Physical and Mechanical Properties of a Photopolymer System before and after UV Curing. 2. A Theoretical Analysis

A theoretical analysis of the physical and mechanical properties of a photopolymer resin before and after photocuring under the action of UV irradiation is conducted considering experimental spectra of internal friction $$\lambda = f\left( T \right)$$ and temperature dependences of frequency $${{\nu }} = f\left( T \right)$$ of a freely decaying oscillatory process in a temperature range of from −150 to 250°C. Based on the phenomenological model of a standard linear body, a calculation of the physical and mechanical (temperature position of the maximum of the loss peak, its intensity and frequency of the oscillatory process in the loss maximum, shear modulus defect) and physicochemical (energy of activation, discrete relaxation time) characteristics for each of the dissipative processes found in the internal friction spectrum is conducted; the mechanisms of internal friction are determined, and a plausible structural interpretation of the appearance of each dissipative process that results in a drastic change in the ratio of the elastic and inelastic characteristics of the studied materials in the spectrum is proposed. Based on the obtained experimental and theoretical results, it turns out to be possible to find out the temperature ranges in which photopolymer materials possess stable physical and mechanical properties.