Preparation And Combustion Properties Of Intumescent Flame Retardant Epoxy Composites

A series of intumescent flame retardant epoxy composites has been prepared in this essay toexplore the effect of typical curing agent, toughener and flame retardant on their combustionproperties. The detailed outline is elaborated as follows:1. Single-molecule intumescent flame retardant (SMIFR) combined acid source, carbon sourceand gas agent into one set has been synthesized based on phosphorus acid, melamine, andpentaerythritol, then a series of intumescent flame-retardant epoxy composites has been preparedusing E-44epoxy resin, T31curing agent and SMIFR. The effect of T31content on combustionbehaviors and thermal degradation behaviors of the flame-retardant epoxy composites has beeninvestigated by cone calorimeter test (CCT) and thermal-gravimetric analysis (TG). The CCTresults indicate that the heat release rate (HRR) and smoke production rate (SPR) of the epoxycomposites reduce with the decrease of T31content. And EP-14with7.0wt%T31shows the bestflame retardancy among all samples. Furthermore, the TG results indicate that the EP-12whoseT31content is14wt%has the highest char forming ability and the best heat stability among all theepoxy composites.2. Several phosphate esters, used as curing agents for epoxy resins, have been synthesized.And, the structures of phosphate esters were characterized by nuclear magnetic resonance (NMR).Then a group of flame retardant epoxy composites has been prepared by curing epoxy resin withthese phosphate esters as curing agents. The flame retardancy and thermal degradation behaviors ofthe epoxy composites has been investigated by CCT and TG, respectively. The results of CCT indicate that phosphate esters can significantly decrease the heat release rate (HRR), total heatreleast (THR) and smoke production rate (SPR). EP-21, cured by butyl phosphate ester, shows thelowest HRR and SPR, and the best flame retardancy. The TG results indicate that phosphate esterscan enhance the char forming ability of composites. Among all the composites, EP-22cured byethyl phosphate ester shows the best char forming ability.3. A group of flame retardant epoxy composites were prepared based on E-44epoxy resin, T31curing agent, SMIFR, and CYH-277toughener, respectively. The influence of toughener content onproperties of the epoxy composites has been evaluated by CCT, TG, scanning electron microscopy(SEM), and smoke density test (SDT), respectively. The CCT results show that the addition ofCYH-277can decrease HRR, THR, SPR and delay the ignition time of flame retardant epoxycomposites, which indicates that CYH-277can enhance the flame retardancy of epoxy composites.And, EP-33with14wt%CYH-277toughener shows the best flame retardancy among all samples.The TG results show that CYH-277has an influence on the initial decomposition temperaturerather than on the char residues. And, the SDT results show that CYH-277couldn’t suppress smoke.4. A novel organic-inorganic intumescent flame retardant (EGM) has been synthesized bymodifying expandable graphite with pentaerythritol and phosphorus oxychloride. And, the structureof EGM has been charactered by infrared spectroscopy. Then, EGM was used as flame retardant forepoxy resin. And, combustion behaviors and thermal degradation properties of epoxy compositeshave been investigated by CCT and TG. And, the pyrolysis kinetics of the composites has beeninvestigated using Kissinger and Flynn-Wall-Ozawa methods. CCT data indicate that the additionof EG or EGM can greatly reduce the HRR and SPR of flame retardant composites. In the case ofcomposites with EGM, the THR decrease with the content of EGM increase. Furthermore, a morecompact char residue formed on the surface of the sample with EGM than that of the sample withEG during the combustion. The TG data show that EGM can enhance the char forming ability ofepoxy composites. And, the result of pyrolysis kinetic analysis show that the composites with EGMshow higher activation energy.