Effect of praseodymium on catalytic graphitization of furan resin carbon

We introduced a new catalyst,rare earth element praseodymium,for the catalytic graphitization of furan resin carbon.The extent of graphitization of the furan resin carbon was examined by X-ray diffraction and Raman spectroscopy.The morphology of furan resin carbon was characterized by scanning electron microscopy.The effects of the praseodymium content and the heat-treatment temperature on the catalytic graphitization of furan resin carbon were also investigated.The results indicated that the praseodymium content and the heat-treatment temperature were two important factors on the catalytic graphitization of furan resin carbon and the significant catalytic graphitization was achieved at 2400 ?C and 15 wt.% praseodymium.

Investigation on synthesis of a low cost no-bake furan resin system with a high strength

The synthesis of a low cost no-bake furan resin with a high strength was researched in this paper. Through the analysis of main factors influencing the strength of furan resin, an orthogonal experiment was conducted to optimize synthesis of urea-formaldehyde furan resin with 3% nitrogen. The critical factors and their optimal levels were confirmed, and high strength property was obtained. Subsequently, some active substitute materials, including polyols A agent, methyl alcohol, mother liquid of xylitol, polyols B agent and ethanol, were used for partly substitution of furfural alcohol, the main material component of furan resin. A good combination of the substitute materials was determined to achieve a high strength, and the overall proportion of substitute materials to the resin is 20%. In this study, the substitution mechanism on furan resin was also characterized and analyzed by IR.

Optimization of tensile strength for new type acetone-urea-formaldehyde furan resin using uniform design

In this study,the 24 h tensile strength of new type acetone-urea-formaldehyde furan resin (nitrogen content 3%) was investigated by uniform design optimization.Four independent variables such as acetone:formaldehyde molar ratio (mol/mol),solution pH value,reaction temperature (℃) and reaction time (min) were considered in the experiments.U13(134) uniform design was employed and the equation of 24 h tensile strength model was obtained after 13 experimentations.The 24 h tensile strength was optimized by applying single factor experiments and stepwise non-linear regression analysis.Minitab (Minitab 15 trial version) and MATLAB (R2010a trial version) were used for data analysis.The t-value and p-value indicate that the major impact factors include the interaction effect of solution pH value and reaction temperature (X2X3),the linear terms of acetone:formaldehyde molar ratio (X1),reaction time (X4) followed by the square effects of acetone/formaldehyde molar ratio (X1X1).The optimized results were achieved with the acetone:formaldehyde molar ratio (mol/mol) at 3:1,solution pH value at 6.0,reaction temperature at 70℃,and reaction time at 140 min,respectively.This method can not only significantly reduce the number and cost of the tests,but also provide a good experimental design strategy for the development of furan resin.The investigation shows that the predicted results of 24 h tensile strength are consistent well with the experimental ones.

Substitute materials of furfuryl alcohol in furan resin used for foundry and their technical properties

Based on a special synthesis process of furan resin,the furfuryl alcohol(FA),the main component of typical no-bake furan resins is substituted by ethanol and xylitol mother liquor which is relatively low price and chemically active.Through orthogonal test,the optimal amount of xylitol liquor,ethanol and modifier has been determined.Finally,the test results on technical properties show that the performance can meet the production requirement well,which indicate a success in this substituting attempt.

Curing mechanism of furan resin modified with different agents and their thermal strength

The curing mechanism of furfuryl alcohol and urea-formaldehyde furan resins was investigated using infrared spectroscopy(IR) technique.The curing productions of urea-formaldehyde furan resins modified with different agents(i.e.sorbitol,polyester polyol,phenol and acetone) and the productions of incomplete curing were characterized by differential thermal analysis(DTA) and thermal gravity analysis(TG).The results indicate that except for polyester polyol,the other modifiers have little effect on the thermal strength of urea-formaldehyde furan resin.Furthermore,the thermal strength can be improved at a temperature of higher than 550℃.

Emission of BTEX and PAHs from molding sands with furan cold setting resins containing different contents of free furfuryl alcohol during production of cast iron

At present, furan resin is the largest selling no-bake system of moulding sands. The most commonly used furan no-bake binders(FNB) are condensation products of furfuryl alcohol(FA) urea, formaldehyde and phenol. They are generally cured by exposure to organic sulfonic acids. FNB provide excellent mold and core strength, cure rapidly and allow the sand to be reclaimed at fairly high yields, generally 75%-80%, especially in applications where due allowance is made for the need to keep total sulfur content below 0.1%. However, due to probable carcinogenic properties of furfuryl alcohol, the EU Directive limits the content of this substance(in a monomer form in resin) to 25%. The classification of furfuryl alcohol and the resulting furan resin products has changed from "harmful" to "toxic by inhalation". The aim of this study was to determine the effect of free furfuryl alcohol content in the resin on the emission of harmful substances from the BTEX(Benzene Toluene Ethylbenzene & Xylene) and PAHs(polycyclic aromatic hydrocarbon) group exposed to high temperature and how it affects the emissions allowance of reclaimed sand in the matrix. Three resins from a leading manufacturer were examined, which contain a free furfuryl alcohol content of 71%-72%, about 50% and < 25%, respectively. The hardener for each resin was 65% aqueous solution of paratoluenesulfonic acid. Tests were carried out in semi-industrial conditions where liquid cast-iron was poured into sample sand mold at 1,350 °C. The matrix of the studied sands was reclaimed in the amount of 0, 50%, 100%, respectively.With the increase of free furfuryl alcohol content, the volume of evolved gases decreased. For all resins the main component from the BTEX group dominating in the emitted gases was benzene; however toluene also appeared in the amount of a few percentages. In contrast, ethylbenzene and xylenes occurred only in the gases emitted from resin-bonded sands with the largest furfuryl alcohol content. The increase in the share of reclaimed sands resulted in very significant increase in the volume of gas generated and participation of benzene in these gases. In terms of emission of compounds from the PAHs group virtually for all resins, the total content of these substances was comparable(within the limits of error). The main components were: fluoranthene, pyrene and benzo(a) anthracene.

Synthesis of benzoxazine-based phenolic resin containing furan groups

<正>A novel benzoxazine-based phenolic resin containing furan groups(PFB) was synthesized via simple two-step reactions and the structure of PFB was confirmed by FTIR and ~1H NMR spectra.Differential scanning calorimetry(DSC) showed that the polybenzoxazine cured from PFB had good heat resistance and lower polymerization temperature compared with that of benzoxazine-based phenolic resins.

呋喃基磷杂菲阻燃剂的合成及在阻燃环氧树脂中的应用

以5-羟甲基糠醛、糠胺、三氯氧磷和9,10-二氢-9-氧杂-10-磷杂菲-10-氧化物(DOPO)为原料合成了一种呋喃基磷杂菲阻燃剂(Furan-2DOPO),并利用傅里叶变换红外光谱(FTIR)、核磁共振波谱(^(1)H NMR和^(31)P NMR)对其结构进行了表征.进一步利用Furan-2DOPO对环氧树脂进行阻燃改性,得到一系列阻燃环氧固化物.考察了Furan-2DOPO的用量对阻燃环氧固化物的力学性能、热稳定性以及阻燃性能的影响.研究结果表明,当Furan-2DOPO的添加量(质量分数)仅为5%时(磷质量分数为0.47%),环氧固化物的氧指数达到31.0%,且能够通过UL-94垂直燃烧V-0级测试.与未改性环氧树脂相比,添加2.5%和5%Furan-2DOPO的环氧固化物的最大热释放速率分别下降了31%和35%.此外,2种添加Furan-2DOPO的环氧固化物的拉伸强度均比未改性环氧树脂提升了约28%.炭层分析结果表明,Furan-2DOPO具有良好的催化成炭性能,有利于减少燃烧过程中可燃性气体的逸出,从而提升阻燃性能.

玉米淀粉-糠醛共缩聚树脂塑料的制备

以来自农林的廉价植物提取物——玉米淀粉和糠醛为原料,合成一款生物基塑料淀粉-糠醇-甲醛共缩聚塑料(SFFP)。通过电喷雾电离质谱(ESI-MS)和X射线衍射(XRD)测试,表明淀粉、糠醛和甲醛在酸性条件下进行了共缩聚反应。该生物基SFFP塑料的抗压强度与酚醛(PF)塑料相近。在300℃、氮气处理条件下的重量损失为18%,与PF塑料相比,SFFP具有较好的热降解性。此外,与PF塑料相比,SFFP具有更好的疏水性,且其可再生原材料含量高达87%,具有一定的应用价值。

新型磺化酮醛缩聚物改性呋喃树脂工艺研究

芳烃磺酸是自硬呋喃树脂最佳固化剂,也是目前应用最多固化剂种类之一,相对于高游离酸的固化剂,它更有利于提高呋喃树脂砂的后期强度和树脂砂型(芯)韧性。目前在呋喃树脂工艺改进中,更多是降低呋喃树脂的糠醇含量,从而达到降低呋喃树脂的生产成本目的。本文试图用磺化酮醛缩合物来改性呋喃树脂达到上述改进呋喃树脂与固化剂的双重目的。用磺化酮醛缩合物改性呋喃树脂,可以降低呋喃树脂的糠醇含量节约成本;同时在混砂过程中,固化剂中游离酸将该树脂中的磺化缩合物的磺酸基的盐变成磺酸基,相当于降低了固化剂中的游离酸含量,并改善了呋喃树脂砂芯和砂型的性能。文中对该磺化酮醛缩合物合成工艺条件与改性呋喃树脂的适应性方面进行研究,得出较佳的合成条件:有机酮F与醛摩尔比1∶4,磺化试剂S与有机酮F摩尔比为1∶0.3;该磺化酮醛缩合物较适用于中氮和低氮呋喃树脂的改性。

玻璃钢船体渗漏的粘接修补技术研究

介绍了玻璃钢船体破裂粘接修复工艺,阐述了玻璃钢船体渗漏的原因和整个粘接修复过程。通过气压法确定渗漏位置,然后采用丙酮清洗渗漏处,并用砂纸打磨,选用环氧底胶、环氧-呋喃胶和玻璃布为修复材料,通过交替涂胶和贴敷玻璃布的工艺完成玻璃钢船体渗漏的粘接修复过程,最后利用水压试验法来检测修复效果。

呋喃树脂砂抗拉强度影响因素研究

利用“8”字试块拉伸实验研究了树脂与固化剂加入量、微粉含量以及含水量对呋喃树脂砂抗拉强度的影响。试验结果表明,随着树脂加入量的增加,试块终止抗拉强度逐渐增大,初始强度先增加后减小;随着固化剂加入量增加,试块的终止抗拉强度先增加后减小。当树脂加入量占砂1%,固化剂占树脂80%时达到峰值。随微粉含量、含水量的增加,试块的抗拉强度逐渐下降,因此建议再生砂微粉含量≤2%,含水量≤0.2%。

呋喃树脂砂生产球墨铸铁件的色差问题研究

对自硬呋喃树脂砂生产球墨铸铁件的表面球化衰退引起铸件色差的问题进行研究,并作金相组织分析,根据分析结果采用FQ30pro防渗硫涂料,阻隔或中和型砂中的S进入铸件表层,解决了球墨铸铁件的表层球化不良引起的色差问题。

硅砂平均细度对呋喃树脂砂性能的影响

分析不同的AFS平均细度、树脂加入量对呋喃树脂砂的砂型性能影响,建立起AFS平均细度、树脂加入量与砂型性能之间的关系曲线,确定出呋喃树脂砂的AFS平均细度和树脂加入量的最佳值。试验研究发现,呋喃树脂砂的AFS平均细度控制在34~42、树脂加入量控制在0.8%~1.0%、固化剂加入量占树脂的40%、砂型抗压强度控制在2.5~4.0MPa,可以得到最优的型砂性能,从而生产出高品质的中小铸铁件。

消失模工艺在机床主轴箱铸件上的应用研究

概述了机床类铸件常用呋喃树脂砂工艺的缺点,应用消失模工艺于某机床主轴箱铸件的生产,介绍了铸件的铸造工艺设计及主要缺陷预防控制方法,生产实践证明消失模工艺是可以成功应用于机床类铸件,生产出的主轴箱铸件质量稳定,合格率达到98%以上。

呋喃树脂对煤沥青流变性能的影响

采用旋转黏度计测定了含有不同比例呋喃树脂的煤沥青的表观黏度.考察了呋喃树脂对煤沥青表观黏度、残炭率及软化点的影响.同时,采用扫描电镜(SEM)研究了添加呋喃树脂后煤沥青的表面形貌.结果表明,添加质量分数为3.6%～9.0%的呋喃树脂使煤沥青在达到相同黏度值时温度下降5℃～15℃,而残炭率不下降;由于呋喃树脂使煤沥青分子隔开从而改善了煤沥青的流动性能;另外加入适量的呋喃树脂可降低煤沥青的黏流活化能,有利于煤沥青在较宽温度范围内进行工艺操作.

呋喃树脂改性煤沥青的机理及热行为研究

以呋喃树脂为改性剂对煤沥青进行了改性,采用傅立叶红外光谱(FT-IR)和扫描电镜(SEM)对呋喃树脂改性煤沥青的机理进行了分析;采用热重和示差扫描量热技术(TG-DSC)对改性前后煤沥青的热解行为进行了分析.实验结果表明,呋喃树脂在煤沥青中起增塑作用,其增塑过程通过四步完成,呋喃树脂与煤沥青发生增塑作用时需要吸收热量;呋喃树脂改性煤沥青的耐热性提高,呋喃树脂对煤沥青的残炭率影响不大.

改性呋喃树脂固砂剂用于热采稠油井防砂

本文报道了改性呋喃树脂固砂剂的组成及各种配方变量、固化温度、热老化、岩芯原始渗透率、介质浸泡、蒸汽冲刷等对固结砂岩芯抗压强度和渗透率的影响。这种固砂剂可用于40-350℃温度，形成的人工井壁抗压5-15MPa，渗透率＞0.3μm2，可阻隔粒径＞0．06mm的砂粒。用这种固砂剂在辽河油田锦7、锦45等区块20口热采稠油井和稀油井进行防砂，效果良好。介绍了施工工艺。

有色合金用呋喃树脂砂溃散性的研究

呋喃树脂砂用于有色合金铸造时，由于浇注温度低，型芯的演散性较差。对于薄壁铝合金铸件和厚大型芯该问题尤其明显。为解决这个问题，作者以ＫＪＮ－Ⅲ型呋喃树脂自硬砂为对象，就其在不同加热温度下的温度场、残留强度及热强度进行了系统的研究。通过对树脂添加剂与残留强度之间关系的研究，得到几种较好的树脂添加剂。在合适的加入量下，可使呋喃树脂砂的残留强度下降４０％～８０％，取得了令人满意的结果。

铸造用高强度低气味呋喃树脂合成工艺

针对国内生产的呋喃树脂气味大、游离甲醛含量高的缺欠,采用正交试验法优化呋喃树脂的生产工艺,通过对实验数据的极差分析,获得了最佳的合成工艺,制备出强度较高的呋喃树脂.为进一步降低游离甲醛含量,加入了适量的捕醛剂J,有效地降低了树脂中游离甲醛的含量,同时又保持了树脂砂较高的强度.制备出的呋喃树脂具有强度高、低气味等特点.