TA Instruments User Training

Transcription

1 TA Instruments User Training DSC 原 理 與 應 用 2012 年 9 月 7 日 國 立 台 灣 大 學 化 學 系 潘 貫 講 堂 (B 棟 積 學 館 2 樓 演 講 廳 ) 基 礎 應 用 許 炎 山 TA Instruments, Waters LLC 美 商 沃 特 斯 國 際 股 份 有 限 公 司 台 灣 分 公 司 TA Taipei office: 104 臺 北 市 長 安 東 路 1 段 23 號 4F 之 5 Tel: Fax: C/P: E/M : jhsu@tainstruments.com

2 DSC: Heat Flow Measurements Calorimeter Signals Time Temperature Heat Flow Signal Change Heat Flow, absolute Heat Flow, shift Exothermic Peak Endothermic Peak Isothermal Onset Properties Measured Specific Heat Glass Transition Crystallization or Cure Melting Oxidative Stability

3 DSC: Typical DSC Transitions Heat Flow exothermic Glass Transition Crystallization Melting Cross-Linking (Cure) Oxidation or Decomposition Temperature

4 Endothermic Heat Flow Heat Flow (W/g) Heat Flow Endothermic: heat flows into the sample as a result of either heat capacity (heating) or some endothermic process (glass transition, melting, evaporation, etc.) Exo Up Temperature ( 蚓 )

5 Exothermic Heat Flow 0.1 Heat Flow (W/g) 0.0 Heat Flow Exothermic: heat flows out of the sample as a result of either heat capacity (cooling) or some exothermic process (crystallization, cure, oxidation, etc.) -0.1 Exo Up Temperature ( 蚓 )

6 Heat Flow (cont.) Understanding DSC Signals (cont.) Where: dh dt = measured heat flow rate Cp = sample heat capacity = specific heat (J/g C) x mass (g) dt dt = measured heating rate f (T,t) = heat flow due to kinetic processes (evaporation, crystallization, etc.)

7 Understanding DSC Signals (cont.) Heat Flow Due to Heat Capacity Heat Capacity = Specific Heat (J/g C) x mass (g) For a given sample, the higher the heating rate, the higher the heat flow rate. Therefore, high heating rates increase sensitivity to detect weak transitions Heat Flow Rate = mwatt = mj/sec The heat flow rate becomes endothermic as heating of the sample begins (due to sample Cp at that temperature) and becomes more endothermic at higher temperature due to increasing sample Cp at higher temperature During cooling, the heat flow signal is exothermic

8 Understanding DSC Signals (cont.) Heat Flow Due to Heat Capacity (cont.) Absolute Heat Capacity or Specific Heat (J/g C) is important because: 1. It is required by engineers to develop systems that heat or cool materials 2. It is a measure of molecular mobility Vibration occurs below and above Tg Rotation polymer backbone and sidechains (in and above Tg) Translation polymer molecule (above Tg) Changes in heat capacity are important because they signal significant changes in the physical properties of a material

9 Heat Flow Due to Heat Capacity

10 Tg is a Step Change in Heat Capacity Heat Capacity (J/g/ C) Heat Capacity Heat Flow Temperature Below Tg - lower Cp - lower Volume - lower CTE - higher stiffness - higher viscosity - more brittle - lower enthalpy Glass Transition is Detectable by DSC Because of a Step-Change in Heat Capacity [ ] Heat Flow (mw) Exo Up Temperature ( C) -1.0 Universal V3.8A TA Instruments

11 Heat Flow Due to Kinetic Events

12 Applications Thermoplastics Thermosets Pharmaceuticals Heat Capacity Glass Transition Melting and Crystallization Additional Applications Examples

13 Thermoplastic Polymers Semi-Crystalline or Amorphous Crystalline Phase melting temperature Tm (endothermic peak) Amorphous Phase glass transition temperature (Tg) (causing ΔCp) Tg < Tm Crystallizable polymer can crystallize on cooling from the melt at Tc (Tg < Tc < Tm)

14 DSC of Thermoplastic Polymers Tg Melting Crystallization Oxidative Induction Time (OIT) General Recommendations 10-15mg in crimped pan 10 C/min

15 Thermoplastic: Heat/Cool/Heat Heat Flow (W/g) First Heat Cooling Second Heat [ ] Temperature ( C) Time (min) 0

16 Thermoplastic: Heat Flow vs. Temperature for H-C-H 1.5 Quenched PET 1.0 Cool 0.5 Heat Flow (W/g) 0.0 Second Heat First Heat Temperature ( C)

17 Calculation of % Crystallinity Sample must be pure material, not copolymer or filled Must know enthalpy of melting for 100% crystalline material (ΔH lit ) You can use a standard ΔH lit for relative crystallinity For standard samples: % crystallinity = 100* ΔH m / ΔH lit For samples with cold crystallization: % crystallinity = 100* (ΔH m - ΔH c )/ ΔH lit

18 PET Initial Crystallinity C 0.5 Heat Flow (W/g) C C(I) C C 53.39J/g Initial Crystallinity = C 74.71J/g C Temperature ( C)

19 Crystallinity by DSC Example: Crystallinity of Polyethylene obs ΔH f % Crystallinity = 100% ΔH Table: Heats of fusion of 100% crystalline polymers f Q: Where is my polymer in this table?

20 PET Initial Crystallinity Calculation C 0.5 Heat Flow (W/g) C C(I) C C 53.39J/g C 74.71J/g % crystallinity = 100* (ΔH m - ΔH c )/ ΔH lit -1.0 ( ) = 15% C Temperature ( C)

21 PET % Crystallinity 21J/g Initial Crystallinity or 15% Crystalline Does that sound right? The sample is quenched cooled PET We know that quenched cooled PET is 100% amorphous Why does DSC give us the wrong answer?

22 Change in Crystallinity While Heating 1.0 Quenched PET 9.56mg 10 C/min 蚓 蚓 71.96J/g Heat Flow (W/g) Integral (J/g) 蚓 蚓 J/g 蚓 蚓 Exo Up Temperature ( 蚓 ) Universal V4.0B TA Instruments

23 Crystallization Crystallization is a kinetic process which can be studied either while cooling or isothermally Differences in crystallization temperature or time (at a specific temperature) between samples can affect enduse properties as well as processing conditions Isothermal crystallization is the most sensitive way to identify differences in crystallization rates

24 Crystalline Structures Single Crystals Polymer Spherulites Sharmistha Datta & David J. W. Grant, Nature Reviews Drug Discovery 3, (January 2004)

25 Physical State Transitions Amorphous Polymer Crystalline Polymer Increasing Temperature Liquid Gum Rubber Liquid Flexible Thermoplastic T m T g T g Glass

26 Crystalline Structures Spherulite Morphology Folding and Re-entry (from Odian) Youyong Li and William A. Goddard III Macromolecules (22),

27 Effect of Cooling Rate on Crystallization

28 當 結 晶 速 率 太 快, 或 是 結 晶 熱 太 高 時 的 回 溫 現 象 Supercooling of Water C + Heat Flow (mw) C Temperature ( C)

29 Crystallization Crystallization is a two step process: Nucleation Growth The onset temperature is the nucleation (T n ) The peak maximum is the crystallization temperature (T c ) Crystallization is Temperature and Time dependence

30 Effect of Nucleating Agents crystallization POLYPROPYLENE WITHOUT NUCLEATING AGENTS POLYPROPYLENE WITH NUCLEATING AGENTS Heat Flow (W/g) Heat Flow (W/g) Exo Up melting Temperature ( 蚓 ) 0.0 Exo Up Temperature ( 蚓 )

31 What is Isothermal Hot Crystallization? A Time-To-Event Experiment Annealing Temperature Melt Temperature Isothermal Crystallization Temperature Time Zero Time

32 Isothermal Crystallization oc Polypropylene 4 Heat Flow (mw) oc oc oc oc oc oc Time (min)

33 降 溫 速 率 夠 快 嗎? Project RHC: Crystallization of LDPE

34 What is Isothermal Cold Crystallization? A Time-To-Event Experiment Annealing Temperature Melt Temperature Isothermal Crystallization Temperature Glass Transition Temperature Stand-by Temperature Time Zero Time

35 DSC Applications: Quench-Isothermal-Cold Crystallization Method Log: 1: Initial temperature: 高 於 Tm 2: Initial temperature: Tm 與 Tg 之 間 3: Mark end of cycle 1 4: Isothermal 恆 溫 結 晶 一 段 時 間 5: Mark end of cycle 2 6: Ramp 10.00C/min to 高 於 Tm 7: Mark end of cycle 3

36 DSC Applications: Quench-Isothermal-Cold Crystallization of PET Isothermal Ramp 10C/min

37 以 MDSC 決 定 樣 品 的 初 始 結 構 Modulated DSC Theory & Applications Advanced Tzero technology included in the Q2000, makes MDSC experiments both faster and the results more accurate. Heating rates equivalent to those commonly used in standard DSC (10 C / min) are now possible. Over 90% of the leading researchers performing MDSC, use systems from TA Instruments - a point to note when choosing a DSC system. * US Patent Nos. B1 5,224,775; 5,248,199; 5,335,993; 5,346,306; 5,439,291

38 DSC Heat Flow dh = dt DSC heat flow signal Cp = Sample Heat Capacity = Sample Specific Heat x Sample Weight dh dt = Cp + f (T, t) dt dt dt = dt Heating Rate f (T, t) = Heat flow that is function of time at an absolute temperature (kinetic)

39 Comparison of DSC and MDSC Signals dh dt = Cp dt dt + f (T, t) DSC Total Heat Flow MDSC Modulated Heat Flow Total Heat Flow Reversing Heat Flow Nonreversing Heat Flow Heat Capacity COMMENTS Signals contain all thermal events occurring in the sample Quantitatively the same in both techniques at the same average heating rate Heat capacity component of total heat flow Kinetic component of total heat flow All calculated heat flow signals are also available in heat capacity units

40 Average & Modulated Temperature: Heat-Iso Conditions Amplitude Average Temperature Modulated (Actual) Temperature Period

41 Average & Modulated Heating Rate: Heat-Iso Conditions Period Note that the rate never decreases below 0ºC/min

42 MDSC Heat-Cool Temperature Modulation Heating Rate goes below 0ºC/min

43 Calculation of MDSC Signals Total Heat Flow Equivalent to standard DSC at the same average heating rate Calculated from the average value of the Modulated Heat Flow The average and amplitude values of the Modulated Heat Flow are calculated continuously (every 0.1 seconds) using Fourier Transform analysis. This provides much better resolution than would be obtained from using the actual average and amplitude values that occur only twice over each modulation cycle.

44 MDSC Raw Signals Quenched PET Signals have an Average and an Amplitude

45 Calculation of MDSC Total Heat Flow Quenched PET

46 Calculation of MDSC Signals Reversing Heat Flow Calculated from Reversing Heat Capacity signal Rev Cp = Heat Flow Amp Heating Rate Amp x KCp Rev Rev Heat Flow = Rev Cp x Avg Heat Rate

47 Calculation of Reversing Heat Capacity Signal Rev Cp = Heat Flow Amp Heating Rate Amp x KCp Rev

48 MDSC Reversing Heat Capacity Signal

49 Reversing Heat Flow and Heat Capacity

50 Calculation of MDSC Signals Nonreversing Heat Flow Calculated by subtracting the Reversing Heat Flow signal from the Total Heat Flow signal Total = Reversing + Nonreversing Nonreversing = Total Reversing dh dt = Cp dt dt + f (T,t)

51 MDSC Heat Flow Signals dh dt Total Heat Flow All Transitions = Cp dt dt + Reversing Heat Flow Heat Capacity Glass Transition Most Melting f (T, t) Non-Reversing Heat Flow Enthalpy Recovery Evaporation Crystallization Thermoset Cure Denaturation Decomposition Some Melting

52 Calculated MDSC Heat Flow Signals Quenched PET

53 MDSC Applications: True Range of Melting Estimated Onset of Melting from Standard DSC

54 MDSC Applications: True Range of Melting Estimated Onset of Melting from Standard DSC Estimated Onset of Melting from MDSC The onset of melting is shown to be 65ºC lower than estimated from Standard DSC

55 Polymers; DSC of Complex Polymer Blend Where are the glass transitions in this engineering plastic?

56 Polymers; MDSC of Complex Polymer Blend

57 Polymers; DSC of PET/PC Mixture Sample: Quenched PET and PC Size: mg Method: Comment: PET13.60/PC 10.40/Al film 0.96mg DSC File: C:...\Len\Crystallinity\qPET-PCdsc Standard 10 C/min 57% PET; 43% PC J/g Heat Flow (mw) C C C 13.31J/g C 42.95J/g C C [ ] Heat Flow (mw) -18 Where is the glass transition of the DSC Heat Flow Analyzed Two Different Ways 100% amorphous polycarbonate? Exo Up Temperature ( C) Universal V3.8A TA Instruments

58 Polymers; MDSC of PET/PC Blend Sample: Quenched PET and PC Size: mg DSC Method: Comment: MDSC PET13.60/PC 10.40/Al film 0.96mg -2.0 File: C:\TA\Data\Len\Crystallinity\qPET-PC Cold Crystallization Peak Seen Only in Total Signal -2.2 Total Heat Flow Heat Flow (mw) Reversing Heat Flow Decrease in Heat Capacity Due to Cold Crystallization Glass Transition of Polycarbonate True Onset of Melting [ ] Rev Heat Flow (mw) Exo Up Temperature ( C) Universal V3.8A TA Instruments

59 Thermosetting Polymers A + B C Thermosetting polymers react (cross-link) irreversibly. A+B will give out heat (exothermic) when they crosslink (cure). After cooling and reheating C will have only a glass transition Tg. GLUE

60 EPOXY Resin Time-Temperature-Transformation (TTT) diagram Phase Transformations (Gel and Vitrification) EPOXY Resin Curing 的 過 程 Gel 凝 膠 化 / Vitrification 玻 璃 化

61 DSC of Thermosetting Polymers Tg Curing Residual Cure General Recommendations mg in crimped pan if solid; hermetic pan if liquid 10 C/min

62 如 何 表 徵 熱 固 性 樣 品 :DSC 動 態 升 溫 法 與 恆 溫 法 The degree of cure is defined as follows: α = ΔH ΔH t R

63 Thermoset: Comparison of 1st & 2nd Runs First 蚓 Heat Flow (W/g) Second Tg Tg 蚓 20.38J/g Residual Cure Temperature ( 蚓 )

64 Determination of % Cure DSC Conditions: Heating Rate = 10 蚓 /min. Temperature Range = -50 蚓 to 250 蚓 N2 Purge = 50mL/min J/g % cured Under-cured Sample Heat Flow (W/g) 蚓 (H) 蚓 (H) 79.33J/g % cured Optimally-cured Sample NOTE: Curves rescaled and shifted for readability Exo Up Temperature ( 蚓 ) Universal V2.4F TA

65 Effect of Aging/Storage below Tg 物 理 老 化 的 影 響 Physical property Specific Volume Modulus Coefficient of thermal expansion Specific Heat Enthalpy Entropy Enthalpic Relaxation Response on storage below Tg V, Decreases 1/E, Increases CTE Cp Decreases H S Decreases Decreases Decreases Increases Storage time Temperature

66 物 理 老 化 對 於 DSC 熱 流 在 Tg 範 圍 產 生 的 影 響 Determination of Tg/Cure Factor (Delta Tg) 發 生 錯 誤 的 判 斷 (Xiangxu Chen, Shanjun Li,1990)

67 剖 析 ΔTg 的 爭 議 革 新 DSC 實 驗 手 法 的 結 果

68 預 熱 法 可 以 釐 清 ΔTg 的 爭 議

69 MDSC Glass Transition of Epoxy Coating TOTAL REVERSING

70 MDSC Glass Transition of Solder Mask

71 MDSC Applications: Separating Overlapping Transitions in Epoxy Prepreg Enthalpy recovery peak due to physical aging Glass Transition of Epoxy

72 MDSC Applications: Separating Overlapping Transitions in Epoxy Prepreg Tg is over 3ºC higher in aged sample Aged Epoxy Cycled Epoxy (physical aging removed)

73 MDSC of Thermoset Cure While Heating Sample: Epoxy Size: 9.79 mg Method: MDSC at 0.5 C/min Decrease in Cp Due to Crosslinking (Vitrification) Reversing Heat Capacity 1.6 Heat Flow (mw) Increase in Cp Due to Linear Polymerization Total Heat Flow Increase in Cp Due to Devitrification [ ] Rev Cp (J/g/ C) C 319.8J/g Exo Up Temperature ( C) Universal V3.8A TA Instruments

74 Epoxy Cure with Isothermal MDSC min Cure 100 C Sample: Epoxy Size: mg Method: MDSC Iso at 100 C Heat Flow (mw) J/g 75.30min Decrease in Cp Due to Crosslinking (Kinetics become Diffusion Controlled) Residual Cure 3 C/min [ ] Temperature ( C) [ ] Rev Cp (J/g/ C) C for 160 min Temperature 31.06J/g Exo Up Time (min) Universal V3.8A TA Instruments

75 Polymers; Advantage of MDSC for Post Cure Analysis of Epoxy Resin 0.2 Heating Experiment at 3 C/min after 160min Isothermal 100 C Heating Experiment at 3 C/min After 160 min Isothermal Cure at 100 C Note Onset of Decomosition before Complete Cure 0.4 Heat Flow (mw) Sample: Epoxy Size: mg Total Reversing Nonreversing C C 31.08J/g Note inability to see Tg in Total (like DSC) signal Note Inability to Measure Tg [ ] Nonrev Heat Flow (mw) [ ] Rev Heat Flow (mw) C(H) J/g/ C All Signals at Same Sensitivity -1.4 Exo Up Temperature ( C) Universal V3.8A TA Instruments

76 Most Common Applications of MDSC; Amorphous Structure The size (J/g C) and temperature of the glass transition provide useful information about the amount and physical state of amorphous material in a sample. The glass transition temperature (Tg) is important because the sample undergoes a significant change in physical and reactive properties at this temperature Measurement of the glass transition is important to nearly all DSC users. Because of the significant change in properties at Tg, it is often difficult to measure Tg by standard DSC.

77 Polymers/Drugs; 5 C/min for Drug Delivery System Using Polymer Microspheres Where are the glass transitions of amorphous drug dispersed in amorphous polymer?

78 Polymers/Drugs; 2 C/min for Drug Microspheres Shows Polymer/Drug Miscibility Single Tg seen in Reversing signal indicates Drug is soluble in polymer

79 Drugs; Use of MDSC to Detect Tg in Drug Formulation

80 Drugs; MDSC of a Cold/Allergy Tablet Indicates Decomposition, Not Melting Lack of endothermic peak in the Reversing signal indicates the sample is decomposing and not melting

81 Drugs; TGA Analysis of Cold/Allergy Tablet Shows Decomposition Between 100 and 150ºC

82 Selecting MDSC Experimental Conditions (Pan Type) Pan Type Always do TGA experiment to determine volatile content and decomposition temperature Volatilization can hide other transitions Volatilization can affect sample properties or even structure Select pan type (crimped vs. hermetic) based on volatile content and desire to lose or retain volatiles In general, select thinnest, lightest pan possible for the sample/application Thin, light pans provide better heat transfer and will permit shorter modulation periods and faster average heating rates

83 TGA Data Shows 5% Weight Loss in Drug Monohydrate

84 It Does Matter What Pan you use Monohydrate Pharmaceutical sample

85 MDSC Shows Increase in Cp During Loss of Water Due to Dehydration of Crystalline Hydrate Non-Hermetic Pan

86 20.0 C 1.33J/(g C) Drugs; MDSC Provides Sensitive and Accurate Measurement of Cp for Casein Protein

87 Drugs; MDSC of Albumin Protein Shows Broad Glass Transition and an Endothermic Process at Tg on 1 st Heat

88 Drugs; MDSC of Albumin Protein Shows Shows Just a Broad Glass Transition on 2nd Heat

89 Drugs; MDSC Provides an Accurate Measurement of Tg for Freeze-Drying

90 Enthalpy Plots Are Integrals of Heat Capacity Plots Integrals of 100% Crystalline and 100% Amorphous Heat Capacity Curves Can Be Used to Create an Enthalpy Plot Figure 1 Drug 3.75mg MDSC.159/60/1

91 Figure 2 Effect of the Temperature-Dependence of the Heat of Fusion on Crystallization and Melting Peak Areas for a Drug

92 The Enthalpy Plot Can Be Used to Calculate % Crystallinity Illustrating the Temperature Dependence of the Heat of Fusion on the Monohydrate Form of the Drug Figure 3

93 Figure 4; % Crystallinity of C Use of ATHAS Databank to Calculate % Crystallinity on 12.64mg Sample of Quench Cooled PET after Cold Crystallization 20 C/min