PSI - Issue 5

L. ALEXANDRESCU et al. / Procedia Structural Integrity 5 (2017) 667–674 Laurentia Alexandrescu/ Structural Integrity Procedia 00 (2017) 000 – 000

5

671

RESULTS AND DISCUSSION Physical-mechanical tests were carried out in the Investigation laboratory from INCDTP - Division ICPI, accredited by RENAR, and materialized in the determination of hardness, elasticity, tensile and tear strength, attrition, residual elongation and elongation at break for thermo-oxidative aging (168h x 100°C) and normal state, and melt flow index. The hardness , for normal state, is 93°Sh A and increase to 95°Sh with the addition of ZnO and TiO2 nanoparticles. Thermo-oxidative aging increase the hardness value to 98°Sh A, which demonstrates that the curing process continues during processing. The sulfur and accelerating agents crosslinking system creates more stable cross bridges between the polymer chains, which are harder to break under temperature action. The tensile strength falls in the range from 10,2- 15.6 N/mm 2 , for normal state and 15.6 - 19.6 N/mm 2 after aging. The high values of this parameter are to be noted, values that are not found in classic rubber blends with the same hardness. Nanostructuring of EPDM rubber in the polyolefin matrix and PE-g-MA compatibilization requires elasticity with increased values at high hardness (22-32%), performance characteristic of these materials (Tables 2 and 3), maintaining its high values even after accelerated aging; Tear strength is an index with performance values, maintaining the same values (106-118 N/mm) due to tested elastic-plastic nanocomposites morphology (Tables 2, 3). After accelerated aging, the tear resistance values increase to 122.5%, a significant increase compared to classical blends In order to establish the technological parameters for processing Polymer nanocomposites PE/PE-g MA/EPDM/ nanoZnO and TiO2 dynamically crosslinked in finished products, tests were carried out to determine the melt flow index at a temperatures of 180°C and a pressure of 5 kg. The analysis of the obtained values (Table 2) show an increased flow compared to control sample N10 (1,75 g/10min) for the samples N11-N18. The flow index values are small due to the EPDM composition (1.75 at the sample without compatibilizer and maximum, 1.42 - the sample with the two reinforcement agents). Values grow poorly when adding ZnO and TiO2 nanosciences compared to the compatibilizing agent.

Table 2. Physical-mechanical characterization, normal state Symbols N 10 N 11 N 12

N 13

N 14

N 15

N 16

N 17

N 18

Physical-mechanical characterization - normal state

Hardness 0 Sh A SR ISO 7619-1:2011

93

94

93

93

94

94

94

94

95

Elasticity % ISO 4662:2009

22

22

22

24

26

26

28

32

24

Tensile strength, N /mm 2 SR ISO 37:2012 Elongation at break, % SR ISO 37:2012 Residual elongation, % SR ISO 37:2012 Tear strength, N/mm SR EN 12771:2003

10.2

11.1

11.2

12.1

10.5

12

13

14.2

15.6

640

720

820

827

660

660

700

700

667

367

447

587

607

447

420

500

447

427

114

108.5

106.5

113

113

118

110.5

107.5

112.5

Density, g/cm 3 , SR ISO 2781:2010 Attrition, mm 3 , SR ISO 4649/2010

0.96

0.96

0.96

0.9 6 32

0.96

0.96

0.96

0.96

0.98

39

29

33

29

29

25

25

25

Melt flow index, 180°C pressure of 5 Kg, g/10min

1.75

0.553

1.11

1.58

1.38

0.971

1.22

1.33

1.42