厚热塑性复合材料AS4/PEEK角铺设层合板的层间应力分析

将表征热塑性复合材料AS4 /PEEK非线性行为和应变速率相关行为的三维弹塑性模型通过程序加以实现。将程序计算结果和文献实验结果相比较可以发现,二者吻合较好,验证了所生成程序的有效性。计算了厚的AS4 /PEEK角铺设层合板[±25]s4在不同界面上的层间应力。由层间应力的三维分布图,分析了不同界面上层间应力的分布特征,并说明了可能引起层间分层的主要因素。     

Solvent-induced crystallinity in poly(aryl-ether-ether-ketone) [PEEK]

The amount and structure of the crystals formed by the solvent-induced crystallization (SIC) following a sorption-desorption cycle of five fluids (benzene, toluene, chloroform, methylene chloride, and carbon disulfide) in amorphous PEEK was determined by wideangle x-ray scattering (WAXS). The SIC crystal structure was compared with that produced by thermal methods, both those formed at low temperature by heating the amorphous material 10–20°C above T_g or by cooling from the melt. Although smaller in size, the SIC crystals are tighter and more organized than those produced thermally. The WAXS data indicates that all five fluids produce approximately 35% crystallinity in PEEK. Gravimetric data suggest that a low-density region, consisting of either microvoids or highly disordered amorphous region, surrounds the crystals.     

Melting behavior of poly(ether ether ketone) in its blends with poly(ether imide)

We detail the melting behavior of poly(ether ether ketone) (PEEK) and investigate its melting behavior in miscible blends with poly(ether imide) (PEI). The determination of the equilibrium melting point (T_m⁰) of PEEK is discussed by considering its inhomogeneous morphology. T_m⁰ is obtained by a long extrapolation of a Hoffman–Weeks plot to 384°C. Hindrance of PEEK crystal reorganization induced by PEI during heating is observed over the blend composition investigated (20–75 wt % PEEK). This behavior is correlated with the incorporation of PEI in the interlamellar zones of PEEK crystals. The interaction parameter χ of PEEK/PEI blends is estimated by the equilibrium melting point depression. This gives the interaction density B = ?1.2 cal/cm³, and x = ?0.40 at 400°C. © 1993 John Wiley & Sons, Inc.     

含二联苯结构聚醚醚酮的微结构及磺化改性的性质研究

本文利用ＰＥＥＫ的ＡＭ１条件优化结果，并结合二联苯结构与不含二联苯结构聚醚醚酮的结构相似性，确定了含二联苯结构聚醚醚酮重复单元的最优构型，据此给出了此分子链的微观构型。在实验上也研究了磺化改性对此聚合物红外光谱的影响。     

EFFECT OF ANNEALING TREATMENTS ON DEFORMED POLY-ETHER-ETHER-KETONE (PEEK) FILMS

Physical aging of tapes of poly-ether-ether-ketone (PEEK) drawn at 120°C to 150% elongation and aged for 2 months at room temperature and at 120°C was analyzed. The physical aging was followed mainly with thermal analysis, transport properties, and Young's modulus. Moreover, a mechanical analysis, consisting of checking the length of tapes subjected to a constant load, during a thermal run gives additional information on the aging and on the capability to crystallize. The results are consistent with the formation on small regions in which segments of chains are closely packed.     

Analysis of crystallization kinetics of poly(ether ether ketone)

An optical microscope equipped with a video photograph system was used to follow the growth of spherulites. Under nitrogen atmosphere, the growth rates at 290 and 300°C suggest that when the melt of PEEK has been equilibrated for 15 min at 400°C, the subsequent crystallization behavior was nearly independent of the prior thermal history. Linear growth rates of crystallization of PEEK have been measuredin the temperature range of 260–325°C for melt-pressed films and solvent cast films. Detailed kinetic analysis indicated that PEEK exhibited an unmistakable regime II → III transition at 296 ± 1°C. The II → III transition was clearly present irrespective of the rather drastic changes in U*. It is interesting that the branching and crosslinking retarded the growth rate of PEEK, but a transition from regime II to regime III still existed. For melt-pressed films after equilibration at 400°C for 15 min, values of σ and q suggest that U* should be taken nearer to 1500 cal/mol in the case of T_∞ = T_g − 30 K and 2000 cal/mol in the case of T_∞ = T_g − 51.6 K. The K_g(III)/K_g(II) ratio (1.32) was not as close to the predicted value of 2 as was Hoffman's ratio. For PEEK, the Thomas-Staveley constant (β) should be closer to 0.25 or 0.3 instead of 0.1. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 1335–1348, 1998     

Photochemically Cross‐linked Poly(aryl ether ketone) Rings

Summary: Macrocyclic phenyl ether ketones were prepared via pseudo high dilution condensation. Irradiation of these rings with UV light in a solution containing isopropyl alcohol as hydrogen donor resulted in a photo‐induced reduction of benzophenone to benzopinacol and the formation linked macrocycles. These rings can be heated to undergo ring‐opening polymerization and produce a polymer network or they can be added to a polycondensation reaction to prepare poly(ether ether ketones) with variable degrees of cross‐linking.

Photochemical cross‐linking of PEK rings and ring opening polymerization (n: 2–6). (a) hν, iPrOH, DCM; (b) CsF, 260 °C (polymer 3 ); (c) 4,4′–difluorobenzophenone, hydroquinone, diphenylsulphone, K₂CO₃, 260 °C (2% polymer 4 ; 6% polymer 5 ).     

Absorption of toluene in poly(aryl-ether-ether-ketone)

The absorption and swelling of poly(aryl-ether-ether-ketone) (PEEK) in toluene as a function of resin morphology and temperature in the range 35–95°C was investigated. In all cases the weight gain curves exhibit three characteristics: (1) an induction period, which is a strong function of both temperature and initial crystallinity, (2) a main absorption region, which is linear with square-root time, and (3) a final equilibrium value, namely, solubility. The solubility of amorphous PEEK decreases with temperature and the heat of solution is ?0.93 kcal/mol. The induction period varies with the fourth power of the crystallinity and decreases with temperature with an apparent activation energy of 50 kcal/mol. The strength of the interaction between the crystalline regions is markedly reduced at temperatures greater than 80°C. Swelling accompanying the absorption of the toluene is highly anisotropic with most of the dimensional changes occurring in the thickness direction. The deswelling process, however, is essentially isotropic. The concentration of toluene in solution has a strong effect on the transport process; the equilibrium solubility of toluene in amorphous PEEK immersed in a toluene/iso-octane mixture is a linear function of toluene concentration; but the pseudo-diffusion coefficient for the absorption of toluene varies approximately with the fourth power of its concentration.