无皂乳液法制备聚甲基丙烯酸甲酯/改性凹凸棒土复合微球及其性能研究

凹凸棒土(AT)经提纯后,使用y-甲基丙烯酰氧基丙基三甲氧基硅烷(KH-570)对其进行有机改性,得到有机化的凹凸棒土(OAT),并对其进行FT-IR、TG表征.结果表明,KH-570对凹凸棒土起到了良好的修饰改性作用.采用无皂乳液法制备了聚甲基丙烯酸甲酯(PMMA)/改性凹凸棒土(OAT)核壳复合微球.借助扫描电镜、...     

Matting films prepared from waterborne acrylic/micro‐SiO2 blends

Acrylic resin/micro‐SiO₂/polymethyl urea (AC/SiO₂/PMU) composites were prepared by physical blends of acrylic resin latex (AC), polymethyl urea resin (PMU), and modified SiO₂. The effects of SiO₂ and PMU content in the hybrid composites morphology and physical properties were investigated in detail using transmission electron microscopy (TEM), UV‐Vis spectrometry (UV‐Vis), scanning electron microscope (SEM), thermogravimetric analysis (TGA), and contact angle measurement. The results showed that introduction of SiO₂ into AC composites could increase the viscosity which caused by gelation and agglomeration of SiO₂. The TEM, SEM images, and TGA results indicated that hybrid membranes have phase separation. During the film formation process, a high number of PMU and SiO₂ particles of an appropriate size were stranded on the surface of the film to form matting surface. These results highlight the sensitivity of the gloss to the polymer morphology and surface. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41707.     

异型桥的模型试验研究

由于Y型薄壁箱梁的力学特性,初等梁基本理论不能很好地解决其复杂的力学特性。为了解决这个问题,选择来自不同Y型桥的Y型薄壁箱梁作为研究对象,根据相似理论制作聚甲基丙烯酸甲酯模型作为试验模型,其比例为1/30。测试通过对模型产生不同的变形及不同的测试点,施加三种剪力及六种荷载工况。测试结果表明,受约束的扭曲、变形和Y型薄壁箱梁的剪滞效应问题显著。与初等梁的模型相比,该模型能正确反映Y型薄壁箱梁的力学行为。在此基础上,提出了Y型薄壁箱梁的计算理论和分析方法。     

溶液浇铸聚甲基丙烯酸甲酯薄膜的DSC研究

用ＤＳＣ观测了溶液浇涛ＰＭＭＡ薄膜的热焓松弛行为,对物理老化,溶液浓度以及溶剂极性对其热焓松弛行为的影响进行了详细的讨论,其特征用凝聚缠结的观点予以解释。     

热力历史对PMMA残余应力和光学性能的影响

利用光弹测量对注射成型过程不同热力历史的聚甲基丙烯酸甲酯(PMMA)样件进行了残余应力的定量表征,并测试分析了样件的透光率和雾度。研究表明,成型过程中的工艺选择对样件的残余应力影响显著,提高熔体温度和模具温度、增大保压压力和注射速度、缩短保压时间和冷却时间都可以有效降低残余应力;退火温度升高可明显削弱成型过程热力历史的差异,降低残余应力并使之趋于一致,偏差最小为0.71 MPa。热力历史对光学性能的影响与残余应力相关性较大,总体上残余应力降低,透光率升高而雾度降低,可分别达到93.1%和1.1%。     

Ga‐doped zinc oxide: An attractive potential substitute for ITO,large‐area coating,and control of electrical and optical properties on glass and polymer substrates

Abstract— Ga‐doped ZnO (GZO) films with thicknesses of 30–560 nm were prepared on glass substrates at 200°C by ion plating with direct‐current arc discharge. The dependences of the characteristics of GZO films on thickness were investigated. All the polycrystalline GZO films, which showed high transmittance in the visible region, were ZnO crystallites with a wurtzite structure highly oriented along the (0002) plane. The resistivity, ρ, of GZO films decreases with increasing film thickness. The highest ρ achieved is 4.4 × 10⁻⁴ Ω‐cm with a carrier concentration, n, of 7.6 × 10²⁰ cm⁻³ and a Hall mobility, μ, of 18.5 cm²/V‐sec, determined by Hall effect measurement for the GZO films with a thickness of 30 nm, and the lowest ρ is 1.8 × 10⁻⁴ Ω‐cm with n = 1.1 × 10²¹ cm⁻³ and μ = 31.7 m²/V‐sec for the GZO film with a thickness of 560 nm. In addition, highly transparent GZO films with thicknesses of 12–300 nm were fabricated on unheated polymethyl methacrylate (PMMA). The ρ of these transparent GZO films decreased from 20 to 4 × 10⁻⁴ Ω‐cm with film thickness.     

Conduction mechanism in doped polymethyl methacrylate (PMMA) films

The electrical transport behaviour of ferrocene mixed poly (methyl methacrylate) (PMMA) films (≈ 20 μm in thickness) deposited by the isothermal immersion technique has been studied in the temperature range of 333–373 K and field from (2·0–4·0)×10⁴ V/cm. It has been found that at higher fields and temperatures, the observed conduction behaviour could be consistently described by the Richardson-Schottky emission. The increase in current due to doping has been attributed to the formation of charge transfer complexes. The dopant molecules act as an additional trapping centre and provide a link between polymer molecules in amorphous region leading to the formation of charge transfer complex.     

Peridynamic assessment of mechanical and thermal characteristics of a defected PMMA/HA composite beam

Polymer-based composites are designed to improve mechanical and thermal characteristics. This study utilized a peridynamic methodology to simulate polymethyl methacrylate/hydroxyapatite composite beams. The simulation involved the crack growth within the computational domain, and an analysis was conducted to evaluate the mechanical and thermal properties of the defected system. The outcomes derived from the peridynamic analysis revealed that an augmentation in the hydroxyapatite ratio within the samples resulted in a decrease in their mechanical and thermal efficiencies. To elucidate further, at an impact velocity of 2 mm/s, the flexural modulus increased to 3.69 GPa, the flexural strength decreased to 132.34 MPa, and the thermal conductivity converged to 0.148 W/m·K, when the hydroxyapatite ratio was at 15%. In the course of the conducted investigations, it became evident that the impact velocity significantly influences the evolutionary behavior of particles within the samples. In particular, with an increase in the impact velocity up to 5 mm/s, the thermal conductivity decreased to 0.139 W/m·K. The results of this study indicate that by modifying the hydroxyapatite ratio and impact velocity, it is possible to control the mechanical and thermal properties of the polymethyl methacrylate/hydroxyapatite composite beams. This optimization allows for their suitability in various engineering applications.     

移动X射线光刻制备等腰三角形结构的PMMA微通道

利用移动X射线光刻工艺,制备了六种不同深宽比的等腰三角形结构的聚甲基丙烯酸甲酯(PMMA)微通道。基于毛细管原理,将PMMA微通道与老鼠血液接触,对血液进行了微量采集。该PMMA微通道是中间带有凹槽结构的等腰三角形结构,凹槽结构的宽度为10μm、长度为6.7~39.4μm。将32个高度为35 mm的PMMA微通道的基板垂直插入老鼠血液样品中,通过实验测定了六种不同等腰三角形结构的PMMA微通道的接触角、表面张力及血液上升高度。结果表明,在一定范围内,PMMA微通道的深宽比越大,血液上升越容易,液体提取量也越多。对于通道横截面长度为39.4μm的微通道,样品血液在15 s时的上升高度可达到20.45 mm,达到最终30 s时上升高度的89.9%以上。     

造孔剂和发泡剂结合法制备氟化羟基磷灰石多孔支架研究

本研究采用添加造孔剂和发泡剂相结合法制备多孔氟化羟基磷灰石, 合成具有大孔与小孔套连、3D方向上分布的多孔支架。通过化学沉淀法制备了氟化羟基磷灰石(FHA)粉体, 以碳酸氢铵为发泡剂、PMMA为造孔剂, 通过烘干和烧结工艺制备孔洞均匀且相互贯通、坯体致密的多孔支架。经X射线衍射分析, 支架的相组成是FHA和β-TCP。SEM观察结果显示支架孔洞形貌规整、大孔尺寸100~400 µm, 小孔尺寸10~50 µm。以HA和β-TCP为原料对造孔方法的普适性进行验证, 并对支架孔的形成及其影响因素进行了分析。