Name: predicting catalyst extrudate breakage based on the modulus of rupture
Uploaded: 2018-05-13T13:00:00.000+00:00
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Description: Watch this Scientific Journal Video about Predicting Catalyst Extrudate Breakage Based on the Modulus of Rupture at JoVE.com

作者承认迈克尔 Pluchinsky 的帮助与高速摄影工作

使用适当的个人防护设备如安全眼镜、手套等执行本手稿中提到的任何任务。这里使用的起始材料是否, 为测量弯曲的力量, 碰撞, 长宽比或大块粉碎总挤出物从实验室研究或试验性设备研究或是商业材料获得。催化剂挤出强度取决于预处理条件, 因此对用户选择合适的处理方法是很重要的。测量结果允许从强度角度决定在进一步研究中使用哪些材料。
1. 抗弯强度
<ol><li>
弯曲强度试样制备
	<ol>
<li>浅滩的挤出样品的兴趣, 以代表性的大小为25粒子最小。使用旋转 riffler 或浅滩式采样分隔线。 注意:催化剂强度依赖于热预处理, 因此样品要求使用者在预处理方面做出一定的选择。</li>
		<li>执行以下两个典型预处理之一, 但它们的条件可能会根据用户的需要而改变。<ol>
<li>将样品煅烧538摄氏度, 1 小时。<ol>
<li>在瓷碟或耐热烧杯中放置至少25花纹催化剂挤出物。</li>
				<li>将该盘与催化剂放入一个耐火型的消音器烤箱在538°c 1 小时。</li>
				<li>煅烧后, 将热样品放入干燥, 使其冷却到环境条件。</li>
			</ol>
</li>
			<li>将样品干燥121摄氏度, 最低为2小时。<ol>
<li>在瓷碟或耐热烧杯中放置至少25花纹催化剂挤出物。</li>
				<li>将该盘与催化剂放在烘干烤箱中, 设置为121摄氏度, 最低为2小时。</li>
				<li>从烘干烤箱中取出热样品, 放入干燥, 使其冷却到环境条件下。</li>
			</ol>
</li>
		</ol>
</li>
	</ol>
</li>
	<li>
弯曲强度仪表安装 注:破裂模量的误差线为 +/-10%。根据制造商提出的程序, 每天校准设备。选择正确匹配样本形状的方法, 因为铁道部的计算取决于形状因子。<ol>
<li>启动弯曲测试框架, 并允许系统在使用前至少预热20分钟。然后打开所需的软件。</li>
		<li>根据制造商的说明附加 10 N (10 牛顿力) 负载单元。</li>
		<li>选择一个 0.2 mm/秒的铁砧速度与5毫米的支撑跨度。 注意:据观察, 对于这种速度, 催化剂不是在应变率敏感区域和断裂力是可再生的。</li>
		<li>选择 "结果" 选项卡中的 "破裂模数" 和 "最大力"。</li>
		<li>通过在框架控制台上牢牢按下 "返回" 按钮, 确保铁道部车架上的十字头处于 "零" 位置。如有必要, 可以改变十字头和铁砧的位置, 以适应不同直径的挤出物。</li>
	</ol>
</li>
	<li>
弯曲强度测量
	<ol>
<li>从干燥中抽取催化剂挤出样品, 并将其放入5-6 厘米直径的反向过滤器中, N2通过它向上吹, 形成一条干气毯。</li>
		<li>使用镊子从过滤器托盘中取一个挤出标本, 并将其放在支撑梁上。尽量减少挤出试样放置和测量的时间, 以尽量减少水分的提取。</li>
		<li>中心的催化剂挤出试样尽可能最好的左到右和前背部的支持梁</li>
		<li>单击右侧工具栏上的 "开始" 图标。 注意:在这一步, 挤出是弯曲超越了突破点, 因此测试是破坏性的, 在这个意义上。</li>
		<li>确保十字头停止, 并返回到起始位置时, 经历了40% 下降的负载力。 注意:这通常发生在挤出破损。</li>
		<li>选择右侧工具栏上的 "下一步" 图标, 继续下一个挤出。</li>
		<li>点击 "后退" 查看图表上和结果表上的数据点。</li>
		<li>在测量第二十五挤出标本后, 选择 "完成样品"。 注意:软件生成具有强度属性的报告</li>
	</ol>
</li>
</ol>2. 碰撞试验
注意:将催化剂送入滴管的进给速率保持在较低的速度, 使单个催化剂挤出物与底部的空表面发生碰撞, 而不会相互阻碍。
<ol><li>
碰撞设备准备
	<ol>
<li>将下拉管 (0.15 米直径和1.83 米长塑料管) 装配在底部的回收板 (316 SS) 上。设置进纸器放电在正确的高度选择 (这里 1.83m) 中心在下降管。改变跌落高度以改变碰撞的严重性。</li>
		<li>将振动馈线的共振频率设置为250赫兹, 电源关闭。</li>
		<li>在进料斗上放置局部通风。</li>
	</ol>
</li>
	<li>
碰撞样品准备
	<ol>
<li>浅滩的催化剂样品的兴趣, 以代表性的大小为50粒子最小。使用旋转 riffler 或浅滩式采样分隔线。</li>
		<li>轻轻筛好所制备的样品, 以避免粒径比小于或等于1的小颗粒。</li>
		<li>使用协议节3测量样本的初始纵横比。</li>
	</ol>
</li>
	<li>
碰撞催化剂下落做法
	<ol>
<li>手动将整个样品转移到进料斗。</li>
		<li>确保进纸槽出口位于下拉管的中心。</li>
		<li>打开切换开关以打开进纸器并设置为 "开始"。</li>
		<li>允许所有粒子自由地落入下拉管并撞击底板。</li>
		<li>一旦所有粒子都被喂食和丢弃, 关闭电源给馈线。</li>
		<li>从回收板中转移所有微粒, 并通过筛分轻轻地去除样品中的罚款, 以去除灰尘和碎屑。</li>
		<li>使用协议部分3测量样本的纵横比, 以完成指定1X 的第一个跌落测量。</li>
		<li>使用步骤2.3.7 的示例, 重复步骤 2.3.1 2.3.6, 并使用协议节3来测量长宽比, 以完成指定2X 的第二个跌落测量。</li>
		<li>重复上述步骤以完成多达5X 和10X 的跌落测量。 注意:你可以选择跳过中间长宽比测量, 因为长宽比在多次下落以后只改变少许。</li>
	</ol>
</li>
</ol>3. 催化剂长宽比
<ol><li>
纵横比样品准备
	<ol>
<li>浅滩的催化剂样品的兴趣, 有代表性的大小为50到250粒子。使用旋转 riffler 或浅滩式采样分隔线来获取具有代表性的样本。</li>
		<li>筛选准备好的样品, 以避免小于或等于1的小颗粒, l 代表挤出的长度, 而 D 代表挤出的直径。</li>
	</ol>
</li>
	<li>
纵横比软件与设置
	<ol>
<li>打开软件并选择屏幕顶部的 "扫描" 工具栏按钮。</li>
		<li>用超细纤维布擦拭玻璃, 除去灰尘。在扫描仪上放置一个干净的透明纸。</li>
		<li>将挤出物洒在透明度之上, 避免粒子相互接触。将粒子放在一个矩形区域内, 测量最大10厘米20厘米。</li>
		<li>在要扫描的区域内随机分布挤出物。用一双镊子将粒子相互滑动, 或者将它们放在更开阔的区域。</li>
		<li>关闭扫描仪盖。</li>
		<li>选择粒子的形状</li>
		<li>在软件设置中启用消息功能, 对于触摸粒子 (屏幕上的红色突出显示), 重叠 (或刷牙) 扫描区域边缘的粒子被自动删除, 任何具有过度曲率的粒子, 任何粒子太小 (例如尘埃斑点), 以及任何相互接触的粒子。</li>
		<li>单击 "扫描" 工具栏按钮。 注意:扫描仪将开始扫描粒子。这将需要2-3 分钟。表格结果和光学扫描图像显示在屏幕上。</li>
	</ol>
</li>
	<li>
纵横比分析
	<ol>
<li>检查扫描结果并确保扫描中包含所有合法粒子。 注意:合法的粒子有和 L/D > 1, 休息在一个自然的位置扫描和不接触其他挤出物。</li>
		<li>检查每个被怀疑接触相邻粒子的粒子, 因为计算算法不完善。</li>
		<li>消除因拥挤 (接触或躺在对方之上) 而不适当的微粒, 并在软件中消除。或者, 用镊子调整粒子的位置, 可以重新扫描整个样品。</li>
		<li>保存结果并记录以下信息: 平均直径、平均长度和粒子数。</li>
	</ol>
</li>
</ol>4. 散装粉碎试验
<ol><li>
散装粉碎样品准备
	<ol>
<li>应花纹催化剂挤出样品, 以获得总金额的合适代表。</li>
		<li>热处理的催化剂样品在538°c 至少1小时在一个消音器烤箱或类似的, 并把它热在一个干燥, 让它冷却到环境条件。</li>
	</ol>
</li>
	<li>
大块粉碎过程
	<ol>
<li>将催化剂样品容器 (杯) 装满, 用催化剂填充, 使容器中有多余的催化剂。</li>
		<li>小心水平的杯子与金属直边没有过度包装床。</li>
		<li>称量含机油的容器与一个水平的催化剂, 以获得样品的重量。</li>
		<li>将样品小心地放在负载块和活塞总成中。将负载块放在试样的顶部, 而不粉碎催化剂。</li>
		<li>将球轴承放在负载块的中心, 用小木匠的水平在滚珠轴承上均匀地调整锁臂到适当的高度。把手臂锁到位。</li>
		<li>检查压力调节器是否按用户指定的压力设置, 以应用于催化剂样品。 注意:通常情况下, 它是在 5-1, 000 帕范围, 它通常是由试验和错误的特定应用。</li>
		<li>检查负载控制阀和压力阀是否打开, 然后关闭排气阀。 注意:负载块将上升到其设定的压力。</li>
		<li>等待六十年代的样品平衡。</li>
		<li>打开排气阀, 关闭压力阀, 释放压力。观察负载块回到原来的位置。</li>
		<li>松开可调节的锁臂, 并将轴承球和负载块小心地取出。</li>
		<li>在粉碎测试后测量并记录样品的压痕。</li>
		<li>把罚款筛出来。记录所收集的罚款, 并根据协议第3条测量样品的纵横比。</li>
	</ol>
</li>
</ol>

<ol>
	<li>Le Page, J. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Applied Heterogeneous Catalysis. , (1987).</li><li>Woodcock, C. R., Mason, J. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Bulk Solids Handling: An Introduction to the Practice and Technology. , (1987).</li><li>Bertolacini, R. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mechanical+and+Physical+Testing+of+Catalysts.">Mechanical and Physical Testing of Catalysts.</a> ACS Symposium series. , 380-383 (1989).</li><li>Wu, D. F., Zhou, J. C., Li, Y. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Distribution+of+the+mechanical+strength+of+solid+catalysts.">Distribution of the mechanical strength of solid catalysts.</a> Chem Eng Res Des. 84 (12), 1152-1157 (2006).</li><li>Li, Y., Wu, D., Chang, L., Shi, Y., Wu, D., Fang, Z. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+model+for+bulk+crushing+strength+of+spherical+catalysts.">A model for bulk crushing strength of spherical catalysts.</a> Ind Eng Chem Res. 38, 1911-1916 (1999).</li><li>Li, Y., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Measurement+and+statistics+of+single+pellet+mechanical+strength+of+differently+shaped+catalysts.">Measurement and statistics of single pellet mechanical strength of differently shaped catalysts.</a> Powder Technol. 113, 176-184 (2000).</li><li>Staub, D., Meille, S., Le Corre, V., Chevalier, J., Rouleau, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Revisiting+the+side+crushing+test+using+the+three-point+bending+test+for+the+strength+measurement+of+catalyst+supports.">Revisiting the side crushing test using the three-point bending test for the strength measurement of catalyst supports.</a> Oil Gas Sci Technol. 70, 475-486 (2015).</li><li>Bridgwater, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Chapter+3,+Particle+Breakage+due+to+Bulk+Shear.">Chapter 3, Particle Breakage due to Bulk Shear.</a> Handbook of Powder Technology, 1st ed. 12, (2007).</li><li>Farsi, A., Xiang, J., Latham, J. P., Carlsson, M., Stitt, E. H., Marigo, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Does+Shape+Matter?+FEMDEM+Estimations+of+Strength+and+Post+Failure+Behaviour+of+Catalyst+Supports.">Does Shape Matter? FEMDEM Estimations of Strength and Post Failure Behaviour of Catalyst Supports.</a> 5th International Conference on Particle-Based methods. , (2017).</li><li>Beeckman, J. W. L., Fassbender, N. A., Datz, T. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Length+to+Diameter+Ratio+of+Extrudates+in+Catalyst+Technology,+I.+Modeling+Catalyst+Breakage+by+Impulsive+Forces.">Length to Diameter Ratio of Extrudates in Catalyst Technology, I. Modeling Catalyst Breakage by Impulsive Forces.</a> AIChE J. 62, 639-647 (2016).</li><li>Beeckman, J. W. L., Fassbender, N. A., Datz, T. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Length+to+Diameter+Ratio+of+Extrudates+in+Catalyst+Technology,+II.+Bending+strength+versus+Impulsive+Forces.">Length to Diameter Ratio of Extrudates in Catalyst Technology, II. Bending strength versus Impulsive Forces.</a> AIChE J. 62, 2658-2669 (2016).</li><li>Beeckman, J. W. L., Cunningham, M., Fassbender, N. A., Datz, T. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Length-to-Diameter+Ratio+of+Extrudates+in+Catalyst+Technology:+III.+Catalyst+Breakage+in+a+Fixed+Bed.">Length-to-Diameter Ratio of Extrudates in Catalyst Technology: III. Catalyst Breakage in a Fixed Bed.</a> Chem. Eng. Technol. , 1844-1851 (2017).</li></ol>

作者没有什么可透露的。

碰撞引起的冲击力断裂: 在实验室跌落试验中可以测量与表面碰撞时挤出长宽比的减小。在这个测试中, 挤出物是从一个降落伞, 下降和加速由于重力, 也经历了阻力与周围的空气。
上文概述的方法仅在文献中可用, 如 Beeckman15、16中所述。直到最近, 高度的沉闷做手工测量的卡尺为大量的挤出物可能是一个贡献的因素。暴露时间的环境空气, 因此湿度应尽量减少在测量期间和之间。如果需要, 可能需要使用 N2清除或在气缸中进行干空气清除来执行 drop 测试的协议。你也可以选择让催化剂平衡在周围空气中过夜之前, 采取任何测量, 以使水分回升较少的问题。这里使用的协议和方法有好处, 它迅速地产生长宽比为超过100-300 挤出物, 因此它采取多数可变性, 可以观察与小样品从争论。
由于形状识别软件可以错误地分配此类催化剂件的长度和直径, 因此从样品中去除长度与直径比小于统一的挤出物是很重要的。因此, 最小化和更好地消除这种短挤出物的数量也很重要。因此, 建议在测试开始时与具有足够大的纵横比的挤出物一起工作, 并限制测试的影响严重性。
对于未来的工作和从一个基本的角度来看, 这将是非常有趣的研究的碰撞, 单挤出物作为一个函数的长度, 作为一个函数的下降高度, 作为一个函数的冲击角和作为角动量的功能, 提 j只有几个变量破损时, 根据原始挤出的长度确定破裂面的位置是很有趣的。这种方法也可以适用于不挤压的材料, 而是通过挤压或球形颗粒获得的, 因此可能会应用于制药工业和食品工业。
固定床应力破坏 以上概述的方法迄今为止仅在文献中提供, 如 Beeckman18中所述。对于批量粉碎强度, 必须遵循 ASTM D7084-0417中概述的标准操作协议, 以重复性为理由。
暴露时间的环境空气, 因此湿度应尽量减少在测量期间和之间。如有必要, 该协议可能需要在手套箱中进行, 以适用于散装粉碎强度。
与碰撞情况一样, 这种方法也可以适用于不挤压的材料, 而是通过按颗粒状或通过滴水或造粒获得的球形颗粒获得的。

催化剂制造是支持石化行业和相关产业的骨干。商业催化剂, 参见 Le 页1, 典型地被挤出根据被保护的商业秘密的食谱或有专利的制造方法。典型的催化剂大小范围从1毫米到大约5毫米直径和在各种各样的形状象圆筒, trilobe 或 quadrulobe 一起也与他们的空心同行的各种各样。虽然挤出催化剂的直径和截面通常控制得很好, 但单个挤出物的长度有一个更高斯的分布, 而个体长度通常范围从大约等于一直径到几个直径。一个例外是有足够大直径的挤出催化剂, 允许它们在出口模面时被切割, 而且它们的长度分布更紧。石油化工行业典型的1毫米至3毫米直径挤出催化剂的长度分布通常是由自然破损或因其内在强度而造成的强迫破碎而获得的。
Le 页1, 伍德考克2, Bertolacini3, 吴4和 Li5显示典型的催化剂性能和复杂的强度测量。在文学和商业环境中, 典型的强度测量包括单一挤出物的平均粉碎强度和大块粉碎强度。两种强度特性都用于判断催化剂是否有足够的强度在过程中生存和使用。通常也增加磨损测试, 以判断催化剂的耐磨性在过程中。尽管在商业植物中存在着催化剂强度和使用的大型数据库, 但在公开文献中很少能获得这种信息。此外, 许多催化剂配方是临时性的, 并已建立了大量的试验和错误。对催化剂制造这方面的建模仍然是一个挑战, 至少可以说。
这里应用的是从一个三点弯曲试验中获得的欧拉-伯努利模量测量所得的催化剂的弯曲强度。Li6和凯西·斯道博7关于催化剂弯曲强度的评述但它们的工作是在相当大的直径挤出物上进行的, 没有直接应用于模型催化剂断裂。弯曲强度在文献中很少被测量和报告为典型的商业催化剂大小。此外, 在催化剂制造中, 弯曲强度往往不应用于指导。
在其制造过程中或在使用期间, 对催化剂的破损进行测量和建模是很困难的。通常, 催化剂挤出长直径比是建模的基础上的经验方法, 它与强度通过幂律, 然而, 这在许多情况下仍然有一个强大的特设组件。布里奇沃特8提供了对剪切造成的颗粒破损的全面概述, 但挤出物的长度与直径比在讨论的挤出物商业范围之外。离散元方法 (DEM) 和有限元法 (FEM) 现在也被用来研究颗粒的破损, 这些方法在一个基本水平上接近这个问题。此方法的详细信息, 请参阅 Heinrich9、Wassgren10、Potyondy11、Potapov12、卡森13和波斯语14 。本文所采用的方法和技术试图通过牛顿第二定律来帮助改进建模催化剂断裂, 以确定撞击力, 并以欧拉-伯努利模量表示的强度平衡。对于固定床的荷载应力破坏, 采用了负载力和床面弯曲强度的平衡, 从而可以预测床的纵横比作为荷载的函数。重要的是测量方法本身, 必须在良好的控制条件下应用, 这一方面是本文详细的全面。例如, 众所周知的是, 催化剂的强度受到了热处理的强烈影响, 并根据使用条件, 当催化剂可以提取水分。较高的热处理温度通常会增强催化剂的含量, 而高水分的回升通常会削弱其效果。因此, 重要的是, 强度是衡量在一个催化剂, 已经看到了适当的热处理和水分是控制在必要的地方, 以便使其代表使用的催化剂, 无论是在其制造或在使用过程中。在文献中发现的很少, 具体衡量和模型的长度到直径比的催化剂挤出物, 是典型的石化行业。最近, Beeckman15,16使用了催化剂的弯曲强度来预测由于碰撞而导致的自然断裂和催化剂的强迫断裂。这里给出了催化剂长宽比 (升/D) 的具体注意, 它定义为一个代表性样品中单个催化剂挤出物的长度与直径比值的算术平均值。本文所描述的实验方法比较简单, 可以从根本上研究和比较实验测量与理论处理。
催化剂的断裂模量是衡量其抗弯强度的一种方法。莱昂哈德·欧拉欧拉和丹尼尔伯努利开发了第一个理论上酣然的方法在断裂的弹性行为和力量在1750。图 1显示了弯曲测试和断裂力Fr的示意图。对于圆柱形挤出的具体情况, 可通过以下方法计算断裂模量:
<img alt="Equation 1" src="/files/ftp_upload/57163/57163eq1.jpg">(1)
其中, σ称为破裂模量, 并具有应力维数 (Pa)。D代表挤出的直径, 而w是两个支持点之间的距离。变量s为圆柱形因子, 等于 8/π。为全面解释在实验过程中的作用力和应力, 以及如何处理不同截面形状的参考, 给出了 Beeckman16。具体地说, σ是垂直于挤出横截面的断裂的拉伸应力, 位于两个支撑点中间的极光纤中。
对于挤出与曲面的冲突, Beeckman15显示了关于挤出纵横比的两个渐近线。在多次重复的影响下, 第一个称为Φ∞的渐近线被到达。这种渐近行为很容易理解, 因为在碰撞后断裂后, 较短的催化剂动量较小, 因此在撞击过程中的作用力较小。同时, 较短的催化剂也需要更多的力从扭矩的角度来打破, 因此, 在许多影响下, 催化剂有望达到渐近长宽比Φ∞ 。当丢弃的挤出物时间足够长时, 第二个称为Φα的渐近线在一次撞击后到达. 长挤出物有比例更高的动量和断裂在几个地方沿他们的长度的第一个冲击和纵横比后碰撞到达第二个渐近线指定的Φα. 两个渐近线都可以通过回归的碰撞数据来发现, 测量长宽比作为重复撞击次数的函数:
<img alt="Equation 2" src="/files/ftp_upload/57163/57163eq2.jpg">(2)
其中Φ0是初始长宽比, Φj 是j下降后的长宽比。参数Φ∞和Φα 都具有物理机械意义, 这与影响的严重性和催化剂的强度有关。撞击的严重性可以通过改变跌落高度来改变, 尽管对于大的跌落高度, 催化剂接近终点速度, 因此严重程度会降低。
颗粒长度和粒径是催化剂在生产和使用过程中的重要特性。催化剂颗粒的大小和形状也是决定其填料特性的因素, 影响催化剂床的压降。在早期, 这些属性通常是手工测量的, 这是一个非常繁琐的过程。现在, 这些性能可以很容易获得的第一次光学扫描一个大样本的催化剂挤出物。然后, 用成像软件确定单个粒子的大小。这样可以快速准确地分析大量的粒子, 请参见 Beeckman15。这些系统被调整, 以有效地识别和测量直径在0.8 到4.0 毫米范围内的粒子, 长度可以是几个直径长。此方法使用催化剂的 "自上而下" 视图, 从而产生 "光" 直径。对于某些形状, 在将光学直径与用卡尺手动确定的直径值进行比较时, 必须注意。
催化剂和催化剂载体的大块粉碎强度试验, ASTM D7084-0417在这里使用的是公认的标准测试方法。催化剂是加载在圆柱细胞和压力 (压力) 通常适用于 5-1, 000 帕范围内, 并允许平衡。在每个压力点之后, 催化剂被卸载。催化剂的细度从催化剂样品中筛选出来, 在催化剂样品的大部分花纹, 以获得具有代表性的样品以精确测量长宽比。虽然标准散装粉碎强度试验程序集中为衡量催化剂强度而创建的罚款量, 这篇手稿集中在削减的纵横比后, 破碎作为负载的功能, 也请参见 Beeckman18.

<table><tbody><tr><td>Modulus of rupture (MOR)</td><td>INSTRON</td><td>MODEL 5942 SINGLE COLUMN TABLE TOP</td><td></td></tr><tr><td>Modulus of rupture (MOR)</td><td>INSTRON</td><td>10 NEWTON LOAD CELL</td><td></td></tr><tr><td>Modulus of rupture (MOR)</td><td>INSTRON</td><td>50 NEWTON LOAD CELL</td><td></td></tr><tr><td>Modulus of rupture (MOR)</td><td>INSTRON</td><td>BLEUHILL 3 SOFTWARE</td><td></td></tr><tr><td>Filter</td><td>VWR</td><td>BUCHNER FILTER</td><td></td></tr><tr><td>Aspect ratio (avg L/D)</td><td>EPSON</td><td>PERFECTION V700 PHOTO INSTRUMENT</td><td></td></tr><tr><td>Software</td><td>CASCADE DATA SYSTEMS</td><td>ALIAS 3-4 SOFTWARE</td><td></td></tr><tr><td>Riffling</td><td>HUMBOLDT MFG. Co</td><td>SPINNING RIFFLER</td><td></td></tr><tr><td>Riffling</td><td>HUMBOLDT MFG. Co</td><td>RIFFLE -TYPE SAMPLE DIVIDER</td><td></td></tr><tr><td>Sieve screen</td><td>VWR</td><td>US MESH SIEVE SCREEN, # 16</td><td></td></tr></tbody></table>

predicting catalyst extrudate breakage based on the modulus of rupture

挤压催化剂的机械强度及其在固定床上的碰撞对表面或受压载荷的自然或强迫断裂是催化剂技术中的重要现象。以其弯曲强度或弯曲强度来测量催化剂的机械强度。该技术在应用于工业用典型尺寸的商用催化剂方面相对较新。在挤出物通过垂直管道中的环境空气后, 对表面碰撞后的催化剂破损进行测量。运用牛顿第二定律, 从理论上对冲击力进行量化。根据散装粉碎强度试验的标准程序, 对固定床内应力引起的催化剂破损进行了测量。这里的小说重点是测量挤出物的长度和直径比的减少作为应力的函数。

碰撞破坏: 为了给读者一个关于挤出对表面影响的复杂性的想法, 人们认为提供一些快照图片是有益的, 在当时我们已经有了最高的帧速度 (1万帧/秒)。图 2显示了这种高速摄影, 并捕获了单个挤出物在影响聚碳酸酯表面时的破损。这个表面有额外的优势, 它显示了挤出的方法之前, 反射率的影响, 从表面上, 并允许明确定义的接触实例。受影响的破损持续时间似乎小于 10-4 , 而完全影响历史记录显示为非常复杂。在碰撞过程中, 挤出作为时间函数所经历的力量是非常尖锐和不规则的。平均减速定义为撞击速度超过接触时间只是一个粗略的估计发生了什么。当乘以挤出的质量它再是力量的仅粗略的估计。
在25种不同的催化剂上确定了渐近长宽比Φ∞ , 并在 Beeckman16中给出了它们的性质。使用 Eq 进行非线性回归, 得到了每个催化剂的模型参数Φ∞ . (2) 介绍中所示。
图 3显示了同一催化剂批次中多次从不同高度跌落的典型新鲜催化剂的纵横比的降低。此序列清楚地显示了向渐近纵横比的行外, Φ∞为不同的降高度i. e。不同的严重性。Beeckman16表明, 在秋季, 由于环境空气的阻力减慢了挤出物的加速度, 最终达到了大落差的终点速度, 大跌落高度的纵横比差异变得越来越小。高度。研究还表明, 挤出物遵循二阶断裂定律, 解释了纵横比趋势曲线的形状与连续滴数的变化规律。图 4显示了与图 3中相同的催化剂的纵横比, 但现在从一个单一的影响 (每个数据点都是从一个挤出生成) 开始使用非常长的选择催化剂链。实体符号表示每组大小的纵横比的平均值。这显示了第二个渐近线Φα的存在, 以及当长度与直径比率从非常有限的挤出物中获得时所涉及的误差线的欣赏。
在碰撞过程中挤出的脉冲力可以通过牛顿第二定律来发现。结果表明, 在渐近长宽比Φ∞中, 将断裂力等同于脉冲力会导致以下相关性:
<img alt="Equation 3" src="/files/ftp_upload/57163/57163eq3.jpg">(3)
由以下所给出的归一化无量纲群:
<img alt="Equation 4" src="/files/ftp_upload/57163/57163eq4.jpg">(4)
其中σ、Ψ、 p、 D和g分别为断裂的催化剂模量、催化剂形状因子、催化剂密度、催化剂直径和重力加速度。影响S∞的规范化无量纲严重性可以表示为:
<img alt="Equation 5" src="/files/ftp_upload/57163/57163eq5.jpg">(5)
v的撞击速度在哪里, Δt是碰撞的持续时间, C是碰撞交互因子。进一步表明, 对于总共25种不同尺寸、形状和化学组成的催化剂, 在跌落试验中, 在第一近似下测试, 组实质上是一个常量. <img alt="Equation 5b" src="/files/ftp_upload/57163/57163eq5b.jpg">
固定床应力破坏: 对表 1中显示的五催化剂进行了各种压力下的大块粉碎试验研究。在一定的压力下, 这里称为临界压力, 在床的催化剂长宽比上没有发生根本性的变化。一旦压力增加到这个临界值之上, 催化剂挤出开始分解, 并且床的纵横比自然地调整, 直到床的弯曲的力量再能承受应用的重音。实验结果和预测结果的比较示例显示在图 5中。预测值将显示为实曲线, 并从挤出物催化剂的起始长宽比Φ0开始获得, 直到到达临界压力 P c 为止. 此后, 纵横比的值随荷载压力的负一第三幂减小。
找到一张床承受催化剂破损的最大允许载荷的方法是, 在破裂时利用负载力与催化剂床强度的平衡。
Beeckman18表明, 与负载力平衡的催化剂的纵横比可以用以下描述:
<img alt="Equation 6" src="/files/ftp_upload/57163/57163eq6.jpg">(6)
其中Φ是挤出长宽比, 而是r 是由以下内容提供的无量纲组:
<img alt="Equation 7" src="/files/ftp_upload/57163/57163eq7.jpg">(7)
如果σ是破裂的模量, 则s与碰撞时的挤出形状因子相同, 而P是应力。Ψ的值由床填料和床粒到颗粒力相互作用确定, 作者给出了 61/6或大约1.35 Ψ的理论值。
综上所述, 如果在大粉碎强度测试中加载了挤出物床, 并且应用了应力 p, 则挤出物将在应用 应力P 下的整个床上断裂, 以 Eq 给出平均值. (6)。因此, 具有起始长宽比Φ0的床具有临界压力Pc 它可以承受的:
<img alt="Equation 8" src="/files/ftp_upload/57163/57163eq8.jpg">(8)
<table fo:keep-together.within-page="1"><tbody>
<tr>
<td>催化剂</td>
			<td>形状</td>
			<td>D、直径</td>
			<td>Φ0 , 初始长宽比</td>
			<td>s, 形状因素</td>
			<td>ρ, 密度</td>
			<td>σ</td>
			<td>Pc, 临界应力</td>
		</tr>
<tr>
<td></td>
			<td></td>
			<td>m</td>
			<td>(-)</td>
			<td>(-)</td>
			<td>魔芋-3
</td>
			<td>M p a</td>
			<td>Kpa</td>
		</tr>
<tr>
<td>一个</td>
			<td>QUADRULOBE</td>
			<td>1.43E-03</td>
			<td>3.18</td>
			<td>2.20</td>
			<td>1250</td>
			<td>0.81</td>
			<td>27。9</td>
		</tr>
<tr>
<td>B</td>
			<td>缸</td>
			<td>9.50E-04</td>
			<td>5.92</td>
			<td>2.55</td>
			<td>750</td>
			<td>1.38</td>
			<td>6。4</td>
		</tr>
<tr>
<td>C</td>
			<td>缸</td>
			<td>8.30E-04</td>
			<td>7.48</td>
			<td>2.55</td>
			<td>1870</td>
			<td>2.83</td>
			<td>6。5</td>
		</tr>
<tr>
<td>D</td>
			<td>TRILOBE</td>
			<td>2.89E-03</td>
			<td>2.28</td>
			<td>2.28</td>
			<td>970</td>
			<td>0.76</td>
			<td>69。3</td>
		</tr>
<tr>
<td>电子邮件</td>
			<td>缸</td>
			<td>1.55E-03</td>
			<td>3.54</td>
			<td>2.55</td>
			<td>那</td>
			<td>1.37</td>
			<td>39。7</td>
		</tr>
</tbody></table>表 1:在大块粉碎研究中使用的催化剂及其性能.表1显示了催化剂的性质和衍生应力特性, 允许计算在压缩过程中, 在大块粉碎强度测量中的纵横比的降低。从 Beeckman et 201718中改编
<img alt="Figure 1" class="xfigimg" src="/files/ftp_upload/57163/57163fig1.jpg"> 图 1: 三点弯曲的催化剂挤出的外力 F.催化剂的示意图表示法和在两个支撑点中间应用的力的位置, 用于测定破裂的模量。弯曲的量是高度夸张的。根据弹性理论, 轴向应力在挤出的顶部是压缩的, 轴向应力在挤出的底部是拉伸的。因此, 有一个轴与零应力, 这被称为质心。当底部的拉应力达到材料的抗拉强度或破裂的模量时, 挤出断裂在极端纤维位于底部和传播非常快速完成挤出失败。从 Beeckman et . 2016 16改编而成。<a href="/files/ftp_upload/57163/57163fig1large.jpg" target="_blank">请单击此处查看此图的较大版本.</a>
<img alt="Figure 2" class="xfigimg" src="/files/ftp_upload/57163/57163fig2.jpg"> 图 2: 挤出物对空聚碳酸酯表面的影响。高速摄影显示一个序列的两个催化剂挤出 impingements 对聚碳酸酯表面。镜头是0.1 毫秒, 除了对方。从 Beeckman et . 2016 16改编而成。<a href="/files/ftp_upload/57163/57163fig2large.jpg" target="_blank">请单击此处查看此图的较大版本.</a>
<img alt="Figure 3" class="xfigimg" src="/files/ftp_upload/57163/57163fig3.jpg"> 图 3: 纵横比作为放置高度的函数和影响的数量.纵横比作为一个函数的下降高度或严重性和数量的影响。对于高降高度, 渐近长宽比变化仅小, 因为挤出物到达他们的终端速度。从 Beeckman et . 2016 15改编而成。<a href="/files/ftp_upload/57163/57163fig3large.jpg" target="_blank">请单击此处查看此图的较大版本.</a>
<img alt="Figure 4" class="xfigimg" src="/files/ftp_upload/57163/57163fig4.jpg"> 图 4: 在具有较大初始长宽比的催化剂 A 1 滴后长宽比.在下拉前有大纵横比的一滴挤出物后的纵横比。对于这样长的挤出物, 第二个渐近线变得明显地是可见的, 即使在存在大量的实验错误由于使用的挤出物的有限的数量。从 Beeckman et . 2016 15改编而成。<a href="/files/ftp_upload/57163/57163fig4large.jpg" target="_blank">请单击此处查看此图的较大版本.</a>
<img alt="Figure 5" class="xfigimg" src="/files/ftp_upload/57163/57163fig5.jpg"> 图 5: 催化剂长宽比与负载应力 A.将长宽比作为应用载荷应力在大体积粉碎强度测量中的作用根据方法 ASTM D7084-04。当压力增加时, 长宽比保持恒定直到临界压力达到随后催化剂断裂到更小和更小的价值。每一个数据点是一个单独的测量与新鲜的催化剂从一开始。改编自 Beeckman et 201718<a href="/files/ftp_upload/57163/57163fig5large.jpg" target="_blank">请单击此处查看此图的较大版本.</a>

Watch this Scientific Journal Video about Predicting Catalyst Extrudate Breakage Based on the Modulus of Rupture at JoVE.com

Predicting Catalyst Extrudate Breakage Based on the Modulus of Rupture

在这里, 我们提出了一个协议, 以测量一个挤压催化剂的断裂模数和断裂的催化剂挤出物的碰撞表面或压缩在固定床上。

基于断裂模量的催化剂挤出断裂预测

The mechanical strength of extruded catalysts and their natural or forced breakage by either collision against a surface or by a compressive load in a ...

predicting-catalyst-extrudate-breakage-based-on-the-modulus-of-rupture

Nanyang Technological University

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Education

JoVE Core

JoVE Journal

Mechanical Engineering

Engineering

Unit 1

Principal Stresses under a Given Loading

SCIENTISTS IN ACTION

8.2K 次观看.  ExxonMobil Research and Engineering Company. 在这里, 我们提出了一个协议, 以测量一个挤压催化剂的断裂模数和断裂的催化剂挤出物的碰撞表面或压缩在固定床上。

视频: Predicting Catalyst Extrudate Breakage Based on the Modulus of Rupture

Synthesis of Programmable Main-chain Liquid-crystalline Elastomers Using a Two-stage Thiol-acrylate Reaction

This study presents a novel two-stage thiol-acrylate Michael addition-photopolymerization (TAMAP) reaction to prepare main-chain liquid-crystalline elastomers (LCEs) with facile control over network structure and programming of an aligned monodomain. Tailored LCE networks were synthesized using routine mixing of commercially available starting materials and pouring monomer solutions into molds to cure. An initial polydomain LCE network is formed via a self-limiting thiol-acrylate Michael-addition reaction. Strain-to-failure and glass transition behavior were investigated as a function of crosslinking monomer, pentaerythritol tetrakis(3-mercaptopropionate) (PETMP). An example non-stoichiometric system of 15 mol% PETMP thiol groups and an excess of 15 mol% acrylate groups was used to demonstrate the robust nature of the material. The LCE formed an aligned and transparent monodomain when stretched, with a maximum failure strain over 600%. Stretched LCE samples were able to demonstrate both stress-driven thermal actuation when held under a constant bias stress or the shape-memory effect when stretched and unloaded. A permanently programmed monodomain was achieved via a second-stage photopolymerization reaction of the excess acrylate groups when the sample was in the stretched state. LCE samples were photo-cured and programmed at 100%, 200%, 300%, and 400% strain, with all samples demonstrating over 90% shape fixity when unloaded. The magnitude of total stress-free actuation increased from 35% to 115% with increased programming strain. Overall, the two-stage TAMAP methodology is presented as a powerful tool to prepare main-chain LCE systems and explore structure-property-performance relationships in these fascinating stimuli-sensitive materials.

A novel methodology is presented to synthesize and program main-chain liquid-crystalline elastomers using commercially available starting monomers. A wide range of thermomechanical properties was tailored by adjusting the amount of crosslinker, while the actuation performance was dependent on the amount of applied strain during programming.

的可编程主链液晶性弹性体用双级硫醇丙烯酸酯反应合成

This study presents a novel two-stage thiol-acrylate Michael addition-photopolymerization (TAMAP) reaction to prepare main-chain liquid-crystalline ...

科研

化学

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

Challenges in Rheological Characterization of Highly Concentrated Suspensions &#8212; A Case Study for Screen-printing Silver Pastes

A comprehensive rheological characterization of highly concentrated suspensions or pastes is mandatory for a targeted product development meeting the manifold requirements during processing and application of such complex fluids. In this investigation, measuring protocols for a conclusive assessment of different process relevant rheological parameters have been evaluated. This includes the determination of yield stress, viscosity, wall slip velocity, structural recovery after large deformation and elongation at break as well as tensile force during filament stretching.
The importance of concomitant video recordings during parallel-plate rotational rheometry for a significant determination of rheological quantities is demonstrated. The deformation profile and flow field at the sample edge can be determined using appropriate markers. Thus, measurement parameter settings and plate roughness values can be identified for which yield stress and viscosity measurements are possible. Slip velocity can be measured directly and measuring conditions at which plug flow, shear banding or sample spillover occur can be identified clearly. 
Video recordings further confirm that the change in shear moduli observed during three stage oscillatory shear tests with small deformation amplitude in stage I and III but large oscillation amplitude in stage II can be directly attributed to structural break down and recovery. For the pastes investigated here, the degree of irreversible, shear-induced structural change increases with increasing deformation amplitude in stage II until a saturation is reached at deformations corresponding to the crossover of G' and G'', but the irreversible damage is independent of the duration of large amplitude shear. 
A capillary breakup elongational rheometer and a tensile tester have been used to characterize deformation and breakup behavior of highly filled pastes in uniaxial elongation. Significant differences were observed in all experiments described above for two commercial screen-printing silver pastes used for front side metallization of Si-solar cells.

A protocol for a robust and application relevant rheological characterization of highly concentrated suspensions is presented. Silver pastes used for screen-printing application in solar cell production are employed as model systems.

挑战流变特性高度集中悬架 - 为例进行丝网印刷银浆

A comprehensive rheological characterization of highly concentrated suspensions or pastes is mandatory for a targeted product development meeting the ...

工程学

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

Traditionally, soft body armor has been made from poly(p-phenylene terephthalamide) (PPTA) and ultra-high molecular weight polyethylene. However, to diversify the fiber choices in the United States body armor market, copolymer fibers based on the combination of 5-amino-2-(p-aminophenyl) benzimidazole (PBIA) and the more conventional PPTA were introduced. Little is known regarding the long-term stability of these fibers, but as condensation polymers, they are expected to have potential sensitivity to moisture and humidity. Therefore, characterizing the strength of the materials and understanding their vulnerability to environmental conditions is important for evaluating their use lifetime in safety applications. Ballistic resistance and other critical structural properties of these fibers are predicated on their strength. To accurately determine the strength of the individual fibers, it is necessary to disentangle them from the yarn without introducing any damage. Three aramid-based copolymer fibers were selected for the study. The fibers were washed with acetone followed by methanol to remove an organic coating that held the individual fibers in each yarn bundle together. This coating makes it difficult to separate single fibers from the yarn bundle for mechanical testing without damaging the fibers and affecting their strength. After washing, fourier transform infrared (FTIR) spectroscopy was performed on both washed and unwashed samples and the results were compared. This experiment has shown that there are no significant variations in the spectra of poly(p-phenylene-benzimidazole-terephthalamide-co-p-phenylene terephthalamide) (PBIA-co-PPTA1) and PBIA-co-PPTA3 after washing, and only a small variation in intensity for PBIA. This indicates that the acetone and methanol rinses are not adversely affecting the fibers and causing chemical degradation. Additionally, single fiber tensile testing was performed on the washed fibers to characterize their initial tensile strength and strain to failure, and compare those to other reported values. Iterative procedural development was necessary to find a successful method for performing tensile testing on these fibers.

The primary goal of the study is to develop a protocol to prepare consistent specimens for accurate mechanical testing of high strength copolymer aramid fibers, by removing a coating and disentangling the individual fiber strands without introducing significant chemical or physical degradation.

解析高强共聚物芳纶纤维使其力学性能的测定

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

Determination of the Mechanical Properties of Flexible Connectors for Use in Insulated Concrete Wall Panels

This document contains recommendations for performing a non-standard, double-shear test suitable for both continuous and discrete insulated concrete sandwich wall panels (ICSWPs). Such a standardized test does not exist, but several iterations of this and similar tests have been performed in the literature to varying degrees of success. Further, the tests in the literature are rarely-if ever-described in detail or discussed at length with respect to the testing, data analysis, or safety procedures. A test specimen configuration is recommended herein, and variations are discussed. Important mechanical properties are identified from the load versus displacement data, and their extraction is detailed. The use of test data for design, such as for determining the stiffness of the connectors, is briefly demonstrated to show how ICSWP deflection and cracking behavior may be calculated. The strength behavior of panels may be determined using the full load versus displacement curve or only the maximum connector strength. Shortcomings and unknowns are acknowledged, and significant future work is delineated.

We propose a testing protocol that can be combined with widely available analytical methods to assess the mechanical properties of shear connectors for use in the design of insulated concrete wall panels to predict full-scale insulated panel behavior.

用于隔热混凝土墙板的柔性连接器的机械性能测定

This document contains recommendations for performing a non-standard, double-shear test suitable for both continuous and discrete insulated concrete ...

Mechanoluminescent Visualization of Crack Propagation for Joint Evaluation

In this study, methods for the mechanoluminescent (ML) visualization of crack propagation and mechanical behavior to evaluate adhesive joints are demonstrated and explained. The first step involved sample preparation; an air spray was used to apply ML paint to the surface of the adhesive joint specimens. The performance of the ML sensor was described to examine the measurement conditions. The results of ML sensing during a double cantilever beam (DCB) test and a lap-shear (LS) test are demonstrated as these are the most frequently and widely used methods for evaluating adhesives. Originally, it was difficult to directly quantify the crack tip and strain/stress distribution and concentration because the crack tip was too small, and the effects of the strain could not be observed. The mechanoluminescence, crack propagation, and mechanical behavior during mechanical testing can be visualized via the ML pattern during the adhesive evaluation. This allows for the recognition of the precise position of the crack tips and other mechanical behaviors related to structural failure.

In this study, a protocol is presented that describes the use of mechanoluminescent (ML) visualization for monitoring crack propagation and mechanical behavior during adhesive joint evaluation testing.

裂纹扩展的机械发光可视化用于联合评估

In this study, methods for the mechanoluminescent (ML) visualization of crack propagation and mechanical behavior to evaluate adhesive joints are ...

Performing Microscope-Mounted Y-Shaped Cutting Tests

Y-shaped cutting has recently been shown to be a promising method by which to understand the threshold length scale and failure energy of a material, as well as its failure response in the presence of excess deformation energy. The experimental apparatus used in these studies was vertically oriented and required cumbersome steps to adjust the angle between the Y-shaped legs. The vertical orientation prohibits visualization in standard optical microscopes. This protocol presents a Y-shaped cutting apparatus that mounts horizontally over an existing inverted microscope stage, can be adjusted in three dimensions (X-Y-Z) to fall within the objective&#39;s field of view, and allows easy modification of the angle between the legs. The latter two features are new for this experimental technique. The presented apparatus measures the cutting force within 1 mN accuracy. When testing polydimethylsiloxane (PDMS), the reference material for this technique, a cutting energy of 132.96 J/m2 was measured (32&#176; leg angle, 75 g preload) and found to fall within the error of previous measurements taken with a vertical setup (132.9 J/m2 &#177; 3.4 J/m2). The approach applies to soft synthetic materials, tissues, or bio-membranes and may provide new insights into their behavior during failure. The list of parts, CAD files, and detailed instructions in this work provide a roadmap for the easy implementation of this powerful technique.

Y-shaped cutting measures fracture-relevant length scales and energies in soft materials. Previous apparatuses were designed for benchtop measurements. This protocol describes the fabrication and use of an apparatus that orients the setup horizontally and provides the fine positioning capabilities necessary for in situ viewing, plus failure quantification, via an optical microscope.

执行显微镜安装的Y形切割测试

Y-shaped cutting has recently been shown to be a promising method by which to understand the threshold length scale and failure energy of a material, as ...

High Throughput Traction Force Microscopy Using PDMS Reveals Dose-Dependent Effects of Transforming Growth Factor-&#946; on the Epithelial-to-Mesenchymal Transition

Cellular contractility is essential in diverse aspects of biology, driving processes that range from motility and division, to tissue contraction and mechanical stability, and represents a core element of multi-cellular animal life. In adherent cells, acto-myosin contraction is seen in traction forces that cells exert on their substrate. Dysregulation of cellular contractility appears in a myriad of pathologies, making contractility a promising target in diverse diagnostic approaches using biophysics as a metric. Moreover, novel therapeutic strategies can be based on correcting the apparent malfunction of cell contractility. These applications,&#160;however, require direct quantification of these forces.
We have developed silicone elastomer-based traction force microscopy (TFM) in a parallelized multi-well format. Our use of a silicone rubber, specifically polydimethylsiloxane (PDMS), rather than the commonly employed hydrogel polyacrylamide (PAA) enables us to make robust and inert substrates with indefinite shelf-lives requiring no specialized storage conditions. Unlike pillar-PDMS based approaches that have a modulus in the GPa range, the PDMS used here is very compliant, ranging from approximately 0.4 kPa to 100 kPa. We create a high-throughput platform for TFM by partitioning these large monolithic substrates spatially into biochemically independent wells, creating a multi-well platform for traction force screening that is compatible with existing multi-well systems.
In this manuscript, we use this multi-well traction force system to examine the Epithelial to Mesenchymal Transition (EMT); we induce EMT in NMuMG cells by exposing them to TGF-&#946;, and to quantify the biophysical changes during EMT. We measure the contractility as a function of concentration and duration of TGF-&#946; exposure. Our findings here demonstrate the utility of parallelized TFM in the context of disease biophysics.

We present a high throughput traction force assay fabricated with silicone rubber (PDMS). This novel assay is suitable for studying physical changes in cell contractility during various biological and biomedical processes and diseases. We demonstrate this method's utility by measuring a TGF-&#946; dependent increase in contractility during the epithelial-to-mesenchymal transition.

使用 PDMS 的高通量牵引力显微镜揭示了转化生长因子的剂量依赖效应 - 对中皮到中位过渡的影响

Cellular contractility is essential in diverse aspects of biology, driving processes that range from motility and division, to tissue contraction and ...

Fibroblast Derived Human Engineered Connective Tissue for Screening Applications

Fibroblasts are phenotypically highly dynamic cells, which quickly transdifferentiate into myofibroblasts in response to biochemical and biomechanical stimuli. The current understanding of fibrotic processes, including cardiac fibrosis, remains poor, which hampers the development of new anti-fibrotic therapies. Controllable and reliable human model systems are crucial for a better understanding of fibrosis pathology. This is a highly reproducible and scalable protocol to generate engineered connective tissues (ECT) in a 48-well casting plate to facilitate studies of fibroblasts and the pathophysiology of fibrotic tissue in a 3-dimensional (3D) environment. ECT are generated around the poles with tunable stiffness, allowing for studies under a defined biomechanical load. Under the defined loading conditions, phenotypic adaptations controlled by cell-matrix interactions can be studied. Parallel testing is feasible in the 48-well format with the opportunity for the time-course analysis of multiple parameters, such as tissue compaction and contraction against the load. From these parameters, biomechanical properties such as tissue stiffness and elasticity can be studied.

Presented here is a protocol to generate engineered connective tissues for a parallel culture of 48 tissues in a multi-well plate with double poles, suitable for mechanistic studies, disease modeling, and screening applications. The protocol is compatible with fibroblasts from different organs and species and is exemplified here with human primary cardiac fibroblasts.

成纤维细胞衍生的人类工程结缔组织用于筛查应用

Fibroblasts are phenotypically highly dynamic cells, which quickly transdifferentiate into myofibroblasts in response to biochemical and biomechanical ...

A Method to Study the Correlation Between Local Collagen Structure and Mechanical Properties of Atherosclerotic Plaque Fibrous Tissue

The rupture of atherosclerotic plaques in coronary and carotid arteries is the primary cause of fatal cardiovascular events. However, the rupture mechanics of the heterogeneous, highly collagenous plaque tissue, and how this is related to the tissue's fibrous structure, are not known yet. Existing pipelines to study plaque mechanics are limited to obtaining only gross mechanical characteristics of the plaque tissue, based on the assumption of structural homogeneity of the tissue. However, fibrous plaque tissue is structurally heterogeneous, arguably mainly due to local variation in the collagen fiber architecture.
The mechano-imaging pipeline described here has been developed to study the heterogeneous structural and mechanical plaque properties. In this pipeline, the tissue's local collagen architecture is characterized using multiphoton microscopy (MPM) with second-harmonic generation (SHG), and the tissue's failure behavior is characterized under uniaxial tensile testing conditions using digital image correlation (DIC) analysis. This experimental pipeline enables correlation of the local predominant angle and dispersion of collagen fiber orientation, the rupture behavior, and the strain fingerprints of the fibrous plaque tissue. The obtained knowledge is key to better understand, predict, and prevent atherosclerotic plaque rupture events.

We have developed a mechano-imaging pipeline to study the heterogeneous structural and mechanical atherosclerotic plaque properties. This pipeline enables correlation of the local predominant angle and dispersion of collagen fiber orientation, the rupture behavior, and the strain fingerprints of the fibrous plaque tissue.

基于断裂模量的催化剂挤出断裂预测

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