聚酯材料的温度调制式DSC分析

采用温度调制式DSC技术 (简称ADSC) ,研究了聚酯热性能的测试方法。结果表明 ,ADSC仪器参数的选择对实验结果会有很大的影响 ,对于DSC82 2e型仪器 ,选择平均加热速率 1.5℃ /min ,调制振幅± 1℃ ,调制周期 180s时 ,可获得较好的结果。用ADSC分析聚酯试样可分开PTT可逆玻璃化转变和不可逆应力松弛峰 ,可分开PBT不可逆冷结晶峰与可逆玻璃化转变 ,从而得到Tg 和准确冷结晶焓 ;可准确测定PET和PBT的初始结晶度 ;用相位角变化可测定微弱的玻璃化转变 ,具有较高的灵敏度     

Thermal characterisation of polymeric systems by mass spectrometry

The utility of mass spectrometry as a technique for the characterisation of polymeric formulations is discussed in general terms. The use of thermal techniques in which sufficient energy is given to the system to liberate volatile components of the formulation and, in some cases, to induce small amounts of polymer degradation, is described. Results obtained using this technique for a variety of polymer systems are discussed and the advantages of using this approach outlined. Recent developments in field desorption-mass spectrometry for the direct characterisation of modern polymer systems are discussed and some early results presented.     

Exactly alternating silarylene—siloxane polymers: 6. Thermal stability and degradation behaviour

The thermal stability and degradation behaviour of a series of twelve different exactly alternating silarylene—siloxane polymers were investigated by several different methods including thermal gravimetric analysis (t.g.a.) in air and in nitrogen, long term (up to 48 h) high temperature (600° and 900°C) isothermal degradation in nitrogen, and rapid pyrolysis in helium. No weight loss was observed by t.g.a. until about 400°C, and two distinctly different mechanisms were observed, one for degradation in nitrogen (a single step process), and the other in air (a three step process). Under nitrogen, black, insoluble, carbon-hydrogen-silicon containing degradation products were obtained, which were stable in pure oxygen to at least 1100°C. In air, pure SiO₂ was obtained after heating to above 730°C. Isothermal investigations revealed that at temperatures of 600°C and above, weight loss by thermal degradation under a nitrogen atmosphere was completed in less than an hour, and the polymeric products which remained thereafter did not change any further even after 48 h at 900°C.     

内窥式热像仪在玻璃熔窑中的应用

介绍了内窥式热像仪的特点和技术参数。通过在我司某条浮法玻璃熔窑安装试用内窥式热像仪后,证明其能够实现熔窑内玻璃液温度测量控制、熔化工艺监控、熔窑保护和节能减排等功效,可以在浮法玻璃熔窑监控中推广应用。     

三聚氰胺甲醛树脂泡沫塑料碳化研究

摘要：以三聚氰胺甲醛树脂泡沫塑料为前驱体进行碳化研究。通过实验可以看出,三聚氰胺甲醛树脂泡沫材料密度和压陷硬度随温度的升高先有所上升后逐渐降低,体积收缩比较明显,但仍具有一定的弹性;采用扫描电子显微镜观察到随着温度的升高,泡沫塑料泡孔逐渐萎缩、骨架变细更容易断裂;利用同步热分析仪记录了泡沫塑料碳化过程质量损失情况,在400～800℃三聚氰胺甲醛树脂泡沫碳化速率最快;借助全自动元素分析仪分析了三聚氰胺甲醛树脂泡沫材料各元素相对含量的变化趋势,在20～700℃之间,泡沫中N元素相对含量先增加后降低,C元素相对含量在300℃后显著增加。     

Thermal and Structural Analysis of Natural Fiber Reinforced Starch-Based Biocomposites

This is the second part of a series of articles dealing with characterization of starch based biodegradable composites. Potato, sweet potato, and corn starch varieties were used as matrices of the biocomposites. Natural fibers including jute, sisal, and cabuya were used as discrete reinforcement. Water and glycols were used as plasticizers. Compression molded specimens were prepared and characterized by a variety of techniques. Differential Scanning Calorimetry (DSC) and Thermogravimetry (TGA) were used to characterize the thermal behavior of these composites. Processed specimens did not show the typical endothermic peak observed in DSC scans for native starch powder. No significant difference was observed for weight loss and decomposition due to fiber or plasticizer content among the different specimens. Attenuated Total Reflectance–Infrared Spectroscopy (ATR-IR) was used to characterize the starch compounds and the effect of plasticizers and reinforcing fibers. The spectra found for most specimens were consistent with those of pure starch. Scanning electron microscopy (SEM) pictures showed the morphology of the specimens for different types of starch matrices and different fiber contents.     

二氯丙烯胺的热分解动力学

用热分析的方法研究了二氯丙烯胺的热分解动力学,起始分解温度在120℃左右,并用无模式函数法计算出反应活化能、指前因子。     

过渡元素硅钼钨多元取代多金属含氧簇合物的热分析研究

利用热重-差热分析,变温IR光谱和变温X-射线粉末衍射等方法,对所合成的过渡元素硅钼钨多元取代多金属含氧簇合物的热稳定性进行了研究。结果表明,所合成的化合物的分解温度在320～380℃,不同的过渡元素取代对所合成的多金属含氧簇合物热稳定性没有显著影响,其热稳定性随钨的增加而增强。     

炼焦过程温度变化的控制研究与实践

炼焦过程中,煤饼在炭化室内经历了一系列的物理变化,并发生了大量的化学反应。在不同阶段,随着大量的吸热和放热反应,由此影响了各燃烧室的温度。结合生产实际,在研究和总结燃烧室温度变化规律的基础上,指引生产调控,并以此提高炉温的管控水平,实现生产过程的节能降耗。     

热膨胀系数简易测量装置研制及若干材料测量

以液氮为冷源,研制了一套基于千分测微器的材料热膨胀系数简易测量装置,能够测量80~353 K温区各类固体材料的热膨胀系数,可重复性高于99.3%,不确定度小于3.34%。通过将T1紫铜、6060铝、304不锈钢、尼龙、G10环氧树脂等典型材料热膨胀系数测量数据与文献数据比较,发现两者最大相对偏差小于6.0%,80~353 K温区的平均偏差约为3.1%。在此基础上,测量并获得了高低温热环境工程等应用场合常用到的其他一些材料如殷钢、6262铝、316不锈钢、45钢、聚四氟乙烯、ABS塑料等的热膨胀系数数据。     

明胶软胶囊干燥特性的研究

在对流干燥实验台上进行了明胶软胶囊干燥特性的实验,研究了加热空气温度、风速、湿度对干燥过程的影响规律。实验结果表明,提高加热空气的温度,虽然提高了传热速率,但在第2降速阶段干燥速率下降,导致最终含水质量分数反而偏高;随着加热空气风速的提高,传热速率增加,干燥速率在第1降速阶段呈现加快趋势,软胶囊的最终含水质量分数稍有降低;而加热空气湿度的变化,对传热过程影响很小,但随着加热空气湿度的降低,干燥速率提高,使得最终含水质量分数明显降低。通过研究软胶囊的干燥特性,为制药工业中软胶囊的生产提供合理指导,对优化干燥过程、降低能耗、提高产品质量和经济效益具有重要意义。