PSI - Issue 37

S. Valvez et al. / Procedia Structural Integrity 37 (2022) 738–745

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S. Valvez et al. / Structural Integrity Procedia 00 (2019) 000 – 000

treatment must be carried out for a maximum temperature of 90 ºC and a maximum exposure time of 240 min. On the other hand, for 4D applications these parameters must be considered and with values higher than those mentioned above. However, these values must be selected depending on the desired application. In terms of hardness, Table 5 shows the values obtained for the different materials and test conditions studied.

Table 5. The effect of annealing treatment on the hardness.

PETG SD [MPa]

CFPETG

KFPETG

Samples Group

Average [MPa]

Variation [%]

Average [MPa]

SD [MPa]

Variation [%]

Average [MPa]

SD [MPa]

Variation [%]

Control

9.8

0.3 0.4 0.8 0.3 0.5 0.3 0.5 0.5 0.2 0.3

-

11.7 12.4 12.8 13.4 12.5 12.9 14.0 12.3 13.0 14.8

0.8 0.7 1.0 0.5 0.9 0.5 1.2 0.9 0.9 0.9

-

11.7 11.9 12.0 12.2 12.5 12.9 13.1 13.4 14.1 14.2

0.9 1.2 0.9 1.0 0.4 0.8 0.9 1.2 0.6 0.7

1 2 3 4 5 6 7 8 9

11.2 10.4 10.7 11.7 10.3 10.5 10.8 10. 8 11.0

13.4

5.6 9.2

1.3 2.3 3.8 6.4

5.3 8.4

14.3

19.2

7.1

4.8 7.2 9.9 9.3

10.1 19.6

10.5 11.7 14.8 20.2 21.6

4.9

11.2 26.1

11.9

It is possible to observe that, for composite materials, hardness increases with increasing temperature and exposure time. For example, considering the samples produced with CFPETG and an exposure time of 480 min, the hardness increases 14.5%, 19.7% and 26.5% for temperatures of 90 ºC, 110 ºC and 130 ºC and when compared with the control samples (without annealing treatment), respectively. For KFPETG, these values are 4.3%, 12% and 21.4%, respectively. However, keeping the temperature constant for values of 110 ºC, the hardness increased for the CFPETG material around 3.2% and 12% after 240 min and 480 min of exposure time and in relation to the value obtained with 30 min of exposure. In relation to the KFPETG material, these values are, respectively, 3.2% and 4.8% higher than the value obtained with 30 min of exposure. Finally, in terms of PETG, the hardness increases, but with less expressive values. Lastly, the values obtained in the bending tests are presented in Table 6 in terms of flexural strength and in Table 7 in terms of flexural modulus.

Table 6. The effect of the annealing treatment on the bending stress.

PETG SD [MPa]

CFPETG

KFPETG

Samples Group

Average [MPa]

Variation [%]

Average [MPa]

SD [MPa]

Variation [%]

Average [MPa]

SD [MPa]

Variation [%]

Control

66.9 72.6 70.7 68.9 73.4 71.3 68.5 73.7 71.9 68.0

1.4 0.8 0.9 1.2 1.0 1.2 3.1 3.5 1.0 1.8

-

79.2 78.3 79.8 81.9 76.7 76.5 86.0 83.7 97.2

1.0 1.0 3.3 1.8 1.3 3.0 2.6 2.3 3.3 3.3

-

47.7 48.6 50.1 51.0 49.6 52.2 52.5 50.5 52.8 53.0

1.0 1.5 1.7 1.8 1.0 1.3 3.2 2.2 1.6 1.5

-

1 2 3 4 5 6 7 8 9

8.4 5.6 2.9 9.7 6.6 2.4

-1.2

1.8 4.9 6.9 4.0 9.3

0.7 3.4

-3.2 -3.5

8.5 5.6

10.1 5. 9 10.7 11.1

10.2

7.5 1.6

22.7 31.8

104.4