新型苯并环丁烯树脂的合成与性能研究

采用4-溴苯并环丁烯和双酚A合成了一种含芳醚结构的双苯并环丁烯单体,通过DSC测试分析了该单体的固化行为.由该单体经加热固化后得到了一种新型的苯并环丁烯树脂,分析测试了该树脂的热性能、力学性能、电性能和吸水率,结果表明该树脂具有高的耐热稳定性、低的介电常数和吸水率,是一种综合性能优异的热固性树脂.     

Aging effect of pH on the mechanical and tribological properties of dental composite resins

This study evaluated the microhardness and wear behavior alterations of dental resins exposed to strong acid and alkaline degradation regimens. Fifty specimens of AP-X, Z350, P60, VITA ZETA and VITA LC resins were distributed into 10 groups. The control group was not subjected to aging treatment, while the other nine groups were assigned to the following pH solutions: 1, 7 or 13 for 1, 13 or 20 d, respectively. Vickers microhardness and wear behavior of materials without aging served as the reference. Repeated measurements were conducted for other specimens. Scanning electron microscopy was used to observe the morphology. Data were analyzed by repeated-measures one-way ANOVA, followed by the least significant difference (LSD) t-test (P?≤?0.05) for multiple comparisons. The aging process was aggravated over time. Alkaline medium significantly decreased the microhardness and wear resistance of resins, and led to serious surface damage. AP-X, P60 and Z350 immersed in different media showed a lower degradation than the nanoresin. The mechanical degradation of resin composites was aggravated with increased aging time. Strong alkaline media induced the largest reduction in mechanical and tribological properties. Hybrid resin composites with high filler loading exhibited better mechanical performance than nanoresins with low filler loading under different pH conditions.     

碱溶性光敏预聚物的合成与光固化性能研究

以三苯基膦作催化剂,苯酐(PA)与丙烯酸羟乙酯(HEA)反应,合成了碱溶性光敏预聚物(PA-HEA)。通过对反应体系酸值的测定,研究了反应时间、配比、催化剂用量及投料方式对预聚物转化率的影响;通过将光引发剂加入预聚物,经紫外光固化后,考察了固化膜的耐酸性、碱液剥膜、热稳定性等性能。结果表明,在反应时间为3h,HEA与PA配比1∶0.75,催化剂含量1%(质量分数)时,转化率较高;固化膜能在10%盐酸中耐酸30min以上,且在1%NaOH溶液中2min内可完全脱膜,在32.6～137℃有较好的热稳定性。     

有机硅改性丙烯酸树脂乳液的合成及性能研究

采用乳液聚合法,并以种子乳液法分步加料方式,将一定比例丙烯酸酯单体、自制的有机硅大分子单体进行自由基聚合,得到有机硅改性丙烯酸树脂乳液.利用单因素实验和5因素4水平正交实验优化出最佳工艺参数:MM用量为1.2%,有机硅预聚体的用量为9%,单体配比为0.76,异丙醇用量为1.5%,可获得高稳定性乳液,成膜各项性能提高.     

Synthesis and photocuring UV-curable/alkali-soluble properties of acrylic resin

以三苯基膦作催化剂,苯酐（PA）与丙烯酸羟乙酯（HEA）反应,合成了碱溶性光敏预聚物（PA-HEA）。通过对反应体系酸值的测定,研究了反应时间、配比、催化剂用量及投料方式对预聚物转化率的影响;通过将光引发剂加入预聚物,经紫外光固化后,考察了固化膜的耐酸性、碱液剥膜、热稳定性等性能。结果表明,在反应时间为3h,HEA与PA配比1∶0.75,催化剂含量1%（质量分数）时,转化率较高;固化膜能在10%盐酸中耐酸30min以上,且在1%NaOH溶液中2min内可完全脱膜,在32.6～137℃有较好的热稳定性。     

Synthesis of ZnO nanoparticles and study of their antibacterial and antifungal properties

In this paper, ZnO nanoparticles have been synthesized with and without the use of surfactants under different reaction conditions. The size of the ZnO nanoparticles varied in diameter (2 nm-28 nm) according to the reaction conditions employed. Promising particle size dependent antibacterial and antifungal activities of the ZnO nanoparticles have been observed. Transmission electron microscopy (TEM), X-ray diffraction (XRD) and Infrared spectroscopy (FTIR) techniques were used to characterize the particle size and morphology.     

Synthesis and properties of peroxy derivatives of phenol – formaldehyde resins

Methods of obtaining peroxy derivatives of phenol-formaldehyde resins (PhFRs) have been elaborated. Three different procedures have been pursued: i) chemical modification of PhFRs with hydroperoxides; ii) modification of PhFRs with 1.2-epoxy-3-tert-butylperoxypropane; and iii) polycondensation of peroxy phenols with formaldehyde. Structures of the resins were determined by chemical and spectroscopic methods. The results were also used to create three-dimensional networks involving an unsaturated polyester resin. IR-spectroscopy of the networks shows that, in addition to the peroxy groups and unsaturated bonds, others functional groups participate in the network formation. Received: 21 May 1999 / Reviewed and accepted: 20 July 1999     

水分散多异氰酸酯交联苯乙烯-丙烯酸酯树脂的制备及性能

以苯乙烯、丙烯酸丁酯、N-羟甲基丙烯酰胺、丙烯酰胺为原料,用聚乙烯醇(PVA)作为胶体保护剂,采用无皂乳液聚合方式,制备苯乙烯-丙烯酸酯树脂乳液;以HDI三聚体和聚乙二醇单甲醚(MPEG500)为主要原料制备水可分散聚异氰酸酯.苯乙烯-丙烯酸酯树脂乳液与亲水改性聚异氰酸酯复合,得到水分散多异氰酸酯交联改性的苯乙烯-丙烯...     

Synthesis and characterization of a novel dimethacrylate based on adamantane as possible dental resins

In this study a novel dimethacrylate based on adamantine (AB-GMA) was synthesized and proposed as possible dental monomers for dental resin mixtures. The monomer was prepared by the reaction of glycidyl methacrylate with dicarboxylic acid ester obtained from adamantanediol and maleic anhydride. The addition reaction of glycidyl methacrylate and the acidic compound was carried out in the presence of basic catalyst—tetraethylammonium bromide. AB-GMA was copolymerized with TEGDMA by varying the curing conditions: monomer composition, photoinitiator concentration and light intensity. A Real-time FTIR technique was employed to monitor the double bond conversion and the rate of polymerization. The prepared polymers were also subjected to dynamic mechanical studies (DMA). AB-GMA exhibited high degree of double bond conversion (up to 77%) and its thermo-mechanical properties were better than those of the commonly known dimethacrylates. AB-GMA showed no cytotoxicity toward growth of L929 cells and had good in vitro biocompatibility.     

Synthesis and properties of dental zirconia–leucite composites

The dental zirconia–leucite composites were synthesized by high temperature solid-state method using potash feldspar, potassium carbonate and zirconia as raw materials. The mechanical properties and the coefficient of thermal expansion (CTE) of the prepared zirconia–leucite composites were tested. The results show that the bending strength, the fracture toughness and the metal–ceramic bonding strength of the prepared samples are about 110 MPa, 3·5 MPa/m^1/2 and 45 MPa, respectively. The CTE was about 13·73×10^–6 °C^–1 and close to that of Ni–Cr dental alloy (14·0×10^–6 °C^–1). The results indicate that the introduction of zirconia is beneficial to the improvement in the mechanical properties and CTE adjustment of porcelain material. The clinical application of the zirconia–leucite composites with good metal–ceramic bonding strength in the dental restoration could be envisioned.     

Synthesis of some ferromagnetic composite resins and their metal removal characteristics in aqueous solutions

In this study, a procedure for synthesis of new organic-inorganic magnetic composite resins was established. The procedure was based upon immobilization of magnetite (Mag) as a ferromagnetic material within the polymer poly(acrylic acid acrylonitrile) P(AA-AN) and the ion exchange resin (Amberlite IR120). The produced magnetic resins, IR120-PAN-Mag (R1) and P(AA-AN)-Mag (R2) were assessed as sorbents for Cr(VI). Various factors influencing the sorption of Cr(VI), e.g., pH, equilibrium time, initial concentration and temperature were studied. The sorption process was very fast initially and maximum sorption was achieved within 3 h and pH 5.1. The kinetic of the system has been evaluated with pseudo first order model, second order model, Elovich model, intra-particle diffusion model and liquid film diffusion model. Chromium interaction with composite particles followed second-order kinetics with a correlation coefficient extremely high and closer to unity and rate constant (k_s) has the values 1.68 × 10⁻⁴ and 1.9 × 10⁻⁴ g (mg⁻¹ min⁻¹) for R1 and R2, respectively. The values of equilibrium sorption capacity (q_e) are consistent with the modeled data and attain the range 893–951 mg g⁻¹. Kinetically, both pore diffusion and film diffusion are participating in ruling the diffusion of Cr(VI) ions. The sorption data gave good fits with Temkin and Flory–Huggins isotherm models. The isotherm parameters related to the heat of sorption are in the range 8–16 kJ mol⁻¹ which is the range of bonding energy for ion exchange interactions and so suggest an ion exchange mechanism for removal of Cr(VI) by the composite sorbents. The adsorption process was exothermic with ΔH in the range of −73 to −97 kJ mol⁻¹. The negative values of Gibbs free energy confirm the feasibility and the spontaneous nature of Cr(VI) removal with these novel composites.     

Abrasive wear of dental composite resins

Abrasive wear is a major problem in the application of dental composite resins. In this study the friction and wear behaviours of two types of dental composites: one containing relatively coarse filler particles and some microfillers (Estilux) and another containing only microfiller particles (Durafill), have been investigated by using a scratch testing machine. Experimental results show that the coefficients of friction in both composites are essentially constant for applied loads up to 20 N. The wear resistance of Durafill is better than Estilux. Under the same testing conditions, the size, shape and distribution of the filler particles are more important variables than applied load and sliding speed in controlling the wear mechanism. It is shown that for Estilux, plastic ploughing by the diamond indenter is the predominant mechanism. For Durafill, however, the formation and propagation of tensile cracks on the worn surface is the main wear mechanism. The effects of two different indenters, diamond and enamel, on the basic wear mechanisms are also discussed.     

Synthesis of sulphonated mesoporous phenolic resins and their application in esterification and asymmetric aldol reactions

Mesoporous phenolic resins were functionalized with sulphonic acid groups by four different types of sulphonation procedures: (i) direct sulphonation on the aromatic ring, (ii) alkyl sulphonation of the aromatic ring, and functionalizations of the phenolic hydroxyl surface by using an aryl silane, 2-(4-chlorosulphonylphenyl)ethyl trichlorosilane (iii) or a propyl silane, 3-mercaptopropyltrimethoxysilane (iv). The highest acidity loadings were obtained through direct sulphonation with fuming sulphuric acid (1.90 mmol H⁺ g⁻¹) or chlorosulphonic acid (1.31 mmol H⁺ g⁻¹) and these materials showed the highest conversion (97+ %) in Fischer esterification of acetic acid with propanol. However, the alkyl sulphonic groups, obtained through sulphonation procedure (ii) showed the highest stability in terms of maintenance of their acidity after use in consecutive catalytic runs or leaching treatments. This was demonstrated both through evaluation of the regenerated catalysts in a consecutive esterification run and during a leaching resistance test in aqueous medium. Moreover, the developed sulphonated mesoporous phenolic resins are presented as novel support for the non-covalent immobilization of an l-phenylalanine derived chiral diamine organocatalyst for asymmetric aldol reactions. The immobilization is established by an acid–base interaction between the sulphonic acid group and the amine function. The acidity and in particular the electronic withdrawing environment of the sulphonic acid groups influence enormously the catalytic performance of the non-covalent immobilized chiral diamine catalyst (aromatic > aliphatic).     

丙烯酸酯水性涂料用高分子乳化剂的合成及性能研究

以甲基丙烯酸、苯乙烯、丙烯酸羟乙酯和丙烯酸-2-乙基己酯为主要原料,通过溶液共聚法合成了用于丙烯酸酯水性涂料的高分子表面活性剂.使用FT-IR对合成产物的结构进行了表征,测试了共聚物的表面张力、临界胶束浓度(CMC)、表观黏度,初步探讨了甲基丙烯酸用量对产物表面活性的影响.结果表明,共聚物的表观黏度(异丙醇溶剂,浓度85%)为100～530 mPa·s,具有较低的临界胶束浓度(CMC)(4～9 g/L),最低表面张力降至31.5mN/m(25℃).以此产物为乳化剂,皆能制得体系稳定的丙烯酸酯乳液,其乳胶粒粒径分布均匀.     

纳米技术在牙科复合树脂改良中的应用

以牙科复合树脂现存缺点为背景,对纳米技术对复合树脂的改良情况进行了研究,着重讨论了纳米材料对复合树脂的聚合收缩、抗菌性能和机械性能改良的一系列问题。研究结果表明,使用纳米技术和材料可以很好地改进复合树脂多方面的性能,同时对复合树脂的发展方向和研究前景进行了展望。