聚乙烯醇缩丁醛-酚醛树脂-环氧树脂结构胶的研制

在氢氧化钠(NaOH)催化作用下,以苯酚和甲醛为主要原料,合成了甲阶PF(酚醛树脂),并测定了游离甲醛含量和收率;然后以PVB(聚乙烯醇缩丁醛)和甲阶PF为EP(环氧树脂)的柔韧改性剂、咪唑为固化剂,合成了三元共聚结构胶。研究结果表明:采用单因素试验法优选出制备甲阶PF的最佳工艺条件为n(F):n(P)=1.5:1、反应温度80℃和反应时间3 h;此时,甲阶PF的收率为92%,游离甲醛含量为1.4%。当m(PF):m(EP):m(PVB)=100:30:20、固化工艺为120℃/3 h时,制成的三元共聚结构胶用于铝板-铝板的粘接时,其剥离强度为15.72 N/cm、粘接强度为5.68 MPa。     

甲阶酚醛树脂酯催化反应动力学及产物热分析

利用凝胶转化率的测定,研究了醋酸甘油酯(三醋酸甘油酯、二醋酸甘油酯、一醋酸甘油酯)对甲阶酚醛树脂交联反应的催化动力学,并对交联产物进行了热分析。结果表明,醋酸甘油酯对甲阶酚醛树脂的催化交联反应是一级动力学反应,三醋酸甘油酯、二醋酸甘油酯、一醋酸甘油酯等作催化剂时该反应的表观活化能分别为:11.45 kJ/mol、22.53 kJ/mol和29.27 kJ/mol;交联反应主要由甲阶酚醛树脂中的羟甲基引起,其酯催化交联产物比热固化产物更容易发生热分解。     

热固性PF/PU复合体系的收缩性能

将端羟基封端和端羧基封端的聚氨酯 (PU)预聚物分别与酚醛树脂 (PF)固化 ,制备了两种体系的复合物。通过测试其体系收缩率 ,结果表明 :随着聚氨酯预聚物加入量的增加 ,PF/PU共混物的体积收缩率明显变小 ,并能达到负值。端羧基PU的低收缩性能更为显著 ,当其加入量在 5 相似文献   

木质素酚醛泡沫保温材料的制备与性能研究(摘要)

采用一种新的方法将木质素应用到甲阶酚醛树脂中.通过低温下氧化降解木质素,使降解产物中含有多种低分子量的酚类小分子化合物,提高了木质素的反应活性;采用木质素磺酸钙的氧化降解产物替代苯酚50％制备甲阶酚醛树脂,进一步制备性能良好的酚醛泡沫;研究木质素的引入对甲阶酚醛树脂和酚醛泡沫保温材料性能的影响.主要研究内容和结果如下:     

甲醛/苯酚配比对酚醛泡沫塑料性能的影响

将甲醛溶液、多聚甲醛共同与苯酚反应,在NaOH碱性催化剂作用下,通过逐步共聚制备可发性甲阶酚醛树脂(PF),然后将可发性甲阶PF与环保型发泡剂、匀泡剂和自制复合酸固化剂混合制备了阻燃绝热PF泡沫塑料.通过对甲醛/苯酚配比(物质的量之比即F/P)进行单因素分析,重点研究了制得的PF泡沫塑料的泡孔结构、力学性能、绝热性能和阻燃性能,并通过锥形量热仪对PF泡沫塑料的燃烧性能进行了分析.结果表明,当F/P=2.0时,制得的PF泡沫塑料泡孔均匀致密,其孔径为268 μm,弯曲强度为0.24 MPa,压缩强度为0.39 MPa,热导率为0.046 W/(m·K),氧指数为54.3%,热释放速率为0.57 kW/m2,烟灰产率仅为9.6 m2/m2,峰值CO产量仅为1.8584 kg/kg.     

木质素糠醛改性甲阶酚醛树脂的合成

采用木质素和糠醛改性普通甲阶酚醛树脂。运用正交实验法得到木质素糠醛改性甲阶酚醛树脂的最佳反应条件,通过IR,DSC,TG分析和压缩性能测试对产物的热性能和力学性能进行了研究。结果表明,在苯酚100g,木质素40g,甲醛116.54g,糠醛34.28g,反应温度85℃,反应时间3h,体系pH值9的条件下得到的改性甲阶酚醛树脂固含量70%～80%,黏度850～1000mPa.s(25℃),热分解温度为258℃,与普通甲阶酚醛树脂(263℃)相比,耐热性稍差。所制备的改性酚醛塑料的压缩强度为1.07MPa,比普通酚醛塑料(0.73MPa)高,木质素和糠醛的引入提高了泡沫塑料的韧性。     

甲阶酚醛树脂的合成及其发泡性能研究

以苯酚、甲醛为原料,氢氧化钠为催化剂,合成了可发性甲阶酚醛树脂。采用物理发泡剂、复合酸固化剂对所制备的甲阶酚醛树脂进行发泡。研究了醛酚摩尔比、反应时间对可发性甲阶酚醛树脂的分子结构、物理性能及其可发性的影响。结果表明:随着醛酚摩尔比的增大,甲阶酚醛树脂的黏度逐渐提高,凝胶时间逐渐缩短。当醛酚摩尔比一定时,随着反应时间的延长,甲阶酚醛树脂的黏度和固含量均增大,凝胶时间缩短。当醛酚摩尔比为1.5、反应时间为200 min时,合成的甲阶酚醛树脂具有良好的可发性。     

PF用低收缩添加剂的研究

通过调整物料配比合成了端羟基封端和端羧基封端的聚氨酯 (PU)预聚物 ,并分别与酚醛树脂 (PF)固化 ,制备了两种低收缩体系的复合物 ,利用红外光谱对其结构进行表征。通过测试固化物的体系收缩率表明 :随着聚氨酯预聚物加入量的增加 ,PF/PU共混物的体积收缩率明显变小 ,并能达到负值。端羧基PU的低收缩性能更为显著 ,当其加入量在 5 相似文献   

高羟甲基低游离醛甲阶酚醛树脂的制备

根据醛过量,碱催化制备甲阶酚醛树脂,采用正交试验法设计不同的实验方案,并通过盐酸羟胺法和碘量法分别滴定每组合成树脂中的游离醛含量和羟甲基含量,最终确定制备高羟甲基低游离醛甲阶酚醛树脂的最佳工艺,即反应温度为80℃,甲醛与苯酚比为1.2,催化剂与苯酚的摩尔比为0.025,反应时间为90min。并通过红外分析进一步确定甲阶酚醛树脂中高羟甲基含量。     

腰果酚改性甲阶酚醛树脂的合成及其泡沫性能研究

用腰果酚代替部分苯酚改性酚醛树脂,制备可发性甲阶酚醛树脂。并讨论了腰果酚替代量对改性酚醛树脂性能及其泡沫性能的影响,通过红外光谱仪、热重分析仪对树脂结构及热稳定性进行表征,运用万能电子试验机对甲阶酚醛树脂泡沫的力学性能进行了研究。结果表明:当腰果酚替代量为10%时,制得的树脂黏度为4650mPa·s,树脂中游离苯酚含量从6.72%降为5.45%,游离甲醛含量从1.17%降为0.68%,甲阶酚醛树脂泡沫压缩强度达到最大值0.20MPa,但树脂热稳定性及甲阶酚醛树脂泡沫阻燃性有所下降。     

Resol‐type phenolic resin from liquefied phenolated wood and its application to phenolic foam

A liquefied wood‐based resol resin was prepared with excellent yield by a reaction of liquefied wood and formaldehyde under alkaline conditions. The effects of various reaction parameters on the extent of the yield of the resol resin, unreacted phenol content, and viscosity were investigated. Milder resol resinification conditions were required as compared to those used in conventional methods. The liquefied wood‐based resol resin was successfully applied to produce phenolic foam using appropriate combinations of foaming agents. Diisopropyl ether with a relatively higher boiling temperature was suitable for the foaming of liquefied wood‐based resol resin. Hydrochloric acid and poly(ethylene ether) of sorbitan monopalmitate were used as a catalyst and a surfactant, respectively. The obtained foams showed satisfactory densities and compressive properties, comparable to those of foams obtained from conventional resol resin. Foams with low density were obtained by the blending of liquefied wood‐based resol resin and conventional resol resin. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 468–472, 2002; DOI 10.1002/app.10018     

固体可熔性酚醛树脂模塑料的研制

合成了羟甲基型固体可熔性酚醛树脂(resol),将resol和novolak树脂复配,加入质量分数50%左右的玻璃纤维,采用高速混炼机混合,加入增塑剂,应用双辊塑炼机混炼该组成物,制备出高端整流子用酚醛模塑料(EA-5801J等)。对该注射料的耐高温性能和力学性能等进行了测试,结果表明,该模塑料耐高温性能和力学性能优于热塑性酚醛树脂模塑料,而注射加工性能优于液体resol树脂模塑料。     

用磷酸酯衍生物对可溶酚醛树脂的阻燃改性研究

本文采用红外光谱法及元素磷含量测定法,对改性树脂进行了热化学和热物性的研究,并比较了改性前后的氧指数.     

Dynamic mechanical analysis of fiber-reinforced phenolics

Dynamic mechanical analysis (DMA) was used to investigate the thermomechanical behavior and the effects of postcuring on a range of glass-reinforced phenolics. The materials examined were a pure resol (reinforced with S- and E-glass), a pure novolac (reinforced with S-glass), and three derivatives of the resol and/or novolac: a resol/novolac blend, a phenolic–furan graft copolymer, and a rubber-modified resol (all reinforced with S-glass). The blend and copolymer were prepared to obtain phenolic resins with improved impact strength, without degeneration of their high-temperature performance. They have a more loosely crosslinked structure compared to the pure resol or novolac. The rubber-modified resol was prepared with the intention of reducing the brittleness of the resin structure by incorporating an elastomeric phase within the resol resin matrix. It was found that the stiffness and glass transition temperature (T_g) of the materials could be increased by postcuring, which also produced a decrease in their damping capacity. Knowing that the postcure process is a function of time and temperature, a master curve was constructed that allowed prediction of the T_g of the resol/novolac blend over a broad range of postcure times and temperatures. The effect of frequency on the storage modulus of the pure resol (S-glass), copolymer, and blend was also studied from 0.01 to 100 Hz. Master curves were constructed by time–temperature superpositioning that allowed prediction of the storage modulus at times and temperatures that are not experimentally accessible. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 649–658, 1999     

自凝性松香改性酚醛树脂的合成研究

以两步法合成自凝性松香改性酚醛树脂,重点研究了酚醛浆的合成,通过考察酚醛摩尔比、催化剂用量、反应温度和反应时间对酚醛浆缩合反应的影响,得到适宜的酚醛浆合成条件:酚醛摩尔比1:1:5,催化剂用量为对叔丁基苯酚质量的3％,反应温度60℃,反应时间2．5-3 h。并对酚醛浆进行了GPC、VPO及红外光谱分析。利用该酚醛浆合成了具有良好自凝性的松香改性酚醛树脂。     

Structure‐properties relationship in resol/montmorillonite nanocomposites

Polymer/layered silicate nanocomposites were prepared, adding modified, and nonmodified montmorillonites to a resol resin. It was observed that the composites exhibited an intercalated disordered structure by means of X‐ray diffraction (XRD) and transmission electronic microscopy. The crosslinking density of the resol network was greatly influenced by the presence and type of clay that was added to the resin. The composites filled with the modified montmorillonites showed a lower glass transition temperature value as well as a higher degradation peak at ～ 400°C, which is characteristic of the degradation of methylene bridges, indicating a decrease in the crosslinking density of the resol network when modified clays are added. Resol/unmodified montmorillonite composites exhibited different behavior comparing to the other composites and the resol. A higher thermal resistance was observed in the fragmentation zone and a different tan δ response was seen in the DMA analysis. These differences in the behavior of the composites could be because of the interaction between the resol prepolymer and the clay modifiers and as a result of their chemical compatibility. The hardness and elastic modulus of the resol were improved with the addition of clays. However, higher values were obtained for the composite made with the more dispersed montmorillonite. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

可发性酚醛树脂的合成和考评

概述了甲阶酚醛树脂的合成方法,并提出了以绝热温升和温升时间来考评可发性酚醛树脂化学反应特性的观点。与传统热反应考评参数相比较,结果认为化学反应参数和热反应参数不可相互替代,两者结合能较全面反映可发性酚醛树脂的性能。     

The curing behavior of resol. III. Effect of alkali metal hydroxides and alkaline earth metal hydroxides as catalyst for the cure of resol

The effect of the addition of cure catalysts on the cure acceleration of ammonia free resol was investigated by means of Curelastometer. The resol which was prepared by the reaction between phenol and formaldehyde with molar ratio 1:1.2 in the presence of NaOH (0.02 mol to phenol) was neutralized with HCI. Catalyst selected from LiOH, NaOH, KOH, Mg(OH)₂, Ca(OH)₂, Sr(OH)₂, and Ba(OH)₂ was added to the resol, and curing behavior of the resol was examined. Both alkali metal hydroxides and alkaline earth metal hydroxides accelerate the curing of resol. The cure acceleration effect of barium hydroxide is the largest. In the relation between the kinds of catalysts and the cure acceleration effect, the larger the ion radius of catalyst the faster the cure of resol. Cure speed of the resol containing either sodium hydroxide or barium hydroxide as a curing catalyst increases with an increase in the amount of catalyst. Apparent activation energies of curing behavior of the resols containing the cure catalysts were in the range 17.0–21.3 kcal/mol.