Comparative study of the effect of TiO2 and ZnO on the crystallization of PHB

Abstract

RESUMOForam preparados compósitos PHB/TiO 2 e PHB/ZnO num misturador interno de laboratório, a cristalização foi investigada por calorimetria exploratória diferencial (DSC), com taxas de aquecimento e resfriamento entre 5 e 30 °C/min e a superfície de fratura de seletas composições analisada por microscopia eletrônica de varredura (MEV). Através das imagens de MEV foi observado que as nanopartículas de ZnO e TiO 2 estão bem dispersas na matriz de PHB. Por DSC, observou-se que a adição de TiO 2 e ZnO modificou a temperatura e taxa de cristalização do PHB, sem afetar significativamente a cristalinidade total. Em geral, a adição da carga TiO 2 promoveu alterações mais significativas na matriz de PHB, comportando-se como um agente nucleante. Palavras-chave: PHB, cristalização, TiO 2 , ZnO, DSC. ABSTRACTPHB/TiO 2 and PHB/ZnO compounds were prepared in a laboratory internal mixer. Crystallization was investigated by differential scanning calorimetry (DSC) with heating and cooling rates ranging from 5 to 30 ºC/min. Fractured surface of selected samples was analysed by scanning electron microscopy (SEM). From the SEM images, it was observed that ZnO and TiO 2 nanoparticles were properly dispersed in the PHB matrix. DSC studies revealed that the addition of TiO 2 and ZnO changed the temperature and crystallization rate but did not affect the total crystallinity significantly. In general, TiO 2 behaved as nucleating agent greatly influencing the PHB crystallization.

Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) Production by Rhodospirillum rubrum Using a Two-Step Culture Strategy

“…As reported, PHB was thermally unstable and possibly degradable when submitted to usual process conditions. Its T d was about 220°C which was near its melting point (about 180°C) [35,36]. Compared with PHB, the PHBV obtained in the study had a higher T d (279.236°C), which was far apart from its melting temperature T m .…”

A promising sustainable PHB‐ZnO composite for development of biodegradable filaments

“…To overcome this limitation, it is common to insert fillers, such as oxides, for example, TiO 2 and ZnO, as mentioned in the literature. 50 In this work, for intermediate ZnO contents, between 1% and 4% of ZnO, X c increased, indicating that ZnO may have acted as a nucleating agent. Such an increase was also seen in the literature for PHB/nano ZnO.…”

“…Jaques et al reported the same peak displacement when adding TiO 2 to the PHB matrix, which is justified as a possible nucleating activity. 50 Figure 6(B) showed that the green composites had a single event related to the melting stage similar to the pristine PHB, except for the PHB-0.5% ZnO sample, which had the most intense peak with a little shift to the left. That melting behavior might be due to the ZnO acting as a non-nucleation agent for ZnO loadings higher than 0.5%.…”

Cationic Cyclopentadienyliron Complex as a Novel and Successful Nucleating Agent on the Crystallization Behavior of the Biodegradable PHB Polymer

“…These results could be attributed to the presence of the strong interaction between the organoiron centers (CpFe + ) and the PHB matrix. As can be seen in Figure 5 , the appearance of the crystallization peaks of the PHB nanocomposites became sharper and narrower compared with those of the pure PHB, which demonstrated that the CpFe + acts as an efficient nucleating agent and suggested that the PHB crystallization occurs through a heterogeneous nucleating mechanism [ 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 ]. Therefore, the values of the ∆H c for all the PHB nanocomposites were higher than those of the pure PHB.…”

“…Examples of these nucleating agents have included the following: NH 4 Cl [ 18 ], melamine [ 19 ], boron nitride [ 20 , 21 ], talc [ 22 , 23 ], cyanuric acid [ 24 ], cyclodextrin [ 25 ], lignin [ 26 ], and thermally reduced graphene (TRG) [ 27 ]. Recent examples have incorporated nanofillers, such as multi-walled carbon nanotubes [ 28 , 29 ], TiO 2 , and ZnO nanoparticles [ 30 ], graphite nanosheets [ 31 ], and WS 2 inorganic nanotubes [ 32 ].…”