酚醛树脂固化动力学研究及其耐热性能评价

利用差示扫描量热(DSC)法分析了甲醛、苯酚物质的量之比为1.9:1、1.7:1、1.5:1、1.3:1时酚醛树脂(PF)的固化性能,采用Kissinger法计算了4批PF固化反应的表观活化能。用热失重分析(TG)法对4批PF的耐热性能进行了考察。试验结果表明,甲醛、苯酚物质的量之比为1.7:1时,PF的固化反应活化能最低,即固化时需要较少的热量,易固化,其耐热性能最好。     

酚醛树脂耐热改性的研究

以腰果壳油、苯酚及甲醛为原料制备了改性酚醛树脂,通过红外光谱、DSC及TG分析研究了原料配比对产物性能的影响。结果表明,当甲醛(37%水溶液)用量为97.30g,苯酚用量为56.40g,腰果壳油用量为121.60g,氨水用量为30.00 g时合成的改性酚醛树脂的耐热性最佳,热失重温度在400℃以上,非常适合用作高温摩擦制动材料的胶粘剂。     

环保可发性甲阶酚醛树脂的合成及性能研究

采用多聚甲醛代替37%甲醛溶液与苯酚逐步加成聚合,合成可发性甲阶酚醛树脂。通过粘度、固含量、游离苯酚和甲醛含量及凝胶时间测定以及IR,GPC和TG分析研究了多聚甲醛-苯酚物质的量比为1.8∶1条件下,缩聚反应温度及催化剂加入量对可发性甲阶酚醛树脂性能的影响。结果表明,缩聚反应温度为90℃,催化剂质量分数为5%(以苯酚质量计)时,可得到性能优良的可发性甲阶酚醛树脂,其性能如下:粘度2.6 Pa·s,游离甲醛质量分数1.23%,游离苯酚质量分数5.13%,热失重质量残留率50%以上。     

三聚氰胺苯酚甲醛玻璃纤维压塑料的研制

介绍三聚氰胺苯酚甲醛树脂合成机理及合成步骤,三聚氰胺苯酚甲醛玻璃纤维压塑料的制备和性能,表明该材料在力学性能和耐热性方面较三聚氰胺甲醛玻璃纤维压塑料优异。     

多聚甲醛与苯酚物质的量比对可发性甲阶酚醛树脂性能的影响

采用多聚甲醛代替37%的甲醛溶液,在20%NaOH水溶液催化下与苯酚逐步加成聚合,合成了可发性甲阶酚醛树脂。研究了多聚甲醛与苯酚物质的量比(F/P)对合成树脂固含量、粘度、游离苯酚、游离甲醛、凝胶时间、分子结构、分子质量、树脂热性能及泡沫性能的影响。结果表明,F/P值为1.8时,可得到性能优良成本较低的可发性甲阶酚醛树脂,树脂粘度1.4 Pa.s,游离甲醛质量分数1.17%,游离苯酚质量分数6.72%,羟甲基指数1.41,树脂分子质量在240左右,耐热性较好。     

酚醛树脂的循环水洗和缩合回收——一项减少酚水污染、增产树脂的有效措施

苯酚甲醛树脂是当前化工企业防腐施工中的常用原料。沈阳化工厂防腐车间生产的防腐通用型酚醛树脂是以碳酸钠为催化剂,用量为苯酚的百分之一。苯酚与甲醛的克分子比为1:1.4。反应釜每次投料量:苯酚约74公斤,38～42％的甲醛为90公斤左右。树脂的合成步骤顺次为计量投料、回流反应、盐     

2,2’-亚甲基-双(4,6-二叔丁基苯酚)制备及表征

以2,4-二叔丁基苯酚和甲醛为原料,通过乳液缩聚的方法合成2,2’-亚甲基-双(4,6-二叔丁基苯酚)。采用单因素实验设计方法,分别研究甲醛用量、甲醛加入方式、催化剂用量、乳化剂用量、反应时间、反应温度对产物理论转化率的影响,确定其最优的合成工艺条件为2,4-二叔丁基苯酚0.05 mol,去离子水50 mL,甲醛7mL,乳化剂0.2 g(0.000 87 mol),硫酸0.25 mL,温度70℃,氮气保护,强力搅拌作用,此时产率达98%、纯度达97%。通过红外吸收光谱、核磁共振谱、示差扫描量热分析和热失重分析等对合成产物进行结构和物性参数分析和测定。结果表明:该工艺条件下得到的产物为2,2’-亚甲基-双(4,6-二叔丁基苯酚),IR谱图上2 957、3532、1 394、1 362 cm-1处为其特征官能团吸收峰,1H-NMR或13C-NMR在3.979 6或29.042 5～34.775 1的化学位移峰表明,甲醛与酚成功缩合,实现桥联;通过DSC和TG测得,产物的熔点和分解温度分别为150℃和202.47℃,与目标产物一致。     

热塑性苯酚甲醛树脂的分子量、游离苯酚含量对胶料加工性能的影响

树脂补强体系下的橡胶硫化实际上是树脂网络和橡胶网络的形成以及相互穿插的过程,热塑性苯酚甲醛树脂的分子量以及游离酚含量势必会对树脂网络的形成产生影响,从而影响橡胶的硫化以及胶料的加工过程。本文就是制备出不同分子量的热塑性苯酚甲醛树脂以及不同游离酚含量的热塑性苯酚甲醛树脂,测试含有这些树脂胶料的加工性能,得出结论,并且用这些结论分析市售的热塑性苯酚甲醛树脂对胶料加工性能的影响。     

正交试验优化热塑性酚醛树脂合成工艺

以甲醛、苯酚为原料,草酸为催化剂合成热塑性酚醛树脂.通过正交试验进行优化,确定了其合成的最佳工艺方案:催化剂草酸用量2.0%(基于苯酚质量),n(甲醛):n(苯酚)=0.82:1,反应时间3.5 h.试验的方差结果表明:甲醛和苯酚的量比是反应的主要影响因素.     

酚醛环氧防腐涂料用固化体系研究进展

综述了近年来国内外酚醛环氧防腐涂料用固化体系的研究现状和进展,包括苯酚-甲醛、双酚A-甲醛树脂和腰果酚-苯酚-甲醛树脂等酚醛树脂固化体系,苯酚-甲醛、双酚A-甲醛改性胺和腰果酚缩醛胺固化体系及其他固化体系。认为腰果酚改性胺固化剂是一种性能优异的环氧树脂固化剂,它对开发新型高性能、多用途、低成本和环保型的重防腐环氧树脂涂料固化技术提供了新思路。     

Phenol-formaldehyde impregnant characterization by infrared spectroscopy and differential scanning calorimetry

A series of resol-type phenol-formaldehyde resins was investigated by infrared spectroscopy and differential scanning calorimetry. The molar ratio of phenol to formaldehyde was determined from the absorbance ratio D₁₀₁₀/D₁₆₁₀. Differences between the reactivities of resins were confirmed by the molar phenol to formaldehyde ratio, heat of reaction and gelation time.     

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.     

石油化工管道阻燃保温材料的研制

介绍酚醛泡沫塑料的生产工艺和性能，讨论酚／醛比、催化剂对树脂性能的影响以及树脂固含量、固化剂、密度对泡沫塑料性能的影响。结果表明，酚／醛摩尔比为1：1．5－2．0、采用复合催化剂时，树脂性能较好；固含量较高时，泡沫塑料性能好；泡沫塑料密度增大，强度提高，但保温性能变差。所研制的酚醛泡沫塑料耐燃、少烟、无毒，可用作石油化工管道保温材料。     

Determination of specific heat of phenol formaldehyde resol resins by differential scanning calorimetry

The specific heat, Cp, was determined by DSC on a series of resol-type phenol formaldehyde resins with varying phenol formaldehyde molar ratio. The extrapolated Cp values at 25°C vary between 1.181-1.206 kJ · kg^?1 K^?1 and the dCp/dT ratio was found to be 0.0042kJ · kg^?1K^?2 in the temperature range of 70–125°C.     

腰果酚制备可发性酚醛树脂的合成工艺研究

以苯酚、腰果酚、甲醛为原料,NaOH为催化剂,乙二醇为助剂,合成了可发性酚醛树脂,通过粘度,固含量,韧性测试研究了原料的配比,腰果酚替代苯酚的比例,催化剂用量,反应时间,反应温度及乙二醇用量对合成树脂性能的影响并通过IR,TG分析对树脂结构及耐热性进行了表征。结果表明,适宜的反应条件为:F/P比(甲醛与总酚物质的量比值)1.6,腰果酚替代量20%,催化剂用量1%,反应时间3 h,反应温度80℃,乙二醇质量分数10%～15%。以腰果酚制备的CPF树脂耐热性变化不明显,拉伸强度为22.34 MPa,断裂伸长率3.08%,冲击强度3.56 kJ/m2,较PF树脂有很大提高。     

Characterization of substituted phenol–formaldehyde resins using solid-state carbon-13 NMR

Crosslinked substituted phenol–formaldehyde resins were synthesized from cashew nut shell liquid, 3-n-pentadecylphenol and phenol with formaldehyde. The resulting resins were crosslinked and investigated using carbon-13 NMR in the solid state using cross-polarization, magic angle spinning, and dipolar decoupling. Comparisons were made between the spectra of pure phenol–formaldehyde resins and it was shown possible to distinguish between the resins. It was also shown that the proton-dephased spectrum gave better spectral resolution for the substituted compounds. In addition, the solids carbon-13 technique verified that the degradation of the substituted phenolic resins occurs first with the degradation of the side chain in agreement with suggestions from earlier work.     

Modelling of resole type phenol formaldehyde polymerization

The kinetics of polymerization of phenol formaldehyde has been modelled to account for the formation of highly-branched resole molecules. The conversions of phenol and formaldehyde, number-average chain length, degree of branching and the concentrations of internal and external ortho and para-H atoms are obtained as functions of time, for several values of the various rate constants and the initial phenol to formaldehyde ratios. The conversions of phenol and formaldehyde are found to be most sensitive to the rate constant associated with the reaction between the external para-H atom with ---CH₂OH groups. The condensation between two ---CH₂OH groups prevents complete depletion of formaldehyde and leads to highly-branched, high molecular weight final products at large reaction times. Our studies show that at low values of the initial phenol to formaldehyde ratio, small amounts of lightly-branched, low molecular weight polymer with a high degree of substitution by ---CH₂OH groups is obtained. At some intermediate initial phenol to formaldehyde ratio, highly-branched, high molecular weight product is obtained and at high values of this feed ratio, larger amounts of lightly-branched, lower average molecular-weight product is obtained.