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.

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 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.

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.

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.

Preparation and Characterization of Raw and Chemically Modified Sponge-Gourd Fiber Reinforced Polylactic Acid Biocomposites

This research work has been undertaken to fabricate environmentally friendly biocomposites for biomedical and household applications. Sponge-gourd fibers (SGF) obtained from Luffa cylindrica plant were chemically treated separately using 5 and 10 wt% NaOH, acetic anhydride and benzoyl chloride solutions. SGF reinforced polylactic acid (PLA) biocomposites were fabricated using melt compounding technique. Surface morphological, structural, mechanical and thermal properties, as well as antibacterial activities of raw and chemically modified SGF reinforced PLA (SGF-PLA) composites were characterized by field emission scanning electron microscopy, Fourier transform infrared spectrometry, X-ray diffractometry, universal testing method, thermogravimetry, and Kirby-Bauer agar diffusion method, respectively. Surface morphology indicates that after treatment of fibers, the interfacial adhesion between PLA and fibers is improved. X-ray diffractometry result shows that chemical treatment of fibers improves the crystallinity and exhibits new chemical bond formation in the composites. After chemical treatment, compressive strength of the composites is found to increase by 10% - 35%. The thermal stability of the treated fiber reinforced composites is also found to increase significantly. The composites have no antibacterial activities and no cytotoxic effect on non-cancer cell line. Soil burial test has confirmed that the composites are biodegradable. Benzoyl chloride treatment of fibers shows superior mechanical properties and enhances thermal stability among the composites.

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.

Production of Bamboo Fiber Reinforced Fibrillated Poly(Lactic Acid)(PLA) Material Obtained by a Papermaking Process

A devised beating process was applied, which enabled the formation of slurry consisting of uniformly dispersed fibrillated polylactic acid（PLA） fibers with bamboo fiber, and the polymer material was obtained by a conventional papermaking process. Owing to the fast dewatering time, good repeatability and the facility to manufacture on a large scale, this process was used. It was revealed that the beaten PLA fiber was overall in machinery extrusion by the results of optical microscope and scanning electron microscope（SEM） observations. The improvement in the tensile index, burst index, tear index and other mechanical properties was considered as a key benefit as a result of adding bamboo fiber.

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超细纤维/非织造吸声材料的制备及性能

目前石油基多孔吸声材料在市面上被广泛应用,在环保方面仍存在一系列问题亟待解决,因此需要开发绿色可降解的多孔吸声材料。首先以聚乳酸(PLA)纤维为原料,通过针刺非织造工艺制备了PLA针刺非织造材料,考察了针刺道数、纤维喂入量、针刺深度对非织造材料结构和吸声性能的影响。结果表明,较大的纤维喂入量和适当针刺深度能够显著提升非织造材料的吸声性能,在针刺道数8道和针刺深度5mm下制备的面密度为300g/m2的针刺非织造材料(PLA300-8-5)吸声系数可达0.56。采用静电纺丝技术制备不同形貌的PLA超细纤维,并将其与PLA300-8-5非织造基材复合,构建PLA超细纤维复合吸声材料,探究了纤维形貌及超细纤维膜厚度对材料吸声性能的影响,结果表明,多孔纤维及较厚的纤维膜可以有效增强吸声性能。PLA超细纤维复合吸声材料的构建为后续新型高效吸声材料的设计开发提供一定的理论基础。

The Application of Cellulose Nanocrystals Modified with Succinic Anhydride under the Microwave Irradiation for Preparation of Polylactic Acid Nanocomposites

The aim of this work was to use cellulose nanocrystals that were obtained by hydrolysis in phosphoric acid solution and further modified with succinic anhydride in the microwave field for PLA reinforcement.A series of allbionanocomposites containing unmodified and surface modified cellulose nanocrystals with CNC content in the range of 1–3%_(w.t.) were obtained by melt blending and tested by XRD,SEM,DSC and DMA to investigate the effect of surface esterification of CNCs on the structure,morphology,dynamic mechanical properties of bionanocomposites,as well as phase transitions of PLA in the presence of cellulosic nanofiller.DMA investigations showed the highest increase of storage modulus by ca.7%(335 MPa at 25℃)in the glassy state of PLA for 2%_(w.t.)of unmodified CNC.Though,addition of 2%_(w.t.)of succinylated CNCs caused the highest increase of the onset of glass transition temperature(by 6.2℃)thus widening the temperature range of biocomposite application.The increase of glass transition temperature indicates the strongest interfacial interactions due to improved miscibility of surface modified nanocrystals and thus good dispersion of additive in PLA matrix providing high interface.

Development of Morus alba Reinforced Poly-Lactic Acid with Elevated Mechanical and Thermal Properties

This research investigates the mechanical and thermal properties of Morus alba combined with polylactic acid in comparison with other natural fibers. The study uses three different fiber and PLA compositions - 20%, 30%, and 40% respectively - to produce composite materials. In addition, another composite with the same fiber volume is treated with a 4% NaOH solution to improve mechanical properties. The composites are processed by twin-screw extrusion, granulation, and injection molding. Tensile strength measurements of raw fibers and NaOH-treated fibers were carried out using a single-fiber tensile test with a gauge length of 40 mm. It was observed that the NaOH surface treatment increases the resistance against tensile loading and exhibited improved properties for raw fiber strands. The diameter of the fibers was measured using optical microscopy. During this research, flexural tests, impact tests, differential scanning calorimetry (DSC), and heat deflection temperature measurements (HDT) were conducted to evaluate the mechanical and thermal properties of the developed composite samples. The results indicate that the mechanical properties of NaOH-treated Morus alba-reinforced polylactic acid outperform both virgin PLA samples and untreated Morus alba samples.

Preparation and Photodynamic Anti-tumor Activity of Magnetic Polylactic Acid Nanoparticles Loaded with Photosensitizer

A novel magnetic nanocarrier was strategically designed and successfully prepared.Photosensitizer 2,7,12,18-tetramethyl-3,8-di-(1-propoxyethyl)-13,17-bis-(3-hydroxypropyl)porphyrin(PHPP)was encapsulated into polylactic acid(PLA)-coated Fe3O4 nanoparticles.The diameter of nanocarrier is 30-50 nm by transmission electron micrograph(TEM).The encapsulation efficiency of photosensitizer is 27.98% calculated from UV-vis absorption spectra.The nanocarrier shows obvious photocytotoxic activity to Hela299 tumor cells in vitro.

基于3D打印技术制备CF-PLA纤维及性能研究

本文采用三维(3D)打印技术将碳纤维聚乳酸复合材料(CF-PLA)拉成纤维状,使CF-PLA纤维中的短切碳纤维呈现定向排列,从而增强CF-PLA纤维的力学性能。利用电子万能试验机对CF-PLA纤维的力学性能进行分析,并通过扫描电子显微镜观察CF-PLA纤维的微观表面形貌。试验结果表明,当打印头回抽速率为5 mm/s时,制备的CF-PLA纤维连续且均匀。通过控制打印头移动速率,制备不同直径(74~283μm)的CF-PLA纤维。随着打印头移动速率的增加,制备的CF-PLA纤维直径尺寸呈现逐渐减小的趋势。当CF-PLA纤维直径为135μm时,其拉伸强度(50 MPa)和杨氏模量(2331 MPa)均最大。此外,本文将CF-PLA纤维应用到层压板中,并研究了CF-PLA纤维体积分数对层压板力学性能的影响。研究发现,CF-PLA纤维体积分数为8%层压板的拉伸强度是CF-PLA纤维体积分数为0%层压板的2.5倍左右,其杨氏模量是CF-PLA纤维体积分数为0%层压板的2.3倍左右。

PLA/P34HB共混纤维的制备与性能

采用熔融纺丝法制备了聚乳酸(PLA)/聚(3-羟基丁酸酯-co-4-羟基丁酸酯)(P34HB)共混纤维,分析了P34HB含量对PLA/P34HB共混纤维热学性能、结晶性能和力学性能的影响,并研究了拉伸倍数对P34HB含量为30%(w)的共混纤维性能的影响。结果表明:当拉伸倍数为3倍时,随着P34HB含量的增加,PLA/P34HB共混纤维的结晶度逐渐降低,断裂强度和初始模量逐渐下降,而断裂伸长率逐渐增大;随着拉伸倍数的增大,P34HB含量为30%(w)的PLA/P34HB共混纤维的结晶度、断裂强度和初始模量逐渐提高,断裂伸长率逐渐降低,当拉伸8倍时,共混纤维的断裂强度达到425 MPa,断裂伸长率为15.5%,初始模量为7005 MPa。

焦谷氨酸改性纳米增韧剂对PLA性能的影响

本次研究通过焦谷氨酸对SiO_(2)纳米粒子增韧剂实施改性处理,并结合环氧化天然橡胶(ENR)对聚乳酸(PLA)建筑材料进行强化,进而制备出焦谷氨酸改性SiO_(2)/ENR增韧型PLA,并在此基础上对该材料的微观表面形貌和力学性能进行观察和测试。经实验研究发现,焦谷氨酸改性SiO_(2)ENR增韧型PLA中的SiO_(2)纳米粒子分散更加均匀,并且在冲击强度、弯曲强度、杨氏模量、拉伸强度等力学性能指标方面均显著优于未添加焦谷氨酸的PLA建筑材料。

PBAT/PLA复合膜结合1-MCP处理对金玉兰菜保鲜效果的影响

为研究金玉兰菜新型可降解保鲜包装及保鲜新技术,以聚苯乙烯(expanded polystyrene,EPS)泡沫箱包装作为对照,采用聚己二酸/对苯二甲酸丁二醇酯/聚乳酸[poly(butyleneadipate-co-terephthalate)/polylactic acid,PBAT/PLA]复合膜包装结合1.0μL/L 1-甲基环丙烯(1-methylcyclopropene,1-MCP)对金玉兰菜进行处理,分析测定贮藏期间[(4.0±0.5)℃],金玉兰菜呼吸强度、色差、总酚含量、多酚氧化酶活性、营养物质含量等指标的变化。结果表明,采用PBAT/PLA复合膜包装的金玉兰菜在贮藏24 d后,硬度仍保持了1.98 kg/cm^(2),感官评分平均值维持在3.425,高于对照组(1.15);PBAT/PLA+1-MCP能够延迟呼吸高峰的出现时间,并降低呼吸峰值10.72 mg CO_(2)/(kg·h),褐变指数较未添加1-MCP的处理组降低了2.3~5.7,有效抑制了营养物质的损耗。PBAT/PLA复合膜结合1-MCP处理能够有效提高金玉兰菜冷藏过程中的品质,在拓宽可降解包装材料在农产品保鲜中的应用及提高金玉兰菜保鲜技术水平方面具有潜在应用前景。

一种新型纤维素基包装材料的研制与应用设计

针对生物可降解包装材料的高成本、性能低等问题,制备一种以黄麻纤维、粘胶纤维和聚乳酸玉米纤维为主要原料的的纤维素基包装材料,并对其力学性能进行探究。结果表明,热压处理有利于增强纤维抱合性,从而增加材料的稳定性;黄麻/粘胶/玉米纤维最佳配比方案为50∶35∶15,此时,制备的复合包装材料的纵向断裂强力为212.35 N,横向断裂强力为126.78 N,纵向撕破强力为29.26 N,横向撕破强力为13.06 N,顶破强力为77.61 N。试验制备的黄麻/粘胶/玉米纤维素基包装材料不仅成本低、绿色环保,还具备较好的力学性能,能作为一种生物可降解包装材料应用于实际生活中。

聚乳酸纤维在纺织中的应用

聚乳酸来源于玉米、小麦、甜菜、木薯以及有机废弃物等原料,具有生物安全性、生物相容性、生物可降解性等特征。聚乳酸纤维的原料来源可再生,产品亲肤,废弃物可生物降解降解产物为二氧化碳和水。在实现“双碳目标”的今天,由聚乳酸制成的纤维在纺织物品中有广泛市场。通过介绍聚乳酸纤维几种加工方式,介绍聚乳酸纤维的优点,结合百姓生活中的应用案例分析,聚乳酸纤维与人们的生活息息相关,在纺织物品或其他领域中的应用比例将逐步增大,迎来一个重要的发展时期。