Structural characteristics and properties of polyurethane modified TDE-85/MeTHPA epoxy resin with interpenetrating polymer networks

Diglycidyl-4,5-epoxycyclohexane-1,2-dicarboxylate(TDE-85)/methyl tetrahydrophthalic anhydride (MeTHPA) epoxy resin was modified with polyurethane(PU) and the interpenetrating polymer networks(IPNs) of PU-modified TDE-85/MeTHPA resin were prepared. The structural characteristics and properties of PU-modified TDE-85/MeTHPA resin were investigated by Fourier transform infrared(FTIR) spectrum,emission scanning electron microscopy(SEM) and thermogravimetry(TG). The results indicate that epoxy polymer network (Ⅰ) and polyurethane polymer network (Ⅱ) of the modified resin can be obtained and the networks (Ⅰ) and (Ⅱ) interpenetrate and tangle highly each other at the phase interface. The micro morphology presents heterogeneous structure. The integrative properties of PU-modified TDE-85/MeTHPA epoxy resin are improved obviously. The PU-modified TDE-85/ MeTHPA resin's tensile strength reaches 69.39 MPa,the impact strength reaches 23.56 kJ/m,the temperature for the system to lose 1% mass (t1%) is 300 ℃,and that for the system to lose 50% mass (t50%) is 378 ℃. Compared with those of TDE-85/MeTHPA resin,the tensile strength,impact strength,t1% and t50% of the PU-modified resin increases by 48%,115%,30 ℃,11 ℃,respectively. The PU-modified TDE-85/MeTHPA resin has the structure characteristics and properties of interpenetrating polymer networks.

Synthesis and Characterization of Polyurethane and Epoxy Resin Interpenetrating Polymer Network

A series of Polyurethane (PU)/bisphenol A based Epoxy Resin(EP) Interpenetrating Polymer Networks(IPN) were synthesized and characterized by SEM, DSC, TGA and DMTA. It was found that IPN shows the best compatibility and damping properties when the ratio of PU/EP is 80 to 20. The results show that chain-extender and higher molecular weight of PPG are able to improve the properties of compatibility, damping and thermal properties.

A novel chain-extended urea containing hyperbranched polymer used as toughening modifier for epoxy resin

A new kind of reactive toughening accelerator for epoxy resin, amine-teminated hyperbranched polymer (H2O-NMe2) was synthesized and characterized by FT-IR spectroscopy. Dynamic mechanical analysis (DMA) was used to study the glass transition temperature (Tg), loss factor (tanδ) and activation energy (Ea) by using multiplexing frequency. The results show that the Ea at glassy relaxation process of modified system is about 70-80 kJ/mol higher than that of unmodified system, and the high modulus and good thermal properties are still maintained.

Durability Testing of Composite Aerospace Materials Based on a New Polymer Carbon Fiber-Reinforced Epoxy Resin

In this study,the durability of a new polymer carbonfiber-reinforced epoxy resin used to produce composite material in the aerospacefield is investigated through analysis of the corrosion phenomena occurring at the microscopic scale,and the related infrared spectra and thermal properties.It is found that light and heat can con-tribute to the aging process.In particular,the longitudinal tensile strength displays a non-monotonic trend,i.e.,itfirst increases and then decreases over time.By contrast,the longitudinal compressive and inter-laminar shear strengths do not show significant changes.It is also shown that the inter-laminar shear strength of carbonfiber/epoxy resin composites with inter-laminar hybrid structure is better than that of pure carbonfiber materials.The related resistance to corrosion can be improved by more than 41%.

Polybutylacrylate/poly(methyl methacrylate) Core-Shell Elastic Particles as Epoxy Resin Toughener: Part I Design and Preparation

Polybutylacrylate (PBA)/poly(methyl methacrylate) (PMMA) core-shell elastic particles (CSEP), whose rubbery core diameter ranged from 0.08 μm to 1.38μm, were synthesized by using conventional emulsion polymerization, multi-step emulsion polymerization, and soapless polymerization. Allyl methacylate (ALMA) and ethylene glycol dimethacrylate (EGDMA) were selected as crosslinking reagents for core polymerization. Methacrylic acid (MAA) was used as functional co-monomer with methyl methacrylate as shell component. The content of vinyl groups in PBA rubbery core increased with the amount of crosslinking reagents. The core-shell ratio affected great on the morphology of the complex particles. Furthermore, the amounts of carboxyl on the surface of core-shell particles, copolymerized with acrylic acid, were determined by potentiometric titration. Results showed that methylacrylic acid was distributed mostly on the surface of particles.

Research on Improving the Thermal Conductivity of Epoxy Resin with Flexible Assisted Rigid Groups

Epoxy resins are cross-linked polymeric materials with typically low thermal conductivity.Currently,the introduction of rigid groups into epoxy resins is the main method to improve their intrinsic thermal conductivity.The researchers explored the relationship between the flexible chains of epoxy monomers and the thermal conductivity of the modified epoxy resins(MEP).The effect of flexible chain length on the introduction of rigid groups into the cross-linked structure of epoxy is worth investigating,which is of great significance for the improvement of thermal conductivity of polymers and related theories.We prepared a small molecule liquid crystal(SMLC)containing a long flexible chain via a simple synthesis reaction,and introduced rigid mesocrystalline units into the epoxy resin via a curing reaction.During high-temperature curing,the introduced mesocrystalline units underwent orientational stacking and were immobilized within the polymer.XRD and TGA tests showed that the ordering within the modified epoxy resin was increased,which improved the thermal conductivity of the epoxy resin.Crucially,during the above process,the flexible chains of SMLC provide space for the biphenyl groups to align and therefore affect the thermal conductivity of the MEP.Specifically,the MEP-Ⅵcured with SMLC-Ⅵcontaining six carbon atoms in the flexible chain has the highest thermal conductivity of 0.40W·m^(-1)·K^(-1),which is 125%of the thermal conductivity of SMLC-IV of 0.32 W·m^(-1)·K^(-1),111%of the thermal conductivity of SMLC-Ⅷof 0.36W·m^(-1)·K^(-1),and 182%of the thermal conductivity of pure epoxy of 0.22 W·m^(-1)·K^(-1).The introduction of appropriate length flexible chains for SMLC promotes the stacking of rigid groups within the resin while reducing the occurrence of chain folding.This study will provide new ideas for the enhancement of thermal conductivity of cross-linked polymeric materials.

High Impact Resistance Epoxy Resins by Incorporation of Quadruply Hydrogen Bonded Supramolecular Polymers

A bisphenol A based epoxy was incorporated with a quadruply hydrogen bonded supramolecular polymer as a toughening agent to prepare a composite epoxy resin with higher impact resistance. The supramolecular polymer comprising poly-（propylene glycol） bis（2-aminopropyl） ether chains and 2-ureido-4[1H]-pyrimidinone moieties（UPy） self-assembled into spherical domains with sizes of 300 nm to 600 nm in diameter by micro phase separation in bulk epoxy matrixes. A significant improvement of 300% in impact resistance of the supramolecular polymer incorporated epoxy resin was obtained when the content of supramolecular polymer was 10 wt%. Tensile tests showed that the mechanical properties of the modified epoxy resin containing the hydrogen-bonded supramolecular polymers are also improved compared with those of the neat epoxy resin.

PREPARATION OF MICROGEL-EPOXY RESIN TWO-PHASE POLYMERS BY IN SITU POLYMERIZATION~*

Microgel-epoxy resin two-phase polymers were prepared by in situ copolymerization of ethylenic monomers with unsaturated polyesters. The choice of monomers and the effect of monomer concentration on microgel particle size were discussed. Agglomeration of particles played a significant role in the early stage of polymerization. The microgel dispersion in epoxy resin was stable after the finish of polymerization. Upon curing the particles remained well dispersed.

Epoxy Methacrylate Resin as Binder Polymer for Black Negative-Tone Photoresists

Epoxy acrylate (EA) resin, which originates from epoxides, has long been served as a photocurable coating and adhesive material owing to its double bonds. Specifically, alkaline-developable EA resins can be used as a binder polymer in negative-tone photoresists. In this work, we synthesized a series of acidic polyester-type epoxy methacrylate resins, characterized the intermediates and products, and tested their performance as a binder polymer for the photolithographic micro-patterning of the pixel-defining layer on organic light-emitting diodes in comparison to a widely used commercial binder polymer. Copolymer-type binder polymer BP-2-2 was produced excellent patterning with no residue due to its high compatibility with the black mill base.

Atmospheric pressure plasma jet deposition of TiO_(2)layer on alumina/epoxy to improve electrical properties

In gas-insulated lines,basin-insulators can accumulate charge under non-uniform electric fields,distorting the field distribution and potentially causing surface flashover,which threatens the stability of power systems.In this study,Atmospheric Pressure Plasma Jet(APPJ)technology was used to deposit TiO_(2)on the surface of alumina/epoxy(Al_(2)O_(3)/EP)composites.The impact of deposition of TiO_(2)layer on the surface morphology and chemical composition of Al_(2)O_(3)/EP was studied using testing methods such as Scanning Electron Microscope,X-ray photoelectron spectroscopy,Fourier Transform Infrared Spectrometer,and Energy Dispersive Spectrometer.It was found that APPJ creates a dense,rough Ti-O layer on the Al_(2)O_(3)/EP surface,which bonds tightly with the substrate.The efficacy of APPJ was found to depend on processing time,with optimal results observed at 3 min,DC and AC flashover voltages increased by 29.6% and 15.7%,respectively.TiO_(2)layer enhances the conductivity of the resin and shallows trap levels.Through the synergistic effects of various factors,surface charges are efficiently dissipated and evenly distributed.This study not only reveals the physicochemical process of TiO_(2)deposition via APPJ but also integrates surface characteristics with electrical performance.The findings offer a new strategy to enhance surface flashover voltage and ensure equipment safety.

STUDIES ON APPARENT KINETICS AND RHEOLOGICAL BEHAVIOR OF EPOXY/ACRYLATE IPNS AS VACUUM PRESSURE IMPREGNATION RESINS

The apparent kinetics and cure behavior of novel interpenetrating polymer networks(IPNs) based on cycloaliphatic epoxy resin(CER) and tri-functional acrylate have been investigated by means of differential scanning calorimetry(DSC) and Fourier transform infrared spectroscopy(FT-IR).The results of DSC measurements show that the curing reaction of the TMPTMA component is much earlier than that of the CER component,which can lead to the formation of the IPNs.In contrast to neat anhydride-CER system,the anhydri...

Simultaneously Enhanced Cryogenic Tensile Strength,Ductility and Impact Resistance of Epoxy Resins by Polyethylene Glycol

Rubbers have been well accepted for modifying brittle epoxies but rubber modified epoxies usually posses lowered tensile strength though enhanced ductility and fracture resistance. In this work, a polyethylene glycol （PEG-4000） is used to modify diglycidyl ether of bisphenol A/methyltetrahydrophthalic anhydride system for enhancing cryogenic tensile strength, ductility and impact resistance. The results display that the cryogenic tensile strength, ductility （failure strain） and fracture resistance （impact strength） are all enhanced for the modified epoxy system at proper PEG contents. The maximum tensile strength （127.8 MPa） at the cryogenic temperature （77 K） with an improvement of 30.1% is observed for the modified system with the 15 wt% PEG content. The ductility and impact resistance at both room temperature and cryogenic temperature are all improved for the modified epoxy system with proper PEG-4000 contents. These observations are explained by the positron annihilation lifetime spectroscopy results and scanning electron microscopy results. Moreover, the glass transition temperature decreases slightly with increasing PEG content.

GO/ZIF-67/水性环氧复合涂层的制备及防腐性能

针对氧化石墨烯(GO)无自修复性能和沸石类金属有机框架(MOFs)聚合物的腐蚀介质屏蔽性能较弱等实际问题,将具有主被动协同防腐作用的GO/MOFs复合纳米颗粒作为防腐填料,加到水性环氧树脂涂层(WEP)中从而提升防腐性能。通过微观形貌观察、电化学阻抗谱(EIS)测试和盐水浸泡实验对涂层的附着力和防腐性能进行评价。结果表明:复合纳米涂层的吸水率比纯WEP涂层降低6%。在3.5%盐水中浸泡7 d后,复合纳米填料的添加量达到0.3%时,复合涂层的阻抗模量仍能保持1.9×10^(8)Ω·cm^(2),表现出优异的防腐性能。

环氧树脂自润滑滑动轴承摩擦磨损性能及其仿真分析

在环氧树脂(EP)中加入一定量的r-GO和不同比例的TiO_(2),研究其对EP材料摩擦磨损性能的影响,并基于滑动轴承接触理论,利用ABAQUS有限元软件对添加r-GO/TiO_(2)/EP自润滑层的滑动轴承进行仿真分析,结果表明,加入r-GO或r-GO/TiO_(2)能显著改善EP材料的摩擦学性能,TiO_(2)质量分数为30%的r-GO/TiO_(2)/EP复合材料的摩擦磨损性能最佳;r-GO/TiO_(2)/EP自润滑层的引入能改善轴承的应力和应变分布。

PREPARATION AND PHOTOSENSITIVITY OF WATER SOLUBLE PHENOLIC RESINS CONTAINING ACRYLOYL AND QUATERNARY AMMONIUM CHLORIDE GROUPS

New water soluble and photocrosslinkable prepolymers containing acrylate and quaternary ammonium salt groups were synthesized from epoxy phenolic resin via ring-opening reaction with acrylic acid and with aqueous solution of triethylamine hydrochloride successively. The second reaction needs no phase transfer catalyst to accelerate, since the product formed can act as a phase transfer catalyst. The prepolymer obtained contains both photocrosslinkable acrylate groups and hydrophilic quaternary ammonium salt groups. Optimum conditions for these reactions were studied. The photosensitivity of the prepolymer was also investigated. The effects of different photoinitiators, different crosslinkable diluent monomers and amine accelerator on the photosensitivity of the prepolymer were compared. The photoinitiator of hydrogen abstraction type is still effective without using amine or alcohol as accelerator, because the prepolymer contains a H beside the OH groups formed in the ring-opening reactions.

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。

Fabrication and Characterization of Glass Fiber with SiC Reinforced Polymer Composites

Glass Fiber Reinforced Polymeric (GFRP) Composites are most commonly used as bumpers for vehicles, electrical equipment panels, and medical devices enclosures. These materials are also widely used for structural applications in aerospace, automotive, and in providing alternatives to traditional metallic materials. The paper fabricated epoxy and polyester resin composites by using silicon carbide in various proportions along with GFRP. The hand lay-up technique was used to fabricate the laminates. To determine the properties of fabricated composites, the tensile, impact, and flexural tests were conducted. This method of fabrication was very simple and cost-effective. Their mechanical properties like yield strength, yield strain, Young’s modulus, flexural modulus, and impact energy were investigated. The mechanical properties of the GFRP composites were also compared with the fiber volume fraction. The fiber volume fraction plays a major role in the mechanical properties of GFRP composites. Young’s modulus and tensile strength of fabricated composites were modelled and compared with measured values. The results show that composites with epoxy resin demonstrate higher strength and modulus compared to composites with polyester resin.

水性环氧树脂改性的建筑结构密封胶缓凝性能研究

为研究水性环氧树脂建筑结构密封胶缓凝性能,选用水性环氧树脂、水性环氧树脂固化剂、MS聚合物、硅烷偶联剂、纳米碳酸钙以及不同填料等试剂,以MS聚合物质量为标准设定试剂比例,分别制备A组分与B组分,将2组分依照1∶1质量比混合配比,由此获取不同配比条件下的改性密封胶样本。结果显示,在偶联剂用量达到2%以上时,密封胶样本的适用期符合建筑结构密封胶应用的适用期标准;水性环氧树脂用量为25%,密封胶样本硬度最优;当密封胶样本内不同填料质量比达到3.4∶20∶66∶16时,密封胶样本不会发生流淌现象;不同MS聚合物具有不同特征。

纳米颗粒填充玻璃纤维增强环氧树脂复合材料的力学性能

为探究纳米颗粒[纳米氧化铁(NFe)、纳米二氧化硅(NS)、多壁碳纳米管(MWCNT)]填充玻璃纤维增强环氧树脂复合材料(GFRP)的力学性能,对纳米颗粒质量分数分别为0.1%、0.2%、0.5%、1.0%的纳米颗粒/GFRP材料开展了拉伸、压缩、弯曲及冲击力学性能试验,并结合扫描电镜(SEM)分析了纳米颗粒的种类及质量分数对试件力学性能的影响规律。结果表明,随着纳米颗粒质量分数的增加,试件拉伸强度均先增大后降低,纳米颗粒的良好分散性及与树脂间的黏聚力能够提升试件的拉伸强度,但过量纳米颗粒的掺入会形成积聚现象,使得试件拉伸强度降低。相较于GFRP试件,掺入纳米颗粒的质量分数为0.1%、0.2%、0.5%和1.0%时,MWCNT/GFRP抗压强度的增幅分别为25.31%、36.04%、26.84%和27.25%,弯曲强度的增幅分别为58.74%、63.21%、40.89%及43.11%,纳米颗粒的掺入使得试件抗压强度、弯曲强度、冲击强度均得到改善,颗粒种类及质量分数的不同使得试件力学性能提升效果存在差异。SEM试验结果表明,外荷载作用下纤维出现断裂、分层现象,纤维与纳米颗粒间存在的摩擦效应增强其力学性能,颗粒的积聚使得试件力学性能降低。

环氧树脂混凝土装配式桁架下弦K型节点力学试验及有限元分析

通过静力试验研究了环氧树脂混凝土装配式桁架下弦K型节点的破坏形态、承载能力和节点板的应力与应变分布情况,并进行了有限元模拟分析。结果表明:环氧树脂混凝土下弦K型节点在下弦杆靠近节点板的两侧出现5条竖直裂缝,最终节点板左侧下弦杆处的竖直裂缝前后贯通,弦杆发生拉弯破坏,节点的极限承载力为421.5 kN;有限元模拟结果与试验结果吻合较好,验证了有限元模拟的可靠性。