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Each year, 50 to 70 million tonnes of lignin are produced worldwide as by-products from pulp industries and biorefineries through numerous processes. Nevertheless, about 98% of lignin is directly burnt to produce steam to generate energy for the pulp mills and only a handful of isolated lignin is used as a raw material for the chemical conversion and for the preparation of various substances as well as modification of lignin into nanomaterials. Thus, thanks to its complex structure, the conversion of lignin to nanolignin, attracting growing attention and generating considerable interest in the scientific community. The objective of this review is to provide a complete understanding and knowledge of the synthesis methods and functionalization of various lignin nanoparticles (LNP). The characterization of LNP such as structural, thermal, molecular weight properties together with macromolecule and quantification assessments are also reviewed. In particular, emerging applications in different areas such as UV barriers, antimicrobials, drug administration, agriculture, anticorrosives, the environment, wood protection, enzymatic immobilization and others were highlighted. In addition, future perspectives and challenges related to the development of LNP are discussed.

Bài báo trình bày kết quả phát triển vật liệu composite mới nguồn gốc tự nhiên trên cơ sở nhựa epoxy resorcinol sinh học – diatomite bằng quy trình xanh hai giai đoạn dựa trên đặc tính “sống” của sự trùng hợp cation. Bao gồm sự khởi đầu phản ứng bằng ánh sáng và sau đó là sự hóa rắn không cần ánh sáng dưới tác dụng nhiệt, quy trình này cho phép thu được các composite epoxy-diatomite dày và không trong suốt mà không cần dùng bất cứ dung môi hay chất hóa rắn gốc amine nguy hại nào. Các ảnh hưởng của hàm lượng diatomite đối với các tính chất cơ học và phản ứng với lửa của những composite này đã được khảo sát. Trên cơ sở đánh giá các tính chất này, composite thu được với diatomite chiếm 40% khối lượng được xem như composite tối ưu. Composite này có mô đun uốn là 3,6 MPa và ứng xử làm chậm cháy đáng chú ý với đỉnh tốc độ tỏa nhiệt (peak of Heat Release Rate - pHRR) 132 W/g và tổng lượng tỏa nhiệt 6 kJ/g ghi nhận được trong phân tích nhiệt lượng kế dòng đốt cháy nhiệt phân (Pyrolysis Combustion Flow Calorimetry - PCFC).

The present study investigated the flame-retardant (FR) effect of transparent epoxy coating containing aluminum hypophosphite (AHP) nanoparticles (NPs) on polylactic acid (PLA) sheets used as a typical model of combustible polymeric material. First, AHP NPs (≤60 nm) were prepared by a specific two-stage wet milling process and deeply analyzed (morphology, thermal/mechanisms of degradation under nitrogen and air). The thermal properties of epoxy–AHP nanocomposites were compared with the pristine epoxy resin. The addition of AHP NPs into epoxy resin accelerated thermal degradation of the coating, thereby increasing the amount of char residue. The application of blank epoxy coating on the surface of PLA plate slightly made PLA more ignitable, without any reduction in the peak of heat release rate (pHRR). The decrease of time to ignition (TTI) was more important in the presence of AHP NPs due to their reactivity toward epoxy resin. Epoxy coating containing 15 wt.% AHP NPs showed the most significant reduction in pHRR as the result of the formation of a homogenous char layer. Further increase of AHP NPs content up to 20 wt.% did not end in any further enhancement, as a consequence of structural cracks observed in the coating that prevent the formation of an effective char. The coated samples remained transparent, promisingly paving the way to appropriate decorative flame-retardant coatings.

The surge towards a sustainable future in the construction industry requires the use of bio-based insulation materials as an alternative to conventional ones for improving energy efficiency in structures. In this article, the features of bio-based insulation materials, including their thermal conductivities, moisture buffering value, fire performance, and life cycle evaluations are examined. It is clear from the review that pre- and post-treatment of the bio-based materials used for insulation materials optimize their properties. The life cycle analysis reveals a significant reduction in global warming potential (GWP) compared to conventional foams. In addition, it is envisaged that producing bio-based insulation materials on a larger scale will further decrease the net GWP. The article, therefore, proposes the implementation of policies that will promote the commercialization of bio-based insulation materials. Licens fulltext: CC BY License

In this work, a green synthesis method was designed and practiced to develop bioactive and biocompatible carbon-based nanocomposites biomaterials. ZnO nanoparticles were synthesized in assistance of leaf extracts and added to a composite nanostructure composed of the reduced graphene oxide (rGO) and multi-walled carbon nanotubes (MWCNT). The resulting green nanocomposite revealed ability to make π-π interactions, hydrogen bonding, and van der Waals interactions with the doxorubicin (DOX). Then, the surface morphology of the synthesized nanocomposite was investigated, and the interrelationship between the surface morphology, relative cell viability, and drug uptake and release behavior were discussed. This phenomenon was conceptualized to optimize the interactions between the biomolecules and the substrate by reaching significant drug payload and cellular internalizations. The results suggest that the drug-nanocomposite interactions (hydrogen bonding, van der Waals, n → σ* interactions) are of prime importance which determine the ability of the developed nanocomposite to drug uptake. The porosity, encapsulation, and trapping the drug via only physical and spatial entrapment techniques are also important.

International audience

Lignin-containing micro/nano fibrillated cellulose (L-MNFCs) and phosphorylated L-MNFCs were produced from beechwood sawdust by combining steam explosion (SE) pretreatment, a bleaching step, a phosphorylation reaction using urea and etidronic acid, and an ultra-fine grinding. The contents of phosphorus and nitrogen on the cellulose surface were obtained by elemental analysis (P ≈ 2.7% and N ≈ 1.2% respectively). The chemical composition of the pulps was assessed by ionic chromatography (HPAEC PAD) and the morphology of phosphorylated (L-)NMFCs were analyzed by Morfi Neo. The successful grafting of phosphate groups was verified by FTIR, 13C CPMAS, 31P NMR. Thermal and fire behaviors were examined by TG/DTG analysis and pyrolysis combustion flow calorimetry (PCFC). It was found that SE pretreatment itself can significantly improve the thermal degradability and fire resistance of L-MNFCs. Phosphorylated (lignocellulosic) micro/nano fibrillated cellulose exhibiting a remarkable elevation in their thermal degradation and flame-retardancy have been produced.

In 2019, we introduced Flame Retardancy Index (FRI) as a universal dimensionless index for the classification of flame-retardant polymer materials (Polymers, 2019, 11(3), 407). FRI simply takes the peak of Heat Release Rate (pHRR), Total Heat Release (THR), and Time-To-Ignition (ti) from cone calorimetry data and quantifies the flame retardancy performance of polymer composites with respect to the blank polymer (the reference sample) on a logarithmic scale, as of Poor (FRI ˂ 100), Good (100 ≤ FRI ˂ 101), or Excellent (FRI ≥ 101). Although initially applied to categorize thermoplastic composites, the versatility of FRI was later verified upon analyzing several sets of data collected from investigations/reports on thermoset composites. Over four years from the time FRI was introduced, we have adequate proof of FRI reliability for polymer materials ranking in terms of flame retardancy performance. Since the mission of FRI was to roughly classify flame-retardant polymer materials, its simplicity of usage and fast performance quantification were highly valued. Herein, we answered the question “does inclusion of additional cone calorimetry parameters, e.g., the time to pHRR (tp), affect the predictability of FRI?”. In this regard, we defined new variants to evaluate classification capability and variation interval of FRI. We also defined the Flammability Index (FI) based on Pyrolysis Combustion Flow Calorimetry (PCFC) data to invite specialists for analysis of the relationship between the FRI and FI, which may deepen our understanding of the flame retardancy mechanisms of the condensed and gas phases.

The increased use of plastics, particularly in terms of the use of polymers in electronics and electrical devices commonly used in homes, offices, schools, restaurants, and vehicles, has caused increased fire risks [...]

International audience; Poly(3-hydroxybutyrate), PHB, has gathered a lot of attention for its promising properties—in particular its biobased nature and high biodegradability. Although PHB is prime candidate for the packaging industry, the applications are still limited by a narrow processing window and thermal degradation during melt processing. In this work, three novel additives based on ferulic acid esterified with butanediol, pentanediol, and glycerol (BDF, PDF, and GTF, respectively) were used as plasticizers and antioxidative additives to improve mechanical properties of PHB. Elongation at break up to 270% was obtained in presence of BDF and the processing window was improved nearly 10-fold. The Pawley method was used to identify the monoclinic space group P2 of the BDF. The estimated crystallite size (71 nm) agrees with a crystalline additive. With PHB70BDF30 blends, even higher elongations at break were obtained though dwindled with time. However, these properties could be recovered after thermal treatment. The high thermal stability of this additive leads to an increase in the fire retardancy property of the material, and the phenolic structure induced antioxidant properties to the samples as demonstrated by radical scavenging tests, further highlighting the possibilities of the PHB/additive blends for packaging applications.

Synthesis of fully eco-friendly thermosets based on renewable resorcinol diglycidyl ether (RE) hardenered with different biobased diamines having aliphatic, cyclic, or aromatic backbones were prepa...

Designing novel biomaterials for tissue engineering purpose is an obvious necessary considering ever increasing need for appropriate biocompatibility and properties to achieve the maximum regeneration. In this research, a new type of biomaterial based on poly (phenylene sulfide) (PPS) and reduced graphene oxide (rGO) was synthesized and applied within chitosan based hydrogel to evaluate its performance as a wound dressing potentially. Fourier transform infrared spectroscopy (FTIR), X-ray diffraction spectrometry (XRD), scanning electron microscopy (SEM) and compression tests were performed to assess suitability of composite biomaterial. Thermal behavior of the PPS/rGO composite was evaluated by differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA). The PPS/rGO composition of 90: 10 (w/w) was selected because of having the highest biocompatibility and utilized in chitosan hydrogel. Chitosan hydrogel swelling ratio was declined from 800 to 200% by PPS/rGO addition; likewise, water vapor transition rate (WVTR) was dropped. A proper biocompatibility and cell attachment was confirmed, where porosity of ca. 80% appeared promising for tissue engineering uses. Overall, the result confirmed the appropriateness of PPS/rGO for tissue engineering uses.

In this work, GTR/thermoplastics blends (in ratio 50/50 and 75/25 wt.%) were prepared by melt-compounding in an internal mixer. During research, trans-polyoctenamer rubber (TOR), ethylene-vinyl acetate copolymer (EVA), ethylene-octene copolymer (EOC), and linear low-density polyethylene (LLDPE), were used in their thermoplastic phase. Microstructure and processing-performance property interrelationships of the studied materials were investigated by: atomic force microscopy (AFM), scanning electron microscopy (SEM), rubber process analyzer (RPA), Mooney viscometer, plastometer, gas chromatography with mass spectrometry, differential scanning calorimetry (DSC), tensile tests and swelling behavior. In blends of thermoplastics with a high content of GTR (50 and 75 wt.%), the thermoplastic modifier type had a significant impact on the processing behavior and microstructure of blends. In terms of the physico-mechanical properties, the GTR/thermoplastics ratio affected elongation at break, hardness, and density, while its effect on tensile strength was negligible. DSC analysis showed that thermoplastics, as modifiers of GTR, should be considered as binders and not plasticizers, as reflected in the almost constant glass-transition temperature of the blends. RPA measurements indicated higher values of G* and η* for GTR-rich blends. SEM showed a rubber-like interfacial break, while AFM confirmed interfacial contact between GTR and thermoplastics. Financial support of these studies from Gdańsk University of Technology by the DEC-1/2020/IDUB/II.1.3 grant under the Aurum Supporting International Research Team Building program—‘Excellence Initiative-Research University’ is gratefully acknowledged.

The development of biodegradable and compostable materials as alternative to fossil-based plastics is to-day of paramount importance. Polybutylene succinate (PBS) is a class of biodegradable aliphatic polyester that can be achieved from succinic acid and 1,4 butanediol, which is of broad scientific and industrial inter -est among other biodegradable polyesters due to its compostability according to ISO EN13432 standard. PBS is considered one of the most interesting compostable polymers because of the good compromise of mechanical endurance, ductility, toughness and impact resistance. It is also characterized by a remarkable thermal resistance with heat deflection temperature (HDT) of over 90 degrees C. Nevertheless, due to its limited Young's modulus as well as its susceptibility to sudden degradation during melt processing, especially at high temperature, PBS is often blended and reinforced with other polymers, fillers and additives to tackle the issues of better processability, higher stiffness, and improved overall mechanical strength. Most common blends of PBS include poly(lactic acid) (PLA), another widespread compostable (and biobased) polyester, which is often added, in different proportion to PBS, to achieve tailored thermo-mechanical response behavior. Other additives and compatibilizers are also frequently used in PBS blends to achieve a wider processing window with better thermal resistance and better mechanical performance thanks to its customizable composition. Thus, recent advances in polymer blending processes have rendered PBS blends an interesting material platform for applications that require a balance of mechanical strength and flexibility as well as thermal resistance together with compliance to industrial compostability standards. This manuscript reviews briefly the synthesis routes of PBS together with the main thermo-mechanical and physical properties as well as recent progress in developing PBS-based blends for industrial applica-tions. The challenges and future perspectives for the employment of PBS blends in every-day applications are also considered.(c) 2022 Elsevier B.V. All rights reserved.

The biodegradability and mechanical properties of polysaccharides are dependent on their architecture (linear or branched) as well as their crystallinity (size of crystals and crystallinity percent). The amount of crystalline zones in the polysaccharide significantly governs their ultimate properties and applications (from packaging to biomedicine). Although synthesis, characterization, and properties of polysaccharides have been the subject of several review papers, the effects of crystallization kinetics and crystalline domains on the properties and application have not been comprehensively addressed. This review places focus on different aspects of crystallization of polysaccharides as well as applications of crystalline polysaccharides. Crystallization of cellulose, chitin, chitosan, and starch, as the main members of this family, were discussed. Then, application of the aforementioned crystalline polysaccharides and nano-polysaccharides as well as their physical and chemical interactions were overviewed. This review attempts to provide a complete picture of crystallization-property relationship in polysaccharides.

International audience; Development of green flame retardants has become a core part of the attention of material scientists and technologists in a paradigm shift from general purpose to specific sustainable products. This work is the first report on the use of coffee biowastes as sustainable flame retardants for epoxy, as a typical highly flammable polymer. We used spent coffee grounds (SCG) as well as SCG chemically modified with phosphorus (P-SCG) to develop a sustainable highly efficient flame retardant. A considerable reduction in the peak of heat release rate (pHRR) by 40% was observed in the pyrolysis combustion flow calorimeter analysis (PCFC), which proved the merit of the used coffee biowastes for being used as sustainable flame retardants for polymers. This work would open new opportunities to investigate the impact of other sorts of coffee wastes rather than SCG from different sectors of the coffee industry on polymers of different family.

Additive manufacturing has attracted much attention in the last decade as a principal growing sector of complex manufacturing. Precise layer-by-layer patterning of materials gives rise to novel designs and fabrication strategies that were previously not possible to realize with conventional techniques. Using suitable materials and organized variation in the printing settings, parts with time-dependent shapes that can be tuned through environmental stimuli can be realized. Given that these parts can either change their shape over time to a pre-programmed three-dimensional shape or revert to an initial design, this process has become referred to as four-dimensional (4D) printing. In this regard, the commonly-used polylactic acid (PLA) polymer has been recognized as a compelling material candidate for 4D printing as it is a biobased polymer with great shape memory behavior that can be employed in the design and manufacturing of a broad range of smart products. In this review, we investigate the material properties and shape memory behavior of PLA polymer in the first section. Then, we discuss the potential of PLA for 4D printing, including the principles underlying the strategy for PLA-based printing of self-folding structures. The resulting materials exhibit response to environmental stimulus as well as temperature, magnetic field, or light. We additionally discuss the impact of geometrical design and printing conditions on the functionality of the final printed products.

Natural and biodegradable polymers are of particular interest as green sources with low-cost and environmentally friendly features, and have been widely used for polymer composite development. The term “Green Composites” refers to polymer/filler systems in which polymer, filler, or sometimes both components are green in view of sources from which they are yielded or their biodegradability. Natural fibers obtained from plants, animals, and/or geological processes are a big class of green sources widely applied in green composite development. There has also been continued research on recycling of green composite as well as developing hybrid systems for advanced applications. In view of their outstanding biodegradability and biocompatibility in biological media, green composites are crucial elements in medicine. For instance, chitin, chitosan, alginate, and collagen are green polymers widely used for manufacturing composites for hard tissue repair. Several green composite polymers have been used for development of hard tissue implants such as artificial bone, bone cement, knee hip replacement, and spine instrumentation. This review attempts to classify and discuss applications of green composites in bone tissue engineering. Applications of different types of natural fiber biocomposite scaffolds for fractured bone repair were reviewed; besides, morphological structures of scaffolds were correlated with the mechanical properties of human bone.

International audience

International audience

Nowadays, roughly 90% of worldwide epoxy resin materials are made from diglycidyl ether of bisphenol A (DGEBA). This resin offers unique features such as outstanding mechanical properties, chemical resistance, and shape stability. By contrast, the growing awareness of environmental issues, global warming, and depletion of petroleum reservoir suggest search for using bio-epoxy resin from sustainable resources. Indeed, DGEBA is a petroleum-based monomer obtained from bisphenol A and epichlorohydrin, two potential precursors harmful for the environment and human health as well. The problem deepens when it comes to the high flammability of such materials, which restricts their use in strategic applications. Although the introduction of flame retardant (FR) additives to epoxy matrices has been a major strategy to induce flame retardancy, negative impact on mechanical properties and migration of FRs to the materials’ surface remained unresolved issues. Tailoring epoxy chains with chemically bonded reactive flame retardants to epoxy resins would be the solution to avoid migration of FRs to surface, along with protecting mechanical properties of resin. With the rapid development of reactive bio-based FRs and epoxy resins, production of flame retardant bio-epoxy with high biomass content has become a promising strategy to address these issues. This conside review encompasses latest progress in flame retardant bio-epoxy resins made of different resources, with inherent chemical structures of either epoxy monomers or embedded reactive flame retardant elements.

From sustainability standpoint, bio-based resins are of crucial importance nowadays rather than fossil-based resins, but the former suffers from low flame retardancy. Bio-based thin films and coatings are in their early stage of development; hence, a long way must be paved to make them resistant against flame/fire. Polylactic acid (PLA)-based biocompatible (timesand some biodegradable) coatings have been in the core of attention, but even among available works one can rarely find a comprehensive report on flame retardancy of PLA thin films and coatings. Attention should also be paid to the fact that first-generation biodegradable polyesters, PLAs, are not fully biodegradable. Moreover, synthesis of PLAs is hooked on crop consumption. On the other hand, polyhydroxyalkanoates (PHAs) with more or less similar structure, but different physical properties due to their lower glass transition temperature compared with PLAs, are known as the second-generation of bio-polyester. Overall, we highlight here that PHAs might be a better candidate for thin film manufacturing thanks to their synthesis by microorganism as well as significant variability of their microstructure that provides a wide range of properties, and notably their full biodegradability compared with PLAs. Though mass production of PHAs is not cost-effective these days and their market just entered into the growth phase, we suggest study on flame retardancy of PHA-based resins, thin films, and coatings for near future. This short communication deals with the current status and future ahead of PHA-based flame retardant thin films and coatings.

The mission of an advanced epoxy-based nanocomposite coating is to provide a given substrate with protection against an unwelcome guest; e.g. corrosive molecules/media, environmental stress, flame, thermal degradation or microorganisms. In such systems, the degree to which superior properties can be guaranteed depends on the state of network formation in the epoxy in the presence of nanoparticles. For low-filled epoxy nanocomposite coatings, barrierity was taken as the main mechanism controlling over the efficiency of corrosion inhibition in the coating against oxygen or other corrosive moieties, whilst in highly-loaded nanocomposites one should take a closer look at both physical and chemical interaction between the resin and nanoparticles. In this sense, epoxy/Fe3O4 systems were studied here as model nanocomposite coatings and their anti-corrosion and flame retardancy potentials were patterned in terms of qualitative cure analysis made in terms of Cure Index. Anti-corrosion and flame retardancy properties of the aforementioned nanocomposite coatings were mechanistically described at either low or high loading levels in view of Cure Index for postulates of structure-properties association in advanced nano-Fe3O4 incorporated epoxy nanocomposite coatings. We hope that speculations and visulizations provided here about structure-properties relationships are useful to be used in open discussions between experts in the hope of generalization to complex systems containing different types of nanoparticles whatever surface functionality.

The necessity of research on flame retardancy has directed attentions toward development of advanced coating systems in order to meet requirements of competitive markets. As a result, a wide range of organic coating materials were developed in the quest of higher flame retardancy performance. Polyaniline (PANI) as a promising conductive polymer has been widely considered for various applications, and it quite frequently took credit for the success. This article deals with the benefits expecting from PANI in advanced flame retardant systems in view of its extraordinary fire retardancy performance. The necessity of study on potentially high thermal stability and flame retardancy of advanced coating systems containing PANI was also discussed. There is a belief that identifying the worth of PANI as the most famous member of conductive polymers may help determine the locus of PANI in an inevitable shift from general-purpose to advanced flame retardant (FR) systems in which PANI plays a dual role. Harmoniously, ongoing progress in the knowledge and technology of FR coating systems would enliven emerging technologies for utilizing organic materials in response to increasing demand for PANI-based systems with an additional flame retardancy mission in the near future.

Silicone elastomer coatings are known for their softness and high elongation properties, but not for faithful service over time because of their inadequate adhesion, thermal, and mechanical properties. Addition of nanofillers to silicone would be the solution to such long-standing shortcomings, but yet there is a little guarantee of success because of silicone crosslinking being significantly hindered by filler incorporation. In this work, well-cured 3D silicone networks are formed by peroxide curing in the presence of pristine and silane-functionalized halloysite nanotubes (HNTs). Nanofillers are incorporated into silicone at different loadings and the curing potential of the resulting nanocomposite coatings are evaluated by dimensionless indexes of T* and ΔH* calculated from nonisothermal differential scanning calorimetry. Regardless of the content and surface chemistry of the HNTs, silicone nanocomposite was outstandingly cured by peroxide thanks to reactive surface of nanofillers. Overall, ΔH* value of ≈ 2 was indicative of a two-fold rise in the amount of heat release in silicone nanocomposites whatever heating rate. Moreover, T* values obtained were slightly lower than 1, a signature of an unhindered curing. The excellence of facilitated crosslinking brought about by the use of HNTs was featured by an improved polymer-filler interaction, which seems promising for coating applications.

Additive manufacturing (AM) is recently imposing as a fast, reliable, and highly flexible solution to process various materials, that range from metals to polymers, to achieve a broad variety of customized end-goods without involving the injection molding process. The employment of biomaterials is of utmost relevance as the environmental footprint of the process and, consequently, of the end-goods is significantly decreased. Additive manufacturing can provide, in particular, an all-in-one platform to fabricate complex-shaped biobased items such as bone implants or biomedical devices, that would be, otherwise, extremely troublesome and costly to achieve. Polyhydroxyalkanoates (PHAs) is an emerging class of biobased and biodegradable polymeric materials achievable by fermentation from bacteria. There are some promising scientific and technical reports on the manufacturing of several commodities in PHAs by additive manufacturing. However, many challenges must still be faced in order to expand further the use of PHAs. In this framework, the present work reviews and classifies the relevant papers focused on the design and development of PHAs for different 3D printing techniques and overviews the most recent applications of this approach.

Fire safety has become a major concern due to the ubiquitous use of polymers. The development of flame retardant polymer materials has consequently experienced a huge growth in market size. New strategies and legislation have also been proposed to save lives and property. The science and economics of flame retardancy, fire regulations, and new technologies are under permanent evolution. This review paper focuses on revisiting and classifying recent developments in the knowledge and technology of flame retardant polymer materials and demonstrating the qualitative and quantitative analyses carried out on their flame retardant properties. In particular, it comprehensively addresses the progress made and the future prospects for designing precise structures via innovative technologies, particularly 3D printing - as the state-of-the-art manufacturing methodology providing innovative features in this realm of research - and their flame retardancy performances. Indeed, the strategies driving the technologies of innovative flame retardant polymer materials and 3D printing technology are approaching a practical juncture in the near future.

This study has developed novel fully bio-based resorcinol epoxy resin&ndash, diatomite composites by a green two-stage process based on the living character of the cationic polymerization. This process comprises the photoinitiation and subsequently the thermal dark curing, enabling the obtaining of thick and non-transparent epoxy-diatomite composites without any solvent and amine-based hardeners. The effects of the diatomite content and the compacting pressure on microstructural, thermal, mechanical, acoustic properties, as well as the flame behavior of such composites have been thoroughly investigated. Towards the development of sound absorbing and flame-retardant construction materials, a compromise among mechanical, acoustic and flame-retardant properties was considered. Consequently, the composite obtained with 50 wt.% diatomite and 3.9 MPa compacting pressure is considered the optimal composite in the present work. Such composite exhibits the enhanced flexural modulus of 2.9 MPa, a satisfying sound absorption performance at low frequencies with Modified Sound Absorption Average (MSAA) of 0.08 (for a sample thickness of only 5 mm), and an outstanding flame retardancy behavior with the peak of heat release rate (pHRR) of 109 W/g and the total heat release of 5 kJ/g in the pyrolysis combustion flow calorimeter (PCFC) analysis.

Polymer nanocomposites are heterogeneous systems, mainly composed of one polymer and one or more nanoscale particles, showing a wide range of properties depending on the properties of the parent polymer and nanoparticle, composition, microstructure, and particularly the status quo of interfacial interaction between the polymer matrix and nanoparticle. Flame-retardant (FR) nonhalogenated nanocomposites are solutions to inadequate flame retardancy of polymers, but FR nanocomposites are in early stages of their development period. Although there are plenty of reports on the use of nanoparticles in polymers from different families directed toward the analysis of their flame retardancy performances, there is no comprehensive framework to classify polymer nanocomposites based on the performance of nanoparticles’ flame retardancy performance. The main reason for the relatively slow growth in nanomaterial usage in flame retardancy is the lack of efficiency of nanoscale additives compared with conventional FRs. This is why a great body of research in this field has been devoted to explore the effect of the combined use of nanoparticles and conventional micrometer-sized FRs in polymers. For instance, no complete image has been provided by researchers on the FR efficiency of nanoparticles in polymer matrices. Moreover, there is no universal criterion as a practical measure for flame retardancy of nanoparticles, arising from the personalization and/or predilection of opinions of researchers working in the field with their own preconceptions and partialities. This chapter provides an overview of available data and presents the recent progress in the flame retardancy of polymer nanocomposites with the aim of classification of reports on the basis of the performance of nanoparticles of different families (mineral, metal oxide, silicone-based, and carbon-based nanoparticles) by their qualification (Poor, Good, and Excellent) in terms of a newly introduced measure for flame retardancy performance analysis, known as the flame retardancy index (FRI). FRI is a dimensionless universal index that allows comparison between the levels of flame retardancy performance of nanocomposites based on cone calorimetry data.

International audience; Transparency is a crucial factor in developing functional and decorative thin films and coatings, but incorporation of nanoparticles into organic resins for improving their properties quite often makes them opaque. In this work, photophysical properties of epoxy/layered double hydroxide (LDH) nanocomposite coatings were correlated with the dispersion state of LDH in the epoxy resin. The quality of solid epoxy network was assessed in terms of the Cure Index (CI) in relation to the transparency of the films containing 0.1, 0.5, 0.7, 1.0, and 3.0 wt% Mg–Al–LDH and Zn–Al–LDHs. At high loadings, direct transmittance (YDirect) decreased, while the light scattering in the coatings improved with respect to the neat epoxy. The highest Zn–Al–LDH loading (3.0 wt%) slightly deteriorated the transparency (YDirect = 93.3), but it was still higher than that of epoxy nanocomposite containing 0.5 wt% Mg–Al–LDH (YDirect = 89.8). A Good label was assigned to the epoxy nanocomposites containing up to 1.0 wt% Zn–Al–LDH, while epoxy/Mg–Al–LDH nanocomposites were Poor in terms of the CI labeling when Mg–Al–LDH content was more than 0.1 wt%. An increase of about 28 °C in the Tg value after the addition of 0.1 wt% Zn–Al–LDH indicated that Zn–Al–LDH can make strong the interaction between the epoxy matrix and nanoplatelets. However, decrease in the Tg of the epoxy/Mg–Al–LDH nanocomposites was a signature of the weak interactions between the Mg–Al–LDH nanoplatelets ‎and epoxy matrix due to inappropriate dispersion. In general, it was revealed for the first time that the CI enables correlating the chemical crosslinking with the photophysical properties of the epoxy/LDH nanocomposites.

3D printing is the best way to the computerized manufacture of complex geometries for advanced technologies. Because of precise dimension and shape of 3D-printed objects, design criteria are meticulously optimized in 3D printing processes. Nevertheless, achieving 3D printable polymers has always been associated with the consequence of poor mechanical properties, which necessitated the use of reinforcing agents. Typically, neat polymers cannot fulfill the final application requirements. The use of nanomaterials enhances polymer properties. Based on final application, materials should be selected carefully to achieve a printable material along with appropriate properties. 3D-printed nanocomposites have been considered in various applications from electronic to biomedical industry. Designing 3D-printed nanocomposites as biomaterials, mainly for medical applications, was the subject of numerous scientific reports. It was recognized that designing appropriate nanocomposites for 3D printing necessitates collecting profound knowledge about materials’ structure and their rheological properties. However, classification of reports on 3D-printed biomaterials for medical application was the subject of a few reports. In this chapter, 3D-printed nanocomposites are reviewed in view of mechanical and rheological properties for biomaterials applications.

Ionic liquid-based N-octadecyl-N'-octadecyl imidazolium iodide functionalized layered double hydroxide (LDH-IM) was synthesized for manufacturing high-performance epoxy nanocomposites. Nonisothermal differential scanning calorimetry (DSC) was performed to study cure kinetics of epoxy reinforced قث with LDH and LDH-IM. Incorporation of Mg-Al-CO3 LDH into epoxy hindered the curing reaction, as detected by dimensionless Cure Index (CI). By contrast, epoxy/LDH-IM cured Good and Excellent due to imidazolium ionic liquid. Higher activation energy for completely cured epoxy/LDH-IM nanocomposite was obtained compared to epoxy and epoxy/LDH nanocomposites. The curing reaction rate was obtained by calculation of the orders of instantaneous autocatalytic and non-catalytic reactions, and optimal kinetic parameters based on isoconversional methods were in good agreement with experimental cure reaction rates. Lower value of Tg for epoxy/LDH nanocomposite compared to the neat epoxy signified weak interactions between Mg-Al-CO3-LDH and epoxy matrix, while a higher Tg was obtained for epoxy/LDH-IM. Network degradation kinetics of the samples was also investigated. The higher decomposition activation energy for epoxy/LDH-IM approved strong interfacial adhesion in the assigned system. The highly reactive nature of the developed LDH-IM gives reason for its usage for developing highly curable epoxy with high thermal and mechanical properties.

Polymers offer several appealing features, mainly because of their adjustable architecture, but they suffer from low thermal stability and high flammability. Reactive and functional polymers are known for superior properties compared to the corresponding pure polymers, but their thermal stability and decomposition mechanisms have not systematically been addressed in the literature. Typically, different macromolecular natures in these polymer families give rise to a dissimilar degradation behavior, especially for biodegradable polymers. The additional reactivity resulting from additives or the second polymer in blends and nanocomposites should also be considered in the stability of the polymers. Taking into account such complexities, this chapter describes the state of fire behavior of reactive polymers.