Introduction of thermal analysis (DSC, TGA & DMA)

1. Introduction of thermal analysis (DSC, TGA & DMA)

2. Thermal Analysis • Differential Scanning Calorimetry (DSC) • Thermogravimetric Analysis (TGA) • Thermomechanical Analysis (TMA) • Dynamic Mechanical Analysis (DMA)

3. Thermal analysis

4. What is polymer or macromolecules ? Polymer = Poly + mer Macromolecules = Macro + molecule Synthetic polymer Natural (biopolymer) DNA RNA Protein Cotton PE DNA PP

5. Metallic elements Ceramic elements Polymeric elements Semiconductor elements

6. Main component of polymer Covalent bonding: different electronegativity. (electron are not even shared between them) Electrostatic forces between such dipoles can play an important role in determining polymer properties.

8. Defined by reaction to temperature A. Thermoplastics (Tp) ice and solder T Tp soft and could flow under stress T “ reversible ” B. Thermosets (Ts) egg and concrete T Ts soft and could flow under stress once T curing process + crosslinking “ not reversible ”

9. Polymers Thermoplastics Thermosets (No chemical change on heating) (Chemical change on heating) Uncured Cured Amorphous Crystalline Polystryene LOW/MEDIUM HIGH Epoxies Rubber Polycarbonate Nylon PPS Polyimides Silicones Polyurethanes PET PP Polyesters Neoprene Polysulfone LDPE HDPE Phenolics Epoxy Defined by reaction to temperature

10. Type Structure Example Poly(vinyl chloride), Polystyrene Polypropylene Poly(butyl methacrylate) Poly(imidazol pyrrolones) Linear Branched short chain Branched long chain Ladder Type of Polymer Chain Structure

11. Type Structure Example Type of Polymer Chain Structure (Continued) Phenol-formaldehyde resins Two crosslinked polymers not bonded to each other Crosslinked epoxy with vinyl polymer Star Network Interpenetrating network (IPN)

13. Types of bonds for polymers (1) Primary covalent (4) Ionic (2) Hydrogen bond (5) van der Waals (3) Dipole interaction ※(2) ~ (5) Secondary bonds

14. Secondary bonding Arises from interaction between dipoles • Fluctuating dipoles Adapted from Fig. 2.13, Callister 6e. • Permanent dipoles-molecule induced Adapted from Fig. 2.14, Callister 6e. -general case: Adapted from Fig. 2.14, Callister 6e. -ex: liquid HCl -ex: polymer

15. Bond distances and strengths rm：potential energy minima

16. Bonding and response to temperature In linear and branched polymers, only the secondary bonds hold the individual polymer chain together (neglecting temporary mechanical entanglements). ∴ As T↑, a point will be reached where the forces holding the chains together become insignificant, and the chains are then free to slide past one another flow under stress. ∴ Linear and branched polymers are TP. Crossing and network form the primary covalent bond as are the main chain. As T↑exceeds the dissociation energy of the primary covalent bonds, both main-chain and crosslink bonds fail randomly, and the polymer degrades. TS

17. Exception strong secondary interaction. ex polyacrylonitrile Polyacrylonitrile is capable of strong dipole interaction at the nitrile groups on every other carbon atom along the chains. Dissociation energy to “unzipped” the secondary bond is higher than those of C-C main chain’s degradation Polyacrylonitrile conatining not covalent bond Ts TP can be reused, but Ts can’t. Enviromental issue

18. Problem of using TS materials

21. 電子產品環境評估工具(EPEAT) 2006年7月，由美國環保署公佈的一項評量電子產品是否具有良好環境績效的工具 －『電子產品環境評估工具』(The Electronic Product Environmental Assessment Tool, EPEAT)，可幫助大型機構(包含政府機關與私人企業)在採買綠色電子產品時做為參考指標。採用自我宣告(self-declarations)的方式，線上註冊。EPEAT為產品設計提供清楚一致的標準，為製造商提供一安全銷售識別機會，並致力於降低產品對環境衝擊。目前EPEAT涵蓋的電子產品包含桌上型電腦(desktop computers)、筆記型電腦(notebooks)和電腦螢幕(computer monitors)，未來將會更進一步延伸擴展至所有電子產品。

22. 電子產品環境評估工具(EPEAT) （1）一套環境績效評估的標準 採用IEEE 1680對個人電腦產品的環境評估標準 － 美國國家標準(American National Standard)。此標準共51項，其中23項必要準則(required criteria)和28項選擇性準則(optional criteria)。 （2）一個識別和證明產品符合標準的系統 經評估並滿足特定標準之產品，將區分為銅牌、銀牌與金牌之評定等級，以作為供應商、通路商與消費者購買參考。

24. 電子產品環境評估工具(EPEAT)

25. 2. 原材料選擇 【3項必要準則：】 1. 除包裝及印刷電路板外，製造商應宣告塑料零部件是否含有超過5%的postconsumer再生塑膠。（宣告0~5%亦可） 2. 產品包裝除外，製造商應宣告用塑料零部件中是否含有超過5%的再生/可分解塑膠原料。（宣告0-5%亦可）  3. 產品包裝除外，製造商應宣告產品總重量(單位為磅) 

26. 2. 原材料選擇 【3項選擇性準則：】 1. 產品包裝除外，所有塑料產品應含平均至少10%再生/可分解塑膠原料 2. 印刷電路板除外，所有塑料產品應含平均至少25%的 postconsumer再生塑膠(postconsumer recycled plastic) 3. 印刷電路板除外，所有塑料產品應含平均至少10%的postconsumer再生塑膠(postconsumer recycled plastic) 註：Postconsumer plastic係指市面回收商所回收之塑料(非下腳料)

27. 取得EPEAT產品認證之品牌商/製造商

29. 購買EPEAT產品的環境績效 • 減少使用7550萬噸原物料，約等於5億8500萬台冰箱重量； • 滅少使用3220噸之有害物質(包括汞)，約等於160萬塊磚塊重量； • 減少使用的汞共可填滿482,381隻家用溫度計； • 減少產生124,000噸廢棄物，約等於6200萬塊磚塊重量；

30. 購買EPEAT產品的環境績效 • 另外，因為EPEAT要求註冊產品符合能源之星(Energy Star)規格，所以這些產品在其生命週期內也將減少能源耗用包括： • 減少420億度電，約為足夠提供370萬戶美國家庭使用1年的用電量； • 滅少1億7千400萬噸的氣體排放(包括溫室氣體)，並且減少36萬5000噸的廢水污染排放； • 減少331萬噸二氧化碳當量排放，約等於263萬台美國車輛的排放量

31. 美國聯邦政府增加通過EPEAT認證產品的購買量 於2009年1月，聯邦政府要求所有部門需購買已通過EPEAT認證的產品。 22個部門中的13個部門已經回報達到該要求，並且已經達到要求的標準，也就是95%採購的電腦、螢幕、筆記型電腦及其他電子產品，需通過EPEAT認證。為了達到該認證，電子產品必須通過嚴格的能源效率、有毒物質減量、回收性、包裝效率及其他環保標準的措施。 2009-05-22GreenBiz

32. 美國聯邦政府增加通過EPEAT認證產品的購買量 EPEAT標準係於2006年開始，目前已快速成長。除了聯邦政府的購買需求(1000件產品係由EPEAT於2008年12月認證)，2008年初，舊金山市也強制要求購買EPEAT的產品。 因為EPEAT的認證要求非常新且和其他IT要求需同時執行，因此需相當留意。聯邦政府也表示，各部門能符合採購95%EPEAT產品的標準，全都歸功於IT採購部門工作人員的貢獻及EPEAT系統的使用便利性。 2009-05-22GreenBiz

33. Amorphous vs. Crystalline?

34. Crystalline polymers in polymer field are semi-crystalline materials, which contain both amorphous and crystalline phases Crystalline Polymer • Properties dominated by both Tg and Tm • Semi-crystalline polymers can exhibit additional crystallization during heating or stretching Semi-Crystalline Polymer

35. Amorphous model：spaghetti or reptation theory

36. Amorphous model：spaghetti or reptation theory Reptation model is proposed by De Gennes. It is likely as a snake-like chain motion considering the movement of the tube can be achieved by the ability of the ends of the chain to randomly explore possible conformation. Reptation theory： No polymer contains more than 98% crystallinity at least 2% amorphous. Normally the crystalline polymer contain the crystallinity in the range of 40~60% called semi-crystalline.

37. The fringed micelle model First proposed model of semi-crystalline polymer：fringed micelle model crystallite interspersed in an amorphous matrix, partial polymer chain are regularly aligned parallel to each other. One region regular structure pass to another through amorphous region.

38. The fringed micelle model The fringed micelle model explain nicely the coexistence of crystalline and amorphous material in polymer, and also explain the increase in crystallinity that is observed when fiber is drawn. Morphology: generally consider at least 2 coexisting phases.

39. (a) (b) Figure 5.1 The fringed micelle model： (a) unoriented; (b) chains oriented by applied stress. ∵ Stretching the polymer oriented the polymer chain in the direction of the stress,increasing the alignment in the amorphous Areas and producing greater degrees of crystallinity. (Fig. 5.1b) ∵ Chains pass randomly from one crystallite to another no perfect crystallite in polymers. Crystallinity is similar to cross-linking in many feature, but cry-stallite will generally melt before the polymer degrade or solve in the solvent.

40. Crystallinity v.s mechanical properties WC ,ρ ρ hard & rigid ρ soft & sticky

41. } Imperfect fibril Amorphous Modified fringed micelle Paracrystalline Fringed lamellar Amorphous with correlation Old fringed micelle Crystal defects Schematic of Different Types of Order and Disorder in Oriented Polymers Ward, I.M., Hadley, D.W., An Introduction to the Mechanical Properties of Solid Polymers, John Wiley & Sons Ltd., New York, 1993, p.16.

42. DSC Technique Differential Scanning Calorimetry

43. What is DSC ? • A differential scanning calorimeter (DSC) measures the amount of energy absorbed or released by a sample as it is heated, cooled, or held at a constant temperature. • In a DSC a sample and a reference (often a piece of Indium metal) are contained in small aluminum pans with crimped tops. The pans are placed on individual heaters in a furnace in a nitrogen atmosphere. DSC ( Differential Scanning Calorimeter )

44. The furnace is heated and the temperature difference between the sample andreference is monitored so that the DSC can keep the temperatures the same. If an exothermic phase transition occurs, the temperature of the sample will tend to surge ahead of the reference. In this case the DSC doesn't need to furnish as much heat to the sample. If an endothermic transition occurs, the DSC must furnish more heat to the sample. The electrical power difference between the sample and reference measures the heat flow (dQ/dt) in the sample.

45. Thermal Analysis applications - DSC DSC • Principle: • Heat flow change vs. temperature • Measures: • Phase transition (Tg, Tm, Tc) and heat • Curing reaction and other chemical reactions

46. DSC operation

47. DSC operation

48. Tm Stress Relief Cold Crystallization DH Heat Flow Degradation Tg Start up Transient Curing Ordering Process Temperature Polymer Transitions

49. DSC Thermal Curve of PET 吸 熱 放 熱

50. Thermal curing studies • Detection of Tg • Onset of cure • Maximum rate of cure (peak maximum) • End of cure • Heat of cure