本實驗主要觀察PLLA微變形區之表貌微觀結構，研究其受力變形的基本機制。觀察發現，在原子力顯微鏡（AFM）下，PLLA薄膜乃由密佈的微小lamellae所覆蓋，顯示PLLA薄膜是由細碎的微小晶粒與非晶態（amorphous）區域所組成，但是craze的成核則總是由非晶質區域開始。依據不同的製程，結晶度可以控制craze成長的寬度。然而當lamellae被拉伸進入craze會被解構，形成鏈狀結構。當結晶度提高時則會限制craze成長的寬度。90℃水解對PLLA薄膜則會有兩種顯著的影響，水解初期會有在結晶的效應，到水解後期水解會使薄膜產生孔洞進而降低PLLA的機械性質。
PHA因為其Tg在零度附近，使得PHA薄膜拉伸時高分子可坐大規模的運動形成寬大的craze，但是因為其是共聚合物，因為溶劑的差別溶解度的關係，薄膜表面佈滿孔洞，這些孔洞進而使PHA薄膜形成craze後容易在孔洞形成破裂。

Poly(L-lactic acid)（PLLA）is biodegradable and biocompatible polymer extensively used in bone fixation, drug delivery, and tissue engineering. The purpose of this study attempted to find the mechanical properties by PLLA thin film stretched. It was revealed that there is distinctive nano-mechanical behavior. First, crystallites disperse in PLLA thin film which was observed by atomic force microscope（AFM）and nucleation of crazes is always in the amorphous region between crystallites. Crystallinity could control craze widening, and it depends on PLLA films preparation. In low crystallinity, as strain increases, crystallites deform slightly and some of them were probed in crazes. As crazes growth most crystallites arrangement in crazes is parallel to stretching direction to form chain structure. This chain structure seems due to lamella cleavage arises from stress induced local melting. Violently, high crystallinity limits crazes width almost under 2μm which is smaller than in low crystallite density. The growth of craze sometimes is by small crazes merged together and PLLA film is very though showing no micro fracture at large strains beyond 20％. After stretched, crystallites outside of crazes region deform slightly which was intra-lamellae slip, but the amorphous region is the major deformation region. The craze formation was amorphous dominated but lamellae limit craze extend.

1. Ray E. Drumright；Patrick R. Gruber；David E. Henton, Adv. Mater. 2000, 12, No. 23, December 1
2. J.W.Leenslag；A.J.Penning；R.R.M.Bos；F.R.Rozema；G.Boering, Biomaterials. 8, 311.(1987)
3. T.Nakamura；S.Hitomi；S.Watanabe；Y.Shimizu；K.Jameshidi；S.H.Hyon；Y.Ikada, J.Biomed.Mater.Res.,207, 290(1989)
4. De Santis；P. Kovacs, Biopolymers. 6, 299-306(1968)
5. Eling, B.; Gogolewski, S.; Pennings, A. J. Polymer 1982, 23, 1587. W. Hoogsteen, A. R. Postema, A. J. Pennings, and G. ten Brinke, Macromolecules 1990,23, 634-642
6. Kobayashi, J., T., Ichiki, M., Oikawa, A., Suzuki, H., Watanabe, T., Fukada, E., Shikinami, Y. J., Appl. Phys. 77 (7), 1 April 1995
7. B. Kalb, A. J. Pennings, POLYMER, 1980, Vol 21, June 607
8. Tadakazu Miyata” and Toru Masukot,Polymer Vol. 38 No. 16, pp. 4003-4009, 1997
9. Tadahisa Iwata and Yoshiharu Doi, Macromolecules 1998, 31, 2461-2467
10. S. Li；M. Vert, ”Global Chinese Symposium on Biomaterials and Controlled Release“ ,1999, 333.
11. M. Singh；A. Singh；G.P. Talwar, Pharm. Res., 1991, 8, 958
12. Y. Kimura；Y. Matsuzaki；H. Yamane；T. Kitao, Polymer, 1989, 30, 1342
13. F.G. Hutchinson；B.J.A. Furr, Biochem. Soc. Trans., 1985, 13, 520
14. L.M. Sanders；G.I. McRae；K.M. Vitale；B.A. Kell, J. Controlled Release, 1985, 2, 187.
15. R.A. Kenley；M.O. Lee；T.R. Mahoney；L.M. Sanders, Macromolecules, 1987, 20, 2398.
16. J.M. Schakenraad et al., J. Biomed. Mater. Res., 1989, 23,1271.
17. J. Helder；P.J. Dijkstra；J. Feijen, J. Biomed. Mater. Res., 1990, 24, 1005.
18. S. Cohen et al., Pharm. Res., 1991,8, 713.
19. C.G. Pitt et al., Biomaterials, 1981, 2, 215
20. C.G. Pitt,“Biodegradable Polymers and Plastics“, 1992, M. Vert et al. eds.,Royal Society of Chemistry, Lodon, 7.
21. S. Li；H. Garreau；M. Vert, J. Mater. Sci.:Mater. Med., 1990, 1, 123.
22. K.R. Huffman；D.J. Casey, J. Polym. Sci.:Polym. Chem. Ed., 1985,23, 1939.
23. S. Li；H. Garreau；M. Vert, J. Mater. Sci.:<ater. Med., 1990, 1, 131
24. S. Li；H. Garreau；M. Vert, J. Mater. Sci.:<ater. Med., 1990, 1, 198
25. M. Vert；S. Li；H. Garreau, J. Controlled Release, 1991,16,15.
26. M. Therin et al., Biomaterials, 1992, 13, 594.
27. M. Vert；S. Li.；H. Garreau, Clin. Mater., 1992, 10, 3.
28. S. Li.；M. Vert, Macromolecules, 1994, 33, 37.
29. R.K. Kulkarni；E.G. Moore；A.F. Hegyeli；F. Leonard, J. Biomed. Mater. Res., 1971, 30, 344
30. L. Getter；D.E. Cutright；S.N. Bhaskar；J.K. Augsburg, J. Oral Surg., 1972, 30, 344.
31. J.M. Brady；D.E. Cutright；R.A. Miller；G.C. Battistone, J. Biomed. Mater. Res., 1973, 7, 155.
32. D.E. Cutright；J.D. Beasley；W.J. Larson；W.R. Posey, Oral Surg., 1974, 37, 142.
33. C.G. Pitt；M.M. Gratzl；G.L. Kimmel；J. Surels；A. Schindler, Biomaterials, 1981, 2, 215.
34. J.O. Hollinger；G.C. Battistone, Clin. Orthop., 1986, 207, 290
35. J.W. Leenslag；A.J. Penning；R.R.M. Bos；F.R. Rozema；G. Boering, Biomaterials, 1987, 8,311
36. T. Nakamura；S. Hitomi；S. Watanabe；Y. Shimizu；K. Jameshidi；S.H. Hyon；Y. Ikada, J. Biomed. Mater. Res., 1989, 23, 1115
37. Y. Matsusue；T. Yamamuro；M. Oka；Y. Ikada；S.H. Hyon；Y. Shikinami, J. Appl. Biomater., 1991,2,1.
38. Robert W. Lenz and Robert H. Marchessault (2005), Bacterial Polyesters: Biosynthesis, Biodegradable Plastics and Biotechnology, Biomacromolecules , v.6 , P. 1~8
39. Markus Potter and Alexander Steinbuchel (2005), Biomacromolecules, v.6 , P. 552~560
40. Jumpei Kawada, Tina Lu¨tke-Eversloh, Alexander Steinbu¨ chel, and Robert H. Marchessault (2003), Biomacromolecules, v.4 , P. 1698~1702
41. M. AVELLA, E. MARTUSCELLI, M. RAIMO (2000), JOURNAL OF MATERIALS SCIENCE , v.35 , P. 523~545
42. C.S.K. Reddy, R. Ghai, Rashmi, V.C. Kalia (2003), Bioresource Technology , v.87 , P. 137~146
43. L. Jurasek and R. H. Marchessault (2002), Biomacromolecules, v.3 , P. 256~261
44. Colin W. Pouton , Saghir Akhtar (1996), Advanced Drug Delivery Review, v.18 , P. 133~162
45. Dieter Jendrossek (2005), Biomacromolecules , v.6 , P. 598~603
46. Manfred Zinn, Bernard Witholt, Thomas Egli (2001), Advanced Drug Delivery Reviews, v.53 , P. 5~21
47. Guocheng Du and Jian Yu (2002), Environmental Science & Technology, v.36 , P. 5511~5516
48. Kramer, E. J.; Berger, L. L. Adv. Polym. Sci. 1990, 91/92,1.
49. Lin, J.–H.; Yang, A. C.–M., Macromolecules 2001, 34, 4865.
50. Kramer, E. J. Adv. polym. Sci., 1983, 52/53, 1.
51. Gent, A. N. In The Mechanics of fracture, AMD; Erdogon, F., Ed.; ASME: New York, 1976, 19, 55
52. Yang, A. C.-M.; Kramer, E. J. J. Polym. Sci., Polym. Phys. Ed. 1985, 23, 1353.
53. Yang, A. C.-M.; Kramer, E. J.; Kuo, C. C.; Phoenix, S. L. Macromolecules, 1986, 19, 2010.
54. Yang, A. C.-M.; Kramer, E. J.; Kuo, C. C.; Phoenix, S. L. Macromolecules, 1986, 19, 2020.
55. B.D. Lauterwasser；E.J. Kramer, Philos. Mag., 1979, A245, 312