Blendas poliméricas biodegradáveis de PHB e PLA para fabricação de filmes

Abstract

O poli(hidroxibutirato) - PHB - e o poli(ácido lático) - PLA - são dois poliésteres termoplásticos com grande potencial para uso em aplicações industriais, sendo viáveis nos principais métodos de processamento e totalmente biodegradáveis. Porém, devido às suas propriedades mecânicas limitadas, necessitam de modificações para melhorar seu desempenho e tornarem-se industrialmente competitivos. Foram estudadas propriedades e características destes dois polímeros e suas misturas poliméricas, avaliando a possibilidade do uso na preparação de filmes finos por extrusão para embalagens. Verificou-se a possibilidade de produção de filmes finos de misturas PHB/PLA, através das técnicas de extrusão de filmes, planos e tubulares soprados. Porém, para viabilizar a produção industrial destes filmes, modificações devem ser realizadas no processo de produção e/ou no preparo da mistura polimérica através da aditivação, com o objetivo de reduzir a alta adesividade dos filmes durante o seu processamento.

Production and characterization of films containing poly(hydroxybutyrate) (PHB) blended with esterified alginate (ALG‐e) and poly(ethylene glycol) (PEG)

“…The rigid and fragile character of PHB can be observed by the results of the tensile tests, which can be attributed to low deformation of the material, sudden rupture and a high elastic modulus, all of which is associated with its high degree of crystallization . Factors such as low nucleation density due to the high purity of PHB lead to the formation of large spherulites and cracks that culminate in a brittle material.…”

On the Use of PLA-PHB Blends for Sustainable Food Packaging Applications

“…In fact, PLA-PHB blends with a high fraction of PHB (up to 60 wt %) behave as brittle polymeric systems and break at very low elongations (<3%), while PLA-PHB blends with lower than 40 wt % of PHB can be stretched up like typical thermoplastic polymers [ 52 ]. Similarly, the impact resistance of PLA-PHB 75:25 results higher than that of homopolymers [ 107 ]. Thus, it seems that a synergic effect take place in PLA-PHB 75:25 blend since this blend formulation showed higher mechanical performance than neat PLA [ 40 ], while the PHB high rigidity is reduced [ 52 ].…”

“…It should be mentioned that the performance of PLA and PHB as well as their blends could suffer changes over time due to the inherent biodegradability of both polymeric matrices [ 93 ]. In this context, tensile tests were performed after two years of processing PLA, PHB and PLA-PHB blends, and this aging study have showed significantly increase in ductility over the ageing time [ 107 ]. Concerning their application in short term applications intended for the food packaging field, the performance of the packaging material should be guaranteed at least during the food’s shelf life [ 108 ].…”

Development of active PHB/PEG antimicrobial films incorporating clove essential oil

“…PHB is a thermoplastic polymer obtained from renewable natural sources that shown characteristics of biodegradability, biocompatibility, UV resistance and properties similar to the synthetic polypropylene [12][13][14] . However, the high crystallinity of PHB makes it very rigid and brittle, limiting its applications [15,16] . To overcome this limitation, plasticizers are added to the PHB.…”