作者要感谢奥斯本博士愿意为卡片模板的编写提供有益的讨论和协助。

1. 共聚纤维涂层在纤维分离中的溶解作用
<ol><li>佩戴适当的化学防护手套, 以防止纤维受到污染, 从每个纱线束中切割160毫米到170毫米, 用陶瓷剪刀或新鲜的钢剃刀刀片提取。保留纱线的其余部分, 如果需要进一步分析在一个标签的容器。</li>
	<li>结或夹紧纱线的两端, 以保持纱线在浸泡在溶剂中纠缠。 注: 在本研究中, 初步探讨了从极性系列中广泛极性的溶剂。基于定性结果, 采用丙酮、水、甲醇进行了较深入的检测。最后, 以 detangling 和扫描电镜 (SEM) 结果为基础, 选用丙酮作为纤维分离的最佳溶剂。</li>
	<li>将纤维浸入2毫升至3毫升的溶剂中, 在标签培养皿中浸泡, 并盖上培养皿盖。</li>
	<li>允许纱线浸泡在丙酮中30分钟, 然后丢弃溶剂。</li>
	<li>重复步骤1.3 至 1.4, 至少增加两次, 然后允许溶剂蒸发。</li>
	<li>要去除任何丙酮残渣并协助干燥, 请将样品浸入2毫升至3毫升甲醇。</li>
	<li>允许纱线浸泡在甲醇至少30分钟。</li>
	<li>从溶剂中取出纱线, 并允许干燥至少24小时。</li>
</ol>2. 扫描电镜对涂层溶解步骤的分析
<ol><li>单独的纤维与镊子, 以前用不同的溶剂从纱束清洗, 如有必要, 在立体声显微镜下进行分析。</li>
	<li>将纤维安装在不锈钢存根 (1 厘米直径) 上, 将其用镊子粘附在双面碳带上。</li>
	<li>用导电材料 (如 Au/Pd) 将纤维涂上, 以减轻扫描电镜下的表面充电效果。</li>
	<li>将纤维样品加载到扫描电子显微镜中, 并将其成像在2伏加速电压和 50 pa-100 pa 电子电流上。在必要时应用电荷中和设置来抵消充电效果。</li>
</ol>3. 傅里叶变换红外光谱法分析涂层溶解步骤
<ol><li>切割大约30毫米到40毫米的水洗纱束。</li>
	<li>获得一张粘接红外样品卡并取下保护支承。</li>
	<li>在佩戴手套保护样品不受污染的同时, 稍微拧下纤维束, 将样品合并以进行分析, 并将样品放在卡片上的窗口上。</li>
	<li>根据制造商的规格, 准备红外光谱分析。打开清除气体, 用液氮填充检测器, 并在样品室中使用磁对准板安装 ATR 附件。</li>
	<li>在仪器软件的 "高级测量" 选项卡中, 对扫描次数和仪器分辨率的参数进行编程, 在这种情况下, 128 扫描平均分辨率为4厘米-1。</li>
	<li>用低皮棉擦拭和甲醇清洁 ATR 配件的窗户。</li>
	<li>通过按步骤3.5 中选定的参数在软件的 "基本测量" 窗口中按 "收集背景" 按钮收集背景。</li>
	<li>将光纤样本对准 ATR 附件中的窗口, 使用显微镜和视频监视器来帮助定位光纤。</li>
	<li>使用步骤3.5 中选择的参数按软件的 "基本测量" 窗口中的 "收集示例" 按钮收集样本频谱。</li>
	<li>重复步骤 3.6-3.9, 收集每样样品至少3个光谱, 直到所有样品被分析。</li>
</ol>4. 宽角度 X 射线散射法分析纤维
<ol><li>在佩戴丁腈橡胶手套时, 用剃须刀刀片从纱线线轴中切下大约25毫米纱线。</li>
	<li>将纱线的每一束集中在 25 mm 不锈钢垫圈的6.25 毫米内孔内。</li>
	<li>用玻璃纸胶带将纱线捆绑在洗衣机上。</li>
	<li>对其他两种纱线重复步骤4.1 到4.3。</li>
	<li>将包含纱线束的垫圈带到不锈钢试样夹块 (其中包含用于定位的金属棒), 如图 1所示。纤维应在垂直配置中进行分析。</li>
	<li>将银甘油控制样品安装在与垫圈相同的位置的样品夹块上。</li>
	<li>使用磁对准系统打开仪器的门, 并将试样夹块安装到分析阶段。</li>
	<li>关闭样品夹室的门, 激活真空泵, 疏散样品分析室。监视安装在仪器旁边的真空计直到真空达到约1600宾夕法尼亚州</li>
	<li>打开仪器软件, 激活光束, 并执行水平扫描, 以确定样品持有者上每个样品的 x 位置。</li>
	<li>在确定每个样本的 x 位置后, 执行垂直扫描以优化 y 位置以获得每个样本的最大信号强度。</li>
	<li>确定 x 和 y 位置后, 通过分析银色甘油控制样本来开始测量, 以确定样品和每个探测器之间的距离。</li>
	<li>使用10分钟的曝光时间分析第一个光纤样本。</li>
	<li>重复步骤 4.13, 总扫描时间为30分钟。 注意: 使用此协议, 而不是一个长的30分钟扫描案例, 因为有问题的样本暴露, 以尽量减少浪费的仪器时间。</li>
	<li>平均3扫描, 以获得最终结果使用的平均功能在适合2D 软件。</li>
	<li>对每个附加示例重复步骤 4.13-4. 15。</li>
</ol>5. 纱线解开纠结及拉伸试验准备
<ol><li>获得一个30厘米 x 30 厘米或更大的透明塑料板 (在这些实验中使用聚碳酸酯片), 可以放置在黑暗的背景, 或相同尺寸的暗塑料板。</li>
	<li>切割低粘性胶带 (大约10毫米5毫米), 并使它们可用于以下步骤。在玻璃表面上执行这一步骤, 用剃刀刀片切割胶带。</li>
	<li>胶带两端的一个20毫米规格的矩形纸模板的塑料板, 使其完全平躺。 注:20 mm 被选为这些测试的最佳测量长度根据以前的工作和可用颚分离的仪器。</li>
	<li>佩戴腈手套防止污染, 切割约70毫米至80毫米冲洗纱线, 并将其放置在玻璃滑动或其他清洁表面 (图 2a-b)。</li>
	<li>使用立体声显微镜辅助解开纠结, 用镊子小心地从纱线中取出一根纤维。在这个过程中, 注意避免损坏纤维。丢弃损坏的任何纤维 (图 2c)。</li>
	<li>将单个光纤放在纸张模板的顶部, 确保光纤与模板上的标记 (图 2d-f) 对齐。</li>
	<li>将光纤的两端都带到主板上。为了提高纤维的能见度, 在透明的塑料板下面放一个深色的背景, 或者使用黑色的塑料板。光纤应该在模板中直接放置, 并略有教学 (图 2f)。</li>
	<li>重复步骤5.3 到 5.7, 直到大约35到45纤维安装在不同的纸张模板上, 用于每种纤维。在这种情况下, 有三种类型的纤维: PBIA-co-PPTA1, PBIA 和 PBIA-co-PPTA3。</li>
	<li>一旦所有的纤维被贴在塑料板上, 添加一小滴氰胶粘剂到纤维的每个端对齐到纸模板。在拉伸测试过程中, 在纸模板的两端留出1厘米的胶水, 以便夹紧。 注: 氰被发现是最好的胶粘剂为这材料, 一个不成功的尝试与 24 h 治疗环氧树脂在代表性结果显示。</li>
	<li>在测试前, 允许粘合剂至少治疗24小时。</li>
</ol>6. 单纤维拉伸试验
<ol><li>确定测量样本的长度和延伸率, 为感兴趣的样品提供最一致的结果。这些参数可能取决于可用样本的数量和实验设置的局限性。</li>
	<li>安装拉力夹具, 校准间隙, 准备测试仪器。</li>
	<li>程序的仪器移动手柄, 以提供30毫米的缺口, 这是根据纸张模板的大小选择的测量长度, 并在每一端左侧10毫米的下巴。</li>
	<li>松开抓地面, 为加载包含单纤的纸张模板创建间隙。</li>
	<li>将步骤5中准备的一个样本移动到该仪器。使用戴手套的手, 一个小铲, 和镊子, 通过两个手柄饲料模板, 使用模板上的标记, 以协助放置。请确保胶水在手柄区域的外面。</li>
	<li>轻轻地对齐并关闭顶部抓地面, 同时仍支持光纤, 使其不向下滑动。</li>
	<li>拧紧顶部和底部螺丝与扭矩扳手, 直到螺丝只是紧。</li>
	<li>对底部螺钉重复步骤6.7。</li>
	<li>使用扭矩扳手拧紧上、下手柄上的螺钉。小心拧紧的螺丝在交叉模式, 以平衡负载的纤维。 注: 使用的适当扭矩可能不同, 必须经过实验确定。在这些实验中使用了 30 cN·m。</li>
	<li>用剪刀修剪纸模板的两面。</li>
	<li>将该仪器按0.0125 毫米/秒的恒定伸长率进行拉伸试验, 监测显示器的显示, 并在纤维破裂时停止测试。</li>
	<li>在测试结束时, 松开手柄表面, 将纤维从手柄上取下。观察断裂位置, 将破损的纤维保存在标签容器中, 进一步分析。 注意: 打破在握脸上的纤维会被从分析中丢弃, 如 ASTM D3822 中所描述的 "颚断裂"。</li>
	<li>将间隙返回到30毫米, 然后重复步骤 6.4-6.12, 直到测试完所有样品。</li>
	<li>将破碎的纤维碎片保存在模板中, 进一步进行微观分析。</li>
</ol>

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本文所用程序的完整描述要求识别某些商业产品及其供应商。这类信息的列入决不应被解释为表明这些产品或供应商是由 nist 核可的, 或者是 nist 推荐的, 或者它们一定是最好的材料、工具、软件或供应商。描述。

本文介绍的方法提供了一种替代溶剂基协议, 用于去除芳纶共聚物纤维的涂层而不使用水。前两项研究3,4显示了这种化学成分的纤维水解的证据, 接触水蒸气或液态水。在样品制备过程中避免水解, 对于下一阶段的实验是至关重要的, 因为这些纤维会因接触温暖潮湿的环境而对其老化的敏感性进行检查。
分离和安装纤维是这个实验协?...

目前, 个人保护领域的重要重点是减少为执法和军事应用个人保护所需的防弹衣的质量1。传统的装甲设计依靠的材料, 如聚苯terephthalamide (PPTA), 也称为芳纶, 聚乙烯提供保护免受弹道威胁2。然而, 有兴趣探索不同的高强度纤维材料的潜力, 以减少装甲的重量要求, 以防止特定的弹道威胁。这就导致了对芳纶共聚物纤维等替代材料的探索。这些纤维是由 [5-氨基-2 (对氨基苯基) 苯并咪唑] (amidobenzimidazole, ABI) 和对氨基苯二胺 (对 PDA) 与 terephthaloyl 氯的反应形成聚 (p苯并咪唑-terephthalamide-terephthalamide)。在这项研究中, 我们检查三种不同的纤维, 所有这些都是商业生产的材料, 从一个行业接触。一种是一种均聚纤维, 由对 ABI 与 p-二胺反应形成 5-氨基-2 (对氨基苯基) 苯并咪唑或 PBIA。本文研究的其他两种共聚物纤维预计为随机共聚物, 其 PBIA 和 PPTA 联系的比例分别为3。这些联系的相对比率不能用固态核磁共振实验来确定。这些纤维被选定作为 PBIA-co-PPTA1, PBIA-co-PPTA3 延伸在早先出版物使用的指定4。PBIA-co-PPTA3 以前没有研究过, 但有类似的结构。这些光纤系统也是最近批出的一些专利5、6、7的重点。
防弹衣的优异抗弹道性取决于所组成材料的力学性能, 如极限抗拉强度和8、9、10的应变。重要的努力11,12,13一直专注于检查的长期稳定性的聚合物纤维用于装甲通过调查这些机械性能的有害变化暴露后,环境条件。环境条件对芳纶共聚物纤维的影响在3、4的研究中一直没有受到广泛的关注。研究这些材料的一个挑战是解析纱线的测试难度。麦克唐纳4以前的工作研究了水被用来解开纱线之前进行单纤维拉伸试验的技术。然而, 对于纤维的机械强度是否因这种水暴露而改变, 没有完全的理解。解析纤维的另一种替代方法是测试纱线束的机械强度, 但是, 这需要大量的材料, 并且被认为是平均纤维在纱线束中的强度, 提供较少的具体信息。该项目的目的是研究高湿度和温度对芳纶共聚纤维力学性能的影响。因此, 有必要找到一个替代溶剂的涂层去除和纤维解开纠结, 这将使我们能够区分水解的纤维, 由于环境暴露从样品的准备。测试用单纤维的制备由于体积小而进一步复杂化。在这项工作中, 我们研究几种常见的溶剂 (水, 甲醇, 丙酮) 和选择丙酮作为最好的选择, 以制备单纤维测试。在进一步测试之前, 所有纤维都用甲醇冲洗过。采用傅里叶变换红外 (FTIR) 光谱法测定涂层的溶解和解开纠结步骤是否导致材料中的化学降解。详细的视频协议, 显示解开纠结, 化学分析和机械测试的共聚物芳纶纤维的样品准备步骤, 旨在帮助其他研究人员制定方法, 进行类似的研究实验室中的单纤维。

<table><tbody><tr><td>Stereo microscope</td><td>National</td><td>DC4-456H</td><td>Digital microscope</td></tr><tr><td>RSA-G2 Solids Analyzer</td><td>TA Instruments</td><td></td><td>Dynamic mechanical thermal analyzer used in transient tensile mode with Film Tension Clamp Accesory</td></tr><tr><td>Vertex 80</td><td>Bruker Optics</td><td></td><td>Fourier Transform Infrared spectrometer used to analyze results of washing protocol, equipped with mercury cadmium telluride (MCT) detector.</td></tr><tr><td>Durascope</td><td>Smiths Detection</td><td></td><td>Attenuated total reflectance accessory used to perform FTIR</td></tr><tr><td>Torque hex-end wrench</td><td>M.H.H. Engineering</td><td>Quickset Minor</td><td>Torque wrench</td></tr><tr><td>Methanol</td><td>J.T. Baker</td><td>9093-02</td><td>methanol solvent</td></tr><tr><td>Acetone</td><td>Fisher</td><td>A185-4</td><td>acetone solvent</td></tr><tr><td>Cyanoacrylate</td><td>Loctite</td><td></td><td>Super glue</td></tr><tr><td>FEI Helios 660 Dual Beam FIB/SEM</td><td>FEI Helios</td><td></td><td>Scanning electron microscope</td></tr><tr><td>Denton Desktop sputter coater</td><td></td><td></td><td>sputter coater</td></tr><tr><td>25 mm O.D. stainless steel washers with a 6.25 mm hole</td><td></td><td></td><td>25 mm O.D. stainless steel washers with a 6.25 mm hole</td></tr><tr><td>Silver behenate</td><td></td><td></td><td>Wide angle X-ray scattering (WAXS) standard</td></tr><tr><td>Xenocs Xeuss SAXS/WAXS small angle X-ray scattering system</td><td>Xenocs Xeuss</td><td></td><td>SAXS/WAXS small angle X-ray scattering system equipped with an X-ray video-rate imager for SAXS analysis with a minimum Q = 0.0045 &amp;Aring;-1, detector separate X-ray video-rate imager for WAXS analysis (up to about 45&amp;deg; 2&amp;theta;) sample holder chamber.</td></tr><tr><td>Fit 2D software</td><td></td><td></td><td>Software to analyze WAXS data</td></tr></tbody></table>

disentangling high strength copolymer aramid fibers to enable the determination of their mechanical properties

传统上, 软体装甲是由聚苯terephthalamide (PPTA) 和超高分子量聚乙烯制成的。然而, 为了使美国防弹衣市场的纤维选择多样化, 本文介绍了基于 5-氨基-2 (对氨基苯基) 苯并咪唑 (PBIA) 和较常规 PPTA 的共聚纤维。人们对这些纤维的长期稳定性知之甚少, 但作为凝结聚合物, 他们预计对湿气和湿度有潜在的敏感性。因此, 描述材料的强度并了解它们对环境条件的脆弱性, 对于评估其在安全应用中的使用寿命非常重要。这些纤维的弹道阻力和其他临界结构特性取决于它们的强度。为了准确确定单个纤维的强度, 有必要在不引入任何损伤的情况下将它们从纱线中解开。本文选取了三芳纶为基础的共聚物纤维。用丙酮冲洗纤维, 然后用甲醇将每个纱束中的单个纤维的有机涂层除去。这种涂层使得在不损害纤维和影响其强度的情况下, 将单个纤维从纱线束中分离出来很难进行机械测试。清洗后, 对水洗和未清洗的样品进行傅里叶变换红外光谱分析, 并对结果进行比较。实验表明, 在洗涤后, 聚 (对苯并咪唑-terephthalamide-terephthalamide) (PBIA-co-PPTA1) 和 PBIA-co-PPTA3 的光谱没有显著的变化, 而在强度为 PBIA。这表明丙酮和甲醇漂洗不会对纤维产生负面影响, 并导致化学降解。此外, 对水洗纤维进行单纤维拉伸试验, 以表征其初始抗拉强度和应变, 并与其他报告值进行比较。迭代过程的发展是必要的, 以找到一个成功的方法来执行拉伸测试这些纤维。

这里研究的共聚芳纶纤维很难从纱线束分离成单个纤维进行测试。纤维被纠缠和涂层的处理化学品, 使它们很难分离, 而不损害纤维。图 3显示了纱线内纤维的结构形态。即使是较大束的一部分, 纤维表面也显示出很大的粗糙度和泪水, 这很可能是由于对相邻纤维的强烈附着力造成的。在以前的工作由麦克唐纳4, et等, 水被用来?...

Watch this Scientific Journal Video about Disentangling High Strength Copolymer Aramid Fibers to Enable the Determination of Their Mechanical Properties at JoVE.com

Disentangling High Strength Copolymer Aramid Fibers to Enable the Determination of Their Mechanical Properties

解析高强共聚物芳纶纤维使其力学性能的测定

该研究的主要目的是制定一个协议, 以准备一致的标本, 以精确的机械测试的高强度共聚芳纶纤维, 去除涂层和解析的个别纤维链没有引入重要的化学或物理降解。

Traditionally, soft body armor has been made from poly(p-phenylene terephthalamide) (PPTA) and ultra-high molecular weight polyethylene. However, to ...

disentangling-high-strength-copolymer-aramid-fibers-to-enable

Research

JoVE Journal

Chemistry

7.1K 次观看.  National Institute of Standards and Technology. 该研究的主要目的是制定一个协议, 以准备一致的标本, 以精确的机械测试的高强度共聚芳纶纤维, 去除涂层和解析的个别纤维链没有引入重要的化学或物理降解。

视频: Disentangling High Strength Copolymer Aramid Fibers to Enable the Determination of Their Mechanical Properties

Determination of the Gas-phase Acidities of Oligopeptides

Amino acid residues located at different positions in folded proteins often exhibit different degrees of acidities. For example, a cysteine residue located at or near the N-terminus of a helix is often more acidic than that at or near the C-terminus 1-6. Although extensive experimental studies on the acid-base properties of peptides have been carried out in the condensed phase, in particular in aqueous solutions 6-8, the results are often complicated by solvent effects 7. In fact, most of the active sites in proteins are located near the interior region where solvent effects have been minimized 9,10. In order to understand intrinsic acid-base properties of peptides and proteins, it is important to perform the studies in a solvent-free environment.
We present a method to measure the acidities of oligopeptides in the gas-phase. We use a cysteine-containing oligopeptide, Ala3CysNH2 (A3CH), as the model compound. The measurements are based on the well-established extended Cooks kinetic method (Figure 1) 11-16. The experiments are carried out using a triple-quadrupole mass spectrometer interfaced with an electrospray ionization (ESI) ion source (Figure 2). For each peptide sample, several reference acids are selected. The reference acids are structurally similar organic compounds with known gas-phase acidities. A solution of the mixture of the peptide and a reference acid is introduced into the mass spectrometer, and a gas-phase proton-bound anionic cluster of peptide-reference acid is formed. The proton-bound cluster is mass isolated and subsequently fragmented via collision-induced dissociation (CID) experiments. The resulting fragment ion abundances are analyzed using a relationship between the acidities and the cluster ion dissociation kinetics. The gas-phase acidity of the peptide is then obtained by linear regression of the thermo-kinetic plots 17,18.
The method can be applied to a variety of molecular systems, including organic compounds, amino acids and their derivatives, oligonucleotides, and oligopeptides. By comparing the gas-phase acidities measured experimentally with those values calculated for different conformers, conformational effects on the acidities can be evaluated.

The determination of the gas-phase acidities of cysteine-containing oligopeptides is described. The experiments are performed using a triple quadrupole mass spectrometer. The relative acidities of the peptides are measured using collision-induced dissociation experiments, and the quantitative acidities are determined using the extended Cooks kinetic method.

寡肽测定气相酸性

Amino acid residues located at different positions in folded proteins often exhibit different degrees of acidities. For example, a cysteine residue ...

科研

化学

A Testing Platform for Durability Studies of Polymers and Fiber-reinforced Polymer Composites under Concurrent Hygrothermo-mechanical Stimuli

The durability of polymers and fiber-reinforced polymer composites under service condition is a critical aspect to be addressed for their robust designs and condition-based maintenance. These materials are adopted in a wide range of engineering applications, from aircraft and ship structures, to bridges, wind turbine blades, biomaterials and biomedical implants. Polymers are viscoelastic materials, and their response may be highly nonlinear and thus make it challenging to predict and monitor their in-service performance. The laboratory-scale testing platform presented herein assists the investigation of the influence of concurrent mechanical loadings and environmental conditions on these materials. The platform was designed to be low-cost and user-friendly. Its chemically resistant materials make the platform adaptable to studies of chemical degradation due to in-service exposure to fluids. An example of experiment was conducted at RT on closed-cell polyurethane foam samples loaded with a weight corresponding to ~50% of their ultimate static and dry load. Results show that the testing apparatus is appropriate for these studies. Results also highlight the larger vulnerability of the polymer under concurrent loading, based on the higher mid-point displacements and lower residual failure loads. Recommendations are made for additional improvements to the testing apparatus.

The durability of polymers and fiber-reinforced polymer composites in service is a critical aspect for their designs and condition-based maintenance. We present a novel low-cost laboratory testing platform for the investigation of the influence of concurrent mechanical and environmental loadings, and may help design more efficient yet safer composite structures.

一个测试平台为聚合物的耐久性研究，并在同期Hygrothermo机械刺激纤维增强聚合物复合材料

The durability of polymers and fiber-reinforced polymer composites under service condition is a critical aspect to be addressed for their robust designs ...

工程学

Environmentally-controlled Microtensile Testing of Mechanically-adaptive Polymer Nanocomposites for ex vivo Characterization

Implantable microdevices are gaining significant attention for several biomedical applications1-4. Such devices have been made from a range of materials, each offering its own advantages and shortcomings5,6. Most prominently, due to the microscale device dimensions, a high modulus is required to facilitate implantation into living tissue. Conversely, the stiffness of the device should match the surrounding tissue to minimize induced local strain7-9. Therefore, we recently developed a new class of bio-inspired materials to meet these requirements by responding to environmental stimuli with a change in mechanical properties10-14. Specifically, our poly(vinyl acetate)-based nanocomposite (PVAc-NC) displays a reduction in stiffness when exposed to water and elevated temperatures (e.g. body temperature). Unfortunately, few methods exist to quantify the stiffness of materials in vivo15, and mechanical testing outside of the physiological environment often requires large samples inappropriate for implantation. Further, stimuli-responsive materials may quickly recover their initial stiffness after explantation. Therefore, we have developed a method by which the mechanical properties of implanted microsamples can be measured ex vivo, with simulated physiological conditions maintained using moisture and temperature control13,16,17. 
To this end, a custom microtensile tester was designed to accommodate microscale samples13,17 with widely-varying Young's moduli (range of 10 MPa to 5 GPa). As our interests are in the application of PVAc-NC as a biologically-adaptable neural probe substrate, a tool capable of mechanical characterization of samples at the microscale was necessary. This tool was adapted to provide humidity and temperature control, which minimized sample drying and cooling17. As a result, the mechanical characteristics of the explanted sample closely reflect those of the sample just prior to explantation.
The overall goal of this method is to quantitatively assess the in vivo mechanical properties, specifically the Young's modulus, of stimuli-responsive, mechanically-adaptive polymer-based materials. This is accomplished by first establishing the environmental conditions that will minimize a change in sample mechanical properties after explantation without contributing to a reduction in stiffness independent of that resulting from implantation. Samples are then prepared for implantation, handling, and testing (Figure 1A). Each sample is implanted into the cerebral cortex of rats, which is represented here as an explanted rat brain, for a specified duration (Figure 1B). At this point, the sample is explanted and immediately loaded into the microtensile tester, and then subjected to tensile testing (Figure 1C). Subsequent data analysis provides insight into the mechanical behavior of these innovative materials in the environment of the cerebral cortex.

Environmentally-controlled Microtensile Testing of Mechanically-adaptive Polymer Nanocomposites for ex vivo Characterization

A method is discussed by which the in vivo mechanical behavior of stimuli-responsive materials is monitored as a function of time. Samples are tested ex vivo using a microtensile tester with environmental controls to simulate the physiological environment. This work further promotes understanding the in vivo behavior of our material.

环境控制机械自适应聚合物纳米复合材料的微拉伸测试<em&gt;体外</em&gt;表征

Implantable microdevices are gaining significant attention for several biomedical applications1-4. Such devices have been made from a range of materials, ...

生物工程

Self-assembling Morphologies Obtained from Helical Polycarbodiimide Copolymers and Their Triazole Derivatives

A facile method for the preparation of polycarbodiimide-based secondary structures (e.g., nano-rings, &#34;craters,&#34; fibers, looped fibers, fibrous networks, ribbons, worm-like aggregates, toroidal structures, and spherical particles) is described. These aggregates are morphologically influenced by extensive hydrophobic side chain-side chain interactions of the singular polycarbodiimide strands, as inferred by atomic force microscopy (AFM) and scanning electron microscopy (SEM) techniques. Polycarbodiimide-g-polystyrene copolymers (PS-PCDs) were prepared by a combination of synthetic methods, including coordination-insertion polymerization, copper(I)-catalyzed azide alkyne cycloaddition (CuAAC) &#34;click&#34; chemistry, and atom transfer radical polymerization (ATRP). PS-PCDs were found to form specific toroidal architectures at low concentrations in CHCl3. To determine the influence of a more polar solvent medium (i.e., THF and THF/EtOH) on polymer aggregation behavior, a number of representative PS-PCD composites have been tested to show discrete concentration-dependent spherical particles. These fundamental studies are of practical interest to the development of experimental procedures for desirable architectures by directed self-assembly in thin film. These architectures may be exploited as drug carriers, whereas other morphological findings represent certain interest in the area of novel functional materials.

Here, we present a protocol to prepare and visualize secondary structures (e.g., fibers, toroidal architectures, and nano-spheres) derived from helical polycarbodiimides. The morphology characterized by both atomic force microscopy (AFM) and scanning electron microscopy (SEM) was shown to depend on molecular structure, concentration, and the solvent of choice.

从螺旋聚碳化二亚胺共聚物及其三唑衍生物获得自组装形貌

A facile method for the preparation of polycarbodiimide-based secondary structures (e.g., nano-rings, &#34;craters,&#34; fibers, looped fibers, fibrous ...

Cutting Procedures, Tensile Testing, and Ageing of Flexible Unidirectional Composite Laminates

Many body armor designs incorporate unidirectional (UD) laminates. UD laminates are constructed of thin (&#60;0.05 mm) layers of high-performance yarns, where the yarns in each layer are oriented parallel to each other and held in place using binder resins and thin polymer films. The armor is constructed by stacking the unidirectional layers in different orientations. To date, only very preliminary work has been performed to characterize the ageing of the binder resins used in unidirectional laminates and the effects on their performance. For example, during the development of the conditioning protocol used in the National Institute of Justice Standard-0101.06, UD laminates showed visual signs of delamination and reductions in V50, which is the velocity at which half of the projectiles are expected to perforate the armor, after ageing. A better understanding of the material property changes in UD laminates is necessary to comprehend the long-term performance of armors constructed from these materials. There are no current standards recommended for mechanically interrogating unidirectional (UD) laminate materials. This study explores methods and best practices for accurately testing the mechanical properties of these materials and proposes a new test methodology for these materials. Best practices for ageing these materials are also described.

The goal of the study was to develop protocols to prepare consistent specimens for accurate mechanical testing of high-strength aramid or ultra-high-molar-mass polyethylene-based flexible unidirectional composite laminate materials and to describe protocols for performing artificial ageing on these materials.

柔性单向复合层压板的切割程序、拉伸测试和老化

Many body armor designs incorporate unidirectional (UD) laminates. UD laminates are constructed of thin (&#60;0.05 mm) layers of high-performance yarns, ...

Covalent Attachment of Single Molecules for AFM-based Force Spectroscopy

Atomic force microscopy (AFM)-based single molecule force spectroscopy is an ideal tool for investigating the interactions between a single polymer and surfaces. For a true single molecule experiment, covalent attachment of the probe molecule is essential because only then can hundreds of force-extension traces with one and the same single molecule be obtained. Many traces are in turn necessary to prove that a single molecule alone is probed. Additionally, passivation is crucial for preventing unwanted interactions between the single probe molecule and the AFM cantilever tip as well as between the AFM cantilever tip and the underlying surface. The functionalization protocol presented here is reliable and can easily be applied to a variety of polymers. Characteristic single molecule events (i.e., stretches and plateaus) are detected in the force-extension traces. From these events, physical parameters such as stretching force, desorption force and desorption length can be obtained. This is particularly important for the precise investigation of stimuli-responsive systems at the single molecule level. As exemplary systems poly(ethylene glycol) (PEG), poly(N-isopropylacrylamide) (PNiPAM) and polystyrene (PS) are stretched and desorbed from SiOx (for PEG and PNiPAM) and from hydrophobic self-assembled monolayer surfaces (for PS) in aqueous environment.

Covalent attachment of probe molecules to atomic force microscopy (AFM) cantilever tips is an essential technique for the investigation of their physical properties. This allows us to determine the stretching force, desorption force and length of polymers via AFM-based single molecule force spectroscopy with high reproducibility.

基于AFM的力光谱单分子共价附价

Atomic force microscopy (AFM)-based single molecule force spectroscopy is an ideal tool for investigating the interactions between a single polymer and ...

纤维复合材料层压板的制造和机械性能评估

Measuring the Mechanical Properties of Glass Fiber Reinforcement Polymer Composite Laminates Obtained by Different Fabrication Processes

The traditional wet hand lay-up process (WL) has been widely applied in the manufacturing of fiber composite laminates. However, due insufficiency in the forming pressure, the mass fraction of fiber is reduced and lots of air bubbles are trapped inside, resulting in low-quality laminates (low stiffness and strength). The wet hand lay-up/vacuum bag (WLVB) process for the fabrication of composite laminates is based on the traditional wet hand lay-up process, using a vacuum bag to remove air bubbles and provide pressure, and then carrying out the heating and curing process. 
Compared with the traditional hand lay-up process, laminates manufactured by the WLVB process show superior mechanical properties, including better strength and stiffness, higher fiber volume fraction, and lower void volume fraction, which are all benefits for composite laminates. This process is completely manual, and it is greatly influenced by the skills of the preparation personnel. Therefore, the products are prone to defects such as voids and uneven thickness, leading to unstable qualities and mechanical properties of the laminate. Hence, it is necessary to finely describe the WLVB process, finely control steps, and quantify material ratios, in order to ensure the mechanical properties of laminates. 
This paper describes the meticulous process of the WLVB process for preparing woven plain patterned glass fiber reinforcement composite laminates (GFRPs). The fiber volume content of laminates was calculated using the formula method, and the calculated results showed that the fiber volume content of WL laminates was 42.04%, while that of WLVB laminates was 57.82%, increasing by 15.78%. The mechanical properties of the laminates were characterized using tensile and impact tests. The experimental results revealed that with the WLVB process, the strength and modulus of the laminates were enhanced by 17.4% and 16.35%, respectively, and the specific absorbed energy was increased by 19.48%.

作者聚焦：使用湿法手糊/真空袋工艺提高纤维复合材料层压板质量 

This paper describes a fabrication process for fiber-reinforced polymer matrix composite laminates obtained using the wet hand lay-up/vacuum bag method.

测量通过不同制造工艺获得的玻璃纤维增强聚合物复合层压板的机械性能

The traditional wet hand lay-up process (WL) has been widely applied in the manufacturing of fiber composite laminates. However, due insufficiency in the ...

Vapor Phase Deposition of Electroactive Poly(3,4-ethylenedioxythiophene) onto Electrospun Commodity Polymer Nanofibers

This study investigates the preparation of polyacrylonitrile (PAN) nanofibers through electrospinning to create highly porous and strong materials for applications in water purification, electrocatalysis, and biomedicine. The uniformly white PAN nanofiber mats were cut into 2 cm x 2 cm coupons to ensure consistency. After electrospinning, these nanofibers were coated with an electroactive polymer (EAP) using chemical vapor deposition, with iron (III) chloride (FeCl3) serving as an oxidant for polymerizing 3,4-ethylenedioxythiophene (EDOT) into poly(3,4-ethylenedioxythiophene) (PEDOT). The study examined the impact of different FeCl3 concentrations on PEDOT deposition on the PAN coupons. PEDOT deposition led to an increase in coupon weight. Scanning electron microscopy (SEM) revealed increases in the diameter of the nanofibers treated with increasing FeCl3 oxidant concentration, although higher FeCl3&#160;concentrations caused inter-fiber bridging, implying a concomitant decrease in inter-fiber spacing. Energy dispersive X-ray spectroscopy (EDS) was used to confirm the presence of Fe, Cl, and S in the nanofibers, with sulfur content rising with FeCl3&#160;concentration used, suggesting increased PEDOT deposition efficiency with increasing oxidant concentration. Mechanical testing showed that PEDOT-coated PAN fibers had improved tensile strength and toughness in the hydrated state compared to pure PAN nanofibers. These results highlight the crucial role of FeCl3&#160;concentration in influencing the morphology and properties of PAN-PEDOT composites, enhancing their suitability for applications such as water purification, tissue engineering, biosensing, catalysis, and energy storage.

This paper describes a simple technique for coating electrospun PAN nanofibers with electroactive polymers using vapor deposition. The effects of the oxidant FeCl&#8323; on the deposition of poly(3,4-ethylenedioxythiophene) coatings on PAN were investigated to understand and optimize polymer growth, fiber diameter, and overall mechanical strength of the nanofiber mats.

电活性聚（3,4-乙烯二氧噻吩）在电纺商品聚合物纳米纤维上的气相沉积

This study investigates the preparation of polyacrylonitrile (PAN) nanofibers through electrospinning to create highly porous and strong materials for ...

解析高强共聚物芳纶纤维使其力学性能的测定

摘要

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寡肽测定气相酸性

一个测试平台为聚合物的耐久性研究，并在同期Hygrothermo机械刺激纤维增强聚合物复合材料

环境控制机械自适应聚合物纳米复合材料的微拉伸测试

从螺旋聚碳化二亚胺共聚物及其三唑衍生物获得自组装形貌

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