Preparation and Energy Storage-transmission Performance of RF Cryogels and Composites

Author:Yao Zuo

Supervisor:yao zheng jun


Degree Year:2018





Resorcinol-Formaldehyde(RF)aerogels as materials containing nano-pores have excellent properties of low density and heat conductivity,high capacity of sound absorption and fire resistance.It can be applied across large areas,such as transportation,buildings,ships and aircraft.Compared with traditional phenolic foam materials,RF aerogels possess lower conductivity and higher capacity of sound absorption.However,poor mechanical property and the brittleness limit its clinical application.In order to solve those problem,nano partices(ZnO,imvite)and glass fiber materials(glass fiber cloth and mat)was employed to improve mechanical properties of RF aerogel.In this idea,excellent performances of RF aerogels were used in combination with high strength and high modulus of reinforced materials in order to obtain a lightweight,high strength,fireproof and high sound absorption composites.On this basis,first,the preparing method and characterization of all kinds of RF aerogels and their composites were researched in this paper,then,their mechanical performance and storage-transmission of various energy(heat,sound and electricity)especially the affected factors were studied.At last,theories and usage mechanisms of storage-transmission of various energy were studied,and quantum theory were put forward to explain the mechanisms.In order to obtain RF aerogels which were suitable to this topic,the paper researched the preparation process of single-component homogeneous RF aerogel:first,formaldehyde and resorcinol precursor were preparaed,among them,the solid content of formaldehyde and resorcinol was 20%,RF aerogel with excellent performance were obtained after solvent replacement,pickling-aging and freeze drying(Na2CO3 was used as catalyst,solvent tert-butyl alcohol as replacement solution,acetic acid as aging solvent).On the basis,by slight adjustment of the solvent replacement and pickling-aging process,a kind of multiple structure RF aerogel was prepared,finally,polyaniline(PANI)and aniline/phytic acid(AP)aerogel components were added into its preparation process respectively for obtaining the multi-component of PANI/RF and AP/RF aerogel.The composition,structure,porosity and mechanical properties of various RF aerogels were characterized after the preparation of various RF aerogel materials,respectively.First,the mechanical properties of single-component RF aerogel materials were improved by compound with nano-particle and glass fiber reinforced materials.The results showed that:compared with single-component RF aerogel,the density of RF aerogel composites have increased,and the porosity and surface area have decreased,while their mechanical performances have obviously increased.Among them,nano-particles and glass fibers will enhance various mechanical properties of the aerogel in a certain degree,by contrast,the reinforced function of glass fiber was more obvious,it can improve the performance more than one order of magnitude.In addition,nano-particles combing with glass fiber reinforced RF aerogel had the best mechanical properties,its compressive,bending,tensile strength and impact toughness were 4.21 MPa,10.51 MPa,9.64 MPa and 5.79 kJ/m2 which were much higher than those of single-component RF aerogel.This was mainly because that:For particles,they will prevent stress from sequentially spreading to some degree;For fibers,on the one hand they have enhanced the structural strength,on the other hand their 3D networks have buffered their stress.Subsequently,the energy storage-transmission properties of various RF aerogels and their composites were studied,simultaneously,their various influence factors were analyzed.The results were displayed as follows:For the other aerogels that the paper designed,the multiple structure RF aerogel owned excellent sound absorption and insulation effect(Its sound insulation effect is larger than that of homogeneous RF aerogel for about three times),while PANI/RF and AP/RF aerogels exhibited excellent electrical storage performance(their specific capacitance are 280F/g and 420F/g under the current density of 0.2 A/g,respectively),In addition,the preparation of the Mold-AP and Mold-AP/RF aerogels obtained excellent directional conductivity(which were higher than non directional structure more than 4 times);For composite aerogels,nano-particles have enhanced the heat resistance and combustion performance of RF aerogel,while glass fibers have improved its heat resistance,but made its combustion performance declines to B1,in addition,glass fiber cloth have enhanced its heat insulation through declined the heat transmission;Simultaneously,the influence factors of their various energy storage-transmission were intensively studied.,in general,there existed similarity among all the influence factors,including solid content,component composition,structure,types of reinforced material,etc.,beside,there existed other influence factors such as temperature,compatibility,resistivity and so on.Finally,the various energy storage-transmission theories of all kinds of RF aerogel materials are analyzed,and their equations for theory analysis were deduced,combing with the experimental results which were shown in the fifth chapter,their various energy storage-transmission mechanisms were illustrated with examples.In addition,Through analyzing of their own storage-transmission theories and mechanisms of three energy and introducing the physics quantum concept,the general mechanism are summarized from the perspective of microscopic particles,which will combine the physical principle and the practical application of the materials together closely,and deepen the connection between the all subjects.