Synthesis and characterization of novel chain‐extended bismaleimides containing fluorenyl cardo structure

Novel fluorenyl cardo chain‐extended bismaleimides (FCCEBMIs) were synthesized by reacting maleic anhydride with fluorenyl cardo diamine and different dianhydrides. FCCEBMIs were characterized by FT‐IR spectra (FT‐IR), ¹H NMR, and elemental analysis. All FCCEBMI monomers were readily soluble in a variety of organic solvents, such as N‐methyl‐2‐pyrrolidinone, N,N‐dimethyl acetamide, chloroform (CHCl₃), methylene chloride (CH₂Cl₂), dimethyl sulfoxide, and tetrahydrofuran when compared with 9,9‐bis(4‐maleimidophenyl) fluorene. Curing process was investigated by differential scanning calorimetry. Thermal properties of the cured FCCEBMIs were characterized by thermogravimetry analysis, the cured products are stable up to 430°C. The results show that the FCCEBMIs with imide structure improve significantly the solubility of bismaleimide (BMI) in organic solvents without sacrificing thermal properties of cured BMIs. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

喷雾技术制备含有机硅消泡剂的洗衣粉

介绍了一种高性价比的适用于喷雾技术的液态有机硅消泡剂，并对其喷雾混合添加工艺进行了阐述。通过对使用喷雾技术制备的含有该消泡剂的洗衣粉的泡沫控制性能和稳定性能测试，证明该有机硅消泡剂能有效控制洗衣粉的泡沫，增加低泡洗衣粉的稳定性。     

低水溶解度聚磷酸铵的制备与表征

用红外光谱分析、X-射线衍射分析表征了不同聚磷酸铵(APP)的结构,对APP进行了热分析和粒度分析。用特殊方法制备的低水溶解度的APP在水中的溶解度(20℃)由原来的 8. 6×10-3 g/g降为 1. 17×10-3g/g,接近于Exolit422APP的溶解度 1. 2×10-3 g/g。     

苯基硅橡胶的溶解性与溶液聚合研究

研究了苯基硅橡胶的溶解性和溶液聚合制备方法。研究结果表明,苯基硅橡胶在下列溶剂中的溶解性大小依次为苯、甲苯、石油醚、氯苯;经过溶胀的苯基硅橡胶,其溶解效果较好。溶液聚合制备的苯基硅橡胶摩尔质量大于本体聚合产物,摩尔质量分布相对较宽;采用旋转蒸发脱低沸效果良好。     

有机硅改性环氧树脂粘合剂的研制

采用含活性氨基的SR22000有机硅树脂、ECC202环氧树脂、K-12固化剂和2E4MI固化促进剂为原料,通过配方设计,制得了有机硅改性环氧树脂粘合剂体系,并研究了SR22000的用量对粘合剂体系性能的影响。     

Synthesis and properties of self-healing cross-linked nonisocyanate polyurethanes from biobased diglycerol bis(cyclic carbonate)

A simple and green method was established to prepare self-healing cross-linked nonisocyanate polyurethanes (SH-cNIPUs) from biobased diglycerol bis(cyclic carbonate) (DGDC). Two nonisocyanate polyurethane prepolymers with furan terminal groups (tFU-NIPUs) were synthesized through a ring-opening reaction of DGDC with furan methylamine and trimethylolpropane tris(poly[propylene glycol], amine terminated) ether, or tris(2-aminoethyl) amine under mild conditions. The SH-cNIPUs were prepared via a Diels–Alder reaction between tFU-NIPUs and a bismaleimide. SH-cNIPUs were characterized by ATI-FTIR, ¹H NMR, differential scanning calorimetry, polarized optical microscope, and tensile strength after being damaged and healed. SH-cNIPUs with glass transition temperature from 8 to 49°C, tensile strength up to 21 MPa, and self-healing efficiency from 67 to 80% were successfully synthesized.     

Synthesis and characterization of pyridine and anthracene containing bismaleimides,bisnadimides and polyaspartimides

Three different novel diamines containing pyridine and anthracene moiety were prepared and subsequently converted into bismaleimides (BMI) and bisnadimides (BNI) and their structure was confirmed by elemental analysis, FT-IR, ¹H-NMR and ¹³C-NMR techniques. Chain extension of bismaleimides and bisnadimides was accomplished by incorporating various ether or ester groups. Owing to pendant anthracene moiety, pyridine unit and flexible linkages, the bismaleimides and bisnadimides were found to possess an excellent balance of properties; solubility and thermal stability and the curing behaviour was investigated by differential scanning calorimeter. In addition, a series of polyaspartimides containing anthracene and pyridine unit was prepared by the polyaddition of bismaleimides with various diamines via a Michael-type addition. The thermal stability of bismaleimides, bisnadimides and polyaspartimides was evaluated by thermo gravimetric analysis. All the polyaspartimides are soluble in many organic solvents and exhibit T _g in the range of 189–242 °C and 10% weight loss (T ₁₀) takes place in the range of 389–487 °C in N₂.     

耐高温强碱有机硅消泡剂的研制

实验从消泡活性物的研制入手,通过单因素实验和L16(45)正交试验确定了影响消泡剂抑泡性能的条件,优选合成工艺条件为:m(甲基硅油):m(羟基硅油)=4:1,w(MQ硅树脂)=10%,M/Q(MQ硅树脂单官能链节Me3SiO0.5和四官能链节SiO4/2的摩尔比)为0.8,w(疏水白炭黑)=8%,w(氢氧化钾)=2%,交联反应温度和时间分别为150℃和4 h.用自制的两种硅聚醚为主乳化剂对上述消泡活性物进行了乳化,制得耐高温强碱有机硅乳液消泡剂.     

Maxam推出用于苛刻工况的新优质实心防滑轮胎

采用了四甲基四乙烯基环四硅氧烷和四甲基四氢环四硅氧烷在铂金催化剂的作用下发生硅氢加成反应得到了高交联密度的硬质硅橡胶,制备过程中采用了“液面悬浮”和“阶梯升温”的工艺。利用差示扫描量热仪、傅里叶红外光谱仪、原子力显微镜、邵氏硬度计和热重分析仪分别对其固化过程、表面性能、硬度和热稳定性进行研究,并利用了平衡溶胀法计算了其交联密度。实验结果表明：阶梯升温能有效控制交联反应;硅橡胶具有极低的粗糙度,均方根粗糙度Rq为1.74 nm,平均粗糙度Ra为1.39 nm;邵氏D硬度为78.3;交联密度为2.87′10-3 mol/cm-3;硅橡胶在质量损失为5%时,对应温度为602.1 o C,最终的残余量为83.57%。     

Radiation synthesis of polysilane-modified graphene oxide for improving thermal conductivity and mechanical properties of silicone rubber

Functionalized graphene oxide (named GO-Si) was synthesized with graphene oxide and triethoxyvinylsilane (TEVS) using tetrahydrofuran solution by γ-ray irradiation. TEVS was successfully covered onto GO sheets, and the polysilane content on GO-Si was increased upon increasing the absorbed dose. The structures of GO-Si were verified by atomic force microscopy, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy. The resultant GO-Si was dispersed into α,ω-dihydroxypolydimethylsiloxane to prepare room temperature vulcanized silicone rubber composites (named SR/GO-Si) by solution casting. The dispersion of GO-Si was more uniform than that of GO. Compared to that of pure SR, the thermal conductivity of SR/GO-Si-1.95 composites was increased 1.5-fold, and its tensile strength and elongation at break increased 78.6 and 71.4%, respectively. It was expected that SR/GO-Si would have potential application as the thermal interface material. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47776.     

Preparation and thermal degradation behavior of room temperature vulcanized silicone rubber-g-polyhedral oligomeric silsesquioxanes

Room temperature vulcanized (RTV) silicone rubber-g-polyhedral oligomeric silsesquioxanes (POSS) was prepared and its thermal degradation behavior and thermo-oxidative stability were investigated by thermogravimetric analysis (TGA). The results demonstrated that the chemical incorporation of POSS into polydimethylsiloxane (PDMS) chains significantly enhanced thermal stability of RTV silicon rubber in both nitrogen and air atmosphere. The degradation behavior was further monitored by TGA coupled with real time Fourier transform infrared spectra (FTIR), and the residues were characterized by FTIR and X-ray photoelectron spectroscopy (XPS). It was found that the remarkable improvement in thermal stability could be attributed to the following reasons: (1) the branched structure of RTV silicone rubber-g-POSS and interaction between POSS molecules and PDMS chains; (2) POSS traps generated and grafted or cross-linked structure formed; (3) intumescent ceramic protective barrier formed; (4) the perfect distribution of POSS in RTV silicone rubber-g-POSS.     

纳米SiO2/OTAC协同稳定Pickering乳液聚合制备水基硅橡胶

以十八烷基三甲基氯化铵(OTAC)协同纳米SiO₂制备Pickering乳液,碱性条件下引发D₄开环聚合制备线性聚硅氧烷(PDMS),然后加入交联剂KH560制备阳离子型水基硅橡胶乳液。考察了纳米SiO₂与OTAC用量对Pickering乳液性能的影响,通过zeta电位、TEM及SEM研究了OTAC在SiO₂表面的吸附状态,用FT-IR、²⁹Si NMR对水基硅橡胶的结构进行了表征,研究了KH560用量对橡胶膜对水接触角和邵氏硬度的影响。结果表明: w(SiO₂)=2.0%时,乳液流动性和稳定性最优;w(OTAC) = 1.75%时,OTAC在纳米SiO₂表面的单层吸附达到饱和,单体转化率为89%,粒径为617 nm,zeta电位接近零点,PDMS的数均分子量为16036,PDI为1.485;w(KH560)=5.0%时,KH560与PDMS充分水解缩合,硅橡胶膜憎水性和硬度显著提高。     

硅橡胶隔热复合材料的制备及性能

采用空心玻璃微珠（HGB）和膨胀蛭石（EVMT）作为隔热填料,分别与高温硫化硅橡胶（HTV）共混制备HGB/HTV和EVMT/HTV隔热复合材料,并考察了隔热填料的种类和用量对隔热复合材料的隔热性能和力学性能的影响。结果表明,随着HGB和EVMT用量的增加,隔热复合材料的导热性能明显下降。相比于HTV试样,当HGB与HTV的质量比为20/100,EVMT与HTV的质量比为10/100时,隔热复合材料的导热系数分别下降了20.44%和12.34%。HGB和EVMT均能提高HTV隔热复合材料的100%定伸应力和邵尔A硬度,降低其拉伸强度与扯断伸长率。当HGB与HTV的质量比为20/100,EVMT与HTV的质量比为10/100时,隔热复合材料的拉伸强度分别为10.51 MPa和11.59 MPa,邵尔A硬度分别为71.6和59.1。     

Synthesis and characterization of novel wholly para‐oriented aromatic polyamide‐hydrazides containing sulfone‐ether linkages

Four novel wholly para‐oriented aromatic polyamide‐hydrazides containing flexibilizing sulfone‐ether linkages in their main chains have been synthesized from 4‐amino‐3‐hydroxy benzhydrazide (4A3HBH) with either 4,4′‐sulfonyldibenzoyl chloride (SDBC), 4,4′‐[sulfonylbis(1,4‐phenylene)dioxy]dibenzoyl chloride (SODBC), 4,4′‐[sulfonylbis(2,6‐dimethyl‐1,4‐phenylene)dioxy]dibenzoyl chloride (4MeSODBC), or 4,4′‐(1,4‐phenylenedioxy)dibenzoyl chloride (ODBC) via a low‐temperature solution polycondensation reaction. A polyamide‐hydrazide without the flexibilizing linkages is also investigated for comparison. It was synthesized from 4A3HBH and terephthaloyl chloride (TCl) by the same synthetic route. The intrinsic viscosities of the polymer ranged from 2.85 to 4.83 dL g^?1 in N,N‐dimethyl acetamide (DMAc) at 30°C and decreased with introducing the flexibilizing linkages into the polymer. All the polymers were soluble in DMAc, N,N‐dimethyl formamide (DMF), and N‐methyl‐2‐pyrrolidone (NMP), and their solutions could be cast into films with good mechanical strengths. Further, they exhibited a great affinity to water sorption. Their solubility and hydrophilicity increased remarkably by introducing the flexibilizing linkages. The polymers could be thermally cyclodehydrated into the corresponding poly(1,3,4‐oxadiazolyl‐benzoxazoles) approximately in the region of 295–470°C either in nitrogen or in air atmospheres. The flexibilizing linkages improve the solubility of the resulting poly(1,3,4‐oxadiazolyl‐benzoxazoles) when compared with poly(1,3,4‐oxadiazolyl‐benzoxazoles) free from these linkages. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Preparation,structure characterization,and thermal performance of phenyl‐modified MQ silicone resins

Methyl‐ and phenyl‐modified MQ resins have been prepared by cohydrolysis and condensation‐polymerization of the prepolymer of sodium silicate with SiO₂/Na₂O = 3.33 using the ethanol solution of hexamethyldisiloxane (MM), 1,1,3,3‐tetramethyl‐1,3‐divinyldisiloxane (TMDVS), methyldiphenylethoxysilane (MDPES), dimethylphenylethoxysilane (DMPES), or their dimers. The influence of different end‐capping agents on the composition and properties of the MQ resins has been investigated. Thermogravimetric analysis and differential scanning calorimetry results indicate that when the MQ resins are end capped with DMPES instead of MDPES, the resins were more easily purified and almost no high boiling point residuals were found in the phenyl MQ resins. The refractive indexes of the MQ resins were significantly affected by the phenyl group and their values could be adjusted by changing the amount of DMPES. The structures of the resins were characterized by ¹H‐NMR and FT–IR spectroscopy. The M/Q ratios in the prepared MQ resins were calculated from the ¹H‐NMR spectra or from elemental analysis or both. The M/Q values obtained agreed well with the changes of appearance and thermal stabilities of the MQ resins. The thermal stabilities of the MQ resins were greatly enhanced when DMPES was used. Phenyl‐modified MQ resins were in the form of white powders due to the rigidity of the phenyl group while methyl MQ resins exhibited a range of appearances, from transparent liquids to white powders, with the reduction of M/Q values. The method developed to calculate the M/Q values is useful for the characterization of MQ resins and their derivatives. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

甲基苯基硅树脂的制备工艺优化及阻燃性能

以苯基甲氧基硅烷和甲基甲氧基硅烷为原料,用水解缩合法制备硅树脂阻燃剂,通过对反应时间、反应温度、催化剂量和封端时间等因素的正交实验分析,优化硅树脂阻燃剂制备条件.结果表明：硅树脂具有良好的热稳定性,在800℃、N₂气氛下,热失重低于39%,其热稳定性越好,对聚碳酸酯（PC）的阻燃效果越佳.在PC中添加5 %（质量）优化条件制得的硅树脂就能使其氧指数（OI）从26.0提高到34.0.     

A kinetic model of the cycloaddition reactions between cyclopentadiene and 1,3-butadiene for synthesis of 5-vinyl-2-norbornene

Under high temperature and pressure, a continuous tubular reactor was successfully utilized to investigate the kinetics of 5-vinyl-2-norbornene (VNB) production. The process involved multiple cycloaddition reactions between cyclopentadiene (CPD) and 1,3-butadiene (BD). The results, spanning a wide range of operating conditions, indicate that higher temperature (180°C) and proper residence time (72 min) were conducive to efficient synthesis of VNB. The apparent kinetic parameters, including activation energies and pre-exponential factors, were acquired by fitting experimental data under integral operating conditions. The kinetic model was proven effective from a practical point of view in predicting the concentration changes of each product in the range 140 to 180°C and 30 to 80 wt.% concentration. This work provides a solid basis for the optimization of the VNB synthesis process.     

高硬度硅橡胶耐热性能与压缩回弹性能的改善

研究了Al2O3和气相法白炭黑对硅橡胶的增强作用,考察了表面处理Al2O3对不同硬度硅橡胶性能的影响。结果表明,Al2O3增强的硅橡胶老化前后的性能均优于白炭黑填充体系。Al2O3经硅烷偶联剂处理后提高了表面活性。不同硬度混炼胶的并用,可使硅橡胶硬度、耐热性和压缩回弹性满足使用要求。     

硅橡胶耐高温用含铈聚硅氧烷的制备及应用

本文以硅氧烷、氢氧化钾、无水氯化铈为原料,制备了一种与硅橡胶结构相似的含铈硅氧烷(PSC)。研究PSC用量、硅氧烷种类以及不同耐热添加剂对硅橡胶耐高温性能的影响。通过红外光谱对PSC结构进行表征,力学测试、热重分析、扫描电镜研究其加入硅橡胶前后的性能。结果表明：在250℃×24h和300℃×8h热老化条件下,随PSC用量增加,硅橡胶的拉伸强度、断裂伸长率和撕裂强度先增加后降低,硬度基本保持不变,PSC加入量为5%时,材料具有最佳的力学强度。PSC在硅橡胶中分散均匀,其加入起后始分解温度提高了250℃。     

液体乙烯基硅树脂的制备及固化反应动力学

合成了一种液体乙烯基硅树脂,并用FT-IR、GPC、¹H NMR和²⁹Si NMR等手段对其结构进行表征。采用非等温差示扫描量热法（DSC）研究了乙烯基硅树脂/苯基含氢硅油体系的固化反应动力学,用Kissinger方程和高级等转化率法（Vyazovkin方法）分别计算了该体系的表观活化能E_a,用Málek法进行模型拟合动力学分析,通过T-β外推法确定该体系的固化工艺参数。结果表明：Kissinger法和Vyazovkin法得到的活化能分别为85.3 kJ·mol^-1和84.0 kJ·mol^-1,二者所得结果的差别较小;乙烯基硅树脂体系固化动力学符合Šesták-Berggren（m,n）模型,m和n分别为0.092、1.440,拟合曲线与实验的DSC曲线吻合;该树脂体系的近似凝胶化温度为89.1℃,固化温度为127.8℃,后处理温度157.6℃。