PS-b-PAA嵌段共聚物包覆碳酸钙的表界面性质和机理研究

通过聚苯乙烯-丙烯酸嵌段共聚物(PS-b-PAA)包覆碳酸钙系列样品的溶解曲线，结合近红外光谱和XPS推断得到了PS-b-PAA分子与碳酸钙表面的键合方式、形态和作用机理。认为形成单分子层包覆时表面PS-b-PAA的质量分数(Cb)为0．92％。PS-b-PAA羧基与碳酸钙表面的作用方式为：CaCO3 [-C-CCOO^--]n→Ca[-OOCC-C-]n CO3^2-。在PS-b-PAA浓度较低时。热力学上的不稳定使得链呈现PAA朝下的竖直状态，而随着PS-b-PAA浓度的增加，PS链段岛状聚集体的形成。原先直立和新键合的PS-b-PAA链将逐渐地以包绕的方式结合在碳酸钙的表面。     

聚对苯二甲酸乙二醇酯/碳酸钙纳米复合材料的制备和表征

以聚乙二醇磷酸酯1000为表面处理剂, 采用碳化法合成了方解石型碳酸钙纳米粒子, 进一步制备了聚对苯二甲酸乙二醇酯/碳酸钙纳米复合材料. 采用透射电子显微镜(TEM)、 X射线衍射(XRD)、 傅里叶变换红外光谱(FTIR), 场发射扫描电子显微镜(FESEM)和热重分析(TGA)对样品进行了分析. 结果表明, 聚乙二醇磷酸酯1000成功地修饰到碳酸钙的表面, 并得到平均直径为60 nm, 形貌为立方体的纳米碳酸钙晶体. 与碳酸钙(空白)样品相比, 表面处理碳酸钙的复合材料表现出更好的分散性和热稳定性. 采用Friedman方法计算了复合材料热分解的活化能. 聚对苯二甲酸乙二醇酯、 聚对苯二甲酸乙二醇酯/空白碳酸钙和聚对苯二甲酸乙二醇酯/表面处理碳酸钙的活化能分别为200.58, 214.86和219.50 kJ/mol, 进一步说明了表面处理碳酸钙更好地改善了聚对苯二甲酸乙二醇酯的热稳定性.     

SiO2包覆超细CaCO3的微晶分析和XPS研究

超细碳酸钙在橡胶、塑料、造纸、涂料、油墨、医药、化妆品等工业中有广泛应用,碳酸钙粉末表面具有许多水羟基,表面是亲水疏油性的,易形成聚集体,分散性能差,直接应用效果不好。因此,根据其本身的笥质及其应用目的,对其进行表面处理,以相应提高其应用性能,碳酸钙的表面处理是通过物理或化学方法将表面处理剂吸附或反应在碳酸钙的表面,形成表面改性层,使其表面活性化,以改善碳酸钙的表面性能,目前碳酸钙的表面改性大多为有机表面改性,偶连有主性,高分子（聚合物）表面改性等^[1],而无碳酸钙的表面改性大多为有机表面改性,偶连剂表面改性,高分子（聚合物）表面改性等^[1],而无机表面改性却很少报道,我们通过研究在碳酸钙表面成功的包覆了无机ＳiO2层,提高了其表面光滑度、白度、耐酸性等性质,能大大改善在造纸,食品、牙膏、涂料等行业中的应用性,并且在一定程度上具有纳米ＳiO2 的特性,可用来代替较为昂贵的纳米ＳiO(白碳黑）,有较好的经济效益,本文对ＳiO2包覆的超细ＣaCO3（以下表示为ＳiO2/CaCO3)做了Ｘ射线粉晶衍射（ＸＲＤ）、Ｘ射线光电子能谱（ＸＰＳ）等研究,并得出了相应的结论。     

SiO_2包覆超细CaCO_3的微晶分析和XPS研究

0引 言 超细碳酸钙在橡胶、塑料、造纸、涂料、油墨、医药、化妆品等工业中有广泛应用。碳酸钙粉末表面具有许多水羟基,表面是亲水疏油性的 ,易形成聚集体 ,分散性能差 ,直接应用效果不好。因此,根据其本身的性质及其应用目的,对其进行表面处理,以相应提高其应用性能。碳酸钙的表面处理是通过物理或化学方法将表面处理剂吸附或反应在碳酸钙的表面,形成表面改性层,使其表面活性化,以改善碳酸钙的表面性能。目前碳酸钙的表面改性大多为有机表面改性、偶连剂表面改性、高分子（聚合物）表面改性等 [1],而无机表面改性却很少有报道。我…     

界面对聚丙烯/碳酸钙复合材料光氧老化的影响

以聚丙烯(PP)/碳酸钙为研究对象,以复合材料界面为着眼点,探讨了不同的填料粒径和表面组成对复合材料光氧老化的影响,并提出了相关机理.首先,文中认为聚合物/无机填料界面面积与界面化学组成是影响老化速率的关键因素.聚合物与碳酸钙的总界面面积的增大会加速PP的光氧老化,不同偶联剂处理会改变碳酸钙的表面化学特性进而对PP老化产生促进或抑制.在此基础上提出了基于界面的老化反应速率概念及相应模型.其次,在老化领域采用了"界面放大"的实验方案,验证了碳酸钙对PP的老化促进很大程度上来源于碳酸钙表面的化学组成.此外,研究发现采用表面处理剂钛酸酯改性的碳酸钙能大大促进PP的老化,且表现为钛酸酯与碳酸钙的协同效果.     

类珍珠质结构的再生丝素蛋白/文石复合材料的仿生制备

详细研究了不同浓度的聚丙烯酸(分子量为2000, PAA-2k)和镁离子对碳酸钙在再生丝素蛋白(RSF)膜表面结晶的影响. 发现单独采用PAA-2k时, 碳酸钙主要以方解石形式在RSF膜表面沉积成膜; 若加入一定量的镁离子参与共同调控, 碳酸钙则有可能在RSF膜表面形成以文石为主的连续薄膜, 进而得到了具有类珍珠质结构的层状RSF/文石复合材料. 我们认为, 吸附在RSF膜表面的PAA对碳酸钙成核诱导作用及其溶液中PAA对碳酸钙结晶抑制作用共同导致RSF膜表面碳酸钙薄膜的形成.     

化学力显微镜对ω-巯基正十一胺自组装单分子膜的力滴定研究

采用化学力显微术（ＣＦＭ）研究了一种长链氨基自组装单分子膜的力滴定性质,考察了表面基团性质不同的力探针对力滴定的影响,滴定了金包覆的Ｓｉ３Ｎ经－ＯＨ和－ＮＨ２基功能化的金样品之间的粘滞力,得到了作为淀粉 ＰＨ值函数的粘滞力曲线（力滴定曲线）,结果表明,－ＮＨ２和－ＯＨ基功能化的表面ｐＫ１／２分别为８．４和９．０。     

火焰原子吸收法测定胶乳中的铁

用硝酸消解胶乳样品，以氨水溶解消解产物，加入磺基水杨酸与铁形成 三磺基水杨酸铁配合物，以工作曲线法测定。建立了在氨性溶液中快速测定胶乳中铁的FAAS法。对样品处理方法、消解产物的溶解性质、磺基水杨酸铁配合物的稳定性、试液和空白溶液粘度一致性、线性范围及检出限进行了考察。测定结果的相对标准偏差为5．6％，加标回收率95．0％－99．5％。     

CaCO_3表面包覆改性及其对填充PP力学性能的影响

先用丙烯酸(AA)处理CaCO3,在其表面引入活性双键基团后,再通过固相包覆反应将聚丙烯蜡(PPW)固定在CaCO3表面.实验发现改性CaCO3可经受甲苯、稀盐酸处理而不发生溶解,结合红外及热重分析结果,证明PPW已经通过化学键合而成功地包覆在CaCO3表面.将该改性CaCO3填充聚丙烯(PP)后,发现PP的冲击性能及拉伸性能均有不同程度的提高,当改性CaCO3的填充量为15份时,体系的缺口冲击强度达到最大值,为基体树脂的1.68倍;当改性CaCO3的填充量10份时拉伸强度达到峰值,为同等添加量的未改性CaCO3的1.22倍.     

纳米碳酸钙及其表面处理对等规聚丙烯结晶行为的影响

应用差示扫描量热方法研究了不同表面改性碳酸钙纳米粒子对聚丙烯 (PP)等温与非等温结晶动力学的影响 ,并研究了上述各聚丙烯结晶样品的熔融行为和晶型 .研究发现纳米碳酸钙具有明显的成核效应 ,并具有较强的诱导 β 型结晶的能力 ,而且与粒子的表面处理密切相关 .     

Surface modification of calcium hydroxyapatite with pyrophosphoric acid

The surface of synthetic colloidal calcium hydroxyapatite (Ca(10)(PO(4))(6)(OH)(2); CaHap) was treated with pyrophosphoric acid (H(4)P(2)O(7); PP) in acetone and the materials were characterized by XRD, thermal analysis, N(2) adsorption, TEM, and FTIR. No remarkable change in XRD patterns or in particle morphology by the modification was observed. The additional amount of PO(4) of CaHap was increased with an increase in PP concentration. The Ca/P molar ratio of CaHap was decreased from 1.62 to 1.35 by the modification. IR results indicated that the PP reacts with surface P-OH groups of CaHap to form additional surface P-OH groups as follows: surface P-OH+H(4)P(2)O(7)--> surface P-O-PO(OH)(2) + H(3)PO(4). When the modified CaHap with Ca/P molar ratio less than 1.50 was treated at 850 degrees C in air, the materials transformed into beta-Ca(3)(PO(4))(2).     

Formation of Hydrophobic Silica Coatings on Stones for Conservation of Historic Sculptures

The conservation of historic sculptures is receiving growing attention because of the increasing air pollution. A hydrophobic silica coating was synthesized to protect historic sculptures from weathering by starting from a solution of tetraethoxyorthosilicate (TEOS) precursor using hexadecyltrimethoxysilane (HDTMS) as hydrophobic modifier in the presence of ammonia as a catalyst. The molar ratio of ethanol, TEOS, H₂O and NH₄OH was kept constant at 8:0.045:3:2.8 and the molar ratio of HDTMS/TEOS (M) was varied from 0 to 0.458. The organic modification was confirmed by infrared spectroscopic studies, and the hydrophobicity of the coating was tested by the contact angle measurements. The stone surface morphology of sample treated with silica coating was characterized. The results showed that the nanocomposites were composed of spherical particles with grain size of about 190 nm in diameter. After the limestone's surface was modified, the contact angle of limestone increased from 20° to 100° for M0.458. The protective performance evaluated with its ability to resist acid rain reveals that the protective effects are satisfying.     

Kinetic isotope effects on the dissolution kinetics of solid salicylic acid in aqueous solution: evidence for solubilisation via a proton dissociation-recombination mechanism

Quantitative Atomic Force Microscopy measurements made on the dissolving surface of solid salicylic acid in H2O and D2O reveal a kinetic isotope effect (kH/kD = 2.3 +/- 0.6) on the dissolution rate consistent with a transition state in which the proton is dissociated from the dissolving molecule.     

Preparation and characterization of organic–inorganic hybrids and coating films from 3‐methacryloxypropylpolysilsesquioxane

3‐Methacryloxypropylpolysilsesquioxane (MA‐PS) was prepared by acid‐ or base‐catalyzed hydrolytic polycondensation of 3‐methacryloxypropyltrimethoxysilane (MAS). MA‐PS coating film was prepared by dip‐coating on organic, metal and inorganic substrates, including poly(ethylene terephthalate), aluminum, stainless steel, and glass. The coating films on poly(ethylene terephthalate) and glass showed high adhesive strength. The hardness of coating films increased with increasing heat treatment temperature, whereas they decreased with increasing H₂O/MAS molar ratio. The refractive index of coating films increased with increasing heat treatment temperature. In addition, flat and transparent free‐standing films (0.24–0.27 mm thickness) were prepared from MA‐PS that were crack‐free after heat treatment at 1000 °C. Copyright © 2001 John Wiley & Sons, Ltd.     

液相法合成锂离子电池正极材料Li_(1+x)Mn_2O_4

采用柠檬酸络合和溶液浸渍两种方法制备Li1+xMn2 O4正极材料 ,用XRD和BET测试了材料晶体结构和比表面积 ,考察焙烧温度、Li/Mn比、起始原料对产物结构和电化学性能的影响 ,结果表明 ,焙烧温度与Li/Mn比是影响材料电化学性能的关键因素 ,确定了制备Li1+xMn2 O4材料最佳条件为 0≤x≤ 0 .0 5 ,焙烧温度 75 0°C ,所得电池材料首次充放电容量达到 1 2 0mAh/g .循环 5 0次后 ,其充放电容量为 1 1 5mAh/g .     

Structure of synthetic calcium hydroxyapatite particles modified with pyrophosphoric acid

Synthetic colloidal calcium hydroxyapatite (Ca(10)(PO(4))(6)(OH)(2): CaHap) was treated with pyrophosphoric acid (H(4)P(2)O(7): PP) in acetone and the materials were characterized by XRD, TEM, FTIR, and N(2) and H(2)O adsorption measurements. XRD patterns and morphology of CaHap particles were essentially not changed by the modification. The additional amount of PO(4) of CaHap was increased with an increase of PP concentration and the Ca/P molar ratio of the particles decreased from 1.62 to 0.81. IR results indicated that the isolated surface POH band developed with increasing the PP concentration up to 6.0 mmol dm(-3) by the reaction of isolated surface POH groups of CaHap and pyrophosphoric acids. Above 10.2 mmol dm(-3), a hydrogen-bonding surface POH band appeared at 2913 cm(-1) and enlarged with increasing the PP concentration, while the isolated surface POH band was weakened. The results of N(2) and H(2)O adsorption measurements revealed that the modified particles aggregated compared to the unmodified ones, which would be due to the formation of hydrogen-bonding surface POH groups among the particles.     

低硅铝比ZSM-5分子筛上C4烃的催化裂解反应

以低硅铝比(n(SiO2)/n(Al2O3)=20-45)的ZSM-5分子筛为催化剂, 研究了混合C4烃的催化裂解反应, 并对不同硅铝比的ZSM-5分子筛进行了酸性表征. 混合C4烃的催化裂解反应结果表明, 低硅铝比的ZSM-5分子筛具有较高的低温催化活性, 高硅铝比ZSM-5分子筛催化剂上乙烯和丙烯的收率高于低硅铝比ZSM-5分子筛催化剂, 低硅铝比ZSM-5分子筛上苯和甲苯的收率高于高硅铝比ZSM-5分子筛催化剂. 在反应温度为625 ℃时, 硅铝比为20的ZSM-5分子筛催化剂上乙烯、丙烯、苯和甲苯的总收率可达79.42%. 酸性表征结果表明, 硅铝比低的ZSM-5分子筛具有更多的Bronsted(B)酸酸量、Lewis(L)酸酸量及总酸酸量, 这是低硅铝比ZSM-5分子筛具有低温高活性及高的苯和甲苯收率的原因.     

Effects of ammonium exchange and Si/Al ratio on the conversion of methanol to propylene over a novel and large partical size ZSM-5

One type of ZSM-5 zeolite with large partical size was prepared and characterized by XRD, SEM, N2 adsorption-desorption, XRF, Py-IR and NH3-TPD techniques. Effects of ammonium exchange and SiO2/Al2O3 molar ratios on the reaction of methanol to propylene (MTP) over Na-ZSM-5 and H-ZSM-5 zeolites have been studied in a fixed-bed flow reactor under the operating conditions of T = 500 °C, P = 1 atm, and WHSV = 6 h-1. Ammonium exchange led to a rapid decrease in Na content for Na-ZSM-5 zeolite. The reaction results indicated that Na-ZSM-5 and H-ZSM-5 with different SiO2/Al2O3 molar ratios all exhibited high activity for methanol conversion. Ammonium exchange and the decreased SiO2/Al2O3 molar ratio of ZSM-5 zeolite led to an increase both in strong acid sites and weak acid sites. Na-ZSM-5 with high SiO2/Al2O3 molar ratio was favorable for the formation of propylene. The highest propylene selectivity (45.9%) was obtained over Na-ZSM-5 zeolite catalyst with SiO2/Al2O3 molar ratio of 220.     

电化学法制备生物活性陶瓷材料研究

利用电化学方法可以在温和条件下制备生物活性陶瓷涂覆层，从而避免了高温喷涂引起的相变和脆裂，并可在形状复杂的基底上得到均匀的沉积层．因此，近年来在金属表面电沉积生物活性陶瓷涂覆层的研究方面已引起高度重视［’－‘j，然而，目前大多数文献报道所采用的恒电位方法，在沉积过程中电极表面的喊度会发生较大的变化，难以得到组分均匀的沉积层．本文报道用恒电流模式在Ti－6A14V合金表面沉积羟基磷灰石生物陶瓷涂层．1实验部分Ti－6A14V合金为电沉积基底（直径为0．65cm），辅助电极为Pt电极，参比电极采用饱和甘汞电极（SCE）．…     

A novel method to synthesize hydroxyapatite coating with hierarchical structure

A novel process has been developed for the preparation of a hydroxyapatite (HA) coating with a hierarchical structure on a Ti substrate. The Ti substrate was first subjected to electrolytic deposition at -1.6V (versus Ag/AgCl/KCl) in a solution of 0.042M Ca(NO(3))(2)·4H(2)O and 0.025M NH(4)H(2)PO(4) at 85°C for 3min, and then post-treated in a 0.25M NaOH solution, with the addition of 0.05M Na(3)Cit at 85°C for 5h. The experimental results showed that the coating experienced a phase conversion from octacalcium phosphate to HA after the post-treatment step. The HA coating had well-distributed, micro-sized pores comprising three-dimensional interconnected mesoporous HA belts, which would greatly increase the porosity and surface area of the coating.