Synthesis, Characterization And Degradability Of PBS-based Biodegradable Materials

Development trends and applications of PBS-based biodegradable materials were described.Poly (butylene succinate) ,linear aliphatic polyesters—poly (butylenes adipate), poly (glycol adipate), poly (glycol succinate), poly (butylene succinate -co- ethylene glycol)s and PBS/PET blends with different compositions were synthesized. Structure of polymer morphology and degradation production was studied by Differential Scanning Calorimetry and IR spectra. From the above, mechanism of degradation of PBS-based linear aliphatic polymers and PBS/PET blends was discussed. This paper put forward a practical method for synthesizing high molecular weight PBS, for the first time studied mechanism and conditions of reaction processing of PBS/PET blends, analyzed composition and structure of degradation production, and provided references for the controlled degradation and future application of PBS-based linear aliphatic polymers. The main content of research was listed as follows:1. Effectors for method for synthesizing high molecular weight PBS were analyzed, and then the suitable condition was obtained. Structure of production was characterized. 2. Melting point, hydrophilic properties, degradability of PBS and other linear aliphatic polymers were analyzed. Hydrophilic properties were improved by introduction of PEG segments to PBS.3. The influence of composition, reaction time, reaction temperature of PBS/PET blends to molecular weight and melting index were investigated, and processing properties of production were discussed further.4. Thermal properties and structure were measured by Differential Scanning Calorimetry. IR spectra, from Tm , Tg , endothermic form, dissociation enthalpy, crystallinity andtypical absorbances were discussed.5. Degradability of PBS and PBS/PET blends with different pH water solutions was investigated, and the relationship between pH and rate of PBS degradation was analyzed, and effects of blends structure and morphology to rate of degradation were studied.6. Production of degradation of PBS/PET blends were studied, the influence of blend reaction to polymer degradability was discussed further. The results showed that:Suitable conditions for high molecular weight PBS included that at the first step, when the acid value reached the invariableness, the reaction time was 3 hours and temperature was 150℃;at the second step, reaction time is 2～3 hours, and temperature rose gradually from 220℃ to 260℃,and pressure force for reaction was 1000Pa, and mol ratio of succinate and butylene was 1:1.5. Melting point of PBS was 114℃ , the highest among the linear aliphatic polymers above, and PGA was 47.2℃, the lowest; melting point of poly (butylene succinate -co- ethylene glycol)s decreased with increase of the content of PEG.Linear aliphatic polyesters with the lower melting temperature was more susceptible to biodegradation than the linear aliphatic polyesters with the higher melting temperature. Hydrophilic properties of PBS were improved by the introduction of PEG segments.PBS/PET blends had shown two distinct Tm values and separated crystallization phase, and PBS and PET crystallized according to their own cell unit. A transesterification reaction between two polyesters at 290℃ and 30mins of blend. Increase of reaction temperature and reaction time was favorable for transesterification. Increase of the content of PET in PBS/PET blends was unfavorable for degradation. Rate of degradation of blends was susceptible to morphology, and degradation proceeded more preferentially in amorphous regions than in crystalline regions. When transesterification happened in PBS/PET blends, there were PET units in production of degradation of blends. Introduction of PBS segments imparted degradability to hard macromolecular PET.