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Polymeric Matrix Composites (PMC)

Polymeric Matrix Composites (PMC). The reasons for PMC to be the most commonly used composites: monolithic polymer has low strength and stiffness processing is easier (no high temperature or pressure) Disadvantages of PMCs: low maximum working temperature high CTE, low dimensional stability

garrett-dickerson
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Polymeric Matrix Composites (PMC)

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  1. Polymeric Matrix Composites (PMC) The reasons for PMC to be the most commonly used composites: • monolithic polymer has low strength and stiffness • processing is easier (no high temperature or pressure) Disadvantages of PMCs: • low maximum working temperature • high CTE, low dimensional stability • sensitive to environmental factors: radiation, moisture,… e.g. water adsorption  degradation in strength, modulus  formation of internal stress  swelling  lowering of Tg • combustible for most polymers

  2. Classification of Polymers Thermosetting plastics (thermosets) amorphous Polymers Thermoplastics (partially) crystalline Rubbers (elastomers)

  3. Polymeric materials (Polymers) • mono•mer (mer = unit) • poly•mer

  4. Polymerization (聚合、聚化反應) Chain polymerization of monomers: (1)Initiation

  5. (2) Propagation R─CH2─CH2+CH2=CH2R─CH2─CH2─CH2─CH2 (3) Termination R(CH2─CH2)m+R´(CH2─CH2)n R(CH2─CH2)m─ (CH2─CH2)nR´

  6. Degree of Polymerization (DP) DP = the number of subunits or mers in the polymer molecular chain =

  7. Homopolymer (同聚合體) & Copolymer(共聚合體) • Copolymers: • Random copolymers. Different monomers are randomly arranged within the polymer chains. If A and B are different monomers, then an arrangement might be AABABBBBAABABAAB… (Fig 7.8a) • Alternating copolymers. Different monomers show a definite ordered alternation, as ABABABABABAB… (Fig 7.8b) • Block copolymers. Different monomers in the chain are arranged in relatively long blocks of each monomer: AAAAA─BBBBB─… (Fig 7.8c) • Graft copolymers. Appendages of one type of monomer are grafted to the long chain of another: AAAAAAAAAAAAAAAAAAAAA (Fig 7.8d) B B B B B B

  8. Copolymer Arrangements

  9. Stepwise polymerization • Stepwise polymerization: (condensation polyerimization reaction)

  10. Network polymerization

  11. Industrial Polymerization Methods

  12. Partial Crystalline Thermoplastics

  13. Structure of spherulite

  14. Temperature Effect on Polymers

  15. Glass Transition Temperature, Tg

  16. Commercial Thermoplastics • Polyethylene (PE) 特點：價格低、室溫下韌性佳、低溫下保有強度、曲撓性腐蝕抵抗佳、絕緣性佳、無臭無味、低水汽穿透性 應用：容器、電絕緣材料、瓶子、薄膜

  17. Commercial Thermoplastics • Polyvinyl Chloride (PVC) 特點：高強度、脆性、中等熱變形溫度、介電性質佳、溶劑抵抗力強、防火防蝕 應用：汽車內裝、雨衣、鞋、家中用品另件

  18. Commercial Thermoplastics • Polypropylene (PP) 特點：抗化學、水分及熱之能力佳，適當之表面硬度、形狀尺寸之穩定性佳、優越之彎曲壽命、價格低 應用：瓶罐、電瓶外殼、汽車風扇罩、導管、包裝袋、薄膜

  19. Commercial Thermoplastics • Polystyrene (PS) 特點：堅硬、透明、容易加工處理、脆性、尺寸穩定性佳、模鑄，收縮低、抗侯性佳、易受溶劑浸蝕 應用：汽車內部零件、家電用品外殼、轉盤旋鈕

  20. Commercial Thermoplastics • Polyacrylonitrile (PAN) 特點：形成高強度纖維，可抵抗水分及溶劑之浸蝕 應用：運動衫、毛毯之纖維

  21. Commercial Thermoplastics • Polymethyl methacrylate (PMMA) 特點：堅硬、強度高、可見光穿透性高、室外環境之化學抵抗佳，俗名壓克力(acrylics) 應用：窗戶玻璃、廣告看板、護目鏡

  22. Commercial Thermoplastics • ABS 特點：抗熱與化學性佳、韌性佳、表面光澤、剛性佳、易加工處理 應用：管線及其配件、電腦外殼、電話外殼

  23. Commercial Thermoplastics • Polytetrafluoroethylene (PTFE) 特點：極緻密之結晶材料、高密度、可抗有機溶劑浸蝕、超低溫至高溫之機械性質佳、高衝擊強度、極低摩擦係數、強度低 應用：管路、幫浦零件、不沾粘之覆層

  24. Commercial Thermoplastics • Polychlorotrifluoroethylene (PCTFE) 特點：結晶度較低、易壓模製造 應用：O型環

  25. Engineering Thermoplastics • Polyamides (Nylons) [聚醯胺(尼龍)] 特點：高度結晶性構造、高強度、高熱變形溫度、化學抵抗性佳、易加工處理、高潤滑性、低表面摩擦、抗磨耗性佳、吸水性強造成尺寸改變 應用：無潤滑之齒輪、軸承、汽車計速器之齒輪

  26. Engineering Thermoplastics • Polyamides (Nylons) [聚醯胺(尼龍)]

  27. Engineering Thermoplastics • Polycarbonate (PC) (聚碳酸酯) 特點：高強度、高衝擊強度、熱變形溫度高、電絕緣性佳、透明、潛變抵抗佳、抗化學腐蝕、尺寸穩定性優 應用：安全玻璃、凸輪、齒輪、安全帽、紅綠燈罩及鏡片、太陽能板之玻璃

  28. Engineering Thermoplastics • Phenylene Oxide-Based Resin(苯氧基樹脂) 特點：高剛性、高強度、尺寸穩定性佳、低潛變、低水分吸收性、良好之介電性質、優良之衝擊抵抗 應用：汽車儀表板、柵板、小家電外殼

  29. Engineering Thermoplastics • Acetals (聚縮醛) 特點：高強度、熱變形溫度高、長期承載性佳、尺寸穩定性佳、低摩耗、低摩擦、疲勞抵抗佳 應用：汽車安全帶及窗戶把手另件、幫浦翼輪、寫字用筆

  30. Engineering Thermoplastics • Thermoplastic Polyesters (熱塑性聚酯) 特點：具結晶性、強度佳、低水分吸收性、化學抵抗佳、電絕緣性優 應用：幫浦翼輪、流量計、點火線圈蓋、噴油控制管

  31. Engineering Thermoplastics • Polysulfones (聚砜塑膠) 特點：高強度、高剛性、高衝擊強度、高氧化穩定性、高熱變形溫度、低潛變、可抵抗水解作用 應用：電容器薄膜、醫學器皿

  32. Engineering Thermoplastics • Polyphenylene Sulfide (聚苯硫) 特點：堅硬、高強度、具結晶性、高化學侵蝕抵抗、高溫之強度保持性佳、低鑄模收縮 應用：汽車排氣污染控制系統另件、油田之管路及配件

  33. Engineering Thermoplastics • Polyetherimide (聚醚醯亞胺) 特點：熱抵抗性高、融溶下流動性佳、電絕緣性優 應用：斷電器外殼、印刷電路板

  34. Thermosetting Plastics (Thermosets) • Epoxy Resins (環氧樹脂) 特點：液態時低分子量、製程處理時流動性佳、浸濕能力強、硬度高、強度大、化學抵抗強、硬化收縮低 應用：罐頭之裡襯、電纜之表層、高壓電絕緣體、複合材料

  35. Thermosetting Plastics (Thermosets) • Epoxide group (環氧基群) • Epoxy resin chain Be: benzene ring (苯環)

  36. Thermosetting Plastics (Thermosets) • Curing (cross-linking) of epoxy resin:

  37. Thermosetting Plastics (Thermosets) • Unsaturated Polyesters (未飽和聚酯) 特點：低粘滯性、可填充大量強化材料、填充後強度高、衝擊及化學抵抗力強 應用：汽車面板、浴室用品 Ester linkage :

  38. Thermosetting Plastics (Thermosets) • Linear polyester • Curing (cross-linking) of polyester

  39. Properties of General-Purpose Thermoplastics

  40. Properties of Engineering Thermoplastics

  41. Properties of Thermoset Plastics

  42. Deformation mechanisms in polymeric materials • Extension of main carbon chain (elastic) • Uncoiling of main carbon chain ( elastic & plastic) • Chain slippage (plastic)

  43. Plastic Yielding of Thermoplastic Materials

  44. Strengthening of Thermoplastics • Strengthening due to the average molecular mass of the polymer chains Polymer polymerization: low molecular mass → high molecular mass liquid → solid

  45. Strengthening of Thermoplastics • Strengthening by increasing the amount of crystallinity in a thermoplastic material e.g.: Low-density polyethylene High-density polyethylene

  46. Strengthening of Thermoplastics • Strengthening thermoplastics by introducing pendant atomic group on the main carbon chains Example: polypropylene: P.E.→ P.P. polystyrene: P.E.→ P.S.

  47. Strengthening of Thermoplastics • Strengthening thermoplastics by bonding highly polar atoms on the main carbon chain Example: Polyvinyl chloride: P.E.→ PVC

  48. Strengthening of Thermoplastics • Strengthening thermoplastics by the introduction of oxygen and nitrogen atoms in the main carbon chain Example: Polyoxy methylene (acetal): P.E.→ acetal Polyamide (nylon 6,6): P.E.→ nylon 6,6

  49. Strengthening of Thermoplastics • Strengthening thermoplastics by introducing phenylene rings into the main polymer chain in combination with other elements such as O, N and S in the main chain Example: P.E.→ thermoplastic polyester P.E.→ polycarbonate

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