PLA/PEG/苎麻三元复合材料性能的研究

通过挤出共混和注塑制备了聚乳酸(PLA)/聚乙二醇(PEG)/苎麻的三元复合材料。研究结果表明:PEG的加入使得制品中苎麻纤维和PLA的取向度均有不同程度的增加。同时PEG的加入也会提高PLA的熔融结晶温度,但过高含量的PEG反而使复合物的熔融结晶温度降低。力学性能测试结果表明:PEG能够使得复合材料的韧性得到较大增强,并且随着加入量的增多,增强效果也随之变得明显。     

The effect of UV irradiation on the electrospun PCL/TiO2 composites fibers

The effect of UV irradiation and micro‐ and nano‐TiO₂ as well as titanate nanotubes (TiNT) on the phase morphology and thermal properties of the electrospun PCL composite fibers was investigated. Polycaprolactone (PCL)/TiO₂ (micro‐ and nano‐TiO₂ as well as titanate nanotubes) composite fibers were prepared by electrospinning a polymer solution. The PCL and PCL/TiO₂ composite fibers were exposed to UV light at irradiation times of 5 and 10 days. After UV irradiation the crystallinity of the electrospun PCL/TiNTcomposite fibers increased because of the large specific surface area of TiNT. The thermal stability of the PCL/TiNT electrospun composite fibers increased due to the formation of crosslinking structure after UV irradiation. The SEM analysis suggests that after UV radiation the fibers showed high degree of degradation due to the high number of fibers breakages and fibers surface voids. The results of FTIR spectroscopy confirmed that the TiO₂ particles enhance the degradation process because of their photocatalytic activity. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43539.     

Fabrication of PLA/PEG/MWCNT electrospun nanofibrous scaffolds for anticancer drug delivery

In the present study, polylactic acid (PLA)/polyethylene glycol (PEG)/multiwalled carbon nanotube (MWCNT) electrospun nanofibrous scaffolds were prepared via electrospinning process and their applications for the anticancer drug delivery system were investigated. A response surface methodology based on Box–Behnken design (BBD) was used to evaluate the effect of key parameters of electrospinning process including solution concentration, feeding rate, tip–collector distance (TCD) and applied voltage on the morphology of PLA/PEG/MWCNT nanofibrous scaffolds. In optimum conditions (concentration of 8.15%, feeding rate of 0.2 mL/h, voltage of 18.50 kV and TCD of 13.0 cm), the minimum experimental fiber diameter was found to be 225 nm which was in good agreement with the predicted value by the BBD analysis (228 nm). In vitro drug release study of doxorubicin (DOX)‐loaded nanofibrous scaffolds, higher drug content induced an extended release of drug. Also, drug release rate was not dependent on drug/polymer ratio in different electrospun nanofibrous formulations. The equation of M_t = c₀ + kt^0.5was used to describe the kinetic data of DOX release from electrospun nanofibers. The cell viability of DOX‐loaded nanofibrous scaffolds was evaluated using 3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide, a tetrazole assay on lung cancer A549 cell lines. We propose that DOX‐incorporated PLA/PEG/MWCNT nanofibrous scaffold could be used as a superior candidate for antitumor drug delivery. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41286.     

PLA/PHBV纤维的基本力学性能研究

对PLA/PHBV纤维进行了干湿断裂强力、一次定拉伸弹性、循环定拉伸弹性及松弛试验,并与纯PLA纤维进行对比来探究PLA/PHBV纤维的基本力学性能。结果表明:PLA/PHBV纤维的断裂强力和断裂伸长率较小,延展性一般,属于硬而脆的纤维;在较大形变下复合纤维表现出良好的弹性回复能力,并在经过反复拉伸后仍具备优良的弹性回复能力;相较于PLA纤维,PLA/PHBV纤维表现出良好的抗疲劳性。     

Role of Mn of PEG in the morphology and properties of electrospun PEG/CA composite fibers for thermal energy storage

As an aim toward developing novel class of form‐stable polymer‐matrix phase change materials for thermal energy storage, ultrafine composite fibers based on cellulose acetate and polyethylene glycol (PEG) with five different molecular weight (M_n) grades were prepared by electrospinning. The effects of M_n of PEG on morphology, thermal properties and mechanical properties of the composite fibers were studied by field emission scanning electron microscopy, differential scanning calorimetry, and tensile testing, respectively. It was found that the composite fibers were smooth and cylindrical shape, with the average diameters ranging from about 1000 to 1750 nm which increased with M_n of PEG. Thermal analysis results showed that the composite fibers imparted balanced thermal storage and release properties in different temperature ranges with the variation of M_n of PEG. Thermal cycling test indicated that the prepared composites had excellent thermal stability and reliability even they were subjected to 100 heating‐cooling thermal cycles. © 2009 American Institute of Chemical Engineers AIChE J, 2009     

IPDI/PEG-800扩链改性PLA的性能表征

以乳酸为原料、辛酸亚锡为催化剂,采用直接熔融缩聚法合成聚乳酸(PLA),将其用IPDI扩链,制得聚合物IPDI/PLA,再用PEG-800改性,制备出IPDI/PLEG-800。用凝胶色谱、傅里叶变换红外光谱、接触角、X射线衍射、热失重、流变学分析等手段对聚合物的结构和性能进行了表征。结果表明:与IPDI/PLA相比,IPDI/PLEG-800分子量大幅度提高,且接触角变小,亲水性能提高;IPDI/PLEG-800具有较高黏弹性;PEG-800的加入使得IPDI/PLA的结晶度提高韧,性增强。     

Effect of blend composition on the morphology development of electrospun fibres based on PAN/PMMA blends

BACKGROUND: The aim of the work presented was to determine the morphology development and relevant change in fibre diameter of a binary polymer blend system during an electrospinning process. The size of the fibre diameter is one of the important factors determining the general properties of non‐woven mats formed from electrospun fibres. RESULTS: The morphology and diameter of electrospun polyacrylonitrile (PAN)/poly(methyl methacrylate) (PMMA) blends were investigated as a function of blend ratio using scanning electron microscopy. The diameter of the electrospun PAN/PMMA fibres decreased with increasing PMMA content up to 50 wt%, and then increased again with further increase of PMMA. After thermal treatment, the fibres shrank, and an irregularly shaped morphology was observed. CONCLUSION: The electrospinning of incompatible PAN/PMMA blends leads to a microphase‐separation morphology of fibres. A phase inversion occurs at a PMMA content of between 50 and 75 wt%. Due to the phase inversion, the fibre diameter shows a minimum value at the relevant composition. Copyright © 2008 Society of Chemical Industry     

Paclitaxel-loaded PLA/PEG/fluorescein anticancer agent prepared by Ugi reaction

Two different fluorescent block copolymers of poly(lactic acid) (PLA) and polyethylene glycol (PEG) containing fluorescein grafted to the polymer chain were synthesized by Ugi four-component condensation (UFCC). The structure of these PEG–PLA copolymers was confirmed by ¹H-NMR and fluorescence spectroscopy. Paclitaxel-loaded fluorescent microspheres (PCT-FMS1 and PCT-FMS2) were prepared from them by the single-emulsion solvent evaporation method. A kinetic study of drug release in vitro using high-performance liquid chromatography showed a prolonged and controlled release of paclitaxel. Anticancer activity of release medium against colorectal cancer cell line (Caco-2) was determined using the cell viability assay. Paclitaxel-loaded microspheres were able to inhibit cancer cell growth and colony formation. The main contribution of this work is to propose a new application for UFCC in the preparation of biomasked fluorescent drug delivery systems able to improve cancer treatment.     

PET/PEG共聚酯连续熔融终缩聚过程两相稳态模型分析

针对高性能共聚酯PET/PEG缩聚过程,建立了圆盘反应器中连续熔融聚合两相稳态模型,模拟分析了缩聚反应温度、压力、停留时间以及传质系数对气相组成、共聚酯数均分子量、端羧基浓度以及副产物二甘醇和水浓度的影响。结果表明：挥发组分主要在反应器的前半部分产生,在z > 0.4后气相挥发总量已经很小;乙二醇占气相组成的比例极高,约为90%,而二甘醇的含量极低,只为0.5%左右;随反应器温度、真空度、停留时间、传质系数的增加,共聚酯产物的分子量增大,当传质系数大于0.1 s^-1后,反应器出口的共聚酯分子量几乎不再变化,此时已不受传质控制,最终产物的分子量约26000。     

电子纺丝成形及纤维形态结构研究

电子纺丝是—种可能制备具有微细直径的纤维成形技术，本文介绍了电子纺丝技术的基本原理和电子纺丝成形工艺对纤维形态结构的影响以及电子纺纤维的应用前景等。     

PLA/PEG共混材料的自增韧研究

采用压力诱导流动成型(PIF)对聚乳酸/聚乙二醇(PLA/PEG)共混物进行加工,研究了PIF对PLA/PEG共混材料的结构和性能影响.结果表明,PLA/PEG的球晶在压力作用下变形,形成无定形相和结晶相相互叠层的砖墙增韧结构,内部的分子链沿着流动方向排列;该砖墙结构使材料的拉伸性能提高了2.5倍,冲击性能提高了30倍;材料的Tg在压力诱导流动加工后升高.     

Availability of biotin incorporated in electrospun PLA fibers for streptavidin binding

Distribution of biotin at a depth of 3-10 nm from the surface of electrospun polylactic acid (PLA) fibers has been assessed by X-ray photoelectron spectroscopy (XPS) and compared to the distribution predicted by bulk calculations. Biotin concentration in the outer 3-10 nm of the fibers is greater than the predicted if biotin was distributed uniformly within the fiber. Availability of biotin for streptavidin binding at the surface of the fibers has been determined via a competitive colorimetric assay. Availability of biotin at the fiber surface was also determined to be greater than predicted by calculations assuming uniform biotin distribution. Additionally, the segregation of biotin to the exterior of the fiber increases disproportionately with increasing overall biotin concentration in the fibers. Confocal microscopy has been used to confirm capture of streptavidin, primary antibodies and fluorescence labeled secondary antibodies on PLA/biotin fibers.     

Enhanced piezoelectric properties of randomly oriented and aligned electrospun PVDF fibers by regulating the surface morphology

Harvesting energy has been attracting the attention of researchers in recent years. This work comprehensively reports the fabrication and characterization of poly(vinylidene fluoride) fiber webs with comparable diameters and diversified surface morphologies (wrinkled, smooth, and porous) based on randomly oriented and aligned fiber webs which are used as active layers to directly make a piezoelectric nanogenerator (PENG). The results show that wrinkled fibers are preferable fiber webs for the PENG owing to their outstanding properties represented by high fibers friction, supreme β phase content (F[β]), and interior pores. Furthermore, we found that the electrical outputs of the PENG based on aligned fiber webs are higher than those based on randomly oriented fiber webs due to the increase in the friction area. The electrical outputs of the PENG based on the aligned wrinkled fiber webs are able to run microelectronic devices when it subjected to a mechanical impact. We believe that our study may inspire the research area for future energy harvesting applications. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47049.     

Effect of the spin-line temperature profile on the mechanical properties of melt electrospun polyethylene fibers

The covid-19 pandemic has revealed the need for alternative production approaches with low startup costs like electrospinning for filter needs, the most imperative element of the personal protective equipment (PPE). Current attempts in advancing melt electrospinning deal with developing strategies for fiber diameter attenuation toward sub-micron scale. Here, the attunement in the spinning-zone temperature known as ''spin-line temperature profile'' was utilized as a baseline for fiber diameter reduction. The mechanical performance of the melt-electrospun linear low-density polyethylene (LLDPE) fibers is reported to characterize their structural transformation with respect to various spin-line temperature profiles. With an increase in the spin-line temperature to above 100°C in the area of cone formation, an increased tensile and yield strength along with fiber diameter reduction by four-folds was demonstrated. A significant increase in toughness, by almost three times, without compromising the stiffness and Young's modulus was observed. The dynamic mechanical analysis revealed that spinning in high temperatures produces changes in the alpha (α) relaxation, contributing to the significant increase in strain at break. These results are significant because polyolefin fibers are an imperative element of medical textiles and PPE. Therefore, developing a correlation for process-structure-properties for emerging production techniques like melt electrospinning becomes critical.     

PMMA/PEG共混物形态和热性质的研究

在聚乙二醇存在的情况下,自由基聚合得到的聚甲基丙烯酸甲酯/聚乙二醇(PMMA/PEG)共混物,是一种半结晶聚合物;有相分离发生,一部分PEG晶体依然保持其晶体的特征,另一部分PEG晶体转变成非晶态,与PMMA网络复合,形成完全均一的非晶相。     

PP/EHDPET共混体系熔体粘度对相转变的影响

以聚丙烯 (PP) /易水解聚酯 (EH DPET)共混体系为研究对象 ,测试了共混组分在不同加工温度与不同剪切速率下的熔体粘度。结果表明 ,加工温度与剪切速率的改变均会导致 PP与 EHDPET熔体粘度比的变化 ,进而影响到两组分的海 -岛结构构成。选择较高的加工温度及较低的剪切速率 ,可以使共混物 PP在高组成比时成为分散相。     

The influence of process parameters on the properties of electrospun PLLA yarns studied by the response surface methodology

Poly (l ‐lactide) (PLLA) fibrous yarns were prepared by electrospinning of polymer solutions in 2,2,2‐trifluoroethanol. Applying spinning from two oppositely charged needles the spontaneous formed triangle of fibers at a grounded substrate could be assembled into fibrous yarns using a device consisting of a take‐up roller and twister. The effect of processing parameters on the morphology, diameter and mechanical properties of PLLA yarns was investigated by the response surface methodology (RSM). This method allowed evaluating a quantitative relationship between polymer concentration, voltage, take‐up rate and distance between the needles' center and the take‐up unit on the properties of the electrospun fibers and yarns. It was found that at increasing concentrations up to 9 wt % uniform fibers were obtained with increasing mean diameters. Conversely, the fiber diameter decreased slightly when the applied voltage was increased. The take‐up rate had a significant influence on the yarn diameter, which increased as the take‐up rate decreased. The tensile strength and modulus of the yarns were correlated with these variables and it was found that the polymer concentration had the largest influence on the mechanical properties of the yarns. By applying the RSM, it was possible to obtain a relationship between processing parameters which are important in the fabrication of electrospun yarns. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41388.     

Influence of polycaprolactone/polyglycolide blended electrospun fibers on the morphology and mechanical properties of polycaprolactone

Polycaprolactone (PCL) and polyglycolide (PGA) are two biopolymers that have been used as in situ biomedical devices for various applications. The obstacle of creating a composite that captures the benefit of PCL's long degradation time, while acquiring the strength from PGA is overcoming the lack of surface adhesion between the two biopolymers for stress transfer to occur. This study investigates the use of miscible PCL‐PGA blended fibers, created by electrospinning, to increase the interfacial bonding of fibers to the PCL matrix of the polymer–polymer composite. The use of the blended fibers will thereby create the ability of load transfer from the long‐term PCL matrix to the stronger PCL‐PGA fiber reinforcement. The incorporation of the PCL‐PGA fibers was able to increase the tensile yield strength and Young's modulus over that of the bulk PCL, while decreasing the percent elongation at break. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40224.     

熔体微分电纺PLA/ATBC纳米纤维膜吸油性能

静电纺丝制备的纳米纤维孔隙率高、吸附能力强,可用于高效地处理化工行业油污染问题。聚乳酸（PLA）作为生物可降解材料,来源广泛且不会造成二次污染,具有广阔的应用前景。本文利用自制的熔体微分电纺装置,制备了PLA/乙酰基柠檬酸三丁酯（ATBC）纤维膜,探究了物料性质和增塑剂ATBC含量对PLA纤维形貌及吸油性能的影响,并获得了最佳的纺丝温度和ATBC含量。研究表明,在纺丝温度为240℃、ATBC质量分数为10%时制备的纤维直径为320nm。该纤维膜水接触角为145°,表现出良好的疏水性能,吸油倍率为138.4g/g,是市售PP无纺布吸油性能的4～5倍,保油倍率为85.8g/g。重复吸/放油5次循环后,纤维膜仍具有良好的强度而未发生断裂且可继续进行吸油,重复使用性能较好,可被应用于化工行业油污染处理。     

Solid State Viscoelastic Properties,Morphological and Melt Rheological Studies on PLA/TPU/POSS Nanocomposites

Effects of trifluoropropyl-substituted polyhedral oligomeric Silsesquioxane (POSS), on the morphological, rheological and dynamic mechanical properties of a series of poly(lactic acid)

(PLA)/thermoplastic polyurethane (TPU) blends were explored, thoroughly. Microscopic techniques including scanning electron microscope (SEM) and transmission electron microscope (TEM) utilized in conjunction with viscosity measurements to explain morphological dissimilarities between different samples. A remarkable morphological refinement was observed upon addition of POSS into the 50/50 PLA/TPU blend. This morphological change was detected by means of frequency sweep rheological experiments, where the shoulder-like plateau appears as a result of increase in the contribution from the interfacial component of elasticity in the enhancement of storage modulus. Based on the results of the dynamic time sweep small amplitude oscillatory shear (SAOS) experiments, a scaling relation was proposed to quantify the kinetics of phase separation and the associate time evolution of elasticity. It turned out that POSS particles can slow down the rate of morphological coarsening up to the 50%. Using dynamic mechanical thermal analysis (DMTA) and rheological experiments, the differences in the rate of undergoing dynamics in all the length scales, starting from segmental up to the chain level, were compared for various compositions and the discrepancies were fully described based on the dissimilarities in the entanglement densities, combinatorial effects of soft and hard segments of TPU, lubricating role of POSS particles, crystallinity, and morphological characteristics of samples.