Sepiolite as a promising nanoclay for nano-biocomposites based on starch and biodegradable polyester

An Overview of Polymeric Nanoplatforms to Deliver Veterinary Antimicrobials

There is an urgent need to find new solutions for the global dilemma of increasing antibiotic resistance in humans and animals. Modifying the performance of existing antibiotics using the nanocarrier drug delivery system (DDS) is a good option considering economic costs, labor costs, and time investment compared to the development of new antibiotics. Numerous studies on nanomedicine carriers that can be used for humans are available in the literature, but relatively few studies have been reported specifically for veterinary pharmaceutical products. Polymer-based nano-DDS are becoming a research hotspot in the pharmaceutical industry owing to their advantages, such as stability and modifiability. This review presents current research progress on polymer-based nanodelivery systems for veterinary antimicrobial drugs, focusing on the role of polymeric materials in enhancing drug performance. The use of polymer-based nanoformulations improves treatment compliance in livestock and companion animals, thereby reducing the workload of managers. Although promising advances have been made, many obstacles remain to be addressed before nanoformulations can be used in a clinical setting. Some crucial issues currently facing this field, including toxicity, quality control, and mass production, are discussed in this review. With the continuous optimization of nanotechnology, polymer-based DDS has shown its potential in reducing antibiotic resistance to veterinary medicines.

Emerging trends in flame retardancy of rigid polyurethane foam and its composites: A review

Owing to the superior thermal insulating attributes of rigid polyurethane foam (RPUF) compared to other insulating materials (expanded and extruded polystyrene, mineral wool), it remains the most dominant insulating material and most studied polymer foam. Like other polyurethane foam, RPUF is highly flammable, necessitating the incorporation of flame retardants (FR) during production to lower combustibility, promoting its continuous use as insulation material in construction, transportation, and others. The popular approaches for correcting the high flammability of RPUF are copolymerization and blending (with FR). The second method has proven to be most effective as there are limited trade-offs in RPUF properties. Meanwhile, the high flammability of RPUF is still a significant hindrance in emerging applications (sensors, space travel, and others), and this has continuously inspired research in the flame retardancy of RPUF. In this study, properties, and preparation methods of RPUF are described, factors responsible for the high flammability of PUF are discussed, and flame retardancy of RPUF is thoroughly reviewed. Notably, most FR for RPUF are inorganic nanoparticles, lignin, intumescent FR systems of expandable graphite (EG), ammonium polyphosphate (APP), and hybridized APP or EG with other FR. These could be due to their ease of processing, low cost, and being environmentally benign. Elaborate discussion on RPUF FR mechanisms were also highlighted. Lastly, a summary and future perspectives in fireproofing RPUF are provided, which could inspire the design of new FR for RPUF.

Biobased composites from agro-industrial wastes and by-products

The greater awareness of non-renewable natural resources preservation needs has led to the development of more ecological high-performance polymeric materials with new functionalities. In this regard, biobased composites are considered interesting options, especially those obtained from agro-industrial wastes and by-products. These are low-cost raw materials derived from renewable sources, which are mostly biodegradable and would otherwise typically be discarded. In this review, recent and innovative academic studies on composites obtained from biopolymers, natural fillers and active agents, as well as green-synthesized nanoparticles are presented. An in-depth discussion of biobased composites structures, properties, manufacture, and life-cycle assessment (LCA) is provided along with a wide up-to-date overview of the most recent works in the field with appropriate references. Potential uses of biobased composites from agri-food residues such as active and intelligent food packaging, agricultural inputs, tissue engineering, among others are described, considering that the specific characteristics of these materials should match the proposed application.

Trends and challenges of biopolymer-based nanocomposites in food packaging

The ultimate goal of new food packaging technologies, in addition to maintaining the quality and safety of food for the consumer, is to consider environmental concerns and reduce its impacts. In this regard, one of the solutions is to use eco-friendly biopolymers instead of conventional petroleum-based polymers. However, the challenges of using biopolymers in the food packaging industry should be carefully evaluated, and techniques to eliminate or minimize their disadvantages should be investigated. Many studies have been conducted to improve the properties of biopolymer-based packaging materials to produce a favorable product for the food industry. This article reviews the structure of biopolymer-based materials and discusses the trends and challenges of using these materials in food packaging technologies with the focus on nanotechnology and based on recent studies.

Green Nanocomposites Based on Thermoplastic Starch: A Review

The development of bio-based materials has been a consequence of the environmental awareness generated over time. The versatility of native starch is a promising starting point for manufacturing environmentally friendly materials. This work aims to compile information on the advancements in research on thermoplastic starch (TPS) nanocomposites after the addition of mainly these four nanofillers: natural montmorillonite (MMT), organically modified montmorillonite (O-MMT), cellulose nanocrystals (CNC), and cellulose nanofibers (CNF). The analyzed properties of nanocomposites were mechanical, barrier, optical, and degradability. The most important results were that as the nanofiller increases, the TPS modulus and strength increase; however, the elongation decreases. Furthermore, the barrier properties indicate that that the incorporation of nanofillers confers superior hydrophobicity. However, the optical properties (transparency and luminosity) are mostly reduced, and the color variation is more evident with the addition of these fillers. The biodegradability rate increases with these nanocompounds, as demonstrated by the study of the method of burial in the soil. The results of this compilation show that the compatibility, proper dispersion, and distribution of nanofiller through the TPS matrix are critical factors in overcoming the limitations of starch when extending the applications of these biomaterials. TPS nanocomposites are materials with great potential for improvement. Exploring new sources of starch and natural nano-reinforcement could lead to a genuinely eco-friendly material that can replace traditional polymers in applications such as packaging.

Cellulose nanofibrils reinforced PBAT/TPS blends: Mechanical and rheological properties

Poly(butylene adipate-Co-terephthalate)/thermoplasticized starch PBAT/TPS blends are among the most produced biodegradable plastic for wide application packaging, sharing more than 20% of the global production capacity of bioplastics. However, this class of material suffers from poor mechanical strength in comparison of neat PBAT, especially when the TPS content exceeds 30 wt%. Aiming at enhancing the mechanical performance of PBAT/TPS blends while maintaining relatively high TPS content, cellulose nanofibrils (CNFs) was incorporated into the TPS phase using twin screw extrusion. The effects of CNFs content on the microstructure, mechanical properties, melt-rheology and humidity absorption were investigated. An enhancement in the tensile strength and modulus was noted with the inclusion of CNFs, with optimal performance attained at 8 wt% of CNFs. A narrowing in the distribution of the TPS nodules within the PBAT matrix was also observed with the addition of CNFs, which is expected to be on the origin of the main evolution in the mechanical, rheological and humidity observed. Because of the availability of CNFs, biodegradability and facile processability, the ternary PBAT-TPS-CNFs blends might contribute to improve the performance of this class of biodegradable bioplastic.

Antimicrobial dressing of silver sulfadiazine-loaded halloysite/cassava starch-based (bio)nanocomposites

(Bio)nanocomposites have been studied for biomedical applications, including the treatment of wounds. However, wound infection is one of the main problems of wound care management, and the use of wound dressings with antibacterial agents is essential. This work focused on developing and characterizing silver sulfadiazine-loaded halloysite/cassava starch-based (bio)nanocomposites potentially suitable as antimicrobial dressing. Silver sulfadiazine was complexed inside the halloysite nanotubes lumen, and the drug-loaded nanotubes were incorporated in thermoplastic starch dispersion, forming the (bio)nanocomposites. The silver sulfadiazine-loaded halloysite and the (bio)nanocomposite were characterized by zeta potential, scanning electron microscopy, X-ray diffraction, and infrared spectroscopy. The dressing properties of (bio)nanocomposites (water vapor permeability and mechanical stability) and their antimicrobial efficacy by Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus were also evaluated. Physicochemical studies suggested the silver sulfadiazine-loaded halloysite complexation (zeta potential of -38.9 mV) and its interactions with the starch forming the nanocomposites. The silver sulfadiazine-loaded halloysite/starch-based (bio)nanocomposites possessed a homogeneous and organized structure. Also, they had mechanical properties to be used as a dressing (13.73 ± 3.09 MPa and 3.17 ± 1.28% of elongation at break), and its permeability (6.18 ± 0.43 (10^-13) g.Pa^-1.s^-1.m^-1) could be able to maintain the environmental moisture at the wound surface. Besides that, the (bio)nanocomposites acted against the studied bacteria, being a potential contact antimicrobial and biodegradable wound dressing. Finally, the developed (bio)nanocomposites are semi-occlusive and good candidates for dry wounds to be widely in vitro and in vivo tested as controlled silver sulfadiazine delivery dressing.

Effect of biodegradable active packaging with zeolites on fresh broccoli florets

Most of the food packaging is mainly petroleum-based, and new forms of food packaging have emerged, such as active, intelligent, and biodegradable packaging to extend the shelf life of fresh vegetables. The aim was to develop a biodegradable active packaging and senescence indicator label for fresh broccoli florets (Brassica oleracea L. var. italica), to increase shelf life and to monitor the decay of the vegetable. The biodegradable active packagings (BAP) were produced by blown extrusion containing zeolite as ethylene scavenger, and their mechanical properties, water vapor permeability, and water sorption isotherms were determined. Fresh broccoli florets were packed in perforated and non-perforated BAP and stored at 12 °C, and their weight loss, vitamin C content, color, and texture were evaluated during the storage. BAPs were efficient in reducing the metabolism of fresh broccoli florets stored at 12 °C, preserving the color, and vitamin C content for 7 days. The senescence indicator labels were able to detect CO₂ in packages without perforations.

Ordered long polyvinyl alcohol fiber-reinforced thermoplastic starch composite having comparable mechanical properties with polyethylene and polypropylene

A novel strategy is proposed to fabricate ordered long polyvinyl alcohol fiber (PVAF)-reinforced thermoplastic starch (TPS) composites with significantly improved mechanical properties. The PVAFs were uniformly fixed on two rods first; then sandwich-like TPS/fibers/TPS composite films were prepared by hot pressing, and PVAFs (0-4.08 wt%) with the same orientation were added to the composite films. The tensile test demonstrated that the tensile strength of the PVAF/TPS composite film improved from 2.13 MPa for TPS to 20.98 MPa with 4.08 wt% PVAFs, which is higher than the tensile strength of polyethylene (PE) (11.88 MPa) and polypropylene (PP) (19.29 MPa) and ten times higher than that of TPS. The sandwich-like cross-section of the composite film was observed by scanning electron microscopy to prove the better compatibility between PVAF and TPS. The nanoindentation test revealed that the addition of fibers improved the elastic modulus and hardness of the surface of the material. The strengthening mechanism for different PVAF contents was simulated by finite element analysis and attributed to the reduced maximum von Mises stress at the interface between the fiber and the TPS matrix, avoiding the stress concentration and corresponding fracture. This study provides a new way to prepare degradable composite films with suitable mechanical properties to replace PE or PP.

Improving Thermal Conductivity Coefficient in Oriented Strand Lumber (OSL) Using Sepiolite

An issue in engineered wood products, like oriented strand lumber (OSL), is the low thermal conductivity coefficient of raw material, preventing the fast transfer of heat into the core of composite mats. The aim of this paper is to investigate the effect of sepiolite at nanoscale with aspect ratio of 1:15, in mixture with urea-formaldehyde resin (UF), and its effect on thermal conductivity coefficient of the final panel. Sepiolite was mixed with UF resin for 20 min prior to being sprayed onto wood strips in a rotary drum. Ten percent of sepiolite was mixed with the resin, based on the dry weight of UF resin. OSL panels with two resin contents, namely 8% and 10%, were manufactured. Temperature was measured at the core section of the mat at 5-second intervals, using a digital thermometer. The thermal conductivity coefficient of OSL specimens was calculated based on Fourier’s Law for heat conduction. With regard to the fact that an improved thermal conductivity would ultimately be translated into a more effective polymerization of the resin, hardness of the panel was measured, at different depths of penetration of the Janka ball, to find out how the improved conductivity affected the hardness of the produced composite panels. The measurement of core temperature in OSL panels revealed that sepiolite-treated panels with 10% resin content had a higher core temperature in comparison to the ones containing 8% resin. Furthermore, it was revealed that the addition of sepiolite increased thermal conductivity in OSL panels made with 8% and 10% resin contents, by 36% and 40%, respectively. The addition of sepiolite significantly increased hardness values in all penetration depths. Hardness increased as sepiolite content increased. Considering the fact that the amount of sepiolite content was very low, and therefore it could not physically impact hardness increase, the significant increase in hardness values was attributed to the improvement in the thermal conductivity of panels and subsequent, more complete, curing of resin.

Araucaria angustifolia (Bertol.) Kuntze extract as a source of phenolic compounds in TPS/PBAT active films

There is growing interest in the development of biodegradable packaging materials containing natural antioxidant extracts.

High-Throughput Fabrication Method for Producing a Silver-Nanoparticles-Doped Nanoclay Polymer Composite with Novel Synergistic Antibacterial Effects at the Material Interface

In this study, we report a high-throughput fabrication method at industrial pilot scale to produce a silver-nanoparticles-doped nanoclay-polylactic acid composite with a novel synergistic antibacterial effect. The obtained nanocomposite has a significantly lower affinity for bacterial adhesion, allowing the loading amount of silver nanoparticles to be tremendously reduced while maintaining satisfactory antibacterial efficacy at the material interface. This is a great advantage for many antibacterial applications in which cost is a consideration. Furthermore, unlike previously reported methods that require additional chemical reduction processes to produce the silver-nanoparticles-doped nanoclay, an in situ preparation method was developed in which silver nanoparticles were created simultaneously during the composite fabrication process by thermal reduction. This is the first report to show that altered material surface submicron structures created with the loading of nanoclay enables the creation of a nanocomposite with significantly lower affinity for bacterial adhesion. This study provides a promising scalable approach to produce antibacterial polymeric products with minimal changes to industry standard equipment, fabrication processes, or raw material input cost.