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21世纪的高分子化学展望 总被引:18,自引:0,他引:18
对于21世纪高分子科学的展望大致如下:21世纪的特征是能源、材料和环保与健康(或称绿色)。作为材料领域中极其重要的部分,21世纪对高分子材料在质量方面都有要求,大致可分二个方面同是通过控制聚合而得均匀高分子,其分子量概念不再是各种长短不齐高分子链的平均分子量;二是绿色高分子与绿色反应,前者主要是指生物高分子,对环境稳定高分子则将进行回收与重复使用;所谓绿色反应指所有高分子与相应单体的合成方法都必须 相似文献
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利用高压差示扫描量热法(PDSC)研究了典型抗氧剂T501(2,6-二叔丁基对甲基苯酚)、L135(高分子量液体酚)、L57(辛基/戊基二苯胺)和T531(N-苯基-α萘胺)对复合磺酸钙基润滑脂氧化安定性的影响,考察了抗氧剂浓度对抗氧化效果的影响。结果表明,PDSC是一种快速简便评价润滑脂氧化安定性的方法,适用于抗氧剂的筛选。与传统的旋转氧弹氧化法相比较而言,PDSC的评价结果更科学,更具有规律性。另外,根据阿仑尼乌斯公式计算了润滑脂氧化反应的表观活化能。 相似文献
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高压差示扫描量热法评价抗氧剂对润滑油基础油氧化稳定性的影响 总被引:1,自引:0,他引:1
结合环境友好润滑油产品的开发工作,利用高压差示扫描量热法(PDSC)研究了3种典型抗氧剂T501(2,6-二叔丁基对甲基苯酚)、T531(N-苯基-α-萘胺)和DNA(二壬基二苯胺)对菜籽油氧化稳定性的影响,并考察了浓度对抗氧剂作用效果的影响。结果证明,PDSC是一种快速简便评价基础油氧化稳定性的方法,适用于抗氧剂的筛选工作。另外,根据阿仑尼乌斯公式计算了不同油样氧化反应的表观活化能。 相似文献
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通过差示扫描量热仪(DSC)和热失重分析仪(TGA)测定了二氢杨梅素(DMY)的热稳定性。测定了添加DMY的不同高分子材料的氧化诱导温度(OIT*),并与添加相同质量分数工业抗氧剂Irganox B215的样品进行了比较。实验结果表明,DMY在230℃以下稳定性良好,可用于加工温度低于230℃的各种高分子材料的加工过程,添加DMY的各种高分子材料的抗氧化性能优于添加Irganox B215的样品。对其抗氧化作用机理分析表明,DMY的特殊结构,特别是分子中羟基的数量和位置是其具有强抗氧剂性的根本原因。DMY无毒、高效,有望作为新型天然抗氧剂得到广泛应用。 相似文献
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全息高分子材料通常是指基于相干激光技术制备,能够同时存储光波振幅、相位等全部信息的结构有序高分子材料,在裸眼三维显示、增强现实、高端防伪、高密度数据存储等高新技术领域具有重要应用价值.高性能化与多功能化是全息高分子材料的发展方向,正交反应设计提供了有效途径.本文简要介绍正交反应的概念、设计原理及在高分子材料先进制造中的应用,重点论述正交反应设计对于优化全息高分子材料加工工艺、提高折射率调制度和光栅衍射效率、降低雾度、抑制聚合反应引起的体积收缩、增加全息数据存储容量及构筑全息/发光双重图像功能新材料的重要性.为获得高性能多功能全息高分子材料,亟需发展更加丰富的正交反应体系. 相似文献
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GPC-多检测联用技术测定聚己内酯分子量及其分布 总被引:1,自引:0,他引:1
介绍一种用于生物可降解高分子材料聚已内酯(PCL)及其改性高分子的分子量和分子量分布测定的GPC-示差折光(RI)-示差黏度(DV)-直角光散射(RALLS)多检测联用技术.叙述了该方法的实验原理,并对测试过程中的有关技术及实验结果进行了讨论.该方法可准确测定聚己内酯(PCL)及其改性高分子的分子量及其分布、特性黏度分布、Mark-Houwink方程系数以及高分子尺寸等重要参数.通过对窄分布PS标样验证,分子量测定结果的相对误差在1%之内. 相似文献
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A. V. Tvardovskii A. A. Fomkin Yu. I. Tarasevich I. G. Polyakova V. V. Serpinskii I. M. Guseva 《Russian Chemical Bulletin》1992,41(6):987-991
The changes in the thermodynamic functions of the sorbents were calculated for the first time from measurements of the deformations of vermiculite during the sorption of water vapor and adsorption-calorimetric data.Institute of Physical Chemistry, Russian Academy of Sciences, 117915 Moscow. Institute of Colloid Chemistry and the Chemistry of Water, Academy of Sciences of the Ukraine, 252180 Kiev. Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 6, pp. 1270–1275, June, 1992. 相似文献
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We have summarized results of many experimental investigations of the thermodynamics of ionization of H2O(liq.) from 0–300°C and from 1.0 atm to nearly 8000 atm. Results of these investigations (equilibrium constants, enthalpies of ionization, heat capacities, partial molal volumes, and compressibilities) have been used for a number of thermodynamic calculations. It is particularly noteworthy that it is possible to use thermal data from 0–145°C with an equilibrium constant for 25°C in calculating reasonably accurate equilibrium constants for temperatures as high as 300°C. Similarly, it is possible to use volumetric data that refer to 1.0 atm in calculating useful equilibrium constants that apply for pressures as high as 2000 atm.Much of the work reported here was done while the author was on leave at the University of Lethbridge. 相似文献
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W. Zielenkiewicz A. Zielenkiewicz K. L. Wierzchowski 《Journal of solution chemistry》1993,22(11):975-981
Enthalpies of solution in water H
sol
o
and enthalpies of sublimation H
sub
o
were determined for a number of crystalline derivatives of uracil: 1,6-dimethyluracil (m
2
1,6
Ura), 1,3,6-trimethyluracil (m
3
1,3,6
Ura), 6-ethyl-1,3-dimethyluracil (e6m
2
1,3
Ura), 6-propyl-1,3-dimethyluracil (pr6m
2
1,3
Ura) and 6-butyl-1,3-dimethyluracil (but6m
2
1,3
Ura). Standard enthalpies of hydration H
hydr
o
and standard enthalpies of interaction H
int
o
of the solutes with their hydration shells were calculated. The data obtained show that dependence of H
int
o
on the number of-CH2- groups of n-alkyl chain added upon substitution of diketopyrimidine ring is nonlinear. This finding is discussed in connection with results of X-ray diffraction structure determinations for the crystalline compounds. 相似文献
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G. Venkoba Rao M. Balakrishnan N. Venkatasubramanian P. V. Subramanian V. Subramanian 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1):83-85
Abstract The signals for the α, β, and γ protons of pyridine exhibit a downfield shift in DMSO-d6, compared to CCl4 as solvent, the order being γ > β > α. This is attributed to an interaction between the positive end of the DMSO dipole and the lone pair of electrons on the ring nitrogen. This effect is also reflected in the faster rate of alkaline hydrolysis of ethyl isonicotinate over ethyl nicotinate and ethyl picolinate in aqueous DMSO relative to aqueous ethanol. Similar solvent effects are also observed in the pmr spectrum of pyrazine. 相似文献
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The protonation of leucoemeraldine in power form and in N-methylpyrrolidinone (NMP) solution by HCIO4 and HBF4 has been studied by x-ray photoelectron spectroscopy (XPS), infrared (IR), and ultraviolet (UV)-visible absorption spectroscopy. In powder form, less than 25% of the amine nitrogens can be protonated in the absence of oxygen. The effects of oxygen on the degree of protonation and the distribution of amine and imine units upon deprotonation of the salt are investigated. The degree of protonation in leuccemeraldine can be increased to about 50% with 3 M HCIO4, similar to that achievable with emeraldine base in powder form. In NMP solution, leucoemeraldine is easily oxidized by dissolved oxygen. Protonation of both leucoemeraldine and emeraldine base in NMP solutions results in metastable species which gradually undergo deprotonation. The resulting products are affected by the O2 content of the solutions. © 1993 John Wiley & Sons, Inc. 相似文献
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Earl M. Woolley John O. Hill William K. Hannan Loren G. Hepler 《Journal of solution chemistry》1978,7(5):385-393
We have made calorimetric measurements of enthalpies of dilution of aqueous iodic acid and have used these results for evaluation of the standard enthalpy of ionization of HIO3(aq.). We have also made calorimetric measurements of enthalpies of addition of perchloric acid solution to aqueous solutions of KIO3, KNO3, NaIO3, and NaNO3 and have used these results to obtain further values for the standard enthalpy of ionization of HIO3(aq.). On the basis of all these results, we have selected Ho=–660±125 cal-mole–1 as the best available standard enthalpy of ionization of HIO3(aq.) at 298.15°K, compared to the previously accepted –2400 cal-mole–1. Using the best available K=0.157 for ionization, we also obtain Go=1097 cal-mole–1 and So=–5.9 cal-oK–1-mole–1 for ionization of HIO3(aq) at 298.15°K.On study leave from Department of Inorganic and Analytical Chemistry, LaTrobe University, Bundoora, Victoria, 3083, Australia, to University of Lethbridge.On study leave from Department of Chemistry, University of Wollongong, Wollongong, N.S.W. 2500, Australia, to University of Lethbridge. 相似文献
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Sergey P. Verevkin Wei-Hong Peng Hans-Dieter Beckhaus Christoph Rüchardt 《Structural chemistry》1996,7(5-6):397-404
The standard enthalpies of combustion c
H
o of aliphatic diacetates1 and aromatic diacetates2 were measured calorimetrically. The enthalpies of vaporization vap
H
o or sublimation sub
H
o of1 and2 were obtained from the temperature function of the vapor pressure measured in a flow system. From f
H
o(g) of1 and2 new values of group increments for the estimation of standard enthalpies of formation of these classes of compounds were derived. The geminal interaction energy between the geminal acyloxy groups shows no anomeric stabilization.Geminal Substituent Effects, Part 12, for part 11 see Ref. 7. 相似文献
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An equation for the internal pressure acting on an adsorbate in micropores was obtained on the basis of the assumption that the chemical potential of an adsorbate in micropores is equal to that in an equilibrium gas phase and using the Dubinin-Radushkevich equation. The empirical relation between the characteristic adsorption energy and the half width of pores was expressed in terms of internal pressure and diameter of adsorbate molecules. The two-dimensional pressure was calculated for micropores with plane-parallel walls, where the width of a micropore coincides with the diameter of an adsorbate molecule. The results obtained were compared with the two-dimensional pressure of a monolayer on a free planar surface for an adsorbate and adsorbent of the same nature.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 1928–1930, October, 1995. 相似文献
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根据盐类水解关系式和水的离子积计算公式,建立了计算盐类水解度和水解产物离解常数的完全方程式。计算值同实验值比较,钾明矾溶液水解度平均偏差为0.6%,离解常数pK_b=11.6±0.1,水的离子积pK_w平均偏差小于0.06,从而改进了苏联的计算公式。 相似文献