PSI - Issue 30

A.A. Kychkin et al. / Procedia Structural Integrity 30 (2020) 64–70 A.A.Kychkin et al / Structural Integrity Procedia 00 (2019) 00 – 00

68

5

Inflection point, ( ° С)

156.2

141.4

140.2

Extrapolated exit of the transition on the modulus of elasticity curve, ( ° С )

181.5

175.3

179.9

Peak on the mechanical loss tangent curve, ( ° С )

171.9

157.4

171.0

Peak on the modulus of loss curve, ( ° С )

138.9

139.3

137.5

Figure 4 presents temperature dependent elastic modulus, modulus of loss, and mechanical loss tangent of BFRP rebars 6, 8, and 10 mm in diameter after exposure in Gelendzhik. Table 2 provides the values of characteristic temperatures for BFRP rebars after exposure in Gelendzhik.

Fig. 4. Temperature dependent elastic modulus (E’), modulus of loss (E’’), and mechanical loss tangent (tgδ) of BFRP rebars a fter exposure in Gelendzhik, where Ø6mm is green, Ø8mm is red, and Ø10mm is blue.

Table 2 - Results of dynamic mechanical analysis for BFRP samples 6, 8, and 10 mm in diameter after exposure in Gelendzhik Factor Ø6 mm Ø 8mm Ø 10mm Extrapolated value for the start of the transition on the modulus of elasticity curve, ( ° С ) 127.6 121.6 121.4 Inflection point, ( ° С) 143.1 142.9 135.8 Extrapolated exit of the transition on the modulus of elasticity curve, ( ° С ) 183.0 165.0 158.1 Peak on the mechanical loss tangent curve, ( ° С ) 146.5 146.1 140.5 Peak on the modulus of loss curve, ( ° С ) 143.1 142.3 135.7

Glass transition temperature studies of rebar samples show that exposure on an open site in Gelendzhik resulted in structuralization of the polymer matrix accompanied by an 28% increase of dynamic elastic modulus and a slight