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This review article provides a thorough overview of barrier coating materials that have been used in food packaging with a focus on biodegradable (bio-based or petroleum-based) materials, such as lipids, proteins, polysaccharides, agriculture waste and polyesters. The goal is to provide an opportunity to acknowledge progress made in this field, focusing on modifications made to coatings. These modifications aim to address the shortcomings of biodegradable substrates (either plastic or paper) and improve their performance, enabling them to compete with traditional petroleum-based food packaging materials. This includes their barrier against water vapor and oxygen, mechanical and surface characteristics (sealability and adhesion), as well as antimicrobial properties. The barrier of most biodegradable polymers underperforms in comparison with petroleum-based non-biodegradable polymers, which possess either high water vapor barrier or high oxygen barrier. Coating technology is a promising solution particularly in barrier improvement of biodegradable polymers. Currently, there are only metallized, or inorganic nanosheet coatings available for biodegradable films that meet food packaging requirements. There are some challenges in this field, for example, being able to retain the coating's biodegradability despite applied modifications to improve it's performance, the large-scale fabrication of biodegradable coatings, the coating's delamination and heat-sealability during service time, and the migration of the coating into the packaged food. Moreover, green chemistry and its sustainability needs in biodegradable polymeric coatings are also discussed regarding new ideas and possible directions for widespread application of coatings in food packaging. This is the first review that specifically summarizes biodegradable coatings on plastic and paper substrates with a focus on coating modifications to improve the performance of the base substrate to meet the required properties for food packaging applications. [ABSTRACT FROM AUTHOR]

This paper introduces a novel data‐driven approach to develop a fault‐tolerant model predictive controller (MPC) for non‐linear systems. By adopting a Koopman operator‐theoretic perspective, the proposed method leverages historical data from the system to construct a data‐driven model that captures the non‐linear behaviour and fault characteristics. The fault influence is addressed through an online estimation of a time‐varying Koopman predictor, which allows for adjusting the MPC control law to counteract the fault effects. This estimation is performed in a higher dimensional Koopman feature space, where the dynamics behave linearly. As a result, the non‐linear fault‐tolerant MPC optimization problem can be replaced with a more practical and feasible linear time‐varying one using the approximated Koopman predictor. Moreover, by incorporating the online update procedure, the time‐varying Koopman predictor can represent the dynamics of the faulty system. Hence, the controller can adapt and compensate for the faults in real‐time, integrating the fault diagnosis module in the MPC framework and eliminating the need for a separate fault detection unit. Finally, the efficacy of the proposed approach is demonstrated through case study results, which highlight the ability of the controller to mitigate faults and maintain desired system behaviour. [ABSTRACT FROM AUTHOR]

This paper presents a novel method for output redefinition for linear systems. The approach also determines possible relative degrees for the systems corresponding to any new output vector. To guarantee the minimum phase property with a prescribed relative degree, a set of new conditions is introduced. A key feature of these conditions is that there is no need to any form of transformations which make the scheme suitable for optimisation problems in control to ensure the minimum phase property. Moreover, the results are useful for sensor placement problems and for obtaining minimum phase approximations of non-minimum phase systems. Numerical examples including an example of unmanned aerial vehicle systems are given to demonstrate the effectiveness of the methodology. [ABSTRACT FROM AUTHOR]

Recently, there has been immense interest in using biodegradable polymers to replace petro-derived polymers. Poly(3-hydroxybutyrate- co -3-hydroxyvalerate) (PHBV), which is gaining popularity due to its biodegradability, is used in developing blends and composites for a variety of applications. To enhance the miscibility between different components of a material with PHBV, functionalization of the PHBV chain can be done. In this study, grafting of maleic anhydride (MA) onto PHBV was performed using organic peroxide also, called Luperox [2,5-dimethyl-2,5-di( tert -butylperoxy)hexane], as an initiator. The effects of different initiator and MA concentrations on the grafting percentage, gel content, rheology, and thermal properties were evaluated. Additionally, a chain extender (Joncryl ADR 4468) was added during the grafting process to prevent chain scission of PHBV during processing and to promote long-chain branching. Higher initiator concentrations played a significant role in increasing the grafting percentage. Adding the chain extender further enhanced the grafting percentage of the compatibilizers. Compatibilizers with chain extenders increased the grafting percentage by up to 91% compared with their counterparts without chain extenders. Differential scanning calorimetry analysis demonstrated that the melting temperature of the compatibilizers decreased by up to 8 °C with increasing initiator concentration. Furthermore, the thermal stability of maleic anhydride grafted PHBV (MA- g -PHBV) reduced at higher initiator content, likely attributed to the formation of low-molecular-weight species during processing. The maleated PHBV with a chain extender exhibited improved thermal stability, with an increase of up to 6 °C, attributed to an increase in molecular weight because of the chain extender. This can be corroborated by the rheological studies, which showed higher viscosity, particularly for MA- g -PHBV with chain extender. Therefore, this is the first ever scientific study to improve and analyze the grafting percentage of MA- g -PHBV using a combination of chain extender and varying initiator concentrations. This maleated PHBV with a higher grafting percentage will then facilitate the development of composites and blends with improved performance, even at low MA- g -PHBV concentrations., Competing Interests: The authors declare no competing financial interest., (© 2024 The Authors. Published by American Chemical Society.)