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1.
In this work, we prepared the interpenetrating polymer networks of bismaleimide and polyether-type polyurethane(polyoxypropylene)–crosslinked epoxy (BMI/PU(PPG)–EP IPNs) by employing the simultaneous bulk polymerization technique. The polyurethane (PU)–crosslinked epoxy was identified via infrared (IR) spectra analysis. Also investigated herein were the mechanical properties, including tensile strength, Izod impact strength, and fracture energy (GIC) of the IPNs with various BMI contents in PU–crosslinked epoxy matrix. In addition, differential scanning calorimetry (DSC) analysis and the thermogravimetric analysis (TGA) were performed to examine the thermal properties of the BMI/PU(PPG)–EP IPNs. In addition, morphology and dynamic mechanical analysis (DMA) of the BMI/PU(PPG)–EP IPNs were also studied. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 70: 2635–2645, 1998 相似文献
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Jinbo Li 《Polymer Bulletin》2006,56(4-5):377-384
Summary Epoxy resin/polyurethane interpenetrating polymer network nanocomposites with various contents of organophilic montmorillonite
(oM-EP/PU nanocomposites) were prepared by a sequential polymeric technique and an in situ intercalation method. X-ray diffraction(XRD), and transmission electronic microscopy(TEM) analysis showed that organophilic
montmorillonite (oMMT) disperses uniformly in epoxy resin/polyurethane interpenetrating networks(IPNs), and the intercalated
or exfoliated microstructures of oMMT are formed. Differential scanning calorimetry(DSC) test proved that oMMT promotes the
compatibility of EP phase and PU phase, and glass transition temperature(Tg) of oM-EP/PU nanocomposites improves with increasing oMMT content. Mechanical properties tests and thermal gravity analysis
(TGA) indicated that oMMT and the IPNs of EP and PU exhibit synergistic effect on improving mechanical and thermal properties
of pure EP. The mechanism of toughing and reinforcing of oM-EP/PU nanocomposites was further discussed by scanning electronic
microscope(SEM). 相似文献
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Interpenetrating polymer networks of bismaleimide‐modified polyurethane–epoxy systems were prepared using the aliphatic and aromatic bismaleimides‐ and polyurethane‐modified epoxy and cured in the presence of 4,4′‐diaminodiphenylmethane. Infrared spectral analysis was used to confirm the polyurethane‐crosslinked epoxy (PU–EP). The matrices developed were characterized by mechanical, thermal, electrical, and morphological studies. The results obtained from the mechanical studies indicate that the incorporation of polyurethane and bismaleimides into epoxy increased the tensile strength, flexural strength, and impact strength, according to their nature and percentage concentration. The results obtained from the thermal and electrical studies indicate that the incorporation of polyurethane into epoxy decreased the thermal properties (glass transition temperature, heat distortion temperature (HDT), thermal stability) and electrical properties (dielectric strength, volume and surface resistivity, and arc resistance). The incorporation of aromatic bismaleimide into the polyurethane‐modified epoxy system increased the glass transition temperature, thermal stability, and electrical properties. Decreased values of glass transition and HDT were obtained in the case of aliphatic bismaleimide‐modified polyurethane–epoxy system. Surface morphology of modified epoxy systems was studied using scanning electron microscopy, and it was found that the polyurethane‐modified epoxy systems exhibited heterogeneous morphology and bismaleimides‐modified epoxy systems showed a homogeneous morphology. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 99: 3592–3602, 2006 相似文献
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organoclay‐modified polyurethane/epoxy interpenetrating network nanocomposites (oM‐PU/EP nanocomposites) were prepared by adding organophilic montmorillonite (oMMT) to interpenetrating polymer networks (IPNs) of polyurethane and epoxy resin (PU/EP) which had been prepared by a sequential polymerization technique. Wide‐angle X‐ray diffraction (WAXD) and transmission electronic microscopy (TEM) analysis showed that the interpenetrating process of PU and EP improved the exfoliation and dispersion degree of oMMT. The effects of the NCO/OH ratio (isocyanate index), the weight ratio of PU/EP and oMMT content on the phase structure and the mechanical properties of the oM‐PU/EP nanocomposites were studied by tensile testing and scanning electronic microscopy (SEM). Water absorption tests showed that the PU/EP interpenetrating networks and oMMT had synergistic effects on improvement in the water resistance of the oM‐PU/EP nanocomposites. Differential scanning calorimetry (DSC) analysis showed that PU was compatible with EP and that the glass transition temperature (Tg) of the oM‐PU/EP nanocomposites increased with the oMMT content up to 3 wt%, and then decreased with further increasing oMMT content. The thermal stability of these nanocomposites with various oMMT contents was studied by thermogravimetric analysis (TGA), and the mechanism of thermal stability improvement was discussed according to the experimental results. Copyright © 2005 Society of Chemical Industry 相似文献
5.
为了研究聚氨酯(PU)对沥青的改性机理,以多亚甲基多苯基多异氰酸酯(PAPI)与聚己二酸乙二醇酯二元醇(PEA)、聚四氢呋喃(PTMEG)合成两种PU预聚体,并用其制备PU改性沥青。采用针入度、软化点、延度、黏度试验测试改性沥青基本性能,并通过傅里叶变换红外光谱(FTIR)、原子力显微镜(AFM)、热重(TG)分析、差示扫描量热法(DSC)对其微观结构及反应机理进行分析。研究结果表明,PAPI型PU可以通过物理和化学反应协同改善沥青的高低温性能,PU的加入可使沥青针入度降幅超过20%,软化点提升高于35%,延度性能提升超350%,两种PU改性剂均可显著提升沥青的黏度。PU与沥青反应生成PU-沥青枝接物提高了相容性,导致改性沥青的官能团比例发生变化,PU掺入后会增大沥青中蜂形结构的高度,从而提高沥青的高温性能。PAPI-PEA型PU改性沥青热稳定性优于PAPI-PTMEG型PU改性沥青,而PAPI-PTMEG型PU改性沥青具有更低的玻璃化转变温度。 相似文献
6.
Tribological mechanism improving the wear resistance of polyurethane/epoxy interpenetrating polymer network via nanodiamond hybridization
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Shaoling Xia Yingliang Liu Linqi Zhang Dongmei Wang Wenjun Zou Jin Peng Shaokui Cao 《应用聚合物科学杂志》2014,131(10)
The excellent synergistic effect of physical/mechanical properties of polyurethane/epoxy (PU/EP) interpenetrating polymer network (IPN) and the validity of nanofilling have one potential to improve the wear resistance of polymeric materials. With the aim of practical application, PU/EP IPN nanocomposites are prepared with nanodiamond (ND) as a reinforcing additive. Results showed the uniform thermal stability and the excellent compatibility between PU and EP in ND‐hybridized PU/EP IPN. Simultaneously, ND particles work as crosslinked points improving the physical/mechanical properties of ND‐hybridized PU/EP IPN, especially the wear resistance. The measurement of tribological property and the scanning electron microscope indicated that the wear resistance is able to be improved a lot by the formation of IPN and by the addition of ND. Consequently, the tribological mechanism of PU/EP IPN nanocomposites comes into being. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40244. 相似文献
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Novel castor oil‐based polyurethane/α‐zirconium phosphate (PU/α‐ZrP) composite films with different α‐ZrP loading (0–1.6 wt %) and different NCO/OH molar ratios were synthesized by a solution casting method. The characteristic properties of the PU/α‐ZrP composite films were examined by Fourier transform infrared spectroscopy (FTIR), thermal gravimetric analysis (TGA), differential scanning calorimetry (DSC), X‐ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and tensile testing. The results from Fourier transform infrared spectroscopy indicated that strong intermolecular hydrogen bonding formed between α‐ZrP and PU, XRD and SEM results revealed that the α‐ZrP particles were uniformly distributed in the PU matrix at low loading, and obvious aggregation existed at high loading. Because of hydrogen bonding interactions, the maximum values of tensile strength were obtained with 0.6 wt % α‐ZrP loading and 1.5 of NCO/OH molar ratio in the matrix. Evidence proved that the induced α‐ZrP used as a new filler material can affect considerably the mechanical and thermal properties of the composites. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011 相似文献
9.
This paper reports synthesis and characterization of polyurethane–urea (PU‐urea) and the nanocomposites derived from the PU‐urea with silicate clays. Organophilic montmorillonite cotreated by cetyl trimethyl ammonium bromide (CTAB) was synthesized and used to prepare PU‐urea/montmorillonite nanocomposites coatings. PU‐ureas were prepared from polyethylene glycol (PEG), polypropylene glycol (PPG), trimethylol propane (TMP), and 4,4′‐diphenylmethane diisocyanate (MDI) by reacting excess diisocyanate with polyether glycols. The excess isocyanate of the prepolymers was cured with atmospheric moisture. The synthesized moisture cured PU‐urea and nanocomposites were characterized by Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), differential scanning calorimetric (DSC), and angle resolved X‐ray photoelectron spectroscopy (AR‐XPS). The thermal stability of the PU‐urea nanocomposites was higher relative to the mother PU‐urea films. DSC results showed a slight enhancement in the soft segment glass transition temperature after 3 wt % clay loading. The surface properties showed an enrichment of the soft segment toward the surface. An enhancement in the hard segment composition in the nanocomposite coatings has resulted in enhancing the phase mixing process. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 2393–2401, 2006 相似文献
10.
Hydroxyl‐, amine‐, and anhydride‐terminated polyurethane (PU) prepolymers, which were synthesized from polyether [poly(tetramethylene glycol)] diol, 4,4′‐diphenylmethane diisocyanate, and a coupling agent, bisphenol‐A (Bis‐A), 4,4′‐diaminodiphenyl sulphone (DDS), or benzophenonetetracarboxylic dianhydride, were used to modify the toughness of Bis‐A diglycidyl ether epoxy resin cured with DDS. Besides the crystalline polymers, poly(butylene terephthalate) (PBT) and poly(hexamethylene adipamide) (nylon 6,6), with particle sizes under 40 μm were employed to further enhance the toughness of PU‐modified epoxy at a low particle content. As shown by the experimental results, the modified resin displayed a significant improvement in fracture energy and also its interfacial shear strength with polyaramid fiber. The hydroxyl‐terminated PU was the most effective among the three prepolymers. The toughening mechanism is discussed based on the morphological and the dynamic mechanical behavior of the modified epoxy resin. Fractography of the specimen observed by the scanning electron microscopy revealed that the modified resin had a two‐phase structure. The fracture properties of PBT‐particle‐filled epoxy were better than those of nylon 6,6‐particle‐filled epoxy. Nevertheless, the toughening effect of these crystalline polymer particles was much less efficient than that of PU modification. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 2903–2912, 2001 相似文献
11.
An organophilic palygorskite (o‐PGS) prepared by the treatment of natural palygorskite with hexadecyl trimethyl ammonium bromide was incorporated into interpenetrating polymer networks (IPNs) of polyurethane (PU) and epoxy resin (EP), and a series of PU/EP/clay nanocomposites were obtained by a sequential polymeric technique and compression‐molding method. X‐ray diffraction and scanning electron microscopy analysis showed that adding nanosize o‐PGS could promote the compatibility and phase structure of PU/EP IPN matrices. Tensile testing and thermal analysis proved that the mechanical and thermal properties of the PU/EP IPN nanocomposites were superior to those of the pure PU/EP IPN. This was attributed to the special fibrillar structure of palygorskite and the synergistic effect between o‐PGS and the IPN matrices. In addition, the swelling behavior studies indicated that the crosslink density of PU/EP IPN gradually increased with increasing o‐PGS content. The reason may be that o‐PGS made the chains more rigid and dense. As for the flame retardancy, the PU/EP nanocomposites had a higher limiting oxygen index than the pure PU. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009 相似文献
12.
The properties of inorganic nanoparticles/polymer composites depend on the dispersivity of nanoparticles in a polymer matrix. The effect of surface modification on the dispersivity of ZnO nanoparticles in a polyurethane (PU) resin matrix was investigated. The nanocomposites were characterized by scanning electron microscopy (SEM), thermogravimetric analysis, and X‐ray diffraction. The scanning electron micrographs show that ZnO nanoparticles (CDI–SA–APS–ZnO), which were modified by aminopropyltriethoxysilane (APS) and activated stearic acid (SA) by N,N′‐carbonyldiimidazole (CDI), can be homogeneously dispersed and had been encapsulated in the PU phase. The interfacial compatibility between ZnO nanoparticles and PU matrix was significantly improved by hydrophobically modifying ZnO nanoparticles with APS and SA. The tensile strength and elongation at break of PU/CDI–SA–APS–ZnO nanocomposites increased by 82 and 64% respectively, compared with the pure PU material. The thermal stability and ultraviolet‐shielding properties were also improved by incorporating ZnO nanoparticles into the PU matrix. POLYM. COMPOS., 35:237–244, 2014. © 2013 Society of Plastics Engineers 相似文献
13.
A liquid silicon/phosphorus containing flame retardant (DOPO–TVS) was synthesized with 9,10‐dihydro‐9‐oxa‐10‐phosphapheanthrene‐10‐oxid (DOPO) and triethoxyvinylsilane (TVS). Meanwhile, a modified epoxy resin (IPTS–EP) was prepared by grafting isocyanate propyl triethoxysilane (IPTS) to the side chain of bisphenol A epoxy resin (EP) through radical polymerization. Finally, the flame retardant (DOPO–TVS) was incorporated into the modified epoxy resin (IPTS–EP) through sol–gel reaction between the ethyoxyl of the two intermediates to obtain the silicon/phosphorus containing epoxy resin. The molecular structures of DOPO–TVS, IPTS–EP and the final modified epoxy resin were confirmed by FTIR spectra and 1H‐NMR, 31P‐NMR. Thermogravimetric analysis (TGA), differential scanning calorimetry, and limiting oxygen index were conducted to explore the thermal properties and flame retardancy of the synthesized epoxy resin. The thermal behavior and flame retardancy were improved. After heating to 600°C in a tube furnace, the char residue of the modified resin containing 10 wt % DOPO–TVS displayed more stable feature compared to that of pure EP, which was observed both by visual inspection and scanning electron microscope (SEM). Moreover, the mechanical performance testing results exhibited the modified epoxy resins possessed elevated tensile properties and fracture toughness which is supported by SEM observation of the tensile fracture section. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42788. 相似文献
14.
Layered double hydroxide (LDH) is a new type of nanofiller, which improves the physicochemical properties of the polymer matrix. In this study, 1, 3, 5, and 8 wt % of dodecyl sulfate‐intercalated LDH (DS‐LDH) has been used as nanofiller to prepare a series of thermoplastic polyurethane (PU) nanocomposites by solution intercalation method. PU/DS‐LDH composites so formed have been characterized by X‐ray diffraction and transmission electron microscopy analysis which show that the DS‐LDH layers are exfoliated at lower filler (1 and 3 wt %) loading followed by intercalation at higher filler (8 wt %) loading. Mechanical properties of the nanocomposite with 3 wt % of DS‐LDH content shows 67% improvement in tensile strength compared to pristine PU, which has been correlated in terms of fracture behavior of the nanocomposites using scanning electron microscope analysis. Thermogravimetric analysis shows that the thermal stability of the nanocomposite with 3 wt % DS‐LDH content is ≈ 29°C higher than neat PU. Limiting oxygen index of the nanocomposites is also improved from 19 to 23% in neat PU and PU/8 wt% DS‐LDH nanocomposites, respectively. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009 相似文献
15.
Lorenzo Bonetti Andrea Fiorati Andrea Serafini Guido Masotti Francesca Tana Agnese D'Agostino Lorenza Draghi Lina Altomare Roberto Chiesa Silvia Farè Massimiliano Bianchi Laura Giorgia Rizzi Luigi De Nardo 《应用聚合物科学杂志》2021,138(2):49645
The advent of 2D nanostructured materials as advanced fillers for polymer matrix composites has opened the doors to a plethora of new industrial applications requiring both electric and thermal management. Unique properties, in fact, can arise from accurate selection and processing of 2D fillers and their matrix. Here, we report an innovative family of nanocomposite membranes based on polyurethane (PU) and graphene nanoplatelets (GNPs), designed to improve thermal comfort in functional textiles. GNP particles were thoroughly characterized (through Raman, atomic force microscopy, high-resolution TEM, scanning electron microscope), and showed high crystallinity (ID/IG = 0.127), low thickness (D50 < 6–8 layers), and high lateral dimensions (D50 ≈ 3 μm). When GNPs were loaded (up to 10% wt/wt) into the PU matrix, their homogeneous dispersion resulted in an increase of the in-plane thermal conductivity of composite membranes up to 471%. The thermal dissipation of membranes, alone or coupled with cotton fabric, was further evaluated by means of an ad hoc system designed to simulate a human forearm. The results obtained provide a new strategy for the preparation of membranes suitable for technical textiles, with improved thermal comfort. 相似文献
16.
Hydroxyl-, amine-, and anhydride-terminated polyurethane (PU) prepolymer which were synthesized from polyether (PTMG) diol, 4,4′-diphenylmethane diisocyanate (MDI), and a coupling agent bisphenol-A, 4,4′-diaminodiphenyl sulfone (DDS), or benzophenonetetracarboxylic dianhydride (BTDA) were used to modify the toughness of bisphenol-A diglycidyl ether epoxy resin (DGEBA) cured with 4,4′-diaminodiphenyl sulfone. From the experimental results, it was shown that the modified resin displayed a significant improvement in fracture energy (GIC) and also in its interfacial shear strength with polyaramid fiber. It was more enhanced with increase of the PU modifier wt % content. The hydroxyl-terminated PU was found to be the most effective among those three prepolymers. In addition, the toughening mechanism was discussed based on the morphological and the dynamic mechanical behavior of the modified epoxy resin. Fractography of the specimen observed by transmission (TEM) and scanning electron microscopy (SEM) revealed that the modified resin had a two-phase structure. The existence of an unclean fiber surface after its fiber pullout test suggested that a ductile fracture might have occurred. © 1995 John Wiley & Sons, Inc. 相似文献
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Two series of toughened, semiconductive polyaniline (PANI)/polyurethane (PU)‐epoxy (PANI/PU‐EPOXY) nano‐composites were prepared using a conductive polymer, PANI, and PU prepolymer‐modified‐diglycidyl ether of bisphenol A (DGEBA) epoxy. First, the PU prepolymer‐modified epoxy oligomer was synthesized by a stoichiometric reaction between the terminal isocyanate groups of the PU prepolymer and the pendent hydroxyl groups of the epoxide. PU prepolymers were made either of polyester (polybutylene adipate, PBA) or polyether (polypropylene glycol, PPG) segments. The composites were characterized by thermal, morphological, mechanical, and electrical studies. Impact strength was enhanced 100% in PU (PPG 2000)‐modified composites; whereas, only ca. 30–50% increases in impact strength were observed for the other modified composites. In addition, the thermal stability of this composite proved superior to that of neat epoxy resin, regardless of a PU content at 27.5 wt%. Scanning electron microscopy (SEM) morphology study showed that the spherical PU (PPG 2000) particles (ca. 0.2–0.5 μm) dispersed within the matrix accounts for these extraordinary properties. The conductivity of the composite increased to ca. 10?9–10?3 S cm?1 upon addition of PANI when tested in the frequency range 1 kHz–13 MHz. This study demonstrated a useful way to simultaneously improve the toughness and conductivity of the epoxy composite, thus rendering it suitable for electromagnetic interference and various charge dissipation applications. POLYM. ENG. SCI., 2008. © 2007 Society of Plastics Engineers 相似文献
20.
Muhammad Fiayyaz Khalid Mahmood Zia Mohammad Zuber Tahir Jamil Muhammad Kaleem Khosa Muhammad Asghar Jamal 《Korean Journal of Chemical Engineering》2014,31(4):644-649
Polyurethanes (PUs) prepolymers blended with bentonite nanoclay and without bentonite nanoclay were prepared by the reaction of toluene-2,4-diisocyanate (TDI) and hydroxyl terminated polybutadiene (HTPB), and the chain was further extended with 1,4-butane diol (1,4-BDO) to get final polyurethane nanocomposites (PUNC). A mixture of polymer and bentonite clay enriched in montmorillonite (MMT) was formed in solution polymerization, in which MMT dispersed depending on interaction of MMT with polymer chains. The molecular structure of the monomers and the prepared PU nanocomposites was confirmed by FTIR. A series of PUNCs were prepared by varying the percent compositions of bentonite nanoclay into the PU matrix. The existence of the clay in to the PU was confirmed by scanning electron microscope (SEM). SEM images verified the good dispersion of the bentonite nanoclay in PU matrix. 相似文献