玻璃化转变温度 (Tg) 是定义材料完整性、制造条件和操作指南的基本材料特性，适用于聚合物、电子产品和先进材料等应用领域。玻璃化转变可以通过三种热分析技术进行测量：DSC、TMA 和 DMA 各有其适用的材料和应用。这篇博客将解释这些技术如何测量Tg，以及何时应该选择哪种技术。

玻璃化转变是指非晶态材料在加热时从玻璃态转变为橡胶态，或在冷却时从橡胶态转变为非晶态的温度区域。玻璃化转变实际上发生在一定的温度范围内，但通常被报道为一个单一的温度，称为 Tg。

了解玻璃化转变温度有助于解答一些重要问题，例如：

• 印刷电路板（PCB）在什么温度下有分层风险？
• 注塑成型或聚合物共混而不发生降解的理想温度是多少？
• 材料在使用过程中会发生变形或开裂吗？

玻璃化转变可以通过DSC、TMA和DMA来测量。这些热学技术均基于玻璃化转变过程中不同材料特性的变化来检测 Tg。选择正确的方法对于获得可靠的数据和对材料进行定量比较至关重要。

差示扫描量热法（DSC）是测量玻璃化转变最常用的方法。DSC 测量样品相对于惰性参考物的热量流入和流出，揭示热容变化，用于定义玻璃化转变。这些热容变化产生了三个温度值：玻璃化转变的起始温度、转变的中点温度和转变的结束温度。

实验设计对DSC结果至关重要。更高的加热速率可以提供更高的灵敏度，但由于仪器效应、样品热导率和转变动力学，会使 Tg 发生偏移。尽管如此，现代 DSC 仪器仍具有优异的基准性能，并且当与高加热速率相结合时，可为非晶态、半结晶态和增塑材料以及热固性树脂提供可靠的 Tg 测量。DSC 可以同时测量熔融、结晶和固化反应，提供其他方法所缺乏的额外热数据。

调制差示扫描量热法 (MDSC) 通过施加振荡热流，提供有关可逆和非可逆转变的更多信息。虽然体积弛豫吸热峰可能会扭曲传统 DSC 的 Tg，但 MDSC 将体积弛豫吸热峰与 Tg 处的热容变化逆向变化分离，从而获得更可靠的测量结果。MDSC 还可以区分不可逆转变（如冷结晶和固化），并提供检测与加热速率相关的转变的灵敏度。MDSC 对半结晶聚合物、多层薄膜或部分固化的热固性材料尤其有价值。

热机械分析 (TMA)是根据样品受热时尺寸的变化来测量玻璃化转变的。Tg 可以通过热膨胀的变化来测量，也可以通过探针穿透深度的增加来测量，因为材料在玻璃化转变过程中会软化。膨胀模式适用于刚性热塑性塑料和具有明确膨胀过渡的材料，而渗透模式更适用于在 Tg 以上明显软化的材料，例如较软的聚合物、涂料、粘合剂和一些弹性体。

对于填充、高度结晶或交联的材料，TMA 比 DSC 更合适，因为在 Tg 处观察到的尺寸变化通常很显著。然而，TMA 测得的 Tg 曲线通常较宽，可能受到探针加载条件的影响，并且可能受到体积弛豫效应的影响。

动态力学分析 (DMA)通过施加振荡的机械应力或应变来测量机械刚度和能量吸收的变化。随着分子运动在玻璃化转变过程中增加，储能模量（E’）急剧下降，使得DMA成为测定Tg最灵敏的技术之一。这种灵敏度非常适合检测高填充、结晶或交联材料中非晶态含量极低的Tg。

可以使用三个 DMA 事件来定义玻璃化转变的范围。储能模量起始点 (E’) 标志着玻璃化转变的开始，损耗模量峰值 (E”) 是玻璃化转变的中点，损耗角正切峰值代表转变的上限。

DSC、TMA 和 DMA 在测定不同材料的 Tg 时各有其优势和劣势。下表总结了根据我们的研究，不同热分析技术在评估不同材料的玻璃化转变温度（Tg）方面的相对效用：

有关更多信息和分析，请阅读完整的应用说明《探索热分析技术对玻璃化转变的敏感性》 。我们的免费热分析选型指南中提供了更详细的分析，介绍了哪些热分析仪器适合特定的应用。

您上次在百吉饼上涂抹 奶油奶酪 时，是否注意到涂抹起来有多容易（或多困难）？您是否习惯摇晃沙拉酱以重新混合分离的油和醋？在这两种情况下，您餐点的货架稳定性、分配和质地都通过流变学的核心基础得到了保证。

这门科学学科融合了物理学和化学的原理，旨在研究材料在不同应力水平下变形和流动的方式。在食品生产中，潜在的流变行为对于保持质量、客户满意度和一致性至关重要。

流变学是研究材料流动和变形的学科，用于预测产品的行为并优化配方。对于食品和饮料，流变仪 可以测量和量化产品在被搅拌、挤压、涂抹或摇晃时的反应；它在加热或冷却时如何变化；甚至在食用时如何被感知。

流变学是确保新产品或重新配制产品质量的必备工具。食品配方的改变有多种原因，例如：应对特定成分的供应链问题、扩展以提供新口味、添加植物基或健康替代品，或者更换影响产品分配的环保包装。

无论您开发新产品或新配方的原因是什么，其流变学特性必须满足消费者的期望，才能在商业上取得成功。最终产品需要实现以下特性：

• 诱人的外观——不太稀，也不太结块
• 理想的质地和口感，不会太“稠”或太“稀”
• 顺畅的分配，易于倾倒、挤压或涂抹，且不会滴漏
• 在运输、商店货架和消费者厨房中的货架稳定性

在成功开发或重新配制产品后，食品制造商必须进行大规模生产。原材料或加工条件的变化可能导致批次产品无法满足消费者期望，甚至引发代价高昂的召回。将流变测量集成到生产现场的质量控制测试中，可以确保产品的一致性，并在产品出厂前就避免消费者不满。

对于食品生产设施的质量控制经理来说，流变学数据将有助于回答以下问题：

• 我们的产品在不同批次、不同时间以及不同地区之间是否保持一致？
• 随着新设备或新配料的加入，产品的一致性是否发生了变化？
• 在拒绝某一批次产品之前，我们应认为多大的粘度或屈服应力变化是可以接受的？

对于任何食品或饮料，您都需要四个关键测量指标来了解该产品在生产、运输或消费过程中的表现。

粘度这描述了材料对运动的阻力。粘度存在于从浓稠（蜂蜜）到稀薄（可乐）的连续谱上。然而，许多食品和饮料是非牛顿流体，这意味着它们的粘度会随剪切力而变化。在许多情况下，这种变化是刻意设计的（例如，市场转向使用挤压瓶包装奶油奶酪或蛋黄酱等调味品）。

• 剪切稀化有些食品在静止时保持粘稠，但在咀嚼、搅拌、摇晃或涂抹时会变得相当稀薄。例如，花生酱在容器中时质地浓稠，但搅拌后会变得更软、更易涂抹。

屈服应力：有些食品在达到最低应力水平时会改变粘度。例如，如果您将打开的番茄酱容器倒置，番茄酱可能会根据其原始稠度保持在原位。然而，如果您通过摇晃或挤压对容器施加压力，番茄酱的颗粒就会分解。这使得顾客可以更容易地将番茄酱涂抹在汉堡或薯条上。

• 触变性这描述了产品在受力时粘度可能会先降低，但在应力消除后又恢复其结构的过程。低触变性食品能迅速恢复其原始结构，而高触变性食品则恢复得较慢。产品恢复到原始状态的速度快慢，会对批次一致性和客户满意度产生巨大影响。像蛋黄酱这样零触变性的材料会立即恢复其结构，而像酸奶这样高触变性的食品在搅拌后可能需要几天时间才能恢复其粘度。

温度、压力、摇晃、搅拌以及其他因素都可能影响产品的质地、口感和性能。这些干扰可能会有意（或无意）地永久改变产品在其生命周期每个阶段的行为。在以下四个关键领域使用流变学对于确保从开发到商店货架再到餐桌的产品质量至关重要。

我们都知道食品感觉不对劲是什么样，但您该如何衡量它呢？流变学使食品质量控制经理能够量化和定义他们希望产品具备的特性。通过设定所需的粘度、剪切变稀行为、屈服应力和触变性，您可以确保您的产品每次都保持一致。

食品生产实验室和制造商无需仅仅依赖昂贵且耗时的消费者小组，而是可以利用流变学来验证批次一致性或衡量配方变化的影响。流变学数据甚至可以与消费者小组的数据相关联，从而无需离开实验室即可预测客户满意度。

供应链中断、新法规或口味和质地的微小改进可能会促使您在商业生产过程中调整配方。流变学测量将帮助您更好地了解增稠剂、稳定剂和其他成分的变化如何影响产品的整体质地。这些测量结果将帮助您确定改进后的配方是否仍处于可测量参数的可接受且可预测范围内。

同样的测量结果也可能要求您更改生产过程中使用的工艺和设备。例如，如果您引入一种新的低脂奶油奶酪，其成分具有不同的屈服应力，您可能需要能够施加不同力的混合和灌装设备。

通过进行快速的批次间质量控制检查，流变学测量有助于您确信每天生产线上下线的最后一件产品将与第一件产品具有相同的质量。制造过程中微小且通常不可见的差异可能会对不同批次产生巨大的影响。例如，如果材料在加工过程中混合不足，它可能无法达到最终产品质地所需的正确特性。

最后，您需要确保在实验室中辛苦研发出的产品特性，与消费者在餐桌上体验到的特性保持一致。即使产品口感美味且食用安全，其从容器到餐桌的表现也会影响整体的享用体验。例如，罐装肉汁需要保持足够的粘度，即使在加热时也能“附着”在肉上。

流变学的灵敏测量有助于您在问题演变成代价高昂的召回或消费者放弃您的产品等更严重的问题之前，识别出潜在问题。在产品离开工厂前实施流变学质量控制检查，可为您提供在问题发生前采取主动纠正措施的信息。

为了获得这些重要知识，质量控制经理会使用现场流变仪，例如 Discovery Core Rheometer。

该仪器可帮助您了解悬浮液、凝胶、乳液、糊状物和其他非牛顿食品在不同条件下的变化。Discovery Core Rheometer 的主要功能包括：

1. 能够在各种实际存储和使用条件下获取产品完整粘度曲线的能力。
2. 易于使用的触摸屏，配有说明和插图，让您无需电脑或高级培训即可执行常规测量。
3. 紧凑的设计，比其他型号节省 75% 的台面空间。
4. 可自定义方法，以纳入您程序的每个步骤，并可根据您的规格即时显示“合格或不合格”读数。

如需了解流变仪工作原理的更多信息，请观看此 产品演示。

这是无法避免的。产品离开工厂后，将面临一系列压力因素。它可能会被加热或冷却、轻轻折叠或制成泥、用勺舀或涂抹、或被吸食或咀嚼。为确保您的食品在这些多变的环境中提供一致的效果，了解变形和流动至关重要。

只有流变学原理——以及测量它的仪器——才能定量地保证您始终如一地提供客户所期望的高质量产品。

如今的电池创新正不断突破极限，实现更高的能量密度、更高的功率以及更长的续航时间。然而，这些进步可能会带来严重的安全风险。在开放周期的早期阶段测量电池的安全性和稳定性，对于确保新设计在推进完整电池规模化量产前取得成功至关重要。

热稳定性是指材料在受热时抵抗降解的能力。对电池研发人员来说，幸运的是，材料科学领域已有一项成熟的技术可用于测量热流：差示扫描量热法 (DSC)。自 20 世纪 70 年代以来，Waters 材料科学事业部生产的 DSC 就广泛应用于聚合物、制药及其他材料科学研究领域。

电池研究人员和开发人员使用 DSC 来研究电池材料的热稳定性和分解行为，但传统的 DSC 并非专为电池测试而设计。当前的工作流程包括拆解电池单体，然后在 DSC 上对单个材料进行测试，但单独测试材料可能无法全面反映其热稳定性或交叉反应的情况。完整电池的安全测试往往被推迟到开发后期进行，这通常会导致高昂且耗时的整改成本。

Waters TA Instruments 纽扣电池差示扫描量热仪使电池研究人员和开发人员能够直接评估纽扣电池的安全性和性能，而无需拆解。如今，在开发的早期阶段便能实现完整电池的测试。这些测试可以通过识别可能引发自热或热失控的反应，为电池研发提供指导。然后，开发人员可以将这些数据与后期安全测试结果相结合，从而全面了解电池的稳定性。

点胶与流动特性对于多种电子制造工艺及材料至关重要。从焊膏与粘合剂的精确涂敷，到柔性电子和增材制造领域的新进展，流变学在提升加工性能、产品质量及制造一致性方面发挥着关键作用。

流变学研究的是受力时的变形与流动，这对于优化电子制造至关重要。流变学解答了各类电子应用中的关键问题，例如：

• 焊膏在储存过程中会发生什么变化？我该如何预测其保质期？
• 用于喷墨打印电子电路的理想粘度是多少？
• 我的薄膜或环氧树脂在干燥/固化前能否保持形状，还是会发生塌陷？
• 我的材料在注射器中是能顺畅流动，还是会发生堵塞？

这些特性具有剪切依赖性，这意味着材料的粘度（即流动阻力）会随着其在混合、点胶、储存或固化过程中所受作用力的变化而改变。因此，必须在宽广的剪切速率范围内对这些材料进行评估——这一点利用流变仪可以实现，而粘度计则无法做到。流变仪还能够测量随时间变化的材料的屈服应力，以预测其长期行为。

全球各地的研究人员和制造商利用Waters 流变仪来研究电子材料的点胶与流动特性。请阅读以下四个已发表的文章，了解流变学如何改善了其中的材料与工艺。

焊膏简化了电子产品的批量生产，但它属于一种化学活性混合物，需要谨慎处理与储存。焊膏中的粉末与助焊剂组分“在混合后即刻发生化学反应”，这意味着焊膏在制造、运输、储存及使用^全过程中都会发生持续变化，且均受温度与湿度的影响。流变仪能够控制剪切速率与形变，并具备高扭矩灵敏度，这使其成为“量化焊膏变化的最佳方法之一”。

焊膏制造商 Kester 公司的研究人员利用Discovery 混合流变仪（Discovery Hybrid Rheometer ）研究了焊膏的保质期及^各项性能。他们结合多种流变测试方法，开发出一种用于加速预测保质期的方法，研究结果表明，相比于储存时间，储存温度对焊膏最终使用时的粘度影响更大。

喷墨打印是实现包括柔性电子和可穿戴电子在内的印刷电子的关键技术。来自剑桥大学、江南大学和米兰理工大学的研究人员在纺织品上制备了喷墨打印的柔性且可水洗场效应晶体管（FET），从而实现了全喷墨打印电子电路。研究人员利用 Discovery 混合流变仪测量了^两种墨水配方的粘度随剪切速率的变化情况，并据此计算了最佳喷墨打印所需的各项可打印性指标，例如 Ohnesorge 数倒数（Z）的范围。

另一项研究利用非接触式微喷印技术制作了个性化的脑电图电子纹身。来自德克萨斯大学和加州大学洛杉矶分校的^研究人员开发出低粘度的生物相容性墨水，将其喷涂在头皮上后，墨水会“自干形成柔软、可拉伸且导电的薄膜”。利用 Discovery Hybrid Rheometer 30 测得的粘度数据，他们发现该墨水可调节的粘度特性及剪切变稀行为支持稳定的微射流打印。

增材制造是一项日益发展的技术，用于打印包括可穿戴设备、软体机器人和定制化储能装置在内的复杂电子结构。阿尔伯塔大学的研究人员开发了一种利用水性油墨通过直接墨水书写（一种增材制造形式）制备电容式压力传感器的新方法。他们利用ARES 流变仪证实，该油墨配方具有理想的剪切变稀特性：^即在流经狭窄的注射器时能够顺畅流动，而在被挤出并沉积到基底上后又能保持较高的粘度。该油墨的剪切变稀特性也意味着挤出所需的压力较低，从而“便于通过细小喷嘴顺畅挤出，形成连续图案”。

正如上述文章所示，流变学使得电子产品的制造与设计成为可能。从保质期到点胶和干燥，电子制造的每一个环节都受到流变特性的影响。量化这些特性是设计更高效工艺和创新产品的第一步。

如果您认为流变学过于复杂，或者与您的实验室无关，那么不妨重新考虑一下。领先的电子行业实验室已开始采用流变学技术，以便就材料配方、加工条件及保质期评估做出明智决策。请阅读我们的博客文章《揭开关于流变学的5大误区》 ，了解为何流变学与各水平的用户都息息相关且易于上手。

航空航天业正日益向轻量化方向发展，即在不牺牲机械强度、耐久性或性能的前提下，采用密度更低的材料。轻量化具有诸多优势，包括加快生产速度、提高能效以及改善可回收性。该方法的核心在于优化材料的强度重量比，使组件能够在保持或超越所需力学性能的同时，将总质量降至最低。

向轻量化方向的转变，与航空航天业向大规模、高产率生产转型的总体趋势相契合；这种转型要求能够更快速且具备可重复性地制造飞机、卫星及先进空中交通平台。在美国，NASA 致力于实现高效率制造，以提升美国的市场领导地位和成本效益^。1

轻量化得益于复合材料技术的进步，而复合材料现已成为航空航天领域的主导材料。预计未来六年，航空航天热塑性复合材料市场将以 16.8% 的复合年增长率增长，^这为能够满足该不断扩张市场独特需求的制造商提供了绝佳机遇。然而，生产用于航空航天领域的新一代轻质复合材料并非没有独特的挑战。本篇博文将探讨顶尖研究人员如何优化适用于航空航天领域的轻质高效复合材料，同时确保强度与性能不受影响。

夹层结构是一种多层高性能复合材料，由两层薄面板和一个轻质蜂窝状芯材组成。^这些材料具有高强度重量比和高刚度，使其成为航空航天应用的理想选择。有两种热分析技术适用于优化夹层结构，特别是在航空航天领域。热重分析（TGA）用于测定热稳定性和降解特性，帮助工程师选择在高温下不会丧失强度或发生失效的材料。差示扫描量热法（DSC）通过分析熔融、结晶和玻璃化转变行为，有助于确定理想的加工条件，并筛选出具有最佳相变特性的共混物。

研究人员利用 Waters TA Instruments 评估了不同的材料混合配方，开发出了新型 4D 打印生物基形状记忆夹层结构。^他们利用 Waters TGA 评估了新材料的热稳定性，证实了不同混合配方表现出几乎相同的热降解特性。他们利用符合 ASTM D3418 标准的 Waters DSC研究了熔融与结晶行为；结果显示，某些添加剂导致了玻璃化转变温度（Tg）的降低，且其中一种共混物表现出更显著的熔融吸热峰。这项分析对于确定不同混合物之间的差异以及选择最适合特定最终用途的混合物至关重要。

动态力学分析（DMA）为实现材料强度重量比的最大化提供了支持；该技术通过测量材料随时间、温度和频率变化的力学性能来进行分析。DMA（动态热机械分析）通过以下方式支持轻量化：量化储能模量以筛选高刚度、低质量的配方；表征阻尼特性（tan δ）以平衡结构刚度与振动耗散；以及监测热转变过程，确保材料在工作温度范围内保持足够的刚度。

高温推进系统依赖于BMI（双马来酰亚胺）等热固性材料，以利用其玻璃化转变温度（Tg）和热稳定性。NASA研究人员利用Waters DMA，在涵盖从低温到高温的典型火箭燃烧室工况下，对燃烧室用树脂进行了研究。测试结果证实，随着后固化温度的升高，玻璃化转变温度（Tg）^随之提高；但在低于Tg起始温度的所有温度范围内，模量均有轻微下降。

新型制造技术正在推动轻量化创新：感应焊接和超声波焊接能够高效实现大规模、高精度且品质一致的轻量化制造。DMA 通过评估储能模量和损耗模量随温度的变化情况，为焊接设计提供支持。研究人员利用^Waters DMA评估了预热对碳纤维/PEEK复合材料层合板超声波焊接的影响。数据表明，该材料的能量耗散能力随温度变化，这是焊接过程中生热的主要驱动因素。利用DMA（动态热机械分析），他们确定了损耗模量峰值——即材料将超声波振动转化为内部热能效率最高的点——并据此调整了预热工艺，以充分利用这一特性。

增材制造是另一种日益普及的轻量化材料生产方法，具有更高的自动化程度、复杂性、材料利用效率及设计灵活性。在近期的一项研究中，研究人员探讨了两种用于制造航空次承力结构碳纤维增强复合材料（ ^CFRP ）的增材制造方法。他们利用 Waters 动态热机械分析仪（DMA）研究了该材料的粘弹性行为与热转变特性，并使用热机械分析仪（TMA）测量了随时间、温度和力变化而产生的尺寸变化。他们发现，打印参数对尺寸稳定性有显著影响。

最后，热分析对于预测新型轻质材料的最终使用性能及安全性至关重要。例如，在开发用于飞机机身和机翼的复合材料T型接头时，研究人员利用DMA（动态热机械分析）、流变学和DSC（差示扫描量热法）研究了该接头在服役条件下的响应特性，以确保其在飞行过程中保持稳定。8^同样，Waters公司科学家发布的一份应用说明也展示了TGA（热重分析）在预测最终用途性能方面的重要性，因为它能够测定分解温度，并根据温度和时间估算聚合物的使用寿命^。9在这些研究中，热分析技术为那些专为严苛使用环境设计的新型轻质材料提供了最终用途性能预测支持，从而在降低风险的同时加速了创新进程。

上述研究表明，热力学分析对于验证轻质材料在严苛航空航天工况下的强度、使用寿命及稳定性至关重要。随着制造商不断追求更高的生产效率和更大幅度的减重，DSC、TGA、DMA 和流变学等技术提供了必要的数据，助力设计出不仅更轻，而且在整个使用寿命期间更安全、更可靠的材料。从优化加工条件到分析热降解，材料表征是实现轻量化安全与高效的基石。

1. Taminger, K. NASA 高速率航空结构技术计划；美国国家航空航天局，2020年。https://ntrs.nasa.gov/api/citations/20200004300/downloads/20200004300.pdf .
2. 拉贾特·佐佩。2032年航空航天热塑性复合材料市场规模与份额Persistence Market Research。https ://www.persistencemarketresearch.com/market-research/aerospace-thermoplastic-composites-market.asp （访问于 2026年5月18日）。
3. 嗯。Ilham Akbar; Bidayatul Armynah; Tahir, D. 夹层复合结构 (SCS)：以聚合物和金属为填料的木质电磁干扰（EMI）屏蔽材料研究综述Industrial Crops and Products 2024, 215, 118619–118619. https://doi.org/10.1016/j.indcrop.2024.118619 .
4. Ghalayaniesfahani, A.; Oostenbrink, B.; Kasteren, H. van; Gibson, I.; Mehrshad Mehrpouya.生物基形状记忆夹层结构的4D打印Polymer 2024, 307, 127252–127252. https://doi.org/10.1016/j.polymer.2024.127252 .
5. Stelter, C.; Park, C.; Chu, S.-H.; Hudson, T. 经历从低温到高温循环的复合材料缠绕燃烧室用后固化双马来酰亚胺树脂的动态力学分析。Nasa.gov. https://ntrs.nasa.gov/citations/20240012459 （访问于 2026-05-18）。
6. Takeda, S.; Kugi, D.; Hoshi, H.; Mohammad Fikry, MJ; Ogihara, S. 预热对CF/PEEK复合材料层合板超声波焊接的影响。Composite Structures 2025, 373, 119668. https://doi.org/10.1016/j.compstruct.2025.119668 .
7. Maier, R.; Istrate, AM; Despa, A.; Mandoc, AC; Bucaciuc, S.; Stoica, R. 增材制造技术制备的聚合物复合材料热力学响应研究。Materials 2022, 15 (14), 5069. https://doi.org/10.3390/ma15145069 .
8. 张涛, 罗震, 邓京, 裴雨, 程鑫. 基于预浸料-RTM共固化工艺的高弯曲性能复合材料螺栓连接T型接头制备新方法.Polymers 2024, 16 (9), 1259. https://doi.org/10.3390/polym16091259 .
9. Browne, J. 聚醚醚酮（PEEK）的热分析 – Waters TA Instruments。https ://www.tainstruments.com/applications-notes/thermal-analysis-of-polyether-ether-ketone-peek-ta496/ 。

As October ends and Diwali excitement fills the air, there’s a fun and colorful use of powders: the vibrant tradition of rangoli! This art form uses colorful powders to create intricate designs, symbolizing prosperity and welcoming the goddess of wealth and good luck. To achieve those beautiful, detailed designs, the powders need specific rheological properties—and that’s where powder rheology comes in.

Rangoli colors are as vibrant as Diwali itself, each adding joy to the festivities. Creating rangoli designs is a fun experience, especially with a variety of powders. When creating rangoli, you’ve probably noticed that sometimes, even when you get powders from the same factory, some colors flow smoothly while others can be a bit stubborn. This could be due to differences in additives and pigment properties. Differences in flow behavior due to things like additives and pigments are part of what powder rheology can help us understand.

As Diwali approached, we got our hands on five vibrant powders – red, blue, green, yellow, and white – all from the same factory. We thought, “Why not study their powder rheology and see how they behave?” Cool, right? So, we set up a little experiment in our backyard rheology lab using our powder rheology accessory.

When it comes to selecting materials for your next innovative product, the material specification sheet is likely the first place that you will turn. This document provides core properties measured by the manufacturer and serves as an essential tool for supplier verification and new product development. However, while these sheets are reliable and provide a standard method for comparison, they often fail to tell the whole story.

For successful material selection, product performance, failure prevention, it is important to go beyond the spec sheet and conduct in-house testing. This proactive approach will save you both time and money by facilitating informed material choices and enhancing product design.

A material specification sheet provides a snapshot of a material’s key properties as measured by the manufacturer. These properties are typically measured using standardized methods such as ASTM or ISO standards, offering some consistency and comparability across different materials. The spec sheet can be used for various purposes:

• Supplier Verification: Ensuring that the material provided by a supplier meets the necessary criteria for production.
• New Product Development: Aiding in the selection of new materials during the design phase of a product.

While spec sheets provide a foundational understanding, relying solely on them can be risky; they often provide incomplete information to know the material’s performance or predict lifetime of a product, especially in real-world application conditions.

Spec sheets are foundational for understanding general material properties, but they often lack detailed information about how a material will behave under specific conditions, such as the effects of different temperatures, prolonged stress or stress cycles, or exposure to harsh environments. Uncovering these blind spots is necessary for improving processing conditions, understanding material lifespan, and ultimately selecting the right material at the start of your development process.

To fully understand a material’s properties and ensure it meets your specific requirements, additional testing is required. Here are some critical aspects to consider:

Environmental Impacts

Materials can perform differently under various environmental conditions, such as UV exposure, or humidity. Due to the impracticality of inspecting materials in active use, such as polymer coatings on wires embedded in walls, a quick test lasting only a few minutes to hours is conducted to estimate the long-term stability of these materials over decades.¹

Differential scanning calorimetry (DSC) with oxidative induction time (OIT) analysis helps predict the aging and degradation of polymers, guiding material selection for longevity and reliability. For instance, polymers exposed to heat, oxygen, or light degrade faster, and OIT provides insights into their lifespan.

A variation of the OIT test, known as high-pressure OIT (HPOIT), is becoming increasingly popular. Proponents argue that oxidative data obtained under high pressure and temperature conditions align more closely with results from traditional, accelerated aging tests. The HPOIT test offers two primary advantages: high pressure raises the boiling points of additives, reducing their volatility, and it increases the concentration of the reacting oxidizing gas. This enables the use of lower test temperatures or significantly reduces test durations at comparable temperatures.²

Alternatively, high-pressure thermogravimetric analysis (HP-TGA) simulates extended exposure to harsh environments by using a combination of heat and elevated pressure. It is particularly useful for materials used in industrial applications, such as cabling for electrical or fiber optic systems. Safeguarding polymers against catastrophic degradation when exposed to direct sunlight or buried underground is crucial for these applications.³

Mechanical Behavior

Understanding the mechanical properties of materials beyond the scope of the datasheet is essential for nearly every application. For example, the following should be considered:

• Temperature Effects: Materials can exhibit drastically different properties at varying temperatures. Datasheets typically only list tensile properties at room temperature, but materials are frequently expected to perform under higher or lower temperatures.
• Long-Term Loading: What happens if a material is subjected to a load for weeks, months, or even years? Will it deform over time, i.e., creep? Will it crack under prolonged stress, i.e., creep rupture? For example, a clothing hanger may perform well under normal use, but storing a heavy coat over winter could cause the neck to elongate and eventually break. In this example, the clothing hanger began failing to perform its function (holding up clothes) due to creep and fell off the rod. Had it not fallen due to deformation, it would have eventually cracked due to creep rupture.

• Repeated Loading: In a process known as fatigue, repeated loading can cause accumulating damage, leading to fracture. It is important to know the stress levels and number of loading cycles a material can withstand before failure. Polymers exhibit fatigue in a very different way than metals and fatigue life estimates cannot be extrapolated from tensile strength as easily. Additionally, the usage temperature can have a significant impact on fatigue life at much lower temperatures than metals.

Mechanical test instruments evaluate durability and mechanical characteristics under various stresses (forces), frequencies, and environmental conditions. Specifically, Electroforce load frame instruments measure a sample’s response to force, whether it is a single push or pull (tensile test), repetitive load (fatigue), or creep/stress-relaxation test. Mechanical testing also accounts for environmental effects by testing in temperature-controlled air, gas, or fluid submersion.

Material testing is crucial in manufacturing and product development because it minimizes the risk of product failure, which can have costly and even dangerous consequences. Unexpected material behavior can lead to malfunctions, product recalls, and reputational damage.

For example, a woven fiberglass composite had a manufacturer’s recommended operating temperature up to 130°C. However, Dynamic Mechanical Analysis (DMA) testing revealed that the material’s storage modulus and loss modulus began to change around 100°C.⁴ Further fatigue testing data revealed that the material had a 90% reduction in its fatigue life at 100°C.⁵ Manufacturers could have mistakenly put this material into products used at high temperatures, such as baking, without realizing that it was highly likely to break.

Conducting thorough testing upfront provides higher confidence in material choices, ultimately saving time, money, and resources. Moreover, comprehensive material testing contributes to better long-term product reliability and performance. By thoroughly examining how a material responds to factors like fatigue, creep, and environmental degradation, manufacturers can design products that not only meet initial requirements but also maintain integrity throughout their life cycle. This proactive approach fosters innovation in product design, as engineers gain a deeper understanding of the material’s limits and capabilities, allowing for the creation of more efficient, safer, and longer-lasting products.

Going beyond the spec sheet is not just a recommendation; it is a necessity. By investing in additional testing, such as OIT using DSC and HP-TGA, you can uncover profound insights about material performance. By adding DMA and Electroforce fatigue testing to your testing suite, you can better predict material properties at various temperature conditions and repeat loading. These insights will ensure you make informed decisions that save time, money, and valuable resources by selecting the proper material for your application conditions. TA Instruments is here to support you with precision instruments and technical expertise, ensuring you have the tools needed to expertly evaluate materials and make the best decisions for your projects.

Biologic therapies derived from living organisms have revolutionized the treatment of complex diseases, yet their high development costs are often passed onto patients. Biosimilar drugs offer a promising solution to reduce costs while maintaining therapeutic efficacy. Unlike generic drugs, biosimilars cannot be exact replicas of their reference biologics due to their complex structures, necessitating rigorous testing and regulatory approval. Microcalorimetry, specifically Differential Scanning Calorimetry (DSC), plays a crucial role in this process by assessing the thermal stability of biosimilars to ensure they are structurally similar and perform equally to their reference drugs. In this blog, we examine why testing is crucial in the regulatory process and how instruments like the DSC are helping usher an influx of biosimilars to patients who need them.

Biologic treatments–those sourced from living things like proteins, stem cells, or genetic material–have saved and improved billions of lives. You, or someone you care about, has benefited from their unique ability to tackle some of our trickiest and deadliest diseases, be it insulin to control and treat diabetes, the mRNA vaccines that curbed and reversed the global COVID-19 pandemic, or immunotherapies helping to slow and reverse deadly cancers.

These pharmaceutical breakthroughs have, no doubt, made the world a healthier place, but not without requiring billions of investment dollars in research, development, and commercialization. That cost is ultimately passed on to insurance companies, healthcare providers, and patients themselves. Fortunately, there is a burgeoning solution to curb cost and increase access: Biosimilar drugs.

In this blog, we examine why biosimilars–despite offering comparable benefits to their “generic” small-molecule drug counterparts–undergo a more stringent regulatory process and how testing for thermal stability using Differential Scanning Calorimetry (DSC) is a critical step in ensuring these therapies function safely and effectively when they reach the patients who rely on them to stay alive.

Like generic drugs, biosimilars can be developed and prescribed once their breakthrough name-brand counterparts’ patent expires. Yet there’s one fundamental difference.

• Generic drugs have a small-molecule structure that is an exact copy of the original name-brand version. Think of Advil (the name-brand) and ibuprofen (the generic) or Lipitor and atorvastatin. The ability to reproduce a structurally perfect copy means a far more straightforward approval process. It also allows pharmacies to fill name-brand prescriptions with generic versions without additional testing or regulation.
• Biosimilars are precisely as the name suggests–similar versions to their name-brand biologic. Because they are sourced from living components, their structures are enormously complex. A perfect copy is impossible. That means, even if their treatment efficacy is the same, they require far more stringent testing and regulation before reaching the market. In particular, if the developer wants to create a therapy that will safely replace or interchange with the original treatment under the same prescription.

Both biosimilars and generics provide similar benefits to patients. More options mean easier access and lower cost. Yet a biosimilar’s journey from lab to patient is more complicated, which is why there are far fewer in the market.

Global regulatory agencies require a biosimilar to meet a specific set of criteria before entering the market. Despite not being molecularly identical to their name brand, a biosimilar must:

1. Use the same “mechanism of action:” The way in which the biosimilar interacts with, controls, or fights the illness must be identical to the original drug.
2. Use the same “route of administration:” If the original is administered through an injection, a patch, or a pill, the biosimilar needs to be delivered through identical means.
3. Be manufactured with a similar potency, purity, and dosage: The biologic’s efficacy can’t rely on more or less treatments or volume.
4. Undergo clinical trials to approve efficacy: However, this process is faster and less strenuous because the original biologic has already endured rigorous study. Which, of course, is why biosimilars are more affordable.

The goal, ultimately, is to ensure the biosimilar performs as well as its counterpart so that, even though it is slightly different at the micro level, it still provides the same effective treatment. But getting there doesn’t just require human trials; testing the formulation’s structure and stability in the lab is a critical early step.

In the past 15 years, countries worldwide have adopted similar regulatory processes to develop, test, and approve biosimilar drugs. Each includes an “Analytical Similarity Assessment“: a series of independent lab tests to prove that the structural properties of the biosimilar closely match the name brand.

‘Conformational Stability” is a fundamental component of the assessment. This tests how the drug’s structure changes through varying temperatures, time, or both. Researchers commonly use a specialized instrument called a Differential Scanning Calorimeter (DSC) to capture the necessary data for the assessment. The tool allows researchers to examine how multiple samples of a given compound transform or react to minute, precisely controlled temperature changes. To be considered a biosimilar, a new therapy must react to heat in the same way as the original biologic. Tools like the Nano DSC offer automated throughput and the highest level of measuring sensitivity to extract vital data during the regulatory process for low dose antibody drug products. Which means it is highly likely, and increasingly necessary, that the biosimilar drugs used in treatment today underwent some form of DSC testing.

The one disadvantage of traditional DSC instruments is that high concentration drug products require dilution to avoid damaging a fixed cell. The new TA Instruments RS-DSC solves this by using disposable micro fluidic chips, allowing for formulations with concentrations >20 mg/mL to be tested in their natural state, quickly and at scale. Ultimately, this provides the most accurate thermal stability data possible while mimicking real-world conditions.

Even if a biosimilar is approved, one additional regulatory hurdle must be surmounted for ubiquitous accessibility. In an ideal scenario, a biosimilar could be swapped for the original biologic at any time during the treatment (if, say, there is a shortage of the name-brand option or the cost becomes prohibitive).

When this option is available, the biosimilar has been approved for “interchangeability.” The drug has undergone human clinical trials and significant lab testing to ensure it behaves precisely the same way as its peer. This additional process differs from generic small-molecule drugs. Because they are functionally identical to their originals, this extra approval isn’t necessary.

But a biosimilar drug’s stability and efficacy can sometimes change, even when stored in the exact same conditions. Which is why testing, at the micro level, how and why the formulation changes compared to the name brand is critical. That can only be done prior to the human trial in a lab using a bevy of instruments, including DSC.

When more biosimilars reach commercialization, global healthcare becomes more accessible and equitable. It’s great news, then, that expiring patents and development innovations will ensure an influx of biosimilars in the near future. But the stringent, regulated process required before reaching patients is vital. Testing, whether done during human trials or earlier in the lab using DSCs along with other instrumentation, ensures that no matter where the treatment comes from, it’s as safe and effective as the blockbuster drug that inspired it.

The composites market is evolving fast. Global market projections indicate a 10.8 % growth by 2028, driven by the demand for composites across industries looking for materials with superior performance at reduced weight and cost.¹ This blog explores how advanced material analysis can enhance R&D and manufacturing processes in the composites market, ultimately leading to financial savings and increased efficiency.

While traditionally associated with the aerospace sector, composite materials have been adopted by several industries. Sectors actively utilizing composites include:

• Aerospace: Valued for their high strength-to-weight ratio, composites like carbon fiber reinforced polymer and aramid reinforced polymer enable the production of lighter, more fuel-efficient aircraft and satellites, contributing to reduced operational costs and increased payload capacities.²
• Automotive: A variety of automotive components, such as chassis and suspension systems, rely on composites for improved safety, fuel efficiency, and performance. Stringent emission regulations are driving this shift, including lightweighting automotive materials for enhanced fuel economy.³
• Renewable Energy: Composites are integral to the renewable energy sector, particularly in the construction of wind turbine blades and solar panel components. Companies are leveraging the dimensional stability, durability, and strength of these materials for operation under harsh environmental conditions, enhancing the longevity and efficiency of renewable energy systems.³
• Construction: Advanced composite materials, such as high-performance concrete mixes and fiber-reinforced polymers, can create structures more resistant to environmental degradation while offering excellent design flexibility. This improves construction longevity, reducing maintenance costs over time.⁴

While composites offer numerous advantages, manufacturers and material scientists face several challenges during their development and manufacturing including:

Designing and Selecting the Right Material

One of the main challenges in composites R&D is the selection of appropriate materials for specific applications. Researchers must consider criteria such as mechanical strength, thermal stability, and environmental resistance, which will entail the careful balancing of trade-offs between different performance characteristics.

Increased Complexity of Material Design

In achieving the desired balance of characteristics, scientists need to precisely control parameters such as filler orientation and distribution. Research has shown that the incorporation of nanofillers into a polymer matrix can bolster its mechanical properties and reduce water absorption in fiber-reinforced composites. As a result, strong interfacial adhesion is established between the matrix and nanofillers, allowing for efficient stress transfer during loading.

However, if not properly managed, the orientation and distribution of fillers within a composite can lead to variations in strength and other properties. The subsequent effect on the interfacial interactions can induce premature failure in the material.⁵

Sustainability

Reinforced polymer composites present several benefits, including the conservation of depleting resources such as metals and alloys. However, their disposal poses significant environmental challenges due to the non-biodegradable nature of petroleum-based polymers and synthetic fibers.

Consequently, research has increasingly focused on developing fully biodegradable and eco-friendly materials known as green composites. The use of green composites has significantly expanded across various engineering disciplines, yet the limited solubility of lignin-based materials for analytical purposes restricts the complete understanding and development of lignin-based green composites.⁶

New Manufacturing Techniques

Techniques like lightweighting and additive manufacturing deliver benefits but also introduce new challenges. Lightweighting replaces heavy materials with lighter-weight composites without compromising strength-to-weight ratios or structures’ fundamental design, while additive manufacturing increases throughput and design complexity. However, researchers must tackle the expensive nature of lightweighting processes, which can also risk impairing the ductility and formability of the materials, as well as concerns regarding the fabrication of composites with long fibers and complex cavities that surround additive manufacturing.^7,8

High Manufacturing Costs

Producing complex composite parts can require costly raw materials, specialized equipment, and skilled labor, leading to high costs. Effective quality control measures are essential to ensure that the final products meet the required standards without excessive waste or rework.⁹

To overcome these challenges, precise material analysis is essential. Key material properties to measure include:

• Glass Transition and Crystallinity: Differential Scanning Calorimetry (DSC) is a powerful technique for measuring the glass transition temperature and crystallinity of composites. These parameters are critical for understanding the thermal and mechanical properties of the material. For example, NASA uses a TA Instruments DSC to determine the quality of thermoplastic composite panels, which is vital for ensuring their performance in space applications.¹⁰ Further examples of real-world composites research using DSC can be found in our blog.
• Cure Kinetics, Cross-Linking, Gelation, and Cure Conversion: DSC paired with LED-PCA accessory can measure cure kinetics and the extent of cross-linking, gelation, and cure conversion in composite materials. These measurements help optimize processing conditions to achieve the desired mechanical properties and durability.^11,12
• Structural Relaxation, Time-Temperature Superposition, and Aging: Dynamic Mechanical Analysis (DMA) provides insights into the viscoelastic behavior of composites, including structural relaxation, time-temperature superposition, and aging effects. This information is key for predicting the long-term performance and stability of composite materials under various, sometime harsh, environmental conditions.¹³ Learn more about DMA testing of composites in this blog.
• Coefficient of Thermal Expansion: Thermomechanical Analysis (TMA) measures the coefficient of thermal expansion, which is important for understanding how composite materials will behave under thermal cycling. This is particularly relevant for applications where materials are exposed to varying temperatures, such as in aerospace and automotive industries.¹⁴

In response to the rising demand for materials that combine superior performance with low weight and cost, the composites market is rapidly expanding. This growth trajectory underscores the importance of addressing inherent challenges in the development and manufacturing of composites, such as selecting and designing appropriate materials, ensuring sustainability, implementing new manufacturing techniques, and managing high production costs.

Advanced material analysis techniques, including DSC, DMA, and TMA, are crucial in overcoming these challenges. These techniques provide critical insights into the thermal and mechanical properties of composites, enabling researchers and manufacturers to optimize processes and achieve the desired performance and durability.

TA Instruments supports composite R&D with cutting-edge material analysis instruments, helping you to overcome the complexities of composite design and manufacturing. By investing in advanced material analysis, companies can lower costs, increase efficiency, and stay competitive in the rapidly evolving composites market.

For more information on how TA Instruments can support the R&D of your composites, visit our composites page or contact us to speak with an expert.