生物材料冻干保护剂的热分析

生物材料冻干保护剂的玻璃化转变温度的测量对生物材料冻干保护剂的选择、冻干工艺的设计和贮存条件的选择有重要的指导意义.以海藻糖、蔗糖、乳糖、麦芽糖、葡萄糖等五种糖以及牛血清白蛋白作为生物材料的冻干保护剂,利用差式扫描量热法测量了保护剂溶液和保护剂冻干样品的玻璃化转变温度,研究了牛血清白蛋白的加入、糖的浓度、糖的种类等三种因素对保护剂溶液和保护剂冻干样品玻璃化转变温度的影响.     

固体热分解动力学的热分析法研究

以热分析法（ＴＧ、ＤＴＧ）为手段，对固态物质（聚丙烯（ＰＰ））在不同升温速率（５，１０，１５，２０℃／ｍｉｎ）下的热降解动力学进行了研究。用Ｓｅｓｔａｋ复杂机制进行非线性拟合处理，得到了聚丙烯降解反应在不同升温速率及不同转化率α下的活化能Ｅ、指前因子Ａ等动力学参数，参数的稳定性和重复性皆较好。活化能Ｅ＝１０５．４０±０．５ｋＪ／ｍｏｌ，与文献值相符，与反应机制有关的动力学参数ｍ、ｎ和ｐ分别为６．２１２８、７．６８１９和８．０２３８。还讨论了Ｓｅｓｔａｋ复杂机制在求解动力学参数中的优点     

一种共聚型聚酰亚胺成膜工艺的探究

采用溶液缩聚法通过共聚的方式合成得到了聚酰胺酸(PAA),PAA经过热酰亚胺化得到聚酰亚胺(PI)薄膜。重点讨论了成膜工艺中的升温速率对薄膜结构和性能的影响,分别以1、3、5、7和9℃/min的升温速率制备出5种PI薄膜。同时对薄膜进行了红外、X射线衍射、扫描电镜和综合热分析等表征。结果显示:不同升温速率得到的PI薄膜的结构和性能上均有明显的差异,其中以5℃/min升温速率制备的PI薄膜性能最优,具有最高的热分解温度,最高的玻璃化转变温度,最强的结晶度。     

聚氯乙烯／梯形聚苯基倍半硅氧烷共混物的相结构及流？…

由单螺杆挤出机制备了聚氯乙烯（ＰＶＣ）／梯形聚苯基倍半硅氧烷（ＰＰＳＱ）（１００／０、９５／５、９０／１０、８５／２０）机械共混物,通过扫描电镜（ＳＥＭ）观察了该共混物的相结构,富ＰＰＳＱ相形成２的球状颗粒较均匀地分散于ＰＶＣ的连续相中,ＰＶＣ／ＰＰＳＱ共混物的流动温度（Ｔｔ）均低于纯ＰＶＣ的Ｔｔ,而它们的玻璃化转变温度（Ｔｇ）略高于纯ＰＶＣ的Ｔｇ,随ＰＰＳＱ含量的增加,ＰＶＣ／ＰＰＳＱ共混物的Ｔ     

不同热历史间规聚丙烯的多晶型现象

以DSC、常温及变温WAXD手段相结合,研究了不同热处理条件诱导间规聚丙烯的多晶型现象.结果表明:等温熔体结晶s-PP在TC<110℃形成晶型Ⅱ,Tc≥110℃则晶型Ⅱ和晶型Ⅰ同时出现;等速降温熔体结晶所得s-PP为晶型Ⅰ、Ⅱ混合物,晶型Ⅱ、Ⅰ含量分别随降温速率升高而减小和增加;骤冷s-PP样品在10 K/min升温过程中,当T<70℃时以晶型Ⅱ堆积,继续升温有晶型Ⅱ-Ⅰ转变发生,此转变为吸热过程.     

FeCuNbVSiB纳米晶软磁合金及其在电力电子技术领域中的应用

报道了新开发的Ｆｅ７３．２Ｃｕ０．８Ｎｂ２Ｖ１．５Ｓｉ１．５Ｂ１１纳米晶合金的主要磁性能：μ０≥８×１０＾４,ＢＳ＝１．４０Ｔ,Ｐ０．５／２０ｋ≤１９Ｗ／ｋｇ,Ｐ０．５／５０ｋ≤９０Ｗ／ｋｇ。以μ（ｋ）ｔ Ｐ０．５／２０ｋ为参数,研究了合金的温度稳定性。研究表明,与２５℃时全金性能相比,在－５０℃和＋５０℃时合金性能的相对变化率不超过５％。介绍了合金在中、高频功率变压器、传感器、电感器等电力电子技     

氰酸酯MCE-085树脂固化行为和浇铸体性能研究

对氰酸酯MCE-085树脂分别在5K/min、10K/min和15K/min升温速率下的固化过程进行分析,利用外推法制定了树脂的固化制度为175℃/6h+220℃/2h。制备的氰酸酯MCE-085树脂浇注体的拉伸强度为29.1MPa,压缩强度为88.8MPa,压缩模量为2.90GPa,弯曲强度为40.6MPa,弯曲模量为2.93GPa,玻璃化转变温度为241.9℃,900℃时的残碳率为20.75。树脂在75～145℃温度范围内黏度800mPa·s,在85℃、90℃和100℃3个温度的等温过程中一直保持满足RTM工艺的低黏度平台。     

旋转CVI制备C/SiC复合材料

旋转 ＣＶＩ是在 ＣＶＩ原理基础上发展的一种制备 Ｃ／ＳｉＣ复合材料的新工艺,通过石墨衬底的旋转,使预制体的制备与基体的沉积同步进行,能有效消除一般ＣＶＩ工艺过程中存在的“瓶颈”效应．在自制的旋转 ＣＶＩ设备上实验,探索了旋转 ＣＶＩ工艺参数中 ＣＨ_３ＳｉＣｌ_３（ＭＴＳ）的流量与浓度、沉积温度和Ｃ布缠绕线速度对ＳｉＣ基体沉积速度,以及沉积温度对基体结构的影响．并在低压（５ｋＰａ）、高温 （１１００℃）、 ４００ ｍＬ·ｍｉｎ^－１ Ｈ_２、 ２００ ｍＬ·ｍｉｎ^－１Ａｒ、 ＭＴＳ４０℃与Ｃ布以１．１～３．５ｍｍ·ｍｉｎ^－１的线速度连续旋转的沉积条件下,实现了单丝纤维间微观孔隙、纤维束之间以及Ｃ布层间宏观孔隙的致密化同步完成．     

CuZnAlMnNi形状记忆合金马氏体相变焓的研究

采用差示扫描量热分析技术在５℃／ｍｉｎ以及在超低降温速率下，研究了ＣｕＺｎＡｌＭｎＮｉ形状记忆合金马氏体相变的热焓。通过实验和计算，由母相向马氏体转变时单位质量的相变总焓、热容改变焓和马氏体相变焓分别是３．２２Ｊ／ｇ、１．８８Ｊ／ｇ和１．３４Ｊ／ｇ。     

VO2薄膜的主要制备工艺参数研究

通过正交试验设计对制备ＶＯ２薄膜过程中的部分影响因素（膜厚，最终热处理温度和热处理保温时间）进行了分析研究。ＶＯ２薄膜由无机溶胶－凝胶法制备Ｖ２Ｏ５凝胶膜经真空热处理而成。试验结果表明，ＶＯ２薄膜的最终电学性能明显受到膜厚、热处理温度和保温时间的影响。其中以热处理温度的影响最为显著。当真空度为３Ｐａ、升温速率为２℃／ｍｉｎ时，在试验参数范围内（真空热处理温度３４０￣５００℃，保温时间４０￣２４０ｍ     

降温速率对脂质体冻干品质量影响的实验研究

脂质体冻结过程中形成的冰晶不仅会对脂质体囊泡造成损伤,而且会影响热量的传递和水蒸气的逸出。研究了含有海藻糖的脂质体悬浮液在不同的降温速率下的冻干品质量,比较了不同降温速率下冻干脂质体的温度变化曲线和含水量变化曲线,及冻干脂质体复水后的囊泡粒径变化。结果表明,对于脂质体快速冻结后得到的冻干品质量优于慢速冻结。     

Microwave-assisted rapid discharge sintering of a bioactive glass�Cceramic

Bioactive glass-ceramics have been developed as successful bone graft materials. Although conventional sintering in an electrically-heated furnace is most commonly used, an alternative microwave plasma batch processing technique, known as rapid discharge sintering (RDS), is examined to crystallise the metastable base glass to form one or more ceramic phases. Apatite-mullite glass-ceramics (AMGC) were examined to elucidate the effects of RDS on the crystallization of a bioactive glass-ceramic. By increasing the fluorine content of the glass, the fluorapatite (FAp) and mullite crystallization onset temperatures can be reduced. Samples were sintered in a hydrogen and hydrogen/nitrogen discharge at temperatures of ≈800 and 1000 °C respectively with the higher sintering temperature required to form mullite. Results show that the material can be densified and crystallised using RDS in a considerably shorter time than conventional sintering due to heating and cooling rates of ≈400 °C/min.     

Preparation, characterization, and stability of liposome-based formulations of mitoxantrone

The preparation, characterization, and stability of lyophilized liposome-based formulation of mitoxantrone was investigated. Mitoxantrone was entrapped inside small, unilamellar liposomes composed of dioleoylphosphocholine (DOPC), cholesterol, and cardiolipin. The mean vesicle size and drug entrapment efficiency of the liposomes were ~ 150 nm and ~ 99%, respectively. Less than 1% of drug was lost and mean vesicle size remained unchanged after sterile filtration. The pre-lyophilized (pre-lyo) formulations were characterized by a differential scanning calorimetric (DSC) method. Results showed that the glass transition temperatures (Tg') increased as the molar ratios of sucrose:lipid and trehalose:lipid in the formulations were increased. The maximum Tg' of the pre-lyo formulations containing 10:1 sucrose:lipid and trehalose:lipid molar ratios were - 37°C and - 41°C, respectively. After reconstitution of the lyophilized cake of the sucrose-containing formulation, the mean vesicle size was comparable to pre-lyo liposome size. In vitro release studies showed that less than 2% of mitoxantrone was released after an extensive dialysis against phosphate buffered saline (PBS) at 37°C, indicating that the mitoxantrone was highly associated and retained inside the liposomes. Short-term stability studies of the sucrose-containing formulations revealed that the reconstituted and eight-fold diluted formulations were stable for up to 8 hours at room temperature. Long-term stability studies of lyophilized liposomal mitoxantrone showed that the lyophilized formulation was stable for up to 13 months after storage at refrigerated condition.     

Growth and calorimetric measurements on CsLiB6O10

Single crystals of cesium lithium borate (CLBO) were grown from stoichiometric melt, as well as from B₂O₃ deficient flux. Calorimetric measurements performed on the grown crystals show that the material transforms to glassy phase from the molten phase even at cooling rates as low as 1 °C/min. The transformation to the crystalline phase from the glass phase does not occur during the heating cycle in the DTA experiments. In order to estimate the onset of crystallization temperature of CLBO glass and ensure the appearance of crystallization peak during heating cycle, a new approach (seeded crystallization) was adopted in the DTA experiments. The onset of seeded crystallization temperature shows a strong dependence on the heating and cooling rates. The activation energy of seeded crystallization determined by Kissinger method turns out to be 3.07 eV. The ergodicity making (EM) of the glass transition as seen from the DSC measurement is ∼ 424 °C for a heating rate of 5 °C/min. Microscopic examination suggests that the glass CLBO transforms to crystalline phase via. dendrites.     

Zr65Al7.5Ni10Cu15Co2.5合金的玻璃转变温度

根据Ｚｒ６５Ａｌ７。５Ｎｉ１０Ｃｕ１５Ｃｏ２。５合金的纳米晶，晶体，液体和玻璃比热的测量结果，研究了合金的玻璃转变温度与全金的热力学函数，动力学参数以及加热速度的关系。结果表明，非晶态合金玻璃转变所需转变激活能很小，玻璃转变温度实际上是由于加热速度引起的不同状态的玻璃与液体的热力学平衡温度。     

Comparison between DSC and TMDSC in the investigation into frozen aqueous cryoprotectants solutions

Purpose: The influence of thermal parameters in the observation of thermal events and in the calculation of heat transformation in aqueous cryoprotectant solutions after freezing was investigated using conventional differential scanning calorimetry (DSC) and temperature-modulated DSC (TMDSC), respectively. Methods: The systems under study were formed by pure water and diluted aqueous solutions of mannitol, trehalose, sucrose, sorbitol, and glycine. The influence of different combinations of frequency and amplitude was analyzed in heating–cooling and heating-iso TMDSC scans. Results: Trehalose, sucrose, and sorbitol present a lesser critical temperature of primary drying than other cryoprotectants studied. The calorimetric variables selection is crucial to detect or not the thermal events, or to detect so with different numerical values. Then, the values of the calorimetric parameters determined are different if measured in a mode of heating–cooling or heating-iso. The TMDSC method-1 used in this study employs a higher number of cycles in each thermal event. The use of Lissajous figures and the study of the C_{p in-phase} signal evolution will allow us to understand the complexity of the events detected. Conclusions: The comparative study of both techniques points to the selection of conventional or modulated technique depending on the type of system and the nature of the studied events.     

PLLA/CNTs复合材料的非等温冷结晶

通过溶液共混法制备了聚乳酸/碳纳米管(PLA/CNTs)复合材料,并利用差示扫描量热分析(DSC)研究了CNTs的种类、长度、直径和质量分数对不同升温速度下PLA非等温冷结晶性能的影响,结果表明,PLA/CNTs复合材料的玻璃化转变温度(Tg)和结晶峰温度(Tc)都随升温速度降低而逐渐降低,而结晶度和熔融温度(Tm)则升高。添加质量分数为0.1%的多壁碳纳米管(MWNTs)即可有效促进PLA的异相成核,提高其结晶速度和结晶度,以10℃/min升温冷结晶时,当CNTs用量达1%时会阻碍PLA的非等温结晶过程,并导致PLA复合材料的Tg、Tm和结晶度降低。MWNTs对PLA非等温结晶的促进作用比SWNTs或DWNTs明显,而较短的MWNTs比长MWNTs的作用略为明显。     

Glass-forming region and DTA survey of some glasses in the Si-Ge-As-Te threshold switching glass system

The glass forming region for 2.0 g melts in the Si-As-Te system and pseudo ternary Si 5%-Ge-As-Te and Si 10%-Ge-As-Te systems are reported together with glass transition temperatures and metastable glass melt crystallisation temperatures for bulk glass pieces of different compositions heated at 20°C/min under standardised conditions in a nitrogen atmosphere.     

添加AlN对机械合金化Zr65Al7.5CU17.5Ni10非晶态合金热稳定性的影响

以成分为Zr65Al7.5Cu17.5Ni10的元素的粉末混合物及AIN颗粒为起始材料,经机械合金化形成非晶态合金为基体的复合材料,AIN添加量为5％－30％（体积分数,下同）,利用X射线衍射（XRD）,透射电子 显微镜（TEM）和差示扫描量热计（DSC）分析了含AIN复合材料的结构特性,玻璃转变与晶化行为,TEM观察表明,AIN第二相粒子弥散分布在晶Zr基合金基体上,粒子尺寸为20－200nm,仍为初始的晶体结构,与未添加AIN的Zr基非晶态合金相比,含5％－10％AIN的复合材料仍表现出较宽的过冷液态温度区域,玻璃转变温度（Tg)和晶化激活能（Ex)没有显著变化,但晶化起始温度（Tx)向高温移动大约10K,导致过冷液态温度区域的扩宽,AIN含量增至30％,明显的玻璃转变消失,Tx升高的20K。     

Modulated-temperature differential scanning calorimetry and Raman spectroscopy studies of AsxS100−x glasses

Thermal properties of chalcogenide AsxS100–x glasses in the glass transition region have been studied by modulated-temperature differential scanning calorimetry (MTDSC). All samples in this work were given the same thermal history by heating to a temperature above the glass transition, equilibrating and then cooling at a rate of 5°C/min to a temperature of 20°C. The reversing and non-reversing heat flows through the glass transformation region during both heating and cooling schedules were measured and the values of the parameters Tg, H, Cp and Cp, which characterize the thermal events in the glass transition region, were determined as a function of the glass composition. The structurally determined parameters Tg, H, Cp and Cp reveal major extrema when the composition of AsxS100–x glass becomes As40S60, that is the same as the composition of the corresponding stoichiometric compound. In addition, we observe small thresholds in these properties at 28.5 at % As (As28.5S71.5) around the same composition as that reported in the As-Se glasses. No such thermal analysis had been done on the AsxS100–x glasses previously. It is shown that AsxS100–x glasses where x < 25 at % As are formed from two glass phases. From MTDSC measurements, it was possible to establish the probable composition of the high temperature glass phase and from Raman spectroscopy it was possible to correlate the MTDSC results with the structure of the As-S glasses.