Kinetic parameters of thermal degradation of polyethylene glycol‐toughened novolac‐type phenolic resin

The miscibility and thermal degradation of poly(ethylene glycol) (PEG)‐toughened novolac‐type phenolic resin were investigated. Differential scanning calorimetry (DSC) results confirmed that the phenolic resin/PEG blend was blended completely. Infrared spectra show that hydrogen bonding existed in the blends. Thermal degradation of PEG blended with novolac‐type phenolic resin was studied utilizing a dynamic thermogravimetric technique in a flowing nitrogen atmosphere at several heating rates (i.e., 5, 10, 20, 40°C/min). Thermal degradation of phenolic resin/PEG blends takes place in multiple steps. The thermal behavior and the thermal stability affected the thermal degradation, which coincided with the data from the thermal degradation of novolac‐type phenolic resin/PEG blends by thermogravimetric analysis (TGA). © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 188–196, 2001     

Mechanical properties,thermal stability,and flame retardance of novolac‐type phenolic resin blended with poly(dimethylsiloxaneadipamide)

Mechanical properties (flexural strength, flexural modulus, and notched Izod impact strength), thermal stability, and flame retardance of poly(dimethylsiloxane adipamide) (PDMSA)‐toughened novolac type phenolic resin were investigated. Mechanical properties of modified novolac‐type phenolic resin increase with PDMSA contents, because the soft segment of PDMSA absorbs the loads in the network of brittle novolac‐type phenolic resins. TGA results show that the thermal degradation temperatures are higher than 400°C, and the temperature of 10% weight loss increases with increasing the PDMSA content. The char yield increases with novolac‐type phenolic resin content. The morphologies of the fracture surface of the modified novolac‐type phenolic resin were investigated by scanning electron microscopy (SEM). Morphological results agree with those from mechanical properties of the modified novolac‐type phenolic resin. The modified novolac‐type phenolic resin also shows excellent flame retardance that is UL‐94, V‐1, and the limited oxygen index is higher than 35. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 79: 631–637, 2001     

Epoxidized phenolic novolac: A novel modifier for unsaturated polyester resin

Unsaturated polyester resins (UPRs) are used widely in the fiber‐reinforced plastics (FRPs) industry. These resins have the disadvantages of brittleness and poor resistance to crack propagation. In this study, hybrid polymer networks (HPNs) based on UPR and epoxidized phenolic novolacs (EPNs) were prepared by reactive blending. A HPN is composed of a backbone polymer containing two types of reactive groups that can take part in crosslinking reactions via different mechanisms. EPNs were prepared by glycidylation of novolacs using epichlorohydrin. The novolacs had varying phenol: formaldehyde ratios. Blends of unsaturated polyester with EPN were then prepared. The physical properties of the cured blends were compared with those of the control resin. EPN shows good miscibility and compatibility with the resin and improves the toughness and impact resistance substantially. Considerable enhancement of tensile strength is also noticed at about 5% by weight of epoxidized novolac resin. TGA, DMA, and DSC were used to study the thermal properties of the toughened resin and the fracture behavior was studied using SEM. The blends are also found to have better thermal stability. Blending with EPN can be a useful and cost‐effective technique for modification of UPR. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 457–465, 2006     

Properties of epoxy resin cured by phenol novolac/4-hydroxyphenylmaleimide polymer blend hardeners

Phenol novolac/4-hydroxyphenylmaleimide (HPMI) homopolymer (PHPMI) blends or phenol novolac/HPMI-styrene copolymer (HPMI-St) blends were used as the hardener of epoxy resins. Curing behaviour of the above systems and thermal and mechanical properties of the cured epoxy resins were studied. It was not necessary to use a curing accelerator for this system because PHPMI or HPMI-St had an accelerating effect on the curing reaction. Curing behaviour was investigated by measurement of gelation time(JIS K 6910) and differential scanning calorimetry thermogram (JIS K 7122). Test pieces made from neat resins and from reinforced resins with glass fibre or fused silica were evaluated in terms of thermal and mechanical properties, respectively. It was found that the heat resistance and the mechanical properties improved with increase of PHPMI or HPMI-St content in the hardener.     

Processability and properties of phenoxy resin toughened phenolic resin composites

A novel method has been developed to toughen phenolic resin using phenoxy resin. Phenoxy resin was dissolved in phenol to form a glutinous mixture at 110°C, and an acid catalyst (p-toluene sulfonic acid, PTSA) was utilized to reduce the viscosity of mixture. The mixture was blended with resole-type phenolic resin. IR spectra confirmed that the amount and strength of hydrogen bonds increased with PTSA content, and the viscosity decreased with PTSA content in the polymer blends. The wet-out of glass fiber by modified resin was improved. The flexural and notched Izod impact strength of the polymer-blend composites increased significantly. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 63: 911–917, 1997     

酚醛在丙烯酸树脂防火改性中的应用

以酚醛树脂为主防火剂、胺类为协效剂,研究了其种类、用量对丙烯酸树脂防火性能的影响,采用锥形量热仪和热重分析仪对酚醛改性丙烯酸树脂的燃烧性能和热稳定性进行了测试,并对燃烧后的炭层结构进行了电镜分析。结果表明,硼酚醛树脂能显著提高丙烯酸树脂的防火性能,硅酸铝、六次甲基四胺具有有良好的协效作用;当丙烯酸树脂与硼酚醛树脂质量比为50:50,硅酸铝质量分数为7%,六次甲基四胺为2%时,改性树脂耐燃时间达到39min,点燃时间(TTI)及热释放速率峰值出现时间明显延长,热释放速率明显降低,800℃时残炭率为45%,热稳定性明显提高,燃烧烧后形成了表面为致密网状、断面为微细泡孔状的炭层结构,防火性能提高。     

Morphology transition of bismaleimide‐modified novolac resin

The bismaleimide (BMI)‐modified novolac resin was synthesized by allylation of the novolac resin and its “Ene” reaction with BMI. The reactions were monitored by Fourier transform infrared analysis (FTIR). The morphology of the BMI‐modified novolac resin changed with degree of allylation (i.e., the amount of BMI used). On the basis of the studies done by dynamical mechanical analysis (DMA), differential scanning calorimetry (DSC), and field emission scanning electron microscopy (FE‐SEM), it was found that when the degree of allylation increased from 48 to 59%, the resin changed from a single‐phase structure to a two‐phase structure. From the research by thermogravimetric analysis (TGA) and DMA, it was found that the higher allyl‐content (when > 48%) caused a decrease of the thermal properties and mechanical properties of the resultant resin. The BMI‐modified allyl novolac resin with 48% degree of allylation has the best thermal properties and the highest dynamic modulus in the current research. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 76–83, 2006     

硼改性酚醛树脂的合成与性能

利用半成品酚醛树脂粉与硼酸直接混合,然后固化得到硼含量不同的硼酚醛树脂,并用傅里叶红外光谱、热重分析和冲击试验等方法对其性能进行了分析。红外分析结果表明,硼酸与酚醛树脂中的酚羟基、苄羟基发生了反应,生成了新的交联键。热分析结果发现,在酚醛树脂中加入硼酸能提高树脂的耐热性,当硼酸加入量为10%时达到最高值。硼酚醛树脂的冲击强度先随硼酸加入量的增大而增加,在5%时达到最大值,然后下降。     

双酚A型苯并恶嗪/酚醛体系固化物的性能研究

将双酚A型苯并恶嗪(BOZ-a)和线形酚醛树脂按照不同的配比进行共混固化,制备了浇铸体(BPx,x表示线形酚醛在共混树脂中的质量分数)。采用力学性能,吸水性测试,动态热机械分析和热重分析研究了酚醛树脂含量对浇注体性能的影响。结果表明,随着共混体系中酚醛树脂含量的增加,浇铸体弯曲强度呈下降趋势,玻璃化转变温度及交联密度也逐渐降低,但弯曲模量、初始储能模量、硬度和热稳定性均呈先上升后下降的趋势,而吸水率呈先减小后增加的趋势。BP20体系综合性能优良,初始模量最大,达到7.384 GPa,玻璃化转变温度为168℃,7 d吸水率为0.116%,5%热失重温度为285℃。     

超支化聚酰胺酯增韧增强环氧树脂的性能研究

以四氢甲基苯酐(MeTHPA)为固化剂,超支化聚酰胺酯(HBP)为增韧剂,制备了HBP/MeTHPA/环氧树脂(EP)固化体系。采用红外光谱(FT-IR)对HBP/MeTHPA/EP复合体系的固化机理进行了研究,并讨论了不同含量的HBP对固化体系热力学性能的影响。实验结果表明,HBP的加入会促进体系的固化反应;当w(HBP)=10%时力学性能最佳,冲击强度和拉伸强度分别增加了142.71%和34.44%,而玻璃化转变温度(Tg)有所下降,储能模量在玻璃态时均明显提高。     

Synthesis and properties of nano carboxylic acrylonitrile butadiene rubber latex toughened phenolic resin

Nano carboxylic acrylonitrile butadiene rubber latex‐toughened‐phenolic resins (XNBRL‐PF) were prepared by in situ polymerization in this work. The influence of nano XNBRL on the microstructure and physical properties of modified PF resin was investigated. Impact test testified that the impact strength of XNBRL‐PF was remarkably improved compared to pure PF and as the content of XNBRL increased to 10 wt %, the impact strength of the XNBRL‐PF kept increasing. Scanning electron microscope analysis of the fracture surface of the XNBRL‐PF indicated that the XNBRL were uniformly dispersed in the PF matrix, with diameters ranging from 200 to 400 nm. The results of Fourier transform infrared spectroscopy proved that chemical reaction occurred between XNBRL and PF matrix, which can greatly improve the interface interaction between rubber particles and PF matrix. Thermogravimetric analysis test showed that the incorporation of XNBRL can improve the thermostability of PF at low temperatures. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

新型含磷酚醛树脂的合成与性能

通过亚膦酸酯与碳碳双键之间的亲电加成反应,合成了一种新型的含磷马来酰亚胺酚醛树脂。采用红外光谱(FTIR)和元素分析法对聚合物的结构进行了表征。并用此含磷酚醛树脂作为环氧树脂的固化剂制得了一含磷氮的环氧固化物。采用热分析法、极限氧指数法对相应环氧固化物的耐热性能和阻燃性能进行了表征。研究结果表明:以该含磷聚合物作为环氧树脂的固化剂,对稳定固化物骨架碳的结构和交联成炭能力的提高起到了增强作用;环氧固化物具有较高的玻璃化转变温度(145.4℃)和较高的热稳定性(T508℃),极限氧指数显示其具有较好的阻燃性能。     

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。     

New type of phenolic resin: Curing reaction of phenol‐novolac based benzoxazine with bisoxazoline or epoxy resin using latent curing agent and the properties of the cured resin

In this study, we aimed to reduce the cure time, and to lower the cure temperature of the benzoxazine compound. Therefore, curing reaction of benzoxazine with bisoxazoline or epoxy resin using the latent curing agent and the properties of the cured resins were investigated. The cure behavior of benzoxazine with bisoxazoline or epoxy resin using the latent curing agent was monitored by differential scanning calorimetry and measurements for storage modulus (G′). The properties of the cured resin were estimated by mechanical properties, electrical insulation, water resistance, heat resistance, and flame resistance. As a result, it was confirmed that by using the latent curing agent, cure time of benzoxazine and bisoxazoline or epoxy resin was reduced, and cure temperature was lowered. And it was found that the curing reaction using phenol‐novolac based benzoxazine (Na) as the benzoxazine compound could proceed more rapidly than that using bisphenol‐A based benzoxazine (Ba) as the benzoxazine compound. However, the cured resins from Ba and bisoxazoline or epoxy resin using the latent curing agent showed good heat resistance, flame resistance, and mechanical properties compared with those from Na and bisoxazoline or epoxy resin using the latent curing agent. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

双酚A型双邻苯二甲腈/酚醛树脂共混体系研究

双酚A型双邻苯二甲腈(BAPh)与酚醛树脂(novolac)通过熔融共混形成了预聚物(BAPh/novolac),经后续热处理制备了BAPh/novolac固化物。通过DSC,FTIR,TGA及流变性能测试研究了该共混体系的固化反应特性,固化物的热稳定性和热氧化稳定性。结果表明:该共混体系可以在无外加固化剂的条件下进行固化反应,固化物的玻璃化转变温度(Tg)达241℃。其固化物在空气和N2气氛中的起始分解温度为380～449℃,且在氮气下800℃残炭率达71%,表现出良好的热稳定性和热氧稳定性。     

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。     

一种高耐热酚醛树脂的合成及表征

合成了一种新型高耐热酚醛树脂,并对其结构和性能进行了分析。研究发现,这种高耐热酚醛树脂对金属有良好的粘接性能,通过增韧改性可以进一步提高粘接强度;通过TG/DTA热分析手段,对合成过程中催化剂的加入量进行定量研究发现,当催化剂为树脂质量的12.5%时,合成树脂的耐热性能达到最佳,其粘接性能也非常优良。而且,用红外吸收光谱对这种新型高耐热酚醛树脂进行了表征,并确定了树脂的基本结构。     

Molecular origin of unusual physical and mechanical properties in novel phenolic materials based on benzoxazine chemistry

The effect of temperature on hydrogen bonding was investigated by measuring the integrated infrared absorbance of various hydrogen-bonding modes as a function of temperature. It was found that conformationally preferred hydrogen- bonding modes maintain constant intensities over the wide temperature ranges studied for both polybenzoxazines and a novolac-type phenolic resin. In particular, the O— — —H— — —N hydrogen bond shows strong bonding that does not change over the temperature range. On the other hand, statistically distributed hydrogen bonding is more sensitive to the temperature change and its infrared intensities start decreasing around the β-transition of polybenzoxazines. The unusual physical and mechanical properties of polybenzoxazines, including volumetric expansion upon polymerization, high moduli, and high glass transition temperatures, are explained based on the complex hydrogen bonding. © 1998 John Wiley & Sons, Inc. J. Appl. Polym. Sci. 70: 1299–1306, 1998     

Synthesis of a novel epoxy resin containing pyrene moiety and thermal properties of its cured polymer with phenol novolac

A new epoxy resin containing the pyrene moiety in the backbone (3) was synthesized and confirmed by gel permeation chromatography and field‐desorption mass spectroscopy and infrared spectroscopy. In addition, to evaluate the influence of the pyrene moiety on the structure, epoxy resins having an anthrylene moiety (5) and having a phenylene moiety (7) were synthesized. The cured polymer obtained through the curing reaction between 3 and phenol novolac was used for making a comparison of its thermal properties with those obtained from 5, 7, and bisphenol‐A (4,4′‐isopropylidenediphenyl)‐type epoxy resin (Bis‐EA). The cured polymer obtained from 3 showed a higher glass transition temperature, lower coefficient of linear thermal expansion, lower moisture absorption, and markedly higher anaerobic char yield at 700°C of 37.6 wt %, which might be attributed to the higher aromaticity of 3 containing the pyrene moiety. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 75: 528–535, 2000     

Phenol novolac/poly(4- hydroxyphenylmaleimide) blend hardeners for DGEBA-type epoxy resin

Phenol novolac/poly (4-hydroxyphenylmaleimide) (PHPMI) blends were used as an epoxy resin hardener. The curing behavior of the above system and the thermal and mechanical properties of the cured epoxy resin were studied. It was not necessary to use a curing accelerator for this system, because PHPMI caused acceleration of the curing reaction. The curing mechanism of this system was investigated by using model compounds. Test pieces from the neat resins and the glass fiber reinforced resins were evaluated in terms of thermal and mechanical properties, respectively. It was found that heat resistance and mechanical properties were improved by increasing the amount of PHPMI in the hardener.