在线光电离质谱结合GC/MS研究阻燃型聚氨酯的热解

本工作利用热重（TG）、气相色谱-质谱（GC/MS）以及在线光电离质谱法对聚氨酯硬泡（RPUF）和添加了阻燃剂聚磷酸铵（APP）与可膨胀石墨（EG）的RPUF的热解过程进行了研究。热重分析结果显示,3种材料的热降解过程均可分为两个阶段。GC/MS对3种材料热解产物的检测结果表明,APP的加入促使大量含氮多环芳烃生成,这些多环芳烃加速了高温下RPUF表面焦炭层的形成,有助于提高阻燃效果;而EG对于RPUF热解产物没有明显影响,说明EG是一种典型的物理膨胀型阻燃剂。在线光电离质谱的实验结果进一步验证了上述结论,并得出RPUF、RPUF/APP、RPUF/EG热解过程的两个阶段分别来自聚氨酯的初始热分解以及初始热解产物的二次分解。     

STA-FT-IR-GC/MS联用技术在烟草热解过程研究中的应用

将同步热分析、傅立叶红外光谱和气相色谱-质谱组成联用检测系统,对样品在氮气和氮氧混合气氛中的热解产物经傅立叶红外光谱,并对不同温度点的主要热解产物GC-MS进行同步分析。该方法能够对样品进行在线分析和热解产物的分析研究,联用技术减少样品前处理过程中的浓缩和转移,减少了分析结果的人为因素,使分析结果的准确性、精密度大大提高。     

改性HTPE和HTPB的多谱学表征和热裂解机理研究

为研究端羟基聚丁二烯(HTPB)和端羟基聚醚(HTPE)黏合剂端基和主链改性对其热解特性的影响，本工作利用U型固定床热解反应器结合光电离质谱(SPI-MS)在线检测装置开展改性后黏合剂的热解实验。首先，采用红外光谱(FTIR)仪、核磁共振氢谱(¹H-NMR)仪和热重分析(TGA)仪表征和分析改性后黏合剂的结构和热解性能，再通过在线质谱实时动态分析改性黏合剂热解产物的组分变化，研究改性黏合剂的热解反应机理。结果表明，HTPB和HTPE的端基和主链改性后的黏合剂表现出不同的热稳定性，其中，主链改性对HTPB热解行为的影响大于端基改性，这2种改性方法都使热解过程中反应类型增多，进而导致产物种类增加。     

在线热解-光电离质谱法研究Li2CO3对松木热解的影响

利用热重分析结合在线热解-光电离质谱法研究了Li₂CO₃对松木催化热解过程的影响。热重分析结果表明,Li₂CO₃的掺入能够使松木热解向低温区移动,且不会显著增加焦炭的产量。在线热解-光电离质谱研究结果表明,松木的3种组分,纤维素、半纤维素和木质素,对催化剂Li₂CO₃的响应不同：纤维素和半纤维素主要热解产物产量有下降趋势,而木质素主要热解产物产量却明显上升;松木主要热解产物的最大生成速率时间和温度都有不同程度的减小。本实验结果表明,热解产物对催化剂的不同响应与它们自身结构有密切关系,在松木热解过程中,Li⁺能降低含氧热解产物的C-O键能从而促进裂解。     

超宽谱段覆盖探测器原型器件问世

<正>中科院上海技术物理研究所红外物理国家重点实验室王建禄、胡伟达等将具有热释电功能的铁电材料与低维半导体材料相结合,综合利用两类材料多机制耦合及多效应融合,研制出紫外-可见-短、中、长波红外超宽谱段覆盖的探测功能原型器件。红外探测技术在多个领域具有重要应用。目前,红外探测技术正朝着高灵敏、高分辨、宽光谱的方向发展。热探测器探测波长范围广,并具有室温工作及体积方面的优势。低维材料有独特结构和优异光电特性,用于光电器件在尺寸、功耗及灵敏度上     

超宽谱段覆盖探测器原型器件问世

<正>中科院上海技术物理研究所红外物理国家重点实验室王建禄、胡伟达等将具有热释电功能的铁电材料与低维半导体材料相结合,综合利用两类材料多机制耦合及多效应融合,研制出紫外-可见-短、中、长波红外超宽谱段覆盖的探测功能原型器件。红外探测技术在多个领域具有重要应用。目前,红外探测技术正朝着高灵敏、高分辨、宽光谱的方向发展。热探测器探测波长范围广,并具有室温工作及体积方面的优势。低维材料有独特结构和优异光电特性,用于光电器件在尺寸、功耗及灵敏度上     

光电离质谱结合GC/MS研究棉麻织物的热解

选取生物质类固体废弃物中的棉麻织物作为研究对象,利用热重、同步辐射真空紫外光电离质谱以及气相色谱-质谱联用技术研究其在低压环境中的热解过程。热重分析结果显示,半纤维素和木质素在麻布中的含量高于棉布中的。结合产物的光电离质谱图以及气质联用仪的实验结果对主要产物进行了定性分析,并研究了热解产物随温度的变化趋势,发现500℃下棉布的热解产物最多,而麻布由于含有较多的半纤维素和木质素成分,表现出较宽的热解温区。此外,热解产物中乙醇醛的含量极低,证明了它是纤维素的二次分解产物。     

钾对再造烟叶氧化热解行为的影响

为进一步了解钾对再造烟叶热解行为的影响,利用电渗析法脱除烟草浓缩液中的主要离子以减弱其他离子的干扰,并采用热重分析法研究钾对再造烟叶氧化热解行为的影响。结果表明:1离子化合物显著影响再造烟叶氧化热解过程,电渗析法可高效脱除烟草浓缩液中的主要离子,脱除率在90%以上;2钾显著影响再造烟叶低温氧化热解阶段,使该阶段整体向低温方向移动,同时热释放总量、峰值温度及对应的最大热释放速率均显著下降;3钾促进焦炭的形成,影响再造烟叶残炭氧化,且添加量起关键作用;低添加量的钾使该阶段峰值温度降低,最大热降解速率和质量损失升高,促进残炭氧化;高添加量的钾完全改变残炭氧化进程,主要质量损失和热释放阶段向高温方向移动,峰值温度大幅增加。     

韧性碳化硅/石墨复合材料

英国化学工业公司研制出一种韧性的层压碳化硅/石墨复合材料。该材料用石墨对碳化硅/聚合物糊料薄板进行涂敷而制成。涂敷的板然后迭层、压制、加热形成热解聚合物,接着在约2000℃烧结。任何裂坟     

热重-红外联用方法在煤质分析中的应用

利用热重-红外联用分析仪,对煤的工业分析、热解过程进行实验研究,同时用傅立叶变换红外光谱仪对挥发分产物进行了实时分析,使煤的工业分析结果、热解特性参数、热解产物分析在一次实验测定过程中同时获得.     

乘员舱非金属材料脱气物的GC／MS分析及评价

应用ＧＣ／ＭＳ联机和顶空／浓缩采样技术，对２１种国产聚合材料的热脱气产物进行了检测，定性鉴定出６９种化学成分，讨论了脱气物的来源和材料脱气的毒理学特征，初步评价了材料的卫生性能并提出合理使用聚合材料的建议，为评价和选用聚合材料提供一些实验依据。     

Imaging cells on polymer spherulites

Polymers are commonly used to construct tissue‐engineered medical products and the conditions used to process these polymeric materials can affect their biological performance. For semi‐crystalline polymers, thermal processing conditions can induce crystallization of the polymer chains into spherulites, which cause the polymer surface to become roughened. This change in surface topology can influence cell behaviours such as adhesion, morphology and proliferation. Herein, a simple microscope technique is presented, which combines fluorescence microscopy with transmitted white light microscopy using crossed polarizers. This technique allows simultaneous imaging of cells and polymer spherulites, which enables the biomaterials researcher to observe the effects of spherulites on cell alignment and morphology.     

Stone-based structural materials

Several stone-based structural materials are compared, including cement concrete, polymer cement concrete and a special type of granite-based polymer concrete called Granitan. The differences between the materials, particularly for machine-tool component applications, are discussed. It is shown how the inherent disadvantages of these stone-based materials, notably the high thermal expansion and creep, have been refined out of more recent formulations, by using different resins, more controlled structure and specific stones.     

Welding of tribologically optimized polyetheretherketone films with metallic substrates

A thermal impact welding process has been developed which allows the thermal joining of polyetheretherketone (PEEK) matrix materials with steel and aluminum substrates, respectively. The objective is to render manufacturing of innovative slide elements possible without the need for an up to now commonly used layer of sintered bronze in order to enhance the adhesion of the polymer. It is proven that excellent joining quality and wear resistance of the polymer layer can be achieved without sintered bronze.     

Evaluation of inhomogeneous deformation and stress concentration in polymer composites injection weld by means of thermoelastic techniques

Fiber composite materials are widely used in aerospace industries due to their high specific strength and stiffness. Especially, the increasing use of polymer composite materials for injection of automobile components has led to a considerable interest in the application of stress pattern analysis by thermal emission to these composite materials. Therefore, in this study the microstructure of glass fiber orientation at the parent and weld line of polycarbonate is observed by a light transmission microscope. And we also investigate a stress concentration model of a notch including short glass fibers. Especially the polymer injection weld reorients the fiber to suggest a new method for the evaluation of inhomogeneous deformation.     

Development of Vibrothermography as a Method for Nondestructive Testing of Products Made of Polymer Structural Materials with the Use of Forced Mechanical Vibrations

Russian Journal of Nondestructive Testing - One of the promising methods for thermal nondestructive testing of products made of polymer structural materials (PSMs) is vibrothermography, i.e., when...     

Analysis of thermal conductivity in HI-LEDs lighting materials

The present study devised a measurement system to estimate the thermal conductivity of electronic product materials, especially in HILEDs lighting materials, exhibiting distinct thermal characteristics by conducting thermal performance experiments and theoretical analyses. First, steady-state conduction analysis with thermal resistance method was investigated on three composite material substrates of unknown heat conduction coefficients through a substrate material named Bakelite of low thermal conductivity revealing stable quality. Second, one-dimension semi-infinite transient conduction analysis was utilized to investigate metal materials with high thermal conductivities. Results showed that the Bakelite experimental module was verified for 62.5 % of the original wattages, which closest to the thermal conductivity 0.233 W/m-K of the Bakelite. And these composite materials M1, M2 and M3 composed of polymer and epoxy were 1.311, 0.844 and 2.403 W/m-K, respectively. The thermal performance experiments were investigated and the results have proved the correctness of the theoretical model. According to the experimental results, calculating the temperature value of the metal materials comprising cotton insulation and the transient analysis, this study determined the temperature error to be less 20 %. Consequently, a transient measurement system and method for metal materials with high heat conduction coefficients was established. Finally, the results of this work are the useful thermal conductivity method to facilitate rapid analysis in the future.

     

Physicochemical processes in metal-polymer tribosystems

Physicochemical processes developing under friction interaction of polymer composite materials (PCM) with a metallic counterbody and their influence on the thermodynamic state of the tribosystem are analyzed. It is shown that tribochemical reactions and triboelectrical and thermal processes augment the tribosystem entropy. Mechanical loading and thermal processes have a dominant effect on the alteration of the thermodynamic state of the tribosystem.     

Determining the effects of thermal conductivity on epoxy molds using profiled cooling channels with metal inserts

Polymer injection molds are generally manufactured with metallic materials, such as tool steel, which provide reliable working of molds and extended service life. The manufacture of injection molds with steel is a prolonged process because of the strength of steel. For a short prototype production run, one of the suitable choices could be the use of aluminum-filled epoxy material, which can produce a functional mold in a short time as compared with a conventionally machined tool. Aluminum-filled epoxy tooling is a good choice for short production runs for engineering applications, yet works best for relatively simple shapes. The advantages in relation to the fabrication of injection molds with epoxy-based materials include time saving in producing the mold, epoxy curing at ambient temperature, and ease of machining and post processing. Nevertheless, one major drawback of epoxy material is its poor thermal conductivity, which results in a relatively longer cooling time for epoxy injection molds. This study investigates some of the innovative ideas for enhancing the thermal conductivity for epoxy molds. The basic concept behind these ideas was to embed a highly thermally conductive metal insert within the mold between cavities with an innovative design of cooling channels called profiled cooling channels. This technique will increase the effective thermal conductivity of the epoxy mold, leading to the reduction in cooling time for the injection molded polymer part. Experimental analysis conducted in the current study also verified that the mold with profiled cooling channels and embedded metal insert has significantly reduced the cooling time.     

Ultra-sensitive thermal conductance measurement of one-dimensional nanostructures enhanced by differential bridge

Thermal conductivity of one-dimensional nanostructures, such as nanowires, nanotubes, and polymer chains, is of significant interest for understanding nanoscale thermal transport phenomena as well as for practical applications in nanoelectronics, energy conversion, and thermal management. Various techniques have been developed during the past decade for measuring this fundamental quantity at the individual nanostructure level. However, the sensitivity of these techniques is generally limited to 1 × 10(-9) W∕K, which is inadequate for small diameter nanostructures that potentially possess thermal conductance ranging between 10(-11) and 10(-10) W∕K. In this paper, we demonstrate an experimental technique which is capable of measuring thermal conductance of ～10(-11) W∕K. The improved sensitivity is achieved by using an on-chip Wheatstone bridge circuit that overcomes several instrumentation issues. It provides a more effective method of characterizing the thermal properties of smaller and less conductive one-dimensional nanostructures. The best sensitivity experimentally achieved experienced a noise equivalent temperature below 0.5 mK and a minimum conductance measurement of 1 × 10(-11) W∕K. Measuring the temperature fluctuation of both the four-point and bridge measurements over a 4 h time period shows a reduction in measured temperature fluctuation from 100 mK to 0.6 mK. Measurement of a 15 nm Ge nanowire and background conductance signal with no wire present demonstrates the increased sensitivity of the bridge method over the traditional four-point I-V measurement. This ultra-sensitive measurement platform allows for thermal measurements of materials at new size scales and will improve our understanding of thermal transport in nanoscale structures.