Comparison of directly compressed vitamin B12 tablets prepared from micronized rotary-spun microfibers and cast films

Fiber-based dosage forms are potential alternatives of conventional dosage forms from the point of the improved extent and rate of drug dissolution. Rotary-spun polymer fibers and cast films were prepared and micronized in order to direct compress after homogenization with tabletting excipients. Particle size distribution of powder mixtures of micronized fibers and films homogenized with tabletting excipients were determined by laser scattering particle size distribution analyzer. Powder rheological behavior of the mixtures containing micronized fibers and cast films was also compared. Positron annihilation lifetime spectroscopy was applied for the microstructural characterization of micronized fibers and films. The water-soluble vitamin B₁₂ release from the compressed tablets was determined. It was confirmed that the rotary spinning method resulted in homogeneous supramolecularly ordered powder mixture, which was successfully compressed after homogenization with conventional tabletting excipients. The obtained directly compressed tablets showed uniform drug release of low variations. The results highlight the novel application of micronized rotary-spun fibers as intermediate for further processing reserving the original favorable powder characteristics of fibrous systems.     

PLLA/PVP共混静电纺丝形貌表征及性能研究

采用静电纺丝法制备了PLLA/PVP共混纤维膜,通过SEM、接触角表征了纤维膜的形貌以及亲水性能,同时测定了纤维膜的力学性能,探讨了共混液中PVP的比例对纤维膜形貌、亲水性能及力学性能的影响。结果表明:随着共混液中PVP比例的增大,PLLA的亲水性得到改善,但纤维的强力却迅速下降。当PVP的比例为40%和50%时,接触角接近零。SEM分析结果显示:纤维丝上孔的孔径和密度随着PVP比例的增大而发生改变。     

熔融纺丝过程优化制备细直径碳化硅纤维及其对力学性能的影响

强度、模量和柔顺性作为碳化硅(SiC)纤维重要的力学性能受到纤维直径大小的影响, 而制备工艺中的熔融纺丝过程对纤维直径起决定作用。本工作研究了纺丝温度、纺丝压力和卷绕速度对聚碳硅烷(Polycarbosilane, PCS)原纤维直径的影响, 分析了纺丝过程中纤维断裂的原因, 并初步探究了SiC纤维直径与力学性能的关系。结果表明, 在一定范围内降低纺丝温度、降低纺丝压力和提高卷绕速度均能显著减小原纤维的直径。在连续纺丝的前提下, 最优纺丝工艺下得到的PCS原纤维直径为13.5 μm。随着PCS纤维直径由18.3 μm减小至13.5 μm, SiC纤维直径则由13.8 μm减小至9.5 μm, 而SiC纤维的强度与模量分别由1.7、181 GPa提高至2.9、233 GPa, 强度分布更为集中, 柔顺性得到显著提高。     

等规聚丙烯卷绕丝的结构与性能的关系EI

研究了聚丙烯的分子量、分子量分布、纺丝温度和纺丝速度等因素对聚丙烯纤维结构和性能的影响,结果表明上述因素主要是通过卷绕丝的结构形成来影响其性能的。纤维的力学性质不能简单地通过双折射来归一化,而是与纤维的结晶形态有密切的关系,表现出相当的复杂性,次晶结构和α-晶型卷绕丝的力学性质有显著的差别。     

熔融静电纺制备超细取向纤维膜及其性能

采用熔融静电纺丝技术,利用高速滚筒制备超细取向纤维膜,以纺丝距离、纺丝电压、滚筒转速进行三因素三水平正交实验,利用扫描电子显微镜(SEM),探究各个因素对纤维取向度和纤维直径的影响,确定制备超细取向纤维膜的最优化工艺条件。同时,借助差示扫描量热仪(DSC)、拉伸实验及接触角测量仪对超细取向纤维膜的结晶性能、机械性能及疏水性进行了测试分析,并与平板接收的无序纤维膜进行对比。结果表明:当纺丝距离为10cm、纺丝电压为10kV、滚筒转速为1000r/min时,超细取向纤维表面光滑,纤维直径较小,排列紧密,具有良好的取向度,且超细取向纤维膜结晶度有所提升,水接触角变大,表现出较好的疏水性。同时,经过热压后的超细取向纤维膜机械性能明显提升。     

异型(三叶型)截面碳化硅纤维制备工艺研究

以聚碳硅烷（PCS）为原料,经不熔化和烧成制得三叶型碳化硅纤维,研究了纺丝温度,压力,收丝速度对纤维异形度和当量直径的影响,研究表明,较低的纺丝温度,适当高的纺丝压力和较低的转速有利于提高纤维的异形度,抗拉强度平均提高约30％。     

Preparation and characterization of novel gelatin/cerium (III) fiber with antibacterial activity

Gelatin/Cerium (III) fibers with high tensile strength and good antibacterial activity were prepared by wet spinning method. The fiber structure and properties were investigated. The optical microscope (OPM) results showed that the fiber had a smooth surface and the fiber diameter was in the range of 60-90 µm. The mechanical properties tests showed that the tensile strength of gelatin/cerium (III) fibers increased greatly compared with the pure gelatin fibers. Furthermore, it was found that the gelatin/Ce (III) fibers have the antibacterial activity for Escherichia coli and Staphylococcus aureus.     

高强、高模、超粗旦聚乙烯醇（PVA）纤维的研制

本文介绍了应用凝胶纺丝技术制备用于混凝土增强，力学性能很好的PVA粗旦纤维。研究了凝固浴温度、萃取条件和拉伸条件等对纤维结构和力学性能的影响，结果表明，凝胶纤维的性能与纺丝和拉伸工艺等有较大的关系。     

具备吸收雷达波功能的三叶型碳化硅纤维研制

以聚碳硅烷(PCS)为原料,采用熔融纺丝制备三叶型PCS纤维后,经不熔化和烧成制得三叶型碳化硅纤维。研究了纺丝温度、收丝速度等对纤维异形度的影响,并对预氧化和烧成工艺以及吸波性能等进行了研究。研究表明,较低的纺丝温度、适当高的纺丝压力和较低的转速有利于提高纤维的异形度。与相同当量直径的圆形纤维相比,三叶型碳化硅纤维的抗拉强度平均提高约30%,三叶型碳化硅纤维在8~18 GHz范围内具有较好的吸收雷达波性能。      

Recombinant Silk Fiber Properties Correlate to Prefibrillar Self‐Assembly

Spider silks are desirable materials with mechanical properties superior to most synthetic materials coupled with biodegradability and biocompatibility. In order to replicate natural silk properties using recombinant spider silk proteins (spidroins) and wet‐spinning methods, the focus to date has typically been on modifying protein sequence, protein size, and spinning conditions. Here, an alternative approach is demonstrated. Namely, using the same ≈57 kDa recombinant aciniform silk protein with a consistent wet‐spinning protocol, fiber mechanical properties are shown to significantly differ as a function of the solvent used to dissolve the protein at high concentration (the “spinning dope” solution). A fluorinated acid/alcohol/water dope leads to drastic improvement in fibrillar extensibility and, correspondingly, toughness compared to fibers produced using a previously developed fluorinated alcohol/water dope. To understand the underlying cause for these mechanical differences, morphology and structure of the two classes of silk fiber are compared, with features tracing back to dope‐state protein structuring and preassembly. Specifically, distinct classes of spidroin nanoparticles appear to form in each dope prior to fiber spinning and these preassembled states are, in turn, linked to fiber morphology, structure, and mechanical properties. Tailoring of dope‐state spidroin nanoparticle assembly, thus, appears a promising strategy to modulate fibrillar silk properties.     

不同晶体取向中间相沥青基带状炭纤维的制备与表征

以中间相沥青为原料, 采用不同长宽比的矩形截面喷丝板, 通过控制熔融纺丝时的收丝速率, 制得了具有不同截面尺寸和晶体取向的高定向中间相沥青基带状炭纤维, 并研究了热处理温度和喷丝孔截面尺寸对所得炭纤维结构和性能的影响。结果表明, 喷丝孔的形状和收丝速度对炭纤维的晶体取向有显著影响。当收丝速度一定时, 随着喷丝孔截面长宽比的减小, 带状炭纤维截面碳晶体层片由褶皱平行取向结构向辐射状垂直取向结构转变。随着热处理温度的升高, 所制得炭纤维的室温轴向电阻率显著减小, 热导率相应增大, 力学性能明显提高; 随着收丝速率的增大, 带状炭纤维室温轴向电阻率变化不大, 但对其力学性能有显著影响。当喷丝孔截面长宽比和纺丝速度分别为30:1和75 m/min 时, 2500℃石墨化纤维的拉伸强度和杨氏模量分别为2.53 GPa和234.77 GPa。     

Bio-inspired capillary dry spinning of regenerated silk fibroin aqueous solution

To biomimic the spinning process of silkworm or spider, a capillary spinning equipment was applied to spin regenerated silk fibroin (RSF) fibers from RSF aqueous solutions in air. This equipment exhibits a wide processing window for various RSF aqueous solutions. The effects of pH, metal ions, RSF concentration and spinning parameters on the spinnability of the spinning dope and the mechanical properties of the obtained fibers were investigated. As a result, spinning dopes with a pH from 5.2 to 6.9 have good spinnability, especially for the dope with a pH of 6.0 and a Ca²⁺ concentration of 0.3 M. The RSF concentration of this dope ranges from 44% to 48%. Under optimized conditions of our dry spinning experiments (L/D, 133; take-up speed, 30 mm/s), the obtained as-spun fiber has a breaking strength of 46 MPa, which can be improved up to 359 MPa after a preliminary post-drawing in 80 vol.% ethanol aqueous solution.     

海藻酸钠-聚乙烯醇复合纤维的研制及性能表征

海藻(SA)与聚乙烯醇(PVA)溶液共混得到不同配比的纺丝原液,通过粘度法从热动力学角度对2种高分子材料的相客性及分子间作用力进行了表征,结果表明,当m(SA)∶m(PVA)=4:1时最优,分子间作用力最强,通过长时间的静置观察,验证了该比例共混液表现出的良好相容性,并辅以红外光谱分析,再对各比例条件的共混液膜材料进行了力学性能的检测,结果表明,在该比例时膜材料具有最强的抗张强度和断裂伸长率.对SA-PVA复合纤维的湿法纺丝工艺条件进行优化,结果显示,在现有条件下,当选用30℃、pH=6.0的Ca2+凝固浴时,SA-PVA共混纺丝原液成纤性最强,并对复合纤维的吸湿性能进行了测定.     

高强度南极磷虾蛋白/海藻复合纤维的制备与表征

以戊二醛为增强改性剂,利用湿法纺丝制备含有预埋增强剂的南极磷虾蛋白/海藻（AKP/SA）初生纤维,通过初生纤维纺丝线在线热交联技术实现热交联反应从而制得高强度南极磷虾蛋白/海藻（HAKP/SA）复合纤维。利用旋转黏度计确定了增强交联反应的热交联温度,研究了交联度对复合纤维微观结构以及吸湿性能的影响,测试了增强后复合纤维力学性能和结晶性能的变化。结果表明:80℃时戊二醛能有效发生热交联反应;AKP/SA复合纤维具有较好的吸湿性能,吸湿率为7.3%,随着交联度的提高,复合纤维的吸湿性能降低,吸湿平衡时间缩短;HAKP/SA复合纤维仍以非晶形态存在,表面存在不均匀的沟槽结构;力学性能测试表明增强后的纤维断裂强度提高了13%。      

熔纺聚乙烯醇纤维对水泥砂浆的增强增韧作用

采用实验室自制的熔纺聚乙烯醇(PVA)纤维、进口凝胶纺PVA纤维和国产湿法纺PVA纤维增强增韧水泥砂浆,研究了纤维纤度和掺量对其分散性及对水泥基复合材料结构与性能的影响.结果表明,与进口凝胶纺纤维和国产湿法纺纤维相比,纤度较大的熔纺纤维在水泥砂浆中分散均匀,与水泥砂浆粘接较好,增强增韧效果好,且其纺丝工艺简便、高效、环...     

Nylon 66/poly(vinyl pyrrolidone) reinforced composites:: 1. Interphase microstructure and evaluation of fiber–matrix adhesion

Nylon 66, an aliphatic semicrystalline polyamide, was reinforced with E-glass fibers or high-modulus (AS4) carbon fibers. As in many reinforced semicrystalline thermoplastics, an interphase composed of transcrystallinity developed owing to the high nucleation density of the polymer on the fiber surface. The influence of this region on the fiber–matrix adhesion was studied with a modified microdebond test. E-glass fibers were freshly prepared in our laboratory by traditional glass-forming techniques and embedded in a film of Nylon 66 or a Nylon 66/poly(vinyl pyrrolidone) (PVP) blend. Previous work has shown that PVP, an amorphous polar polyamide, has a dramatic influence on the morphology of Nylon 66. This phenomenon was utilized to manipulate the interphase formation in the Nylon 66 composite from one having a complete transcrystalline interphase to a composite with the absence of an interphase. PVP was introduced to the matrix by solution blending with Nylon 66 and/or to the fibers as a sizing prior to embedment. The resulting morphologies were studied by polarized hot-stage optical microscopy. From the microdebond and morphology results, it was shown that the fiber–matrix adhesion in this composite system is dependent upon interphase microstructure. Composites containing transcrystallinity have higher interfacial shear strength values than those that do not contain this interphase. This has profound implications for the bulk mechanical properties of the composite, which are addressed in Part 2 of this paper.     

Biomicrofibrilar composites of high density polyethylene reinforced with curauá fibers: Mechanical,interfacial and morphological properties

Vegetal fibers are used in polymer composites to improve mechanical properties, substituting inorganic reinforcing agents produced by non renewable resources, like fiberglass. The highest performance formulation in high density polyethylene, HDPE, composites reinforced with curauá fibers were studied, aiming to improve the interphase interaction and optimize the mechanical properties. The fiber content, the type and the concentration of coupling agent were tested. The composites and the pure materials were characterized by Fourier transform infrared spectroscopy and the fiber/matrix phase adhesion was evaluated by scanning electron microscopy. The mechanical properties and the micrographs showed that the best formulation is: 20 wt.% of milled curauá fibers and 2 wt.% poly(ethylene-g-maleic anhydride). The coupled composites are also less hygroscopic than the uncoupled composites. We conclude that the composites reinforced with curauá fibers have mechanical properties comparable to commercially produced composites of HDPE reinforced with fiberglass.     

静电纺丝制备纳米纤维和纳米颗粒

利用静电纺丝方法制备聚乙烯砒咯烷酮(PVP)纳米纤维,研究了电纺溶液浓度、电压对PVP超细纤维的影响。证明了在一定范围内,纤维丝的直径随着浓度的增加越来越大,而随着电压的增加越来越小。同时制备了PVP/TiO2纳米纤维。采取高温和激光处理两种方法对复合纳米纤维进行烧结,用扫描电镜对其形貌进行表征。发现高温烧结后,TiO2颗粒发生严重的团聚。激光扫描后得到了分布均匀的TiO2颗粒,只有小部分的团聚。     

牵伸倍率对PEDOT PSS/PVA复合导电纤维结构与性能的影响

将合成的导电聚(3,4-乙撑二氧噻吩)-聚对苯乙烯磺酸(PEDOT-PSS)与聚乙烯醇(PVA)共混, 通过湿法纺丝, 得到了电导率较高、力学性能良好、可进行机织的PEDOT-PSS/PVA复合导电纤维, 研究了牵伸倍率对纤维导电性能、结构、热性能和力学性能的影响。结果表明: 随着牵伸倍率的增加, PEDOT-PSS/PVA复合导电纤维表面的微纤数量增加, 结晶性能、热稳定性及力学性能均有所提高; 当PEDOT-PSS/PVA复合导电纤维的牵伸倍率为4.0时, 其断裂强度、伸长率和初始模量分别为6.74 cN/dtex、5.95%和42.43 cN/dtex, 电导率可达到34.5 S/cm, 具有良好的应用性能。     

A novel application of electrospinning technique in sublingual membrane: characterization,permeation and in vivo study

Isosorbide dinitrate–polyvinylpyrrolidone (ISDN–PVP) electrospinning fibers were formulated and explored as potentially sublingual membrane. The addition of polyethylene glycol (PEG) to the formulation improved flexibility and reduced fluffiness of the fiber mat. The scanning electron microscopy (SEM) demonstrated that the fibers tended to be cross-linking, and the crosslinking degree increased with the increase of PEG amount. The differential scanning calorimetry (DSC) indicated that ISDN existed in non-crystalline state in the fibers (except at the highest drug content). The infrared spectroscopy suggested that ISDN had better compatibility with the ingredients owing to the hydrogen bonding (or hydrophobic interactions). The fibers were highly favorable for the fabrication of sublingual membrane due to neutral pH, large folding endurance and rapid drug release (complete dissolution within 120 s). The permeation study of ISDN through both dialysis membrane (DM) and porcine sublingual mucosa (SM) were carried out. A significant relationship of drug permeation rate through DM and SM was built up, which indicated that DM could be used to partly simulate SM and assess formulation. The pharmacokinetic study in rats demonstrated that the electrospinning fiber membrane had a higher C_max and lower T_max compared to the reference preparation, and the relative bioavailability of the fiber membrane was 151.6%.