A sustainable process to 100%bio-based nylons integrated chemical and biological conversion of lignocellulose

Considerable progress has been made in recent years to the development of sustainable polymers from bio-based feedstocks.In this study,100%bio-based nylons were prepared via an integrated chemical and biological process from lignocellulose.These novel nylons were obtained by the melt polymerization of 3-propyladipic acid derived from lignin and 1,5-pentenediamine/1,4-butanediamine derived from carbohydrate sugar.Central to the concept is a three-step noble metal free catalytic chemical funnelling sequence(Raney Ni mediated reductive catalytic fractionation-reductive funnelling-oxidative funnelling),which allowed for obtaining a single component 3-propyladipic acid from lignin with high efficiency.The structural and thermodynamic properties of the obtained nylons have been systematically investigated,and thus obtained transparent bio-based nylons exhibited higher Mw(>32,000)and excellent thermal stability(Td5%>265℃).Considering their moderate Tg and good melt strength,these transparent bio-based nylons could serve as promising functional additives or temperature-responsive materials.

Aqueous-phase reforming of hydroxyacetone solution to bio-based H_(2)over supported Pt catalysts

Aqueous-phase reforming(APR)is an attractive process to produce bio-based hydrogen from waste biomass streams,during which the catalyst stability is often challenged due to the harsh reaction conditions.In this work,three Pt-based catalysts supported on C,AlO(OH),and ZrO_(2)were investigated for the APR of hydroxyacetone solution in afixed bed reactor at 225℃and 35 bar.Among them,the Pt/C catalyst showed the highest turnover frequency for H_(2)production(TOF of 8.9 molH_(2)molPt^(-1)min^(-1))and the longest catalyst stability.Over the AlO(OH)and ZrO_(2)supported Pt catalysts,the side reactions consuming H_(2),formation of coke,and Pt sintering result in a low H_(2)production and the fast catalyst deactivation.The proposed reaction pathways suggest that a promising APR catalyst should reform all oxygenates in the aqueous phase,minimize the hydrogenation of the oxygenates,maximize the WGS reaction,and inhibit the condensation and coking reactions for maximizing the hydrogen yield and a stable catalytic performance.

Elastic Bio-based Polyurethane Nanofibrous Membrane with Robust Waterproof and Breathable Properties

Elastic bio-based waterproof and breathable membranes(EBWBMs) allow the passage of water vapor effectively and resist the penetration of liquid water,making it ideal for use under extreme conditions.In this study,we used a facile strategy to design the bio-based polyurethane(PU) nanofibrous membranes with the nanoscale porous structure to provide the membranes with high waterproof and breathable performances.The optimization of nanofibrous membrane formation was accomplished by controlling the relative ambient humidity to modulate the cooperating effects of charge dissipation and non-solvent-induced phase separation.The obtained EBWBMs showed multiple functional properties,with a hydrostatic pressure of 86.41 kPa and a water vapor transmission(WVT) rate of 10.1 kg·m^(-2)·d^(-1).After 1 000 cycles of stretching at 40% strain,the EBWBMs retained over 59% of the original maximum stress and exhibited an ideal elasticity recovery ratio of 85%.Besides,even after 80% deformation,the EBWBMs still maintained a hydrostatic pressure of 30.65 kPa and a WVT rate of 13.6 kg·m^(-2)·d^(-1),suggesting that bio-based PU nanofibrous membranes could be used for protection under extreme conditions.

Eco-friendly physical blowing agent mass loss of bio-based polyurethane rigid foam materials

Through systematical experiment design, the physical blowing agent(PBA) mass loss of bio-based polyurethane rigid foam(PURF)in the foaming process was measured and calculated in this study, and different eco-friendly PBA mass losses were measured quantitatively for the first time. The core of the proposed method is to add water to replace the difference, and this method has a high fault tolerance rate for different foaming forms of foams. The method was proved to be stable and reliable through the standard deviations σ1and σ2for R1(ratio of the PBA mass loss to the material total mass except the PBA) and R2(ratio of the PBA mass loss to the PBA mass in the material total mass) in parallel experiments. It can be used to measure and calculate the actual PBA mass loss in the foaming process of both bio-based and petroleumbased PURF. The results show that the PBA mass loss in PURF with different PBA systems is controlled by its initial mass content of PBA in PU materials ω. The main way for PBA to dissipate into the air is evaporation/escape along the upper surface of foam. This study further reveals the mechanism of PBA mass loss: the evaporation/escape of PBA along the upper surface of foam is a typical diffusion behavior. Its spread power comes from the difference between the chemical potential of PBA in the interface layer and that in the outside air. For a certain PURF system, R1has approximately linear relationship with the initial mass content of PBA in PU materials ω, which can be expressed by the functional relationship R1= kω, where k is a variable related to PBA’s own attributes.

CO_(2)-Responsive Smart Foams Stabilized by an Extremely Rigid Bio-Based Surfactant

Environment friendly and intelligent surfactants have attracted great attention in recent years.A bio-based CO_(2)responsive surfactant rosin acid dimaleimide choline(R-BMI-C)with an extremely rigid skeleton was prepared using rosin and choline as raw materials by Diels-Alder addition reaction and acid-base neutralization reactions.Its structure was confirmed by IR and^(1)H NMR spectra.The foams’properties of R-BMI-C could be adjusted by bubbling CO_(2)/N_(2)to change the structure of the surfactant.At pH 10.4,R-BMI-C forms an unstable foam with a half-life of 1.5 h.When the pH was reduced to 7.4 by bubbling CO_(2),R-BMI-C forms an extremely stable foam with a half-life of 336 h.The surfactant R-BMI-C changed from bola type to conventional type when bubbling CO_(2).And the internal aggregation structure of R-BMI-C aqueous solution changed from spherical micelles to laminar micelles according to the cryogenic-transmission electron microscope.We know that the lamellar structure tends to adsorb at the air/water interface or is trapped in the foam film,which slows down the foam coarsening and agglomeration process,resulting in a significant increase in foam stability.R-BMI-C could be used in oil extraction,fire-fighting and chemical decontamination due to its excellent foaming,stabilization and defoaming properties.

Fully Bio-Based Composites of Poly(Lactic Acid)Reinforced with Cellulose-Graft-Poly-(ε-Caprolactone)Copolymers

Due to the increasing demand for modified polylactide(PLA)meeting“double green”criteria,the research on sustainable plasticizers for PLA has attracted broad attentions.This study reported an open-ring polymerization method to fabricate cellulose(MCC)-g-PCL(poly(ε-caprolactone))copolymers with a fully sustainable and biodegradable component.MCC-g-PCL copolymers were synthesized,characterized,and used as green plasticizers for the PLA toughening.The results indicated that the MCC-g-PCL derivatives play an important role in the compatibility,crystallization,and toughening of the PLA/MCC-g-PCL composites.The mechanical properties of the fully bio-based PLA/MCC-g-PCL composites were optimized by adding 15 wt%MCC-g-PCL,that is,the elongation at break was 22.6%(~376%higher than that of neat PLA),the tensile strength was 47.3 MPa(comparable to that of neat PLA),and the impact strength was 26 J/m(~130%higher than that of neat PLA).DSC results indicated that MCC-g-PCL reduced the Tg of the PLA blend.When the addition amount was 15 wt%,the Tg of the blend was 58.4°C.Compared with MCC,MCC-g-PCL polyester plasticizer has better thermal stability,T5%(°C)can still be maintained above 300°C.The rheological results showed that MCC-g-PCL acted as a plasticizer,the introduction of PCL flexible chain increased the mobility of PLA molecular chain,and decreased the complex viscosity,storage modulus and loss modulus of PLA blends.The MCC-g-PCL derivatives,as a new green plastic additive,have shown an interesting prospect to prepare fully bio-based composites.

Synthesis,Characterization and Water Absorption Analysis of Highly Hygroscopic Bio-based Co-polyamides 56/66

This study aims to develop highly hygroscopic bio-based co-polyamides(CPs)by melt co-polycondensation of polyamide(PA)56 salt and PA66 salt with varying molar fractions.The functional groups and the chemical structure of the prepared samples were determined by Fourier transform infrared(FTIR)spectroscopy and proton nuclear magnetic resonance(^(1)H-NMR)spectroscopy.The relative viscosity was determined with an Ubbelohde viscometer.The melting behavior and the thermal stability of CPs were investigated by differential scanning calorimetry(DSC)and thermogravimetric analysis(TGA).Furthermore,the water absorption behavior of CP hot-pressed film was studied.The results reveal that the melting point,the crystallization temperature and the crystallinity of CPs firstly decrease and then increase with the molar fraction of PA66 in CPs.The copolymerization of PA56 with PA66 leads to an obvious increase in water absorption.The CPs with PA66 molar fraction of 50%possess a high saturated water absorption rate of 17.6%,compared to 11.6%for pure PA56 and 7.8%for pure PA66.

High Water Resistance and Enhanced Mechanical Properties of Bio-Based Waterborne Polyurethane Enabled by in-situ Construction of Interpenetrating Polymer Network

In this study,acrylic acid was used as a neutralizer to prepare bio-based WPU with an interpenetrating polymer network structure by thermally induced free radical emulsion polymerization.The effects of the content of acrylic acid on the properties of the resulting waterborne polyurethane-poly(acrylic acid)(WPU-PAA)dispersion and the films were systematically investigated.The results showed that the cross-linking density of the interpenetrating network polymers was increased and the interlocking structure of the soft and hard phase dislocations in the molecular segments of the double networks was tailored with increasing the content of acrylic acid,leading to enhancement of the mechanical properties and water resistance of WPU-PAA films.Notably,with the increase in content of acrylic acid,the tensile strength,Young’s modulus,and toughness of the WPU-PAA-110 film increased by 3 times,and 8 times,and 2.4 times compared with WPU-PAA-80,respectively.The WPU-PAA-100 film showed the best water resistance,and the water absorption rate at 96 h was only 3.27%.This work provided a new design scheme for constructing bio-based WPU materials with excellent properties.

Research Status and Prospects of Bio-based Materials for Grease Barrier Coatings on Paper Food Packaging

Increased environmental and health concerns over the use of plastic packaging or fluorine-containing coatings,in combination with increased market demand for products with a longer shelf life,make bio-based materials one of the most important research candidates for alternative paper packaging materials for oil resistance.These bio-based materials have excellent oxygen and oil barriers,which are critical for food packaging.Moreover,they are biodegradable,naturally renewable,and safe.In this artical,two main groups of bio-based oil repellents for paper food packaging,including polysaccharide-based biopolymers and protein-based biopolymers,are enumerated,and the advantages and weaknesses of bio-based oil repellents are discussed,and effective solutions are proposed.Finally,research status and prospects on the development of bio-based oil-resistant coatings for the food packaging industry are presented.

Recycled, Bio-Based, and Blended Composite Materials for 3D Printing Filament: Pros and Cons—A Review

In recent years, additive manufacturing (AM), known as “3D printing”, has experienced exceptional growth thanks to the development of mechatronics and materials science. Fused filament deposition (FDM) manufacturing is the most widely used technique in the field of AM, due to low operating and material costs. However, the materials commonly used for this technology are virgin thermoplastics. It is worth noting a considerable amount of waste exists due to failed print and disposable prototypes. In this regard, using green and sustainable materials is essential to limit the impact on the environment. The recycled, bio-based, and blended recycled materials are therefore a potential approach for 3D printing. In contrast, the lack of understanding of the mechanism of interlayer adhesion and the degradation of materials for FDM printing has posed a major challenge for these green materials. This paper provides an overview of the FDM technique and material requirements for 3D printing filaments. The main objective is to highlight the advantages and disadvantages of using recycled, bio-based, and blended materials based on thermoplastics for 3D printing filaments. In this work, solutions to improve the mechanical properties of 3D printing parts before, during, and after the printing process are pointed out. This paper provides an overview on choosing which materials and solutions depend on the specific application purposes. Moreover, research gaps and opportunities are mentioned in the discussion and conclusions sections of this study.

Bio-Based Hyperbranched Toughener From Tannic Acid and Its Enhanced Solvent-Free Epoxy Resin with High Performance

It is essential to design economic and efficient tougheners to prepare high-performance epoxy resin;however,this has remained a huge challenge.Herein,an eco-friendly,low-cost,and facile-fabricated bio-based hyperbranched toughener,carboxylic acid-functionalized tannic acid(CATA),was successfully prepared and applicated to the preparation of solvent-free epoxy resins.The mechanical performance,morphology,structural characterization,and thermal characterization of toughened epoxy resin system were studied.The toughened epoxy resin system with only 1.0wt%CATA reached the highest impact strength,111%higher than the neat epoxy resin system.Notably,the tensile strength and elongation at break of toughened epoxy resin systems increased moderately with increasing CATA loading.Nonphase-separated hybrids with significant toughening effect were obtained.Additionally,the thermal stabilities of toughened epoxy resin systems decreased with increasing CATA loading.This study provides an eco-friendly,cost-effective,and facile approach for the preparation of high-performance,solvent-free epoxy resins with potential for practical applications in sealing integrated circuits and electrical devices fields.

Advances in Cadaverine Bacterial Production and Its Applications

Cadaverine. a natural polyamine with multiple bioactivities that is widely distributed in prokaryotes and eukaryotes, is becoming an important industrial chemical. Cadaverine exhibits broad prospects for various applications, especially as an important monomer for bio-based polyamides. Cadaverine-based polyamide PA 5X has broad application prospects owing to its environmentally friendly characteristics and exceptional performance in water absorption and dimensional stability. In this review, we summarize recent findings on the biosynthesis, metabolism, and physiological function of cadaverine in bacteria, with a focus on the regu- latory mechanism of cadaverine synthesis in Escherichia coil （E. coli）. We also describe recent developments in bacterial production of cadaverine by direct fermentation and whole-cell bioconversion, and recent approaches for the separation and purification of cadaverine. In addition, we present an overview of the ap- plication of cadaverine in the synthesis of completely bio-based polyamides. Finally. we provide an outlook and suggest future developments to advance the production of cadaverine from renewable resources.

Spinning from Nature:Engineered Preparation and Application of High-Performance Bio-Based Fibers

Many natural fibers are lightweight and display remarkable strength and toughness.These properties originate from the fibers’hierarchical structures,assembled from the molecular to macroscopic scale.The natural spinning systems that produce such fibers are highly energy efficient,inspiring researchers to mimic these processes to realize robust artificial spinning.Significant developments have been achieved in recent years toward the preparation of high-performance bio-based fibers.Beyond excellent mechanical properties,bio-based fibers can be functionalized with a series of new features,thus expanding their sophisticated applications in smart textiles,electronic sensors,and biomedical engineering.Here,recent progress in the construction of bio-based fibers is outlined.Various bioinspired spinning methods,strengthening strategies for mechanically strong fibers,and the diverse applications of these fibers are discussed.Moreover,challenges in reproducing the mechanical performance of natural systems and understanding their dynamic spinning process are presented.Finally,a perspective on the development of biological fibers is given.

Preparation and Properties of Bio-Based Flame Retardant Polyvinyl Alcohol

Polyvinyl alcohol (PVA) has been widely used in the fields of medical, food and packaging due to its excellentbiocompatibility, good fiber-forming and film-forming properties. However, the high flammability of PVA hasgreatly limited its wider applications. The flame-retardant PVA was prepared by melt blending of a bio-basedflame retardant (prepared from lignin, phosphoric acid and carbamide) with thermoplastic PVA (TPVA). Thechemical structure, morphology, thermal properties, mechanical properties, fire property and fluidity of thisflame retardant PVA were investigated by Fourier transform infrared spectrometer(FTIR), field emission scanning electron microscope(SEM), thermogravimetric analyzer(TGA), impact tester, universal testing machine,horizontal-vertical burning tester, limiting oxygen indexer(LOI) and melt flow rate meter(MFR). The resultsshowed that the prepared flame retardant had good compatibility with the PVA substrate;The impact strength,melt flow rate, fire property and char residue of this PVA material increased with the content of bio-based flameretardant. When the content of flame retardant was of 20%, the five indices including impact strength, meltflow rate, UL-94 level, LOI and char residual were 11.3 KJ/m^(2), 21.2 g/10 min, V-0 UL-94 level, 33.1%, and19.2%, respectively. This research can promote the high-value utilization of lignin and the application ofPVA in the fields of fire protection.

Preparation and Properties of Bio-Based Flame Retardant L-APP/Poly(L-lactic acid)Composites

Poly(L-lactic acid)(PLLA)is a thermoplastic material with complete degradability,high biocompatibility and excellent mechanical properties.It can replace petroleum-based polymers are currently being used in the fields of packaging,agriculture,textiles,medical and so on.However,PLLA’s extremely flammability greatly limits its wider application.An bio-based flame retardant L-APP/PLLA composites was prepared by melt blending of the L-APP and PLLA.The morphology,impact properties,thermal properties and flame retardant properties of composites were investigated by field emission scanning electron microscope(SEM),impact tester,differential scanning calorimeter(DSC),thermogravimetric analyzer(TGA),limiting oxygen indexer(LOI)and horizontalvertical burning tester.The results showed that the degree of crystallization(X_(c))and LOI of L-APP/PLLA composites increased as increasing of L-APP content.What’s more,the impact strength first increased and then decreased,the glass transition temperature(T_(g))and melting temperature(T_(m))do not changed significantly.The impact strength of composites was 9.1 kJ/m^(2) at a 5 wt%loading for L-APP,which was the highest level.When the content of L-APP was 20%,the LOI was 30.8%,the Xc was 42.3%and the UL-94 level was V-0.This research can promote the value-added utilization of lignin and the application of PLLA in the fields of flame retardant materials.

Bio-Based Trivalent Phytate:A Novel Strategy for Enhancing Fire Performance of Rigid Polyurethane Foam Composites

Biomass phytic acid has potential flame retardant value as the main form of phosphorus in plant seeds.In this study,phytate-based flame retardants aluminum phytate(PA-Al)and iron phytate(PA-Fe)were synthesized and characterized.Subsequently,they were introduced into rigid polyurethane foam(RPUF)as flame retardants by one-step water-blown method.The results indicated that RPUF/PA-Fe30 exhibited the highest char residue of 22.1 wt%,significantly higher than 12.4 wt%of RPUF.Cone calorimetry analysis showed that the total heat release(THR)of RPUF/PA-Al30 decreased by 17.0%and total smoke release(TSR)decreased by 22.0%compared with pure RPUF,which were the lowest,demonstrating a low fire risk and good smoke suppression.Thermogravimetric analysis-Fourier transform infrared spectrometer(TG-FTIR)implied the release intensity of flammable gases(hydrocarbons,esters)and toxic gases(isocyanate,CO,aromatic compounds,HCN)of composites was significantly reduced after the addition of PA-Fe.The analysis of char residue indicated that the RPUF composites formed a dense char layer with a high degree of graphitization after the addition of PA-Al/PA-Fe,endowing RPUF composites with excellent mass&heat transmission inhibition effect and fire resistance in the combustion process.

Efficient Thermal Stabilization of Polyvinyl Chloride with Tannin-Ca Complex as Bio-Based Thermal Stabilizer

The potential use of tannin-Ca complex derived from tannins as bio-based thermal stabilizer and antioxidant additive for polyvinyl chloride (PVC) was investigated in this work. For this project, Reapak B-NT/7060 was applied as reference thermal stabilizer. Variable compositions: (1, 2, and 3) part per hundred ratio (phr) of tannin-Ca complex in the presence of 10 phr Dioctyl phthalate (DOP) as plasticizer in all PVC formulations were prepared by melt mixing by internal mixer at 165°C. Tannin-Ca complex was characterized by FT-IR spectroscopy, scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDX) analysis as well as by means of differential scanning calorimetry (DSC). The tannin derivative stabilization efficiency under inert atmosphere was determined by using thermogravimetric analysis (TGA). In addition, its thermal stabilization effect has been assessed in air as oxidizing atmosphere by DSC in dynamic conditions. According to TGA thermograms, the initial degradation temperature (Ti) and optimum degradation temperature (Top?) for the main degradation stage of PVC stabilized with this derivative were about 280°C and 310°C, respectively. While these were about 255°C and 293°C, respectively for PVC stabilized with commercial thermal stabilizer. Global results of TGA, DSC, SEM and EDX show that the tannin-Ca complex provides the best properties and results in stabilizing both against thermal degradation and thermal oxidation degradation of PVC.

Mechanical Properties of Bio-Based Epoxy Composites Reinforced with Hybrid-Interlayer Ramie and Recycled Carbon Fibres

The growing environmental concerns have led to attention on bio-based composite materials, such as the natural fibres, recycled carbon fibres and bio-based resins. Herein, the bio-based epoxy composites were reinforced with ramie fibre (RF) and recycled carbon fibre (rCF) via inter-layer hybridisation. The dynamic mechanical analysis, tensile, flexural and impact properties characterisation were conducted to analyse the mechanical behaviour of the specimens. Also, the morphology of fractured surface after mechanical tests was studied under a scanning electron microscope. When the volume ratio between RF and rCF was varied from 100/0 to 0/100, the flexural and tensile strength of composites was significantly increased, while the impact strength was reduced. Thus the maximum values of flexural strength (182 MPa) and tensile strength (165 MPa) were observed for rCF reinforced composite, whilst impact strength of 24 kJ/m2 was found for RF reinforced composite. Furthermore, the values of storage and loss modulus were increased with the rCF incorporation due to a greater degree of restriction with the addition of rCF into the matrix. The hybridisation was able to combine the specific properties of RF and rCF and optimise the mechanical performance of composites. Therefore, the alternative low-cost green composites are prepared which can replace synthetic materials for semi-structural applications.

The Spatial and Electronic Effects of Substituent Groups on the Thermal Curing of Bio-Based Benzoxazines

To explore the influence of substituent groups on thermally induced curing,eight new bio-based benzoxazines containing different substituent groups with different electron negativity and volumes were synthesized.The thermal curing of these bio-based benzoxazines was studied in detail.Combined with the curing reaction kinetics,simulation and calculation of Highest Occupied Molecular and Lowest Unoccupied Molecular values,the spatial and electronic effects of different substituent groups on the curing of benzoxazine was explored.It was found that when the substituent was located at the position directly connected to the N atom,the steric hindrance effect of the group was dominant.When the substituent group was located on the benzene ring connected to the O atom,both the electronic effect and the spatial effect influenced the curing of benzoxazine.When an electron-withdrawing group was connected ortho position to the O atom,the curing reaction was promoted due to the decreased electron cloud density of O-on the oxazine ring,making the C-O bond easier to break.When an electron-donating group was connected to the meta position of the O atom it also promoted the curing reaction,possibly because it increased the electron cloud density of the+CH2 reaction site and thereby facilitated electrophilic substitution via attack of+CH2 on the cross linking reaction centre.This work provides a deeper understanding of how spatial and electronic effects of substituents affect the curing of benzoxazine.

Synthesis and Interfacial Properties of Bio-Based Zwitterionic Surfactants Derived from Different Fatty Acids in Non-Edible Vegetable Oils

Waste cooking oils and non-edible vegetable oils are abundant and renewable resources for bio-based materials which have showed great potential applications in many industries.In this study,five fatty acids commonly found in non-edible vegetable oils,including palmitic acid,stearic acid,linoleic acid,linolenic acid,ricinoleic acid,and their mixtures,were used to produce bio-based zwitterionic surfactants through a facile and high-yield chemical modification.These surfactants demonstrated excellent surface/interfacial properties with the minimum surface tensions ranging from 28.4 mN/m to 32.8 mN/m in aqueous solutions.The interfacial tensions between crude oil and surfactant solutions were remarkably reduced to lower values ranging from 0.0028 mN/m to 0.1983 mN/m without the aid of extra alkali,which particularly implied a great potential application in enhanced oil recovery.Meanwhile,these bio-based surfactants also showed good wetting properties(contact angles of~51°comparing with that of double distilled water,92.04°)and appropriate predicted biodegradability(degradation order of“weeks”for bio-based surfactants synthesized from saturated fatty acids,and“months”for those synthesized from unsaturated fatty acids).Bio-based surfactants synthesized from unsaturated fatty acids showed better interfacial properties in reducing interfacial tension between crude oil and formation water.The bio-based surfactants presented in this study are alternative substitutes for traditional petroleum-based surfactants in various surfactant application fields.