光敏聚氨酯丙烯酸酯固化收缩应力的影响因素

光敏聚氨酯丙烯酸酯体系的光固化速度快,然而快速的聚合动力学会导致树脂在光聚合过程中内应力释放受到阻碍,出现严重的聚合收缩现象,使体系双键转化率降低,光固化材料性能较差。为了了解性能与聚合过程之间的关系,文中采用中红外光谱仪和光流变仪相结合的技术来监测光敏聚氨酯丙烯酸酯(PUA)的光聚合过程。结果发现,引发剂含量增加可以提高固化速率,降低聚合过程中的法向应力;UV光强降低会减少收缩应力,但同时也会降低体系的双键转化率。当单体官能度增加,凝胶点推迟出现,收缩应力降低。随着稀释剂单体中乙氧基柔性链增加,固化材料的柔韧性增大,从而收缩应力降低。     

电化学合成聚硅烷的反应速率

采用电化学法,合成出含双键聚硅烷与不含双键聚硅烷,通过FT-IR,UV,1H NMR表征其结构.分别研究了电化学反应体系和直接化学反应体系中Si-Cl键含量的变化,以及加入引发剂蒽对反应速率的影响.结果表明:含双键聚硅烷的合成反应速率快于不含双键的聚硅烷,相同反应电量下含双键聚硅烷反应体系中的Si-Cl键含量比不含双键聚硅烷少10%～15%;在电化学合成聚硅烷的过程中,单体与镁发生的格氏反应在整个反应中占有相当的比例;引发剂蒽的加入能够有效地提高不含双键聚硅烷的反应速率.本文还对电化学合成聚硅烷的反应机理进行了推测.     

薄膜反应器中UV光引发丙烯酰胺反相乳液连续聚合过程

报道了薄膜反应器在UV光直接引发丙烯酰胺(AM)反相乳液聚合中的应用。以OP-10/Span-80为复合乳化剂,环己烷为溶剂,在室温且不使用引发剂,采用UV光直接引发AM反相乳液聚合,所得聚合物相对分子质量达107。考察了单体浓度、光照强度、液体流量、转速等因素对聚合反应的影响。结果表明,单体浓度增加,聚合物相对分子质量提高,聚合速率先增加后减小;随着光强的增大,单体转化率和聚合速率增加,而聚合物相对分子质量下降;随着转速的增加,单体转化率和相对分子质量先增加后降低,当转速为300 r/min时达到最大值。通过调节转盘转速和原料流量得到最优停留时间。     

UV油墨光引发剂在食品包装材料中的残留分析

目的研究UV油墨光引发剂在食品包装材料中的残留行为。方法以2种常用的UV油墨光引发剂EDB和907为研究对象,分别以PET薄膜和铜版纸为承印材料,通过IGT印刷适性仪控制印刷膜层厚度,IGT UV干燥器控制紫外光固化时间,研究光照能量、墨层厚度和油墨浓度对光引发剂在食品包装材料中残留的影响。结果光引发剂残留量会随着光照能量的增加而减少,随着墨层厚度增加而增加。对于PET薄膜,油墨含量高时光引发剂的残留量比油墨含量低时大,而铜版纸结果相反,油墨含量高时光引发剂的残留量较小。结论在实际UV油墨印刷中,应提高光照能量,对于不同的承印材料应采用含量不同的油墨,以减少光引发剂的残留,降低其迁移风险,增加食品包装的安全性。     

樟脑醌(CQ)/脂肪胺引发牙科复合树脂的光聚合动力学研究

采用实时红外技术研究了樟脑醌（CQ）／脂肪胺可见光引发牙科复合树脂聚合的动力学过程。考察了不同胺链长、胺浓度以及光强对牙科修复复合树脂光聚合动力学的影响。结果表明：随着链长的增加，反应速率和转化率都有一定程度的降低，增加引发体系的浓度和增加光强都可以增加反应速率和转化率。     

聚合条件对丙烯酸丁酯反应动力学的影响

采用溶液聚合方法,通过改变聚合条件研究丙烯酸丁酯转化率随聚合时间变化的关系,考察其聚合反应动力学.改变引发剂过氧化苯甲酰(BPO)含量发现,BPO质量百分数提高聚合反应速率加快,单体转化率差别不大;提高温度有利于聚合速率的提高,但同时会导致单体最终转化率的降低;单体浓度越高,聚合速率越快,凝胶化现象明显;采用乙苯为溶剂...     

UV油墨光引发剂与颜料匹配的研究

UV油墨固化体系的关键组分是光引发剂,确定颜料的透光窗口是选择光引发剂的主要依据.阐述了影响油墨固化的相关因素,提出了确定UV油墨透光窗口的方法,并以此为基础讨论了UV油墨光引发剂与颜料匹配和印刷工艺色序的问题.     

环氧单体聚合动力学及体积收缩研究

采用配有水平样品台的实时红外光谱仪(RT-FT-IR)监测三芳基硫金翁盐(UVI-6976和UVI-6992)紫外光引发双酚A型环氧单体(JY-257)光聚合动力学过程,结果表明:配有水平样品台的红外检测动力学得到的数据重现性好;当引发剂UVI-6992的质量分数从0.8%增加到2.3%时,JY-257转化率和聚合速率迅速增加,继续增加引发剂质量分数到5.1%,转化率增加幅度明显减小,且最大聚合速率开始降低;对比两种三芳基硫金翁盐的光引发活性发现,引发剂浓度较低时,UVI-6976的引发活性远远高于UVI-6992;但是当引发剂浓度较高时,二者的引发活性相近;两种引发体系得到的聚合物体积收缩均较低。     

吸收剂含量对电磁吸收喷墨油墨印刷适性的影响

目的制备性能优异的电磁吸收喷墨油墨,研究电磁吸收剂含量对油墨印刷适性的影响。方法测试吸收剂含量不同时的电磁吸收油墨的粒径、表面张力、粘度、光固化速度,研究电磁吸收剂含量的变化对电磁吸收喷墨油墨印刷适性的影响规律,获得最合适的电磁吸收剂用量。结果当吸收剂质量分数为0.025%,0.05%或0.1%时,油墨粒径在200~300 nm范围内呈现正态分布;当吸收剂质量分数为0.2%时,大部分油墨的粒径超过500 nm,分散性相对较差。随着电磁吸收剂质量分数的增加,油墨表面张力和粘度均呈下降趋势。当吸收剂质量分数为0.025%和0.05%时,油墨表面张力分别为25.76,25.94 m N/m,油墨粘度分别为0.1354,0.1083 Pa·s,均与喷墨3D打印机专用树脂表面张力和粘度接近。此外,该2种油墨光固化过程中的相对反应速率与3D打印机专用树脂也较接近。结论经综合考虑,当吸收剂质量分数为0.05%时的油墨印刷适性和固化速度最佳。     

光引发剂对UV柔印油墨固化速度的影响

设计了UV柔印油墨的配方,选用了3种光引发剂制备油墨样品,测试了油墨样品的固化速度.研究结果表明,不同的光引发剂及其用量对油墨固化速度有较大彰响,3种光引发剂中,使用907制备的油墨固化速度最快.采用配方实验的方法研究了复合光引发剂对油墨固化速度的影响,测试结果显示其固化速度低于使用单一光引发剂907的固化速度.油墨样品中引发剂907的含量为8%(质量分数)时固化速度最快.     

UV curing behavior of a highly branched polycarbosilane

The UV curing behavior of a highly branched polycarbosilane (HBPCS) was studied by differential scanning photo calorimeter (DPC) measurements. 2-Hydroxy-2-Methyl-Phenyl-Propane-1-one (Photocure-1173) was selected as photoinitiator. In order to accelerate the curing reaction rate of polycarbosilane, acrylic reactive diluent tripropane glycol diacrylate (TPGDA) was also added to the polymer system. The effect of TPGDA content, photoinitiator concentration, temperature, light intensity, and the curing atmosphere was investigated. The results indicated that the TPGDA greatly enhanced the reaction rate of the HBPCS system. The TPGDA content, photoinitiator concentration, temperature, and light intensity had their own optimal values to get the maximum ultimate conversion percentage and the reaction rate. The oxygen atmosphere helped to increase the final conversion percentage though it could retard the reaction rate.     

Synthesis and photopolymerization kinetics of a photoinitiator containing in-chain benzophenone and amine structure

A photoinitiator HTD bearing in-chain benzophenone (BP) and coinitiator tertiary amine, based on 4-hydroxybenzophenone (HBP), toluene-2,4-diisocyanate (TDI) and N,N-dimethylethanolamine (DMEA), was synthesized and characterized by ¹H-NMR and UV-vis absorption spectroscopy. HTD had longer absorption wavelength in the UV-vis absorption spectra than the low molecular counterpart BP. The kinetics of photopolymerization was studied by real-time Fourier transformation infrared (FTIR) spectroscopy. It showed that HTD was a more effective photoinitiator than BP. When this photointiator was used to initiate polymerization of acrylates, both rate of polymerization and final conversion increased with increase of initiator concentration and light intensity. UV-vis extract analysis showed that the extractability of HTD was much lower than BP/DMEA on the same environment condition.     

Synthesis and photopolymerization kinetics of a photoinitiator containing in-chain benzophenone and amine structure

A photoinitiator HTD bearing in-chain benzophenone (BP) and coinitiator tertiary amine, based on 4-hydroxybenzophenone (HBP), toluene-2,4-diisocyanate (TDI) and N,N-dimethylethanolamine (DMEA), was synthesized and characterized by ¹H-NMR and UV-vis absorption spectroscopy. HTD had longer absorption wavelength in the UV-vis absorption spectra than the low molecular counterpart BP. The kinetics of photopolymerization was studied by real-time Fourier transformation infrared (FTIR) spectroscopy. It showed that HTD was a more effective photoinitiator than BP. When this photointiator was used to initiate polymerization of acrylates, both rate of polymerization and final conversion increased with increase of initiator concentration and light intensity. UV-vis extract analysis showed that the extractability of HTD was much lower than BP/DMEA on the same environment condition.     

Photopolymerization monitoring of ceramic stereolithography resins by FTIR methods

Curing kinetics of UV photocurable acrylate monomer-based ceramic resins were studied using a Fourier Transform Infrared (FTIR) spectroscopy instrument with an internally-mounted UV-curing source, providing real-time quantification of the acrylate double bond conversion with respect to increasing UV dose. The results show that this Real Time FTIR experiment (RTFTIR) provides a simple but valuable means of investigating average photopolymerization kinetics and final conversion in a thin layer of highly loaded ceramic suspension. This RTFTIR technique showed complete agreement with differential photo-calorimetry (photoDSC) experiments performed on the same thickness and amount highly loaded ceramic suspension.FTIR was also used to investigate the curing behavior inside sublayers of the same ceramic suspension. Curing kinetics and final conversion were monitored in these layers, with higher conversion and faster kinetics being observed near the exposed surface. Due to the scattering and absorption effects within the uppermost layers, photopolymerization rate and percent conversion declined as a function of depth from the surface.     

Preparation and properties of cyclic acetal based biodegradable gel by thiol-ene photopolymerization

Synthetic, hydrolytically degradable biomaterials have been widely developed for biomedical use; however, most of them will form acidic products upon degradation of polymer backbone. In order to address this concern, we proposed to fabricate a biodegradable gel based on the crosslinking of a cyclic acetal monomer with reactable diallyl group and multifunctional thiols by thiol-ene photopolymerization. This gel produces diols and carbonyl end groups upon hydrolytic degradation and could be entirely devoid of acidic by-products. Real time infrared spectroscopy was employed to investigate the effect of different light intensities and concentrations of photoinitiator on the polymerization kinetics. With the increase of the concentration of photoinitiator and light intensity, both the rate of polymerization and final double bond conversion increased. Degradation of cyclic acetal based networks was investigated in PBS medium so as to simulate physiological conditions. The remaining mass of the materials after 25 days incubation was 84%. TGA analysis showed that the gels exhibited a typical weight loss (97.2%) at around 378 °C. In vitro cytotoxicity showed that the cyclic acetal based gels had non-toxicity to cell L-929 and had good biocompatibility.     

Coatings obtained through cationic UV curing of epoxide systems in the presence of epoxy functionalized polybutadiene

The cationic photopolymerization of a biscycloaliphatic and a di-glycidyl epoxide monomer was investigated in the presence of an epoxy hydroxy functionalized polybutadiene (PBE). Triphenylsulfonium hexafluoroantimonate was used as photoinitiator. The kinetics of UV curing, in the presence of the additive, was determined via FT-IR analysis, showing an increase of the rate of photopolymerization and of the final epoxy groups conversion. Comparison experiments were performed with hydroxy functionalized polybutadiene. Evidences are obtained that PBE is incorporated via a copolymerization reaction involving the epoxy groups and via a chain transfer reaction involving the OH groups. The investigation of the properties reveals a flexibilization effect due to the presence of the additive, evidenced by a sharp decrease of T _g of the cured films.     

溶剂负载摩擦法评价UV胶印油墨印品固化程度

目的 UV油墨固化程度是印品质量的关键影响因素,开发新型UV油墨固化程度评价方法,用以准确、直观地判断墨层固化程度,指导印刷工艺条件优化。方法 通过调控墨层的UV固化光能量,制备系列不同固化程度的胶印印品,以间歇红外法测定墨层的双键转化率定量分析固化交联反应的程度,进一步以墨层在不同溶剂下的摩擦次数建立墨层固化等级的评价方法。结果 不同UV固化能量下的样品,具有不同的双键转换率,依据不同比例的乙醇与水混合溶剂下的印品耐磨次数可以判定出印品的固化程度。结论 采用溶剂负载摩擦法主观经验判定依赖性低,可实现对UV油墨印品的整体油墨固化程度进行判定,具有良好的生产应用价值。     

Synthesis and photopolymerization kinetics of linear alicyclic urethane acrylate macromonomer in presence of reactive diluents

This study deals with the photopolymerization of a macromonomer in the presence of reactive diluents using Photo Differential Scanning Calorimetry or Photo DSC. The kinetic profiles of these systems showed that the rate of photopolymerization rapidly increases at very early stages of the reaction. The rate of reaction was further found to increase with the addition of crosslinking agents. The addition of trifunctional crosslinking agent to the macromonomeric formulation resulted in a higher polymerization rate and conversion than that of a difunctional crosslinking agent. From the heat flow profiles, the kinetic parameters such as induction time, time to attain peak maximum, rate of maximum polymerization, and final conversion were noted for all the formulations. The initiation of photopolymerization was found to depend on the functionality while the in situ viscosity controlled the time scale for reaction diffusion which resulted in varying levels of conversions. Other parameters such as effect of temperature and concentration of photoinitiator on photocuring kinetics are also discussed.     

Characterization of a nanoparticle-filled resin for application in scan-LED-technology

Scan-LED-technology is a new rapid prototyping technique with increasing applications in the production of custom-made medical products. The present work is dealing with the examination of a silica/urethandimethacrylate (UDMA) nanocomposite for application in scan-LED-technology. The use of specific LED in a photo-DSC unit enables the simulation of crucial parameters of nanoparticle-filled resins for their application in scan-LED-technology. The conversion of double bonds during the curing reaction and the rate of conversion were studied as a function of radiation intensity, silica nanoparticle content, and silanization of the nanoparticles with 3-methacryloyloxypropyl-trimethoxysilane (MPTMS). The conversion of double bonds is increasing with increasing radiation intensity. The increasing conversion of the nanoparticle-filled resins is discussed as a combined effect of increasing nanoparticle content, alternated initiator/double bond ratio and increasing radiation intensity. A significant dependence of the reaction rate on nanoparticle content could not be found. Only for the unfilled resin, the rate was increasing at higher radiation intensities. The influence of residual solvent on conversion and rate of reaction was also analyzed. TGA measurements combined with FTIR were used to study the silanization of the nanoparticles. The silane layer thickness on the surface of the silica nanoparticles was determined.     

Photoactive multi-walled carbon nanotubes: synthesis and utilization of benzoin functional MWCNTs

This study describes a facile method for the synthesis of functionalized multi-walled carbon nanotubes (MWCNTs) carrying photoactive group. The synthesis of MWCNTs-based macro-photoinitiator was achieved by the esterification reaction between benzoin moiety and acyl chloride functional MWCNTs. Synthesized MWCNT-based photoinitiator (MWCNTs–benzoin) was used in the photopolymerization of styrene to yield polystyrene (PS)-grafted MWCNTs (MWCNTs–PS) by “grafting from” method. The efficiency of MWCNTs–benzoin photoinitiator was determined by evaluating the effect of initiator to monomer ratio and reaction period on photopolymerization of styrene. Fourier transform infrared spectroscopy, Raman and X-ray photoelectron spectroscopy analyses confirmed the covalent bonding for functionalization of MWCNTs and determined the final structures. Thermogravimetric analysis, gel permeation chromatography and UV spectroscopy were performed to evaluate the grafting efficiency of PS that covalently grafted to MWCNTs, and high efficiency of MWCNTs–benzoin as a macro-photoinitiator was also confirmed. Scanning electron microscopy was used to determine the surface morphology of functionalized MWCNTs and MWCNTs–PS.