排水性沥青混合料路用性能改善措施

为提高排水性沥青混合料的路用性能,从级配、胶结料类型和添加剂的角度分析排水性沥青混合料路用性能的影响因素,并推荐了改善其路用性能的相关措施.研究结果表明:随着空隙率的增加,排水性沥青混合料稳定性变差,表面功能特性增强;60℃动力黏度是排水性沥青混合料胶结料最关键的指标;纤维添加剂可以明显提高排水性沥青混合料的耐久性;消石灰可以改善排水性沥青混合料的水稳定性.排水性沥青混合料材料组成应该以高黏沥青为胶结料,掺加聚酯纤维;水稳定性要求高的地区可以采用消石灰同比例替代矿粉.     

非离子纤维素醚改性水泥浆的孔结构

通过表现密度测试及宏观、微观孔结构观察,研究不同分子结构非离子纤维素醚对水泥浆孔结构的影响.结果表明,非离子纤维素醚会导致水泥浆孔隙率增加;非离子纤维素醚改性水泥浆黏度相近时,羟乙基纤维素醚(HEC)改性水泥浆的孔隙率比羟丙基甲基纤维素醚(HPMC)和甲基纤维素醚(MC)改性水泥浆小;基团含量相似的HPMC纤维素醚,黏度/相对分子质量越低,其改性水泥浆孔隙率越小.非离子纤维素醚掺入水泥浆后,降低了液相表面张力,使得水泥浆容易形成气泡;非离子纤维素醚分子定向吸附在气泡气-液界面,同时还增加了水泥浆液相黏度,使得水泥浆稳定气泡的能力增强.     

Equivalent linear limit states

The replacement of any limit state function by an equivalent linear function is discussed in detail and it is shown that there are several methods by which such an equivalence may be established. In the case of multiple failure mode problems the definition of fully equivalent linear functions requires the additional consideration of mode correlations. The manner in which this may be carried out is discussed and it is shown that, for most practical cases, a relatively simple analysis is likely to be sufficient to define the set of equivalent linear limit states, with the advantage that the established theory of such linear limit states may then be employed in the majority of reliability analyses.     

C80高强混凝土的研发与试应用

该文介绍了C80预拌混凝土的研发与试应用过程,包括原材料选择、配合比设计、配合比验证,以及混凝土搅拌、运输、泵送、振捣和养护。为重庆预拌混凝土企业提供参考。     

Synthesis of phenyl silicone resin with epoxy and acrylate group and its adhesion enhancement for addition-cure silicone encapsulant with high refractive index

A novel phenyl silicone resin with epoxy and acrylate group (PSREA) was successfully synthesized via the non-hydrolytic sol-gel condensation reaction of 3-glycidoxypropyltrimethoxysilane, 3-methacryloyloxypropylmethyldimethoxysilane, and diphenylsilanediol, and was employed as the adhesion promoter for addition-cure silicone encapsulant (ASE) with high refractive index. The structure of PSREA was confirmed by Fourier transform infrared spectroscopy, ¹H nuclear magnetic resonance spectroscopy, and ²⁹Si nuclear magnetic resonance spectroscopy. The influence of PSREA on the properties of ASE was studied. It was found that PSREA could markedly enhance the adhesion strength of ASE to aluminum (Al) and poly(p-phenylene terephthamide) (PPA) substrate. When the content of PSREA was 1.5 phr, the shear strength of ASE was 4.43 and 2.27 MPa for Al and PPA substrate, which was about 71 and 266% higher than that of ASE without the adhesion promoter, respectively. In addition, PSREA had little effect on the mechanical properties, refractive index, and viscosity of ASE.     

间位芳纶溶解及凝固性能研究

以二甲基乙酰胺(DMAc)、二甲基甲酰胺(DMF)、二甲基亚砜(DMSO)、1-甲基-2-吡咯烷酮(NMP)为溶剂,分别加入LiCl和CaCl_2制备溶解体系,研究了间位芳纶在这几种溶解体系中的溶解性能。再以H_2O-DMAc、H_2O-DMF、H_2O-DMSO、H_2O-NMP为凝固浴,研究了溶剂种类、芳纶溶液质量分数、离子浓度等对间位芳纶溶液的凝固性能的影响。结果显示:Li Cl-DMAc溶解体系具有更强的溶解性能;凝固值随凝固浴中凝固剂H_2O的含量的增加不断减小,而临界浓度几乎没有变化;随着凝固浴温度的增加,凝固值增大,临界浓度减小;凝固值随凝固浴中离子浓度的升高而增大,但临界质量分数则不断降低。另外,间位芳纶溶液的扩散系数随着凝固浴中H_2O的含量的减少不断减小,随着芳纶浓度的增加不断减小。     

稠油催化改质降粘的实验研究

制备了4种油溶性过渡金属石油酸盐催化剂,进行了室内稠油催化改质降黏实验,评选出了最优催化剂及其最佳反应条件。结果表明,在石油酸铁质量分数为0.12%、改质温度365℃、改质时间40 min的条件下,可使鲁克沁稠油黏度从17 460降至125 mPa·s,降黏率达99.28%。改质稠油饱和分增加了17.61%,胶质减少了18.55%,350、500℃以下馏分分别增加了9.82%、29.45%。改质油轻组分的增加便于稠油降黏和管输,降低了能耗。     

Stepwise cure and properties of silicone resin for high‐ultraviolet‐transmission optical elements

A new high‐ultraviolet (UV)‐transmission silicone‐resin polymeric material was prepared via curing during hydrosilylation of tetramethyltetravinylcyclotetrasiloxane with tetramethylcyclotetrasiloxane by a liquid‐surface supernatant method, using a stepwise heating program to avoid spontaneous combustion of the reaction mixture. The relationships were investigated in detail between reactive groups, cross‐linking density, mechanical and UV‐transmission properties. For this purpose, UV transmittance and dynamic mechanical properties, respectively, of the silicone resin were measured with UV–visible spectrophotometry and dynamic mechanical thermal analysis. In addition, surface roughness was evaluated with an atomic force microscope as well as an interferometer. The curing process was monitored by Fourier transform infrared spectroscopy and rotational rheometry. The cyclic silicone oils were compared with linear ones in structure and product properties. The results indicated that stepwise temperature control during curing process was particularly indispensible due to the presence of active Si? H bonds, and that the silicone resin of high modulus, high UV transmittance (92.7%) and low surface‐roughness was largely homogeneous in cross‐linking points distribution. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43308.     

Curing behavior and processability of BMI/3‐APN system for advanced glass fiber composite laminates

The prepolymers containing bismaleimide (BMI) and 3‐aminophenoxyphthalonitrile (3‐APN) were prepared through simple solution prepolymerization, and the corresponding curing behaviors and processability were investigated by differential scanning calorimetry and dynamic rheological analysis. The results showed that the processability of the prepolymers could be controlled by temperature and time on processing, also depended on the relative content of 3‐APN and BMI. The possible curing reactions of the prepolymers were studied by Fourier transform infrared spectroscopy, which involved the Michael addition between BMI and 3‐APN and self‐polymerization of BMI or 3‐APN. The resulting polymers displayed high thermo‐oxidative stabilities (T_5% > 425 °C) and good adhesion capability. Furthermore, BMI/3‐APN systems were employed to prepare BMI/3‐APN/glass fiber (GF) composite laminates and their morphological, mechanical, and electrical stable properties were also investigated. The BMI/3‐APN/GF laminates exhibited the improvement of the mechanical properties (the maximum flexural strength is 633.5 MPa and flexural modulus is 38.7 GPa) compared with pristine BMI/GF laminates because of the strong interfacial adhesions between GF and matrices, which was confirmed with SEM observations. This study provides a concise strategy for diversifying the preparation of BMI/3‐APN prepolymers to obtain advanced GF composite laminates with various properties which have potential applications in industrial manufacture or electronic circuit, and so on. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43640.