The Investigation About Interactions Between Water And Epoxy Resin Network In Near-critical Water

Degradation of epoxy resin polymer wastes in near-critical water(NCW) had triggered out the thinking to investigate the interaction between near-critical water and epoxy resin polymer network.There are many deep and broad investigations about the interaction between water and epoxy resin network, the existence of state of water in epoxy resin and water diffusion in epoxy resin after the literature review. However, the interaction between the near-critical water and epoxy resin has not yet appeared.For a better understanding of the nature of the near-critical water,diffusion behavior of near-critical water in the epoxy resin network, the relationship between the water absorption and the epoxy network structure,structure and properties of the epoxy network systems after the absorption of near-critical water,we choosed epoxy resin of the diglycidyl ether of bisphenol A (E-51) as the basic epoxy resin to be cured with three different curing agents to make three different kinds of epoxy network structure.To investigate the interaction between the NCW and epoxy resin polymer network through changing the reation time,temperature and reation ratio.The curing agents selected in this paper were:triethylenetetramine (TETA), methyl tetrahydro phthalic anhydride (MeTHPA) and4,4’-methylenedianiline (DDM).The relationships between water absorption of three different epoxy networks and the reation time,temperature and reation ratio were analyzed by weighing method.The result showed that the water absorption curve was similar to the pressure curve which was divided into three different stages of rate.Changing the reation ratio had little influence on the water absorption of all the systems. The order of the water absorption of all the systems under the same reation condition were the same which was:E-51/TETA> E-51/DDM> E-51/MeTHPA.It was inferred that the main factor affecting the water absorption was the concentration of polar groups rather than the free volume.Dynamic mechanical thermal analysis was used to obtain the tanδ and E’curves versus temperature and also the information about the Tg and crosslink density of the absorbent samples.The peaks of the tanδ curves became wider and smaller and even divided into two peaks indicating that the damage of the systems’ regularity and the diversification of motor units;The magnitude and trends of the reduction of storge modulus of different systems under the same experimental conditions were not quite the same.The relationships between the Tg of the sample and the water absorption and reaction conditions were also analyzed.The crosslink densities of samples before or after water absorption were calculated by rough rubbery theory combined with the data of storage modulus.Then the impact of the reation conditions on the crosslink densities and its relationship with Tg were discussed. At the end of this paper,the bending mechanical properties of the absorbent samples under different experimental conditions were tested.