线状聚羧酸高效减水剂在陶瓷坯料颗粒表面的吸附行为

采用静态吸附实验,研究了陶瓷坯料吸附两种自制聚羧酸高效减水剂的动力学规律,用准二级动力学模型对其吸附过程进行拟合,并通过测定添加了两种自制不同分子结构聚羧酸高效减水剂的陶瓷坯体料浆黏度以评价其分散性能,结果显示,在陶瓷坯体料浆中,线状MA/AA/AMPS聚羧酸高效减水剂的平衡吸附量是梳状AMPS改性聚丙烯酸高效减水剂的2倍以上,陶瓷坯料颗粒表面对两种聚羧酸高效减水剂的吸附均符合准二级反应动力学模型;线状MA/AA/AMPS聚羧酸高效减水剂的分散效能明显好于梳状AMPS改性聚丙烯酸高效减水剂。     

线状聚羧酸减水剂在陶瓷坯料颗粒表面的吸附行为

采用静态吸附实验,研究了陶瓷坯料吸附两种自制聚羧酸高效减水剂的动力学规律,用准二级动力学模型对其吸附过程进行拟合,并通过测定添加了两种自制不同分子结构聚羧酸高效减水剂的陶瓷坯体料浆黏度以评价其分散性能,结果显示,在陶瓷坯体料浆中,线状MA/AA/AMPS聚羧酸高效减水剂的平衡吸附量是梳状AMPS改性聚丙烯酸高效减水剂的2倍以上,陶瓷坯料颗粒表面对两种聚羧酸高效减水剂的吸附均符合准二级反应动力学模型;线状MA/AA/AMPS聚羧酸高效减水剂的分散效能明显好于梳状AMPS改性聚丙烯酸高效减水剂。     

聚羧酸高效陶瓷减水剂的合成及性能

以马来酸酐(MA)、丙烯酸(AA)和2-丙烯酰胺基-2-甲基丙磺酸(AMPS)为单体,采用水溶液聚合法制备了一种线型MA/AA/AMPS聚羧酸高效陶瓷减水剂。通过正交实验,研究了各反应条件对添加了0.35%(相对于绝干料浆质量)线型MA/AA/AMPS聚羧酸高效陶瓷减水剂的陶瓷坯体料浆流动时间的影响,并进一步利用FTIR和XRD等手段对线型MA/AA/AMPS聚羧酸高效陶瓷减水剂的官能团结构和晶相结构进行了表征,分别用POM和SEM照片观察陶瓷坯体料浆的分散情况和陶瓷坯体试样的断面形貌。结果表明,线型MA/AA/AMPS聚羧酸高效陶瓷减水剂最佳合成条件为:聚合温度为80℃、引发剂用量占聚合单体总质量的9%、n(MA)∶n(AA)∶n(AMPS)=1.0∶3.5∶1.5、聚合时间为4 h。当线型MA/AA/AMPS聚羧酸高效陶瓷减水剂掺量为0.35%(相对于绝干料浆质量)时,陶瓷坯体料浆体系的黏度从689.5 mPa·s降低到56.8 mPa·s。     

基于正交试验设计的聚羧酸高效陶瓷减水剂性能

以马来酸酐(MA)、丙烯酸(AA)和2-丙烯酰胺基-2-甲基丙磺酸(AMPS)为单体,采用水溶液聚合法制备了一种线型MA/AA/AMPS聚羧酸高效陶瓷减水剂。通过正交试验,研究了各反应条件对添加了0.35%(相对绝干料浆)线型MA/AA/AMPS聚羧酸高效陶瓷减水剂的陶瓷坯体料浆流动时间的影响,并进一步利用FT-IR和XRD等手段分别对线型MA/AA/AMPS聚羧酸高效陶瓷减水剂的官能团结构和晶相结构进行表征,分别用POM和SEM照片观察陶瓷坯体料浆的分散情况和陶瓷坯体试样的断面形貌。结果表明,线型MA/AA/AMPS聚羧酸高效陶瓷减水剂最佳合成条件为：聚合温度为80 ℃、引发剂用量占聚合单体总质量的9%、n(MA)∶n(AA)∶n(AMPS)=1.0∶3.5∶1.5和聚合时间为4 h。当线型MA/AA/AMPS聚羧酸高效陶瓷减水剂掺量为0.35%(相对绝干料浆)时,陶瓷坯体料浆体系的黏度从689.5 mPa穝降低到56.8 mPa穝。     

线状MA-AA-MAS聚羧酸陶瓷分散剂的制备工艺及其性能

采用水溶液聚合法,以异丁烯磺酸钠(MAS)、丙烯酸(AA)和顺酐(MA)为主要合成原料,合成了一种线状MA-AA-MAS聚羧酸陶瓷分散剂.采用FT-IR手段对其官能团结构进行了表征.分别通过正交和单因素试验以确定各单体比例和研究各单体用量及聚合反应条件对陶瓷坯体料浆流动性能的影响.结果表明,合成该分散剂的最佳工艺条件为:n(MAS)∶n(AA)∶n(MA) =1.0∶3.0∶1.0、w(APS)=8％、聚合温度和时间分别为90℃和5h.当分散剂的掺量为0.35％(相对绝干料浆质量)时,料浆体系的黏度仅为78.2 mPa·s.     

KPS-NaHSO3体系梳型聚羧酸系陶瓷分散剂的合成及性能研究

以羟基纤维素(HEC)、丙烯酸(AA)、甲基丙烯磺酸钠(SMAS)为单体,采用水溶液自由基聚合的方法制备了一种梳型阴离子型陶瓷分散剂.通过试验,研究了各反应条件对添加了0.3％(相对于绝干料浆质量)梳型HEC/AA/SMAS聚羧酸系高效陶瓷分散剂的陶瓷坯体料浆流动时间和厚化度的影响.结果表明,梳型HEC/AA/SMAS聚羧酸高效陶瓷分散剂最佳合成条件为:HEC的用量为0.05 g,NaHSO3的用量为0.45 g,聚合温度为80℃,聚合时间为2h.当梳型HEC/AA/SMAS聚羧酸系高效陶瓷分散剂掺量为0.3％(相对于绝干料浆质量)时,陶瓷坯体料浆体系的流出时间降至36.3 s,厚化度降至10.05.     

光固化ZrO2陶瓷料浆的流变性能研究

围绕陶瓷粉体在光敏树脂中的分散,研究了粉体性质、分散剂种类及其掺加量、固含量对光固化ZrO₂陶瓷料浆流变性能的影响。结果表明:粉体性质对料浆的流变性能有着显著影响,比表面积小、球形度高的ZrO₂陶瓷粉体更有利于配制低粘度、高固含量的料浆;料浆的流变性能以及稳定性主要受分散剂种类及其掺加量的控制,以相对粉体质量4%的X-100分散剂制备的陶瓷料浆的流变性及稳定性更佳;固含量与粘度之间的关系满足Krieger-Dougherty模型。本文对分散剂的作用机理进行了分析探讨,为光固化ZrO₂陶瓷料浆高精度固化成型提供了试验基础。     

超分散剂的合成及其对墙地砖浆料流变性、坯体强度的研究

以2-丙烯酰胺-2-甲基丙磺酸、衣康酸、丙烯酸、烯丙基聚醚等合成了一系列四元聚羧酸/磺酸型梳状超分散剂(SKD系列).研究了超分散剂的结构、组成、pH值、添加量等对墙地砖料浆分散性能和坯体强度的影响.结果表明,超分散剂具有梳形分子结构,其性能受羧基中和程度、官能团密度和侧链长度影响,当其pH=8,侧链长度为20,添加量为0.20%时,使浆料粘度从3235mPa·s到40mPa·s,使坯体强度增加1 23.87%.     

全废瓷料原位凝固成型制备建筑陶瓷的研究

通过瓜尔豆胶原位凝固成型技术制备建筑陶瓷,分别以废瓷粉、瓜尔豆胶和聚羧酸为原料,经原位凝固成型工艺制得陶瓷坯体,通过高温烧结制备建筑陶瓷样品。研究了瓜尔豆胶添加量对浆料流变性能的影响,并对瓜尔豆胶添加量对生坯和烧结性能影响进行分析。结果表明:通过添加0.35~0.55 wt%瓜尔豆胶可实现全废瓷料原位凝固成型,并可以制备具有高强度、低收缩率的瓷质建筑陶瓷烧结样品。     

陶瓷添加剂对Al_2O_3陶瓷成形工艺的影响研究

陶瓷添加剂是陶瓷制备过程中添加的用以改善陶瓷浆料,坯体等性能的无机或有机精细化工原料。在氧化铝陶瓷浆料制备中,为获取更好流动性的浆体,往往添加一定数量的表面活性剂加以改善;为增强氧化铝成形坯体的强度,可通过添加一定的粘合剂进行改善。本文通过分散剂的基团分析,探究了分散剂分散机理,并研究了分散剂加入对氧化铝坯体致密度的影响;通过对改性淀粉的加热粘度分析,探究了改性淀粉在氧化铝陶瓷制备中的重要应用原理;通过添加消泡剂对气孔率影响的分析,使坯体气孔率有较显著改善。     

EVA/EPDM/IR/IR共混发泡材料的性能研究

研究了乙烯醋酸乙烯酯共聚物（ＥＶＡ）／ＥＰＤＭ／ＩＲ三元共混和ＥＶＡ／ＥＰＤＭ／ＩＲ／ＩＲ四元共混发泡材料的性能。在ＥＶＡ中混入ＥＰＤＭ可使发泡材料的拉伸强度、撕裂强度和粘合强度提高,而收缩率和压缩永久变形降低;在ＥＶＡ中混入ＩＲ除具备混入ＥＰＤＭ同样的优点外,还可提高发泡材料的柔性;ＩＲ的混入可改善发泡材料二次热压成型制品的表面清晰度。     

Effect of V2O5 Doping on the Sintering and Dielectric Properties of M-Phase Li1+x−yNb1−x−3yTix+4yO3 Ceramics

The effect of the addition of V₂O₅ on the structure, sintering and dielectric properties of M -phase (Li_{1+ x − y} Nb_{1− x −3 y} Ti _x +4 _y )O₃ ceramics has been investigated. Homogeneous substitution of V⁵⁺ for Nb⁵⁺ was obtained in LiNb_{0.6(1− x )}V_{0.6 x} Ti_0.5O₃ for x ≤ 0.02. The addition of V₂O₅ led to a large reduction in the sintering temperature and samples with x = 0.02 could be fully densified at 900°C. The substitution of vanadia had a relatively minor adverse effect on the microwave dielectric properties of the M -phase system and the x = 0.02 ceramics had [alt epsilon]_r= 66, Q × f = 3800 at 5.6 GHz, and τ_f= 11 ppm/°C. Preliminary investigations suggest that silver metallization does not diffuse into the V₂O₅-doped M -phase ceramics at 900°C, making these materials potential candidates for low-temperature cofired ceramic (LTCC) applications.     

聚烯烃塑料用胶粘剂SBS／MMA／BA／MAA的合成与性能研究

以甲基丙烯酸（MAA）为功能单体,与SBS和甲基丙烯酸甲酯（MMA）、丙烯酸丁酯（BA）进行四元接枝共聚,合成了聚烯烃塑料用胶粘剂,探讨了不同溶剂、MMA／BA配比、MAA和BPO用量以及固化时间对粘接性能的影响,并对该四元接枝胶的性能与三元胶和SBS／MMA／BA／AA四元接枝胶进行了比较。结果发现：四元接枝胶性能优于三元胶,特别是与异氰酸酯配合时,剪切强度、固化速度明显提高,四元胶的优化配方是120＃汽油：甲苯：乙酸乙酯为8：1：1,MMA：BA配比3：1,MAA加入量7份,BPO用量1．5－2份（以100份SBS计）。     

BA／VAc／AN／AA共聚乳液胶粘剂的研制

介绍了一种丙烯酸丁酯／醋酸乙烯酯／丙烯腈／丙烯酸四元共聚乳液胶粘剂的制备方法,该胶具有良好的耐黄变性,可替代天然橡胶胶乳应用于EVA低发泡体与腈纶绒面布的复合。     

Microwave Dielectric Properties of CaTiO3-CaAl1/2Nb1/2O3 Ceramics Doped with Li3NbO4

The microwave dielectric properties of CaTi_{1− x} (Al_1/2Nb_1/2) _x O₃ solid solutions (0.3 ≤ x ≤ 0.7) have been investigated. The sintered samples had perovskite structures similar to CaTiO₃. The substitution of Ti⁴⁺ by Al³⁺/Nb⁵⁺ improved the quality factor Q of the sintered specimens. A small addition of Li₃NbO₄ (about 1 wt%) was found to be very effective for lowering sintering temperature of ceramics from 1450–1500° to 1300°C. The composition with x = 0.5 sintered at 1300°C for 5 h revealed excellent dielectric properties, namely, a dielectric constant (ɛ_r) of 48, a Q × f value of 32 100 GHz, and a temperature coefficient of the resonant frequency (τ_f) of −2 ppm/K. Li₃NbO₄ as a sintering additive had no harmful influence on τ_f of ceramics.     

EVA/EPDM/IR/IR共混发泡材料的研制与应用

进行了ＥＶＡ／ＥＰＤＭ／ＩＲ三元共混和ＥＶＡ／ＥＰＤＭ／ＩＲ／ＩＲ四元共混发泡材料的研制,经物性对比表明：共混发泡材料的物性较非共混发泡普遍提高。ＥＰＤＭ的混入可以增加发泡材料的拉伸强度和撕裂强度,同时降低收缩率和永久压缩变形;ＩＲ的混入除具备ＥＰＤＭ的优点外尚对提高发泡材料的柔软度有帮助;ＩＲ的混入仅改善发泡材料二次热压成型制品表面的清晰度。     

Effect of Nb2O5/ZnO Addition on Microwave Properties of (Zr0.8Sn0.2)TiO4 Ceramics

The effects of Nb₂O₅ and ZnO addition on the dielectric properties, especially the quality factor, of (Zr_0.8Sn_0.2)TiO₄ (ZST) ceramics were investigated in terms of the sintered density acquired by the zinc. For ZST ceramics with 2 mol% added ZnO, the relative density of the samples decreased with >0.5 mol% addition of Nb₂O₅. On the other hand, for samples with 6 mol% added ZnO, the relative density remained >97%, even when the amount of Nb₂O₅ was increased to 2.0 mol%. When >0.5 mol% Nb₂O₅ was added, both the quality factor and the dielectric constant exhibited similar trends with sintered density. The ZST ceramics with 6 mol% added ZnO, especially, still manifested a quality factor >40 000 and a dielectric constant of 37, even when the amount of Nb₂O₅ was increased, values that are not explainable by the previously suggested electronic defect model.     

SO42-/MxOy型固体超强酸研究进展

SO₄^2-/M_xO_y固体超强酸具有不腐蚀设备、污染小、耐高温、对水稳定性好和可重复使用等优点。综述了SO₄^2-/M_xO_y型固体超强酸的催化机理、失活原因、改性及表征方法,并对今后SO₄^2-/M_xO_y型固体超强酸的研究方向进行了展望。     

Ferromagnetism and Magnetoresistance in La0.67Sr0.33Fe0.07Mn0.93O3

A bulk ceramic sample La_0.67Sr_0.33Fe_0.07Mn_0.93O₃ (LSFMO) with a rhombohedral structure has been prepared from a coprecipitated carbonate precursor in this study. Ferromagnetism and a negative, isotropic magnetoresistance (MR) as large as 11% have been observed in a ceramic sample of LSFMO. There are two resistivity transition peaks on the resistivity versus temperature curves. The resistivity peak and MR have been related to the ferromagnetic state in LSFMO.     

Relaxor Behavior of the 0.9BaTiO3–0.1La(Mg1/2Ti1/2)O3 Solid Solution

Low-frequency dielectric response of air- and oxygen-sintered ceramics with the composition 0.9BaTiO₃–0.1La(Mg_1/2Ti_1/2) O₃ (0.9BT–0.1LMT) has been studied in the temperature range of 12–550 K. In comparison with pure BT, in 0.9BT–0.1LMT the dielectric permittivity maximum is shifted by almost 300 K toward lower temperatures. Both real and imaginary parts of dielectric permittivity of the solid solution, in the range 12–150 K, show a strong frequency-dependent behavior, which is typical of relaxors. On the basis of the model of exponential cluster size distribution and the Cole–Cole equation, the degree of interaction between the polar clusters was estimated. It was shown that the oxygen vacancies arising during sintering at high temperatures did not affect noticeably the relaxor properties of the material. The role of heterovalent La³⁺/Ba²⁺ and Mg²⁺/Ti⁴⁺ substitutions in the relaxor behavior formation is discussed.