单裂隙类花岗岩材料单轴抗压强度与破裂特征试验研究

为了探究单轴压缩条件下裂隙岩石的强度特性、起裂应力和破坏模式,对预制单裂隙试样进行单轴压缩试验,结果表明:与完整试样相比,裂隙试样单轴抗压强度随裂隙倾角的增加而降低,α=90°时,强度最低;当裂隙倾角小于45°时,试件破裂以反翼型裂纹为主;倾角大于75°时,以翼型裂纹为主。裂隙尖端应力随裂隙倾角发生改变,裂隙倾角为0～60°时,裂隙尖端产生拉应力集中区,在张拉作用下产生反翼裂纹;当裂隙倾角为75～90°时,裂隙尖端产生剪应力集中区,剪应力作用产生翼型裂纹。裂隙岩石试件的单轴压缩力学特性及破裂模式揭示了单裂隙岩石的力学行为特征,为破碎岩体支护及控制技术研究提供了科学依据。     

新型沥青路面灌缝胶的研制

针对沥青路面灌缝材料存在的粘结性不高、低温脆裂、高温流淌等问题,通过抗剪强度试验、接触角试验、拉拔试验分别研究了水性环氧树脂和改性乳化沥青的最佳配比、抗剪强度、粘结强度。结果表明：水性环氧树脂能够增加改性乳化沥青的抗剪强度,且水性环氧树脂与改性乳化沥青最佳配比为2:3;灌缝胶的接触角大于90°。研究制备的灌缝胶具有良好的粘结性和抗老化性,适用于沥青路面裂缝处治。     

立式循环撞击流反应器中桨叶垂直交错排布条件下的混合性能

立式循环撞击流反应器(VCISR)桨叶的倾角及其布置形式,是影响混合性能的重要因素.本文采用数值方法对VCISR桨叶不同角度垂直交错排布条件下的混合性能进行了研究.上下两对桨叶倾角θ均设置为45°,上下两对桨叶错位角分别设置为15°、30°、45°、60°,结果表明:上下两对桨叶错位角在45°时,VCISR特征撞击面上...     

磷酸改性高环氧值环氧树脂

在磷钨酸催化下,用磷酸改性高环氧值环氧树脂得到了水性化树脂。探究了环氧树脂与磷酸的物质的量比、磷钨酸加入量(相对于环氧树脂的质量)、温度、时间、丙酮加入量和搅拌速率对环氧基转化率的影响,采用正交试验法优化工艺条件,以傅里叶变换红外光谱(FT-IR)和核磁共振(NMR)表征产物,并测试其性能,建立了不同温度下的反应动力学模型。结果表明：在搅拌速率100 r/min的情况下,5个因素对转化率的影响次序为：温度>丙酮加入量>环氧树脂与磷酸的物质的量比>磷钨酸加入量>反应时间。较优的工艺条件为：环氧树脂与磷酸的物质的量比1∶2,磷钨酸量加入量1.3%,温度45°C,时间130 min,丙酮15 mL。环氧基转化率可达98.07%。该反应在35、45和55°C下均为二级反应,活化能约为26.6 kJ/mol。     

环氧树脂改性聚脲涂层的制备及性能

用二苯基甲烷二异氰酸酯(MDI50)与聚醚多元醇(1000D)合成异氰酸酯基封端聚醚醇预聚体(A组分),再与含有1000D、端氨基聚醚(D2000)、自制改性环氧树脂和4,4?-双仲丁氨基二苯基甲烷(6200)的R组分混合反应,制备成环氧树脂改性聚脲。与不含环氧树脂的聚脲涂层相比,环氧树脂改性聚脲涂层的性能均得到一定程度的改善。当用自制环氧树脂完全取代R组分中的1000D和D2000后,所制涂层的综合性能最好,拉伸强度由4.55 MPa提升至16.63 MPa,耐45%(质量分数,后同)H_2SO_4溶液、75%H_3PO_4溶液和45%NaOH溶液的表现良好;其初始分解温度由288.1°C升至334.1°C,失重50%时的温度由368.0°C升至403.5°C;玻璃化温度由12.6°C升至90.0°C,阻尼温度域变宽,tanδ峰值变大。     

复合型环氧树脂胶粘剂对混凝土裂缝的修复性能

分别以丁腈橡胶、糠醛/丙酮和聚氨酯接枝改性的NH2-nano-Si02来增韧环氧树脂,以研制性能更好的复合型环氧树脂胶粘剂.根据不同的胶粘剂,对不同修复材料试样的基本力学性能、抗压强度等特性进行考察以及评价.通过最终的试验数据分析,获取较佳的混凝土裂缝修复方式.     

改性环氧树脂固体颗粒冲蚀磨损试验研究

采用气流挟沙喷射法对改性环氧树脂材料进行固体颗粒冲蚀磨损试验,考查冲蚀速度和角度对其冲蚀磨损的影响,并探讨了其冲蚀磨损机理,对比了相同冲蚀条件下几种材料冲蚀率的大小。实验结果表明,改性环氧树脂材料冲蚀率与冲蚀速度近似呈线性关系;在不同的冲蚀速度下,改性环氧树脂材料的冲蚀率在45°冲蚀时最大,表现出半塑性材料的冲蚀特征;在相同的冲蚀条件下,改性环氧树脂材料冲蚀率是对比材料(如M30砂浆、水泥石等)冲蚀率的1/16~1/4,适合用作强风沙流环境下混凝土桥梁墩身的防护材料;冲蚀形貌扫描电子显微镜照片表明,冲蚀能量的法向分量使材料表面产生裂纹和破碎,而其切向分量使材料表面产生切削。     

粉煤灰堆场改性黄土衬里的渗透试验研究

通过一系列渗透试验,研究了不同添加剂改性黄土的防渗性能。选用黏性较大的兰州黄土和砂性较大的榆林黄土两种代表性黄土为防渗衬里主料,分别向其中添加不同比例的膨润土、石灰、水泥和粉煤灰作为改性材料,进行渗透试验。结果表明,膨润土细颗粒充填于黄土颗粒大孔隙中,水化膨胀后减小了孔隙体积并且阻隔了孔隙间的贯通性,能有效降低改性衬里的渗透系数。石灰、水泥和粉煤灰在降低改性衬垫渗透系数方面作用不大,由于水化反应形成新的复合土颗粒骨架和网格骨架,反而会使渗透系数增大,不适合作为黄土改性衬里的改性材料。     

有机硅含量对改性酚醛环氧树脂涂料性能的影响

利用自制的有机硅改性酚醛环氧树脂配制耐热防腐涂料，对其性能进行试验。不同有机硅树脂百分含量影响改性酚醛环氧树脂清漆的综合性能，并确定了有机硅的含量在40-60％时改性涂料具有较好的综合性能；探讨了不同温度下涂膜附着力的变化及在不同酸碱溶液中不同有机硅含量的改性涂料的耐蚀性。     

有关室内消火栓水枪上倾角的探讨

相关规范书刊推荐室内消火栓水枪上倾角为45°,最大60°。对于低层高建筑物,按此角度计算不能充分利用消火栓充实水柱长度。提出根据工程实际确定水枪上倾角,用于后续消火栓保护半径计算。     

玻纤铺层方向对玻纤/EVE复合材料性能的影响

以0°,90°,0°/90°,0°/45°/-45°/90°分别作为玻璃纤维(GF)单向铺层方式,研究了不同的铺层方式对GF/EVE(环氧乙烯基酯树脂)复合材料力学性能的影响。结果表明,0°铺层方向的复合材料在单一方向的力学性能最好,0°/45°/-45°/90°铺层方向的复合材料可以看作各向同性材料,应用范围更加广泛。     

端羟基液体丁腈橡胶改性环氧树脂的结构与性能

用端羟基液体丁腈橡胶(HTLN)与2,4-甲苯二异氰酸酯进行反应得到HTLN预聚体,用其对环氧树脂进行化学改性,得到HTLN改性环氧树脂;考察了HTLN用量对改性环氧树脂微观形貌、拉伸强度和剪切强度的影响及改性环氧树脂的抗磨蚀性能。结果表明,随着HTLN预聚体用量的增加,改性环氧树脂的拉伸强度、剪切强度先升高后降低,在其质量分数为30%时,拉伸强度和剪切强度达到最高;在施加的负荷和HTLN用量一定的情况下,改性环氧树脂的磨蚀随滑动速率的增加而明显增加。     

Rice‐husk‐ash‐based silica as a filler for embedding composites in electronic devices

We carried out a feasibility study of the use of black rice husk ash (RHA) as a filler in epoxy resin for embedding material in electrical and electronic applications. We made a comparison by mixing RHA and two commercial fillers, fused and crystalline silica, with epoxy resin at weight fractions ranging from 20–60%. RHA‐filled epoxy resin had higher mixing viscosity, coefficient of thermal expansion, and water absorption percentage than commercial‐silica‐filled epoxy composite. However, the impact strength of all composites was comparable, but the tensile strength and elongation at break of silica‐filled epoxy were slightly superior. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 3013–3020, 2002     

含巯基聚硅氧烷改性环氧树脂的制备及性能

以双酚A环氧树脂（E51）为基料、聚醚胺（D?230）为固化剂、含巯基聚硅氧烷（PMMS）为改性剂,分别经过简单物理混合和化学改性的方法,制备了一系列聚硅氧烷改性环氧树脂（E51⁃D⁃PMMS）固化物。通过衰减全反射红外（ATR?FTIR）和X射线衍射仪（XRD）表征了固化物的结构特征;通过拉伸测试和冲击实验、扫描电子显微镜（SEM）、接触角测量（CA）、动态热力学分析（DMA）及中性盐雾实验探究了改性固化物的力学性能、热稳定性、防腐性能等。结果表明,化学改性的E51?D?PMMS固化物的综合物理化学性能优于简单物理改性的,当PMMS含量为1 %（质量分数,下同）时,改性固化物的拉伸强度为74.63 MPa,较改性前提高了13.5 %,断裂伸长率提高了40.2 %,冲击强度提高了43.7 %;水接触角从改性前的72.8 °增至100.3 °,表面能从39.4 J/m²降至17.4 J/m²,吸水率下降了44 %,耐水性能大大增强;其防腐性能和玻璃化转变温度（T_g）也有一定的提升。     

表面改性处理对氧化铝/环氧树脂复合材料力学性能的影响

对未改性和表面偶联处理的氧化铝颗粒填充环氧树脂复合材料(颗粒体积分数为20%,35%和40%)的力学性能进行对比研究.通过对改性前后复合材料结构的均匀性和抗拉伸性能的分析得出以下结论:添加了偶联处理后的氧化铝颗粒使复合材料的均匀性、断裂强度和弹性模量都有了较大程度的提高.原因在于对颗粒的表面偶联改性处理使颗粒间存在的黏聚吸附力下降,增加了颗粒与树脂基体间的结合力,使氧化铝颗粒能够在树脂基体中达到很好的分散状态.采用扫描电镜分析手段对样晶断口形貌的分析说明材料内部界面问的结合状态以及颗粒在基体中的分布状况.     

纳米SiO_2改性环氧树脂胶粘剂的研究

选择纳米 SiO_2 作为增强材料改性环氧树脂基体, 以物理分散法将纳米 SiO_2 分散在环氧树脂中。通过力学性能测试和热稳定性能测试, 研究了不同含量的纳米 SiO_2 对改性环氧树脂胶粘剂的热性能、拉伸性能和冲击性能的影响; 通过 NOL环测试和扫描电子显微镜(SEM) 分析, 研究了不同含量的纳米 SiO_2 对国产芳纶纤维/改性环氧复合材料的界面性能和层间剪切强度的影响。实验结果表明, 基体树脂中当 w( 纳米SiO_2)=3%时, 改性环氧树脂胶粘剂的拉伸强度和冲击强度分别提高了 28.8%和 22.6%, 复合材料的层间剪切强度(ILSS) 达到最大值, 比未改性胶粘剂提高约 56.8%。     

Mechanical properties of an epoxy resin toughened by polyester

The epoxy resins were toughened by 4–24 phr polyester with average molecular weight 1.9×10⁴ g/mol in this investigation. The mechanical properties were examined and dynamic mechanics analyses were performed for the epoxy resins before and after the modification. The toughening mechanism of polyester to epoxy resin is discussed in light of the scanning electronic microscopy observation of the fracture surfaces. The results showed that the impact strength and tensile strength of the modified epoxy resin were remarkably greater than those of the unmodified cured epoxy resin. The most suitable composition for the modified epoxy resin was the addition of 16 phr polyester, which led to 138 and 46% increments in the impact strength and the tensile strength, respectively. And the mechanical properties depended greatly on the congregating state of polyester added. The polyester dispersing in the epoxy matrix was amorphous when its addition was less than or equal to 12 phr, and was sphere crystals when the addition was over 16 phr. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 3384–3389, 2003     

风电叶片用EP胶粘剂的研究

以不同增韧剂改性EP(环氧树脂)为基体树脂,采用曼尼希改性胺为固化剂制备了不同改性EP胶粘剂。研究结果表明:当增韧剂为聚氨酯(PU)预聚体时,相应的改性EP胶粘剂的粘接性能优异;在上述体系中加入玻璃纤维增强填料后,相应的改性EP胶粘剂的综合力学性能和粘接性能俱佳,其拉伸强度超过75.00 MPa、拉伸模量超过4.00 GPa、断裂伸长率超过4.00%且90°剥离强度超过10.00 kN/m,属于高韧性EP胶粘剂,并且完全满足风电叶片的使用要求。     

Laboratory investigation of the properties of asphalt modified with epoxy resin

Epoxy asphalts were prepared by mixing styrene–butadiene–styrene (SBS) modified asphalt with epoxy resin. The curing process and morphology of epoxy asphalts were characterized by infrared spectroscopy and fluorescent microscope, respectively. The effects of epoxy resin contents, ratio of curing agent to epoxy resin and curing temperature on properties of epoxy asphalt were investigated. Results indicated that epoxy resin and epoxy asphalt showed similar curing efficiency. Epoxy asphalts can be cured at 120 or 60°C and its viscosity at 120°C can meet the demands of asphalt mixture mixing and paving. The chemical reaction of epoxy resin in epoxy asphalt is slow and reaction occurs not only with the curing agent but also carboxylic acid in epoxy asphalt. The microstructure of epoxy asphalt transforms from the dispersed structure to networks structure with epoxy resin content increasing and phase transition starts when 30 wt % epoxy resin present in asphalt. The softening point and tensile strength of epoxy asphalt increased with epoxy resin contents increasing. The softening point and tensile strength of epoxy asphalt were markedly improved when epoxy resin content was more than 30 wt %, which is attributed to formation of continuous structure of epoxy resin. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Dispersion,Mechanical and Thermal Properties of Epoxy Resin Composites Filled with the Nanometer Carbon Black

The nanometer carbon black (CB) was employed to prepare epoxy resin/carbon black (EP/CB) composites by blending-casting method. The different modified methods of silicone coupling agent were used to improve the dispersion of CB in epoxy resin. The mechanical and thermal properties of EP/CB composites were investigated. Experimental results showed that the mechanical properties increased at first, but decreased with excessive addition of CB. When the mass fraction of CB was 2%, the mechanical properties were maximum. The use of modified CB significantly enhanced the mechanical properties of the composites. For given CB loading, the CB modified by pretreatment method displayed better dispersion in the epoxy resin than that of the direct mixing method. SEM observation revealed that the tensile fracture surface of the composite filled with 2 wt% modified CB held more microcracks than that of 5 wt% modified CB, and the formed microcracks could consume more energy of rupture, finally to have better tensile strength. DSC analysis showed that the glass transition temperature (Tg) of the composites increased with the increasing mass fraction of CB.