脱醇型模具硅橡胶的性能评价体系初探

探讨了模具硅橡胶的性能评价体系，指出仅通过黏度、密度、拉伸强度、撕裂强度、断裂伸长率、硬度等常规指标来评价模具硅橡胶的性能是不全面的。一个比较完整的模具硅橡胶性能评价体系应该由以下几个部分组成：物理性能、机械性能、结构化倾向、操作性能、模具的尺寸稳定性及耐老化性等，并介绍了这几种性能的袁征方法。     

A simple and fast fabrication of a both self-cleanable and deep-UV antireflective quartz nanostructured surface

Both self-cleanability and antireflectivity were achieved on quartz surfaces by forming heptadecafluoro-1,1,2,2-tetrahydrodecyltrichlorosilane self-assembled monolayer after fabrication of nanostructures with a mask-free method. By exposing polymethylmethacrylate spin-coated quartz plates to O₂ reactive ion etching (RIE) and CF₄ RIE successively, three well-defined types of nanopillar arrays were generated: A2, A8, and A11 patterns with average pillar widths of 33 ± 4 nm, 55 ± 5 nm, and 73 ± 14 nm, respectively, were formed. All the fabrication processes including the final cleaning can be finished within 4 h. All nanostructured quartz surfaces exhibited contact angles higher than 155° with minimal water droplet adhesiveness and enhanced transparency (due to antireflectivity) over a broad spectral range from 350 to 900 nm. Furthermore, A2 pattern showed an enhanced antireflective effect that extends to the deep-UV range near 190 nm, which is a drawback region in conventional thin-film-coating approaches as a result of thermal damage. Because, by changing the conditions of successive RIE, the geometrical configurations of nanostructure arrays can be easily modified to meet specific needs, the newly developed fabrication method is expected to be applied in various optic and opto-electrical areas.PACS codes: 06.60.Ei; 81.65.Cf; 81.40.Vw.     

移动式修补硫化机控制系统的设计

首先介绍了可移动修补硫化机的工作原理及对控制系统的要求。论述控制系统硬件配置和选型过程。并对硫化三要素的控制进行详细说明。设备使用后效果良好。     

A robust,portable H-TDMA for field use

The complexity of a typical hygroscopicity tandem differential mobility analyser (H-TDMA) can make it an awkward instrument for fieldwork. An improved design is presented here which is both light-weight, portable and permits very precise, reliable hygroscopic growth, deliquescence and efflorescence measurements for aerosols over a continuous relative humidity range from 10% to 95% without reconfiguration.The method achieves this through three significant advances in H-TDMA design: Firstly, the approach efficiently regulates the humidity by rapidly alternating the air flow between a dryer and a saturator, with the time spent in each path controlled by a feedback loop connected to the humidity sensor. Secondly, the temperature of the aerosol humidifier is directly coupled to that of the wet DMA by enveloping the humidifier in the wet DMAs excess air flow. Thirdly, a novel arrangement of two Nafion? tubes in the humidifier allows for high humidities without needing to pre-wet the aerosol flow.     

A sub-0.5 μm bilevel lithographic process using the deep-UV electron-beam resist p(si-cms)

Optimization of the deep-UV and electron-beam lithographic properties of a copolymer of trimethylsilylmethyl methacrylate (SI) and chloromethylstyrene (CMS), P(SI-CMS), within a weight average molecular weight range of 1.4 to 4.1 × 10⁵ and 90 to 93 mole percent SI composition has been achieved. The solubility behavior of P(SI-CMS) resist was examined using the Hansen 3-dimensional solubility parameter model and dissolution rate measurements. Swelling of the resist has been minimized through the identification of a single component developer (2-propanol) and rinse (water) system. For the material containing 90 mole percent SI (14.9 weight percent Si) and M?_ω = 1.4 × 10⁵, the sensitivity to 248 nm radiation is 65 mJ/cm² and to electron-beam exposure is 3.4 μC/cm² at 20 kV. This material Is applicable to bilevel lithographic processes, and the O₂ reactive ion etching (RIE) rate is 16 times slower than standard hard-baked photoresist. Using a He/O₂(60/40) RIE pattern transfer process, 0.4 μm line/space patterns have been resolved in a 1.3 μm bilayer structure for deep-UV exposures, and 0.25 μm imaging has been demonstrated in a 0.7 μm thick planarizing layer using electron beam irradiation. The loss in linewidth associated with the 0.25 μm process is ～0.04 μm.     

A robust shock and noise model for the manufacturing of molded LDPE foams

The article concerns the injection manufacturing process of molded foam sheets and their intrinsic shock and noise performances. The main goal is to optimize the physical performances of molded plastic foams at an early stage in their design and manufacturing. The effects of injection process parameters on the properties of molded LDPE foams are investigated. The input optimization parameters considered are: injection temperature, mold temperature, injection speed, plasticization back pressure, and screw rotation speed during the plasticization phase. The output optimization parameters considered are: density, shock absorption, and acoustic absorption. The experimental design method made use of the Taguchi table and central composition design. This allows us to identify simplified mathematical models for input/output and to detect the most influential input in the injection process. We conclude by validating the models and their robustness. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers     

A novel method for improving the surface quality of microcellular injection molded parts

Microcellular injection molding is the manufacturing method used for producing foamed plastic parts. Microcellular injection molding has many advantages including material, energy, and cost savings as well as enhanced dimensional stability. In spite of these advantages, this technique has been limited by its propensity to create parts with surface defects such as a rough surface or gas flow marks. Methods for improving the surface quality of microcellular plastic parts have been investigated by several researchers. This paper describes a novel method for achieving swirl-free foamed plastic parts using the microcellular injection molding process. By controlling the cell nucleation rate of the polymer/gas solution through material formulation and gas concentration, microcellular injection molded parts free of surface defects were achieved. This paper presents the theoretical background of this approach as well as the experimental results in terms of surface roughness and profile, microstructures, mechanical properties, and dimensional stability.     

Poly(methyl methacrylate) as masking material for microelectromechanical system (MEMS) fabrication

In the present study direct current (dc) sputtered poly(methyl methacrylate) (PMMA) films deposited on silicon substrates were evaluated as masking materials for anisotropic etching of silicon in aqueous potassium hydroxide (KOH) and tetramethyl ammonium hydroxide (TMAH) solutions. Sputtered PMMA films were characterized by FTIR to ascertain the bonding, by X‐ray photoelectron spectroscopy (XPS) for the elemental composition, and by the contact angle for measuring the adhesion of the film with the substrate. FTIR and XPS data showed the presence of a poly(tetrafluoroethylene)‐like film on the silicon substrate. The interfacial tension was calculated from the contact angle value, which was 0.82 dyne/cm, confirming good adhesion of the film and the substrate. A pattern was lithographically transferred through the masking material on the silicon substrate, and the etch rate of the masking layer was calculated from the masking time data of the films. The etch rate value of 4 Å/min obtained for the masking material is low compared to the etch rate of the conventional masking materials (60 Å/min for SiO₂ and 8 Å/min for Si₃N₄). © 2006 Wiley Periodicals Inc. J Appl Polym Sci 102: 2094–2098, 2006     

A basic study of orientation in poly(ethylene terephthalate) stretch-blow molded bottles

A series of stretch-blow molded poly(ethylene terephthalate) bottles were investigated using measurements of birefringences (in plane and out of plane) and wide angle x-ray diffraction (WAXS) pole figures. Both bottles prepared in our laboratories and commercial bottles were investigated. Birefringences Δn₁₃ and Δn₂₃ of inside and outside surfaces of bottles were determined as a function of position along the length of the bottle (1-bottle axis, 2-hoop direction, 3-thickness direction). The Δn₁₃, Δn23 for the inside surface of the bottles were found to be greater than those for the outside surface indicating heterogeneity through the thickness of the bottles. The WAXS studies indicate that the benzene rings in the polymer align parallel to the bottle surface. The chain axis in crystalline regions exhibit orientations close to equal biaxial orientation. Both Δn₁₃ and Δn₂₃ increased with inflation pressure.     

A unified K-BKZ model for residual stress analysis of injection molded three-dimensional thin shapes

The flow-induced and thermally induced residual stresses during injection molding of a thin part with complex geometries are predicted. The injection molding precess was considered to consist of a filling and a post-filling stage (packing coupled with cooling). Additionally, the analysis were applied to successive stages of the process. The model takes into account the viscoelasticity of the molding polymer, which has been neglected in most previous works, because of the complexity of its inclusion. A unified K-BKZ viscoelastic constitutive model, capable of modeling both the fluid-rubbery state and the glass state of amorphous polymers, was employed for simulating this problem. For the flow-induced residual stress predictions of the filling stage, a quasi-steady state approximation was employed for each element of the part, for the calculation of stress profile and subsequent stress relaxation after cessation of flowf. Stress calculations were provided for the thermally induced residual stress predictions of the post-filling stage. These explicit calculations led to the results of pressure and temperature distributions of the part during the post-filling stage into the viscoelastic constitutive model. Additionally, the pressure and asymmetric temeprature profiles of the post-filling stage were based on finite element packing analysis coupled with a boundary element cooling analysis of the molding process. Finally, the total residual stress in the part was obtained via superposition of the flow-induced and thermally induced residual stresses. An example is provided to demonstrate the entire concept. The results indicate that thermally induced residual stress is higher than the flow-induced residual stress by one to two orders of magnitude.     

Evaluation of portable dilution system for aerosol measurement from stationary and mobile combustion sources

This study presents the emission factor of PM_2.5, elemental carbon (EC), organic carbon (OC), and water-soluble ions for biomass-fired-induced downdraft gasifier and light duty diesel vehicle (LDDV). A portable dilution system (PDS) developed for on-field measurement of aerosol and their precursors from combustion sources were used for quenching of aerosol at near-atmospheric condition before collection on filters. PDS consists of a heated duct and particle sampling probe, dilution tunnel, zero air assembly, and a power supply unit. PDS was evaluated under controlled conditions in laboratory for gasifier cookstove and LDDV over wide range of dilution ratios to understand the effect of dilution on mixing, particle formation, and loss. The invariability in CO₂, recorded along the length and at radial distances of cross-section of dilution tunnel, confirmed the rapid and homogenous mixing inside the dilution tunnel. The particle loss and nucleation inside the dilution tunnel accounted for 6–20% at different dilution ratios (30:1–90:1). PM_2.5 emission factors for wood combustion in gasifier cookstove showed mild decrease (13%) with increasing dilution ratio from 75:1 to 108:1. However, a considerable decrease of 37% (221–139 mg km^?1) was observed for LDDV with increase in dilution ratio from 39:1 to 144:1. Similar decrease in particulate organic carbon emission rates were observed indicating scarcity of sorptive organics, and insufficient residence time for condensation limited the particle formation from vapor phase organic compounds at high dilution ratios.

© 2016 American Association for Aerosol Research     

基于DSP的便携式多功能电能测量仪的应用研究

介绍了DSP技术在电力测量中的应用，经A/D采样后的电流，电压送入DSP芯片，并进行相关处理。得到所需的电流和电压的平均值。有功功率及功率因数等电力参数。本系统还可以通过通信模块进行远程测量和数据传输。该方法具有灵活，可升级和高效的特点。     

A surface model‐based simulation for warpage of injection‐molded parts

The mid‐plane model for warpage simulation of injection‐molded parts requires a mid‐plane mesh whose transformation is considerably time consuming. To overcome this drawback, a surface model‐based warpage simulation is presented, in which the part is represented as a perfect bonding of two half‐thickness plates with their reference surfaces at the outer boundary of the part. The plates over the surface mesh are modeled as flat shell elements, and a new triangular flat shell element is developed which combines an Assumed Natural DEviatoric Strain (ANDES) based membrane component and a Refined Nonconforming Element Method (RNEM) based bending component. The bonding is accomplished by multipoint constraints and a Lagrange multiplier based elimination method is proposed for constraint application. The results show that compared with some popular shell elements, ANSYS, Moldflow and the experiments, the presented model exhibits a high performance in computation accuracy. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers     

Evaluating the performance of a portable water–mist fire extinguishing system with additives

This study investigates how high‐pressure water–mist system discharge methodologies influence the fire extinction performance for pan pool fires and the corresponding mechanisms of restraining fire. The fire source is a pool‐fire burner. Fine water spray is injected using a portable device. The additive in the water–mist is neither toxic nor corrosive. All the tests are regarded as fuel controlled. The fire test parameters are fuel type, nozzle discharge angle, and additive solution volume. The fuels used are heptane, gasoline, and diesel. Nozzle discharge angles are 30, 45, and 60° with respect to the ground. Additive solution volumes are 0% (pure water), 3, 6, and 10%. Test results indicate that the nozzle discharge angle and additive solution volume in a water–mist fire extinction system play a significant role. Fire extinguishing efficiency is influenced by mist effects and the additive. Furthermore, the water–mist system can reduce radiation and can provide good protection for operators using portable fire extinguishing equipment. Copyright © 2008 John Wiley & Sons, Ltd.     

A comparative study for the behavior of 3D-printed and compression molded PLA/POSS nanocomposites

Because of the biocompatible and nontoxic character of both PLA (polylactide) and POSS (Polyhedral Oligomeric Silsesquioxane) nanoparticles, recently being a significant alternative for biomedical parts; the main purpose of this study was to investigate performance of the 3D-printed PLA/POSS nanocomposites with respect to the compression molded PLA/POSS specimens. Due to the higher uniformity and higher homogeneity in the distribution of POSS nanoparticles in each PLA matrix layer, mechanical tests (tensile, flexural, and toughness) revealed that the improvements in the strength, elastic modulus and fracture toughness values of the 3D-printed specimens were much higher compared to their compression molded counterparts, the benefits starting from 13% increasing up to 78%. It was also observed that there was almost no deterioration in the physical structure and mechanical properties of the 3D-printed specimens, even after keeping them 120 days at 37°C in a physiological solution prepared by using the standard PBS (phosphate buffered saline) tablet.     

A method for studying damage in a fiber reinforced thermoplastic by masking viscoelastic effects

A technique and some preliminary results of a study of the damage state of a long fiber reinforced thermoplastic composite are presented, emphasizing the difficulty encountered when the matrix material contributes significant viscoelastic effects to the material response. The type and origin of these effects are reviewed, as is the theory that has been developed allowing for removal of the superimposed viscoelastic effects. It is demonstrated that the complicating effect of the superimposed viscoelasticity can be successfully removed, thereby providing a less confusing presentation of the data and offering the potential for greatly simplified design and analysis.     

A gene clustering method with masking cross-matching fragments using modified suffix tree clustering method

Multiple sequence alignment is a method for comparing two or more DNA or protein sequences. Most multiple sequence alignment methods rely on pairwise alignment and Smith-Waterman algorithm [Needleman and Wunsch, 1970; Smith and Waterman, 1981] to generate an alignment hierarchy. Therefore, as the number of sequences increases, the runtime increases exponentially. To resolve this problem, this paper presents a multiple sequence alignment method using a parallel processing suffix tree algorithm to search for common subsequences at one time without pairwise alignment. The cross-matched subsequences among the searched common subsequences may be generated and those cause inexact-matching. So the procedure of masking cross-matching pairs was suggested in this study. The proposed method, improved STC (Suffix Tree Clustering), is summarized as follows: (1) construction of suffix tree; (2) search and overlap of common subsequences; (3) grouping of subsequence pairs; (4) masking of cross-matching airs; and (5) clustering of gene sequences. The new method was successfully evaluated with 23 genes inMus musculus and 22 genes in three species, clustering nine and eight clusters, respectively. This paper was prepared at the 2004 Korea/Japan/Taiwan Chemical Engineering Conference held at Busan, Korea between November 3 and 4, 2004.     

Model-based analysis of the feasibility envelope for autonomous operation of a portable direct methanol fuel-cell system

Portable power systems based on direct methanol fuel cells (DMFC) have to provide power in various environmental conditions: it is advantageous for such a power-supply system to be autonomous, i.e. able to operate without water refills for the methanol solution. It is shown that system autonomy depends mainly on environmental humidity, condenser temperature and air excess ratio: this result is valid in general for any DMFC, as cell parameters have only a marginal role. The environmental conditions in which a portable DMFC system may be autonomous are considered, delineating a feasibility envelope. Two methods are proposed to extend this envelope: operating with a diluted methanol reservoir, which improves the autonomy of the system only marginally and at the cost of a large loss in energy density, and system pressurisation, which delivers a more significant improvement in autonomy properties, but at the cost of system efficiency and simplicity.