Properties enhancement of antimicrobial chitosan-deposited polylactic acid films via cold plasma treatment

The present study aimed to understand the effect of dielectric barrier discharge cold plasma(DBD-CP)technology on the antimicrobial chitosan deposition and the properties enhancement of polylactic acid(PLA)films.The results indicated that DBD-CP was an effective method for improving the adhesion and surface hydrophilicity of PLA,facilitating the deposition of chitosan coating.This modification was attributed to the increased surface roughness,as well as the presence of polar functional groups observed through atomic force microscopy,surface free energy and Fourier transform infrared spectroscopy analysis.The study further revealed that both water resistance and mechanical properties were significantly improved after DBD-CP treatment,which was positively correlated with the amount of chitosan deposited on the PLA surfaces.Following comprehensive evaluation,the treatment at 75 W was determined as the optimal condition for enhancing the properties.Additionally,the modified film exhibited strong antimicrobial activity against Staphylococcus aureus.Consequently,the DBD-CP technology could be a promising tool for better utilization of PLA-based materials in the antibacterial food packaging industry.

3D printing of personalized polylactic acid scaffold laden with GelMA/autologous auricle cartilage to promote ear reconstruction

At present,the clinical reconstruction of the auricle usually adopts the strategy of taking autologous costal cartilage.This method has great trauma to patients,poor plasticity and inaccurate shaping.Three-dimensional(3D)printing technology has made a great breakthrough in the clinical application of orthopedic implants.This study explored the combination of 3D printing and tissue engineering to precisely reconstruct the auricle.First,a polylactic acid(PLA)polymer scaffold with a precisely customized patient appearance was fabricated,and then auricle cartilage fragments were loaded into the 3D-printed porous PLA scaffold to promote auricle reconstruction.In vitro,gelatin methacrylamide(GelMA)hydrogels loaded with different sizes of rabbit ear cartilage fragments were studied to assess the regenerative activity of various autologous cartilage fragments.In vivo,rat ear cartilage fragments were placed in an accurately designed porous PLA polymer ear scaffold to promote auricle reconstruction.The results indicated that the chondrocytes in the cartilage fragments could maintain the morphological phenotype in vitro.After three months of implantation observation,it was conducive to promoting the subsequent regeneration of cartilage in vivo.The autologous cartilage fragments combined with 3D printing technology show promising potential in auricle reconstruction.

Mechanical Property Evaluation of Glass-carbon-durian Skin Fiber Reinforced Polylactic Acid Composites

The main objective of this work was to study and develop composite materials by experiments with mixtures of synthetic(glass fiber, carbon fiber) and natural fiber(durian skin fiber) reinforcements on a polylactic acid(PLA) matrix composite, because of its excellent mechanical properties. Durian skin fiber(DSF) is a natural waste throughout Thailand, and an alternative to recycling is to realize its potential as a new reinforcement through mixing and the injection molding processes. The flexural strength(σ_(F)) and flexural modulus(E_(F)) of the composites from specimens showed a maximum value by content of durian skin fiber at 10 wt%, for good performance relative to particle dispersion between the matrix and the fiber, and showed a minimum value by content of durian skin fiber at 20 wt%, because the reinforcement material affects the mechanical properties in the experiments.

Preparation and Performance of Pueraria lobata Root Powder/Polylactic Acid Composite Films

Petroleum-based materials,such as plastic,are characterized by adverse environmental pollution;as a result,researchers have sought alternative degradable plastics that are environmentally friendly,such as polylactic acid(PLA).PLA has shown great potential to replace petroleum-based plastics.In this study,seven different samples of unmodified Pueraria lobata root powder(PRP)with different contents(i.e.,0,5,10,15,20,25,and 30 wt%)and three different modified PRPs(i.e.,treated with NaOH,NaOH-KH-550,and Formic)were used to reinforce polylactic acid(PLA)via solution casting process.These prepared PRP/PLA composite films were characterized using SEM,FTIR,UV-visible spectra analysis,TG,DSC,weight loss measurement(wt%),and mechanical measurements.The results showed that the PRP modified with KH-550(PRPK)intensified the interaction in the interface region between the PRP and the PLA matrix,thus increasing the tensile strength(54.5 MPa),elongation at break(2.8%),and Young’s modulus(3310 MPa)of the PRPK/PLA biofilms.Contact angle measurement showed that the PRP treatments contributed to the hydrophobicity of films.The transparency of PRP-10/PLA film atλ_(800)was 11.09%,and its UVA and UVB transmittance were 3.28 and 1.16,respectively.After blending PLA with PRP,the PRP/PLA composite films exhibited excellent biodegradability.In summary,PRPK improved the mechanical properties of PLA and prevented the films from ultraviolet light,suggesting that PRPK-5/PLA film could be used as packaging materials.

Biodegradation and Mechanical Property of Polylactic Acid/Thermoplastic Starch Blends with Poly (ethylene glycol)

The effects of adding poly （ethylene glycol） （PEG） into polylactic acid/thermoplastic starch blends （PLA/TPS） on the properties were investigated by DSC, SEM and mechanical property-testing. The blends of PLA/TPS blended with increasing content PEG exhibited lower temperature of glass transition （T） and lower temperature of melting （T） as well as higher melt flow index （MFI）, which indicates the plasticization and proeessability of the composites were dramatically improved. The tensile strength, flexural strength and izod impact strength of PLA/TPS （80/20） increased at first and then decreased with increasing content of PEG due to stronger interfacial adhesion. The optimized mechanical property can be obtained for the blend with 3 wt % PEG. The samples containing PEG after soil burial for 5 months showed quicker degradation being accompanied with large weight loss and mechanical properties loss.

Effects of Selected Printing Parameters on the Fire Properties of 3D-Printed Neat Polylactic Acid(PLA)and Wood/PLA Composites

The effects of selected printing parameters on the fire properties of additively produced composites from neat polylactic acid(PLA)and wood/PLA filaments were investigated.The reaction to fire of the 3D-printed specimens was tested according to the ISO 5660-1 cone calorimeter test method.The results showed that the properties of the specimens when exposed to fire were significantly affected by the incorporation of wood flour into the PLA filament.It was also interesting that PLA specimens had much better reactions to fire than the wood/PLA specimens.Time to ignition was found to be much longer in the 3D-printed PLA specimens.Although the maximal heat release rate was a little higher in the PLA than the wood/PLA specimens,the duration of HRR was longer for the wood/PLA specimens.The initial mass of the specimens was smaller in the wood/PLA composites,but during the radiant heat exposure the mass typically decreased slower than in the PLA specimens.

3D Printing of Polylactic Acid Bioplastic–Carbon Fibres and Twisted Kevlar Composites Through Coextrusion Using Fused Deposition Modeling

Polylactic acid(PLA)bioplastic is a common material used in Fused Deposition Modeling(FDM)3D printing.It is biodegradable and environmentally friendly biopolymer which made out of corn.However,it exhibits weak mechanical properties which reduced its usability as a functional prototype in a real-world application.In the present study,two PLA composites are created through coextruded with 3K carbon fibres and twisted Kevlar string(as core fibre)to form a fibre reinforced parts(FRP).The mechanical strength of printed parts was examined using ASTM D638 standard with a strain rate of 1 mm/min.It has been demonstrated that the FRPs coextruded with 3K carbon fibres had achieved significant improvement in Young’s modulus(+180.6%,9.205 GPa),ultimate tensile strength(+175.3%,103 MPa)and maximum tensile strain(+21.6%,1.833%).Although the Young’s modulus of Kevlar FRP was found to be similar to as compared to unreinforced PLA(~3.29 GPa),it has gained significant increment in terms of maximum tensile strain(+179.7%,104.64 MPa),and maximum tensile strain(+257%,5.384%).Thus,this study revealed two unique composite materials,in which the 3K carbon FRP can offer stiff and high strength structure while Kevlar FRP offers similar strength but at a higher elasticity.

Preparation and Properties of Heat Resistant Polylactic Acid(PLA)/Nano-SiO2 Composite Filament

In order to improve the thermal properties of polylactic acid（PLA） filament,nano-SiO_2 was applied to mix with PLA,then they were spun as composite filament by melt-spinning.The dispersion of nano SiO_2 and the fracture surfaces of filaments were studied by scanning electron microscopy（SEM）.The properties of composite filament,such as orientation degree,mechanical properties,and surface friction properties,were analyzed.The thermal performances of composite filament were analyzed by differential scanning calorimetry（DSC） and thermo gravimetric analysis（TGA）.The results showed that the nano-SiO_2 modified by 5% KH-550 could disperse evenly and loosely in nano-scale,and 1 wt% and 3 wt% nano-SiO_2 dispersed throughout PLA evenly.As the quantity of nano-SiO_2 increased,the properties of composite filament,such as orientation degree,friction coefficient,thermal decomposition temperature,and glass transition temperature,increased more or less.The breaking tenacity increased when 1 wt% SiO_2 was added in PLA,but declined when 3 wt% SiO_2 was added.

Preparation and Properties of Polylactic Acid( PLA) /Nano-SiO_2 Composite Master Batch with Good Thermal Properties

In order to improve the thermal properties of polylactic acid( PLA) master batch,the nano-SiO2 was applied to mixing with PLA. The structure and thermal properties of the composite master batches were studied. The results showed that the nano-SiO2 modified by 3% coupling agent KH-570 could be dispersed evenly in PLA in small scale. The thermal decomposition temperature of composite master batches increased by 6. 20-10. 80 ℃, the glass transition temperature increased by 0. 22-5. 16 ℃,and the heat enthalpy at the glass transition temperature increased by 0. 574-2. 437 J /g,compared with pure PLA. The composite master batch possessed superior thermal stability and heat resistance.

Study on Dyeing of a Novel,Pro-environment Polylactic Acid (PLA) Fiber Yarn

Seventeen disperse dyes including anthraquinone, azo, methine, nitro, and quinoline dyes were applied to dye the Polylactic Acid (PLA) yarns at different conditions, and the dyebath exhaustion was determined. The result shows that C.I. disperse red 167, C.I. disperse orange 30, and C.I. disperse blue 284 have dye-uptakes greater than 80%. Therefore, they can be used as the three principal dyes for PLA yarns. The experiment discovered that the dyes, because of their Monoazo and ester group contents, have a higher dye-uptake for the PLA fiber. The research on the optimization of dyeing techniques suggests that PLA yarn can obtain a high level of dyeing effectiveness at the following conditions: pH 4-5, dyeing temperture 110℃ for 30-40 min. Color fastness to perspiration, and water-washing fastness increased 1-1.5 by the addition of the abstergent FB during the reduction clearing.

Preparation of Nano-composites Membranes with Graphic Oxides and Polylactic Acid

Organic polymer materials were used as a layer of adhesive into the graphene sheet between the layers to enhance the interaction force between the nano-structure to achieve excellent mechanical properties and barrier properties. PLA with good flowability and easy processing was selected. The mechanical properties and barrier properties of the graphene-based composites were improved by the use of PLA for good flowability, making it easy to enter the GO layer as a binder. Three methods of preparation of GO/PLA homogeneous composite membranes were designed by vacuum filtration. The experimental results show that the injection of PLA as a molecular binder into the GO layer can effectively mimic the nano-structure, and enhance the intergranular force of the graphene molecules and the compatibility with the polymer matrix.

PLA/天然废弃植物源提取物复合材料的制备与性能

针对废弃资源综合利用和通用塑料污染问题,采用超声波辅助提取法提取天然废弃植物源有效成分,并与聚乳酸(PLA)复合,探究石榴皮提取物(PGE)和洋葱皮提取物(OPE)对PLA性能的影响。结果表明:两种提取物的加入并没有改变PLA的晶型,但提高了成核密度,减小了球晶尺寸。复合材料的热稳定性有一定的下降,但由于提取物中羟基与PLA发生了氢键作用使其下降幅度不大,同时弥补了复合材料力学性能减小的趋势。植物源提取物的添加使复合材料中的—OH基团数量增多,水蒸汽透过率也随之增大,适用于地膜及食品果蔬保鲜材料中。两种提取物赋予了复合材料不同色泽,染色成分与PLA间的界面作用使复合材料耐摩擦色牢度得以保持,扩大了其应用范围。两种复合材料具有显著的抑菌作用,其中,PGE含量为9%时,其复合材料的抗菌率可达95%以上,可以作为抗菌材料应用。

聚乳酸聚氨酯嵌段预聚体增韧PLA/TPU共混物

合成聚乳酸聚氨酯嵌段共聚物预聚体(PLA-b-PUP),以其作为聚乳酸(PLA)和热塑性聚氨酯(TPU)的活性相容剂,通过原位反应增容制备PLA/TPU/PLA-b-PUP超韧共混物.通过拉伸试验、冲击试验、SEM、FTIR、DSC和TGA研究共混物的力学性能、热性能和增韧机理.结果表明,PLA-b-PUP中的异氰酸酯基团与PLA和TPU上的活性基团发生反应,显著改善了PLA/TPU共混物两相界面的相容性.随着PLA-b-PUP的加入量增加,共混物中PLA的玻璃化转变温度和相对结晶度逐渐降低,当PLA-b-PUP的质量分数为PLA/TPU共混物的4%时,共混材料的断裂伸长率和缺口冲击强度分别达到无相容剂时的8.12和2.73倍,表现出良好的增容增韧效果.添加PLA-b-PUP后,共混物的初始分解温度有所降低,但最快分解温度有所提高.

阴茎肉膜与Buck筋膜间填充HA/PLA增粗阴茎的疗效及安全性Meta分析

目的系统评价阴茎肉膜与Buck筋膜间填充透明质酸(HA)/聚乳酸(PLA)增粗阴茎的疗效及安全性。方法计算机检索中国知网、万方数据库、中国生物医学文献数据库、PubMed和Embase数据库等,搜集国内外公开发表的有关阴茎肉膜与Buck筋膜间填充HA/PLA增粗阴茎的相关临床研究,检索时限均从建库至2022年8月,采用RevMan 5.3软件进行数据处理和荟萃分析。结果经筛选共纳入4篇文献,含275例患者。Meta分析显示,阴茎肉膜与Buck筋膜间填充HA或PLA均能明显增粗阴茎、改善阴茎外观及提升性生活满意度。相较于PLA组,HA组在阴茎增粗及提升性生活满意度方面存在优势。PLA组阴茎增粗疗效稳定,而HA组术后阴茎周长衰减趋势较明显。但两组在改善阴茎外观方面差异无统计学意义。结论阴茎肉膜与Buck筋膜间填充HA或PLA均能明显增粗阴茎、提升阴茎外观及性生活满意度,且疗效安全。与HA相比,填充PLA的疗效更稳定。

Effect of Starch/Polylactic Acid Ratio on the Interdependence of Two-Phase and the Properties of Composites

Starch/polylactic acid(PLA) composites were prepared by melt extrusion, with corn starch and PLA as raw materials, glycerol as the plasticizer. Effects of starch/PLA ratio on the interdependence of two-phase and other properties of the composites were studied. The combination of results of TGA with SEM indicated that the interdependence between starch and PLA was increased gradually as the starch/PLA ratio reduced. DSC results showed that the glass transition temperature(Tg), melting temperature(Tm) and degree of crystallinity of PLA in composites were increased gradually, whereas the cold crystallization temperature(Tc) was gradually decreased as the starch/PLA ratio reduced. The rheological properties of composites were closely related with the interdependence of two-phase, with reducing starch/PLA proportion, the interdependence was increased, and then the strain for storage modulus was firstl reduced and then gradually increased. Frequency scanning showed that the storage modulus and complex viscosity were decreased with reducing starch content. As the starch/PLA ratio reduced, the matrix phase PLA was increased, so that the strength of composites was increased gradually, whereas water absorption rate was decreased gradually.

Release performance and sustained-release efficacy of emamectin benzoate-loaded polylactic acid microspheres

High-performance liquid chromatography （HPLC） was employed to determine drug release rates based on emamectin benzoate concentrations in the medium. Release kinetics equations were used to fit the drug release behavior. The effects of particle size and release medium pH on the release rate were also investigated. The indoor toxicity of emamectin benzoate-loaded polylactic acid microspheres on the diamondback moth larva （Plutella xylostella） was studied to explore drug sustained-release performance. In acidic and neutral media, the drug release behavior of the microspheres was in accord with the first-order kinetics equation. Increasing the spray dosage of emamectin benzoate-loaded polylactic acid microspheres initially resulted in an equivalent insecticidal efficacy with the conventional emamectin benzoate microemulsion. However, the drug persistence period was four-fold longer than that observed using the conventional formulation. The developed emamectin benzoate-loaded polylactic acid microspheres showed dramatic sustained-release performance. A treatment threshold of greater than 35 mg mL-1 was established for an efficient accumulated release concentration of emamectin benzoate-loaded microspheres.

PEI@PLA气凝胶制备及其染料吸附性能研究

研究聚乳酸接枝聚乙烯亚胺气凝胶(PEI@PLA气凝胶)用于处理染料废水的效果。采用冷冻干燥法制备出具有定向通道形态的PEI@PLA气凝胶,对其外观形貌、化学组成、表面润湿性和压缩性能进行了测试,探讨了PEI@PLA气凝胶在不同温度、pH值和NaCl含量条件下与含染料废水的反应,评估了PEI@PLA气凝胶对染料的吸附效果。结果表明:PEI@PLA气凝胶具有超强的亲水性和在60%恒定应变下优异的压缩性能;PEI@PLA气凝胶对于废水中染料的吸附量随着PEI含量的增加而不断增加,气凝胶中PEI含量为210 mg,其对橙黄G(OYG)和刚果红(CR)染料的吸附能力高达(408.4±14.4)mg/g和(637.5±22.7)mg/g;吸附动力学表明,伪二阶动力学模型更适合分析PEI@PLA-150气凝胶对CR的吸附,同时,CR在气凝胶上的吸附平衡行为更符合朗格缪尔等温线模型。认为:PEI@PLA气凝胶作为染料废水吸附材料展现出优异的吸附性能。

Mechanical and Thermal Properties of Apocynum and Ramie Fiber Mat Reinforced Polylactic Acid Composites

With the increasing awareness of environmental protection and rational utilization of resources,natural fiber reinforced composites have shown broad development prospects.Apocynum fiber,known as the“king of wild fiber”,not only has moisture absorption,air permeability,and good mechanical properties but also has many health-related advantages such as antibacterial properties.In this study,four types of needle-punched Apocynum fiber and ramie fiber mat reinforced polylactic acid(PLA)composites were fabricated.Mechanical and thermal properties of the composites were tested and analyzed.The results showed that compared with those of the ramie fiber finish needle-punched mat reinforced composites,the tensile strength and the tensile modulus of Apocynum fiber finish needle-punched mat reinforced composites had increased by 15.3%and 60.1%,respectively.In comparison,the bending strength and the bending modulus were decreased by 21.8%and 7.6%,respectively.Moreover,compared with the Apocynum fiber finish needled-punched mat reinforced composites and the ramie fiber finish needle-punched mat reinforced composites,the Apocynum 50/ramie 50 finish needle-punched mat reinforced composites had the best tensile and bending properties.The after-fracture morphology was detected by a scanning electron microscope(SEM).The thermal properties of the composites were also characterized.It was found that the thermal properties of the four types of composites showed very similar behaviors.

含预制缺陷PLA蜂窝加筋结构承载力分析

目的 分析不同加筋构型及预制缺陷形式对蜂窝加筋结构抗弯承载能力的影响。方法 以热塑性PLA为基材,通过增材制造技术,制备含预制缺陷蜂窝加筋结构试件,考虑缺陷的长度、数量、深度、方向等因素,采用三点弯曲实验方式,并结合有限元仿真结果进行综合分析。结果 实验得到了结构的位移-荷载关系及破坏情况。线弹性变形阶段,实验与仿真拟合良好,该阶段内,六边构型PLA蜂窝加筋曲板结构承载能力整体优于正六边结构,但后者在后屈曲阶段的残余承载能力更好,且更不易发生断裂。相较于缺陷长度,缺陷深度和缺损肋壁数量对结构承载力的影响更为显著。缺陷方向越趋近宽度方向,结构承载能力越低。结论 实际工程中,应尽可能避免结构中间承载位置处横向加筋肋壁出现缺损,并充分利用正六边与内六边构型蜂窝加筋结构各自的承载优点。

Thermal Decomposition and Kinetics of Mixtures of Polylactic Acid and Biomass during Copyrolysis

polylactic 酸(PLA ) 的热分解面对松木头锯屑(PS ) 被学习，核桃壳(WS ) ，玉米的穗轴(CC ) 以便理解发生在废物的这些部件的 pyrolytic 行为。一个 thermogravimetric 分析器(TGA ) 被申请监视在加热下面的侧面 10 漠 ? 评估的集体损失 ? 敢瑳吗？