Search Results (494)

Polylactic acid (PLA) is a promising biodegradable polymer whose widespread application is hindered by inherent brittleness. Polyethylene glycol (PEG) is a common plasticizer, but the effects of intermediate molecular weights, such as 4000 g/mol, on the coupled thermal, mechanical, and rheological properties of PLA remain insufficiently understood. This study presents a comprehensive analysis of PLA plasticized with 0–20 wt% PEG 4000, employing differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), and rheology. DSC confirmed excellent miscibility and a significant glass transition temperature (T_g) depression exceeding 19 °C for the highest concentration. A complex, non-monotonic evolution of crystallinity was observed, associated with the formation of different crystalline forms (α′ and α). Critically, DMA revealed that the material’s thermo-mechanical response is dominated by its thermal history: while the plasticizing effect is masked in highly crystalline, as-cast films, it is unequivocally demonstrated in quenched amorphous samples. The core finding emerges from a targeted rheological investigation. An anomalous increase in melt viscosity and elasticity at intermediate PEG concentrations (5–15 wt%), observed at 180 °C, was systematically shown to vanish at 190 °C and in amorphous samples. This proves that the anomaly stems from residual crystalline domains (α′ precursors) persisting near the melting point, not from a transient molecular network. These results establish that PEG 4000 is a highly effective PLA plasticizer whose impact is profoundly mediated by processing-induced crystallinity. This work provides essential guidelines for tailoring PLA properties by controlling thermal history to optimize flexibility and processability for advanced applications, specifically in melt-processing for flexible packaging. Full article

Biopolymer-based films have attracted increasing attention as sustainable and bioactive materials for wound management. Among them, chitosan (CTS) and starch (ST) blend represent promising candidate due to their natural origin, biodegradability, and intrinsic biological activity; however, their mechanical weakness and limited stability necessitate additional modification. This study reports the development and characterization of CTS-ST thin films crosslinked with dialdehyde alginate (ADA), synthesized via controlled oxidation. Two ADA variants differing in aldehyde group content were prepared to investigate the effect of crosslinking on the structural, physicochemical, and biological performance of the materials. The films were fabricated by blending 2% w/v CTS and ST in varying mass ratios (75/25, 50/50, and 25/75), followed by the addition of ADA (5% w/w) and glycerol (5% w/w) as a plasticizer. The mixtures were then cast onto plates and dried under ambient conditions. Comprehensive characterization included Fourier-transform infrared spectroscopy, moisture content analysis, contact angle measurements, antioxidant activity assay, hemolysis testing, and cytotoxicity evaluation using human keratinocyte cells. The results demonstrated that both the ADA variant and CTS/ST ratio significantly influenced crosslinking efficiency, hydrophilicity, and antioxidant behavior. All samples exhibited non-hemolytic behavior and no significant cytotoxic effects, indicating their favorable biocompatibility. The combination of biostability, antioxidant ability, and absence of cytotoxic effects highlights the potential of ADA-crosslinking CTS/ST films for further development as wound dressing materials and other biomedical applications. Full article

The growing global production of plastic, which reached 460 million tonnes in 2022 and has projections of 5.4 million tonnes of waste by 2050 without intervention, has created a severe environmental crisis that demands the development of sustainable alternatives. In this context, this study aims to characterise biodegradable films based on cassava starch and gellan gum, combining microstructural and mechanical properties with the evaluation of thermo-optical parameters. An important advance was the pioneering application of a self-normalised photoacoustic technique, used for the first time to measure thermal diffusivity (0.0013 ± 0.0002 cm²/s) and optical absorption coefficients (at 660 nm) as a function of different concentrations of aniline blue. The results validate the material, which showed high solubility (89.23 ± 1.03%) and crystallinity of 27.40 ± 1.68%. The film demonstrated remarkable biodegradability, losing almost all of its weight (98.30 ± 1.01%) in just 15 days. The measurement of the optical absorption coefficients (at 660 nm) confirmed a linear relationship with the concentration of aniline, validating Beer–Lambert’s law and providing the absorptivity of the dye within the solid matrix—something inaccessible with conventional methods. In conclusion, these films offer significant potential as a viable ecological substitute for single-use plastics, contributing significantly to mitigating the global impact of plastic waste. Full article

Every year, crustacean shell waste amounts to nearly 8 million tons worldwide, representing both an environmental challenge and a valuable resource. Crustacean shells can be repurposed as raw material for products in various industries, including agriculture, construction, and biomedicine. They are a valuable resource for creating functional materials due to their high content of chitin, protein, and calcium carbonate. These compounds can be extracted and processed to create various products, such as the biopolymer chitosan, antioxidants like astaxanthin, and adsorbents for water treatment, aligning with a circular economy approach by converting waste into valuable by-products. Chitosan films from crustacean waste are promising active packaging materials developed over the last decade, featuring enhanced antimicrobial and antioxidant properties. Extensive research confirms that crustacean shell waste is an excellent, low-cost adsorbent for removing heavy metals from water. This review analyzes current trends and opportunities for crustacean shell waste utilization in packaging materials and wastewater treatment. Key applications include replacing conventional plastic in biodegradable packaging and improving water treatment, which enhances resource efficiency and minimizes environmental pollution. Full article

Sizing is a critical operation in woven fabric production, as it enhances weaving efficiency by improving warp yarn performance. Conventional sizing agents include maize starch, polyvinyl alcohol (PVA), and commercial carboxymethyl cellulose (CMC). In this study, a low-cost and biodegradable carboxymethyl cellulose derived from wheat straw (CMC_ws) was investigated as an alternative sizing agent for cotton open-end yarns with a count of Nm 12.2. The high degree of substitution (DS = 1.23) of CMC_ws indicates extensive carboxymethylation, which enhances the polymer’s hydrophilicity and solubility in water. This, in turn, contributes to a higher apparent viscosity (η = 903.03 cP at 300 s⁻¹), reflecting stronger molecular chain interactions and better film-forming ability. CMC_ws was applied using a high-pressure squeezing technique, and its effect on yarn performance was evaluated in terms of tensile properties, film characteristics, and yarn surface morphology. The results showed that CMC_ws provided a tenacity gain of 28.57%, a hairiness reduction of 54.34%, and an abrasion resistance gain of 37.14%. These values fall within acceptable industrial ranges and are comparable to those obtained using conventional sizing agents. Furthermore, the optimized CMC_ws formulation, containing plasticizer and lubricant additives, exhibited good desizing efficiency, with effective removal achieved in hot water. The findings indicate that wheat-straw-derived CMC_ws is a viable, sustainable alternative to traditional sizing agents for woven fabric production. Full article

Glycerol-(9,10-trioxolane) trioleate (OTOA) is a promising material that combines good plasticizing properties for PLA with profound antimicrobial activity, which makes it suitable for application in state-of-the-art biomedical and packaging materials with added functionality. In this study, the biodegradation kinetics of PLA + OTOA mixed films under soil conditions was assessed over 180 days. Structural and morphological changes that occurred on the surface and in the volume of the films during degradation were scrutinized using DSC, X-ray diffraction, IR, and UV spectroscopy. Morphological changes were assessed using optical and confocal microscopes. The different behavior of the PLA + OTOA blend films during decomposition in soil is explained by their structure and the rate of release of antibacterial OTOA from the PLA matrix. The decomposition rate constants were determined for all films, where k_d for PLA samples is 28 µm·year⁻¹, for samples containing 10% and 30% OTOA k_d is 2 µm·year⁻¹, and for PLA + 50% OTOA samples k_d = 34 µm·year⁻¹. This is explained by changes in the structure and degree of crystallinity of materials during the process of aging in the soil. These results clarify the biodegradation processes of biomaterials containing antibacterial agents in their structure. Full article

Growing concern over the environmental impact of conventional plastics has driven the development of biodegradable alternatives. In this context, natural polymers such as starch have emerged as sustainable options. Commercial montmorillonite, implemented as a reference nanomaterial, allows for the enhancement of the properties of biodegradable materials. In this study, commercial cassava starch powder plasticized with water and 35% glycerol, along with commercial nanoclay at concentrations of 0%, 2%, and 4%, was used as film reinforcement. The manufacturing process employed extrusion to evaluate the effectiveness of the nanomaterial in improving the mechanical and functional characteristics of the films. Films with varying concentrations of glycerol and nanoclay were produced to determine the optimal formulation by assessing their rheological, thermal, and mechanical properties. These films were subjected to comprehensive analysis using internationally standardised techniques, including Thermogravimetric Analysis (TGA), Differential Scanning Calorimetry (DSC), Fourier Transform Infrared Spectroscopy (FTIR), and morphological characterisation via Scanning Electron Microscopy (SEM). Among the properties evaluated, water vapour permeability (WVTR) was of particular interest. Results showed that higher nanoclay content improved moisture retention, thus enhancing the films’ water barrier properties. Mechanical testing indicated that the film with the highest nanoclay concentration, F-g35-NC4, displayed tensile strength values of 0.23 ± 0.02 MPa and elongation of 66.90% ± 4.85, whereas F-g35-NC0 and F-g35-NC2 exhibited lower values. Conversely, the highest tear resistance was also recorded for F-g35-NC4, reaching 0.740 ± 0.009 kg. Contact angle measurements revealed a hydrophilic tendency, with values of 89.93° ± 8.78°. Finally, WVTR analysis confirmed that increased nanoclay content enhanced moisture retention and improved the water barrier performance, with a value of 0.030 ± 0.011 g/m²·day, supporting potential applications in the packaging sector. Full article

Fresh fruits are inherently prone to postharvest deterioration due to loss of moisture, respiration, mechanical damage, and microbial decay, making quality preservation a persistent challenge across fresh fruit supply chains. While conventional plastic packaging offers barrier protection and cost-efficiency, its environmental footprint, particularly poor biodegradability and increasing incidence of plastic waste necessitates a transition toward more sustainable alternatives. Among these, the use of edible coatings, primarily based on natural biopolymers, have emerged as a versatile strategy capable of modulating transpiration, gas exchange, microbial activity, and sensory quality while addressing environmental concerns. Unlike biodegradable plastic films, edible coatings directly interface with the fruit surface and offer multifunctional roles extending beyond passive protection. This review synthesizes recent advances in edible coatings for fresh fruits, with emphasis on material classes, functional performance, optimization strategies, and analytical evaluation methods. Key findings indicate that polysaccharide-based coatings provide adequate gas permeability but limited moisture resistance, while nanocomposite and multi-component systems enhance water-vapor barrier performance without compromising respiration compatibility. Incorporation of bioactive agents such as essential oils, nanoparticles, and plant extracts further extends shelf life through antimicrobial and antioxidant mechanisms, though formulation trade-offs and sensory constraints persist. The review also highlights critical limitations, including variability in barrier and mechanical properties, challenges in industrial-scale application, insufficient long-term validation under commercial cold-chain conditions, and regulatory uncertainty for active formulations. Future research priorities are identified, including mechanistic transport–physiology integration, standardized performance metrics, scalable application technologies, and life-cycle-informed material design. Addressing these gaps is essential for transitioning edible coatings from experimental sustainability concepts to robust, function-driven solutions for fresh-fruit preservation. Full article

Growing concern about the environmental impact of traditional packaging has driven the development of biodegradable edible films made from natural and functional biopolymers. Various by-products generated during harvesting can be subjected to valorization. Potato, a tuber with high starch content, and carrot, rich in β-carotene, represent important sources of polymeric matrix and bioactive compounds, respectively. Similarly, the use of biodegradable plasticizers such as pectin and polysaccharides derived from nopal mucilage is a viable alternative. This study assessed the physical and chemical properties of edible films composed of potato starch (PS), cactus mucilage (NM), carrot extract (CJ), citrus pectin (P), and glycerin (G). The films were produced by means of casting, with three mixtures prepared that had different proportions of CJ, P, and PS. The experiments were adjusted to a simple mixture design, and the data were analyzed in triplicate, using Pareto and Tukey diagrams at 5% significance. Results showed that adding CJ (between 5 to 6%), P (between 42 to 44%) and PS (between 43 to 45%) significantly affects all of the evaluated physical and chemical properties, resulting in films with luminosity values greater than 88.65, opacity ranging from 0.20 to 0.54 abs/mm, β-carotene content up to 26.11 μg/100 g, acidity between 0.22 and 0.31% and high solubility with a significant difference between treatments (p-value < 0.05) and low water activity (around of 0.47) (p-value > 0.05). These characteristics provide tensile strength up to 5.7 MPa and a suitable permeability of 1.6 × 10⁻² g·mm/h·m²·Pa (p-value < 0.05), which ensures low diffusivity through the film. Similarly, increasing the CJ addition enables the functional groups of the other components to interact. Using carrot extract and potato starch is a promising approach for producing edible films with good functional qualities but with high permeability. Full article

This work investigates the modification of poly(lactic acid) (PLA) film properties for food packaging applications through the incorporation of modified gelatin (Gel-mod) and a choline chloride/glycerol deep eutectic solvent (DES). PLA/Gel-mod/DES materials were melt-processed and evaluated with respect to structure, morphology, thermal and mechanical behavior, processability, wettability, barrier performance, and compostability. Two incorporation routes were investigated for adding Gel-mod into the PLA matrix: direct incorporation and masterbatch preparation. FTIR and SEM analyses confirmed improved interfacial interactions and more homogeneous dispersion when Gel-mod was directly incorporated, compared with the masterbatch route. DES acted as an effective plasticizer and nucleating agent, reducing Tg, increasing crystallinity, and enhancing processability while maintaining thermal stability. Mechanical properties decreased relative to neat PLA, primarily due to increased crystallinity and chain scission. PLA_4Gel-mod demonstrated a more balanced performance, with higher elongation at break and improved processability than the other formulations, likely due to its single processing cycle, which minimized PLA degradation. Increased hydrophilicity led to higher water vapor transmission rates, correlating with accelerated biodegradation. Overall, the synergistic incorporation of DES and gelatin provides a viable strategy to tailor PLA properties, enabling the development of compostable packaging films suitable for sustainable food contact applications. Full article

(1) Background: The replacement of petroleum-based plastics with sustainable biopolymer films is crucial for global food preservation. Biopolymers like zein and pectin offer biodegradable and compostable alternatives but often require functionalization. This study develops and characterizes a novel antioxidant film by incorporating silver microparticles (AgMp) derived from the valorization of an agricultural waste product: pecan nutshell extract. (2) Methods: AgMp were synthesized via green reduction method using the extract. These bioactive microparticles were subsequently incorporated into a zein/pectin polymeric solution using the solvent-casting technique. The particles and the active films were characterized using FTIR, SEM, and antioxidant assays (ABTS, DPPH, and FRAP). (3) Results: The extract and AgMp exhibited a potent antioxidant activity (100% inhibition for ABTS/DPPH). SEM analysis confirmed the scale of 0.545–1.033 µm, classifying the material as microparticles. The final films retained a dose-dependent antioxidant activity (66.78% for ABTS and 53.67% for DPPH). (4) Conclusions: This work validates that pecan nutshell extract as an effective green reducing and capping agent. The resulting film possesses significant antioxidant activity, offering a promising alternative for active food packaging applications, such as bioactive pads or inserts. Full article

Most polymeric plastics used as food packaging are obtained from petroleum or made with non-biodegradable synthetic molecules, which slowly degrade and leach into the environment, resulting in the accumulation of microplastics along the trophic chains. To mitigate these impacts, biodegradable packaging derived from agro-industrial biomass residues has emerged as a promising alternative. In this study, bio-based methylcellulose films reinforced with cellulose nanocrystals (CNCs) extracted from low-quality coffee beans were developed and fully characterized. The extracted CNCs presented a needle-like morphology, with an average height of 7.27 nm and a length of 221.34 nm, with 65.75% crystallinity, were stable at pH 7–8, and presented thermogravimetric mass loss of 8.0%. Methylcellulose films containing 0.6% w/w of CNC were produced by casting and characterized in terms of thermal, mechanical, and optical properties. Notably, the incorporation of CNCs resulted in significantly more flexible and less rigid films, as evidenced by the higher elongation at break (57.90%) and lower Young’s modulus (0.0015 GPa) compared to neat methylcellulose film. The tensile strength was not affected (p > 0.05). Additionally, the MCNC 0.6% films effectively blocked UV light in the 200–300 nm range without compromising transparency. Altogether, these findings underscore the MCNC 0.6% film as a flexible, biodegradable packaging material suitable for food industry application. Full article

Recent studies have focused on the development of food packaging films based on biopolymers, with polysaccharides being at the forefront due to their abundant availability in food and agricultural by-products. Therefore, it was the aim of this work to prepare and characterize conjugated biopolymeric films using starch, galactomannans and buriti oil (BO), with the latter acting as a partial or integral replacement for glycerol as a plasticizer. The addition of BO to either the starch or the conjugated starch–galactomannan film formulations led to distinct interactions between the components and consequently to films with distinct properties. The addition of both BO and galactomannan to starch hindered retrogradation, characterized by a diminished degree of crystallinity in comparison to the film containing only starch, attesting the stabilization of the starch molecular structures in its interaction with galactomannan molecules and with the emulsified BO. The analyses of films’ mechanical properties demonstrated that the added BO did not act as a plasticizer, leading to increased tensile strength and elastic modulus and decreased elongation at break in all formulations. Overall, the films containing starch presented lower mechanical resistance than the ones based on galactomannan. All formulations led to biodegradable films, with those with BO taking longer to degrade. Full article

This review provides an in-depth look at the key process limitations and (structural) defects encountered in the production of polymer films via film blowing extrusion technology. Film blowing is the most widely used method for producing plastic films across various industries, with its increasing demand driven by flexible packaging needs. Overcoming the challenges of this complex production process is essential for ensuring high quality and meeting the growing demand for modern applications, taking into account polymer circularity. In the first part of this paper, the focus is on conventional films, generally polyolefin single-layer films. Common defects such as bubble instability, gauge variations, wrinkles, melt fractures, optical defects, blocking, and surface imperfections like fish eyes are discussed. The most important causes behind these issues are elaborated on, including various molecular and processing parameters, with this paper also offering practical mitigating strategies. In the second part, the specific process limitations and defect types associated with emerging sustainable film technology are focused on, covering films made from recycled materials, biodegradable polymers, polymer blends, and multilayer and machine-direction oriented (MDO) films. While these innovative films offer significant advantages in terms of sustainability and property enhancement, they also present additional points of attention. Also, effective mitigation strategies for addressing these technical issues are incorporated. Overall, this study provides a comprehensive review of film blowing defects, contributing to improved process control, reduced waste, and the production of high-quality films that meet modern requirements. By identifying the root causes of common defects and discussing viable solutions, this review plays a key role in advancing the efficiency, consistency, and sustainability of film blowing technology by presenting a combined experimental and modelling approach that can be used in future work. Full article

Growing environmental concerns and the need for sustainable materials have accelerated the search for biodegradable alternatives to food packaging. Since nearly half of global plastic production is dedicated to food packaging, and less than 5% is recyclable, developing eco-friendly solutions is urgent. Biopolymeric films enriched with microalgae and cyanobacteria have emerged as promising options due to their bioactive properties. This study screened 38 film-forming formulations combining different biopolymers with varying concentrations of Spirulina (0–5%) to identify the most suitable candidates based on physical and visual characteristics. Films produced with pectin and hydroxypropylmethylcellulose (HPMC) matrices were selected for detailed characterization, including physicochemical, optical, mechanical, thermal, barrier, surface, and functional group analyses, as well as antioxidant activity. The highest elongation at break (%) was observed in the control HPMC film (16.5 ± 3.85), whereas the lowest value was recorded for the pectin film containing 1% Spirulina (2.75 ± 0.49). In parallel, the highest thickness (mm) was found in the pectin film with 5% Spirulina (0.153 ± 0.018), while the lowest thickness occurred in the HPMC film incorporating 1% biomass (0.076 ± 0.004). The incorporation of Spirulina decreased solubility and moisture content while increasing opacity. HPMC-based films demonstrated superior mechanical strength, thermal stability, barrier performance, and significantly higher antioxidant activity compared to pectin films. Antioxidant activity increased with biomass concentration, peaking at 5% (HPMC: 320.08 ± 35.7 µmol TE/g; pectin: 36.92 ± 7.63 µmol TE/g). Overall, the HPMC film containing 1% Spirulina showed the best balance of properties, including mechanical behavior and antioxidant performance, indicating strong potential for food packaging applications, particularly for protecting light-sensitive and oxidation-prone foods. Full article