Preparation And Properties Of Epoxy-based Lightweight Buoyant Material

The value of the oceans is so immense that 21st century is even called the century of the oceans. In China, with the acceleration of ocean development and the implementation of ocean exploitation strategy, the application prospects of light-weight, high intensity buoyancy materials are becoming much brighter. In the field of deep-sea buoyancy materials research and technology development, some of the buoyancy materials used on deep-sea equipment has been preliminarily developed. At present, the domestic need of the high-performance marine buoyancy materials mainly depends on importing and the related domestic research on the materials is still at its initial stage. The future successfully domestic developed light-weight, high intensity and high-performance solid buoyant materials might to a large extent replace imported materials which will break the current market monopoly of the material. In the light of the current situation, it is of notable significance to do the research on the high-performance solid buoyant materials.With the comprehensive consideration of the preparation, environmental characteristics and other factors, a low-temperature fast curing system was identified in this paper which was based on the bisphenol A epoxy resin (E-44)/neopentylglycolther (XY678)/triethylenetetramine(TETA) polymer. And based on the calculated curing kinetics equation, the characteristics of the curing reaction system was predicted. The curing process of the system was also identified as room temperature curing gel/2d+after curing 80℃/1h. The curing system has the following strengths: the curing process is uncomplicated and the energy consumption is low. The data were measured by non-isothermal DSC which were calculated by extrapolation method showing the initial temperature of the curing system is 32.55 ℃, the peak temperature is 79.55 ℃ and the final temperature is 136.6 ℃. The E-44/X Y678/TETA curing kinetics system was also studied by DSC method and the result of the study showed its apparent activation energy Eo was 46.74kJ/mol, its pre-exponential factor A was 6.664×105S-1, its reaction series n was 0.88 and the curing was first order reaction.The relationship between the density and void fraction of the buoyant materials which were based on the different volume fraction microspheres bytheoretical calculations and actual test data.The results showed that with the increase of the volume fraction of the microspheres, the materials density is significantly reduced; while the actual tested materials density was slightly lower than the theoretical calculated one demonstrating that there were certain amount of air bubbles the materials also contained a small amount of between the surface of the microspheres and the matrix. In the follow-up experiments, after the mass fraction of plastic microspheres and glass fiber was determined by this calculation method, a light buoyant materials was prepared of which the density was 0.706g/cm3, the compression strength was 67.49MPa and the saturated water absorption was less than 1%. After modifying the glass microsphere surface with silane coupling agent, the modification effects on the comprehensive performance of the composite materials was studied; the failure mechanism of the buoyancy materials analyzation exposed the damage was mainly caused by two factors which were interfacial debonding between the microspheres and resin matrix and glass microsphere destruction. Effective ways to improve the overall performance of the buoyancy were proposed which were applying the resin matrix with powerful mechanical properties, applying the hollow microspheres with high compressive strength and strengthening the interfacial bond between the resin and microspheres.The effects of glass microspheres surface being modified by Graphene oxide (GO) and the adulteration of low density plastic microspheres on the comprehensive performance of the composite materials were studied. The tests were divided into three phases which are the glass microspheres (phr= 20) absorbing GO before its restoration; the glass microspheres absorbing GO after its restoration and the hollow glass microspheres absorbing GO only. The test results indicated that the buoyancy materials obtained the highest compressive strength when prepared in the third phase which was the hollow glass microspheres absorbing GO only phase. Comparing the materials prepared without Go absorption, the test data also showed that when the density of GO was 0.7 mg/mL, the compressive strength of the composite materials was 92.75 MPa which improved by 8.20%while its density was 0.883g/cm3 which only improved by 1.12%. The study indicated that by plastic microspheres and glass microspheres being mixed as a filler added to the resin matrix, the prepared materials could meet the high compressive strength and low density requirements which enriched the preparation process. The results showed that by adjusting the mass fraction of the glass microspheres and plastic microspheres, the buoyant materials with the density of 0.454-0.872g/cm3 and the compressive strength of 85.72-35.21MPa could be prepared.The reinforcement mechanism of chopped glass fiber to glass microspheres/epoxy matrix and the effect of surface treatment by the fiber impregnating on buoyancy materials properties were studied. The results indicated that the factors like the interfacial bonding strength between the glass fiber and the epoxy matrix, the mass fraction and dispersed state of the glass fiber were all vital factors affecting the performance of the buoyancy materials. As reinforcement phase (dispersed phase), after being added to the resin matrix, the glass fiber became the main carrier of external forces as its the modulus and strength were much higher than the matrix materials. Through the fiber impregnating surface treatment, the interface bonding strength between the fibers and the resin matrix got improved. Under the condition of the mass fraction of glass microspheres was 40, glass fiber length was lmm and the mass fraction of the glass fiber was 1, the density of the prepared lightweight buoyant materials was 0.724g/cm3,its compressive strength was 78.21 MPa and its compressive strength ratio was 108.03MPa/(g/cm3). The glass fiber/epoxy matrix composite materials was formed by the cured epoxy resin matrix which was interspersed with two kinds of very tiny fine shaped reinforcing materials (the diameter was in microns). In this materials, the glass fiber and glass microspheres bore the majority of the load while the resin matrix acted as the bonding, supporting and enhancing protection roles which could also transfer stresses. When the materials received external stress, the stress was first transferred to the fiber-reinforced frame (elastic deformation zone); with the increase of the external stress, the bonding interface between the glass fiber and the resin matrix was damaged and the fiber-reinforced frame appeared fracture. The overwhelming stress led directly to the damage of the bonding interface between the glass microspheres and the resin matrix and the smash of the glass microspheres (plastic deformation zone), and consequently, to the damage of the whole materials.