新型膨胀阻燃聚丙烯复合材料的协同效应

基于膨胀阻燃与协效阻燃相结合的技术制备了含协效剂的新型膨胀阻燃聚丙烯(PP)复合材料,其中的新型膨胀阻燃剂由硅凝胶包裹聚磷酸铵(OS-MCAPP)和三羟乙基异氰尿酸酯(THEIC)组成,协效剂为多孔磷酸镍(VSB-1)或磷酸镍纳米管(NiPO-NT)。结果表明,当VSB-1和NiPO-NT的添加量(质量分数)分别为4.0%和3.0%时复合材料的极限氧指数可达到最大值34.2,其最大热释放速率比不含协效剂时分别降低了40.7%和38.1%,表现出高效的阻燃协效性。同时,含有VSB-1和NiPO-NT阻燃PP复合材料的热稳定性显著提高,700℃时的残余质量比不含协效剂时分别提高了207%和239%。     

二维层状无机物/硼酸锌复合体系对聚苯乙烯泡沫阻燃性能的影响

通过三聚氰胺改性脲醛树脂包覆的方法来制备阻燃聚苯乙烯泡沫(EPS),阻燃体系以聚磷酸铵为基础,并选用3种二维层状无机物和硼酸锌的复配体系作为协效剂,对比了不同阻燃体系对聚苯乙烯泡沫的阻燃、抑烟和热稳定性的影响。实验结果表明:当膨胀石墨与硼酸锌的添加量为2∶1(质量比),两者总添加量为24phr时,复合材料的极限氧指数可达32.6%,UL-94垂直燃烧测试达V-0等级,烟密度等级降低至27.31;较之添加纯膨胀石墨EPS样品,协效剂硼酸锌的引入,使样品残炭强度由14.3增加到86.1。热失重分析结果表明,协效剂的加入使得样品热稳定性和残炭率均有所上升。从残炭宏观形貌和扫描电镜结果可以看出,硼酸锌的存在,使样品燃烧后残炭更加完整、致密,裂痕与破损明显减少。     

埃洛石纳米管协效阻燃改性沥青性能及机理研究

为研究埃洛石纳米管(HNTs)协效常规阻燃剂(CFR)改性沥青的阻燃性能及机理,首先采用极限氧指数仪、克利夫兰开口杯和锥形量热仪对SBS改性沥青、常规阻燃改性沥青和埃洛石纳米管协效阻燃改性沥青进行阻燃性能测试;然后采用热重?差示扫描量热仪(TGA?DSC)研究沥青燃烧过程的质量损失和热量变化,采用傅里叶红外光谱仪(FTIR)和热重?红外联用技术(TG?FTIR)研究沥青燃烧过程中固相物质和气态产物的时程变化,采用数码相机(DC)和场发射扫描电镜(FESEM)表征沥青残渣的宏微观形貌,来探寻HNTs协效CFR改性沥青的阻燃机制.研究结果表明:1％HNTs复配8％CFR(质量分数,下同)改性沥青的极限氧指数(LOI)和自燃温度(SIT)分别为25.5％、441℃,说明添加阻燃剂使沥青变为难燃物质;同时阻燃沥青的热释放速率峰值(PHRR)和烟释放速率峰值(PSPR)也明显降低,说明HNTs协效CFR改性沥青具有良好的阻燃性能和抑烟性能.通过热重及热量变化发现了阻燃剂靶向分解的吸热阻燃机理,通过固相物质的转变规律发现了磷酸催化沥青成炭的凝聚相阻燃机理,通过气态产物的转变规律发现了磷系自由基淬灭燃烧的气相阻燃机理,通过沥青残渣的形貌表征分析发现了阻燃剂增强残渣完整性和致密程度的阻隔层阻燃机理,最后基于全相态物质变迁规律揭示了HNTs协效CFR改性沥青的阻燃机制.     

PP/PVAc-OMMT纳米复合材料及其阻燃材料的燃烧性能

利用锥形量热仪(CONE)在35kW/m2热辐照条件下,并结合极限氧指数(LOI)和UL-94垂直燃烧测试方法对聚丙烯(PP)/聚醋酸乙烯酯(PVAc)-有机蒙脱土(OMMT)纳米复合材料和加入无卤复配阻燃剂制备的PP/PVAc-OMMT/氢氧化镁(MH)/三氧化二锑(AO)纳米复合阻燃材料的热释放速率、烟释放及材料在燃烧时的质量损失行为进行了研究。结果表明,添加10%(质量分数)PVAc-OMMT可以提高PP材料的阻燃性能,燃烧时的热释放速率、质量损失率以及烟释放量减少,且PVAc-OMMT与无卤复配阻燃剂之间可产生阻燃协效作用,使纳米复合阻燃材料的阻燃性能、热稳定性和抑烟性进一步增强。     

复合金属氧化物对膨胀阻燃聚丙烯的协效作用EI北大核心CSCD

研究了复合金属氧化物(LDHO)对膨胀阻燃聚丙烯体系(PP/IFR)的协效作用。以层状复合氢氧化物(LDH)为前驱物通过焙烧法制备了2种LDHO,分别为镁铝LDHO(MgAl-LDHO)、镁铝铁LDHO(MgAlFe-LDHO),并通过X射线衍射对LDH和LDHO进行了表征,采用熔融共混法制备了PP/IFR/LDHO复合材料,通过极限氧指数(LOI)、UL94垂直燃烧、锥形量热等方法考察了复合材料的阻燃性能。结果表明,2种LDHO均可以提高PP/IFR体系的氧指数,并使最高热释放速率(PHRR)大幅度降低,其中MgAl-LDHO可使PHRR降低71%;热重分析表明,LDHO的加入提高了PP/IFR体系的分解温度及残炭在高温区的热稳定性,从而提高了体系热稳定性能。采用扫描电镜观察了残炭的形貌结构,发现添加LDHO后炭层更加致密、坚实,表明通过改善PP/IFR炭层的质量,LDHO起到了协效阻燃的作用。     

阻燃剂THPPA的合成及与埃洛石复配在环氧树脂中的应用

通过2-羧乙基苯基次膦酸(CEPPA)与三羟甲基氧化膦(THPO)的酯化反应合成了含磷阻燃剂THPPA.用红外光谱、核磁共振确定了THPPA的结构和组成,并将埃洛石纳米管(HNTs)与THPPA复配用于环氧树脂阻燃改性.热重分析表明,HNTs与THPPA复配可以提高复合材料的热稳定性,降低分解速率并促进成炭.锥形量热测试显示,THPPA与HNTs复配使复合材料的热释放速率和总放热量分别降低了63.6％和56.8％,同时,复合材料的氧指数和垂直燃烧等级均有所提高.扫描电镜显示,HNTs与THPPA在凝聚相发挥协效作用,有助于环氧树脂燃烧后形成更致密的炭层.TGA-IR分析发现,分解产物中有P=O存在,表明有气相阻燃作用.力学性能测试表明,当THPPA和HNTs的添加量分别为8％和6％时,复合材料的拉伸强度和冲击强度与空白环氧树脂相比分别提高了4.0％和4.5％,冲击断面显示出韧性断裂的特征.     

复合金属氧化物对膨胀阻燃聚丙烯的协效作用

研究了复合金属氧化物(LDHO)对膨胀阻燃聚丙烯体系(PP/IFR)的协效作用。以层状复合氢氧化物(LDH)为前驱物通过焙烧法制备了2种LDHO,分别为镁铝LDHO(MgAl-LDHO)、镁铝铁LDHO(MgAlFe-LDHO),并通过X射线衍射对LDH和LDHO进行了表征,采用熔融共混法制备了PP/IFR/LDHO复合材料,通过极限氧指数(LOI)、UL94垂直燃烧、锥形量热等方法考察了复合材料的阻燃性能。结果表明,2种LDHO均可以提高PP/IFR体系的氧指数,并使最高热释放速率(PHRR)大幅度降低,其中MgAl-LDHO可使PHRR降低71%;热重分析表明,LDHO的加入提高了PP/IFR体系的分解温度及残炭在高温区的热稳定性,从而提高了体系热稳定性能。采用扫描电镜观察了残炭的形貌结构,发现添加LDHO后炭层更加致密、坚实,表明通过改善PP/IFR炭层的质量,LDHO起到了协效阻燃的作用。     

含硅阻燃大分子相容剂的制备及其在无卤阻燃聚乙烯复合材料中的协效作用

为验证含硅大分子相容剂在无卤阻燃体系中的协效阻燃作用,首先,以马来酸酐、硅橡胶与聚乙烯为原料,通过熔融接枝共聚制备了新型含硅阻燃大分子相容剂;然后,利用氢氧化铝、氢氧化镁和含硅大分子相容剂复配协同阻燃聚乙烯复合材料;最后,探讨了含硅大分子相容剂对复合材料极限氧指数、锥形量热参数、拉伸性能以及微观结构的影响。结果表明:与聚乙烯接枝马来酸酐相比,含硅大分子相容剂含量为10wt%时可使无机阻燃剂在基体树脂中分散较好;随着大分子相容剂含量的增加,复合材料的拉伸强度上升而断裂伸长率下降,极限氧指数提高至34.0%,燃烧时的热释放速率峰值和热释放总量均明显下降,说明含硅大分子相容剂除了能够在该复合材料中起到良好的相容作用外,还可以发挥较好的协效阻燃作用。     

阻燃抑烟环氧树脂的制备与性能

通过离子交换法将七钼酸根离子插入到含硝酸根的MgAl层状双氢氧化物(NO_3-MgAl LDHs)的层间,得到含钼酸根的MgAl层状双氢氧化物(Mo-MgAl LDHs),并将制得的LDHs加入到环氧树脂(ER)中制成复合材料ER/LDHs。通过热重分析、锥形量热、极限氧指数和烟密度等测试对复合材料的性能进行分析,结果表明,与纯ER相比,ER/LDHs复合材料的最大热释放速率(PHRR)、总的热释放量(THR)和烟密度都降低,氧指数提高,而且ER/Mo-MgAl LDHs复合材料的阻燃抑烟性能要比ER/NO_3-MgAl LDHs的更好;同时,添加少量LDHs可以提高复合材料的力学性能。     

聚合物/层状硅酸盐纳米复合材料的阻燃性能研究进展

从热稳定性能、燃烧和发烟行为、成炭行为、氧指数和UL94阻燃级别等方面,对聚合物/层状硅酸盐纳米复合材料(PLSN)阻燃性能的研究进展进行了综述,分析和探讨了PLSN的阻燃机理,展望了其发展趋势和应用前景。     

Insertion of triangulated surfaces into a meccano tetrahedral discretization by means of mesh refinement and optimization procedures

In this paper, we present a new method for inserting several triangulated surfaces into an existing tetrahedral mesh generated by the meccano method. The result is a conformal mesh where each inserted surface is approximated by a set of faces of the final tetrahedral mesh. First, the tetrahedral mesh is refined around the inserted surfaces to capture their geometric features. Second, each immersed surface is approximated by a set of faces from the tetrahedral mesh. Third, following a novel approach, the nodes of the approximated surfaces are mapped to the corresponding immersed surface. Fourth, we untangle and smooth the mesh by optimizing a regularized shape distortion measure for tetrahedral elements in which we move all the nodes of the mesh, restricting the movement of the edge and surface nodes along the corresponding entity they belong to. The refining process allows approximating the immersed surface for any initial meccano tetrahedral mesh. Moreover, the proposed projection method avoids computational expensive geometric projections. Finally, the applied simultaneous untangling and smoothing process delivers a high‐quality mesh and ensures that the immersed surfaces are interpolated. Several examples are presented to assess the properties of the proposed method.     

From Industry 4.0 to Research 4.0. Development of High Performance Fibers in the Light of Digitization

We associate a variety of innovations with the term ＂Industry 4.0＂. The pioneer of many 4.0 modifications forms the basisfor the trend towards the integrated di...     

Roman iron and steel: A review

ABSTRACT

The production of ferrous metal increased during the Roman Late Republican period, Principate and Empire. The direct bloomery process was used to extract the metal from its ores using slag-tapping and slag-pit furnaces. The fuel was charcoal and an air blast was introduced by bellows-operated tuyères. Iron formed as a bloom, often as a spongy mass of metal, which contained impurities from the smelting process, including unreacted ore, fuel, slag and fragments from the furnace walls, while the metal was often inhomogeneous with varied carbon contents. Blooms were either smithed directly into bars or ingots or they were broken up, which also allowed the removal of gross impurities and a selection of pieces with similar properties to be made. These could then be forge-welded together and formed into characteristically shaped ingots. Making steel in the furnace seems to have been achieved: it depended on the ore and the furnace and conditions within it. Surface carburization was also carried out. Iron and steel were used extensively in construction and for tools and weapons. Fire welding was often used to add pieces of steel to make the edges of tools and weapons, which could be heat-treated by quenching to harden them.     

The Research of Anti-Wear Properties of Organomolybdenum Compounds in the Engine Oils

A four-ball tester was used to evaluate the anti-wear performance of three kinds of organomolybdemun compounds in the engine oils, i. e., molybdenum dialkyldithiophosphate (MoDDP), molybdenum dialkyldithiocarbamate ( MoDTC), and sulphur and phosphorus freeorganomolybdeum (Molybdate). The results indicate that a low concentration of MoDDP doesn' t improve the anti-wear properties of the commercial engine oils, but a high concentration of MoDDP can obviously improve the anti-wear properties and the load-carrying capacity of the engine oils. MoDTC doesn' t improve the antiwear properties of the engine oils, but worsens the anti-wear properties of the oils. Signifi can timprove ment of frictional and wear characteristics is obtained with Molybdate added in the commercial engine oils and the formulated oils.     

Certification Institutions Expected to Update and Transfer Information on Present Standards

Standards are the basis for production enterprises to organize production, ex-factory inspection, trade (delivery) and technical exchanges, product certification, quality arbitration and supervision.……     

Flow calorimeter for enthalpy increment measurements on condensed gases

A flow calorimeter for enthalpy increment measurements on condensed gases is presented. A better knowledge of the properties of the liquefied natural gas is needed, and therefore a liquid loop has been designed for our flow calorimeter. The fluid loop in the calorimeter is designed in order to avoid the two-phase region, since two phases would give compositional disturbances in the measurements. The avoidance of the two-phase region is made possible by increasing the pressure of the test fluid after the measurement section, then heating the fluid at super-critical pressure past the critical point. Finally, the fluid is throttled to the low-pressure gas state at the inlet condition of the compressor that circulates the fluid. To perform the pressure increase, a new cryogenic pump has been designed. To evaluate the new equipment, measurements were taken on liquid ethane over the temperature range 146–256 K at pressure between 0.9 and 5.1 MPa.     

Synthesis of Alumina-Zirconia Nanocomposites by Solgel Process

Al₂O₃-ZrO₂ nanocomposites were developed starting with the solgel process. Composite alumina-zirconia nanopowders were synthesized from metallorganic precursors (Aluminium secondary butoxide and zirconium Iso propoxide) using the solgel process. The parameters affecting the synthesis—solvent, concentration of precursor, R/H ratio (i.e., dilution of water in solvent)—were varied as also the temperature and pH. BET and TEM were used to measure nanosize. Diffuse reflectance spectroscopy and also qualitative optical absorption led to identical particle size estimate. The variation of process parameters was used to study the effect and interdependence of process parameters. Artificial Neural Networks was used to rigorously analyze the process. Although this led to confirmation of interdependence of parameters, the presence of a single overwhelming solvent variable was also established. Then the optimal process was used to synthesize more nanopowder. To produce bulk nanocomposite the nanopowders were sintered by varying the temperature and time period. The sintered lithoids were probed with a vickers hardness tester to measure elastic modulus, hardness, and fracture toughness. The results showed high elastic modulus, modest hardness, and very high fracture toughness.     

Refrigerators Enter a New Era of Health Preservation Frestech initiates the establishment of China's first standard for household sterilization refrigerators

On November 30, 2007, the China Association for Standardization (CAS) held a press conference at Beijing Diaoyutai State Guest House. Leaders from the China Household Electric Appliance Research Institute, the China Household Electric Appliance Association, and the China Consumers' Association attended and made speeches.……     

Friction Stir Processing Strategies for Uniform Distribution of Reinforcement in a Surface Composite

Friction stir processing (FSP) is an important technique for preparing surface composites. Fabricating defect-free surface composites with uniform particle distribution by FSP is a challenging task. In this study, silicon carbide particles reinforced AA5083 alloy surface composites was fabricated using different FSP strategies including variation in process parameters, dual-tool processing and tool offset overlapping. Material flow of the processed material with reinforcement particles demonstrated that the distribution of particles was influenced by the stirring action of the probe as well as the extrusion of the plasticized material due to the movement of the tool. Process parameters, particularly rotational speed, showed a dominant influence on the distribution of silicon carbide particles.