半互补集合的相依切锥和极限法锥的刻画

根据零模函数的变分性质,带有零模约束的优化问题、零模正则问题和零模极小化问题都可以转化为带有半互补约束集合的约束优化问题。而刻画约束优化问题的约束集合的相依切锥和极限法锥,对获得该优化问题的最优性条件起着至关重要的作用。本文主要刻画了半互补集合的相依切锥、正则法锥和极限法锥,丰富了非连续、非凸规划问题的最优性理论,为进一步研究带有零模约束的优化问题、零模正则问题和零模极小化问题奠定了理论基础。     

规整填料在铜洗塔中的应用

叙述了铜洗塔中铜氨液吸收合成气中少量CO，CO2的反应机理和传质机理，介绍了规整填料的结构特点以及所需配套进行的铜洗塔内件改造和铜液过滤器改造。实际应用表明：使用规整填料改造铜洗塔可优化工艺操作。提高设备技术。投资回报快，节能降耗效果显著。     

Modelling the post treatment process of model implants prepared by in situ polymerized poly(ε-caprolactone) using a BF3-glycerol catalyst system

The post treatment process of a poly(ε-caprolactone) (PCL) model implant prepared using a boron trifluoride (BF₃) catalyst and glycerol initiator by in situ polymerisation process for craniofacial and maxillofacial treatment is modelled using a ‘moving-boundary’ diffusion model. A numerical method was used to solve a system of diffusion equations of the model. The variable diffusion coefficient (D) was correlated with crystallinity (x_c) of the polymer which is a function of its molecular weight (M_w) and its degradation rate constant (k_d), D=f(x_c(M_w,k_d)). The post treatment time and the molecular weight retained after post treatment can be obtained using this model. The modelling results show that the process is potentially suitable for manufacturing thin model implants of complex shape.     

Crystallization and thermoelectric behavior of conductive-filler-filled poly(ε-caprolactone)/poly(vinyl butyral)/montmorillonite nanocomposites

Crystallization and thermoelectric properties of poly(ε-caprolactone) (PCL)/poly(vinyl butyral) (PVB)/montmorillonite (MMT) nanocomposites containing carbon black (CB) have been studied as a functions of a small amount of amorphous PVB content and a wide range of molecular weight of PVB. X-ray diffraction data of PCL/PVB/MMT nanocomposites indicates most of the swellable silicate layers are exfoliated and randomly dispersed into PCL/PVB system. The band spacings of PCL spherulites in PCL/PVB/MMT nanocomposites decrease with increasing PVB content, and this indicates that increasing the PVB content greatly shortens the period of lamellar twisting. The presence of 1 wt% MMT and higher molecular weight of PVB also shorten the period of PCL lamellar twisting. Nucleation and crystallization parameters, such as growth rate G and Avrami exponent n, can be determined by using POM and DSC isothermally crystallized at 41 °C. For samples with the same CB content, the intensity of positive temperature coefficient (PTC) (I_PTC, defined as the ratio of peak resistivity to resistivity at room temperature) of the nanocomposites was increased as the content and the molecular weight of PVB increases. The change of the PTC property related to the morphological difference (i.e. period of lamellar twisting) in the nanocomposites can be discussed.     

Crystal structure, melting behaviour and equilibrium melting point of star polyesters with crystallisable poly(ε-caprolactone) arms

Star polymers consisting of poly(ε-caprolactone), PCL, attached to third generation dendrimer, hyperbranched and dendron cores have been studied by differential scanning calorimetry and wide-angle X-ray scattering. The degree of polymerisation of the PCL arms of the star polymers ranged from 14 to 81. The crystal unit cell was the same for the star polymers as for their linear PCL analogues. The star polymers showed a lower degree of crystallinity than the linear PCL, suggesting that the dendritic cores imposed restriction on PCL crystallisation. Slow heating of rapidly cooled samples led to crystal rearrangement—a gradual increase in melting point with decreasing heating rate and recrystallisation followed by additional high temperature melting. The tendency for crystal rearrangement was less pronounced in star polymers based on dendrimer or hyperbranched cores, suggesting that the dendritic cores constitute an obstacle to crystal rearrangement. The star polymers showed higher equilibrium melting points than the linear PCL analogues. It is suggested that covalent attachment of the PCL arms to the dendritic core reduced the positional freedom and the entropy of the melt with respect to that of linear PCL.     

"变压吸附"疲劳容器使用应注意的问题

介绍了“变压吸附”使用的疲劳容器以及使用过程中应注意的检查事项。     

Synthesis and characterization of two polytrimellitamideimide series with different segment order by direct polycondensation

Poly(amide–imide) (PAI) could be synthesized in regular segment order from trimellitic anhydride (TMA) and various aromatic diamines. By different processes, PAI_{h‐h‐t‐t} containing alternating (amide–amide)–(imide–imide) sequences and PAI_h‐t containing amide–imide sequences could be obtained through direct polycondensation. Comparison of PAI_{h‐h‐t‐t} and PAI_h‐t, which had different sequence orders and were prepared from TMA and 12 diamines, showed that the latter had better solubility and needed less quantity of solvent and salt (CaCl₂) during polymerization, but both two series PAI using p‐substituted diamines (e.g., p‐phenylenediamine) showed poor solubility. Series PAI_{h‐h‐t‐t} possessed larger initial modulus but smaller elongation at break than series PAI_h‐t. For the thermal properties, most of series PAI_h‐t had glass transition temperatures higher than corresponding series PAI_{h‐h‐t‐t}, but these two series were similar in the 10% weight loss temperatures and the char yields at 800°C in nitrogen. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 1556–1567, 2001     

Poly(ε-caprolactone) Diols (HOPCLOH) and Their Poly(ester-urethanes) (PEUs): The Effect of Linear Aliphatic Diols [HO–(CH2)m–OH] as Initiators

α,ω-Hydroxy telechelic poly(ε-caprolactones) were prepared by ring-opening polymerization of the ε-caprolactone catalyzed by ammonium decamolybdate in the presence of different aliphatic diols [HO–(CH₂)_m–OH, where m?=?2, 4, 6, 8, 10, 12, 14, and 16] as initiators to obtain a family of α,ω-hydroxy telechelic poly(ε-caprolactone) [HO–PCL–O–(CH₂)_m–O–PCL–OH, m?=?2, 4, 6, 8, 10, 12, 14, and 16]. The content of the alkyl group (AG) (–(CH₂)_m–) had an important effect on the crystallinity (x_i) of α,ω-hydroxy telechelic poly(ε-caprolactone), showing a proportional relationship. In poly(ester-urethanes) derived from α,ω-hydroxy telechelic poly(ε-caprolactones) and 1,6-hexamethylene diisocyanate, the AG also showed a similar effect on the x_i and eventually on the mechanical properties, increasing the values of the modulus. Therefore, AG content was a factor to induce a plastic behavior in poly(ester-urethanes). The effect of AG on the water uptake of poly(ester-urethanes) after 1 week was negligible.     

纳米氧化锌在NR/BR并用胶及SBR胶料中的应用

研究纳米氧化锌替代普通氧化锌在天然橡胶(NR)/顺丁橡胶(BR)并用胶以及丁苯橡胶(SBR)胶料中的应用。结果表明,纳米氧化锌减量10%代替普通氧化锌,NR/BR并用胶及SBR胶料的加工性能和物理性能基本不变,质量减小,成本降低。     

聚酯晶体等温增厚行为的研究

以分子量较小、分子量分布较窄的聚己内酯(PCL)为研究对象,探讨了聚酯类高分子晶体等温增厚的行为。研究结果表明:随着等温结晶温度的升高,增厚速率依次增大。等温增厚过程可分为两个阶段,在第一阶段中,长周期与等温时间满足一定的线性关系;在第二阶段中,长周期逐渐偏离直线。