Effect of neutral polymeric bonding agent on tensile mechanical properties and damage evolution of NEPE propellant

Introducing Neutral Polymeric bonding agents(NPBA) into the Nitrate Ester Plasticized Polyether(NEPE)propellant could improve the adhesion between filler/matrix interface, thereby contributing to the development of new generations of the NEPE propellant with better mechanical properties. Therefore,understanding the effects of NPBA on the deformation and damage evolution of the NEPE propellant is fundamental to material design and applications. This paper studies the uniaxial tensile and stress relaxation responses of the NEPE propellant with different amounts of NPBA. The damage evolution in terms of interface debonding is further investigated using a cohesive-zone model(CZM). Experimental results show that the initial modulus and strength of the NEPE propellant increase with the increasing amount of NPBA while the elongation decreases. Meanwhile, the relaxation rate slows down and a higher long-term equilibrium modulus is reached. Experimental and numerical analyses indicate that interface debonding and crack propagation along filler-matrix interface are the dominant damage mechanism for the samples with a low amount of NPBA, while damage localization and crack advancement through the matrix are predominant for the ones with a high amount of NPBA. Finally, crosslinking density tests and simulation results also show that the effect of the bonding agent is interfacial rather than due to the overall crosslinking density change of the binder.

Cytotoxicity of seven recent dentine bonding agents on mouse 3T3 fibroblast cells

Today it is generally accepted that most bonding agents are cytotoxic. In this study the relative cytotoxicity of seven recent dentine bonding agents on mouse 3T3 fibroblast cells were investigated. Materials and Methods. Near-confluent mouse 3T3 fibroblast cells were exposed to Dulbecco Modified Eagle’s Medium containing extractions from the seven different bonding agents. The cell survival rate was then determined using the standard MTT assay. Results. The cell survival rate ranking is: iBond (94%) < Gbond (78%) < Xeno V (71%) < Adper Easy Bond (63%) < Xeno V+ (61%) < Adper Scotchbond SE (33%) < XP Bond (32%). Part A of Adper Scotchbond SE had a survival rate of 35% and part B 38%. These two parts did not differ significantly. Adper Scotchbond SE and XP Bond do not differ significantly. While Xeno V+, Xeno V and Adper Easy Bond do not differ. (p < 5%;Tukey-Kramer Multiple-Comparison Test). Conclusion. All of the tested adhesive bonding agents were cytotoxic with survival rate of 3T3 cells between 94% to 31%. Of the 7 bonding agents tested iBond was found to be only slightly toxic and by far the least toxic. The two bonding agents (XP Bond and Adper Scotchbond SE) containing UDMA plus TEGDMA plus HEMA plus camphorquinone were found to be the most toxic.

Investigation of the role of aziridine bonding agents on the aging of the composite solid rocket propellant(CSRP)

The role of bonding agents on the aging characteristics is one of the important research topics.Aging program of the prepared propellant samples was conducting as follows:Five samples,two free of bonding agents,and three containing an aziridine based bonding agents(MAPO,HX-752,MAT4),four samples based on different bonding and curing agents all were aged at 70 ℃.The prepared bonding agent "MAT4" gave remarkable improvements and resulted in highly stable mechanical properties comparing with HX-752 or MAPO.The selected bonding agents family inhibited the rate of decomposition of the propellants during the aging periods and supported the propellant matrix against decomposition at the elevated temperatures.

Properties of SiC Particulate Preforms Based on Different Pore-forming Agents and Bonding Methods for Making SiC/Al Composites

The preforms with high SiC volume fraction(>50%) were successfully fabricated by two bonding methods. Moreover, the dimensional change, compressive strength, and microstructure of Si C preforms were investigated, and the bonding mechanism among SiC particulates in preforms was also discussed. Results show that, after heating to 1 100 ℃ and holding for 2 h, a uniform and interconnected structure in the SiC preforms can be obtained by using starch, stearic acid, and graphite respectively as the pore-forming agents, which benefi ts the subsequent infi ltration by the molten metals. More neck-like-jointing among SiC particulate by using graphite as the pore-forming agent improves the dimensional accuracy and compressive strength of the preform. Besides, the properties of the preforms by the binder bonding are better than those by the oxidation bonding, which is mainly because the mixed neck-like-jointing and binder at high temperature provide effective bonding together.

Anti-proteolytic capacity and bonding durability of proanthocyanidin-biomodified demineralized dentin matrix

Our previous studies showed that biomodification of demineralized dentin collagen with proanthocyanidin(PA) for a clinically practical duration improves the mechanical properties of the dentin matrix and the immediate resin–dentin bond strength. The present study sought to evaluate the ability of PA biomodification to reduce collagenase-induced biodegradation of demineralized dentin matrix and dentin/adhesive interfaces in a clinically relevant manner. The effects of collagenolytic and gelatinolytic activity on PA-biomodified demineralized dentin matrix were analysed by hydroxyproline assay and gelatin zymography. Then, resin-/dentin-bonded specimens were prepared and challenged with bacterial collagenases. Dentin treated with 2% chlorhexidine and untreated dentin were used as a positive and negative control, respectively. Collagen biodegradation, the microtensile bond strengths of bonded specimens and the micromorphologies of the fractured interfaces were assessed. The results revealed that both collagenolytic and gelatinolytic activity on demineralized dentin were notably inhibited in the PA-biomodified groups, irrespective of PA concentration and biomodification duration. When challenged with exogenous collagenases, PA-biomodified bonded specimens exhibited significantly less biodegradation and maintained higher bond strengths than the untreated control. These results suggest that PA biomodification was effective at inhibiting proteolytic activity on demineralized dentin matrix and at stabilizing the adhesive/dentin interface against enzymatic degradation, is a new concept that has the potential to improve bonding durability.

Super-Bond C&B在口腔临床40年间的应用及特点

背景:Super-Bond C&B自1982年问世以来,经过40年临床病例检验与科研积淀,在口腔多领域各种材料与界面之间的粘接有着广泛的应用场景和市场。目的:就Super-Bond C&B的发展历史、化学成分、粘接机制、临床适应证以及与其他常规树脂水门汀的区别做一综述,以帮助临床医师在口腔各种复杂病例的粘接过程中选择合适的粘接系统。方法:以中文检索词“超级粘接剂、粘接机制;超级粘接剂、化学性质;剪切粘接强度”检索万方数据库、维普数据库及CNKI中国期刊全文数据库,以英文检索词“Super-Bond C&B、MMA/TBB、4-META、Resin、Bond strength、Adhesive、Ceramics”检索PubMed数据库,检索时间范围重点为1962年至2022年7月,最后纳入67篇文献进行综述。结果与结论:Super-Bond C&B作为一种具有良好生物相容性及粘接强度的无填料纯树脂粘接系统,广泛应用于不同口腔修复体的粘固、牙体组织粘接、正畸托槽的粘固、牙周松动牙固定等口腔临床疾病治疗。Super-Bond C&B相比于其他树脂水门汀和其他粘接系统,具有良好的粘接性能、力学性能、生物学相容性、稳定的临床表现以及广泛的临床适用性,因此具有较高的临床应用价值。

Effect of Silane Coupling Agent Concentration on Interfacial Properties of Basalt Fiber Reinforced Composites

The purpose of this study is to investigate the effect of the concentration of silane coupling solution on the tensile strength of basalt fiber and the interfacial properties of basalt fiber reinforced polymer composites.The surface treatment of basalt fibers was carried out using an aqueous alcohol solution method.Basalt fibers were subjected to surface treatment with 3-Methacryloxypropyl trimethoxy silane at 0.5 wt.%,1 wt.%,2 wt.%,4 wt.%and 10 wt.%.The basalt monofilament tensile tests were carried out to investigate the variation in strength with the concentration of the silane coupling agent.The microdroplet test was performed to examine the effect of the concentration of the silane coupling agent on interfacial strength of basalt reinforced polymer composites.The film was formed on the surface of the basalt fiber treated silane coupling agent solution.The tensile strength of basalt fiber increased because the damaged fiber surface was repaired by the firm of silane coupling agent.The firm was effective in not only the surface protection of basalt fiber but also the improvement on the interfacial strength of fiber-matrix interface.However,the surface treatment using the high concentration silane coupling agent solution has an adverse effect on the mechanical properties of the composite materials,because of causing the degradation of the interfacial strength of the composite materials.

蒸压轻质混凝土板专用粘结砂浆的制备与性能研究

采用P·O42.5水泥、粉煤灰、石灰石超细粉、矿粉以及外加剂为原料制备水泥基粘结砂浆。采用正交试验确定水泥基胶凝材料的最优配合比,研究淀粉醚对纤维素醚取代率和膨胀剂对水泥基粘结砂浆的性能影响,并利用XRD和SEM分析水化产物和微观形貌,研究外加剂的作用机理。结果表明,m(水泥)∶m(粉煤灰)∶m(矿粉)∶m(石灰石超细粉)=22∶4∶4∶5时,水泥基胶凝材料的性能最优;淀粉醚适量取代纤维素醚可以增强砂浆保水性,提高砂浆强度,减少收缩;少量膨胀剂可以提高砂浆的早期强度,增加掺量则降低早期强度,提高砂浆后期强度。制备的水泥基粘结砂浆符合JC/T 890—2017《蒸压加气混凝土墙体专用砂浆》的要求。

纳米SiO_(2)界面剂对新旧混凝土界面抗渗性能和微观结构影响研究

采用试验的方法探究了纳米SiO_(2)界面剂对新旧混凝土界面劈裂黏结强度和抗渗性能的影响,其使用形式包括喷洒稀释溶液及作为增强相的砂浆界面剂两种方式,并与整体现浇试件及传统界面凿毛组的抗渗性能进行对比分析.同时,借助扫描电子显微镜(SEM)对不同纳米界面剂的黏结面微观结构进行了探究.最后,从界面强度、抗渗性能和微观机理3方面分析了纳米SiO_(2)界面剂对新旧混凝土界面黏结性能的影响.结果表明:两种纳米SiO_(2)界面剂均能不同程度地提高界面黏结强度及其抗渗性能,其中纳米SiO_(2)砂浆界面剂效果明显优于纳米SiO_(2)溶液组,且两者均存在最优掺量,分别为3.75%和2.5%;随着界面粗糙度的增加,黏结试件渗水高度和相对渗透系数逐渐降低;界面相对渗透系数与劈裂强度呈负相关,且相比于劈裂强度,相对渗透系数对界面缺陷更敏感.微观分析结果表明:纳米SiO_(2)的掺入改变了界面过渡区(ITZ)水化产物数量和C-S-H凝胶形貌,有效抑制了界面孔隙网络贯通,使ITZ微观结构更为致密.

Super-bond加金属舌面背板修复下前牙缺失的临床观察

目的:评价Super-Bond粘结剂加金属舌面背板修复下前牙缺失的临床效果。方法:应用Super-Bond粘结剂加铸造金属舌面背板修复下前牙缺失。结果:40例患者随访24个月。有效30例,显效8例,无效2例,有效率为95%。结论:该方法操作简便,牙体预备量小,修复美观效果好,对松动下前牙有固定作用并能有效恢复咀嚼功能。

固位钉对All-Bond2粘结强度的影响

目的 探讨固位钉对All-Bond 2粘结强度的影响。方法 应用All-Bond 2为粘结剂 ,将 15个离体牙随机分为 3组 ,测试加金属固位钉前后光敏复合树脂粘结离体牙表面的剪切粘结力 ,分析固位钉的作用。结果 实验I组 (不加固位钉 )的剪切粘结力为 2 5 .87+ 5 .10Kgf;实验II组和实验III组是将固位钉攻入牙本质内 ,深度分别为 2mm和 3mm ,其剪切粘结力分别为 :2 5 .77+ 3 .72Kgf及 2 6 .2 6 + 3.14Kgf。经统计学处理 ,三组间无显著性差异。结论 复合树脂与牙齿间的粘结强度与加或不加固位钉无相关性 ;

水下自护混凝土与钢筋握裹力试验研究

随着水下自护混凝土技术的推广和应用,其关键工艺参数水下保护剂浓度对水下自护钢筋混凝土结构性能的影响成为关注的热点。基于水下自护技术,在常用工作浓度范围内,对水下自护混凝土的素混凝土力学性能、混凝土与钢筋握裹力、微观孔隙结构开展了试验研究。试验结果表明:在不同水下保护剂浓度下,水下自护素混凝土抗压强度水陆强度比均超过80%;混凝土与钢筋握裹力水陆强度比约在40%~65%,水下保护剂浓度越高,混凝土与钢筋握裹力水陆强度比越低;混凝土基质区域孔隙率和混凝土与钢筋握裹力存在负相关关系;水下保护剂能够有效提升水下自护混凝土的力学性能,但水下保护剂浓度的提升会对混凝土与钢筋握裹力强度造成不利影响。因此,合理选择水下保护剂浓度并增加钢筋用量是提升水下自护钢筋混凝土工程的可靠性的重要举措。

Synthesis of multifunctional additives for solid propellants:Structure,properties and mechanism

To simplify the composite propellant formulation and address the current issue of the single-functionality present in existing additives,the multi-cyano,amine-based polybutadiene(AEHTPB-CN)was prepared based on AEHTPB by adopting appropriate synthesis strategies.By replacing 10% of HTPB binder in the propellant formulation,it can effectively enhance the interfacial bond strength between the propellant binder matrix and solid fillers(AP(ammonium perchlorate)and RDX(cyclotrimethylene-trinitramine)),the mechanical properties of the HTPB/AP/RDX/Al propellant were superior to blank control propellant with an improvement of 35.4% in tensile strength,62.0% enhancement in elongation at break,and reduce the propellant burn rate by 10.7% with any energy loss.The function mechanism of AEHTPB-CN was systematically elucidated through experiments and computer simulation techniques.The results show that the tertiary amine group in AEHTPB-CN can react with AP to form ammonium ionic bonds,and the hydroxyl and cyano groups can form hydrogen bonding interactions with AP,which enables AEHTPB-CN to be firmly adsorbed on the AP surface through chemical and physical interactions.For RDX,the interfacial bonding effect of AEHTPB-CN is attributed to their ability to form C-H···N≡C weak hydrogen bonding interaction between the cyano group and RDX methylene group.

Interfacial reinforcement of core-shell HMX@energetic polymer composites featuring enhanced thermal and safety performance

The weak interface interaction and solid-solid phase transition have long been a conundrum for 1,3,5,7-tetranitro-1,3,5,7-tetraazacyclooctane(HMX)-based polymer-bonded explosives(PBX).A two-step strategy that involves the pretreatment of HMX to endow—OH groups on the surface via polyalcohol bonding agent modification and in situ coating with nitrate ester-containing polymer,was proposed to address the problem.Two types of energetic polyether—glycidyl azide polymer(GAP)and nitrate modified GAP(GNP)were grafted onto HMX crystal based on isocyanate addition reaction bridged through neutral polymeric bonding agent(NPBA)layer.The morphology and structure of the HMX-based composites were characterized in detail and the core-shell structure was validated.The grafted polymers obviously enhanced the adhesion force between HMX crystals and fluoropolymer(F2314)binder.Due to the interfacial reinforcement among the components,the two HMX-based composites exhibited a remarkable increment of phase transition peak temperature by 10.2°C and 19.6°C with no more than 1.5%shell content,respectively.Furthermore,the impact and friction sensitivity of the composites decreased significantly as a result of the barrier produced by the grafted polymers.These findings will enhance the future prospects for the interface design of energetic composites aiming to solve the weak interface and safety concerns.

造孔剂对陶瓷结合剂CBN砂轮组织结构及性能的影响

为研究不同造孔剂对陶瓷结合剂CBN砂轮组织结构及性能的影响,在一定条件下,制备添加不同造孔剂的陶瓷结合剂CBN砂轮试样,对其进行抗折强度、抗冲击强度和气孔率的分析,并对其进行磨削实验。结果表明:同等条件下,添加玻璃空心球的CBN试条气孔率最高,抗折强度和抗冲击强度下降程度较小,兼顾了强度和锋利性的两方面要求;通过磨削实验得到,当加入体积分数约20%的玻璃空心球时,砂轮磨削时的功率最小,同时能得到粗糙度低、表面质量优异的工件。

不同界面剂对湿接缝混凝土黏结性能影响

为研究界面剂对湿接缝黏结性能的影响,首先通过力学性能试验,确定硅灰水泥净浆界面剂中硅灰的最佳掺量,再通过劈裂抗拉强度试验、三点弯曲试验和抗剪强度试验,探究普通水泥净浆、硅灰最佳掺量下的水泥净浆、环氧树脂作为界面剂时,对湿接缝黏结性能的影响效果。结果表明:硅灰最佳掺量为8%时水泥净浆力学性能最优,从抗拉角度和抗剪角度进行分析,不同界面剂对湿接缝黏结性能的影响,由大到小排序均为:环氧树脂界面剂>掺8%硅灰水泥净浆界面剂>普通水泥净浆界面剂>无界面剂。可见,普通水泥净浆界面剂对湿接缝黏结性能提升较小,而环氧树脂界面剂和掺8%硅灰水泥净浆界面剂对湿接缝黏结性能提升效果较为明显。

有机硅偶联剂在水性丙烯酸酯密封胶中的粘接应用研究

以丙烯酸酯乳液为基础聚合物,以有机硅偶联剂为增粘剂制备了水性丙烯酸酯密封胶,并对其粘接和耐老化性能进行了测试。结果表明:复合硅烷偶联剂(WETLINK78和PN-630)比普通硅烷偶联剂(KH550、KH560、KH570)使得水性丙烯酸密封胶具有对玻璃、铝材、不锈钢更高的粘接强度,分别达到1.58、1.25、1.38 MPa,其粘接破坏均为内聚破坏。复合硅烷偶联剂也使得水性丙烯酸密封胶具有更加优异的储存稳定性,在老化实验中硅羟基不易水解和缩聚,经热老化后依然具有良好的粘接性能。

All—Bond Ⅱ牙本质粘合剂在牙体修复中的应用

作者自1995年5月至9月应用All—Bond Ⅱ粘合剂和复合树脂行牙体修复121例。经一年临床观察All—Bond Ⅱ有较强的粘接力,具有亲水性、能在潮湿的牙面上粘合、符合生理要求,对牙髓刺激较少,但在近髓的窝洞仍需垫底。也可以作为牙本质过敏的脱敏剂。

复合硅烷偶联剂LY-178在硅烷改性聚醚密封胶中的应用

选取多种硅烷偶联剂进行对比与复配,分析了其对密封胶固化速度、力学性能和粘结性能的影响。结果表明,KH-792因双氨基结构提升了固化速度和拉伸强度,而LY-178表现出优异的综合性能;采用LY-178与KH-792复配作为硅烷偶联剂,能够在不影响密封胶力学性能的基础上,显著增强密封胶对多种基材的粘结性能。

树脂锚固剂制备过程中搅拌参数对其主要性能的影响分析

首先通过理论分析得出影响树脂锚固剂主要性能的3种主控因素分别为搅拌时间、速率和温度。然后选取350 mm超速型、350 mm快速型、600 mm中速型3种树脂锚固剂为研究对象,并采用控制变量法进行实验设计。最后通过检测不同制备条件下锚固剂的锚固力大小,确定树脂锚固剂制备过程中的最佳搅拌参数。结果显示,超速型、快速型、中速型三种树脂锚固剂的最佳搅拌时间分别为15、25、35 s,最佳搅拌速度为500、500、600 r/s。18~28℃范围内的搅拌温度对这3种树脂锚固剂的性能影响效果不大。以上结果表明,合理选择和控制搅拌参数,可以使树脂锚固剂具备较高的性能。