Film blowing of PHBV blends and PHBV‐based multilayers for the production of biodegradable packages

Abstract

Poly(hydroxy butyrate‐co‐valerate) (PHBV) is a biodegradable polymer that is difficult to melt process into films. Such difficulty is mirrored in the lack of literature on film blowing of PHBV‐ or PHBV‐based materials. To circumvent this problem, 70/30 wt % blends of PHBV with a biodegradable compound (PBSebT), or with poly(butylene adipate‐co‐terephtalate) (PBAT), were prepared and tested for extrusion film blowing. Both blends showed a similar rheological pattern at 175°C, which is the maximum processing temperature with tolerable thermal degradation. Blending stabilized the film bubbles, thus widening the processing window. However, film properties such as tensile modulus, strain at break and tear resistance remained isotropic and crystallinity characteristics in the machine and transverse directions were generally similar. To bypass the thermal degradation associated with polymer blending, PHBV/PBAT films were coextruded. These showed enhanced functional properties when compared with films blown from blends. The mechanical properties of bilayered films matched those of films blown from commercial PBAT designed for food packaging. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 42165.

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

“…Their verified biodegradability and biocompatibility, lack of immunogenic and carcinogenic effects, and lack of toxicity promote the use of PHAs in the biomedical field . Abundant literature has been published on new methods for improving the synthesis and characteristics of PHAs for the biomedical field and food packaging …”

“…Strong barriers for the wide application of PHB are its high brittleness, low crystallization rate, poor thermal stability, and narrow processing window . The thermal degradation of PHB during melt processing and the poor melt strength have been targeted as the main unsolved problems for the fabrication of biomedical devices or packages from PHB by injection or blow molding . Indeed, the melting temperature ( T m ) of PHB is close to its onset degradation temperature, and repeated exposure to high shear or compression efforts and high temperature during the melt processing may lead to the thermal degradation of PHB, with a subsequent decrease in its performance .…”

Bio‐based blends from poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) and natural rubber for packaging applications

“…The increased viscosity of PHBV at higher rubber loading (15–25%) was probably due to increased formation of entanglement‐derived locked‐in loops of PHBV in localized NR networks and possible grafting of PHBV to rubber. The low melt viscosity and melt strength make PHBV too fluid to sustain its shape during thermal processing . The enhanced viscosities of the higher NR content PHBV blends are comparable to some commercial packaging materials, such as PP (600 Pa s −1 ).…”

Desarrollo y caracterización de formulaciones poliméricas biodegradables y termoconformables para envasado

“…Se demuestra que las propiedades mecánicas de las películas fabricadas por mezclado en fundido y posterior extrusión conducen a películas relativamente inelásticas con una baja elongación a la rotura, limitando la aplicación de estos materiales para el procesado industrial. Dado este contexto, se han reportado un amplio número de investigaciones centradas en el mezclado del PHBV con otros polímeros [17,20,23,24,[103][104][105][106][107][108][109][110]. Desafortunadamente, la mayoría de las mezclas de PHBV no son exitosas como consecuencia de la inmiscibilidad del PHBV con la mayoría de los polímeros.…”

“…El elevado grado de cristalinidad que posee el PHBV resulta en una ventana de procesado estrecha cuando se compara con otros biopoliésteres [64,109,[111][112][113][114].…”