聚合物高压固相成型

1、聚合物成型加工技术聚合物成型加工技术（模具和装备）（模具和装备） PROCESSING TECHNOLOGIES OF POLYMERIC MATERIALS(MOULD AND EQUIPMENT)聚合物高压固相成型主讲人：吕 军西南交通大学材料科学与工程学院Telephone:-mail: &As for polymeric materials, the practical values of such mechanical properties as strength and modulus are much lower than those by th

2、eoretical prediction.Why? This is due to the intrinsic folded-chain conformation of macromolecules, as well as the asymmetric viscoplasticity, structure and geometry, resulting from traditional processing techniques.IntroductionModel of folded-chain crystalsExtended-chain crystals of polyethylene cr

3、ystallized on graphite substrate Solid phase forming under high pressure is a more effective route to produce polymer products with greatly improved physical and mechanical properties, achieved by creating the desired crystal morphologies with ideal molecular orientation during the processing. Low-t

4、emperature processing of baroplastics by pressure-induced flowJ.A. Gonzalez-Leon, et al: Nature Vol. 426 (2003), p. 424 &As a kind of equilibrium crystal with relative thermodynamic stable structure, polymer extended-chain crystals play an important role in the study on low dimensional physics,

5、and have potentials to find applications in functional components .PVDF piezo films Current problems of ECCSmall c-axis thicknessLong crystallization time for crystal growthAugust 2-6, 2010 Cairns, Australia Extended-chain lamellae of PE with 40-micron thickness, grown at 480MPa, 237 for 200hr A new

6、 methodology is particularly desirable!Triclinic structureOriginal PET: 527KSamples 1 and 2Sample 3Sample 4An illustration of disentanglement and chain extension through transesterificationstereo-open spherulites in PET samples crystallized at high pressureL.B. Li, et al, J Polym Sci B: Polym Phys 2

7、000, 38: 1612; Polymer 2001, 42: 2085; J Cryst Growth 2000, 216: 538.Sintering polymer nano-crystals at high pressureL.B. Li, et al, J Mater Sci Lett 2001, 20: 807.Original PEN: 565K; equilibrium melting temperature: 573K (by Buchner), 610K (by Cheng).PEN1PEN4PEN7PEN5PEN8PEN6 and 7L.B. Li, et al, Po

8、lymer 2001, 42: 8867. Growth of large polymer extended-chain single crystals High-quality synthetic polymer extended-chain single crystals with c-axis thickness exceeding 100 m were obtained within a relative short timeCrystallized at 200MPa, 623K for 6hrJ. Lu, et al: Macromol Rapid Commun Vol. 26 (

9、2005), p. 1478 AFMDSCMicro-FTIRMicro-RamanMicro-diffraction Growth MechanismWedge-shaped crystalsBent crystals Morphologies of extended-chain crystals with different characteristics were observed with SEM in the high-pressure crystallized PET/BAPC blendsJ. Lu, et al: J Polym Sci Pol Phys Vol. 44 (20

10、06), p. 3148 Wedge-shaped bent crystalExtended- and folded-chain crystalsS-profiled crystalsFormation process of large extended-chain crystalsWAXDDSCSample 2Sample 3Sample 2Sample 3Sample 2J. Lu, et al, J Macromol Sci B 2011, 50: 1018. Equilibrium melting point: 320 C (by Cheng)Fluctuation-assisted thickening