽  
Vol 14 (2) ◽  
pp. 245
Author(s):  
Yong Sun ◽  
Yongli Peng ◽  
Yajiao Zhang

In this work, a flame retardant curing agent (DOPO-MAC) composed of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide DOPO and methyl acrylamide (MAC) was synthesized successfully, and the structure of the compound was characterized by FT-IR and 1H-NMR. The non-isothermal kinetics of the epoxy resin/DOPO-MAC system with 1% phosphorus was studied by non-isothermal DSC method. The activation energy of the reaction (Ea), about 46 kJ/mol, was calculated by Kissinger and Ozawa method, indicating that the curing reaction was easy to carry out. The flame retardancy of the epoxy resin system was analyzed by vertical combustion test (UL94) and limiting oxygen index (LOI) test. The results showed that epoxy resin (EP) with 1% phosphorus successfully passed a UL-94 V-0 rating, and the LOI value increased along with the increasing of phosphorus content. It confirmed that DOPO-MAC possessed excellent flame retardance and higher curing reactivity. Moreover, the thermal stability of EP materials was also investigated by TGA. With the DOPO-MAC added, the residual mass of EP materials increased remarkably although the initial decomposition temperature decreased slightly.


Polymers ◽  
2019 ◽  
Vol 11 (9) ◽  
pp. 1522
Author(s):  
Ming Zhang ◽  
Mingqing Chen ◽  
Zhongbin Ni

We synthesized PPG-terminated tetra-carbamates as a new toughening additive for epoxy thermosets through facile addition reaction of hexamethylene diisocyanate (HDI) with poly(tetra-methylene glycols) (PTMG) and poly(propylene glycols) (PPG). The effects of prepared tetra-carbamates on the rheological behavior of neat epoxy resin were studied along with the various cured properties of their modified epoxy systems. Four carbamate groups (–NHCOO–) endow the prepared additives not only with good intramolecular interactions, but also with optimal intermolecular interactions with epoxy polymers. This results in the suitable miscibility of the additives with the epoxy matrix for the formation of the typical biphasic structure of microparticles dispersed in the epoxy matrix via polymerization-induced microphase separation. The impact strength and critical stress concentration factor (KIC) of cured modified epoxy systems with the additives are significantly higher than those of unmodified epoxy systems, without sacrificing the processability (Tg) and flexural strength. The toughening mechanism is understood as a synergism combination among the phase separation mechanism, the in situ homogeneous toughening mechanism, and the particle cavitation mechanism.


2020 ◽  
Vol 29 (5) ◽  
pp. 433-443 ◽  
Author(s):  
Ajinkya Satdive ◽  
Siddhesh Mestry ◽  
Pavan Borse ◽  
Shashank Mhaske
Keyword(s):  

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