超支化烯丙基聚硅氮烷-巯基化合物体系紫外光固化研究

采用等温差示光量热扫描技术(DPC)研究了超支化烯丙基聚硅氮烷-巯基化合物体系的紫外光固化.对比了超支化聚合物-巯基化合物体系、二官能烯丙基硅氮烷-巯基化合物体系和超支化自聚体系的紫外光固化特性,结果表明超支化-巯基化合物体系可在引发剂浓度低(0.1wt%)、辐照强度低(5mW/cm2)的情况下迅速发生光固化反应;与超支化自聚反应相比固化速率高、双键转化率高;而与低官能-巯基化合物体系相比,由于超支化分子结构的独特性,导致固化速率快,双键转化率偏低.对引发剂浓度、辐照强度和反应温度对固化行为的影响表明,在引发剂浓度不超过0.5wt%和辐照强度不大于30.50mW/cm2时,反应速率分别与引发剂浓度和辐照强度的1/2次方成线性关系.运用带扩散因子的自催化固化动力学模型研究了不同温度下的固化行为,计算出特定条件下的光固化动力学参数,表观总反应级数约为8.76,表观活化能为13.97kJ/mol.     

紫外光固化超支化聚硅氧烷的合成及其光固化动力学研究

利用γ-甲基丙烯酰氧基丙基三甲基硅氧烷的受控水解反应即A2-B3单体对法来制备超支化聚硅氧烷,并对合成出的聚合物通过FT-IR、1H-NMR和多角度激光光散射技术(MALLS)进行了表征.结果表明,所得聚合物具有超支化结构且分子中含有大量活性官能团,从而可以实现紫外光引发固化.通过等温差示光量热实验(DPC)研究了聚合物结构、引发剂用量、光强度和聚合温度对聚合物光固化行为的影响规律,并得到了其中一种聚合物的光固化动力学参数,光固化反应总级数约为3,表观活化能为16.9kJ/mol.     

2,2′-二邻甲氧基苯基-4,4′,5,5′-四苯基-1,2′-二咪唑复合光引发体系的光聚合动力学研究

本文研究了对2,2′-二邻甲氧基苯基-4,4′,5,5′-四苯基-1,2′-二咪唑(BMOIM)复合光引发体系引发聚合动力学过程.采用紫外光谱仪对引发剂、供氢体、增感剂在紫外区的吸收谱图进行了表征.利用实时红外光谱仪对复合光引发体系引发聚合动力学过程进行实时监测,考察了不同光强、引发剂浓度以及不同官能度单体对反应速率及最终双键转化率的影响.结果表明,在引发剂浓度为0.6%(质量分数)时,20s内双键转换率达到96%,随着引发剂浓度的提高,聚合速率增大.聚合速率以及最终双键转化率随着光强增大而增大;双官能团单体的最终双键转化率比三官能团单体的最终双键转化率要高.     

吡咯烷基-N-甲酸-丙烯酸乙二醇酯光聚合动力学的研究

采用实时红外技术对所合成的活性稀释剂吡咯烷基-N-甲酸-丙烯酸乙二醇酯的聚合动力学进行了测试.研究了光强、引发剂浓度及引发剂种类对其光聚合的影响.结果表明:光强越强、引发剂浓度越大,聚合速率越高,但是反应的最终双键转化率基本不变,均能达到100%左右.引发剂种类对其光聚合的最终双键转化率的影响不是特别明显,但对聚合速率有一定的影响.     

树枝状醚酰胺多官能团(甲基)丙烯酸酯低聚物的合成及其紫外光固化性能的研究

合成了树枝状(甲基)丙烯酸化醚酰胺低聚物,采用拉曼光谱、光-差热分析和动态力学热分析方法对其紫外光固化动力学和固化膜热机械性能进行了研究.结果表明,这种树枝状低聚物在紫外光照下双键转化率可达80%以上,且其最大反应速率、固化膜的软化温度和玻璃化转变温度随双键浓度的增大而提高.     

可聚合二苯甲酮类光引发剂的合成及其光聚合性能研究

以4-(2,3-环氧丙氧基)二苯甲酮(EBP)和丙烯酸为原料,通过开环反应合成了含有不饱和双键的可聚合光引发剂4-(丙烯酸-2-羟基丙酯-3-氧基)二苯甲酮(AEBP).采用红外光谱(FT-IR)、核磁共振氢谱(¹HNMR)对其结构进行表征,利用紫外吸收光谱对AEBP的紫外吸收波长进行表征,通过实时红外(RT-IR)研究了AEBP引发丙烯酸酯单体的光聚合动力学.采用萃取法对比了BP与AEBP引发固化体系后的迁移性.结果表明,随AEBP浓度增加,单体最终转化率增加;当助引发剂N,N-二甲氨基苯甲酸-乙酯(EDAB)浓度为1.2%时,单体最终双键转化率最高;AEBP对双官能度单体的引发效率较之三官能度单体的好;聚合速率随光照强度的增强而变快;固化后AEBP的迁移性比传统的BP大大降低.     

光/潮气双重固化聚氨酯涂层的制备及性能研究

以甲苯-2,4-二异氰酸酯(TDI)和二乙醇胺(DEOA)为原料一步法合成了超支化聚氨酯,对其改性制备了光固化超支化聚氨酯丙烯酸酯(HPUA)和一系列双重固化(UV/潮气)超支化聚氨酯丙烯酸酯(DHPUA),使用傅立叶红外光谱(FT-IR)、核磁共振氢谱(1H-NMR)和碳谱(13C-NMR)以及凝胶色谱(GPC)对其分子结构进行了表征.并以其为预聚物制备光固化涂层,通过对双重固化涂层的表面形貌、热性能和物理性能的研究,结果表明,超支化双重固化涂层经过潮气固化后,涂层表面的粗糙度随着树脂中硅氧烷端基的含量的增加先下降后上升;超支化双重固化涂层的物理性能和热稳定性都随着树脂中硅氧烷端基的含量的增加而提升.     

可紫外光固化的超支化聚硅氧烷合成及固化研究

同线型聚硅氧烷聚合物相比，超支化聚硅氧烷聚合物具有低粘度、高反应活性和良好的相容性等特点，其中以制备超支化的聚硅氧烷基硅氧烷和聚烷氧基硅氧烷为主．对于超支化聚硅氧烷主要是以ABx（X=2～6）（其中A为双键，B为硅氢键）型单体为原料，在氯铂酸或Pt／C的催化下，通过硅氢加成反应一步制备，最终聚合物的端基（B）为硅氢键，而双键则完全反应，此外也可通过含不同数目烷氧基硅烷的水解缩合制备超支化聚硅氧烷．     

2-(4-甲氧基苯基)-4,6-双(三氯甲基)-S-三嗪光引发剂的合成及其光聚合动力学性能研究

以对甲氧基苯甲腈和三氯乙腈为原料合成了光引发剂2-(4-甲氧基苯基)-4,6-双(三氯甲基)-S-三嗪(MBTT),通过傅里叶红外光谱仪、核磁共振仪和紫外吸收光谱对所合成的产物结构进行了表征.并利用实时红外(RT-IR)对该引发剂进行了光聚合反应动力学研究,考察了单体、引发剂浓度和光强对引发速率及单体转化率的影响.结果表明,MBTT是一种高效的紫外光引发剂,在引发剂用量为0.1%时光聚合的单体转化率就能达到90%;随着光强的增大,单体的双键转化率和最大反应速率都增大,诱导期缩短;双丙烯酸酯类单体的双键转化率比三丙烯酸酯类单体的双键转化率要高.     

巯基/(甲基)丙烯酸(甲基)烯丙酯光固化特性

通过对羧酸盐法改进后合成同时含有高活性的丙烯酸酯型C=C和低自由基活性的烯丙基型C=C的烯类单体(甲基)丙烯酸(甲基)烯丙酯,以实现(甲基)丙烯酸酯类紫外光固化与巯/烯光聚合结合在二元体系中;并以1173为光引发剂,利用实时红外(RT-IR)跟踪此类烯烃与三羟甲基丙烷三(3-巯基丙酸酯)(TMMP)光固化过程,探究烯烃结构、光强和引发剂用量对含有两类碳碳双键的烯类单体与巯基化合物二元体系的光固化行为的影响.研究发现,这类二元巯-烯光聚合反应中均有(甲基)丙烯酸酯双键的反应活性最大,(甲基)烯丙基次之,巯基的反应活性最小;甲基取代在烯烃的不同C=C上,对巯-烯光固化特性影响不同,甲基取代在烯丙基C=C上比甲基取代在丙烯酸基C=C上对巯-烯光固化行为影响更大;巯基最终转化率随甲基取代基数目增多而减少;丙烯酸甲基烯丙酯体系中两类双键(丙烯酸型/甲基烯丙基型)反应活性几乎相同且均具有高的转化率.     

Study on the chemical modification of epoxy/anhydride thermosets using a hydroxyl terminated hyperbranched polymer

Mixtures of diglycidylether of bisphenol A (DGEBA) resin and commercially available hyperbranched polyester (HBP) Boltorn H30 were cured by anhydride to covalently bond the hydroxyl end groups in HBP with the epoxy resin. The curing mixtures were investigated by Differential Scanning Calorimetry (DSC) to study the curing evolution and to evaluate the kinetic parameters. DSC studies suggested that HBP could increase the curing rate of epoxy/anhydride systems at low conversions, but it produced a decelerative effect in the last stages of the curing. The influence of the HBP content and the proportion of anhydride on the curing conversions were discussed in detail. The addition of a tertiary amine was proved to decrease the curing temperatures. By Fourier Transform Infrared Spectroscopy (FTIR) the reaction of hydroxyl groups during the whole process was confirmed. By the determination of the conversion at the gelation, we could prove that it increased on increasing the proportion of HBP in the reactive mixture. By Thermomechanical Analysis (TMA) we could determine a reduction of the shrinkage after gelation.     

Influence of temperature and light intensity on the photocuring process and kinetics parameters of a pigmented UV curable system

The photopolymerization of pigmented coatings is a great challenge and hardly investigated in the literature. Therefore, in this work, the effect of photopolymerization temperature and light intensity on the curing behavior of a TiO₂-pigmented UV curable epoxy acrylate system was investigated by using photo-differential scanning calorimetry (photo-DSC) analysis. The rate of conversion and ultimate conversion at four different temperatures (i.e., 25, 45, 65, and 85 °C) and four light intensities (i.e. 2, 20, 40 and 80 mW cm^?2) for unpigmented and pigmented formulations were measured. The effect of photo-polymerization temperature and light intensity on the kinetics constants was also evaluated. It was observed that the rate of conversion and final conversion values were affected by the temperature and UV-light intensity. It was seen that the rate of conversion and ultimate conversion had their maximum values at 65 °C for unpigmented formulations. However, in pigmented formulations, these two parameters improved by increasing the temperature even up to 85 °C. Increasing the temperature caused an increase in the amount of propagation and termination rate constants in both pigmented and unpigmented formulations although the changes in the pigmented formulation were more pronounced. It was observed that the rate of polymerization and ultimate conversion for unpigmented formulations increased by increasing the light intensity up to 20 mW cm^?2 and then decreased. On the other hand, it was found that these two parameters increased by increasing light intensity up to 40 mW cm^?2 when pigmented formulations used. Finally, the dependence of termination and propagation kinetics constants on light intensity was established for both unpigmented and pigmented coatings.     

Thermal and mechanical properties of a dendritic hydroxyl‐functional hyperbranched polymer and tetrafunctional epoxy resin blends

Blends of a tetrafunctional epoxy resin, tetraglycidyl‐4,4′‐diaminodiphenylmethane (TGDDM), and a hydroxyl‐functionalized hyperbranched polymer (HBP), aliphatic hyperbranched polyester Boltorn H40, were prepared using 3,3′‐diaminodiphenyl sulfone (DDS) as curing agent. The phase behavior and morphology of the DDS‐cured epoxy/HBP blends with HBP content up to 30 phr were investigated by differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), and scanning electron microscopy (SEM). The phase behavior and morphology of the DDS‐cured epoxy/HBP blends were observed to be dependent on the blend composition. Blends with HBP content from 10 to 30 phr, show a particulate morphology where discrete HBP‐rich particles are dispersed in the continuous cured epoxy‐rich matrix. The cured blends with 15 and 20 phr exhibit a bimodal particle size distribution whereas the cured blend with 30 phr HBP demonstrates a monomodal particle size distribution. Mechanical measurements show that at a concentration range of 0–30 phr addition, the HBP is able to almost double the fracture toughness of the unmodified TGDDM epoxy resin. FTIR displays the formation of hydrogen bonding between the epoxy network and the HBP modifier. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 417–424, 2010     

Phase separation,porous structure,and cure kinetics in aliphatic epoxy resin containing hyperbranched polyester

Thermosetting blends of an aliphatic epoxy resin and a hydroxyl‐functionalized hyperbranched polymer (HBP), aliphatic hyperbranched polyester Boltorn H40, were prepared using 4,4′‐diaminodiphenylmethane (DDM) as the curing agent. The phase behavior and morphology of the DDM‐cured epoxy/HBP blends with HBP content up to 40 wt % were investigated by differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), and scanning electron microscopy (SEM). The cured epoxy/HBP blends are immiscible and exhibit two separate glass transitions, as revealed by DMA. The SEM observation showed that there exist two phases in the cured blends, which is an epoxy‐rich phase and an HBP‐rich phase, which is responsible for the two separate glass transitions. The phase morphology was observed to be dependent on the blend composition. For the blends with HBP content up to 10 wt %, discrete HBP domains are dispersed in the continuous cured epoxy matrix, whereas the cured blend with 40 wt % HBP exhibits a combined morphology of connected globules and bicontinuous phase structure. Porous epoxy thermosets with continuous open structures on the order of 100–300 nm were formed after the HBP‐rich phase was extracted with solvent from the cured blend with 40 wt % HBP. The DSC study showed that the curing rate is not obviously affected in the epoxy/HBP blends with HBP content up to 40 wt %. The activation energy values obtained are not remarkably changed in the blends; the addition of HBP to epoxy resin thus does not change the mechanism of cure reaction of epoxy resin with DDM. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 889–899, 2006     

UV-curable epoxy systems containing hyperbranched polymers: Kinetics investigation by photo-DSC and real-time FT-IR experiments

The effect of the presence of a hyperbranched OH-functionalized polymer (HBP) on the kinetics of cationic photopolymerization of an epoxy system was investigated employing two complementary techniques, photo-DSC and real-time FT-IR spectroscopy.Lower rates of cross-linking reactions and higher conversion degrees were obtained in photo-DSC experiments with respect to real-time FT-IR spectroscopy. A limited amount (10% wt) of HBP influenced to a certain extent the cure kinetics of the epoxy resin followed by RT-IR; a final conversion of epoxy groups equal to 100% was achieved by increasing the content up to 20% wt The addition of 10% wt of HBP leaves the cure kinetics of the CE resin studied by p-DSC almost unchanged. By increasing the HBP content, a slightly lower reaction rate is observed at lower reaction times. The presence of the HBP produced a continuous decrease of the T_g of the UV-cured epoxy resin but only modest reductions in its thermo-oxidative stability.     

UV‐curable acrylate‐based nanocomposites: effect of polyaniline additives on the curing performance

Composites of nanostructured polyaniline (PANI) conducting polymer in a polyester acrylate (PEA) formulation were made to provide conductive organic coatings. The effect of the presence and amount of PANI on the photocuring performance of the ultraviolet (UV)‐curable acrylate system has been investigated employing real‐time Fourier transform infrared spectroscopy as the main technique. Longer initial retardation of the radical polymerization and lower rates of cross‐linking reactions were observed for dispersions containing PANI of higher than 3wt.%. The PEA/PANI samples were more affected than the neat PEA resin by the changes in UV light intensity and oxygen accessibility during UV curing. Samples with higher PANI content, of up to 10wt.%, were tested and could be partially cured even at UV light intensities as low as 2 mW cm^?2 when the oxygen replenishment into the system was inhibited. Thermal analysis revealed that the presence of PANI did not induce any significant change in Tg of the cured system, meaning that early decrease in mobility and vitrification is not the reason for lower ultimate conversion of the dispersions with higher PANI content compared with the neat PEA resin. Curing under strong UV lamps, of 1.5 W cm^?2 intensity, made it possible to reach high degrees of conversion on films with similar mechanical properties independent of the PANI content. Copyright © 2013 John Wiley & Sons, Ltd.     

Curing kinetics of epoxy resins with hyperbranched polyesters as toughening agents

The effects of hyperbranched polyesters on the cure kinetics of diglycidyl ether of bisphenol A (DGEBA) in the presence of m‐phenylene diamine were investigated with nonisothermal differential scanning calorimetry. The results showed that the addition of hyperbranched polyesters enhanced the cure reaction of DGEBA with m‐phenylene diamine, and this resulted in a reduction of the peak temperature of the curing curve and the activation energy because of the low viscosity and large number of terminal hydroxyl groups. However, when linear poly(ethylene glycol) was added, the activation energy of the blends also slightly decreased, whereas the peak temperature of the curing curve increased. The curing kinetics of the blends were calculated by the isoconversional method of Málek. The two‐parameter autocatalytic model (i.e., the ?esták–Berggren equation) was found to be the most adequate for describing the cure kinetics of the studied systems. The obtained nonisothermal differential scanning calorimetry curves showed results in agreement with those theoretically calculated. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 2649–2656, 2004     

具有可控温敏相变行为的四氢呋喃-缩水甘油超支化共聚醚的合成

采用四氢呋喃(THF)和缩水甘油(glycidol)进行阳离子开环共聚,一步合成了主链中含有柔性聚四氢呋喃线型链段的温敏性超支化共聚醚.采用定量13C-NMR确定了共聚醚的超支化结构,同时计算了其支化度.利用体积排除色谱-多角度激光光散射(SEC-MALLS)对聚合物分子量及分布进行了表征.紫外-可见光光谱(UV)测试发现共聚醚水溶液透过率在最低临界溶解温度(LCST)附近呈现剧烈变化,但是其相变速率缓慢,相变平衡时间可达30 min;且聚合物溶液的相变速率和紫外光透过率变化具有温度依赖性.采用透射电镜(TEM)对相变过程观察后发现,这种缓慢相变过程是由于超支化共聚醚组装形成的胶束随温度升高发生不同程度聚集所致.