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1、Training DMA,DMA Components,Q800 DMA 的内部结构图,测量的实验变量： 时间、频率、温度、应力、力、位移、应变 测量的材料性质： 模量、阻尼、蠕变、应力松弛、玻璃化转变、软化点,Dynamic Mechanical Analyzer (DMA),DMA 是热分析技术还是流变技术,定义 热分析 测量物质的物理性质与温度或时间的函数关系 流变学是研究就物质流动和形变的科学 DMA 是一类仪器的总称，它指的是先机械给予样品形变 尔后测量样品对于这种形变的响应. 形变可以通过正弦波的形式施加, 或通过恒定 (或步阶) 方式, 或以固定速率的方式施加. 可监控这种形变响
2、应与温度或时间的函数关系 。,固体的流变学?,流变学 研究物质流动与 形变 的科学.,研究固体聚合物流变学的重要性,高聚物的广泛使用 所需的力学性能 经济适用 对于聚合物的广泛应用, 聚合物的力学性能被认为是在聚合物的所有 物理和化学性能中最重要的性能 聚合物在应用过程中常须考虑的几个重要因素 需要力学行为的基础知识 需要了解力学行为是如何被变化的因素所改变的 流变学,典型无定形聚合物的粘弹性图谱,终端区域,橡胶平台区,转变区域,玻璃态,损耗模量 (E“ or G“),储存模量 (E or G),log E (G) and E“ (G“),很僵硬的固体,硬至软的橡胶,粘弹液体,Temperat
3、ure,固体的变形和模量,在施加的应力下，所有的材料会在形状或体积或二者兼而有之 发生变化 模量测量的是施加外力时，材料抵御形变的能力 模量 = 应力/应变 材料的三种模量 杨氏模量 (弹性模量) E 剪切模量 (刚性模量) G 体积模量 B,聚合物通常有较宽范围的力学强度,单个聚合物 能显示极端宽范围的力学强度变化 十分坚硬的固体 从硬至软的橡胶 粘弹液体 聚合物的力学强度 是以下因素的结果 聚合物的化学组成 表明力学性能在哪里会发生变化 聚合物的物理结构 力学性能会发生多大程度的变化,基本参数和单位,2,应力 = 力 /面积Pa, 或 dyn/cm s = 拉伸应力, t = 剪切应力 应
4、变 = 几何形状改变 无单位 e = 拉伸应变, g = 剪切应变 应变 或剪切速率 = 速度梯度 或d(strain)/dt 1/s e = 拉伸应变速率, g = 剪切应变速率 模量 = 应力 / 应变 Pa 或 dyn/cm E = 杨氏或 拉伸模量, G = 剪切模量 柔量 =应变 / 应力 1/Pa 或 cm /dyn Typically denoted by J 粘度 = 应力 /应变速率 Pa.s 或 Poise Denoted by h,2,.,.,2,动态力学或振荡测试,An oscillatory (sinusoidal) deformation (stress or st
5、rain) is applied to a sample. The material response (strain or stress) is measured. The phase angle , or phase shift, between the deformation and response is measured.,动态力学测试,Stress,Strain, = 0, = 90,理想弹性响应 (胡克固体),理想粘性响应 (牛顿流体),Stress,Strain,动态力学测试:经典极限响应,Phase angle 0 d 90,Strain,Stress,动态力学测试:粘弹性材
6、料响应,DMA 粘弹性参数:复合, 弹性, & 粘性应力,The stress in a dynamic experiment is referred to as the complex stress *,Phase angle d,Complex Stress, *,Strain, ,* = + i“,The complex stress can be separated into two components: 1) An elastic stress in phase with the strain. = *cos is the degree to which material beha
7、ves like an elastic solid. 2) A viscous stress in phase with the strain rate. “ = *sin “ is the degree to which material behaves like an ideal liquid.,DMA 粘弹性参数,弹性 (储存) 模量: Measure of elasticity of material. The ability of the material to store energy.弹性储存能指标,G = (stress/strain)cos,G“ = (stress/stra
8、in)sin,粘性 (损耗)模量: The ability of the material to dissipate energy. Energy lost as heat.变形消耗能量指标,模量: Measure of materials overall resistance to deformation.,G = Stress/Strain,Tan = G“/G,Tan Delta: Measure of material damping - such as vibration or sound damping.损耗因子,Storage and Loss of a Viscoelastic
9、 Material,SUPER BALL,TENNIS BALL,X,STORAGE,LOSS,DMA 粘弹性参数: 阻尼, tan ,Phase angle ,G*,G,G“,Dynamic measurement represented as a vector,The tangent of the phase angle is the ratio of the loss modulus to the storage modulus.,tan = G“/G,“TAN DELTA“ (tan ) is a measure of the damping ability of the materi
10、al.,动态应变扫描: 材料响应,Strain (amplitude),线性区域: 模量与应变 无关,E or G,非线性区域: 模量是应变的函数,Stress,gc = Critical Strain,Constant Slope,频率扫描: 材料响应,终端区域,橡胶平台区域,转变区域,类似于玻璃区,1,2,Storage Modulus (E or G),Loss Modulus (E“ or G“),log Frequency (rad/s or Hz),log E (G) and E“ (G“),动态升温 或步阶恒温扫描: 材料响应,Temperature,Terminal Regio
11、n,Rubbery Plateau Region,Transition Region,Glassy Region,log E (G) and E“ (G“),粘弹性图谱,log Frequency,Temperature,在各个粘弹区域的蠕变行为,Flow 190C,Plateau 150C,Glassy 70C,应力控制 DMA截面图,Motor Applies Force (Stress),Displacement Sensor - Measures Strain,Sample,Stress Controlled DMA (Rheometer) - Also referred to as
12、“single head“ or “open loop“ design.,内部结构截面图,独特专利-悬浮设计,模量计算,The instrument applies all calibrations and measures raw sample storage and loss stiffnesses (Ks). Modulus = Stiffness * Geometry Factor = Ks*GF,Dual Cantilever Single Cantilever 3-Point Bend,L = Sample Length I = Geometric Moment (distance
13、 between clamps) = for rectangular samples A = Cross Sectional Area n = Poissons Ratio F = Clamping Factor ( 0.9) S = Shearing Factor (1.5),DMA 夹具选择指导,DMA : 双悬臂夹具,Good general purpose mode (thermoplastics, elastomers) Highly damped materials can be measured Best mode for evaluating the cure of suppo
14、rted materials,Sample,Stationary Clamp,Movable clamp,双悬臂夹具适用模量范围,DMA : 单悬臂夹具模式,Best general purpose mode (thermoplastics) Same deformation mode as DMA 983 Preferred mode over dual cantilever for most neat thermoplastics (unreinforced) except elastomers Clamping torque is important,Sample,Stationary
15、Clamp,Movable clamp,单悬臂夹具适用模量范围,17.5 mm long 12.5 mm wide 3.2 mm thick,17.5 mm long 12.5 mm wide 1.75 mm thick,17.5 mm long 12.5 mm wide 0.5 mm thick,Geometry Factor (1/mm),Modulus (Pa),DMA : 三点弯曲夹具模式,Best mode for measuring medium to high modulus materials Conforms with ASTM standard test method fo
16、r bending Purest deformation mode since clamping effects are eliminated,Moveable Clamp,Force,Sample,Stationary Fulcrum,三点弯曲夹具适用模量测量范围,DMA : 拉伸夹具模式,Best mode for evaluation of thin films and fibers (bundle or single filaments) Small samples of high modulus materials can be measured TMA constant force
17、 & force ramp measurements (mini-tensile tester) Force Track & constant force control,活动夹具,样品 (film, fiber,or thin sheet),固定夹具,薄膜/纤维拉伸夹具适用模量范围,Geometry Factor (1/mm),Film,Fiber,DMA : 剪切夹具模式,Square sample configuration provides pure shear deformation Provides Shear Moduli: G*, G, G“ & G(t) Good for e
18、valuating highly damped soft solids such as gels and adhesives & elastomers Tg Can be used for high viscosity melts and resins,活动夹具,固定夹具,样品,剪切夹具适用模量范围,DMA : 压缩夹具模式,Good mode for low to medium modulus materials (gels,elastomers) Materials must provide restoring force (support necessary static load) O
19、ptions for expansion & penetration measurements,Stationary clamp,Sample,Movable Clamp,压缩夹具适用模量范围,DMA 校正,DMA 校正流程图,Clamp Position Instrument,Mass Zero Compliance,Electronics Force Dynamic,Balance Weight,典型的多重频率 DMA 扫描数据,乙烯基酯的主、次级转变测试,不同质量涂层的DMA扫描结果,DMA：增塑剂对乙烯基地板涂层的玻璃化转变的影响,DMA Film Clamp 1 Hz Scan 3C/min,Add 5%,Add 1%,Normal % Plasticizer,Less 1%,碳黑含量对橡胶弹性体力学性能的影响,DMA：包装薄膜的蠕变恢复实验,DMA：片状模塑料在剪切夹具中的固化研究,Frequency = 1Hz Amplitude = 20 microns,