Enhanced mechanical performance of fused filament fabrication copolyester by continuous carbon fiber in-situ reinforcement

As one of the most commonly used thermoplastics, polyester has rarely been used as the raw materials of 3D printing. However, copolyester obtained by copolymerization modifying polyester, such as Poly Ethylene Terephthalate Glycol (PETG), has been proven to be suitable for the fused filament fabrication (FFF) technique in previous studies, but the mechanical performance of printed products is still poor. In this paper, 3D printed PETG is in-situ reinforced by continuous carbon fiber (CCF), and the relationship between the process parameters and the mechanical performance of CCF/PETG is systematically investigated. The results show that the performance of 3D printed PETG is significantly enhanced by CCF in-situ reinforcement due to the effectively impregnation of CCF. By optimizing process parameters, the tensile strength, flexural strength and flexural modulus of CCF/PETG are 597%, 293% and 650% of pure PETG, respectively, with a relatively low fiber mass fraction of 19.2 wt%. This paper demonstrates that CCF in-situ reinforced 3D printed copolyester may be used in the manufacture of complex structural parts that require high mechanical performance in the engineering application.     

Silk Fibroin as Sustainable Advanced Material: Material Properties and Characteristics,Processing, and Applications

Biobased resources are proposed as next-generation materials for advanced application. Among them, silk fibroin, a protein-based material generally obtained from Bombyx mori cocoons, is considered to play an increasing role in the development of a more sustainable generation of devices. In this review, the silk fibroin molecular structure and its original properties are presented, together with a wide overview of the available modifications and processing methods to reach custom structural and functional variations.     

Synthesis and properties of biophenol-furfural based bioresin for curing of styrene butadiene rubber

In the present work, biophenol and furfural-based resol resin was synthesized and utilized for the very first time to cure styrene butadiene rubber (SBR). The reaction was studied over a range of times, temperatures, pH, and furfural to biophenol ratios to fix the optimum conditions. Fourier transform infrared spectroscopy and nuclear magnetic resonance spectroscopy revealed the functional groups and chemical structure of the synthesized resin, respectively. An exothermic peak for the resin curing appeared at 143°C in the differential scanning calorimetry thermogram of the resin. Then, the biophenol-furfural resin was utilized for the curing of SBR. The synthesized resin increased the tensile strength of the raw rubber from 0.20 ± 0.01 MPa to 1.22 ± 0.10 MPa at 10 phr loading, and the crosslink density was 2.56 × 10⁻⁵ mol/mL. The activation energy for curing SBR containing 10 phr resin was 97 kJ/mol. The storage modulus of the resin-cured compound was improved. The glass transition temperature of the raw SBR was also shifted from −43.8 to −42.3°C when 10 phr resin was used for the curing. Hence, for the first time, this work reported the utilization of biophenol-biosourced furfural resin to cure rubbers.     

Selective hydroxyalkoxylation of epoxidized methyl oleate by an amphiphilic ionic liquid catalyst

Oleic acid is an attractive biobased platform chemical. Precursors for biobased materials can be accessed by epoxidation and subsequent hydroxyalkoxylation of oleic acid. The hydroxyalkoxylation step is conventionally performed with sulfuric acid or a metal catalyst. Due to their high polarity, many ionic liquid catalysts are ineffective for hydroxyalkoxylation of fatty acid derivatives with non-polar alcohols. In this work, we utilized an amphiphilic ionic liquid catalyst to perform hydroxyalkoxylations of epoxidized methyl oleate. An ionic liquid catalyst based on dimethyl lauryl amine was synthesized and evaluated for this reaction due to its long alkyl group. The amphiphilic nature of the ionic liquid allowed for better miscibility and reactivity compared to other ionic liquids. Several alcohols were used with high yields (≥80%) and selectivity (≥92%), including nonpolar alcohols with longer alkyl chains such as octanol and dodecanol. The high selectivity of these conditions could be advantageous for applications in lubricants, biofuels, or polyol preparation. This work demonstrates a greener alternative to conventional hydroxyalkoxylation catalysts.     

Advances in green solvents for production of polysaccharide-based packaging films: Insights of ionic liquids and deep eutectic solvents

The problems with plastic materials and the good film-forming properties of polysaccharides motivated research in the development of polysaccharide-based films. In the last 5 years, there has been an explosion of publications on using green solvents, including ionic liquids (ILs), and deep eutectic solvents (DESs) as candidates to substitute the conventional solvents/plasticizers for preparations of desired polysaccharide-based films. This review summarizes related properties and recovery of ILs and DESs, a series of green preparation strategies (including pretreatment solvents/reaction media, ILs/DESs as components, extraction solvents of bioactive compounds added into films), and inherent properties of polysaccharide-based films with/without ILs and DESs. Major reported advantages of these new solvents are high dissolving capacity of certain ILs/DESs for polysaccharides (i.e., up to 30 wt% for cellulose) and better plasticizing ability than traditional plasticizers. In addition, they frequently display intrinsic antioxidant and antibacterial activities that facilitate ILs/DESs applications in the processing of polysaccharide-based films (especially active food packaging films). ILs/DESs in the film could also be further recycled by water or ethanol/methanol treatment followed by drying/evaporation. One particularly promising approach is to use bioactive cholinium-based ILs and DESs with good safety and plasticizing ability to improve the functional properties of prepared films. Whole extracts by ILs/DESs from various byproducts can also be directly used in films without separation/polishing of compounds from the extracting agents. Scaling-up, including costs and environmental footprint, as well as the safety and applications in real foods of polysaccharide-based film with ILs/DESs (extracts) deserves more studies.     

生物基聚氨酯抗涂鸦自清洁涂料的制备及性能

以环氧大豆油和2,2-双（羟甲基）丙酸为原料，在无溶剂条件下通过开环法合成了1种高羟值生物基多元醇（ESOD）。以ESOD为羟基组分，六亚甲基二异氰酸酯三聚体为固化剂，单羟基封端聚二甲基硅氧烷（PDMS-OH）为低表面能润滑剂，制备了1种透明光滑的生物基聚氨酯抗涂鸦自清洁涂料。结果表明，只需添加1%（质量分数，下同）PDMS-OH，涂层即具有良好的抗涂鸦和自清洁性能。水、咖啡、白米醋、正十六烷、花生油液滴可在倾斜的涂层表面滑落而不留下痕迹。石墨粉、黏土粉和橙色颜料粉在倾斜的涂层表面能够被水滴轻松带走。油性记号笔在涂层表面划过时，墨水自动收缩成细小的液滴，且可用纸巾轻松擦除而不在涂层表面留下任何痕迹。涂层具有良好的耐磨性，记号笔在涂层表面涂写和擦除1 200次循环后，涂层仍具有优异的墨水收缩能力。     

Recyclability Studies on Poly(lactic acid)/Poly(butylene succinate-co-adipate) (PLA/PBSA) Biobased and Biodegradable Films

Poly(lactic acid)/poly(butylene succinate-co-adipate) (PLA/PBSA) blends are found promising for film packaging applications because of their flexibility, resistance, and compostability. Industrially extruded granules and films based on PLA and containing different amounts of PBSA are reprocessed through mini-extrusion, to simulate recycling, and tested in terms of their melt flow rate as a function of PBSA content. Moreover, pure PLA commercial granules and the film produced extruding the PLA/PBSA 60/40 blend are reprocessed several times by injection molding and characterized in terms of melt flow rate, mechanical properties, thermal properties, and color as a function of injection molding cycles. The variation in melt fluidity and thermo-mechanical properties is negligible up to 3 injection molding cycles for both pure PLA granules and PLA/PBSA blend. In the case of blend the change in color (yellowing and darkening) is more evident and slight local compositional change in injection molded items can be evidenced as well as a slight decrease in PBS crystallinity as a function of injection molding cycles. Nevertheless, in applications where these aspects are not critical, these materials can be recycled by extrusion or injection molding before being composted, thus prolonging their life cycle and storing carbon in them as longer as possible.     

Fluorine-free,highly transparent,chemically durable and low ice adhesion icephobic coatings from biobased epoxy and polydimethylsiloxane

Passive icephobic surfaces have been extensively studied by researchers due to their advantages of delaying icing time and reducing ice adhesion strength. However, icephobic materials with petroleum-based resources and toxic fluorine-containing chemicals, as one of the excellent icephobic materials, are very unfavorable for resource conservation and environmental protection. In this study, we report fluorine-free, highly transparent, chemically durable and low ice adhesion icephobic coatings prepared by glycerol triglycidyl ether (GTE) derived from natural glycerin and bis(3-aminopropyl) terminated polydimethylsiloxane (PDMS) via one-pot method. On the one hand, PDMS with multiple methyl groups and two amine groups acts as a hydrophobic modifier to modulate the surface energy of the coatings, and also acts as a structure modifier to modulate the mechanical properties of the coatings, which allow us to design and synthesis the coating with excellent deicing performance (ice adhesion strength can reach about 16 kPa). On the other hand, GTE with multiple epoxy groups works as cross-linker to endow the coatings with good cross-linked networks, so that the coatings showed good durability after being subjected to different temperature treatment and different solution treatments. In additional, the transmittance of the coating is above 91.4%, which is expected to be applied to windows and sensors.     

不同催化剂合成的聚酯、共聚酯结晶行为的研究

运用ＤＴＡ、结晶速度仪对不同催化体系合成的ＰＥＴ、ＰＥＴＡ、ＰＥＴＩ的结晶行为进行了研究。观察了Ｔｃｃ、ｔ(１／２)和ｔｉ的变化，并计算出结晶动力学常数■和Ａｖｒａｍｉ指数ｎ，就此分析了三者在成核阶段、晶粒生长阶段及整体上的结晶速度的差异，以及造成这些差异的原因。