Maria Rutkowska

Degradation of polyurethanes in sea water

Abstract The estimation of degradability of different polyurethanes in the Baltic Sea water and liquid medium containing sea water with sodium azide (NaN3) was the subject of this study. The incubation of polymer samples took place in both environments for a period up to 12 months. The characteristic parameters of sea water are presented and their influence on degradation of polyurethanes is discussed. The changes of weight, tensile strength and morphology of polyurethane samples were tested after particular period of incubation in both environments. It is demonstrated that the degree of degradation of polyurethanes in sea water is dependent on the degree of crosslinking.

Biodegradation of polycaprolactone in sea water

The biodegradation of polycaprolactone incubated in sea water for several weeks was investigated. For comparison, the hydrolytic degradation in a buffered salt solution was also examined. The weight, tensile strength and morphological changes were recorded during the period of biodegradation.

Chemical and Enzymatic Hydrolysis of Polyurethane/Polylactide Blends

Polyether-esterurethanes containing synthetic poly[(R,S)-3-hydroxybutyrate] (R,S-PHB) and polyoxytetramethylenediol in soft segments and polyesterurethanes with poly(e-caprolactone) and poly[(R,S)-3-hydroxybutyrate] were blended with poly([D,L]-lactide) (PLA). The products were tested in terms of their oil and water absorption. Oil sorption tests of polyether-esterurethane revealed their higher response in comparison to polyesterurethanes. Blending of polyether-esterurethanes with PLA caused the increase of oil sorption. The highest water sorption was observed for blends of polyether-esterurethane, obtained with 10% of R,S-PHB in soft segments. The samples mass of polyurethanes and their blends were almost not changed after incubation in phosphate buffer and trypsin and lipase solutions. Nevertheless the molecular weight of polymers was significantly reduced after degradation. It was especially visible in case of incubation of samples in phosphate buffer what suggested the chemical hydrolysis of polymer chains. The changes of surface of polyurethanes and their blends, after incubation in both enzymatic solutions, indicated on enzymatic degradation, which had been started despite the lack of mass lost. Polyurethanes and their blends, contained more R,S-PHB in soft segments, were degraded faster.

Biodegradation of the Blends of Atactic Poly[(R,S)-3-hydroxybutanoic Acid] in Natural Environments

The paper presents a part of the results of the biodegradation of the blends of natural poly(3-hydroxybutyrate-co-3-hydroxyvalerate) and atactic poly[(R,S)-3-hydroxybutanoic] acid or natural poly [(R)-3-hydroxybutanoic acid] in natural environments such as a compost containing active sludge and under marine exposure conditions in sea water.

Degradability of cross-linked polyurethanes based on synthetic polyhydroxybutyrate and modified with polylactide

AbstractIn many areas of application of conventional non-degradable cross-linked polyurethanes (PUR), there is a need for their degradation under the influence of specific environmental factors. It is practiced by incorporation of sensitive to degradation compounds (usually of natural origin) into the polyurethane structure, or by mixing them with polyurethanes. Cross-linked polyurethanes (with 10 and 30%wt amount of synthetic poly([R,S]-3-hydroxybutyrate) (R,S-PHB) in soft segments) and their physical blends with poly([d,l]-lactide) (PDLLA) were investigated and then degraded under hydrolytic (phosphate buffer solution) and oxidative (CoCl2/H2O2) conditions. The rate of degradation was monitored by changes of samples mass, morphology of surface and their thermal properties. Despite the small weight losses of samples, the changes of thermal properties of polymers and topography of their surface indicated that they were susceptible to gradual degradation under oxidative and hydrolytic conditions. Blends of PDLLA and polyurethane with 30 wt% of R,S-PHB in soft segments and PUR/PDLLA blends absorbed more water and degraded faster than polyurethane with low amount of R,S-PHB.

Degradability of organic-inorganic cellulose acetate butyrate hybrids in sea water

Degradability of organic-inorganic cellulose acetate butyrate hybrids in sea water Environmental degradability of novel organic-inorganic cellulose acetate butyrate hybrids obtained via solgel process was investigated. The degradation of hybrids was studied under marine exposure conditions in the Baltic Sea for a period of 25 weeks. The influence of characteristic parameters of sea water on the degree of degradation monitored by changes of weight and optical microscopy was discussed. The degraded samples were also examined by FT-IR spectroscopy. It has been established that the CAB/silica hybrids are more susceptible to biodegradation in sea water environment than pure cellulose acetate butyrate.

The morphology of polyurethane grafts and blends

Abstract The object of this study was the exploration of the morphology of partly sulfonated polystyrenes containing polyurethane grafts and blends of similar composition by dynamic mechanical studies (DMTA) and electron microscopy (TEM). The synthesis of grafts was accomplished by stepwise grafting onto the partly sulfonated polystyrene of N-methyldiethanoloamine by way of ionic interactions resulting from proton transfer followed by chain growth on the hydroxyl sites of the polyurethane structures. In the dynamic mechanical study two glasstransition temperatures are observed for blends and for grafts with long soft segments of polyurethane, but in the TEM study even grafts with only hard segments of polyurethane are heterogeneous. Transmission electron microscopy is a more sensitive method for investigation of the morphology of polymer alloys.

Effect of space network structure on molecular mobility of urethane elastomers

SummaryIn this study the changes in the width of the derivative NMR absorption line and the second moment as the function of temperature were investigated for typical urethane elastomers. The polymers crosslinked only by allophanate and biuret bonds as well as modified by the presence of carbon-carbon and ionic bonds were used. It has been found that carbon-carbon and ionic crosslinking bonds cause considerable changes in the glass transition temperature.

The influence of chemical structure on thermal properties and surface morphology of polyurethane materials

The surface morphology and thermal properties of polyurethanes can be correlated to their chemical composition. The hydrophilicity, surface morphology, and thermal properties of polyurethanes (differed in soft segments and in linear/cross-linked structure) were investigated. The influence of poly([R,S]-3-hydroxybutyrate) presence in soft segments and blending of polyurethane with polylactide on surface topography were also estimated. The linear polyurethanes (partially crystalline) had the granular surface, whereas the surface of cross-linked polyurethanes (almost amorphous) was smooth. Round aggregates of polylactide un-uniformly distributed in matrix of polyurethane were clearly visible. It was concluded that some modification of soft segment (by mixing of poly([R,S]-3-hydroxybutyrate) with different polydiols and polytriol) and blending of polyurethanes with small amount of polylactide influence on crystallinity and surface topography of obtained polyurethanes.

Branched Polyurethanes Based on Synthetic Polyhydroxybutyrate with Tunable Structure and Properties

Branched, aliphatic polyurethanes (PURs) were synthesized and compared to linear analogues. The influence of polycaprolactonetriol and synthetic poly([R,S]-3-hydroxybutyrate) (R,S-PHB) in soft segments on structure, thermal and sorptive properties of PURs was determined. Using FTIR and Raman spectroscopies it was found that increasing the R,S-PHB amount in the structure of branched PURs reduced a tendency of urethane groups to hydrogen bonding. Melting enthalpies (on DSC thermograms) of both soft and hard segments of linear PURs were higher than branched PURs, suggesting that linear PURs were more crystalline. Oil sorption by samples of linear and branched PURs, containing only polycaprolactone chains in soft segments, was higher than in the case of samples with R,S-PHB in their structure. Branched PUR without R,S-PHB absorbed the highest amount of oil. Introducing R,S-PHB into the PUR structure increased water sorption. Thus, by operating the number of branching and the amount of poly([R,S]-3-hydroxybutyrate) in soft segments thermal and sorptive properties of aliphatic PURs could be controlled.