Preparation of epoxy–clay nanocomposite and investigation on its anti-corrosive behavior in epoxy coating

An epoxy–clay nanocomposite was synthesized using a quaternary ammonium-modified montmorillonite clay and diglycidyl ether of bisphenol A (DGEBA) type epoxy resin, in order to produce anti-corrosive epoxy coating. Anti-corrosive properties of the nanocomposite were investigated using salt spray and electrochemical impedance spectroscopy (EIS) methods. The results showed an improvement in the barrier and anti-corrosive characteristics of epoxy-based nanocomposite coating and a decrease in water uptake in comparison with pure epoxy coating. Wide-angle X-ray diffraction (WAXD) patterns and transmission electron microscopy (TEM) analysis showed that the interlayer spacing of clays increased after addition of epoxy resin along with applying shear force and ultrasound sonicator. The best performance of this coating was achieved at 3 and 5 wt.% clay concentration.     

TDE-85环氧树脂丙烯酸酯的合成及其UV固化特性的研究

本文研究了TDE-85环氧树脂丙烯酸酯的合成方法，讨论了合成条件（催化剂的种类与用量，反应温度及时间，投料比，反应类型及不饱和酸种类的选择等）对合成反应及合成产物性状的影响。另外，还考察了该合成产物的UV固化特性。     

Rheology of polyflavonoid tannin–formaldehyde reactions before and after gelling. II. Hardener influence and comparison of different tannins

Good correspondence of the gel‐time values obtained by two different methods, G′ = G″ and 1/η₀→0, was observed for different types of natural and modified tannin extracts. The pH presents the predominant effect on both the activation energies and the gel times observed, while the proportion of a paraformaldehyde hardener has a much lesser effect on these parameters. The rate constants of the different phases of the reaction of polycondensation with formaldehyde, both before and after the gel point, were obtained for the six commercial tannin extracts tested. The viscoelastic properties of the different tannins/formaldehyde gels were measured. The gel stiffness S, relaxation coefficient n, and relaxation time λ were determined and their dependence on the proportion of the formaldehyde hardener, on the temperature, and on the type of tannin was determined. The gel stiffness S appears to be influenced considerably by the proportion of the formaldehyde hardener. Its value decreased as the percentage of the hardener increased: This was due to early network immobilization and the resulting lower level of crosslinking resulting from it. The influence on S of the temperature is not very pronounced. The relaxation coefficient n appears to depend mainly on the reactivity of the tannin used: The faster the reactivity, the higher was the value of n. This appears to be valid exclusively in tannin extracts where the colloidal state is still present, while it is not valid in extracts where the colloidal state was eliminated by, for example, solvent extraction. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 864–871, 2002     

α-蒎烯阳离子聚合工艺的改进

以A lC l3/SbC l3为催化剂,用SbC l3逐步滴加方式,通过两步聚合工艺制备了α-蒎烯树脂。通过正交实验,对α-蒎烯调控聚合的各影响因素进行了研究。结果表明,与传统的一步聚合工艺相比,该工艺在保持单体高转化率的同时,使聚合反应变缓,避免了由于反应过快而引起的聚合产物中低聚体含量高,Mn下降的现象;有效提高了聚合物的软化点;降低了聚合物的色值。在优化工艺条件下,催化剂用量比传统工艺减少30%以上,制得的α-蒎烯树脂软化点为138℃(环球法),色泽3(铁钴色),得率达81.0%,软化点提高8℃以上,色泽降低2级以上。产品各项指标均超过了我国行业标准LY/T1453—1999特级水平。     

Viscoelastic Behavior, Thermodynamic Compatibility, and Phase Equilibria in Block Copolymer-Based Pressure-Sensitive Adhesives

The viscoelastic behavior, thermodynamic compatibility, and phase equilibria in block copolymer-based pressure-sensitive adhesives were investigated. The block copolymers investigated were: (1) polystyrene-block-polybutadiene-block-polystyrene (SBS) copolymer (KRATON® D-1102, Shell Development Company) and (2) polystyrene-block-polyisoprene-block-polystyrene (SIS) copolymer (KRATON® D-1107, Shell Development Company). The tackifying resins investigated were: (1) WINGTACK® 86 (Goodyear Tire & Rubber Company) and (2) PICCOTAC® 95BHT (Hercules Inc.). Samples of various compositions were prepared by a solution-casting method with toluene as solvent. Measurements of dynamic storage modulus (G'), dynamic loss modulus (G'), and loss tangent (tan δ) were taken, using a Rheometrics Mechanical Spectrometer. It was found that: (1) both WINGTACK 86 and PICCOTAC 95BHT were equally effective in decreasing the plateau modulus (G^O_N), and increasing the glass transition temperature (T_g) of the polyisoprene midblock of KRATON 1107; and (2) WINGTACK 86 was very effective in decreasing the G^O_N and increasing the T_g of the polybutadiene midblock of KRATON 1102, whereas PICCOTAC 95BHT was not. The observed difference between WINGTACK 86 and PICCOTAC 95BHT in decreasing the G^O_N and increasing the T_g of the polybutadiene midblock of KRATON 1102, whereas PICCOTAC 95BHT was not. The observed difference between WINGTACK 86 and PICCOTAC 95BHT in decreasing the G^O_N and increasing the T_g of the polybutadiene midblock of KRATON 1102 (perhaps to SBS block copolymers in general) is explained by the values of the interaction parameter for WINGTACK 86 and KRATON 1102, and for PICCOTAC 95BHT and KRATON 1102. The interaction parameter was determined, using the piezoelectric quartz sorption method. Phase diagrams were constructed for the four block copolymer/tackifying resin systems investigated, using information obtained from both dynamic viscoelastic measurements and optical microscopy. It was found that when mixed with KRATON 1102, PICCOTAC 95BHT formed separate domains whereas WINGTACK 86 did not over the range of concentrations and temperatures investigated. This confirms the evidence obtained from two other independent experimental techniques, namely, dynamic viscoelastic measurements and the piezo-electric sorption method. We have concluded from the present study that PICCOTAC 95BHT is not as an effective tackifying resin as WINGTACK 86, when each is mixed with KRATON 1102. It is pointed out further that information on the order-disorder transition temperature T_r, which was determined from a rheological technique proposed by us, is valuable in determining optimal processing conditions for block copolymer-based pressure-sensitive adhesives.     

催化裂解废旧不饱和聚酯树脂新技术

对不饱和聚酯树脂 (UPR)废料裂解制原料油技术进行了研究 ,系统地考察了催化裂解反应工艺条件。试验结果表明 ,催化裂解所需反应温度为 40 0～ 45 0℃ ,反应时间为 70～ 80min ;剂油比 1∶5 ;试验对 4种催化剂的催化性能进行了评价 ,研究表明单独使用YB -2催化剂 ,液相产品收率为 5 8.2 2%～ 5 9.1 4% ;YB -1和YB -2混合使用 ,最高液相产品收率为 68.76%。     

Investigation on the properties of a three‐component copolymer consisting of tris(allylphenoxy) triazine monomer and a diamine‐chain‐extension bismaleimide

A new type of modified bismaleimide resin was obtained by copolymerization between tris(allylphenoxy)triazine monomer (TAPT) and an aromatic diamine‐chain‐extension bismaleimide [e.g., 4,4′‐diaminodiphenylmethane (DADPM)‐chain‐extension 4,4′‐bismaleimidodiphenylmethane (BMDPM)]. The new three‐component‐polymer system had good processibility and mechanical properties. Better results were obtained when the weight ratio of TAPT to the DADPM‐chain‐extension BMDPM resin was 30%. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 475–480, 2004     

Relationship between chemical degradation and thickness loss of an amine-cured epoxy coating exposed to different UV environments

The relationship between chemical degradation and thickness loss of an unpigmented, non UV-stabilized, crosslinked amine-cured epoxy coating exposed to three UV conditions was investigated. Spin-coated samples having a thickness of approximately 7 μm on an Si substrate were prepared from a stochiometric mixture of a bisphenol A epoxy resin and a tetra-functional amine curing agent. Samples were exposed outdoors and to two accelerated laboratory UV environments. Chemical degradation and thickness loss were measured by transmission Fourier transform infrared spectroscopy (FTIRS) and laser scanning confocal microscopy (LSCM), respectively. In addition, surface roughness and morphological changes were measured by atomic forcemicrosocopy (AFM) and LSCM. Substantial chemical degradation, thickness loss, and morpholocal changes occurred in the exposed films, and the rate of chemical degradation was greater than that due to the thickness loss. This additional chemical loss was attributed to an inhomogeneous degradation process in which nanoscale localized depressions initiate at certain sites on the surface, which then enlarge and deepen with exposure time. The results of this study provide a better understanding of the degradation mechanism and should lead to the development of scientific-based models for predicting the service life of crosslinked amine-cured epoxy coatings. Presented at the 82nd Annual Meeting of the Federation of Societies for Coatings Technology, October 27–29, 2004, in Chicago, IL     

GRADIENT OF THE MECHANICAL MODULUS IN GLASS-EPOXY-METAL JOINTS AS MEASURED BY BRILLOUIN MICROSCOPY

The newly developed Brillouin microscopy is used for the first time to measure in situ the longitudinal elastic stiffness coefficient in the GHz-range inside of glass-epoxy-metal joints as a function of distance from the substrates. Interphases with a local variation of mechanical properties are quantitatively characterized. These interphases possess unexpected widths of tens to hundreds of microns. Inside the interphases, the spatial variation of the longitudinal stiffness coefficient depends on the type of substrate, on the curing conditions for the epoxy and probably on the distribution of internal stresses. The obtained spatial mechanical profiles provide valuable insight into the morphology-driven mechanics of the interphase, but additional information is needed for a full understanding of their physical and chemical origin. The presented results prove the sensitivity of the Brillouin microscopy; the elastic stiffness coefficients are detected with an accuracy in the subpercentage range. The spatial resolution is better than 10 µm.     

ASPECTS OF JOINT DESIGN AND EVALUATION IN THICK-ADHEREND APPLICATIONS

Structural adhesives are gaining wide recognition by industry as they offer engineering designers greater flexibility to achieve economic and technical advantages. In the marine industry there are potential applications for adhesives in various types of construction, for example, thick steel and composite adherends, (typically 5-15 mm thick). The applications include panels and large pipes. This article is largely concerned with the use of two-part epoxy adhesives. The purpose of this article is to understand and evaluate the weaknesses of adhesives and adherends, in relation to specific applications and to use design and material selection to alleviate them. This understanding can be extended to other thick adherend applications. This article will also highlight the impact of structural epoxy adhesive technology on the design and fabrication of steel, composite, and hybrid constructions. The benefits and inherent limitations that can accrue are quantified through three case studies related to thick adherend connections.