PSI - Issue 10

E. Tsetsekou et al. / Procedia Structural Integrity 10 (2018) 227–234

232

E. Tsetsekou et al. / Structural Integrity Procedia 00 (2018) 000 – 000

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Maximum Load at Break - Maple

10000 11000 12000 13000

0 1000 2000 3000 4000 5000 6000 7000 8000 9000

Controls UV RH-T

Load (N)

(a)

Casein Fish Glue Vinavil Rabbit Glue Paraloid B72

Maximum Load at Break - Fir

10000 11000 12000 13000

0 1000 2000 3000 4000 5000 6000 7000 8000 9000

Controls UV RH-T

Load (N)

(b)

Casein Fish Glue Vinavil Rabbit Glue Paraloid B72

Fig. 7. The maximum load at break point for the five adhesives applied on maple (a); and fir (b) samples before and after accelerating ageing with UV and RH-T cycles. All values are average of four replicates.

Reversibility results are presented in Table 1. For control samples, Paraloid B72, fish glue and Vinavil were the easiest to remove from wood surface followed by casein and lastly rabbit-skin glue. UV ageing does not appear to change the reversibility of Paraloid B72, fish glue, casein and rabbit-skin glue in either species of wood. However Vinavil became harder to remove after UV ageing and showed greater change in maple samples than in fir samples. Following RH-T cycles, all adhesives, in both types of wood, showed a small change in reversibility comparing to the control samples. The easiest to remove was again Paraloid B72, fish glue and Vinavil followed by casein and lastly rabbit-skin glue. All of the adhesives were found to be reversible and their removal from wood surface was completed without damaging the surface. Regarding colour stability, based on the results of ΔΕ * obtained (Fig.8), Vinavil and Paraloid B72 beside their anticipated deterioration (Vaidergorin et al (1987); Chiantore and Lazzari (2001)) were found to be the most stable adhesives under UV ageing. It has to be noted that the relatively low ΔΕ * values measured for the three natural ad hesives are not considered representative of the resistance of these adhesives to photo degradation. These glues when applied on wood, create semi-transparent or even opaque films and thus they probably cannot incorporate the ΔΕ * of wood colour alteration occurring during UV ageing (Fig.8). On the contrary, Paraloid B72 and Vinavil create clear, transparent films and thus their relatively high ΔΕ * values may result by the integration of the wood ΔΕ * induced by UV.