利用时间外延法预测硫化胶常温扯断伸长率变化的方法研究

测试了NR，NBR和CR等6种硫化胶长达34年的室内自然老化（扯断伸长率变化）数据，利用前3年内试验数据建立了P－t二元数学模型来预测硫化胶在34年不同时间的扯断伸长度变化，并与试验数据进行了对比，两者较之吻合，证明利用时间外延法预测硫化胶常温下扯断伸长率变化是可行的。     

16种实用配方硫化胶长期室内自然老化压缩永久变形变化及预测

对用于丁腈橡胶、天然橡胶、氟橡胶、硅橡胶和三元乙丙橡胶等16个实用配方硫化胶试样进行了各种状态下30个室内自然老化试验，测量了20a至33a之久的压缩永久变形，并讨论了变化结果。用16种配方硫化胶试样的30个室内自然老化前期压缩永久变形的数据变化进行预测长期变化结果，并与实测长期老化结果进行对照，结果表明2者的符合程度较好，预测方法可行。     

16种实用配方硫化胶长期室内自然老化压缩永久变形变化及预测

对用于丁腈橡胶，天然橡胶，氟橡胶，硅橡胶和三元乙丙橡胶等16个实用配方硫化胶试样进行了各种状态下30个室内自然老化试验，测量了20a和33a之久的压缩永久变形，并讨论了变化结果。用16种配方硫化胶试样的30个室内自然老化前期压缩永久变形的数据变化进行预测长期变化结果，并与实测长期老化结果进行对照，结果表明2者的符合程度较好，预测方法可行。     

几种硫化丁腈橡胶常温化学应力松弛行为的研究

利用叠合曲线方法研究了三种硫化丁腈橡胶分别在空气，８＃润滑油，１０＃和１２＃液压中油中的常温化学应力松弛行为，叠合曲线是根据６０－１００℃下的试验数据构成的，其转换因子按作者提出的公式计算，常温叠合曲线的前一段已为２０年以实际自然老化数据所验证。叠合曲线表明，常温化学应力松驰是一个非常缓慢的过程。     

3种丁腈橡胶硫化胶加速老化与室内自然老化压缩应力松驰变化

用以丁腈-18和丁腈-26两种生胶为基材的3种实用丁腈硫化胶进行了5种温度的高温加速老化和室内自然老化。用压缩应力松驰系数作为老化性能变化指标,得出了性能随老化时间和温度变化的动力学曲线。用加速老化的数据进行了外推预测处理,得出了室内自然老化等效温度下的性能变化预测方程,并与实际室内自然老化18年的结果进行对照,同时给出了室内自然老化18年的物理性能变化结果。     

硫化时间及硫化体系对粘土胶热氧老化性能的影响

用热空气老化试验和热分析法讨论了硫化时间和硫化体系对粘土胶热氧老化性能的影响。结果表明,粘土胶由于热氧性能敏感,在硫化曲线允许的范围内,硫化时间以２０ｍｉｎ为宜。采用有效硫化体系和半有效硫化体系硫化粘土胶可以使其具有较好的热氧老化性能。     

DCP硫化HNBR压缩永久变形性能的研究

对比了氢化丁腈橡胶(HNBR)分别以DCP单用,DCP/硫黄并用,DCP/三烯丙基异氰酸酯(TAIC)并用作硫化体系的3个硫化结果,并分析了压缩永久变形随硫化体系变化的规律及硫化性能与压缩永久变形之间的关系。结果表明:DCP单用且用量较大时,HNBR压缩永久变形较差,最小值为41.9%;DCP/硫黄并用时,HNBR压缩永久变形优良,DCP4.5份和硫黄1.0份,压缩永久变形最小为22.0%;DCP/TAIC并用时,有效降低了压缩永久变形,TAIC用量的增加对HNBR压缩永久变形影响较小,当TAIC为1.0份时,压缩永久变形最小为28.9%。     

M204和M209-7硫化胶在推进剂中的老化性能变化预测

进行了乙丙胶M204和M209-7在推进剂中的加速老化试验，经过对试验数据的处理。初步发现时间外延方法适用于预测橡胶材料在特种介质中的老化性能变化。     

不同温度下杜仲胶/天然橡胶共混硫化胶的拉伸性能及应力松弛

将杜仲胶(EUG)与天然橡胶(NR)进行共混硫化,考察了不同EUG含量以及温度对硫化胶的拉伸性能和应力松弛的影响。结果表明,室温下EUG质量分数超过20%会形成结晶,随EUG质量分数逐渐增加到50%,硫化胶的断裂伸长率和拉伸强度均有不同程度下降;随温度升高,EUG晶区熔融,硫化胶抵抗形变能力降低,形变能力增强。在较高温度下,随EUG含量增加,硫化胶应力松弛的初始模量以及松弛到平衡值时的模量增大;随温度升高,应力松弛的初始模量以及松弛到平衡值时的模量减小。应用分数阶导数Kelvin模型对应力松弛曲线进行拟合,发现随温度升高,硫化胶体系中弹性部分减少而黏性部分增加,松弛时间缩短。     

Anomalous behavior of cured epoxy resins: Density at room temperature versus time and temperature of cure

The room temperature density (ρ_RT) of a difunctional aromatic epoxy resin cured with a tetrafunctional aromatic amine passes through a maximum value in the vicinity of gelation with increasing conversion. For a given cooling rate cure resutls in a unique value of ρ_RT for each conversion as long as the material does not vitrify on cure. The occurrence of vitrification during cure eliminates the one-to-one relationship because of the nonequilibrium nature of the glass transition region and of the glassy state. In the glass transition region there is competition between physical aging which increases the density and chemical aging which, after gelation, decreases ρ_RT. After gelation, prolonged isothermal cure and physical aging to well beyond vitrification result in limiting values of ρ_RT which decrease with increasing temperature of cure. The maximum in the ρ_RT vs. conversion relationship is discussed in terms of the effects of shrinkage due to cure, the corresponding nonlinear increase in the glass transition temperature with increasing conversion after gelation, and longer relaxation times in the glass transition region with increasing crosslink density. Other factors which affect room temperature density are discussed.     

A method for electrochemical growth of homogeneous nanocrystalline ZnO thin films at room temperature

We report the electrodeposition at room temperature (25 °C), in a potentiostatic mode, of cohesive nanocrystalline ZnO thin films from an oxygenated zinc chloride bath. It is shown that the bath saturation by molecular oxygen precursor is a key parameter to grow the oxide at low temperature. After low O₂ bubbling the solution is not saturated and the surface is more or less passivated by an amorphous Zn(OH)₂ veil-like thin layer. After intense and long molecular oxygen bubbling, the current density rapidly increases after an induction period of about 800 s. At the foot of the current onset, crystallized ZnO seeds appear entrapped in the initial amorphous layer. The film nucleation is a delayed process. The electrode is subsequently covered by a homogeneous ZnO film with structures of several hundreds of nanometers in length composed of nanocrystals with size of about 17 nm. The room-temperature photoluminescence spectrum of the film is dominated by a strong UV emission at 3.25 eV due to the recombination of excitons. The visible emission centered at 2.36 eV, due to deep defects, is less intense than the UV one showing the good structural quality of the ZnO nanocrystallized film. The films have interesting properties to be used as a seed layer for instance.     

不锈钢常温快速酸洗工艺

为去除不锈钢表面厚氧化皮,常用的酸洗工艺使用温度高、酸洗时间长。采用两步法酸洗工艺,可以在常温下快速去除不锈钢表面厚氧化皮,具有酸洗速度快,使用温度低的优点。酸洗液不含硝酸,环境污染小处理后表面洁净、不失光、不褪色、不泛黄。     

Coloration of stainless steel at room temperature by triangular current scan method

Interference films with gold, red, blue or green color have been successfully produced on stainless steel at room temperature by applying the triangular current scan method. The anodic current scan over the transpassive region led to the forced dissolution of the steel, and the cathodic current on the reverse scan attributed to the reduction of chromate (VI) to Cr³⁺. The metal ions generated by both reactions were hydrolyzed to form an interference film. The thickness (coloration) of the interference film depended linearly on the electrolysis time and the logarithm of the space between the two triangular waves.     

Prediction of creep of nylon-6,6 at constant stress,temperature and moisture content

A method is described of accurately superposing creep curves, obtained at different relative humidities, that each covered six decades of time. The superposition required an empirical distortion of the logarithmic-time scale; for which the justification was that it not only gave more accurate superposition, but also that the same distortion could be successfully used for five relative humidities and three stresses and needed the same horizontal shift factor for all stresses except at the highest relative humidity, of 90%. Equations were fitted to the resulting master curves and non-linearity correction factors, enabling the computer to predict creep curves at any constant stress up to 12 MN/m² and at any constant humidity up to 90% r.h. No attempt has been made to explain the success of the distortion used, but its usefulness is readily apparent.     

The effect of strain rate on the deformation and relaxation behavior of 6/6 nylon at room temperature

The influence of strain rate changes in the range from 10^?3 to 10^?6 1/s on the zero-to-tension loading and unloading behavior as well as short term relaxation properties is investigated using cylindrical specimens of circular cross section. A clip-on extensometer measures and controls the axial strain in an MTS servohydraulic, computer-controlled mechanical testing machine. Strains do not exceed twenty percent and all deformation is macroscopically homogeneous. An increase in strain rate causes an increase in stress level. Surprisingly, the total stress drop in a 20 min relaxation period increases with prior strain rate. When the relaxation test is started in the inelastic region with low tangent modulus the total stress drop is nearly independent of the stress and strain at which relaxation commences. Unloading to zero load is not linear but curved and the strain recovery at zero stress is significant. It occurs at an ever decreasing rate and does not exceed three percent in a 12 h period. Like the relaxation behavior the recovery rate increases with prior strain rate. Repeated relaxation periods during zero-to-tension cycling can show a stress magnitude decrease during loading but a stress magnitude increase during unloading. The results suggest that a unified model with an overstress dependence of the inelastic rate of deformation could be useful in modeling.     

Covalent cross-linking of polymers at room temperature

Thermoplastic materials used in coatings, paints and adhesives as well as structural applications for sensitive substrates, such as wood, paper or polymers, often lack the required chemical and environmental resistance for many applications, which can be overcome by covalent cross-linking. Covalent cross-linking improves chemical and mechanical properties of the material and has been used for many different materials and applications. Room temperature cross-linking can be initiated by different mechanisms and eliminates energy intensive heating as well as conditions potentially harmful for the substrate. The present article focuses on cross-linking strategies applied for different materials, such as thermoplastics and thermosets. It is organized by material class, followed by an overview about triggering mechanisms for cross-linking reactions at room temperature. The authors hope to provide helpful insights about the methods for covalent cross-linking already published.     

室温固化高性能胶粘剂的研制

为了改善环氧树脂(EP)胶粘剂对某些金属和非金属材料的粘接性能,采用自制的增韧剂改性EP,制备了一种可室温固化的无溶剂双组分EP胶粘剂。考察了增韧剂用量、不同的室温固化剂及表面处理方法对金属和非金属材料的粘接性能、耐热性能和耐介质性能的影响。实验结果表明,该胶粘剂对金属和非金属都具有良好的粘接性能;用于PVC和ABS粘接时,则被粘材料被破坏;用于聚四氟乙烯(PTFE)和聚乙烯(PE)粘接时,其最高剪切强度分别为1.9 MPa和1.8 MPa。     

Prediction of stress relaxation during high-speed stretching of synthetic thread

The viscoelastic characteristics obtained with a “family≓ of stress relaxation curves can be used to predict distortion of the stress-strain diagram in going to high deformation rates. Translated from Khimicheskie Volokna, No. 1, pp. 41–43, January–February, 1998.