Functionalization Of Nano Atttapulgite And Its Application And Properties In Polyimide

Palygorskite is an important scarce non-metallic mineral resource.It is known as"industrial monosodium glutamate"and"the land of thousands of uses and the king of thousands of lands".At present,the research on the functionalization of attapulgite in heat treatment is mainly focused on the heat treatment temperature below 800?,and the experimental research is carried out before the structure of attapulgite collapses.However,there are few studies on the changes of crystalline phase and physical and chemical properties of attapulgite after calcined after 800?.It is a new research topic that nano attapulgite is gelated into geopolymer and then sintered into new ceramic products.Second,attapulgite organic functional help improve particles dispersed in the polymer properties and bonding properties,organic modification of attapulgite materials to enhance reinforcing effects of polymer materials,organic functionalization of attapulgite and polyimide ATP/PI composite membrane preparation,exploring the ATP/PI composite membrane performance change also has great significance.It can improve some properties of PI film and improve the high value application of attapulgite.The research contents of this thesis are as follows:(1)Resear chonstructural evolution and property changes of heat-treated attapulgite Calcination heat treatment of attapulgite at 16 temperature points:100?,200?,300?,400?,500?,600?,700?,800?,900?,950?,1000?,1050?,1100?,1050?,1200?,1250?.The evolution law of attapulgite crystal structure,heat resistance,adsorption abilityofformaldehyde and toluene and hardness change law were investigated.The nanoattapulgite fibers begin to melt at 900?,and from 900?to 1150?is the phase transition from Mg₃Al₂(Si O₄)₃)to quartz,engentry(Mg₂[Si₂O₆]Fe₂[Si₂O₆])and kyanite(Al₂[Si O₄]O).The quartz phase changes into a new phase at 1050?.When the heat treatment temperature is 1200?,the quartz phase decreases and the new phase Ca₂Al₄Si₈O₂₄is formed.A new phase calcium sulfate(Ca SO₄)was formed at 1250?.Attapulgite treated at 1100?and 1200?has almost the same weight loss rate at 1000?as attapulgite treated at 800?,with stable thermal properties.ATP-200?is the highest adsorption rate of toluene and formaldehyde,which are 28.7%and 26.6%,respectively.It can become a cheap adsorbent to replace activated carbon.ATP-1150?reached the highest hardness of 8.3,mainly due to the formation of crystalline phase of kyanite(Al₂[Si O₄]O).(2)In view of the research on the structure and properties of nano-attapulgite gelation sintering molding,nano-attapulgite was used as raw material to prepare the geopolymer of nano-attapulgite by sol-gel method,film covering curing and thermal curing,and then it was sintered at 1100?,1150?,1200?and 1250?.The morphology,heat resistance,heat absorption and heat release,density and hardness of nanoattapulgite geopolymer were compared before and after sintering.The higher the sintering temperature,the higher the sample heat absorption,the heat absorption ATP-4>ATP-3>ATP-2>ATP-1.1100?sintered samples lost 2.09%of their weight when nitrogen was heated to 1000?;1150?sintered samples lost only 0.14%of their weight when nitrogen was heated to 1000?;1200?and 1250?sintered samples lost almost no weight when nitrogen was heated to1000?.The density of samples in descending order is ATP-2>ATP-1>ATP-3>ATP-4>ATP-0.The hardness of samples is in the order of ATP-2>ATP-3>ATP-2>ATP-4>ATP-0.The hardness increases after sintering,up to 8.5.The new nano attapulgite ceramics prepared are expected to become a new type of ceramics that can be industrialized and improve the high value application of attapulgite.(3)Preparation and properties of modified attapulgite based polyimide films.Modified attapulgite(ATP)was prepared by organic functionalized attapulgite nanoparticles with KH-550 silane coupling agent.A series of homopolymer polyimide composite films with different ATP content were prepared by in-situ polymerization using PMDA as dianhydride monomer,ODA as diamine monomer and ATP as filler.It was found that the tensile strength of ATP nanoparticles reached 82.70Mpa when the doping amount was 20%,and the elastic modulus reached 3.46Gpa when the doping amount was 40%.When the doping amount is50%,the permeability and selectivity of PI film reach an optimal balance point,which ensures the passage of gas separation effect and greatly improves the permeability of various gases.ATP can be effectively compounded with polyimide to improve the gas permeability efficiency and the low price,which can also improve the high-temperature dimensional stability and mechanical properties of PI film.ATP/PI composite film is a promising new separation film for gas separation,which has great application scenarios.