Effect of polyethylene glycol mixtures as ointment base on the physicochemical properties of Lavsan atraumatic wound dressings
Objectives. Modern atraumatic wound dressings are based on polyethylene terephthalate, or Lavsan, which is shaped to form threads. The aim of the study was to determine the reasons for Lavsan woven nets' hardening and becoming more trauma-prone during storage, and to find ways of eliminating these effects.Methods. We used differential scanning calorimetry, performed on a NETZSCH DSC 204 F1 Phoenix device, in a dynamic mode with a temperature range from 20 to 300 °C in argon flow to determine phase states, glass transition temperatures, and melting temperatures of Lavsan fibers (including those treated with polyethylene glycol mixtures). We performed rheoviscometry studies on a Brookfield DV2TLV rotational viscometer, with a SC4-16 thermostatic control unit, at the following temperatures: 25, 36.6, 40, 45, 50, and 55 °C, with shear rates ranging from 120 to 200 s-1 to determine dynamic viscosity and investigate the mixing characteristics of polyethylene glycols with different molecular weights.Results. We have established that samples of Lavsan woven nets, stored long-term in laboratory conditions (up to 2, 3, and 16 years), are in the crystalline state with a high degree of crystallinity. Upon heating these nets to 300 °C, it is possible to reduce the degree of crystallinity by 19-32%, but it does not completely eliminate the effect. Polyethylene glycols and their mixtures which exhibit non-Newtonian flow behavior and are used as an ointment base, have a significant effect on Lavsan's crystallinity. We have determined that the optimal ratio of polyethylene glycols for the modification of Lavsan nets is PEG-400:PEG-1500 = 80:20 wt %. Upon storing Lavsan woven nets in this mixture at room temperature, the Lavsan's crystallinity is greatly reduced, and upon heating the system, the crystallinity practically disappears.Conclusions. The effect of polyethylene glycol mixtures (the base for therapeutic ointments) with various molecular weights on the phase organization of Lavsan has been evaluated. As a result of this study, we can offer a new approach to reduce the injuring effect of synthetic (Lavsan) bases of atraumatic wound dressings.