Poly(hydroxybutyrate)‐based systems behavior on the controlled release of NPK fertilizers

Abstract

Here we investigate the behavior of controlled‐release systems based on poly(hydroxybutyrate) (PHB) to propose an actuation mechanism in a designed environment. Two formulations were produced employing 5% pure NPK fertilizer or 30% of bentonite nanoparticles (Bent) previously modified with NPK. The polymeric composites were obtained by melt processing and their thermal properties evaluated. The release of active compounds was evaluated by conductometric analysis in aqueous solutions at different pHs for 30 days, and the results were modulated by the Korsmeyer‐Peppas model. Also, the systems were evaluated for their biodegradation characteristics using different soil types to generate a decomposition profile. In general, the systems showed a good release control, with 40% and 50% of fertilizer being released in 30 days, depending on the conditions and type of polymeric composite employed. The model indicated a linear release of active compounds in the first 30 days, according to the Fick diffusion. Additionally, the compounds were relatively stable in the first 30 days when exposed to biodegradation, being degraded faster speed after this. The efficiency and applicability of the systems were confirmed by the germination tests, which showed that both systems containing NPK favored plant growth, while the system in which the active agents had been previously incorporated into nanoparticles provided a reduction in the waste of agrochemicals. Thus, a novel mechanism of action for polymeric controlled release systems based on thermoplastic biopolymers was determined, supporting more efficient industrial processes.

Selective localization of organophilic clay Cloisite 30B in biodegradable poly(lactic acid)/poly(3‐hydroxybutyrate) blends

“…However, the melting temperature ( T m ) is lower for the first melting event, related to the PHB matrix, and similar for the second event, common to both PHB and PLA phases. This thermal behavior is known and widely reported in the literature, where the decrease in T m values is mainly associated with the formation of less perfect crystalline structures generated by the thermal degradation process of the PHB phase 25,26 …”

“…This thermal behavior is known and widely reported in the literature, where the decrease in T m values is mainly associated with the formation of less perfect crystalline structures generated by the thermal degradation process of the PHB phase. 25,26 Regarding to the addition of C30B, it is observed that the T m values are increased in relation to pure blend, and the magnitude of these increments is related with the mixing mode. In general, for the compounds where the nanoclay was previously mixed in only one phase, increments of around 5 C can be observed for the two melting peaks, while for the sample simultaneously mixed the T m values are very close to the original blend.…”

Development of Biodegradable PLA/PBAT-Based Filaments for Fertilizer Release for Agricultural Applications

“…Ecovio ® is composed of PLA and poly(butylene adipate co-terephthalate) (PBAT) (Ecoflex ® ) and is a material with mechanical properties similar to those of traditional polymers used for agricultural applications [ 27 , 28 ]. Organophilic bentonite clays stand out among the inorganic nanoparticles applicable to the adsorption of fertilizers and their CRF biodegradable nanocomposites have greater matrix stability which allow for the slow release of agricultural compounds [ 5 , 29 ]. In addition to controlling drug release, nanoparticles can provide improvements in general properties of the composite, such as tensile strength, elastic modulus, flexural strength, flexural modulus [ 30 , 31 ], barrier properties [ 32 ] and thermal stability [ 33 ].…”

Bio‐Based Poly(3-hydroxybutyrate)/Thermoplastic Starch Composites as a Host Matrix for Biochar Fillers

“…Doing so would not only reduce the dependence on petroleum based materials, but would also improve the valorization of the used residual streams. Moreover, the biodegradability of biopolymers makes them favorable to be used as a host material for functional fillers in order to become available through gradual exposure and/or diffusion from the matrix material [2][3][4]. Therefore, the production of slow-release fertilizers based on biopolymers and a functional filler material can become a reality.…”

“…If biochar could successfully be used as a filler to produce biocomposites, an additional advantage emerges in the biochars potential use as a slow release fertilizer. It was recently shown that PHB is indeed an interesting candidate as a matrix for controlled slow release of NPK fertilizers, positively affecting crop growth [4]. At the end of its life, the PHB matrix could even again be co-pyrolyzed with biomass to achieve a bio-oil with favorable characteristics as compared to conventional pyrolysis [23].…”