In this study the modification of a hyperbranched polyester polyol of second generation (HBP2G) with polylactic acid (PLA) was carried out. The proportions employed of PLA were: 10 (HBP2G90), 25 (HBP2G75), 40 (HBP2G60), and 55 wt % (HBP2G45). The materials obtained were characterized by acid value, hydroxyl value, infrared, nuclear magnetic resonance (NMR), chromatography exclusion size (SEC), dynamic light scattering, thermogravimetric, differential scanning calorimetry, and rheology analyses. The analyses of the acid values and hydroxyl values showed that the reaction between HBP2G and PLA occurred. The greater modification degree was 92.00%. The NMR spectrum shows that evidently the PLA was grafted onto the HBP2G. The SEC analysis revealed that all samples presented values of average molecular weight (M n ) and weight average molecular weight (M w ) higher than the HBP2G. The thermal stability of the materials increased with respect to HBP2G and it was independent of the modification degree.
A hyperbranched polyester polyol of the second generation (HBP2) was modified with polylactic acid (HBP2-g-PLA) and employed as a compatibilizer for plasticized tapioca starch (TPS)/polylactic acid (PLA) blends. The effect of the compatibilizer HBP2-g-PLA was evaluated in comparison to the control sample (TPS/PLA blend without HBP2-g-PLA). The torque value of the TPS/PLA blends with HBP2-g-PLA was lower than that of the control sample, while thermal stability and crystallinity followed opposite behavior. The glass transition temperature (T g) and degree of crystallinity of the TPS/PLA blends with HBP2-g-PLA decreased with increasing mass fraction of HBP2-g-PLA. By scanning electron microscopy (SEM), it was observed that the morphology of the TPS/PLA blends with HBP2-g-PLA was more homogeneous than that of the control sample, confirming that HBP2-g-PLA acted as a compatibilizer and plasticizing agent to the TPS/PLA blends. Rheological analysis of the compatibilized TPS/PLA blends indicated the presence of microstructure.
With the aim of to contribute to the employ of new compatibilizing agent and to the preparation of biodegradable materials, in this study were obtained thermoplastic starch/polylactic acid blends and was evaluated the compatibilizing effect of a hyperbranched polyester polyol of second generation modified with polylactic acid in these blends. The blends were prepared in a torque rheometer. In all cases the weight ratio of thermoplastic starch/polylactic acid was 50/50 wt%. The proportions of the compatibility were 5 wt%, 10 wt% 15 wt%, and 20 wt% regard to the total amount of thermoplastic starch and polylactic acid. The blends were characterized by infrared, thermogravimetric, differential scanning calorimetry, X-ray diffraction, scanning electron microscopy and rheological analyses. Torque value decreased with the proportion of compatibilizing. Therefore, the compatibilizing also acted as plasticizing. By infrared analysis was observed that the increasing on the compatibilizing content enhanced the intensity of the signals corresponding to OH and C=O groups. By X-ray diffraction and differential scanning calorimetry analyses was observed a reduction of the crystallinity of the blends obtained with compatibilizing. By rheological analysis was evidenced the formation of a microstructure, which is able to elastically deform.
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