Thermal,mechanical, and morphological properties of soybean oil-based polyurethane/epoxy resin interpenetrating polymer networks (IPNs)

A series of interpenetrating polymer networks (IPNs) based on epoxy (EP) resin and polyurethane (PU) prepolymer derived from soybean oil-based polyols with different mass ratios were synthesized. The structure, thermal properties, damping properties, tensile properties, and morphology of soybean oil-based PU/EP IPNs were characterized by Fourier-transform infrared spectroscopy, differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), universal test machine, and scanning electron microscopy (SEM). DSC and DMA results show that the glass transition temperature of the soybean oil-based PU/EP IPN decreases with the increase of PU prepolymer contents. Soybean oil-based PU/EP IPNs have better damping properties than that of the pure epoxy resin. The tensile strength and modulus of PU/EP IPNs decrease, while elongation at break increases with the increase of PU prepolymer contents. SEM observations reveal that phase separation appears in PU/EP IPNs with higher PU prepolymer contents.     

EP-g-PU IPN结构阻尼材料

采用-NCO封端的聚氧酯(PU)预聚物,制备了环氧树脂-聚氨酯互穿网络(EP-g-PU IPN);通过添加受阻酚四[β-(3,5-二叔丁基-4-羟基苯基)丙酸]季戊四醇(AO-60)制备了AO-60/EP-g-PU IPN.通过FT-IR、DMA、SEM分别研究了改性分子链的基团变化、改性体系的动态性能及断裂面的形态,...     

Effects of organophilic montmorillonite on hydrogen bonding, free volume and glass transition temperature of epoxy resin/polyurethane interpenetrating polymer networks

Epoxy resin nanocomposites containing organophilic montmorillonite (oM) and polyurethane were prepared by adding oM to interpenetrating polymer networks (IPNs) of epoxy resin and polyurethane (EP/PU). The dispersion degree of oM in EP/PU matrix was characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). Fourier transform infrared spectrometry (FT-IR) showed that strong interactions existed between oM and EP/PU matrix, and oM had some effect on hydrogen bonding of these EP/PU IPNs nanocomposites. Positron annihilation spectroscopy (PALS) and differential scanning calorimetry (DSC) measurements were used to investigate the effect of oM and PU contents on free volume and glass transition temperature (T_g) of these nanocomposites. The PALS and DSC results clearly showed that the presence of oM led to a decrease in the total fractional free volume, which was consistent with increasing T_g upon addition of oM, ascribed to increasing hydrogen bonding in interfacial regions of oM and EP/PU matrix and enhancing the miscibility between EP phase and PU phase. In addition, with increasing PU content, the total fractional free volume increased, corresponding to decreasing T_g.     

SYNTHESIS, CHARACTERIZATION AND PROPERTIES OF ORGANOCLAY-MODIFIED POLYSULFONE/EPOXY INTERPENETRATING POLYMER NETWORK NANOCOMPOSITES

Organoclay-modified hydroxylterminated polysulfone (PSF)/epoxy interpenetrating network nanocomposites (oM-PSF/EP nanocomposites) were prepared by adding organophilic montmorillonite (oMMT) to interpenetrating polymer networks (IPNs) of polysulfone and epoxy resin (PSF/EP) using diaminodiphenylmethane (DDM) as curing agent.The mechanical properties like tensile strength,tensile modulus,flexural strength,flexural modulus and impact properties of the nanocomposites were studied as per ASTM standards.Differ...     

Mechanical and thermal properties of attapulgite clay reinforced polymethylmethacrylate nanocomposites

To investigate the dispersion and nanofillers' interaction of rod‐like silicates (attapulgite, ATT) in the polymethylmethacrylate (PMMA) matrix, a novel in situ modification of ATT by toluene‐2,4‐di‐isocyanate (TDI) using mechanical mixing was exploited, which resulted in homogeneous dispersion and rod‐like texture of ATT nanorods. As a consequence, organo‐modified ATT/PMMA nanocomposites were prepared, which provided prominent improvements in strength, toughness, and thermal stability. High grafting efficiency of TDI on ATT surface was confirmed by FTIR spectra and SEM observations. The uniform dispersion of in situ TDI modified ATT nanorods in the PMMA which was clearly visible in the TEM micrographs, influenced the mechanical and thermal properties of the nanocomposites. The fibrous nanoparticles significantly confined the segmental motion, causing a 13.20°C increase in the glass transition temperature of 2 wt% in situ TDI modified ATT/PMMA nanocomposites. But at higher loadings little or no differences were observed for the reinforcement benefits provided by the in situ TDI modified ATT clay. By comparison, pre‐treated ATT clay severely fractured during mechanical mixing and showed little reinforcement benefits. Copyright © 2010 John Wiley & Sons, Ltd.     

Preparation and characterization of waterborne polyurethane/attapulgite nanocomposites

In this paper, waterbrone polyurethane (WPU)/attapulgite (AT) nanocomposites have been prepared by direct emulsion blending. The WPU was synthesized from poly(tetramethylene glycol), 4,4-diphenylmethane diisocyanate, dimethylol butanic acid, and neutralized by triethylamine. SEM examination of fractured surfaces showed that AT particles were irregularly dispersed in the WPU matrix. FTIR analysis suggested no major chemical structural changed in the presence of a small amount of AT. DMA results showed that the storage modulus of WPU/AT nanocomposites was increased and the glass transition temperatures of both soft and hard segments shifted to higher temperature compared to the pristine WPU. Thermal resistance of the samples measured by TGA was improved with the addition of AT. The mechanical properties of the nanocomposites, examined by tensile tests, showed higher tensile strength and elongation at break than that of the pristine WPU.     

聚氨酯互穿聚合物网络阻尼性能研究进展

介绍了聚氨酯互穿聚合物网络（ＰＵ ＩＰＮ）作为阻尼材料的研究进展,分别讨论了聚氨酯（ＰＵ）／环氧树脂（ＥＰ）ＩＰＮ和ＰＵ／乙烯基聚合物ＩＰＮ的阻尼性,以及影响阻尼性能的因素,并比较了不同类型的ＰＵ ＩＰＮ的优缺点及新的可能的探讨方向。     

A study on the glass transition behavior and morphology of semi-interpenetrating polymer networks

The epoxy resin/polyurethane semi-IPN was prepared and the glass transition behavior of the semi-IPN was discussed with DSC and DMA methods. The results show that the two glass transition temperatures (T_g) referring to epoxy resin and polyurethane respectively get closer. Between the two T_g there exists another T_g related to the interface between the two polymers. SEM indicates that this semi-IPN has a two-phase continuous structure which changes with different weight compositions. This is also proved by testing the Young's modulus. It is found that the IPN system has a cellular structure. Comparatively, the compatibility between the two polymers is the best when the weight ratio of EP/PU is 70/30. © 1996 John Wiley & Sons, Inc.     

聚氨酯/环氧树脂互穿网络硬质泡沫塑料反应过程和微观结构

聚氨酯／环氧树脂互穿网络(PU／EPIPN)硬泡中异氰酸根的消耗速度较纯PU硬泡高，是由于环氧树脂的固化荆同时也是异氰酸根反应的催化荆。而PU／EP IPN硬泡中环氧基的反应速度和反应程度均较纯EP网络低，归因于互穿网络对基团扩散的阻碍。在互穿网络硬泡形成过程中，存在环氧开环中所新产生的羟基与异氰酸根的反应、大分子多元醇中羟基与环氧基的反应以及异氰酸根与环氧基形成嗯唑烷酮的反应三种形成网络间的化学键的途径。同时由于PU／EPIPN硬泡高度的交联，使得IPN硬泡中两个网络具有良好的相容性。动态力学性能表明所有IPN样品都只有一个玻璃化温度。透射电镜表明IPN样品无明显的相界面。     

Thermal and dynamic mechanical properties of epoxy resin/poly(urethane‐imide)/polyhedral oligomeric silsesquioxane nanocomposites

Linear isocyanate‐terminated poly(urethane‐imide) (PUI) with combination of the advantages of polyurethane and polyimide was directly synthesized by the reaction between polyurethane prepolymer and pyromellitic dianhydride (PMDA). Then octaaminophenyl polyhedral oligomeric silsesquioxane (OapPOSS) and PUI were incorporated into the epoxy resin (EP) to prepare a series of EP/PUI/POSS organic–inorganic nanocomposites for the purpose of simultaneously improving the heat resistance and toughness of the epoxy resin. Their thermal degradation behavior, dynamic mechanical properties, and morphology were studied with thermal gravimetric analysis (TGA), dynamic mechanical analysis (DMA), and transmission electron microscope (TEM). The results showed that the thermal stability and mechanical modulus was greatly improved with the addition of PUI and POSS. Moreover, the EP/PUI/POSS nanocomposites had lower glass transition temperatures. The TEM results revealed that POSS molecules could self assemble into strip domain which could switch to uniform dispersion with increasing the content of POSS. All the results could be ascribed to synergistic effect of PUI and POSS on the epoxy resin matrix. Copyright © 2010 John Wiley & Sons, Ltd.     

聚醚聚氨酯/环氧树脂互穿网络高聚物的研究(Ⅰ)

互穿网络高聚物(IPN)是两种或多种交联聚合物的共混体。由于两种聚合物网络相互贯穿和缠结,链节间的永久锁结产生强迫互容,使不同聚合物达到最紧密混合,最大限度地控制多相体系的相分离,IPN材料显示不寻常的耐热,耐溶剂和高强度等特点,远远超过其聚合物本身的性能。在IPN中,两网络相互贯穿程度越高,相分离越低,这主要取决于构成聚合物本身的相容性和最终网络结合方式。本文通过改变组     

Damping characteristics and mechanical properties of silica filled PUR/PEMA simultaneous interpenetrating polymer networks

Simultaneous polyurethane/poly(ethyl methacrylate) interpenetrating polymer network was synthesised by the one-shot route at the 70PUR/30PEMA composition ratio. This semi-miscible IPN exhibited its potential as a material for damping application by a broad loss factor (tan δ) ? 0.3 spanning a temperature range of 132 °C. The TEM micrographs revealed a multiphase morphology where the mixing between the two polymers was extensive. Incorporation of silica was made in order to study the effects of filler on the IPN properties in terms of glass transition temperature, dynamic mechanical properties, and mechanical and thermal properties. Dynamic mechanical thermal analysis indicated that the filler enhanced the damping ability of the IPN at certain temperature range. Furthermore, the addition of filler resulted in improved material strength.     

Improving Damping Properties and Thermal Stability of Epoxy/Polyurethane Grafted Copolymer by Adding Glycidyl POSS

Modified castor oil-based epoxy resin (EP)/polyurethane (PU) grafted copolymer by glycidyl polyhedral oligomeric silsesquioxane (glycidyl POSS) was synthesized. The damping properties, thermal stability, mechanical properties and morphology of the grafted copolymer modified by glycidyl POSS were studied systematically. The results revealed that the incorporation of glycidyl POSS improved the damping performance evidently and broadened damping temperature range, especially when the glycidyl POSS content was0.2%–1%. At the same time, there was a slight increase in thermal stability with the increase of POSS content. The tensile properties changed with the change of the copolymer's Tg, decreased at low POSS contents and increased at high POSS contents. This modified copolymer has the potential to be used as film damping material or constrained damping layer.     

丁腈羟聚氨酯/聚环氧树脂互穿网络高聚物的研究

本文用同步法合成了丁腈羟聚氨酯/聚环氧树脂(PU/PE)体系的互穿网络高聚物(IPN),研究了各种因素对其形态和玻璃化转变行为的影响,并用扭辫及扭摆(TPA)在-100℃-+150℃温度区间内,测试全部试样的动态力学谱。结果表明,PU/PE是不相容体系,在电镜片上呈现细胞状结构(400-800Å)。由于两组份网络互穿,发生“强迫互容”,使T_g内移,通过调整组份比和加不同扩链剂等能提高阻尼值,加宽T_g转变区。     

聚氨酯/聚苯乙烯互穿聚合物网络的研究

互穿聚合物网络形态和力学性能的研究已有报道^[1～3],但有关合成过程中分子量变化形态和性能的影响研究甚少。本文在动力学研究的基础上^[4],用GPC、DSC和Instron万能机研究了聚氨酯/聚苯乙烯互穿聚合物网络(PU/PSt-IPN)的分子量,玻璃化转变温度和力能,考察了分子量与相分离点之间的关系。     

Tribological performance and thermal behavior of epoxy resin nanocomposites containing polyurethane and organoclay

A series of epoxy resin nanocomposites modified by polyurethane and organically modified montmorillonite was prepared by effectively dispersing the organically modified montmorillonite in interpenetrating polymer networks (IPNs) of epoxy and polyurethane via the sequential polymeric technique and in situ polymerization. The tribological performance of the resultant EP/PU nanocomposites was investigated by a pin‐on‐disc tester, and the results showed that adding polyurethane and organically modified clay to the EP matrix had a synergistic effect on improving tribological performance of EP/PU nanocomposites. The morphologies of the worn surface were studied by scanning electron microscopy (SEM) observations, and the results indicated that the mechanism of improving tribological performance of EP/PU nanocomposites was different from that of pure EP or pure EP/PU IPNs. The thermal behavior of these nanocomposites was also investigated by thermogravimeric analysis (TGA), and the results indicated that adding organically modified clay to the matrix remedied the deterioration of the thermal degradation temperature of the interpenetrating networks. Copyright © 2008 John Wiley & Sons, Ltd.     

甲基丙烯酸镁增强氢化丁腈橡胶的结构与形态和性能

用不同份量的甲基丙烯酸镁(MgMA)作增强剂,过氧化二异丙苯(DCP)作硫化剂,通过混炼和硫化过程的原位聚合制备了氢化丁腈橡胶/聚甲基丙烯酸镁(HNBR/PMgMA)纳米复合材料,用XRD、FTIR1、3C-NMR、SEM、TEM、DMA和交联密度分析等方法研究了其结构、形态和性能,并阐述了MgMA改性HNBR的相关机理.结果表明,MgMA在混炼过程中粒径明显变小,部分达到纳米级.硫化过程中发生原位自由基聚合,并部分接枝到HNBR分子链上,HNBR硫化胶和PMgMA有可能形成接枝互穿聚合物网络(接枝IPN).随着MgMA用量的增加,纳米复合材料硫化胶的定伸应力、拉伸强度、扯断伸长率、撕裂强度和热氧老化性能逐渐提高.当MgMA含量为30份时,体系的拉伸强度和扯断伸长率分别为38.5MPa和545%,并具有优异的热空气老化性能.MgMA能明显增加HNBR复合材料的储能模量,并降低其损耗因子.随着MgMA用量的增加,纳米复合材料硫化胶的总交联密度(Ve)和离子键交联密度(Ve2)增加,而共价键交联密度(Ve1)下降,表明离子键对HNBR/PMgMA纳米复合材料的力学性能起重要作用.     

聚丙烯/凹凸棒石纳米复合材料的制备与性能研究

以聚丙烯(PP)为聚合物基体,天然凹凸棒石(ATP)为无机组分,经过氧化聚乙烯对ATP表面进行包覆处理,用熔融共混的方法制备了PP/ATP纳米复合材料.扫描电镜结果显示,经本方法处理后的ATP在PP基体中分散较为均匀.ATP棒晶簇直径最佳分散尺寸能达到20~40 nm,比未处理ATP在基体中的棒晶簇直径小10 nm以上;XRD测试表明,未处理ATP和处理后的ATP均有使PP晶粒细化的作用,同时不改变PP的α晶型;DSC结果显示,ATP的加入提高了PP的结晶温度和结晶度,说明ATP有一定的成核作用.通过对复合材料的力学性能测试发现,经过处理的ATP制备的复合材料力学性能优于未处理ATP复合材料对PP力学性能的改善.其中ATP与氧化聚乙烯固含量的质量比为2∶1,ATP含量为3 wt%时复合材料力学性能达到最好.缺口冲击强度比纯PP最高提高了83%,提高幅度显著;经过处理的ATP制备的复合材料拉伸强度提高了6%~11%;弯曲强度提高了33%~45%;弯曲模量提高了90%~106%.     

Isothermal crystallization kinetics of poly(butylene terephthalate)/attapulgite nanocomposites

Poly(butylene terephthalate) (PBT)/organo‐attapulgite (ATT) nanocomposites containing 2.5 and 5 wt % nanoparticles loadings were fabricated via a simple melt‐compounding approach. The crystal structure and isothermal crystallization behaviors of PBT composites were studied by wide‐angle X‐ray diffraction and differential scanning calorimetry, respectively. The X‐ray diffraction results indicated that the addition of ATT did not alter the crystal structure of PBT and the crystallites in all the samples were triclinic α‐crystals. During the isothermal crystallization, the PBT nanocomposites exhibited higher crystallization rates than the neat PBT and the varied Avrami exponents when compared with the neat PBT. At the same time, the regime II/III transition was also observed in all the samples on the basis of Hoffman‐Laurizten theory, but the transition temperature increased with increasing ATT loadings. The fold surface free energy (σ_e) of polymer chains in the nanocomposites was lower than that in the neat PBT. It should be reasonable to treat ATT as a good nucleating agent for the crystallization of PBT, which plays a determinant effect on the reduction in σ_e during the isothermal crystallization of the nanocomposites, even if the existence of ATT could restrict the segmental motion of PBT. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 2112–2121, 2006     

The role of interfacial chemistry and interactions in the dynamics of thermosetting polyurethane–multiwalled carbon nanotube composites at low filler contents

Acid-oxidized multiwalled carbon nanotubes (MWCNTs) were introduced into a polyurethane (PU) matrix at low filler levels (0.01–0.25 wt%) through either van der Waals or covalent interactions, and their glass transition dynamics using dynamic mechanical analysis and laser-interferometric creep rate spectroscopy was investigated. The nanocomposites reveal substantial impact on the PU glass transition dynamics, which depends on the nanotube content and type of interfacial interactions. The pronounced dynamic heterogeneity within the glass transition covering 200 °C range and the displacement of main PU relaxation maxima from around 0 to 80–140 °C were registered. The results are treated in the framework of chemical inhomogeneity, constrained dynamics effects, and different motional cooperativities. The peculiariaties of the glass transition dynamics in the composites are reflected in their dynamic and static mechanical properties, in particular a two- to threefold increase in modulus and tensile strength for the covalent interfacial interaction of MWCNTs with PU.