Study on modified phenolic resin. II. Modification with p-hydroxyphenylmaleimide/styrene copolymer

The improvement of heat resistance and mechanical properties of phenolic resin was examined with the blend of novolac and copolymers prepared from p-hydroxyphenylmaleimide (HPMI) and styrene. Copolymers of HPMI and styrene with various molecular weights were synthesized. Glass transition (T_g) and thermal decomposition temperatures of the copolymers were measured by differential scanning calorimetry (DSC) and thermogravimetry (TG), respectively. The miscibility of the copolymers with novolac was examined by DSC. It was found that the copolymers had a good heat resistance and a good miscibility with novolac. Molding compounds were prepared by hot roll-kneading of mixtures that involved novolac, copolymer, hexamethylenetetramine (hexamine), and glass fiber. It was found that the test pieces prepared by transfer molding from the molding compounds showed a good heat resistance and better mechanical properties than phenolic resin modified with HPMI homopolymer.     

Study on modified phenolic resin. III. Modification with p-hydroxyphenylmaleimide/acrylic ester copolymer

The improvement of toughness and heat resistance of phenolic resin was examined by blend of novolac and copolymers prepared from p-hydroxyphenylmaleimide (HPMI) and acrylic ester. Copolymers of HPMI and acrylic esters, such as methyl acrylate, ethylacrylate, n-butylacrylate, or 2-ethylhexyl acrylate, were synthesized. Average molecular weights, glass transition temperatures (T_g) and thermal decomposition temperatures were measured. The miscibility of the copolymers with novolac was evaluated. It was found that these copolymers had higher average molecular weight and higher thermal decomposition temperature than those of novolac; they also had good miscibility with novolac. Molding compounds were prepared by hot roll-kneading of mixtures, which involved novolac, the copolymer, hexamethylenetetramine (hexamine), and glass fiber. Test pieces of the modified phenolic resins were prepared by transfer molding from the molding compounds. It was found that phenolic resin, modified with HPMI/ethylacrylate copolymer or HPMI/n-butylacrylate copolymer, which consisted of numerous units of acrylic ester, showed both good toughness and good heat resistance.     

煤焦油改性酚醛树脂研究

引入含有多环芳烃煤焦油组分来改性酚醛树脂,在反应釜中按一定比例加入苯酚、甲醛、氢氧化钠和煤焦油.在碱性催化剂作用下反应4～7 h,真空脱水,得到了煤焦油改性热固性酚醛树脂.对改性后树脂的固含量、残炭值测定和热失重-差热分析,结果表明煤焦油加入量为苯酚质量的15%时改性树脂具有较大的固含量和残炭值,耐热性也得到了显著提高.     

低压钡酚醛树脂改性苯并噁嗪树脂的研究

采用低压钡酚醛树脂(BPF)改性苯并噁嗪(BOZ-A)树脂,制备了一种新型树脂体系。通过DSC(差示扫描量热)法、TGA(热失重分析)法和凝胶试验探讨了共混树脂的基本性能。研究结果表明:随着BPF掺量的不断增加,BOZ-A树脂的凝胶时间明显缩短;共混树脂的热降解速率在300~500℃时相对较大,其残炭率为62%左右;当w(BPF)=20%(相对于共混树脂体系质量而言)时,共混树脂的表观活化能为58.01 k J/mol。     

蔗糖八乙酸酯改性酚醛树脂的研究

首次将蔗糖八乙酸酯(SOA)引入到酚醛树脂(PF)体系中,并采用傅里叶红外光谱(FT-IR)、差示扫描量热法(DSC)、热重分析(TGA)和扫描电镜(SEM)等对改性PF的性能进行了表征。结果表明:当w(SOA)≤9.1%时,PF的热分解温度和800℃时的残炭率都有所提高;加入SOA后,PF的固化温度提高,并且由一步固化转变为二步固化;SOA与PF具有良好的相容性,可以有效抑制树脂固化中产生的气泡,有利于降低材料的内部缺陷;当w(SOA)≈7%时,玻璃纤维增强SOA改性PF复合材料的冲击强度提高了9.5%。     

Studies on modified phenolic resin. Iv: Properties of phenolic resin modified with 4-hydroxyphenyl- maleimide/n-butylacrylate copolymers

Three 4-hydroxyphenylmaleimide/ n-butylacrylate (HPMI/n-BuA) copolymers with different monomer ratios were synthesized. Their average molecular weights, glass transition temperatures (T,_g), and thermal decomposition temperatures were measured. It was found that these copolymers had higher average molecular weights and higher thermal decomposition temperatures than novolac. Modified phenolic resins were prepared by transfer moulding from moulding compounds consisting of novolac, the copolymer, hexamethylenetetramine (hexamine), and glass fibre. Properties of the three kinds of modified phenolic resins were examined by flexural test, impact test, dynamic thermomechanometry, and observation of morphology. It was found that phenolic resin modified with HPMI/ n-BuA (1/3-6) copolymer and modified with HPMI/n-BuA (1/7-0) copolymer showed good toughness and good heat resistance. It was also found that the heat resistance of modified phenolic resins was improved by after-cure, but the mechanical properties were decreased by after-cure: similar behaviour was observed for unmodified phenolic resin.     

造纸废液改性酚醛树脂胶粘剂的研究

木质素是造纸工业废液中的主要成分,具有与酚醛树脂相似的结构,因此可以部分替代苯酚用于酚醛树脂的生产。采用造纸废液替代部分苯酚制备改性酚醛树脂胶粘剂,并将该胶粘剂用于全桦三层胶合板的压制。在改性胶粘剂合成过程中,采用二次缩聚法、强碱性催化剂分3批投入,并以投料量、投料温度和粘度为可变因素设计正交实验,分析各因素对胶合板的胶合强度及浸渍剥离率的影响。实验结果表明,当w(造纸废液)=10%、投料温度为50℃和投料粘度为25s时,所压制的胶合板能够达到GB/T 9 846.7-2004Ⅰ类板的标准要求,并使造纸废液的污染程度和成本明显降低。     

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。     

改性间苯二酚-甲醛树脂GLR-20的应用研究

试验研究改性间苯二酚-甲醛树脂GLR-20替代间苯二酚对NR胶料性能的影响,并与进口产品B-20-S进行对比。结果表明,以GLR-20或B-20-S替代间苯二酚用于间-甲-白粘合体系中,通过适当增大硫黄和促进剂用量,可以改善胶料的加工安全性,提高硫化胶的拉伸强度、撕裂强度和粘合性能;在相同条件下使用GLR-20或B-20-S,胶料的各项性能基本相当。     

硼酚醛树脂对环氧树脂的改性研究

在环氧树脂中加入BPF进行改性,按照不同配比将BPF/EP配成稳定、均一的试样。对试样的凝胶时间和环氧值进行了测定,并计算出不同配比试样的反应活化能,探讨了不同配比对凝胶时间和环氧值的影响。对不同配比固化试样的氧指数和冲击强度进行了测试,结果显示,BPF的加入能够明显改善环氧树脂的阻燃性能和冲击强度。当BPF的含量为40%(质量分数)时,固化物的氧指数为25.0。当BPF/EP固化比例为3∶7时,冲击强度最高,为40.3 k J/m²。     

Jute felt composite from lignin modified phenolic resin

Raw and dewaxed jute felt composites were prepared with resol and lignin modified phenol formaldehyde resin. Four different types of lignin modified resins were used by replacing phenol with lignin. The lignin modified resins were prepared from purified lignin obtained from paper industry waste black liquor. To investigate bonding between jute and resin, IR spectroscopy of jute felts and composites was carried out. The thermal stability of the composites was assessed by DSC and TGA. It was found that the lignin resin jute composite is thermally more stable than resol composite. XRD of jute felt and composite shows that the crystallinity of the jute fiber increases after composite preparation. The lignin resin composites were tested for water absorption and thickness swelling, and it was found that the results are comparable with those of resol jute composite. Composites prepared from lignin phenol formaldehyde resin with 50% phenol replacement has shown 75% tensile strength retention to that of pure resol jute composite.     

纳米颗粒改性酚醛树脂用于镁碳砖结合剂的研究

利用纳米粒子对镁碳砖生产用酚醛树脂粘合剂进行了改性。改性树脂常规指标符合镁碳砖结合剂的要求。FE-SEM照片可以看到球形和近球形的纳米颗粒,分散均匀且基本无团聚。制砖实验结果表明,以改性树脂为结合剂能有效地减小显气孔率,增大体积密度且明显提高砖的压缩强度。特别是以TEOS(正硅酸乙酯)和纳米炭黑改性酚醛树脂为结合剂的镁碳砖,经200℃/12h热处理后的常温压缩强度分别提高了38.5%和30.4%,达到了43.94MPa和41.35MPa。砖坯的理化性能检测表明,随处理温度的升高,压缩强度和体积密度越来越小,显气孔率越来越大,200~1100℃各指标变化显著,1100~1550℃各指标没有显著变化,但呈变差趋势。     

硼酚醛树脂对环氧树脂的改性研究

在环氧树脂中加入BPF进行改性,按照不同配比将BPF/EP配成稳定、均一的试样。对试样的凝胶时间和环氧值进行了测定,并计算出不同配比试样的反应活化能,探讨了不同配比对凝胶时间和环氧值的影响。对不同配比固化试样的氧指数和冲击强度进行了测试,结果显示,BPF的加入能够明显改善环氧树脂的阻燃性能和冲击强度。当BPF的含量为40%(质量分数)时,固化物的氧指数为25.0。当BPF/EP固化比例为3∶7时,冲击强度最高,为40.3 k J/m~2。     

酚醛树脂改性研究新进展

从天然植物油和合成有机物2方面阐述改性酚醛树脂的新进展,重点讨论了桐油、聚苯醚、双噁唑啉及苯并噁嗪改性酚醛树脂的情况,简介了本实验室自制热塑性酚醛树脂(Novolak),并以苯噁嗪对Novolak进行的改性研究.     

用改性酚醛补强树脂提高三角胶硬度

研究了改性酚醛补强树脂（BQ－205A）对子午线轮胎三角胶的补强作用。结果表明,BQ－205A可提高胶料硬度4－5度,胶料的拉伸强度、撕裂强度等性能也有提高。BQ－205A的分散性及与胶料的相容性都较好,挤出型胶表面光滑,成品轮胎性能良好。     

金刚石砂带用酚醛树脂胶粘剂的初步改性研究

酚醛树脂是砂带生产的常用胶粘剂,但由于金刚石与普通磨料在性能上有很大的差别,金刚石与涂附层的粘结技术及其粘结剂本身的耐磨性、柔软性等很难解决,从而成为金刚石砂带发展的一个瓶颈。因此,必须在普通磨料砂带研究的基础上进行改性,才能得到性能优越的金刚石砂带。试验分别将4条不同添加剂和采用不同植砂工艺制成的砂轮进行测试,研究了偶联剂,植砂方式及金刚石等因素对砂轮质量的影响。     

双马改性酚醛树脂的耐热性及热分解动力学研究

采用二笨甲烷型双马来酰亚胺对酚醛树脂进行改性,制备出一种耐热性良好的改性酚醛树脂.采用热重分析法研究了双马来酰亚胺改性酚醛树脂的热分解动力学,并用Kissinger法、Ozawa法、Crane法计算其热分解动力学参数.结果表明,改性树脂的平均表观活化能为376.144kJ/mol,反应级数为0.940,其热分解分为3个...     

酚醛树脂的复合改性研究进展

综述了酚醛树脂增韧和耐热复合改性的研究进展,分析了各种方法的改性机理及研究现状。包括用橡胶、CNSL、桐油、新型固化剂改性酚醛树脂的韧性,用钼、硼、无机纳米材料、聚酸亚胺改性酚醛树脂的耐热性。并对酚醛树脂复合改性方法的发展前景作出了分析。     

酚醛改性苯并(噁)嗪树脂耐烧蚀材料的研究

对不同组成苯并口恶嗪/酚醛共混树脂体系进行了研究,内容包括共混树脂的反应动力学参数计算、共固化机理、热分解动力学以及耐烧蚀性能等。结果表明:酚醛与苯并口恶嗪树脂共混后可以改变苯并口恶嗪的固化机理,酚醛树脂的加入使口恶嗪分子由热开环变为活泼氢开环,在较低温度下就可以反应,降低了固化反应温度。同时共混树脂可以使固化过程收缩率和小分子挥发物比传统的酚醛树脂低,可以减少烧蚀试样的表面裂纹,致密的碳化层具有一定附着强度,提高了共混树脂烧蚀性能。该共混体系可以作为宇航领域中1种性能优良的耐烧蚀树脂体系。     

用于镁碳砖粘合剂的纳米炭黑改性酚醛树脂的研究

利用纳米炭黑对镁碳砖生产用酚醛树脂进行了改性。改性的酚醛树脂常温黏度不超过100Pa·s,热分解温度比普通酚醛树脂提高了约170℃,碳氧化温度提高了约178℃。FESEM照片显示,改性酚醛树脂中炭黑粒子呈近球形,粒径为20～50nm,分散均匀基本无团聚。