Influence of aliphatic epoxy monomer on the blowing-out effect in the flame retardant epoxy resins

An aliphatic epoxy monomer"polypropyleneglycol-diglycidylether(PPGDGE,YF878)"is loaded in the epoxy resins(EP)to evaluate the influence of epoxy structure on the blowing-out effect,which is caused by 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide(DOPO)and octaphenyl silsesquioxane(OPS).The flame retarding properties of these EP composites were tested using the LOI and UL-94 procedures.The pyrolytic gases produced and the thermal stability of the EP composites with different flame retardants were detected by TGA-FTIR in air.The negative effect of YF878 was detected from the TTI,HRR,and p-HRR results after the cone calorimeter test.The char produced by the EP composites after the cone calorimeter test was investigated by FTIR.It is proposed that the aliphatic chain of the YF878 is easy to break down and produce combustible gases,so it does not easily form a crosslinked structure in the condensed phase.These results are very helpful for investigation of the conditions under which the blowing-out effect in epoxy resins can be caused by synergy of phosphorous and silicon.

(EDTA)^(4-) supplements as superior modifier of the in-vitro-degradation properties of the magnesium alloy coated through discharge-assisted process

The(EDTA)^(4-)organic substituents were supplemented with alkaline silicates electrolyte,however in varying concentration to explore the microstructure,chemical composition and subsequent effects on the biodegradation of the PEO coated Mg AZ91 alloy.From surface analysis-,carried out through SEM,samples with zero-(EDTA)^(4-)were found-,lacking pancake structural features;however,supplementing electrolyte with(EDTA)^(4-),bulky and layered pancakes were obtained with minimum cracks and minimum porosity for EDT-1.From the phase and inner layer analysis,it was found that EDTA can significantly alter the surface layers composition and could act as a passivation agent-;however,individual polycrystalline phases were not found to form.The hardness value obtained for EDT-1 was~909.69 HV,the highest value found here which occurs with the shallowest indents found in this study.In-vitro degradation analysis was carried out using potentiodynamic polarization at room temperature,cyclic polarization at RT and high fever conditions(HFT~40°C).The corrosion potential for coated AZ91 was obtained as a positive value of~0.1 V,for the first time in the PEO research;however,the results were not supported by the cyclic polarization tests at room temperature and at HFT.The post corrosion microstructural analysis confirmed the effective role of EDTA up to 1.0 g·L^(-1)and revealed the formation of thin films during the forward polarization at HFT.

Effect of Lithium Nitrate on the Structure and Property of α-Al2O3 Platelets Prepared via Solid-state Reaction

The α-Al_2O_3 platelets were prepared via solid-state reactions and the effect of the amount of lithium nitrate additive on the property of the platelets was investigated. The ICP results indicated that the high temperature calcination process resulted in a large loss of lithium species because of volatilization, but there was still a small amount of residual lithium species in the α-Al_2O_3 platelets. The SEM micrographs showed that lithium nitrate led to decrease in the thickness of α-Al_2O_3 platelets and irregular morphology of aggregates. Pore structures results exhibited that addition of lithium nitrate led to decrease in the pore size and increase in the specific surface area of aggregates of α-Al_2O_3 platelets. The XRD and IR patterns suggested that the residual lithium and aluminum oxide formed LiAl_5O_8. The existence of LiAl_5O_8 was the basic reason for the changed performance of α-Al_2O_3 platelets.

An Overview of the Flame Retardants for Poly(vinyl chloride):Recent States and Perspective

As a versatile star product,poly(viny chloride)(PVC)has kept active in our dily lif all through since it was invented.However,the severe fire hazard andheavy smoke produced during combustion,particularly the extensively used flexible PC product,have been putzig manufacturers and researchers forages.Over the last decade,multifarious ftame retardants and smoke suppressants were developed for PVC materias.n this review combined literaturewith the results based on the research from our group,recent emerged fame retardants and smoke suppressants for PVC are introduced.Meanwhile,theflame retardant mechanisms and experimental analysis resuts are described to understand the relationship between characters of fame retardants (in-cluding chemical compositions,structures or morphologies)and fire performance of the composites.The potential substitutes for traditional harmfulflame retardant antimony trioxide are discussed aiming to the emphasis on increasing prominent environmental concerns.ln partcular,one section isdedicated to new approaches for the preparation of novel environmentally friendly and high-effciency fame retardants.is hoped that ths review wilnot only summarine the new emerged fame retardants and smoke suppressants for PVC,but also provide the new trend to prompt sequent explorationin both academic research and industrial application.