Diffusion‐controlled radiochemical oxidation of bisphenol A polysulfone

The radiochemical degradation of bisphenol A polysulfone was investigated under a γ‐ray dose rate of 24 kGy h^?1 up to 30.7 MGy total absorbed dose at 60 °C using gel permeation chromatography, sol–gel analysis, glass transition and rheometry measurements, and oxidation profile measurements by microscopy coupled with Fourier transform infrared analysis in attenuated total reflectance mode. Thin (200 µm) and thick (2 mm) samples were compared. Thin samples undergo mainly chain scissions whereas thick ones undergo mainly crosslinking. The thickness of oxidized layers and, radiochemical yields for chain scissions, crosslinking, oxygen absorption and radical formation were tentatively determined from experimental data in order to determine the influence of oxidative processes on radiochemical ageing and to establish the nature of the crosslinking reactions. Copyright © 2010 Society of Chemical Industry     

影响螺纹锁固厌氧胶性能的因素研究

以BPA2EODMA(乙氧化双酚A二甲基丙烯酸酯)和EA(双酚A环氧丙烯酸酯)为主要原料、异丙苯过氧化氢(CHP)为引发剂、1,4-萘醌为阻聚剂、N,N-二甲基苯胺为促进剂和糖精为助促进剂,采用单因素试验法优选出厌氧胶的最佳配方。结果表明:当m(BPA2EODMA):m(EA)=3:7、w(CHP)=3.0%、w(N,N-二甲基苯胺)=0.8%、w(糖精)=0.5%和w(1,4-萘醌)=0.03%时,厌氧胶的综合性能较好,其剪切强度达到26 MPa,施工性能及储存稳定性能俱佳。     

Experimental study of the influence of raw material impurities on yellowness index of transesterification polycarbonate

This article covers a quantitative experimental study on the influence of raw materials and materials of construction impurities on polycarbonate color as expressed by a solution yellowness index. Major impurities in the production process were identified, synthesized, and spiked into the baseline materials. A fractional factorial experimental design was executed to provide some information of the influence of impurities as corresponding to levels similar to those occurring in the manufacturing practice. Analysis of the experimental design showed that isopropenylphenol (IPP), methoxyphenyl benzoate (MOB) and 9,9‐dimethylxanthene (DMX) are the main producers of color bodies. A quantitative expression was derived which can be used to predict manufacturing problems with regards to color. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Al2O3/环氧树脂-氰酸酯复合材料反应动力学及力学性能

以双酚A型环氧树脂(E51)和双酚A型氰酸酯(BCE)为原料,研究E51改性BCE共固化反应机制。同时,以E51-BCE为基体树脂,溶胶-凝胶法(Sol-Gel)自制Al2O3为增强体,制备Al2O3改性E51-BCE (Al2O3/E51-BCE)复合材料。通过非等温DSC确定了E51-BCE体系的固化工艺及固化反应动力学,并根据Kissinger法和Ozawa法求得体系的表观活化能分别为66.13 kJ/mol和69.46 kJ/mol。利用红外光谱跟踪固化体系在起始固化温度为160℃、 180℃时的反应历程,结果表明:起始固化温度在160℃时,以E51与BCE直接反应为主;起始固化温度在180℃时, BCE反应活性提高,以BCE自聚反应为主,生成三嗪环的速率加快,少量的BCE直接与E51反应生成恶唑啉结构。对Sol-Gel法自制Al2O3进行FTIR和TEM表征,结果表明:Al2O3为短纤维状的晶体,表面含有少量羟基。SEM结果显示:Al2O3为分散相,与基体间界面模糊, Al2O3/E51-BCE复合材料的脆断面裂纹不规则,为典型的韧性断裂;当Al2O3掺杂量为3wt%时, Al2O3在基体中分散均匀, Al2O3/E51-BCE复合材料的冲击强度和弯曲模量分别为24.2 kJ/m2和2.54 GPa,比基体树脂的冲击强度和弯曲模量分别提高53.65%和22.12%,力学性能得到明显改善。     

THIRD PHASE FORMATION IN THE SOLVENT EXTRACTION SYSTEM FeCl3-HCl-H20-DIPE

The influence of the initial aqueous concentrations and the temperature on the volumes and compositions of the phases obtained in the FeCl₃-HCl-H₂0-DIPE system have been investigated.The low temperature limit to the three phase system suggests that the appearance of the second organic phase is associated with an increase in entropy due to the separation a weakly ordered, predominantly solvent, phase.     

高铁酸盐和臭氧氧化法降解水中双酚A的研究

通过烧杯试验,对比研究了不同因素对高铁酸盐和臭氧氧化降解双酚A的影响,并对试验过程中的生物毒性进行了对比分析。试验结果表明:针对质量浓度为1 mg/L的双酚A模拟废水,在高铁酸盐和臭氧的投加量分别为5.0和1.20 mg/L的条件下,高铁酸盐降解双酚A的能力更强,去除率达到91.6%,而臭氧氧化法仅为80.9%;同时,高铁酸盐法具有更广的pH值(3~11)和温度(10~50℃)适应性。不同的干扰离子对氧化体系的影响不同,HCO3-对2个氧化体系均具有一定的促进作用;Fe3+的存在具有催化作用,有利于臭氧氧化降解双酚A,但是不利于高铁酸盐的稳定性从而不利于双酚A的脱除。2种方法处理后水的生物毒性均随反应时间的延长呈先升高后降低的趋势,相对而言,高铁酸盐法对处理后水的毒性控制效果更佳。     

Reactive Alder‐ene blend of diallyl bisphenol A novolac and bisphenol A bismaleimide: synthesis,cure and adhesion studies

A novel, addition‐curable novolac resin (ABPF) was synthesized by the reaction of diallyl bisphenol A with formaldehyde using p‐toluene sulfonic acid as the catalyst. The synthesis conditions were optimized to obtain soluble polymer of desirable molecular weight distribution which was characterized by FT‐IR, NMR and SEC. ABPF was reactively blended with bisphenol A bismaleimide (BMIP) and cured through an Alder‐ene reaction at high temperatures. The cure characteristics of BMIP–ABPF blend with a maleimide:allyl phenol stoichiometry of 1:1 were studied using FT‐IR, DSC and DMA, which evidenced the multi‐step cure reactions taking place in the system. Cure optimization was evaluated by DSC, DMA and adhesive property tests. The moderately crosslinked blend was conducive for achieving the optimum adhesive properties on aluminium substrates. Retention of the adhesive properties was greater than 100% at 150 °C. © 2001 Society of Chemical Industry     

Application of accelerated carbonation with a combination of Na2CO3 and CO2 in cement-based solidification/stabilization of heavy metal-bearing sediment

The efficient remediation of heavy metal-bearing sediment has been one of top priorities of ecosystem protection. Cement-based solidification/stabilization (s/s) is an option for reducing the mobility of heavy metals in the sediment and the subsequent hazard for human beings and animals. This work uses sodium carbonate as an internal carbon source of accelerated carbonation and gaseous CO₂ as an external carbon source to overcome deleterious effects of heavy metals on strength development and improve the effectiveness of s/s of heavy metal-bearing sediment. In addition to the compressive strength and porosity measurements, leaching tests followed the Chinese solid waste extraction procedure for leaching toxicity – sulfuric acid and nitric acid method (HJ/T299-2007), German leaching procedure (DIN38414-S4) and US toxicity characteristic leaching procedures (TCLP) have been conducted. The experimental results indicated that the solidified sediment by accelerated carbonation was capable of reaching all performance criteria for the disposal at a Portland cement dosage of 10 wt.% and a solid/water ratio of 1:1. The concentrations of mercury and other heavy metals in the leachates were below 0.10 mg/L and 5 mg/L, respectively, complying with Chinese regulatory level (GB5085-2007). Compared to the hydration, accelerated carbonation improved the compressive strength of the solidified sediment by more than 100% and reduced leaching concentrations of heavy metals significantly. It is considered that accelerated carbonation technology with a combination of Na₂CO₃ and CO₂ may practically apply to cement-based s/s of heavy metal-bearing sediment.     

Phosphorus‐containing epoxy resin for an electronic application

A phosphorus‐containing epoxy resin, 6‐H‐dibenz[c,e][1,2] oxaphosphorin‐6‐[2,5‐bis(oxiranylmethoxy)phenyl]‐6‐oxide (DOPO epoxy resin), was synthesized and cured with phenolic novolac (Ph Nov), 4,4′‐diaminodiphenylsulfone (DDS), or dicyandiamide (DICY). The reactivity of these three curing agents toward DOPO epoxy resin was found in the order of DICY > DDS > Ph Nov. Thermal stability and the weight loss behavior of the cured polymers were studied by TGA. The phosphorus‐containing epoxy resin showed lower weight loss temperature and higher char yield than that of bisphenol‐A based epoxy resin. The high char yields and limiting oxygen index (LOI) values as well as excellent UL‐94 vertical burn test results of DOPO epoxy resin indicated the flame‐retardant effectiveness of phosphorus‐containing epoxy resins. The DOPO epoxy resin was investigated as a reactive flame‐retardant additive in an electronic encapsulation application. Owing to the rigid structure of DOPO and the pendant P group, the resulting phosphorus‐containing encapsulant exhibited better flame retardancy, higher glass transition temperature, and thermal stability than the regular encapsulant containing a brominated epoxy resin. High LOI value and UL‐94 V‐0 rating could be achieved with a phosphorus content of as low as 1.03% (comparable to bromine content of 7.24%) in the cured epoxy, and no fume and toxic gas emission were observed. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 353–361, 1999