Characterization of waxes as possible coating material for organic aerogels

Conjugated Microporous Polymer Aerogels Encapsulated within Hydroxyapatite Nanowires Exhibit Good Thermal Insulation and Flame-Retardant Properties

Aerogels have been widely studied in the field of thermal insulation. Herein, we reported a kind of conjugated micropolymer (CMP) aerogel synthesized by 1,3,5-triethynylbenzene and 2-amino-3,5-dibromopyridine. To enhance the flame-retardant property, we composited hydroxyapatite (HAP) nanowires with a CMP aerogel. Transmission electron microscopy (TEM) analysis revealed that HAP nanowires were encapsulated within nanosized CMP tubes. In addition, the thermal conductivity of HAP2-NCMP aerogel was 0.0251 W m-1 K-1, which possesses good thermal insulation property. In the micro-combustion calorimeter (MCC) test, compared with pure NCMP, the peak heat release rate (pHRR) of HAP2-NCMP decreased from 39.3 to 30.82 W g-1, approximately 21.6% lower. Furthermore, with the increased addition of hydroxyapatite in the HAP-NCMP composite, the pHRR of HAP3-NCMP decreased by about 37.4%. Besides, NCMP possesses good mechanical properties, with a compressive strength of 117.3 kPa at a strain level of 60%. These findings suggest promising application potential for HAP-NCMP in energy-saving and flame-retardant applications.

Implantable, Bioresorbable Radio Frequency Resonant Circuits for Magnetic Resonance Imaging

Magnetic resonance imaging (MRI) is widely used in clinical care and medical research. The signal-to-noise ratio (SNR) in the measurement affects parameters that determine the diagnostic value of the image, such as the spatial resolution, contrast, and scan time. Surgically implanted radiofrequency coils can increase SNR of subsequent MRI studies of adjacent tissues. The resulting benefits in SNR are, however, balanced by significant risks associated with surgically removing these coils or with leaving them in place permanently. As an alternative, here the authors report classes of implantable inductor-capacitor circuits made entirely of bioresorbable organic and inorganic materials. Engineering choices for the designs of an inductor and a capacitor provide the ability to select the resonant frequency of the devices to meet MRI specifications (e.g., 200 MHz at 4.7 T MRI). Such devices enhance the SNR and improve the associated imaging capabilities. These simple, small bioelectronic systems function over clinically relevant time frames (up to 1 month) at physiological conditions and then disappear completely by natural mechanisms of bioresorption, thereby eliminating the need for surgical extraction. Imaging demonstrations in a nerve phantom and a human cadaver suggest that this technology has broad potential for post-surgical monitoring/evaluation of recovery processes.

Lipid incorporated biopolymer based edible films and coatings in food packaging: A review

In the evolving landscape of food packaging, lipid-based edible films and coatings are emerging as a sustainable and effective solution for enhancing food quality and prolonging shelf life. This critical review aims to offer a comprehensive overview of the functional properties, roles, and fabrication techniques associated with lipid-based materials in food packaging. It explores the unique advantages of lipids, including waxes, resins, and fatty acids, in providing effective water vapor, gas, and microbial barriers. When integrated with other biopolymers, such as proteins and polysaccharides, lipid-based composite films demonstrate superior thermal, mechanical, and barrier properties. The review also covers the application of these innovative coatings in preserving a wide range of fruits and vegetables, highlighting their role in reducing moisture loss, controlling respiration rates, and maintaining firmness. Furthermore, the safety aspects of lipid-based coatings are discussed to address consumer and regulatory concerns.

Enhancement of a hybrid colorimetric film incorporating Origanum compactum essential oil as antibacterial and monitor chicken breast and shrimp freshness

Recently, intelligent packaging has combined several functions, including monitoring and preserving food freshness in real-time. This study was developed a hybrid film (active/ colorimetric) based on AM/CPC/9%SFW as a carrier of Origanum compactum essential oil (OC) in various concentrations (0%, 1%, 1.25%, and 1.5% v/v). The film's emulsions showed homogeneity regarding particle size, polydispersity index, and ζ -potential. Hybrid films' morphological, mechanical, water and light barrier, thermal, and antioxidant properties were enhanced with an increased OC. Interestingly, all films rapidly responded to pH/NH3 and reflected different colors. In the hybrid films, an inhibition effect against gram-positive (Staphylococcus aureus) and gram-negative (Escherichia coli) bacteria and OC (1.5%) film exhibited a large inhibition zone attained diameters of 37.33 and 15.67 mm, respectively, in the disc diffusion test. Outstanding, AM/CPC/9%SFW/1.5 %OC film displayed the ability to preserve and monitor chicken breast and shrimp freshness to 33 and 21 h, respectively, during storage at 25 °C.

Fluidized Bed Spray Coating for Improved Mechanical Properties of Particles

When designing crash absorber particles for application as a filling material in the double-hull of ships, the main goal is to achieve an optimal mechanical performance, in combination with a low-density particle structure, while fulfilling several additional requirements regarding, for example, non-toxic and hydrophobic behavior. In this study, a fluidized bed was used to coat Poraver® glass particles with Candelilla wax and silicone to attain these specifications. A uniform coating was achieved with wax, but the process turned out to be far more challenging when using silicone. To evaluate the suitability of coated particles as a granular filling material, and to compare their performances with that of untreated Poraver® particles, several mechanical tests, as well as structural investigations, were conducted. While no notable improvement in mechanical behavior was observed on the single-particle level, bulk tests showed promising results regarding compressibility and abrasion resistance of coated particles compared to untreated ones.

Biodegradable active packaging: Components, preparation, and applications in the preservation of postharvest perishable fruits and vegetables

The consumption of fresh fruits and vegetables is restricted by the susceptibility of fresh produce to deterioration caused by postharvest physiological and metabolic activities. Developing efficient preservation strategies is thus among the most important scientific issues to be urgently addressed in the field of food science. The incorporation of active agents into a polymer matrix to prepare biodegradable active packaging is being increasingly explored to mitigate the postharvest spoilage of fruits and vegetables during storage. This paper reviews the composition of biodegradable polymers and the methods used to prepare biodegradable active packaging. In addition, the interactions between bioactive ingredients and biodegradable polymers that can lead to plasticizing or cross-linking effects are summarized. Furthermore, the applications of biodegradable active (i.e., antibacterial, antioxidant, ethylene removing, barrier, and modified atmosphere) packaging in the preservation of fruits and vegetables are illustrated. These films may increase sensory acceptability, improve quality, and prolong the shelf life of postharvest products. Finally, the challenges and trends of biodegradable active packaging in the preservation of fruits and vegetables are discussed. This review aims to provide new ideas and insights for developing novel biodegradable active packaging materials and their practical application in the preservation of postharvest fruits and vegetables.

Effect of sugarcane bagasse on thermal and mechanical properties of thermoplastic cassava starch/beeswax composites

The demand for biodegradable material has been an important issue, especially in food packaging applications. Among many biodegradable materials, starch biopolymer has been recognised as a completely biodegradable material that can be produced from various plants. It is one of the richest resources that are renewable, biodegradable, and available at low cost. However, starch biopolymers are often associated with poor mechanical properties. Hence, the main objective of this study is to evaluate the mechanical and thermal characteristics of sugarcane bagasse fibre (SBF) reinforced thermoplastic cassava starch (TPCS), which was prior modified with beeswax (BW). It was found that the mechanical properties such as tensile, flexural, and impact strength have improved significantly with the incorporation of SBF loading into the TPCS/BW matrix. The highest tensile strength (12.2 MPa) and modulus (2222.6 MPa) were exhibit by sample with 20 wt% SBF loading and further increment of fibre led to decrease in the strength of the materials. The thermal properties showed that higher SBF loading resulted in improved thermal stability of the material, i.e., higher glass transition and melting temperature than the polymer matrix. Overall, SBF has shown good potential as a reinforcing material which is able to improve the functional characteristics of TPCS/BW as a new potential biodegradable material.

A Novel Multilayer Natural Coating for Fed-State Gastric Protection

Several nutraceutical products require gastric protection against the hostile environment in the stomach. Currently marketed synthetic and semi-synthetic coatings suffer from major shortcomings such as poor gastric protection, slow-release response to pH change, and the use of artificial ingredients. The challenge of coating natural products is further exacerbated by the relatively high gastric pH in the fed state. In this work, a novel natural enteric coating is presented as a breakthrough alternative to current solutions. Two coating systems were devised: (i) a triple-layer coating that comprises a wax layer embedded between two alginate-based coatings, and (ii) a double-layer coating, where an overcoat of organic acids (fumaric or citric acid) is applied to an alginate-based coating. The multi-layer architecture did not impact the pH-responsive nature of the coating even when more biologically relevant Krebs bicarbonate buffer of lower buffer capacity was used. Interestingly, the gastric protection barrier of organic acid-based coating remained resistant at elevated gastric pH 2, 3, or 4 for 2 h. This is the first report of using an alginate-based coating to provide gastric protection against fed-state stomach conditions (pH 2–4). Being biodegradable, naturally occurring, and with no limit on daily intake, the reported novel coating provides a superior platform to current coating solutions for pharmaceutical and nutraceutical products.

Thermoplastic starch/beeswax blend: Characterization on thermal mechanical and moisture absorption properties

Cassava starch has acquired many attentions owing to its ability to be developed as thermoplastic cassava starch (TPCS) where it can be obtained in low cost, making it to be one of alternatives to substitute petroleum-based plastic. An attempt was made to investigate the thermal, mechanical and moisture absorption properties of thermoplastic cassava starch blending with beeswax (TPCS-BW) fabricated using hot moulding compression method in the range of beeswax loading from 0, 2.5, 5 to 10 wt%. Addition of beeswax has significantly reduced tensile strength, elongation and flexural strength while improving tensile modulus and flexural modulus until 5 wt% beeswax. Incorporation of 10 wt% beeswax has successfully produced the lowest value of moisture absorption and water solubility among the bio-composite which might be attributed to the beeswax's hydrophobic properties in improving water barrier of the TPCS-BW bio-composite. Furthermore, the addition of beeswax resulted in the appearance of irregular and rough fractured surface. Meanwhile, fourier transform infrared (FT-IR) spectroscopy presented that incorporation of beeswax in the mixture has considerably improve hydrogen bonding of blends indicating good interaction between starch and beeswax. Hence, beeswax with an appropriate loading value able to improve the functional properties of TPCS-BW bio-composite.

Potentials of polysaccharides, lipids and proteins in biodegradable food packaging applications

Bio-based packaging materials are gaining importance due to their biodegradability, sustainability and environmental friendliness. To control the food quality and improve the food safety standards, proteins polysaccharide and lipid-based packaging films are enriched with bioactive and functional substances. However, poor permeability and mechanical characteristics are the challenging areas in their commercialization. Scientists and researchers are using a combination of techniques i.e. hydrogels, crosslinking, etc. to improve the intermolecular forces between different components of the film formulation to counter these challenges More recently, biodegradable packaging materials, sometimes edible, are also used for the delivery of functional ingredients which reveals their potential for drug delivery to counter the nutrient deficiency problems. This study highlights the potentials of bio-based materials i.e. proteins, polysaccharides, lipids, etc. to develop biodegradable packaging materials. It also explores the additives used to improve the physicochemical and mechanical properties of biodegradable packaging materials. Furthermore, it highlights the novel trends in biodegradable packaging from a food safety and quality point of view.

Accelerated Ageing Procedures to Assess the Stability of an Unconventional Acrylic-Wax Polymeric Emulsion for Contemporary Art

This research evaluates the stability of an aqueous emulsion of acrylic copolymers and waxes. Edelwachs, generally applied on wood, has been recently used as an unconventional medium in contemporary painting. Through Pyrolysis-Gas Chromatography-Mass Spectrometry (Py-GC-MS) and Fourier Transformed Infrared Attenuated Total Reflectance (FT-IR-ATR) analyses, the composition of Edelwachs was defined as a mixture of acrylic polymers (MA, MMA, nBA, nBMA), Carnauba and microcrystalline waxes and additives. Mock-ups-obtained mixing Edelwachs with titanium white, zinc white and ultramarine blue were subjected to UV, high temperatures, and high relative humidity accelerated ageing. The effect of the ageing procedures was evaluated through optical microscopy, colourimetric measurements, FT-IR-ATR, Thermogravimetry and Differential Scanning Calorimetry (TG-DSC) and wettability measures. FT-IR-ATR spectra do not show significant variations in terms of chemical stability, indicating a fair stability of Edelwachs as a painting binder. UV and high temperature treatments show the most relevant effects in terms of colorimetric changes (increasing of b*) and thermal stability. The TG-DSC highlights the influence of the pigments (specifically zinc white) mainly on the thermal behaviour of the acrylates. The unexpected decrease of wettability of the paint films, registered after ageing, may indicate a possible phase separation among acrylates and waxes.