Miguel Aldas

Thermoplastic starch (TPS) and polyvinyl alcohol (PVA) blends were prepared over the full compositional range (0–100 wt% PVA) by solvent-free twin-screw extrusion and injection molding. This enabled a systematic evaluation of structure–performance–disintegration relationships under industrially relevant conditions. The blends exhibited clear composition-dependent trends in thermal and mechanical behavior. Increasing PVA content from 0 to 100 wt% raised the onset degradation temperature (T5%) from 160.5 °C to 290.5 °C and increased crystallinity from near zero to 12.24%. Mechanically, the response evolved from a rigid TPS-rich state to a ductile PVA-rich one. FTIR and SEM analyses indicated partial compatibility, with limited molecular-level interactions leading to morphologically homogeneous but only partially miscible blends. Under simulated composting conditions, all formulations showed substantial physical disintegration. PVA-rich blends (≥60 wt%) disintegrated rapidly (>80% mass loss within two days), primarily by dissolution rather than microbial degradation. Overall, this work provides a comprehensive, scalable assessment of solvent-free TPS/PVA blends, clarifies their limited compatibility under melt processing, and demonstrates how composition can be used to tailor structure, performance, and disintegration behavior across the full compositional range.

La contaminación ambiental generada por plásticos de un solo uso constituye un desafío global que impulsa el desarrollo de materiales biodegradables basados en recursos renovables. En este estudio se desarrollaron y caracterizaron biopelículas biodegradables mediante la técnica de casting, empleando harina de cáscara de chocho (Lupinus mutabilis) y almidón de yuca (Manihot esculenta), subproductos agroindustriales abundantes en Ecuador. Se aplicó un diseño experimental factorial con el objetivo de optimizar la formulación y evaluar la influencia de los componentes sobre las propiedades fisicoquímicas, mecánicas y de biodegradabilidad del material. Las biopelículas obtenidas presentaron espesores entre 0.15 y 0.43 mm, contenidos de humedad de 12.83–24.85% y solubilidades en agua comprendidas entre 21.94 y 48.66%. La permeabilidad al vapor de agua se situó en el orden de 10⁻⁷ g·mm/cm²·h·Pa, valores significativamente superiores a los del polietileno de baja densidad (LDPE) utilizado como control (3.15 × 10⁻¹² g·mm/cm²·h·Pa), reflejando la naturaleza hidrofílica de la matriz biopolimérica. Entre las formulaciones evaluadas, el tratamiento T3 evidenció el mejor compromiso entre propiedades, mostrando una menor permeabilidad al vapor de agua en comparación con las demás formulaciones. Desde el punto de vista mecánico, las biopelículas alcanzaron resistencias máximas a la tracción de hasta 6.02 N y deformaciones máximas de 3.99 mm, valores adecuados para aplicaciones que no requieren alta carga estructural. Los ensayos de integridad en simulantes alimentarios (agua destilada y aceite de oliva) demostraron una mayor estabilidad estructural y baja permeabilidad en medios grasos, mientras que en medio acuoso se observó una pérdida progresiva de integridad. Las pruebas de biodegradabilidad en suelo evidenciaron una degradación significativa del material en un periodo de 28 días. Con base en su comportamiento mecánico, estabilidad en medios lipídicos y rápida biodegradación, se propone el uso potencial de estas biopelículas como material biodegradable para separadores entre láminas de queso mozzarella. En conjunto, los resultados indican que, particularmente la formulación T3, estas biopelículas representan una alternativa técnica y ambientalmente viable a los plásticos convencionales, contribuyendo a la economía circular mediante la valorización de residuos agroindustriales y el desarrollo de materiales sostenibles de origen local.

The design of sustainable polymer systems with tunable properties is essential for next-generation functional materials. This study examines the influence of a phenol-free modified rosin resin (Unik Print™ 3340, UP)—a maleic anhydride- and fumaric acid-modified gum rosin—on the structural, thermal, rheological, and mechanical behavior of four poly(lactic acid) (PLA) grades with different molecular weights and crystallinity. Blends containing 3 phr of UP were prepared by melt compounding. Thermogravimetric analysis showed that the incorporation of UP did not alter the thermal degradation of PLA, confirming stability retention. In contrast, differential scanning calorimetry revealed that UP affected thermal transitions, suppressing crystallization and melting in amorphous PLA grades and shifting the crystallization temperature to lower values in semi-crystalline grades. The degree of crystallinity decreased for low-molecular-weight semi-crystalline PLA but slightly increased in higher-molecular-weight samples. Mechanical tests indicated that UP acted as a physical modifier, increasing toughness by over 25% for all PLA grades and up to 60% in the amorphous, low-molecular-weight grade. Rheological measurements revealed moderate viscosity variations, while FESEM analysis confirmed microstructural features consistent with improved ductility. Overall, UP resin enables fine tuning of the structure–property relationships of PLA without compromising stability, offering a sustainable route for developing bio-based polymer systems with enhanced mechanical performance and potential use in future biomimetic material designs.

The massive use of plastics has raised growing environmental concerns, including microplastic (MP) pollution. While most studies have focused on MPs in aquatic environments, research on airborne microplastics has gained increasing attention in recent years. This review discusses the sampling, analytical, and identification techniques used for MPs, with a particular focus on PM2.5 and PM10 fractions, which have been scarcely addressed in the literature. The main active and passive sampling methods, sample preparation protocols, MP quantification approaches, and chemical characterization techniques applied to airborne plastic particles are compiled. Attention is given to the influence of meteorological conditions on transport and deposition, as well as to the predominant sources of primary and secondary microplastics in both indoor and outdoor environments. The analysis identifies the main research challenges, particularly in the detection of microplastics and in the standardization of protocols. The review highlights the need for standardized methodologies to advance reliable quantification and to better understand the environmental implications of MPs.

Bacterial cellulose (BC) is emerging as an attractive large-scale polymer due to its superior properties. The dominant static culture for BC fermentation by bacteria or microbial consortium results in low productivity. Agitated culture, as an industrially projected technique, has been widely investigated but exclusively for cellulose-producing bacterial strains. Addressing this concern and evaluating the potential of residues as feedstock, this study highlights the utilization of microbial consortium BA2 and seven agro-industrial wastes including cocoa husks, sugarcane bagasse and others. Remarkably, rice bran (RB) appears as a promising substrate, achieving 2.14 g/L (dry basis) and outperforming the traditional HS medium, evident from a 15-day fermentation. A complex interplay between oxygen availability, glucose consumption and BC yield was revealed; while orbital and magnetic stirring with forced air ventilation (AFV) showed low BC yields and early biomass saturation, 4.07 g/L (dry basis) was targeted by magnetic stirring at 100 rpm from the start using only headspace air. However, beyond controlled operating conditions, mechanical agitation and favorable cellulose adhesion to metal in the stirred tank bioreactor negatively affect BC yield. This pattern uncovers the need for a further approach to the design of bioreactors when the microbial consortium is considered.

Biodegradable materials based on poly (lactic acid) (PLA) and a phenolic free modified rosin resin were obtained and studied to control the biodegradability under composting conditions of the materials. The resin was blended in concentrations of 1, 3, 5, 10, and 15 parts per hundred (phr) of base polymer using industrial plastic processing techniques. Additionally, to study the effect of the resin on the compatibility of the PLA, the physical performance, water absorption, mechanical behavior, thermal stability, and microstructure of the materials were assessed. The resin incorporation decreased the resistance to thermal degradation of the resultant material, and the composting disintegration rate was slowed down with the increasing content of the resin. The water diffusion was delayed, and the diffusion and corrected diffusion coefficients decreased with the rising content of UP. The mechanical properties tend to decrease while a saturation effect was observed for contents higher than 3 phr of resin. The optimal amount of resin that can be added to achieve good interaction with PLA matrix, complete miscibility, and good material cohesion is 3 phr.

Poly(butylene succinate) (PBS) is one of the contaminants in the Poly(ethylene terephthalate) (PET) recycling process. It is known that high contents of PBS in PET significantly reduce PET properties, but the effect of low contents on PET has yet to be studied. This work studied the influence of low contents of PBS on recycled PET. Five formulations of PBS in PET were prepared, and the properties of relative affinity, mechanical, thermal, and disintegration under composting conditions were assessed. The solubility parameter indicated that PET and PBS are miscible. However, FESEM images show slight marks of immiscibility, and the mechanical characterization results showed that PBS, even in low contents, reduced the mechanical properties of recycled PET, which proves that the materials are not miscible in the studied contents. The DSC results indicated that PBS could not be quickly detected in PET. However, its presence can be inferred by the reduction in PET crystallization degree. Finally, the presence of PBS up to 15 wt.% does neither affect the disintegration under composting conditions nor the thermal stability of recycled PET. The drop in mechanical properties shows that PBS must be removed from the PET waste stream to preserve the quality of the material.