Polymerization studies of creosote bush (Larrea tridentata) phenolic resin with formaldehyde

About 25% of the surface area of Mexico is covered by the shrub Larrea tridentata, also known as creosote bush. Therefore, an intense study of the shrub as a source of industrial raw materials was started. Presently, we have studied the polymerization of the phenolic resin of Larrea with formaldehyde. This polymerization has been carried out in bulk and in aqueous suspension with acid catalysts such as oxalic and hydrochloric acids. The molar ratio of Larrea resin/formaldehyde was 1/1, 1/3, and 1/4 at different reaction times. Larrea resin and the formaldehyde condensation products were characterized by gel permeation chromatography (GPC), proton nuclear magnetic resonance (NMR), and vapor pressure osmometry (VPO).     

低游离甲醛可发性液态酚醛树脂的制备

以苯酚和多聚甲醛为原料合成可发性液态酚醛树脂,考察了催化剂、甲醛与苯酚摩尔比、反应温度、反应时间和甲醛捕捉剂对酚醛树脂中游离甲醛含量及酚醛树脂黏度的影响。结果表明:以复合催化剂作为催化剂,用量为苯酚质量的5%,采用逐步升温工艺,在60~70℃条件下反应3.0 h,80℃条件下反应2.5 h,添加盐酸羟胺与尿素组成的复合甲醛捕捉剂于80℃继续反应0.5 h,得到的可发性液态酚醛树脂的游离甲醛质量分数为0.12%,黏度为3.97 Pa·s。     

Phytotoxic properties of nordihydroguaiaretic acid,a lignan fromLarrea tridentata (Creosote bush)

The phytotoxic properties of nordihydroguaiaretic acid (NDGA) isolated from creosote bush,Larrea tridentata (Zygophyllaceae), were examined. NDGA dramatically reduces the seedling root growth of barnyard grass, green foxtail, perennial ryegrass, annual ryegrass, red millet, lambsquarter, lettuce, and alfalfa, and reduces the hypocotyl growth of lettuce and green foxtail. It has no effect on the germination of lettuce seeds. NDGA almost certainly contributes to the observed allelopathic nature of creosote bush.Work performed during sabbatical year leave at Western Regional Research Center.     

Creosote Bush (Larrea tridentata) Resin Increases Water Demands and Reduces Energy Availability in Desert Woodrats (Neotoma lepida)

Although many plant secondary compounds are known to have serious consequences for herbivores, the costs of processing them are generally unknown. Two potential costs of ingestion and detoxification of secondary compounds are elevation of the minimum drinking water requirement and excretion of energetically expensive metabolites (i.e., glucuronides) in the urine. To address these impacts, we studied the costs of ingestion of resin from creosote bush (Larrea tridentata) on desert woodrats (Neotoma lepida). The following hypotheses were tested: ingestion of creosote resin by woodrats (1) increases minimum water requirement and (2) reduces energy available by increasing fecal and urinary energy losses. We tested the first hypothesis, by measuring the minimum water requirement of woodrats fed a control diet with and without creosote resin. Drinking water was given in decreasing amounts until woodrats could no longer maintain constant body mass. In two separate experiments, the minimum drinking water requirement of woodrats fed resin was higher than that of controls by 18-30% (about 1-1.7 ml/d). We tested several potential mechanisms of increased water loss associated with the increase in water requirement. The rate of fecal water loss was higher in woodrats consuming resin. Neither urinary water nor evaporative water loss was affected by ingestion of resin. Hypothesis 2 was tested by measuring energy fluxes of woodrats consuming control vs. resin-treated diets. Woodrats on a resin diet had higher urinary energy losses and, thus, metabolized a lower proportion of the dietary energy than did woodrats on control diet. Fecal energy excretion was not affected by resin. The excretion of glucuronic acid represented almost half of the energy lost as a consequence of resin ingestion. The increased water requirement and energy losses of woodrats consuming a diet with resin could have notable ecological consequences.     

低甲醛排放脲醛树脂胶的制备及应用

尿素与甲醛的物质的量比1∶1,甲醛分2次加入,尿素分4次加入,增强剂为三聚氰胺,占尿素总量的4%。甲醛分2次加入的目的是使尿素与甲醛的反应动力学中生成的次甲基脲与二羟甲基脲处于最大值。用此工艺制备的UF树脂制成的人造板性能远高于国家标准及国际标准,板材的甲醛释放量达到F四星级标准。     

Regeneration and utilization of waste phenolic formaldehyde resin: A performance investigation

Recycled thermosetting phenolic formaldehyde (RPF) resins were pulverized to micron-sized powders and successfully reused as an effective component by reactive-injecting with neat phenolic formaldehyde (PF) and/or trioxymethylene (TOX) to prepare regenerated phenolic formaldehyde (i.e., and ). Tensile strength (σ_f), impact strength (I_s), and density (ρ) of and specimens were reduced as RPF concentrations or average particle sizes increased. It is worth emphasizing that σ_f, I_s, and ρ of each reaction-injected series having a fixed RPF concentration and average particle size improved to a maximum value, as TOX concentrations reached a corresponding optimal value. This is the first investigation to report that σ_f and I_s of proper regenerated PF/RPF/TOX specimens using ≦20 wt % RPF waste were ≥ 95% of those of the virgin reaction-injected PF. Possible reasons accounting for these improved mechanical properties were proposed based on results from their Fourier transform infrared analysis (FTIR). © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47445.     

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     

HDI-BPA酚醛树脂的合成及应用性能

以双酚A(BPA)酚醛树脂和六亚甲基二异氰酸酯(HDI)为原料,在二月桂酸二丁基锡(DBTDL)催化作用下合成了HDI-BPA酚醛树脂。采用FTIR、~1HNMR、GPC、有机元素分析等对HDI-BPA酚醛树脂的化学结构和相对分子质量进行了表征,结果表明目标产物成功制备,其M_w为3376。探讨了反应温度、反应时间、物料配比、催化剂用量等因素对目标产物中异氰酸酯基质量分数及接枝率的影响。通过建立异氰酸酯基质量分数和接枝率的二次回归方程,使用响应面分析法中的Box-Behnken Design(BBD)对HDI-BPA酚醛树脂的合成工艺进行了优化,最佳工艺条件为:反应温度32℃、反应时间为55 min、m(BPA酚醛树脂)∶m(HDI)∶m(DBTDL)=0.2101∶1∶0.0025。在此条件下,合成产物中异氰酸酯基质量分数为25.51%,接枝率为48.929%。最后,在HDI-BPA酚醛树脂中加入E-51固化剂,制备出HDI-BPA酚醛树脂胶黏剂,其最大粘结力达283.69 N,相对于BPA酚醛树脂胶黏剂的性能提升了3.7倍,表明HDI的加入显著提高了BPA酚醛树脂对低极性皮革基材的粘结性能。同时,HDI-BPA酚醛树脂胶黏剂的接触角为93.5°,表现出较好的疏水和耐水性能。     

聚乙烯醇缩甲乙醛改性酚醛树脂的热稳定性研究

以苯酚、甲醛、聚乙烯醇缩甲乙醛为原料,合成了改性酚醛树脂,通过红外光谱表征了聚乙烯醇缩甲乙醛改性酚醛树脂的结构,并通过TGA分析了聚乙烯醇缩甲乙醛改性酚醛树脂的热性能。结果表明:聚乙烯醇缩甲乙醛改性的酚醛树脂初始热分解温度为271.8℃,796℃时失重76.43%,与聚乙烯醇缩丁醛改性的酚醛树脂相比,由于缩短了酚醛树脂的碳链,热稳定性增加。     

热固性钼酚醛树脂的表征及其应用

为了提高普通热固性酚醛树脂结合耐火材料的中温强度,采用IR和TG-DTA等手段分析了热固性钼酚醛树脂的结构和热性能,然后以热固性钼酚醛树脂作为结合剂制成铝碳砖试样,检测了铝碳砖试样的耐压强度、显气孔率和体积密度。结果表明:钼酚醛树脂是通过钼酸与酚醇中的羟甲基发生酯化反应,使钼以化学键的形式键合于酚醛树脂分子主链中而合成的;热固性钼酚醛树脂在质量损失率、热分解温度和树脂碳氧化温度等方面都比普通热固性酚醛树脂的有所改善,TG曲线在整个温度范围内的下降趋势也较平缓;热固性钼酚醛树脂结合的铝碳砖试样在200℃、500℃和600℃处理后的耐压强度分别比普通热固性酚醛树脂结合的提高了约23.1%、51.2%和70.3%,显气孔率也有所下降,体积密度有所提高。     

BPS-BPA酚醛环氧树脂的合成及其应用性能

以双酚A环氧树脂(BPA酚醛树脂)和4,4-二羟基二苯砜(BPS)为原料,环氧氯丙烷为桥连剂,在四丁基溴化铵(TBAB)的催化作用下合成了BPS-BPA酚醛环氧树脂(目标产物)。采用FTIR、1HNMR、GPC、EDS等对产物的化学结构及分子量进行测试。结果表明,产物Mw为4355且表现出较好的耐温性能,此外还探讨了反应温度、反应时间、物料配比、Na OH用量等因素对目标产物环氧值的影响。利用正交实验设计获得了目标产物的最佳工艺条件为:反应温度110℃,反应时间2.5 h,m(BPA酚醛树脂)∶m(BPS)=1∶0.9,Na OH用量1.98 g,在该条件下合成产物的环氧值为0.718。最后向目标产物中加入聚酰胺树脂固化剂,得到的胶粘剂具有优良的粘结性能,其最大粘结力达100.66 N,层间结合强度0.788 N/m,对低极性聚丙烯材料具有很好的附着性能。     

秸秆乙醇副产物酚醛树脂的制备与应用

以秸秆乙醇副产物、苯酚、甲醛为原料,NaOH为催化剂,通过逐步共聚制备了秸秆乙醇副产物改性酚醛树脂胶粘剂,并进行了中试放大试验和人造板生产试验。通过工艺优化发现,秸秆乙醇副产物最高可替代50%质量的苯酚,且不影响酚醛树脂胶粘剂的性能,其游离甲醛含量0.22%;制备的桉杨三层胶合板100℃水煮3 h,粘接强度为0.98 MPa,达到国家Ⅰ类板要求;甲醛释放量为0.23 mg/L,达到E0级。     

含有互穿网络结构的丁腈橡胶改性环氧/酚醛胶粘剂的合成及其应用

合成了一种含有互穿网络结构的丁腈橡胶(BN)改性环氧/酚醛胶粘剂。通过扫描电镜(SEM)分析, 证明了此胶片具有互穿网络结构。同时对胶粘剂进行了差热分析(DTA),并考察了其粘结性能以及贮存性能。最后将其成功地应用到一种厚铜箔(0.4～0.5mm)环氧玻璃布层压板上,得到的覆铜板样品具有剥离强度高、平整度好、电性能优良等特点。     

Coating properties of alkyd-ketonic (cyclohexanone formaldehyde) resin blends

The present article describes the preparation and coating properties of long oil-length alkyd and ketonic (cyclohexanone formaldehyde) resin blends. A unique solvent system, which shows a one-phase clear solution and a clear coat of the binder system, was used. The scope of the article is to produce a better combination of properties than those of the individual components. It has been observed that, when a 30% concentration of ketonic resin was blended with the alkyd resin, a significant improvement in adhesion, hardness, gloss, storage stability, acid resistance, and drying time was achieved over that of the alkyd resin alone.     

Study on modified phenolic resin. I. Modification with homopolymer prepared from p-hydroxyphenylmaleimide

We studied the improvement of heat resistance and mechanical properties of phenolic resin modified with polymers prepared from p-hydroxyphenylmaleimide (HPMI). Homopolymers of HPMI and copolymers of HPMI with some vinyl monomers were synthesized and M_n T_g and thermal decomposition temperature of them were measured by GPC, DSC, and TG, respectively. The miscibility of homopolymer with novolac was examined by DSC. It was found that the homopolymer had good heat resistance and good miscibility with novolac. Molding compounds were prepared by hot roll-kneading the mixtures of novolac, the homopolymer, hexamethylenetetramine, and glass fiber. It was found that molded test pieces had good heat resistance.     

Preparation and characterization of novolac type phenolic resin blended with poly(dimethylsiloxane adipamide)

Phenolic resin/poly(dimethylsiloxane adipamide) (PDMSA) blends, which have been prepared, show miscibility due to intermolecular H‐bonding existing between phenolic resin and the PDMSA. The specific H‐bonding of novolac type phenolic/PDMSA blends was characterized by means of glass transition temperature behavior and Fourier Transform Infrared Spectroscopy (FTIR). The strength of intermolecular H‐bonding within the phenolic blend is a function of the H‐bonded group of the PDMSA modifier and corresponds to the deviation glass transition temperature (ΔT_g). Phenolic/PDMSA blends were completely miscible, as confirmed by the T_g study. The FTIR result is in good agreement with the inference from T_g behavior. The char yield of phenolic/PDMSA corresponds to the phenolic resin content. The molecular mobility of phenolic/PDMSA blends increases with PDMSA content in the phenolic‐rich region. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 984–992, 2002     

The study of hydrogen bonding and miscibility in poly(vinylpyridines) with phenolic resin

The hydrogen bonding and miscibility behaviors of poly(2-vinylpyridine) (P2VP) or poly(4-vinylpyridine) (P4VP) with phenolic resin were investigated by differential scanning calorimetry and Fourier transform infrared spectroscopy (FTIR). These blends have a single glass transition over the entire composition range indicating that these blends are able to form a miscible phase due to the formation of inter-molecular hydrogen bonding between hydroxyl of phenolic and pyridine ring of poly(vinylpyridines). Furthermore, FTIR studies on the hydrogen-bonding interaction between the hydroxyl group of phenolic and pyridine ring of poly(vinylpyridines) at various compositions and temperatures indicate that the greater inter-association for P4VP than P2VP due to the steric hindrance effect on specific interaction between these two polymers. Finally, inter-association equilibrium constants of phenolic/P2VP and phenolic/P4VP blends were determined by model compounds.     

Miscibility and hydrogen bonding in blends of poly(vinyl acetate) with phenolic resin

The miscibility of phenolic resin and poly(vinyl acetate) (PVAc) blends was investigated by differential scanning calorimeter (DSC), Fourier transform infrared spectroscopy (FT-IR) and solid state ¹³C nuclear magnetic resonance (NMR). This blend displays single glass transition temperature (T_g) over entire compositions indicating that this blend system is miscible in the amorphous phase due to the formation of hydrogen bonding between hydroxyl groups of phenolic resin and carbonyl groups of PVAc. Quantitative measurements on fraction of hydrogen-bonded carbonyl group using both ¹³C solid-state NMR and FT-IR analyses result in good agreement between these two spectroscopic techniques. According to the proton spin-lattice relaxation time in the rotating frame (T_1ρ^H), the phenolic/PVAc blend is intimately mixed on a scale less than 2-3 nm. Furthermore, the inter-association equilibrium constant and its related enthalpy of phenolic/PVAc blends were determined as a function of temperatures by infrared spectra based on the Painter-Coleman association model.     

Plasticized/graphite reinforced phenolic resin composites and their application potential

Plasticized graphite (PG)/phenolic resin composites are candidates for positive temperature coefficient resistivity (PTCρ) thermistors, which are used for self‐recoverable elements that provide protection from overcurrents, gasoline sensors, and electrostatic charge and electromagnetic wave shielding in many kinds of electrical devices. The morphology and network structure of PG/phenolic resin composites have been characterized with scanning electron microscopy and with measurements of the crosslinking density, bound resin content, degree of crystallinity, viscosity, surface energy, thermal conductivity, enthalpy, and glass‐transition temperature. In addition, mechanical properties such as the tensile strength, Young's modulus, Shore A hardness, and elongation at break for resins filled with PG have been studied. The electrical properties of the composites have been measured to relate the PG volume fraction to the electrical conductivity. A large PTCρ value has been observed for all samples. The mechanism of the PTCρ effect in the materials is related to the thermal expansion and highest barrier energy of the composites. Switching behaviors of the current and voltage for all samples have been observed. The applicability of PG/phenolic resin composites for temperature controllers and gasoline gas sensors has been examined. The antistatic charge dissipation and dielectric constant as functions of the PG content have been studied. Finally, the experimental electromagnetic interference of the PG/phenolic composites has been investigated in the frequency range of 1–15 GHz and compared with a theoretical model. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 697–709, 2007     

酚醛树脂的研究现状、工业化应用需求及展望

综述了酚醛树脂胶粘剂的主要合成工艺及最新研究进展、国内主要酚醛树脂企业产能分布,分析了国内酚醛树脂的消费情况、进出口量及价格走势。同时对国内现有酚醛树脂胶粘剂在胶合板中的应用市场进行了调研与讨论,为更好地研制符合国家发展需求、品质和经济上有竞争力的酚醛树脂胶粘剂提供参考。