PSI - Issue 82

Lenka Markovičová et al. / Procedia Structural Integrity 82 (2026) 274 – 280 L. Markovičová et al./ Structural Integrity Procedia 00 (2026) 000–000

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The test procedure was as follows: the sample was placed on the durometer base. Using a lever, the indenter was pressed vertically into the sample. Once the indenter penetrated the sample, the hardness value appeared on the durometer display. The test was performed on six samples. Three samples with different filler contents (10%, 20%, and 30%) were not exposed to UV radiation. The other three samples, also with different filler contents (10%, 20%, and 30%), were exposed to UV radiation. The Dynstat device is used to determine the toughness characteristics of test specimens (according to standard STN 64 0611). The calculation of the characteristics assessing the impact test is based on the measured energy A n consumed to fracture the test specimen. Rheological tests were performed on a Physica MCR301 oscillatory rheometer (Fig. 2) using a PP measuring system, according to ISO 6721.

Fig. 2. Rheometer Physica MCR301.

The instrument is equipped with a temperature control unit, allowing measurements up to +450 °C, or, when connected to a cooling unit with liquid nitrogen, down to −150 °C. Samples of the tested materials were subjected to frequency analysis (Frequency Sweep – FS) at a temperature of 320 °C (based on the characteristics of the evaluated material), with an angular measurement frequency range of 0.05–500 s⁻¹. Rheological measurements were conducted on both the base material and the material after exposure. Rheological measurements allow for the comparison of values of the complex dynamic viscosity η*, as well as the storage modulus G′ and the loss modulus G″. In addition, the position of the intersection point of the curves representing both moduli can be observed, indicating the transition from viscous and deformational behavior to more elastic behavior, serving as a qualitative characteristic of the material. If degradation occurs in polymers, it may also be reflected in this measured characteristic. A horizontal shift of the modulus intersection provides information about changes in the average molecular weight, while a vertical shift indicates changes in the molecular weight distribution. 3. Results and discussion Ten Shore D hardness measurements were performed on each sample. The arithmetic mean of all measurements is considered the final value. The results are presented in Table 1.

Table 1. Hardness Shore D. Filler content (%)

Shore D (0 UV)

Shore D (500 UV)

10 20 30

81 84 85

78 79 84