A Boron-based Adhesion Aid for Efficient Bonding of Silicone Rubber and Epoxy Resin

We improved the adhesion between silicon based insulating materials and epoxy resin composites by adding the adhesion promoter cycloborosiloxane(BSi,cyclo-1,3,3,5,7,7-hexaphenyl-1,5-diboro-3,7-disiloxane).The experimental results show that the addition of BSi in the silicone rubber(SR)system significantly increases the tensile shear strength between BSi and epoxy resin(EP),reaching 309%of the original value.On this basis,the mechanism of BSi to enhance the adhesion effect was discussed.The electron deficient B in BSi attracted the electron rich N and O in EP to enhance the chemical interaction,combined with the interfacial migration behavior in the curing process,to improve the adhesion strength.This study provides the design and synthesis ideas of adhesive aids,and a reference for further exploring the interface mechanism of epoxy resin matrix composites.

Maxillary denture flange and occlusal discrepancies of Vertex ThermoSens in comparison with conventional heat-cured denture base materials

This study was conducted to investigate the maxillary denture bases and occlusal discrepancies using the Vertex Thermosens in comparison with the conventional polymethyl-methacrylate materials. Twenty maxillary denture bases were prepared from the Vertex ThermoSens and a conventional heat-cured denture base materials. Acrylic maxillary second molars were arranged in their respective positions on the ridge. After curing of both types of denture bases, they were deflasked with their respective master casts. Reference points were prepared for measurements of the antero-posterior and cross-arch dimensions at the denture borders using caliper device. Furthermore, the teeth discrepancies were measured between reference points in the ligual aspect of the second maxillary molars. The recorded data was analyzed using SPSS statistical software version 20. The results showed initial shrinkage of both denture bases in the antero-posterior and cross-arch dimensions immediately after decasting. This contraction was compensated gradually during storage in water up to 2 weeks. Regarding the variable time, there was a significant difference between the tested materials. Moreover, the results revealed occlusal discrepancies and shifting of teeth inward immediately after decasting, followed by outward movement after storage in water for 2 weeks. Regarding the variables time and materials, there were significant differences. Both materials exhibited inward shrinkage in the antero-posterior and cross-arch dimensions immediately after decasting. Both denture bases showed inward shifting of teeth immediately after decasting, followed by outward movement after storage in water up to 2 weeks.

Effect of Epoxy Resin on Mechanical Properties of Metakaolin based Geopolymer and Microscopic Analysis

By using NaOH and Na2SiO3 as the activator,the mechanical properties and shrinkage of the geopolymer after incorporation of 0%,10%,20%,and 30% epoxy resin were investigated.The mechanism of epoxy resin toughening metakaolin based geopolymer was analyzed by X-ray diffraction,scanning electron microscopy and Fourier transform infrared spectroscopy.It was shown that with the increases of epoxy resin,the shrinkage performance was obviously improved and the flexural strength increased by 53.5%.The compressive strength of EGP10,EGP20,and EGP30 increased by 49.12%,57.04%,and 65.34% after curing for 28 days,respectively.There were five obvious vibration peaks of 811 cm^-1,1 000 cm^-1,1 050 cm^-1,1 590cm^-1,and 3 400 cm^-1 in the geopolymer and the undisturbed metakaolin.More geopolymer gels were formed in the material and the microstructure was more compact.

Improvement of the electrical resistivity of epoxy resin at elevated temperature by adding a positive temperature coefficient BaTiO3-based compound

The DC electrical resistivity-temperature characteristic is an important property for insulating materials to operate at a high stress level.In order to improve the DC electrical resistivity at elevated temperature in a targeted way,a positive temperature coefficient(PTC)material(Ba Ti O3-based compound(BT60))was selected as the filler in this paper,whose electrical resistivity has a PTC effect when the temperature exceeds its Curie temperature.The BT60 was treated with hydrogen peroxide and(3-Aminopropyl)triethoxysilane.Epoxy composites with different loadings of BT60 fillers(0 wt%,0.5 wt%,and 2 wt%of epoxy)were prepared,denoted as EP-0,EP-0.5,and EP-2.It was shown that BT60 was able to maintain the DC breakdown strength when its loading was less than 2 wt%of epoxy.As the temperature exceeds 60°C,BT60 will compensate for the negative temperature coefficient effect of epoxy resin to some extent.The electrical resistivity of EP-2 was improved by 55%compared with that of neat epoxy at 90°C.It was found that the potential barrier at the grain boundary of BT60 and the deep traps in the interface between BT60 and the epoxy resin hinder the migration of carriers and thus increase the electrical resistivity of epoxy composite.

Preparation of liquefied wood-based resins and their application in molding material

To investigate value in use of liquefied wood-based resin applications in molding material, Chinese fir （Cunninghamia lanceolata） and poplar （Populus tomentosa） wood meal were liquefied in phenol. The reactant was co-condensed with formaldehyde to obtain liquefied wood-based resin. For this paper, we investigated the characterization of the resin and its application in molding material. The result shows that the basic properties of liquefied wood-based resin were satisfactory; the bonding strength of plywood prepared with liquefied Chinese fir and liquefied poplar resin can reach 1.54 and 1.00 MPa, respectively. The compression strengths of the molding material prepared with two kinds of liquefied wood resin were 73.01 and 73.58 MPa, almost the same as that of PF resin molding material. The limiting volume swelling of molding material made with liquefied Chinese resin and liquefied poplar resin were 8.5% and 8.3%, thickness swelling rates of water absorption were 3.3% and 4.2%, and the maximum weight ratios of water absorption were 25.9% and 26.2%, respectively. The soil burial test result shows that the weight loss rate of the molding materials made with liquefied Chinese resin and liquefied poplar resin were 8.3% and 9.1% and that of the PF resin molding material was 7.9%. After the soil internment test, the reduction ratio of compression strength of the two kinds of molding material achieved 16.9% and 17.7%, while that of the PF resin molding material was 15.4%. The test results of wood fungi inoculation on the three surfaces of the molding material indicate the breeding rate of molding material prepared with liquefied Chinese resin and liquefied poplar resin were at level 4 and that of PF resin molding material was at level 1 of the ISO standard.

The Dynamic Tribological Performance of One Certain Resin-based Friction Materials under Different Temperature Conditions

A fixed-point observation method was designed to research the dynamic tribological performance of one certain resin-based friction materials. The friction test was performed through a constant speed friction tester under various temperature conditions. It was found that the dynamic tribological performance of materials has a good consistency with the dynamic evolution of worn surfaces. At lower temperatures, the friction coefficient and wear rate were constant, resulted from the stable worn surfaces. At higher temperatures, the friction coefficient increased gradually, while the wear rate decreased, due to the increasing contact area and Fe concentration. A fade occurred above 250 ℃, which can be explained by the degradation of binders.

Effects of Chairside Polishing and Brushing on SurfaceRoughness of Acrylic Denture Base Resins

The effects of 3 chairside polishing kits and mechanical brushing on the surface roughness of 3 different acrylic denture base resins were compared. Acrylic denture base resins （auto-polymerizing, heat-polymerizing, injected heat-polymerizing resins） were examined after a tungsten carbide bur, and after chairside polishing using 3 polishing kits and pumice. The specimens were subjected to mechanical brushing using a wear tester to simulate 30 000 strokes of brushing. The surface roughness of the acrylic denture base resin specimens was measured using a contact pro-filometer. After the test, the random polished acrylic resins were evaluated by scanning electron mi-croscopy （SEM） and atomic force microscopy （AFM）. Acrylic denture base resins polished using the 3 types of polishing kits had a smoother surface than those finished with the tungsten carbide bur （p〈0.05）. The surface of the resin polished by a TC cutter exceeded the Ra of 0.2 μm （p〈0.05）. The auto-polymerizing resin showed a significantly higher surface roughness than the heat-polymerizing resin and injected heat-polymerizing resin （p〉0.05）. In the case of polishing step wise, there was almost no change in surface roughness after brushing （p〉0.05）.

Effect of Disinfectants on Elastic Modulus, Flexural Strength and Color Stability of Denture Base Resins

Objective: Infection control protocols dictate the disinfection of dentures. There are no products available which are designed for the specific use of disinfecting dentures. The objective of this study was to investigate the impact of chemical disinfectants on elastic modulus, flexural strength and color stability of denture base resins. Methods: 256 specimens from four acrylic denture base resins were manufactured. Two cold-curing denture base resins: PalaXpress (Heraeus Kulzer, Hanau, Germany), Futura Gen (Schuetz Dental, Ro&szlig;bach, Germany) and two heat-curing denture base resins: Paladon 65 (Heraeus Kulzer, Hanau, Germany), FuturAcryl 2000 (Schuetz Dental, Ro&szlig;bach, Germany) were used. Three chemical disinfecting agents were tested: Impresept, D050 Instru-Gen, Stammopur DR. Specimens were stored in distilled water and in chemical disinfecting agents. They were divided randomly into groups. E-Modulus and flexural strength were measured using the three-point bending test. Color changes (ΔE) were determined spectrophotometrically. Results: The disinfection agents showed no significant influence on the E-modulus compared to distilled water (Acrylic vs. distilled water from (Futura Gen) 2688.80 ± 230.78 vs. 2766.60 ± 91.22 MPa to (PalaXpress) 3004.20 ± 26.40 vs. 2851.00 ± 95.23 MPa). Flexural strength after storage in distilled water and disinfection did not differ significantly (Acrylic vs. distilled water from (Paladon65) 27.28 ± 1.30 vs. 28.42 ± 0.84 N/mm2, (p > 0.05) to (PalaXpress) 30.88 ± 0.25 vs. 29.68 ± 0.79 N/mm2, p < 0.001). Disinfection caused a significant color change with Impresept of Paladon 65 (p ≤ 0.001), FuturaAcryl 2000 with Stammopur DR and D 050 Instru-Gen (p ≤ 0.001). Conclusions: The investigated disinfection agents did not influence elastic modulus and flexural strength of denture base resins negatively. ΔE-values were in a range of 1 to 2. Thus, the detected color changes may be marginal. Clinical relevance: Single use disinfections are feasible for acrylic dentures regarding to elastic modulus and flexural strength.

Synthesis of Salmon Calcitonin Analogs Using Fmoc-based Chemistry on MBHA Resins

Peptide analogs of salmon calcitonin (sCT) were synthesized by using Fmoc-based chemistry on MBHA resins. Salmon calcitonin was modified by 1) cysteines at positions 1 and 7 were replaced by valine and alanine respectively to result in open chain analogs, 2) the glycine at position 30 was replaced by alanine, D-alanine and sarcosine respectively, and 3) some residues were deleted besides the above two modifications. A modified two-step deprotection / cleavage procedure, in which a solvent of TFA / TMSBr / thioanisole / EDT / m-cresol combines with HF cleavage, was adopted in SPPS.

MLA-Based Detection of Organic Matter with Iodized Epoxy Resin—An Alternative to Carnauba

Solid organic matter is an important constituent not only in coal, but also in black shale-hosted ore deposits. The reliable recognition and quantification of organic carbon—as well as its microfabric relation to associated inorganic minerals—plays a crucial role in characterization by scanning electron microscopy-based image analysis. However, the use of conventional epoxy resin in the preparation of grain mounts does not allow for recognition of solid organic carbon compounds. In this study we illustrate that the use of iodized epoxy resin readily overcomes this bottleneck. Best results are obtained with an addition of 15 wt% iodoform to the epoxy resin. With process samples of black shale-hosted polymetallic Kupferschiefer-type ore as a case study, it is shown that recognition and quantification of solid organic carbon are easily achieved and that tangible parameters such as particle and grain sizes, association and liberation for ore and gangue minerals can be determined in the presence of solid organic matter. Due to the inherent uncertainty of the exact chemical composition of the kerogen contained in Kupferschiefer, it was not possible to attain exact comparability between chemical Corg assays and assays calculated from MLA data. However, the results are still found to closely agree with one another. The strength of iodized resin lies in its ability to distinguish organic matter with high hydration ratios in addition to the easy integration in sample preparation. It could therefore be an attractive supplement in the analyses of other raw materials containing complex organic-matter.

Evaluation study on properties of a macroporous silica-based CMPO extraction resin to be used forminor actinides separation from high level liquid waste

Basic properties of a silica-based octyl(phenyl)-N,N-diisobutylcarbamoyl-methylphosphine oxide (CMPO) extraction resin (CMPO/SiO2-P) was investigated.Adsorption behavior for some rare earth elements (RE) which are constituents of high level liquid waste (HLLW) and the long-term stability of the extraction resin in nitric acid solution were examined.The CMPO extraction resin was significantly stable in 3 mol·L?1 HNO3 solution at 50oC.Furthermore,the RE(III) were efficiently separated from non-adsorptive fission product (FP) elements such as Sr(II) in a column experiment using a highly nitric acid solution.The separation behaviors of the elements are considered to result from the difference in their adsorption and elution selectivity based on the complex formation with CMPO.There was no strong dependency of RE(III) separation efficiency on feed solution flow rate.Only from the perspectives of the acid-resistant behavior of CMPO extraction resin and the elution kinetics for the metal ions with the extraction resin,the CMPO extraction resin can be used in the modified MAREC process for HLLW partitioning.

呋喃基磷杂菲阻燃剂的合成及在阻燃环氧树脂中的应用

以5-羟甲基糠醛、糠胺、三氯氧磷和9,10-二氢-9-氧杂-10-磷杂菲-10-氧化物(DOPO)为原料合成了一种呋喃基磷杂菲阻燃剂(Furan-2DOPO),并利用傅里叶变换红外光谱(FTIR)、核磁共振波谱(^(1)H NMR和^(31)P NMR)对其结构进行了表征.进一步利用Furan-2DOPO对环氧树脂进行阻燃改性,得到一系列阻燃环氧固化物.考察了Furan-2DOPO的用量对阻燃环氧固化物的力学性能、热稳定性以及阻燃性能的影响.研究结果表明,当Furan-2DOPO的添加量(质量分数)仅为5%时(磷质量分数为0.47%),环氧固化物的氧指数达到31.0%,且能够通过UL-94垂直燃烧V-0级测试.与未改性环氧树脂相比,添加2.5%和5%Furan-2DOPO的环氧固化物的最大热释放速率分别下降了31%和35%.此外,2种添加Furan-2DOPO的环氧固化物的拉伸强度均比未改性环氧树脂提升了约28%.炭层分析结果表明,Furan-2DOPO具有良好的催化成炭性能,有利于减少燃烧过程中可燃性气体的逸出,从而提升阻燃性能.

马来海松基环氧树脂的制备与性能研究

在“双碳”发展战略目标的背景下,为探索绿色环保型生物基环氧树脂在电工设备上的应用前景,本文以可再生资源松香为原料,制备了一种生物基树脂——马来海松基环氧树脂(MPAER)。以甲基六氢邻苯二甲酸酐(MHHPA)为固化剂,对MPAER/MHHPA体系的固化特性、热性能、力学性能和电气性能进行了系统研究,并和商用双酚A二缩水甘油醚(DGEBA)组成的DGEBA/MHHPA体系进行对比。结果表明:MPAER/MHHPA和DGEBA/MHHPA体系的固化反应活性相当,MPAER/MHHPA体系的玻璃化转变温度为112.8℃,其力学性能和电气性能均稍弱于DGEBA/MHHPA体系,其中MPAER/MHHPA体系的电气强度比DGEBA/MHHPA体系低9.4%。但MPAER/MHHPA体系的综合性能仍较好,可以通过对MPAER进行结构优化或者与其他类型的环氧树脂共混来进一步提高其性能。

秸秆液化树脂化产物制备生物沥青及性能分析

针对目前利用废木材、农作物秸秆、牲畜粪便、废油等制得生物油,进而部分或完全取代石油基沥青时路用性能不足的问题,提出了一种采用秸秆液化产物树脂化制木质基酚醛树脂部分取代石油基沥青,开发绿色可持续的生物沥青。首先,对秸秆进行组分分离得到纤维素和木质素,对秸秆及其主要组分分别进行液化,探讨秸秆液化的主要影响因素;其次,将液化产物与甲醛反应合成木质基酚醛树脂WPR,并与苯酚反应所得酚醛树脂PR进行对比分析;最后,将树脂以不同比例掺到基质沥青中制备生物沥青,通过各生物沥青的三大指标及黏度,分析生物沥青的性能。结果表明:秸秆的液化速率主要取决于纤维素的液化速率,其液化反应复杂,反应动力学级数为1.71;由树脂得率及液化产物、WPR、PR的FT-IR谱图分析可知,WPR树脂合成率较高,且比PR具有更好的反应活性;仅掺加液化产物制备的生物沥青性能较差,掺加WPR树脂的生物沥青高温稳定性、低温抗裂性能、抗变形能力及温度稳定性均优于基质沥青。

聚合物基陶瓷化复合材料的研究进展

聚合物基陶瓷化复合材料具有有机高分子材料和无机陶瓷的优异性能,可在高温下变成多孔结构和冲击陶瓷层,陶瓷层可阻碍热量传递,隔离可燃物与氧气的接触,因此具有很好的阻燃和耐火作用,是一种新型耐火和耐高温材料。介绍了聚合物基陶瓷化复合材料的组成及其陶瓷化机理,综述了聚合物基陶瓷化复合材料的分类,包括橡胶类陶瓷化复合材料、乙烯聚合物基陶瓷化复合材料、环氧树脂基陶瓷化复合材料、酚醛树脂基陶瓷化复合材料等。未来的研究重点主要集中在提高陶瓷填料与树脂基体的相容性、制备高效阻燃剂和高效陶瓷化体系的设计上。

提升杂环芳纶复合性能的研究进展

杂环芳纶是指主链中含有芳杂环(通常为苯并咪唑)的一类对位芳纶,其具有轻质、高强高模、高耐热、耐溶剂等优异性能。相比典型的芳纶Ⅱ纤维,杂环芳纶具有更加优异的力学性能,目前在我国的航空航天和防弹防护等领域得到了实际的应用。然而,与其他有机纤维类似,杂环芳纶由于表面惰性,其与树脂的复合性能相对较低,限制了其在先进复合材料领域的应用。本文从杂环芳纶表面改性和结构设计两方面出发,总结近年来提高杂环芳纶复合性能的设计思路、技术手段和研究成果,展望其在先进复合材料应用领域的发展趋势,为有机纤维的界面设计及改善界面粘接性提供帮助和参考。

生物质基厚朴酚和糠醛对酚醛树脂的改性研究

为了减少化石能源的使用,选取生物质基厚朴酚和糠醛取代部分苯酚和甲醛,制备了改性酚醛树脂。通过傅里叶变换红外光谱仪,核磁共振波谱仪对改性酚醛树脂进行表征,考察了改性酚醛树脂的基础性能及固化后的力学性能。结果表明:厚朴酚和糠醛改变了酚醛树脂的分子结构,改性酚醛树脂的黏度和游离酚含量明显降低;经过固化后的改性酚醛树脂拉伸强度、冲击强度、弯曲强度分别提高18.6%、20.4%和24.9%。

微表处用水性树脂基改性乳化沥青流变性能

机场道面微表处技术养护品质依赖于其胶结材料性能,为明确水性树脂聚合物掺量对微表处用改性乳化沥青流变特性的影响,制备了微表处用WER/WPU改性乳化沥青与WER/WPU/EVA改性乳化沥青,借助动态剪切流变试验、线性振幅扫描试验和弯曲梁流变试验,探明了不同水性树脂聚合物掺量下改性乳化沥青高温抗变形能力、中温疲劳性能与低温蠕变特性,对比分析了WER/WPU改性乳化沥青与WER/WPU/EVA改性乳化沥青的流变性能,并与现有研究中改性乳化沥青的抗变形、抗开裂能力进行了对比评价。结果表明:掺加树脂聚合物后乳化沥青材料的高温抗变形能力、中温疲劳寿命以及低温柔韧性得到有效提升,提升幅度随水性树脂聚合物掺量增加而提高;WER/WPU/EVA-15改性乳化沥青高温抗变形性能略优于WER/WPU-15改性乳化沥青,但其疲劳特性与低温抗裂性较WER/WPU-15改性乳化沥青略低。文中所研制的树脂基改性乳化沥青具有显著的先进性。

香草醛衍生含磷席夫碱的合成及与DOPO协效阻燃环氧树脂

本文以苯基磷酰二氯、香草醛和4-氨基苯酚为主要原料,合成了一种含磷席夫碱阻燃剂(PH-VAN-AP),并采用红外光谱、核磁共振氢谱和核磁共振磷谱证明其结构符合预期。将DOPO与PH-VAN-AP作为复配阻燃剂PH/DOPO加入环氧树脂(EP)中,通过垂直燃烧(UL-94)、极限氧指数(LOI)和锥形量热测试(CCT)对其阻燃性能进行了表征,并利用热失重和差示扫描量热分析了环氧树脂的热稳定性、热降解过程及玻璃化转变温度(T_(g))。结果表明,PH/DOPO兼有气相和凝聚相2种阻燃机理,能有效提高EP的燃烧性能。具体而言,当仅添加PH/DOPO至体系的3%(质量分数)时,顺利通过了UL-94测试并达到V-0等级,其LOI由24.7%提高至34.8%。此外,峰值热释放速率(PHRR)和总热释放(THR)分别降低了257 kW/m^(2)和8 MJ/m^(2),材料的残留量提高了6.8%。添加3%的PH/DOPO,环氧树脂的Tg由149.5℃降至148.1℃,变化不大,表明PH-VAN-AP一定程度上改善了由于DOPO加入EP后导致T_(g)下降的问题。