Study on hydrophilicity of polymer surfaces improved by plasma treatment

Surface properties of polycarbonate (PC), polypropylene (PP), polyethylene terephthalate (PET) samples treated by microwave-induced argon plasma have been studied with contact angle measurement, X-ray photoelectron spectroscopy (XPS) and scanned electron microscopy (SEM). It is found that plasma treatment modified the surfaces both in composition and roughness. Modification of composition makes polymer surfaces tend to be highly hydrophilic, which mainly depended on the increase of ratio of oxygen-containing group as same as other papers reported. And this experiment further revealed that CO bond is the key factor to the improvement of the hydrophilicity of polymer surfaces. Our SEM observation on PET shown that the roughness of the surface has also been improved in micron scale and it has influence on the surface hydrophilicity.     

Textbook representations of radian angle measure: The need to build on the quantitative view of angle

Empirical studies of angle, angle measure, and radian angle measure have primarily focused on documenting students' and teachers' conceptions. Representations of angle measure have the potential to inform and build on these conceptions. To gain insight into the concept of radian angle measure from a curricular perspective, I investigated the representations of radian angle measure in eight widely used U.S. high school mathematics textbooks. The data for this study are the 20 figures and the 8 definitions of radian angle measure in the textbooks. Inductive content analysis was used to identify the frequency of observable characteristics in the representations. Textbook figures of radian angle measure most frequently focus on a one-radian angle. Textbook figures also demonstrated radian angle measures in terms of π, in standard position, even when the Cartesian-coordinate plane was not in the figure. The frequently used characteristics of radian representations could inadvertently reinforce a qualitative concept of angle, instead of fostering the quantitative attributes of radian angle measure. Moving forward, analyzing conceptions that are evoked by the frequently used representations of radian angle measure could build a link between evidence from this study and studies of learning.     

A New Green Thermoplastic Polymer with Improved Hydrophobic Character

Summary: A green thermoplastic polymer based on wheat flour was modified by the addition of a natural crosslinker genipin. Films of the polymer modified with different composition of genipin were prepared by extrusion. Free surface energy using contact angle method, moisture absorption test and hardness test were used to characterize the products. From moisture absorption and contact angle measurements, it was seen that for genipin amounts higher than 0.2% w/w, a hydrophobic character is achieved. Results obtained indicate enhancement in hydrophobic properties of the films.     

Surface structure and properties of poly-(ethylene terephthalate) hydrolyzed by alkali and cutinase

This study was aimed at comparatively investigating the hydrolysis of crystalline and amorphous poly-(ethylene terephthalate) films by alkali and cutinase. Changes of surface properties were investigated by FTIR spectroscopy (ATR mode). The A₁₃₄₁/A₁₄₁₀ and I₁₁₂₀/I₁₁₀₀ absorbance ratios, and the full width at half maximum of the carbonyl stretching band (FWHM₁₇₁₅) were used to evaluate the polymer crystallinity and its changes upon hydrolysis. The effect of different treatments on chain orientation was evaluated by calculating R ratios of appropriate bands. The spectroscopic indexes showed that both alkali and enzyme treatments induced structural and conformational rearrangements with a consequent increase in crystallinity in both amorphous and crystalline films. The crystalline PET film was modified more strongly by alkali than by cutinase, while the opposite occurred for the amorphous one. The trend of the water contact angle (WCA) clearly indicates that alkali is more effective than cutinase in enhancing hydrophilicity of PET films and that the effect is stronger on amorphous than on crystalline films. The values of WCA correlate well with the FTIR indexes calculated from the spectra of hydrolyzed crystalline PET films. The mechanism of the surface hydrolysis of PET by alkali and cutinase is discussed.     

Effect of L64 on the Phase Behavior of 1-Dodecyl-3-methylimidazolium Chloride/Water System

Phase behavior of ternary system involving surfactant‐like ionic liquid 1‐dodecyl‐3‐methylimidazolium chloride ([C₁₂mim]Cl), water, and nonionic surfactant PEO‐PPO‐PEO block copolymer (Pluronic L64) is investigated at 25°C. Hexagonal (H₁) and lamellar liquid crystal phase (Lα) are found in [C₁₂mim]Cl/H₂O/L64 system by using polarized optical microscopy (POM), small‐angle X‐ray scattering (SAXS) techniques and ²H NMR spectra. The phase structure (H₁ phase), which is formed in [C₁₂mim]Cl/H₂O binary system, is not changed when L64 with a low concentration is added. However, phase transitions will occur from hexagonal to multiphases of H₁ and cubic phases (C), then to Lα+C phases with constant [C₁₂mim]Cl/H₂O ratio and increasing L64 concentration. Moreover, at given L64 (5%, 20%) concentration, the lattice parameter of H₁ or Lα phase decreases with increasing [C₁₂mim]Cl/H₂O ratio. Fourier transform infrared (FTIR) spectra indicate that the H‐bonded network comprising an imidazolium ring, chloride ion and water formed in [C₁₂mim]Cl/H₂O binary system is disrupted upon addition of L64. This is helpful to the phase transition, due to the decreasing of interfacial curvature induced by dehydration of hydrated layer after the addition of PEO block of L64.     

Design Criterion for Micro-Machine Scanner Optical Switch Based on Beam Steering Angle Error Analysis

The micro-machine scanner optical switch is gaining attention for its ability to switch over 100 ports. A beam steering error for devices using tilted mirrors or a moving lens is analyzed and schemes to overcome the limit are reported. The channel number is limited by the achievable beam steering error. A device with several hundred ports is possible with the beam steering error under 1#x0025;. Optimized focal length or fiber mode divergence angle is beneficial for increasing the channel number. To minimize the thermal expansion effect, large focal length is required indicating need for a compensation scheme to attain larger channel number. A new type of scanning optics is proposed to overcome the limit set by the beam steering error, and a new switch network described can further expand the channel number.This paper was originally presented at the 2nd International Conference on Optical Design and Fabrication, ODF2000 which was held on November 15-17, 2000 at the International Conference Center, Tokyo, Waseda University, Japan.     

利用光栅测量任意入射角方式下的光波波长

以光栅衍射方程为理论依据，讨论了在任意入射角方式下，如何利用光栅和分光计对光波波长进行测量并同时能得到未知入射角的值。给出了理论推导和实验结果。结果表明：该方法的所得到的光波波长的相对误差为0．21％。     

Effects of Ar/H/N‐ion bombardment on the surface free energy and friction behavior of the fullerene‐like hydrogenated carbon (FL‐C:H) film

The surface modification of the fullerene‐like hydrogenated carbon (FL‐C:H) film was achieved by bombardment using Ar, H, and N ions, respectively. A systematic comparison of X‐ray photoelectron spectroscopy (XPS) and Fourier transformation infrared(FTIR) spectra was made between the FL‐C:H film and ion‐bombarded films. The results show that ion bombardment resulted in the increase of sp³ C content, specially, new C? N bonds were formed for N‐ion‐bombarded film. The contact angle (CA) and friction coefficient of those films were measured. The surface free energy evaluated from the contact angle increased for ion‐bombarded films, and the most obvious increase was obtained for N‐ion‐bombarded film. The friction coefficient decreased for H‐ion‐bombarded film whereas it increased for N‐ion‐bombarded film, and the friction coefficient of Ar‐ion‐bombarded film was close to that of the FL‐C:H film. Copyright © 2008 John Wiley & Sons, Ltd.     

随机单调算子的满射性及应用

研究Banach空间中的随机单调算子,建立了连续随机单调算子的随机锐角原理、随机满射定理、随机双射定理及Hilbert空间上的一类连续随机算子的新的随机不动点定理,并应用随机强单调算子理论讨论了随机Hammerstein积分方程随机解的存在唯一性.     

Cavitation and morphological changes in polypropylene deformed at elevated temperatures

Polypropylene (PP) thick films were subjected to tensile drawing at various temperatures from the room temperature to 100 °C. Morphological alterations during drawing were followed by wide‐angle X‐ray scattering, small‐angle X‐ray scattering, and scanning electron microscopy (SEM) of sectioned and etched samples, volume strain measurement, and light transparency measurement at various level of strain. The morphological observations were paralleled with stress–strain determination. Samples drawn at 25 and 40 °C undergo severe cavitation contributing to their volume increase up to 90–95%. The volume increase contributes greatly to the engineering strain. PP drawn at 70 and 100 °C does not cavitate. At the strain up to 1.2, a high lamellae orientation is observed in SEM, whereas the 2D WAXS patterns show in contrary circular diffraction rings indicating low orientation of crystals. The rotation of lamellae toward drawing direction is associated with reverse rotation of chains in crystals due to fine chain slips. These two rotations in opposite directions counterbalance resulting in a much weaker crystal orientation than expected from the SEM images. Noncavitating samples retain their translucency up to a high strain. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 1271–1280, 2010