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.

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.

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.

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。

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.

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%。

一种性能优异的水性环氧防腐底漆配方研究

通过双酚A型环氧树脂E-51(EP-51)与聚乙二醇4000(PEG-4000)进行开环反应,合成环氧乳化剂,利用相反转技术制备出了一种水性环氧树脂乳液,研究了环氧/活泼氢当量、固化剂体系、防锈颜料、颜料体积浓度(PVC)对水性环氧涂料性能的影响。

混凝土加固施工中的环氧树脂胶改性及效果研究

针对传统混凝土施工中环氧树脂胶质脆韧性不足和高温易流挂的问题,提出通过气相白炭黑(MSD)对传统环氧树脂结构胶进行改性。试验结果表明,在酚醛胺固化剂T-31掺量为15%,聚酰胺固化剂PA掺量为40%,硅烷偶联剂KH-792的掺量为3%,超细石英砂掺量为40%,纳米碳酸钙掺量为20%,MSD掺量为3%;短切碳纤维掺量为6%配比下制备的结构胶性能最佳。14 d压缩强度、拉伸强度、正拉粘接强度和拉伸抗拉强度分别为81、34、5.5和18.5 MPa。表现出良好的阻裂粘接性能,可以在桥梁混凝土加固中发挥重要作用。

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。

基于高岭土增韧环氧树脂水泥基材料的多强度组合指标配比优化法

煅烧高岭土能有效改善环氧树脂水泥基材料的力学性能,实验表明:煅烧高岭土可大大提高环氧树脂水泥基材料的3 d早期抗折、抗压强度,当高岭土掺量为30%时,改性环氧树脂水泥基材料的抗折及抗压强度分别提高了134.28%、106.25%;当高岭土掺量小于30%时,改性环氧树脂水泥基材料具有二次抗折强度,且抗折强度残余率大于50%。根据不同高岭土掺量对改性环氧树脂水泥基材料抗压强度、抗折强度、二次抗折强度的影响规律,提出了适用于不同结构工程受力特点的多强度组合指标配比优化法,获得了考虑二次抗拉强度影响的不同最大拉应力和最大压应力组合条件下最优的高岭土配比,为实际不同结构体不同部位不同受力特征的高岭土改性环氧树脂水泥基材料制备提供了理论依据。

超细纤维合成革透水汽性能的研究进展

超细纤维合成革(简称超纤革)是替代天然皮革的理想材料,但超纤革的透水汽性能与天然皮革相比仍存在差距,有待提升。文章概述了超纤革的制备过程,分析了超纤革的性能及其在透水汽性能方面的不足,并从超纤革的主要组分,即超纤革基布和聚氨酯树脂入手,探讨了超纤革透水汽性能研究的最新进展;总结了对超纤革基布的水解、增加活性基团和亲水剂等改性方法,阐述了对聚氨酯树脂的填料、接枝聚合和共混等改性措施,探讨了对超纤革的后整理改性选项,最后提出了超纤革透水汽性能研究的未来发展方向。

生物基可降解环氧树脂及其可回收碳纤维复合材料的研究进展

环氧树脂是目前应用最为广泛的热固性树脂之一,其固化后会形成不溶、不熔的高度交联的三维网络结构,从而导致树脂及其碳纤维复合材料的降解困难而且难以再加工,造成了严重的资源浪费与环境污染。采用可再生生物质原料制备生物基可降解环氧树脂及其碳纤维复合材料,在缓解能源危机、减轻环境污染和实现资源再利用上具有重要意义。综述了生物基可降解环氧树脂及其可回收碳纤维复合材料的研究进展,主要包括含有热或化学不稳定键的可降解环氧树脂的合成、性能、降解机理及其碳纤维的无损回收,并总结了其优缺点。

成型方向对3D打印口腔义齿基托树脂材料物理性能及力学性能的影响

目的:分析成型方向对打印件的表面特征、弹性模量、挠曲强度及断裂韧性的影响及其与受力方向之间的关系,为口腔义齿基托树脂材料的临床应用提供科学依据和指导。方法:采用3D打印技术使用义齿基托树脂材料打印义齿基托树脂试样,试样形状及尺寸参考目前常规义齿基托材料检测标准。检测物理性能的试样为圆柱体(直径15 mm、厚1 mm),在Z轴的不同角度方向上(0°、45°、90°)进行打印。扫描电镜观察经不同方向打印后试样的表面微观形貌;试样经色稳定仪浸水光照后观察其颜色稳定性;利用粗糙度仪分析试样表面粗糙程度;用维氏硬度计测量硬度。检测力学性能的试样为长方体(检测弹性模量和挠曲强度:长64 mm、宽10 mm、高3.3 mm;检测断裂韧性:长39 mm、高8.0 mm、宽4.0 mm),分为W、H两组,W组以长×宽为底面,平行X、Y轴平面,自下而上沿Z轴开始打印,H组以长×高为底面,平行X、Y轴平面,自下而上沿Z轴开始打印,两组成型角度均分为0°、45°和90°,通过万能力学试验机研究其弹性模量、挠曲强度和断裂韧性。采用SPSS 22.0软件对数据进行统计分析。结果:表面形貌和粗糙度与成型方向密切相关,0°、45°及90°试样之间差异具有统计学意义,0°试样表面最光滑(粗糙度<1μm),45°试样表面最粗糙(粗糙度>3μm)。0°试样硬度最佳[(196.13±0.20)MPa],与90°试样[(186.62±4.81)MPa]比较差异具有统计学意义(P<0.05)。试样的力学性能与打印方向也密切相关,W组45°试样的弹性模量、挠曲强度及断裂韧性与其他方向试样比较均为最高,差异具有统计学意义。弹性模量结果显示,H组中,45°试样弹性模量最高,与0°和90°试样比较差异具有统计学意义(P<0.05);W组中0°及45°试样高于90°试样(P<0.05);且W组0°及45°试样的弹性模量均显著高于H组0°及45°试样(P<0.05)。挠曲强度结果显示,H组各角度试样之间差异无统计学意义,W组中90°试样强度最小,与0°及45°试样之间比较差异具有统计学意义(P<0.05),且W组0°及45°试样的强度均显著高于H组0°及45°试样(P<0.05)。断裂韧性结果显示,H组各角度试样断裂韧性均低于义齿基托材料检测标准规定的1.9 MPa m1/2;W组45°试样最高,与0°及90°试样比较差异具有统计学意义(P<0.05),90°试样断裂韧性低于1.9 MPa m1/2。结论:成型方向为0°的试样在物理性能上相对较优,而45°试样具有最优的力学性能;以长×高为底面沿Z轴不同方向打印的试样(H组)以及以长×宽为底面沿Z轴90°打印的试样(W组90°)的断裂韧性尚不满足临床要求,提示3D打印义齿基托树脂性能受打印方向影响,只有各个方向打印试样的各项性能均满足义齿基托材料检测标准的最低要求,才可用于临床。

香草醛衍生含磷席夫碱阻燃剂的合成及在环氧树脂中的应用

通过苯基磷酰二氯、香草醛和4-氨基苯酚制备一种含磷席夫碱阻燃剂PH-VAN-AP。采用红外光谱、核磁共振氢谱和核磁共振磷谱表征PH-VAN-AP的结构。通过垂直燃烧、极限氧指数和锥形量热测试分析了环氧树脂的阻燃性能。利用热失重和差热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,制备的PH-VAN-AP为预期结构。PH-VAN-AP能抑制环氧树脂的燃烧滴落与烟雾产生,在气相和凝聚相中发挥阻燃作用。当阻燃剂PH-VAN-AP的质量分数为5%时,阻燃环氧树脂的氧指数值从24.7%提高到35.4%,峰值热释放速率(pHRR)、总热释放(THR)及总烟雾释放(TSP)分别降低了165kW/m^(2)、5MJ/m^(2)和1.2m^(2),使其残留量提高9.6%。PH-VAN-AP能够提高环氧树脂的Tg,含5%PH-VAN-AP的环氧树脂的Tg从156.9℃提高到162.9℃。