Plasticized poly(3‐hydroxybutyrate) with improved melt processing and balanced properties

Abstract

The widespread application of poly(3-hydroxybutyrate) (PHB) in the food packaging and biomedical fields has been hindered by its high brittleness, slow crystallization, poor thermal stability, and narrow processing window. To overcome these limitations, a mixture of biodegradable and biocompatible plasticizers was used to modify PHB. Epoxidized soybean oil (ESO), acetyl tributyl citrate, poly(ethylene glycol) 4000 (PEG4000), and poly(ethylene glycol) 6000 (PEG6000) were tested to improve PHB melt processing and to achieve balanced thermal and mechanical properties. These plasticizers increased the flexibility and decreased the melt viscosity, improving the processability. The tensile strength was maintained within the limit of experimental error for ESO and decreased slightly (6-7%) for the other plasticizers. PEG6000 and ESO delayed the decomposition process of PHB. The plasticizers did not hinder the crystallization, and poly(ethylene glycol)s increased the crystallinity. The change in the interplanar distance and crystallite size, correlated with lamellar stack dimensions, gave more information on the plasticizers' effects in PHB. The blend with 5 wt % ESO was considered suitable for the fabrication of marketable PHB films. This study showed that it is possible to tailor the rheological, thermal, and mechanical behavior of a commercial PHB through the addition of a second plasticizer.

Morpho-Structural, Thermal and Mechanical Properties of PLA/PHB/Cellulose Biodegradable Nanocomposites Obtained by Compression Molding, Extrusion, and 3D Printing

“…Unlike PHB which is crystallized from the processing step, PLA shows a small exothermic crystallization peak during the first heating run at 120.8 • C and a very small crystallinity (Figure 7a, Table 2). Similar results were previously reported [7,10,47]. PHB/PLA blends and nanocomposites exhibit two glass transitions (Figure 7b) because PLA and PHB are not miscible.…”

“…The first degradation peak in the derivative thermogravimetric (DTG) curves comes from the decomposition of the PHB component while the second one is due to hydrolysis and oxidative chain scission of PLA, as resulted from the comparison with the DTG profiles of pure components and literature [44,46]. A small shoulder was noticed in the DTG curves at about 195 • C. This is probably due to the release of TBC plasticizer from the PHB matrix as mentioned in a previous study on the same type of PHB [47] (Figure 8).…”

Functionalization of poly(3‐hydroxybutyrate) with different thiol compounds inhibits MDM2–p53 interactions in MCF7 cells

“…Similarly, the T 10 and T p values of PI (266 and 283°C, respectively), PII (254 and 275°C, respectively), and PIII (253 and 297°C, respectively) were higher than the corresponding values of PHB and PHB–diol. Thus, we concluded that PI, PII, and PIII were more thermally stable than PHB and PHB–diol . The high residual weights of PI (6.37%), PIII (8.90%), PIV (3.44%), and PV (3.07%) may have been due to the formation of a protective surface film on the polymer bulk, which inhibited further decomposition by raising the final decomposition temperatures .…”

“…The neat PHB curve displayed one degradation step around 200–350°C . The thermal degradation mechanism of PHB involved a random chain scission (β‐elimination) reaction of ester groups to form crotonic acid and its oligomers, whose presence was proven by mass spectroscopy . However, the PHB–diol and PHB–thiol polymers displayed two degradation steps, as shown in the DTG curve in Figure (A) .…”

Bio-Based Epoxy Resin from Epoxidized Soybean Oil

“…ESO is initially used as a plasticizer in industry for poly(vinyl chloride) chlorinated (PVC) rubber, and poly(vinyl alcohol) (PVA) emulsions to improve stability and flexibility [105,106], and ESO is also considered to be potential nontoxic biocompatible plasticizers for poly(3-hydroxybutyrate) (PHB) and polylactic acid (PLA) when combined with other plasticizers [107][108][109]. Moreover, it is an interesting trend to prepare composites of ESO or its homo-polymers with other materials because of their special properties.…”