งานนำเสนอกำลังจะดาวน์โหลด โปรดรอ

งานนำเสนอกำลังจะดาวน์โหลด โปรดรอ

1.Addition-Condensation system 1.1 Addition polymerization ( แบบการเติม ) 1.2 Condensation polymerization ( แบบ ควบแน่น ) 2.Chain growth-Step Growth System.

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งานนำเสนอเรื่อง: "1.Addition-Condensation system 1.1 Addition polymerization ( แบบการเติม ) 1.2 Condensation polymerization ( แบบ ควบแน่น ) 2.Chain growth-Step Growth System."— ใบสำเนางานนำเสนอ:

1 1.Addition-Condensation system 1.1 Addition polymerization ( แบบการเติม ) 1.2 Condensation polymerization ( แบบ ควบแน่น ) 2.Chain growth-Step Growth System 2.1 Chain growth polymerization ( แบบ ลูกโซ่ ) 2.2 Step growth polymerization ( แบบขั้น ) Classification(3): polymerization methods

2 1.2 Condensation polymerization ( แบบควบแน่น ) Part of the monomer molecule is kicked out when the monomer becomes part pf the polymer. The part that gets kicked out is usually a small molecule like water (H 2 O), or HCl gas 1.1 Addition polymerization ( แบบการเติม ) 1. Addition-Condensation system Monomer molecules become part of the polymer without kicking any molecules out.

3 2. Chain Growth-Step Growth System monomers become part of the polymer one at a time. 2.1 Chain growth polymerization ( แบบลูกโซ่ )

4 2.2 Step growth polymerization ( แบบขั้น ) monomer + monomer = dimer dimer + monomer = trimer dimer + dimer = tetramer trimer + dimer = pentamer n-mer + m-mer = (n+m)mer or Two short chains can react to form longer chain

5 Chain-Growth ( or addition) polymerization

6 n n monomerpolymer C = C H HH H C H H H H n When ethylene is polymerized to make polyethylene, the every atom of the ethylene molecule becomes part of the polymer (none gained, none lost) Ethylene Polyethylene Example:

7 In General; Addition Polymerization = Chain Growth Polymerization - do not give off by product - monomers become part of the polymer one at a time ประกอบด้วยขั้นตอนต่างๆ 3 ขั้นตอน และมีการ ใช้สารเคมี 2 ชนิด 1. initiation ขั้นเริ่มต้นปฏิกิริยา 1. monomer 2. Prapagation ขั้นดำเนินไปของปฏิกิริยา 2. initiator 3. termination ขั้นสิ้นสุดปฏิกิริยา Free radical Anionic - Cationic +

8 1.Monomer –Becomes repeating units in polymer chains –Monomer need to have at least 1double bond 2.Initiator - add into monomer to activate joining of monomers into long polymer chains Functions of the 2 basic chemicals

9 There are 3 types of chain growth polymerizations: Free radical polymerization (Free radical initiator I  ) Anionic polymerization (Anionic initiator I-) Cationic polymerisation (Cationic initiator I+) (names depend on type of initiator)

10 Free radical polymerization Initiator peroxide (ROOR, HOOH) Azo compound (-N=N-) easily decompose into 2 free radicals when exposed to heat H 3 C – C CH 3 CN N + + C - CH 3 CH 3 CN C – O – O - C O O + O C – O O - C O O C – O O C O + H 3 C – C – N = N – C - CH 3 CH 3 CN

11 1. Initiation step Free radical จะกระตุ้นให้พันธะคู่ในโมโนเมอร์แตกออก แล้วเกิดพันธะใหม่ขึ้น C = C H HH H C H H H H

12 2. Propagation Step Free radical ที่ปลายจะไปกระตุ้น monomer ตัวที่อยู่ใกล้คียงให้ พันธะคู่แตกออก Monomer ตัวที่เหลือจะเข้าต่อที่ปลายในลักษณะเดียวกันไปเรื่อยๆ C H H H H C = C H HH H C H H H H H H H H H H H H n

13 ขั้นการสิ้นสุดของปฏิกิริยา มี 3 แบบ : 1. Coupling: M x + M y M x+y 2. Disproportionation: M x + M y M x + M y-1 3. Chain transfer agent: 3. ขั้นสิ้นสุดปฏิกิริยา (Termination step) -C = C H H C H H + Cl – C – Cl Cl C – Cl H H + Cl – C Cl Initiate another chain

14 Anionic polymerization (I-) Initiator CH3 – CH2 – CH2 – CH2 - Li butyl lithium CH 3 – CH 2 – CH 2 – C + Li + CH 3 – CH 2 – CH 2 – CH 2 - Li H H -

15 1. ขั้นเริ่มต้นปฏิกิริยา (Initiation step I-) CH 3 – CH 2 – CH 2 – C Li + H H - C = C H HH H CH 3 – CH 2 – CH 2 – CH 2 - C Li + H H -

16 2. ขั้นดำเนินไปของปฏิกิริยา (Propagation Step II.) CH 3 – CH 2 – CH 2 – CH 2 - C Li + H H - + C = C H HH H CH 3 – CH 2 – CH 2 – CH 2 - C – C – C Li + H H - HH HH C H H H H n -

17 Living anionic polymerization Living polystyrene butadiene Living styrene-butadiene block copolymer Here A stands for the initiator fragment end groups. Sometimes it’s a butyl group from butyl lithium, sometimes it isn’t. - A – A – A – A – A – A – A – A – B – B – B – B – B – B – B - B Block copolymer

18 Cationic polymerisation (I+)

19 1. ขั้นเริ่มต้นปฏิกิริยา (Initiation step I+) Initiator: AlCl 3 /H 2 O AlCl 3 /H 2 O

20 2. ขั้นดำเนินไปของปฏิกิริยา (Propagation Step) n

21 Step-Growth (Condensation) Polymerization

22 In General; Condensation Polymerization = Step Growth Polymerization - give off by product - monomers become part of the polymer one at a time or two short chain react to form longer chain

23 H + H 2 O acid alcoholester เอสเทอร์ริฟิเคชัน (esterification)

24 monomer ที่ใช้ต้องมีหมู่ฟังก์ชันอย่าง น้อย 2 หมู่ diaciddial polyester

25 PET +n H 2 O

26 The first thing the two monomers will react to form a dimer. Terapheyl chloride Ethylene glycol ester dimer

27 2-mer + 2-mer = 4-mer + HCl monomer + monomer = 2-mer 2-mer + monomer = 3-mer 2-mer + 2-mer = 4-mer 3-mer + dimer = 5-mer n-mer + m-mer = (n+m)mer

28 Nylon 6,6 This Cl atom and this H atom don’t end up in the polymer, they split off to form HCl gas. + N-CH 2 -CH 2 -CH 2 -CH 2 -CH 2 -CH 2 -N H H H H Cl-C-CH 2 -CH 2 -CH 2 -CH 2 -C-Cl O O nylon 6,6 adipoyl chloride hexamethylene diamine HCl + C-CH 2 -CH 2 -CH 2 -CH 2 -C- O O N-CH 2 -CH 2 -CH 2 -CH 2 -CH 2 -CH 2 -N H H n

29 In a condensation polymerization, some atoms of the monomer don’t end up in the polymer. HCl + C-CH 2 -CH 2 -CH 2 -CH 2 -C- O O N-CH 2 -CH 2 -CH 2 -CH 2 -CH 2 -CH 2 -N H H n When nylon 6,6 is made from adipoyl chloride and hexamethylene diamine, the chlorine atoms from the adipoyl chloride, each along with one of the amine hydrogen atoms, are expelled in the form of HCl gas. + N-CH 2 -CH 2 -CH 2 -CH 2 -CH 2 -CH 2 -N H H H H Cl-C-CH 2 -CH 2 -CH 2 -CH 2 -C-Cl O O

30 One example is the polymerization which produces polyurethane. There are also addition polymerization which are step growth polymerizations. Isocyanate groups a diisocyanatea diol Not only monomers react, but also dimers, trimer, and so on. This makes it a step growth polymerization. Also, because no small molecule by-products are produced, it is an addition polymerization. เอกสารประกอบจาก ดร. ธนาวดี ลี้จากภัย MTEC

31 Conclusion Chain growth polymerization: generally = addition polymerization : monomer become part of the polymer one at a time. –Polymer chain grows rapidly to a long size as soon as the initiation step starts. –High molecular weight polymer is formed immediately. –monomer concentration decreases as the number of high polymer molecules increase –the reaction mixture contains-monomer, high- molecular weight polymer, growing chain

32 Step growth polymerization: generally = condensation polymerization : Two short chains can react to form longer chain. –monomer disappears much faster –molecular weight increase through out the course of the reaction –high molecular weight polymer is not obtained until the end of the reaction Conclusion

33 Ref: S.L. Rosen, John Wiley & Sons 1993

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38 Classification(4): Architecture of Chain Each structures respond to solvents differently. Linear and Branched Polymers – can be soluble in suitable solvents Linear polymers Branched polymers HDPE LDPE LLDPE

39 Crosslink polymers –Heavily crosslinked  not soluble and not swell ex. Ebonite bowling ball – no swelling –Lightly crosslinked  not soluble but swell in solvent

40 Classification(5): Number of repeating unit present in the polymer chains homopolymer (PE, PP, PS, PVC, PMMA, PC, PET), copolymer (SBR, NBR), terpolymer (ABS)

41 Different types of copolymers —xoxoxoxoxoxoxo— Alternating copolymer —xxoooxoxooxxxox— Random copolymer —xxxxxooooooxxxx— Block copolymer Graft copolymer

42 โคโพลิเมอร์ที่มีคาร์บอนเป็นโครงสร้างหลัก (Ref: A. Kumar and R.K. Gupta, McGraw-Hill 1998)

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44 Classification(6): orientation of polymer chains (Morphology) Amorphous Semi-crystalline

45 Polymer Thermoplastic Elastomer Thermoset Semi-Crystalline Amorphous ( lightly cross linked) (heavily cross linked ) Network Cross linked polymers Linear/branched polymers (no cross linked)

46 T % crystallinity ~70% Tg Tm Viscous melt Hard&Strong Brittle rubbery Leathery ductile

47 Influence of molecular weight on properties of polymers ( Ref: A. Kumar and R.K. Gupta, McGraw-Hill 1998)

48 Chapter 4: Orientations and Crystallinity of Polymers

49 Orientation of Polymer Chains 1.Connection of chain (Configurational features) - Geometric details of how each repeat unit adds to the growing chain - Occur during polymerization process (cannot change by rotation) 2.Rotation and twisting of chain (Conformation) - rotation of backbone or side group

50 Factors affecting Crystallinity of Polymers Factors that affect properties of polymers 1.Architectural features 2.MW and MWD 3.Configurational features 4.Stereoregularity (conformation) 1.Architectural features: -Branching -Cross linking -Nature of copolymer

51 2. Molecular weight (MW), Molecular Weight Distribution (MWD): Polymers with long chain and narrow molecular weigth distribution  more crystallinity High MW Low MWD Easily crystallized

52 3.Configurations: Geometric details of how each repeat unit adds to the growing chain  affect properties of polymers - Head to Head - Head to Tail (normal arrangement) - Tail to Tail “Head to tail” “Head to Head”/“Tail to Tail” Configuration: cannot be changed by rotation of the backbone.

53 4. Stereoregularity—rotation around the backbone Rotation of C n -C n+1 bond Gauche positive (g+) Trans (t) [lowest potential energy—most probable] Gauche negative (g - ) Cis-Tran Isomer for C=C Trans conformation: all backbones lie in the same plane-planar zigzag plane - Rotation of side group - isotactic - syndiotactic - atactic (Ref: A. Kumar and R.K. Gupta, McGraw-Hill 1998) (rotation of backbone or side groups) - Rotation of backbone

54 Gauche positive (g+) Trans (t) Gauche negative (g - ) potential energy of each conformation Trans conformation (Ref: A. Kumar and R.K. Gupta, McGraw-Hill 1998) Rotation of C n -C n+1 bond

55 Cis-Trans Isomer (Rotation of C n =C n+1 bond) Poly (cis-1,4-isoprene) Poly (trans-1,4-isoprene)

56 Rotation of side groups (Stereoisomerism) Ex. Repeat unit.

57 Ref.: L.H. Sperling, John Wiley & Sons, Inc. (1992)

58 Requirement for crystallinity –Need ordered regular chain structure (syndiotactic+isotactic) –The 2 nd forces holding chains > disorder effect of thermal energy “Anything that reduces the regularity of backbone reduces the crystallinity.” Ex. PE, PP are crystalline polymers  copolymer of PP/PE is amorphous “There is no complete crystalline polymers” % crystallinity – show fraction of crystal structure inside polymers

59 1. The Fringed Micelle Model 2. Folded-Chain model Models for Crystal Formation

60 3. Folded-Chain model Tie molecules

61 Crystal Growth Ref.: L.H. Sperling, John Wiley & Sons, Inc. (1992)

62 Steps of Spherulite Formation

63 Spherulite (cont.) Ref: R.J. Young and P.A. Lovell, Chapman&Hall 1991

64 Spherulites Spherulites grow radially from a point of nucleation until other spherulites are encountered.

65 XRD patterns of Amorphous and Semi- crystalline Polymers Ref: R.J. Young and P.A. Lovell, Chapman&Hall 1991

66 Size: size of spherulites can be controlled by the number of nuclei present. (normally dia. ~ 0.01 mm) No. Nucleation siteSize of spherulites How to enhance transparency and reduce brittleness? Add nucleating agents Quench polymers (increases nucleation sites) or Spherulite (cont.)

67 Effect of Crystallinity on Mechanical Properties more crystallites   –Ex:  (density) > > branching < < % crystalline > > Degree of crystallinity: สมการ amorphous + crystalline Branching: more branching  less crystallinity HDPELLDPELDPE

68 Tacticity  crystallinity  optical properties Atactic -->mostly  Amorphous polymers  transparent Isotactic mostly crystalline polymers Syndiotactic  /refractive index of phase amorphous = phase crystalline  transparent Ex1: Foam ex. Foamed PS  เป็นสีขาวทึบเพราะแสงผ่านเฟส PS และ gas bubbles Ex2: high-impact PS  เป็น PS ที่มีอนุภาค polybutadiene rubber ขนาด 1-10  m. กระจายอยู่ใน amorphous PS Size of crystallites < wavelength of visible light  transparent Low degree of crystallinity  fairly transparent

69 Effect of crystallinity on optical properties Basic concept: เมื่อขนาดของอีกเฟสหนึ่งมีขนาด ใหญ่กว่า light passes btw. two phases ความยาวคลื่นของแสง  เกิดการหัก เห  ทึบแสง w/ different refractive indices เมื่อขนาดของอีกเฟสหนึ่งมีขนาด เล็กกว่า ความยาวคลื่นของแสง  ไม่เกิดการ หักเห  โปร่งแสง Light Passes through Light scatters.

70 Liquid Crystalline Polymers Molecules that show a degree of order in the liq. Phase –If liq. Phase is solution  lyotropic LCP –If liq. Phase is melt  thermotropic LCP is self reinforced composite Ex. (lyotropic) Kevlar เป็น aromatic polyamid (“aramid”) with repeating unit pull into fibers in the solution of H 2 SO 4 use for bullet-proof vests ( เสื้อเกราะกันกระสุน )

71 Ex. (thermotropic LCP) Note: liq. Crystalline polymers have highly aromatic backbone  inhibit rotation  stiff, rigid extended chain Xydar Vectra

72 Extended chain crystal When pulled  polymer will align in the flow direction  crystallize (extended chain crystal) (the more you pull, the stronger it becomes)

73 Stretching Curve and Crystal Orientation

74 Crystal Orientation with Stretching

75 XRD ring with Stretching


ดาวน์โหลด ppt 1.Addition-Condensation system 1.1 Addition polymerization ( แบบการเติม ) 1.2 Condensation polymerization ( แบบ ควบแน่น ) 2.Chain growth-Step Growth System.

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