Evaluating the osteogenic properties of polyhydroxybutyrate-zein/multiwalled carbon nanotubes (MWCNTs) electrospun composite scaffold for bone tissue engineering applications

In this investigation, the electrospun nanocomposite scaffolds were developed utilizing poly-3-hydroxybutyrate (PHB), zein, and multiwalled carbon nanotubes (MWCNTs) at varying concentrations of MWCNTs including 0.5 and 1 wt%. Based on the SEM evaluations, the scaffold containing 1 wt% MWCNTs (PZ-1C) exhibited the lowest fiber diameter (384 ± 99 nm) alongside a suitable porosity percentage. The presence of zein and MWCNT in the chemical structure of the scaffold was evaluated by FTIR. Furthermore, TEM images revealed the alignment of MWCNTs with the fibers. Adding 1 % MWCNTs to the PHB-zein scaffold significantly enhanced tensile strength by about 69 % and reduced elongation by about 31 %. Hydrophilicity, surface roughness, crystallinity, and biomineralization were increased by incorporating 1 wt% MWCNTs, while weight loss after in vitro degradation was decreased. The MG-63 cells exhibited enhanced attachment, viability, ALP secretion, calcium deposition, and gene expression (COLI, RUNX2, and OCN) when cultivated on the scaffold containing MWCNTs compared to the scaffolds lacking MWCNTs. Moreover, the study found that MWCNTs significantly reduced platelet adhesion and hemolysis rates below 4 %, indicating their favorable anti-hemolysis properties. Regarding the aforementioned results, the PZ-1C electrospun composite scaffold is a promising scaffold with osteogenic properties for bone tissue engineering applications.

Preparation of Spherical Cellulose Nanocrystals from Microcrystalline Cellulose by Mixed Acid Hydrolysis with Different Pretreatment Routes

Spherical cellulose nanocrystal (CNC), as a high value cellulose derivative, shows an excellent application potential in biomedicine, food packaging, energy storage, and many other fields due to its special structure. CNC is usually prepared by the mixed acid hydrolysis method from numerous cellulose raw materials. However, the pretreatment route in preparing spherical CNC from cellulose fiber is still used when choosing microcrystalline cellulose (MCC) as the raw material, which is not rigorous and economical. In this work, pretreatment effects on the properties of spherical CNC produced from MCC by mixed acid hydrolysis were systematically studied. Firstly, the necessity of the swelling process in pretreatment was examined. Secondly, the form effects of pretreated MCC (slurry or powder form) before acid hydrolysis in the preparation of spherical CNC were carefully investigated. The results show that the swelling process is not indispensable. Furthermore, the form of pretreated MCC also has a certain influence on the morphology, crystallinity, and thermal stability of spherical CNC. Thus, spherical CNC with different properties can be economically prepared from MCC by selecting different pretreatment routes through mixed acid hydrolysis.

Hemp Stem Epidermis and Cuticle: From Waste to Starter in Bio-Based Material Development

Nowadays, hemp farmers are facing an urgent problem related to plant stem disposal after seed harvesting. In this work, the commonly discarded epidermis and cuticle of hemp stems were valorized, turning them towards a sustainable recycling and reuse, contributing to the circular economy concept. Cellulose deprived of amorphous regions was obtained by a green process consisting of an ethanolic ultrasound-assisted maceration followed by mild bleaching/hydrolysis. The obtained hemp cellulose was esterified with citric acid resulting in a 1.2-fold higher crystallinity index and 34 °C lower T_g value compared to the non-functionalized hemp cellulose. Green innovative biocomposite films were developed by embedding the modified cellulose into PLA by means of an extrusion process. The structural and morphological characterization of the obtained biocomposites highlighted the functionalization and further embedment of cellulose into the PLA matrix. Attenuated Total Reflectance–Fourier Transform Infrared spectroscopy (ATR-FTIR) results suggested physical and chemical interactions between PLA and the organic filler in the biofilms, observing a homogeneous composition by Field Emission-Scanning Electron Microscopy (FESEM). Moreover, some increase in thermal stability was found for biocomposites added with 5%wt of the hemp cellulose filler. The obtained results highlighted the feasible recovery of cellulose from hemp stem parts of disposal concern, adding value to this agro-waste, and its potential application for the development of novel biocomposite films to be used in different applications.

The healing of bone defects by cell-free and stem cell-seeded 3D-printed PLA tissue-engineered scaffolds

In this paper, the in-vivo healing of critical-sized bony defects by cell-free and stem cell-seeded 3D-printed PLA scaffolds was studied in rat calvaria bone. The scaffolds were implanted in the provided defect sites and histological analysis was conducted after 8 and 12 weeks. The results showed that both cell-free and stem cell-seeded scaffolds exhibited superb healing compared with the empty defect controls, and new bone and connective tissues were formed in the healing site after 8 and 12 weeks, postoperatively. The higher filled area, bone formation and bone maturation were observed after 12 weeks, particularly for PLA + Cell scaffolds.

Temperature-Triggered Supramolecular Assembly of Organic Semiconductors

Supramolecular assembly is a promising bottom-up approach for producing materials that behave as charge transporting components in electronic devices. Although extensive advances have been made during the past two decades, formidable challenges exist in controlling the local randomness present in supramolecular assemblies. Here, a temperature-triggered supramolecular assembly strategy using heat to heal defects and disorders is reported. The central concept of the molecular design-named the "Tetris strategy" in this research-is to: i) increase the rotational freedom of the molecules through thermal perturbation, ii) induce conformation-fitting of adjacent molecules through two different kinds of intermolecular [π···π] interactions, and finally iii) lock the nearby molecules in inactive co-conformations. Experimentally, upon heating to 57 °C, amorphous solid-state films undergo spontaneous assembly, leading to the growth of uniform and highly ordered microwire arrays. Temperature-triggered supramolecular assembly provides an approach closer to the precision control of assembled structures and presents with a broad canvas to work on in approaching a new generation of supramolecular electronics. Tetris is a registered trademark of Tetris Holding, LLC, used with permission.

Preparation and separation of pure spherical cellulose nanocrystals from microcrystalline cellulose by complex enzymatic hydrolysis

Spherical cellulose nanocrystals (CNCs), as a new and high value cellulose derivative, shows excellent application potential in many fields due to its special structure. The accurate and effective separation of pure spherical CNCs lays foundation for its further application. In this work, spherical CNCs were prepared by enzymatic hydrolysis of microcrystalline cellulose (MCC) with complex enzymes. In order to determine the optimal separation conditions of pure spherical CNCs, turbidity and Zeta potential were used to analyze the influence of pH on system stability, and the size and morphology of samples were characterized by DLS, AFM and SEM. The results showed that spherical CNCs with particle size of 24-76 nm can be separated from large particles with the help of alkali (pH = 9) dispersion and centrifugation speed of 3000 rpm. After three acid (pH = 4) washes, pure spherical CNCs were extracted and reducing sugars and enzyme proteins were removed. Compared with MCC, spherical CNCs had lower crystallinity but stronger reactivity and higher heat transfer. DTG results showed that the maximum weight loss temperature of spherical CNCs prepared by enzymatic hydrolysis was 309 °C.

Cellulose nanosphere: Preparation and applications of the novel nanocellulose

Over the past few years, cellulose nanosphere (CNS) has gained growing attention and rapid development. As a new type of nanocellulose materials, CNS can be prepared from native cellulose by using methods which have been adopted extensively to prepare the well-known nanocelluloses, i.e., cellulose nanofiber and cellulose nanocrystal. The particular interest is that the regenerated cellulose and mercerized cellulose can also be used as important feedstocks to produce CNS. In this review, the preparation methods of CNS are described and discussed, via both top-down processes, including chemical, mechanical, and enzymolysis ones, and bottom-up processes by using various cellulose I and II starting materials. This review also highlights the researches relative to cellulose composite nanospheres, and summarizes the applications of spherical cellulose-based nanoparticles. Finally, the future challenges and opportunities of CNS are prospected in this work.

Impact of the Incorporation of Nano-Sized Cellulose Formate on the End Quality of Polylactic Acid Composite Film

Polylactic acid (PLA) films with good sustainable and biodegradable properties have been increasingly explored recently, while the poor mechanical property of PLA limits its further application. Herein, three kinds of nano-sized cellulose formate (NCF: cellulose nanofibril (CNF), cellulose nanocrystal (CNC), and regenerated cellulose formate (CF)) with different properties were fabricated via a one-step formic acid (FA) hydrolysis of tobacco stalk, and the influence of the properties of NCF with different morphologies, crystallinity index (CrI), and degree of substitution (DS) on the end quality of PLA composite film was systematically compared. Results showed that the PLA/CNC film showed the highest increase (106%) of tensile strength compared to the CNF- and CF-based films, which was induced by the rod-like CNC with higher CrI. PLA/CF film showed the largest increase (50%) of elongation at the break and more even surface, which was due to the stronger interfacial interaction between PLA and the CF with higher DS. Moreover, the degradation property of PLA/CNF film was better than that of other composite films. This fundamental study was very beneficial for the development of high-quality, sustainable packaging as an alternative to petroleum-based products.

Rochelle Salt-Based Ferroelectric and Piezoelectric Composite Produced with Simple Additive Manufacturing Techniques

More than one century ago, piezoelectricity and ferroelectricity were discovered using Rochelle salt crystals. Today, modern societies are invited to switch to a resilient and circular economic model. In this context, this work proposes a method to manufacture piezoelectric devices made from agro-resources such as tartaric acid and polylactide, thereby significantly reducing the energy budget without requiring any sophisticated equipment. These piezoelectric devices are manufactured by liquid-phase epitaxy-grown Rochelle salt (RS) crystals in a 3D-printed poly(Lactic acid) (PLA) matrix, which is an artificial squared mesh which mimics anatomy of natural wood. This composite material can easily be produced in any fablab with renewable materials and at low processing temperatures, which reduces the total energy consumed. Manufactured biodegradable samples are fully recyclable and have good piezoelectric properties without any poling step. The measured piezoelectric coefficients of manufactured samples are higher than many piezoelectric polymers such as PVDF-TrFE.

Functionality of Cellulose Nanofiber as Bio-Based Nucleating Agent and Nano-Reinforcement Material to Enhance Crystallization and Mechanical Properties of Polylactic Acid Nanocomposite

Polylactic acid (PLA), a potential alternative material for single use plastics, generally portrays a slow crystallization rate during melt-processing. The use of a nanomaterial such as cellulose nanofibers (CNF) may affect the crystallization rate by acting as a nucleating agent. CNF at a certain wt.% has been evidenced as a good reinforcement material for PLA; nevertheless, there is a lack of information on the correlation between the amount of CNF in PLA that promotes its functionality as reinforcement material, and its effect on PLA nucleation for improving the crystallization rate. This work investigated the nucleation effect of PLA incorporated with CNF at different fiber loading (1-6 wt.%) through an isothermal and non-isothermal crystallization kinetics study using differential scanning calorimetry (DSC) analysis. Mechanical properties of the PLA/CNF nanocomposites were also investigated. PLA/CNF3 exhibited the highest crystallization onset temperature and enthalpy among all the PLA/CNF nanocomposites. PLA/CNF3 also had the highest crystallinity of 44.2% with an almost 95% increment compared to neat PLA. The highest crystallization rate of 0.716 min^-1 was achieved when PLA/CNF3 was isothermally melt crystallized at 100 °C. The crystallization rate was 65-fold higher as compared to the neat PLA (0.011 min^-1). At CNF content higher than 3 wt.%, the crystallization rate decreased, suggesting the occurrence of agglomeration at higher CNF loading as evidenced by the FESEM micrographs. In contrast to the tensile properties, the highest tensile strength and Young's modulus were recorded by PLA/CNF4 at 76.1 MPa and 3.3 GPa, respectively. These values were, however, not much different compared to PLA/CNF3 (74.1 MPa and 3.3 GPa), suggesting that CNF at 3 wt.% can be used to improve both the crystallization rate and the mechanical properties. Results obtained from this study revealed the dual function of CNF in PLA nanocomposite, namely as nucleating agent and reinforcement material. Being an organic and biodegradable material, CNF has an increased advantage for use in PLA as compared to non-biodegradable material and is foreseen to enhance the potential use of PLA in single use plastics applications.

Preparation of formyl cellulose and its enhancement effect on the mechanical and barrier properties of polylactic acid films

Cellulose was modified by formic acid to prepare formyl cellulose (FC). The amount of formyl groups in FC was adjusted by controlling the reaction time, reaction temperature, and formic acid concentration. Then, FC was used to reinforce polylactic acid (PLA) films prepared by solution casting. Scanning electron microscopy (SEM) shows that long rod-like cellulose particles were broken into short rods after formylation and the introduction of FC made PLA surface rougher. The mechanical properties of PLA/FC films were improved by the inclusion of FC. Compared to pure PLA film, the PLA/FC composite film with 1 wt% FC (containing 15.79% formyl groups) showed a 48.59% increase in tensile strength and a 346% increase in Young's modulus. The addition of FC also resulted in better water barrier properties. The moisture absorption capacity and water vapor permeability were 40.56% and 51.43% lower than those of the pure-PLA film. The enhancement in properties for PLA/FC composites could be ascribed to the improved compatibility between PLA and cellulose with the introduction of hydrophobic formate groups. The PLA/FC composite films developed in this work could be highly potential for food packaging.

Influence of drying methods on the structure and properties of cellulose formate and its application as a reducing agent

Cellulose formate (CF) with surface formyl groups can be prepared through the esterification between cellulose and formic acid (FA). The properties of CF are sensitive to temperature, which is of great importance for its end application. In this work, the effect of four drying methods on the structure and properties of the resultant CF was investigated. Results showed that the CF samples as special cellulose nanofibrils with cellulose II crystal form and fibrous structure were sensitive to drying temperature and drying time. The freeze-dried CF sample maintained its original structure, while the air-dried and oven-dried CF samples with amorphous structure showed the aggregation state. Furthermore, the CF/Ag composites were prepared using silver mirror reaction where the never dried CF was used as a reducing agent. SEM and TEM images exhibited a large number of Ag nanoparticles with the diameter of 20-50 nm on the surface of CF samples. As expected, the fabricated CF/Ag composites showed strong antibacterial activity against both Escherichia coli and Bacillus subtilis, and thus the prepared composites have great potential applications in antibacterial daily necessities and medical supplies.

Structure and Properties of Polylactic Acid Biocomposite Films Reinforced with Cellulose Nanofibrils

Polylactic acid (PLA) is one of the most promising biodegradable and recyclable thermoplastic biopolymer derived from renewable feedstock. Nanocellulose reinforced PLA biocomposites have received increasing attention in academic and industrial communities. In the present study, cellulose nanofibrils (CNFs) was liberated by combined enzymatic pretreatment and high-pressure homogenization, and then subsequently incorporated into the PLA matrix to synthesize PLA/CNF biocomposite films via solution casting and melt compression. The prepared PLA/CNF biocomposite films were characterized in terms of transparency (UV-Vis spectroscopy), chemical structure (attenuated total reflectance-Fourier transform infrared, ATR-FTIR; X-ray powder diffraction, XRD), thermal (thermogravimetric analyzer, TGA; differential scanning calorimetry, DSC), and tensile properties. With 1.0–5.0 wt % additions of CNF to the PLA matrix, noticeable improvements in thermal and physical properties were observed for the resulting PLA/CNF biocomposites. The 2.5 wt % addition of CNF increased the tensile strength by 8.8%. The T_onset (initial degradation temperature) and T_max (maximum degradation temperature) after adding 5.0 wt % CNF was increased by 20 °C, and 10 °C, respectively in the nitrogen atmosphere. These improvements were attributed to the good dispersibility and improved interfacial interaction of CNF in the PLA matrix.

Recycling of viscose yarn waste through one-step extraction of nanocellulose

Textile manufacturing industries generate large amounts of viscose yarn waste (VW) that causes serious environmental pollution. In this study, VW was used as raw material to successfully extract nanocellulose (NC) in a facile one-step extraction process, without any pretreatment. Different hydrolysis reaction times (5-60 min) were employed, and the extracted material was characterized by Fourier transform infrared spectroscopy, X-ray diffraction, scanning and transmission electron microscopies, atomic force microscopy, and thermogravimetric analysis. Interestingly, it was possible to obtain NC in only 5 min of reaction without any pretreatment and with an increase of 50% in the crystallinity, which was attributed to the pretreatments VW undergone in textile industry that swell cellulose chains and make them more accessible to further reactions. The higher crystallinity index was observed after 30 min of reaction (87%), and through microscopy, it was verified that the morphology of the VW was completely changed to irregular nanoparticles with average size of 42 nm. The obtained NC showed interesting properties to be used in several potential applications, including stabilization of oil/water Pickering emulsions. These results indicate that VW is an attractive source to obtain NC, making the extraction of NC from VW a value-added alternative to recycle this textile waste.

Nanocellulose-based polymer hybrids and their emerging applications in biomedical engineering and water purification

Nanocellulose, derived from cellulose hydrolysis, has unique optical and mechanical properties, high surface area, and good biocompatibility. It is frequently used as a reinforcing agent to improve the native properties of materials. The presence of functional groups in its surface enables the alteration of its behavior and its use under different conditions. Nanocellulose is typically used in the form of cellulose nanocrystals (CNCs), cellulose nanofibers (CNFs), or bacterial nanocellulose (BNC). CNCs and CNFs have a high aspect ratio with typical lengths of ∼100-250 nm and 0.1-2 μm, respectively; BNC is nanostructured cellulose produced by bacteria. Nanohybrid materials are a combination of organic or inorganic nanomaterials with macromolecules forming a single composite and typically exhibit superior optical, thermal, and mechanical properties to those of native polymers, owing to the greater interactions between the macromolecule matrix and the nanomaterials. Excellent biocompatibility and biodegradability make nanocellulose an ideal material for applications in biomedicine. Unlike native polymers, nanocellulose-based nanohybrids exhibit a sustained drug release ability, which can be further optimized by changing the content or chemical environment of the nanocellulose, as well as the external stimuli, such as the pH and electric fields. In this review, we describe the process of extraction of nanocellulose from different natural sources; its effects on the structural, morphological, and mechanical properties of polymers; and its various applications.

Properties of Polylactic Acid Reinforced by Hydroxyapatite Modified Nanocellulose

Polylactic acid (PLA) is one of the most promising bio-based materials, but its inherent hydrophobicity limits its application. Although nanocellulose (NCC) is a desirable reinforcement for PLA, the poor interface compatibility between the two has been a challenge. In this work, hydroxyapatite (HAP) modified NCC was prepared, and the obtained NCC/HAP reinforcement was used to prepare PLA/NCC-HAP composites. Different ratios of NCC to HAP were studied to explore their effects on the mechanical and thermodynamic properties of the composites. When the ratio of NCC to HAP was 30/70, the tensile strength and tensile modulus of the composite film reached 45.6 MPa and 2.34 GPa, respectively. Thermogravimetric analysis results indicate that thermal stability of the composites was significantly improved compared with pure PLA, reaching 346.6 °C. The above revelations show that NCC/HAP significantly improved the interface compatibility with PLA matrix.

Active Food Packaging Based on Biopolymers and Aroma Compounds: How to Design and Control the Release

Aroma compounds are known to be efficient active agents for a broad range of applications (antimicrobial, anti-oxidant, insect repellent…) that are highly sought when aiming at extending shelf life of food or biological products. However, they are intrinsically odorant and volatile at ambient temperature, which restricts the processing routes used to introduce them in a polymeric matrix and can affect their mode of action and limit efficiency. Indeed, due to their high sensitivity toward temperature they can be lost or transformed during processing. Acting after being released in the headspace, their concentration has to be controlled to avoid any odorant contamination of the targeted products. Hence, the ability for an aroma compound to be retained in a polymeric matrix, and then released when submitted to a triggering effect, are the two main requirements that should be satisfied. The volatile nature of the aroma compound offer the possibility when introduce in the packaging to act by direct or indirect contact with the product and thus to be used in different ways; as a coating layer directly applied on the product surface, as a self-supported film or as coated paper when associated with a paper sheet, as well as an object that could be inserted in the package. As biopolymers such as proteins and polysaccharides are able to retain aroma compounds but also to favor their release by modification of their structure when the relative humidity (RH) and temperature change, they are relevant carriers of these specific aroma compounds. Examples of how active packaging systems with limonene, eugenol and carvacrol as active agents were designed and elaborated. These examples will be presented with a special focus on the processing conditions and the way to improve their aroma compound retention and the release control (biopolymer nature, cyclodextrin clay addition…). Avrami's equation has been used to model the transfer of aroma compound and to advantageously compare it taking into account the mechanism in relation to the biopolymer structural changes.

Influence of poly(lactide) stereocomplexes as nucleating agents on the crystallization behavior of poly(lactide)s

The influence of the addition of linear and four-arm poly(lactide) stereocomplexes on the crystallization behavior of poly(l-lactide) and poly(d-lactide) from the molten state was investigated.

Understanding thermal decomposition kinetics of flame-retardant thermoset polylactic acid

The Flynn–Wall–Ozawa method was applied to study the local activation energy of flame retardant thermoset PLA, and the results showed that with an increase of conversion of thermal degradation, the local activation energy was increased slowly. When the conversion of thermal degradation was under 15%, the activation energy of flame retardant thermoset PLA was lower than that of thermoset PLA, attributed to the low bond energy of P–C bond. When the conversion of thermal degradation exceeded 15%, the dehydration charcoal effect of phosphorous compound slowed down the process of thermal degradation, and the activation energy of flame retardant thermoset PLA was higher than that of thermoset PLA, indicating that the addition of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) enhances the thermal stability of thermoset PLA. The Coats–Redfern method and invariant kinetic parameters method were used to understand kinetics details about this process including the activation energy and apparent pre-exponential factor, and estimated contribution ratios for the 18 kinetic functions. The results showed that the addition of DOPO didn't impact the most important mechanism of thermal degradation but changed the contribution ratios of the 18 kinetic functions. According to the functional relationship between decomposition rate with temperature and quality conversion rate, three-dimension surface plots were made to understand the change regulation of decomposition rate. We found that the addition of DOPO reduced the decomposition rate of thermoset PLA, attributing to the dehydration charcoal effect of phosphorous compound which restrained the interesterification of PLA, and thus enhancing the thermal stability of thermoset PLA.

The Flynn–Wall–Ozawa method was applied to study the local activation energy of flame retardant thermoset PLA, and the results showed that with an increase of conversion of thermal degradation, the local activation energy was increased slowly.

Current progress in production of biopolymeric materials based on cellulose, cellulose nanofibers, and cellulose derivatives

Cellulose has attracted considerable attention as the strongest potential candidate feedstock for bio-based polymeric material production. During the past decade, significant progress in the production of biopolymers based on different cellulosic forms has been achieved. This review highlights the most recent advances and developments in the three main routes for the production of cellulose-based biopolymers, and discusses their scope and applications. The use of cellulose fibers, nanocellulose, and cellulose derivatives as fillers or matrices in biocomposite materials is an efficient biosustainable alternative for the production of high-quality polymer composites and functional polymeric materials. The use of cellulose-derived monomers (glucose and other platform chemicals) in the synthesis of sustainable biopolymers and functional polymeric materials not only provides viable replacements for most petroleum-based polymers but also enables the development of novel polymers and functional polymeric materials. The present review describes the current status of biopolymers based on various forms of cellulose and the scope of their importance and applications. Challenges, promising research trends, and methods for dealing with challenges in exploitation of the promising properties of different forms of cellulose, which are vital for the future of the global polymeric industry, are discussed. Sustainable cellulosic biopolymers have potential applications not only in the replacement of existing petroleum-based polymers but also in cellulosic functional polymeric materials for a range of applications from electrochemical and energy-storage devices to biomedical applications.

From Cellulose Nanospheres, Nanorods to Nanofibers: Various Aspect Ratio Induced Nucleation/Reinforcing Effects on Polylactic Acid for Robust-Barrier Food Packaging

The traditional approach toward improving the crystallization rate as well as the mechanical and barrier properties of poly(lactic acid) (PLA) is the incorporation of nanocelluloses (NCs). Unfortunately, little study has been focused on the influence of the differences in NC morphology and dimensions on the PLA property enhancement. Here, by HCOOH/HCl hydrolysis of lyocell fibers, microcrystalline cellulose (MCC), and ginger fibers, we unveil the preparation of cellulose nanospheres (CNS), rod-like cellulose nanocrystals (CNC), and cellulose nanofibers (CNF) with different aspect ratios, respectively. All the NC surfaces were chemically modified by Fischer esterification with hydrophobic formate groups to improve the NC dispersion in the PLA matrix. This study systematically compared CNS, CNC, and CNF as reinforcing agents to induce different kinds of heterogeneous nucleation and reinforce the effects on the properties of PLA. The incorporation of three NCs can greatly improve the PLA crystallization ability, thermal stability, and mechanical strength of nanocomposites. At the same NC loading level, the PLA/CNS showed the highest crystallinity (19.8 ± 0.4%) with a smaller spherulite size (33 ± 1.5 μm), indicating that CNS, with its high specific surface area, can induce a stronger heterogeneous nucleation effect on the PLA crystallization than CNC or CNF. Instead, compared to PLA, the PLA/CNF nanocomposites gave the largest Young's modulus increase of 350 %, due to the larger aspect ratio/rigidity of CNF and their interlocking or percolation network caused by filler-matrix interfacial bonds. Furthermore, taking these factors of hydrogen bonding interaction, increased crystallinity, and interfacial tortuosity into account, the PLA/CNC nanocomposite films showed the best barrier property against water vapor and lowest migration levels in two liquid food simulates (well below 60 mg kg^-1 for required overall migration in packaging) than CNS- and CNF-based films. This comparative study was very beneficial for selecting reasonable nanocelluloses as nucleation/reinforcing agents in robust-barrier packaging biomaterials with outstanding mechanical and thermal performance.

Non-isothermal crystallization kinetics of ramie fiber-reinforced polylactic acid biocomposite

The addition of RF weakened the interaction between PLA chains and reduced the energy barrier of PLA during crystallization.

Insight into the role of bound water of a nucleating agent in polymer nucleation: a comparative study of anhydrous and monohydrated orotic acid on crystallization of poly(l-lactic acid)

The bound water of orotic acid and its dehydration transition play a negative role in nucleation effects on PLLA crystallization.

Fully biobased robust biocomposites of PLA with assisted nucleation by monodispersed stereocomplexed polylactide particles

Fully biodegradable biocomposites are a desirable choice among the synthetic plastics due to their increasing adverse ecological issues.

Crystallization behaviors of polyarylene ether nitrile filled in multi-walled carbon nanotubes

The isothermal and dynamic crystallization behaviors of PEN filled in CNT are studied. The PEN filled in CNT cannot crystallize without shearing. By shearing, the shear stress transmits from CNT to the PEN and induces the crystallization of it.