Degradability of Polyurethanes and Their Blends with Polylactide, Chitosan and Starch

Abstract

One of the methods of making traditional polymers more environmentally friendly is to modify them with natural materials or their biodegradable, synthetic equivalents. It was assumed that blends with polylactide (PLA), polysaccharides: chitosan (Ch) and starch (St) of branched polyurethane (PUR) based on synthetic poly([R,S]-3-hydroxybutyrate) (R,S-PHB) would degrade faster in the processes of hydrolysis and oxidation than pure PUR. For the sake of simplicity in the publication, all three modifiers: commercial PLA, Ch created by chemical modification of chitin and St are called bioadditives. The samples were incubated in a hydrolytic and oxidizing environment for 36 weeks and 11 weeks, respectively. The degradation process was assessed by observation of the chemical structure as well as the change in the mass of the samples, their molecular weight, surface morphology and thermal properties. It was found that the PUR samples with the highest amount of R,S-PHB and the lowest amount of polycaprolactone triol (PCLtriol) were degraded the most. Moreover, blending with St had the greatest impact on the susceptibility to degradation of PUR. However, the rate of weight loss of the samples was low, and after 36 weeks of incubation in the hydrolytic solution, it did not exceed 7% by weight. The weight loss of Ch and PLA blends was even smaller. However, a significant reduction in molecular weight, changes in morphology and changes in thermal properties indicated that the degradation of the samples should occur quickly after this time. Therefore, when using these polyurethanes and their blends, it should be taken into account that they should decompose slowly in their initial life. In summary, this process can be modified by changing the amount of R,S-PHB, the degree of cross-linking, and the type and amount of second blend component added (bioadditives).

Surface Characterization and Anti-Biofilm Effectiveness of Hybrid Films of Polyurethane Functionalized with Saponite and Phloxine B

“…An example is the use of PU in the manufacture of implants, for which biodegradable polymers appear to be most promising. In the case of such implants, modification with antimicrobial agents may have an added value [7,8]. Other examples are fine fabrics based on PU composites that can serve as materials for antimicrobial membranes and filters and, in the medical industry, as wound dressings [9].…”

Susceptibility to Degradation in Soil of Branched Polyesterurethane Blends with Polylactide and Starch

“…The polycaprolactone segments are considered to be one of the slowest degrading polymers among all those that are biodegraded [ 23 ]. As shown in previous studies, blending of PCL with R,S-PHB in the soft segment increased the susceptibility of PURs to degradation under hydrolytic and oxidative conditions [ 17 ]. Moreover, increasing the amount of R,S-PHB in the PUR structure slightly accelerated the degradation process of the samples subjected to soil burial test ( Figure 1 A,B).…”

“…Despite only a small amount of them being present in the samples, both PUR 10/5 and PUR 20/5 blends degraded faster in the soil than pristine PURs. While PLA blends decreased their mass at a similar level as in the case of hydrolysis ( Figure 1 A,B), the degradation of PUR 20/5 + St in the soil was slower ( Figure 1 B) [ 17 ]. It is clearly visible how important in starch degradation is the presence of water, of which there is much less in the soil.…”

“…Moreover, R,S-PHB as a synthetic equivalent of the natural PHB has a chemical structure recognizable by microorganisms living in the soil. Thus, although the amount of water in the soil was significantly lower than in phosphate buffer, the reduction in mass of PUR 10/5 in the soil was slightly higher than when they were hydrolyzed [ 17 ]. The acceleration of the kinetics of polyesterurethane degradation under the influence of microorganisms compared to abiotic factors has already been observed many times [ 24 , 25 ].…”

“…Thus, the main reason for the research described in this publication is to investigate the susceptibility of branched PUR materials modified with polyesters, R,S-PHB and PLA, and starch for degradation in anthropological soil. This paper is a continuation of our previous research on determining the susceptibility of these materials to degradation in a hydrolytic and oxidizing environment [ 17 ]. Degradability was determined using attenuated total reflectance Fourier transform infrared spectroscopy (ATR FTIR), proton nuclear magnetic resonance spectroscopy ( 1 H NMR), gel permeation chromatography (GPC-MALLS), differential scanning calorimetry (DSC), scanning electron microscope (SEM), optical microscopy (OM) and a goniometer (static water contact system).…”