Study of the Effect of Laproxides on the Physical Properties and Deformation Behaviour of Epoxy–Bisphenol a Polymers

Abstract

The physicochemical differences in the modifying action of mono-and dilaproxides on the process of the structure formation of cured epoxy oligomers were established. The physically well-founded standard temperatures of epoxy-laproxide composites of different composition were established by differentiation. The results of investigating the high elasticity, the inversion features, and the deformation and strength properties of these densely crosslinked polymers are given. It is shown that the use of difunctional laproxide L-702 as a modifier of resins is preferable to the use of monofunctional oligoether epoxide L-301.Oligoether epoxides are widely used to modify densely crosslinked polymers in order to produce materials with a specified combination of processing and service characteristics. These effective modifiers include the laproxides [1]. They make it possible actively to influence the topological organisation of three-dimensional networks and accordingly the thermodeformation, inversion, and deformation and strength properties of the epoxy polymers [2]. In connection with the noted trend of practical application not only of the high elasticity effect of densely crosslinked polymers and filled matrices but also of their inversion features [3,4], it is of scientific and practical interest to investigate the effect of mono-and difunctional laproxides on the formation of the physical structure and properties of the most popular industrial polyepoxides.The investigation was conducted on epoxy-bisphenol A resins ED-20 and ED-16 (GOST 10587-84), and also on reactive laproxide modifiers -monofunctional laproxide 301G (TU 2226-337-10488057-97) (abbreviated below to L-301):and difunctional laproxide 702 (TU 2226-335-10488057-07) (abbreviated below to L-702):where R -m = 9-11.T h e c u r i n g a g e n t e m p l o y e d w a s isomethyltetrahydrophthalic anhydride (iso-MTHPA, acid number 665.0 15.0), and the curing accelerator was 2,4,6-tris(dimethylaminomethyl)phenol (UP 606/2).The amount of curing agent (X cur ) was determined with account taken of the content of epoxy groups in the modifier according to the empirical equation: X cur = 1.5(2605/AN)EG, g/100 g where AN is the acid number of the curing agent, and EG is the content of epoxy groups (%).Composites based on resins ED-16 and ED-20 with a content of each of the laproxides of 1, 3, 5, and 7% and a stoichiometric amount of curing agent with accelerator were prepared.