PSI - Issue 65

Polina Tyubaeva et al. / Procedia Structural Integrity 65 (2024) 290–294 Polina Tyubaeva, Ivetta Varyan, Anatoly Popov / Structural Integrity Procedia 00 (2024) 000–000

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Table 1. Key properties of model polymer matrix for regenerative medicine.

Characteristic

PE

PLA

PCL

PHB

Crystallinity degree (%) Temperature of melting ( 0 С) Glass transition temperature ( 0 С)

25-50

20-30

40-50

50-60

120 - 20

160

65

177

55 16

- 60

2

Tensile strength (MPa)

20

20 50

40 10

Tensile modulus of elasticity (MPa)

700

160

Mw (g/mole)

1,2

4,8

3,5

4,5

Table 2. Potential of bioresorption of model polymer matrix for regenerative medicine.

Characteristic

Time (days)

PE

PLA

PCL

PHB

Loss of mass in the soil (%)

10 60

0 0 0 0

0 0 0 2

0,5

42

2 5

100 100 100 4,36

180 300

16

Mw (g/mole)

Before exposure

6,02

1,64

1,23

After exposure

6,02

1,64

1,08 (12% less)

3,02 (30% less)

Loss of mass in the phosphate buffer (%)

10 60

0 0 0

0 1 2

6 5

10 16 20

180

10

Mw (g/mole)

Before exposure

6,02

1,64

1,23

4,36

After exposure

6,02

1,64

1,06 (14% less)

1,74 (60% less)

As can be seen from Table 2, the state of the amorphous phase plays a special role in the process and rate of destruction. PE was a model matrix and remained stable throughout the entire period of the study. The PLA demonstrated the high stability of the polymer matrix. It is well known that when composting (at temperatures above 60 °C), the PLA has a high rate of biodegradation, which we do not observe at either room or subfebrile temperatures. The data obtained correlate well with the results known from the literature by Kandhasamy et al. (2017). It is also clearly seen on the model matrixes that the degree of crystallinity did not play a significant role in the rate of degradation of the polymer matrix. The more highly crystalline PHB (50-60%) had a significantly higher degradation rate than PCL (40-50%). In general, the process of polymer destruction under the influence of the environmental conditions without the participation of high temperature (up to 38 ° C) can be represented in general terms as a set of the following stages: (1) interaction of the polymer with the environment, which leads to a change in the chemical structure of the polymer; (2) destruction of the main chain of the polymer, accompanied by a decrease in the molecular mass by Sikorska et al. (2021). However, the specification of the mechanism will largely depend on the characteristics of a particular polymer, taking into account its chemical structure, molecular weight, and surface structure. Thus, the destruction of the polymer matrix is the process of breaking the chemical bonds of the main chain of a macromolecule, which may differ in mechanism and in the type of energy causing destruction. The role of a complex of factors on the destruction process has been well studied. However, the analysis of these factors in combination with the assessment of the effect of modifying additives and wound healing activators is of interest. Degradation of polymers under the influence of a biological environment, manifested by a decrease in its mass and volume should be named as biodegradation by Altaee et al. (2016). In the case of a process in contact with tissues of a living organism it should be named bioresorption. It is important to note that in general, polymer biodegradation is a complex multi–stage process that takes place under the influence of many factors by Altaee et al. (2016), such as