Thermal and Morphological Properties of Octa(maleimido phenyl) Silsesquioxane (OMPS)-Reinforced Polybenzoxazine Hybrid Nanocomposites

We prepared an octa maleimido functionalized POSS, namely octa(maleimido phenyl) silsesquioxane (OMPS)-reinforced polybenzoxazine hybrid nanocomposites, by using four different types of benzoxazines (BZ-Cy-DDM, BZ-Cy-DDE, BZ-Cy-DDS, and BZ-Cy-Ani). They were synthesized from 1,1-bis(3-methyl-4-hydroxyphenyl) cyclohexane, paraformaldehyde, and aromatic amines (4,4′-diaminodiphenylmethane, 4,4′-diaminodiphenylether, 4,4′-diaminodiphenylsulphone, and aniline) by the Mannich reaction. We used 10 wt.% OMPS in all four polybenzoxazine matrices in order to compare the effect of OMPS on various benzoxazines. They were polymerized through thermal ring-opening polymerization at identical conditions. The thermal properties of the resulting OMPS-reinforced polybenzoxazine hybrid nanocomposites were studied using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The dispersion of OMPS in the polybenzoxazine and nanostructure of the composites were confirmed by X-ray diffraction analysis, transmission electron microscopy, and atomic force microscopy.     

高岭土对不饱和聚酯树脂的热稳定性、阻燃及力学性能的影响

不饱和聚酯树脂;高岭土;纳米复合材料;原位聚合;阻燃;成炭     

Ball milling: An effective technique for the preparation of exfoliated clay filled unsaturated polyester toughened epoxy nanocomposite

This paper investigates the possibility of improving the mechanical and thermal properties of epoxy and unsaturated polyester toughened epoxy resins through the dispersion of octadecyl ammonium ion-exchanged montmorillonite (organoclay) through exfoliated mechanism. The nanocomposites prepared are characterized for their structural change and studied for their crystallite size, mechanical, thermal and water absorption (hydrophilicity) properties. The mechanical data indicates significant improvement in the flexural and tensile properties over the neat epoxy and UP-epoxy matrix according to the percentage content of organoclay. The thermal behavior too shows noticeable enhancement in glass transition temperature T _g and high thermal stability. Hydrophilicity of all the composites decreases irrespective of the concentration of organoclay on the epoxy and UP-epoxy matrices. The homogeneous morphology of epoxy and UP toughened epoxy nanocomposite hybrid systems is ascertained using scanning electron microscope (SEM). X-ray results point out that the cetyl ammonium modified clay filled composites exhibited the exfoliated structure.     

Critical aspects related to processing of carbon nanotube/unsaturated thermoset polyester nanocomposites

Carbon nanotubes (CNTs) have outstanding mechanical, thermal and electrical properties. As a result, particular interest has been recently given in exploiting these properties by incorporating carbon nanotubes into some form of matrix. Although unsaturated polyesters with styrene have widespread use in the industrial applications, surprisingly there is no study in the literature about CNT/thermoset polyester nanocomposite systems. In the present paper, we underline some important issues and limitations during the processing of unsaturated polyester resins with different types of carbon nanotubes. In that manner, 3-roll mill and sonication techniques were comparatively evaluated to process nanocomposites made of CNTs with and without amine (NH₂) functional groups and polyesters. It was found that styrene evaporation from the polyester resin system was a critical issue for nanocomposite processing. Rheological behaviour of the suspensions containing CNTs and tensile strengths of their resulting nanocomposites were characterized. CNT/polyester suspensions exhibited a shear thinning behaviour, while polyester resin blends act as a Newtonian fluid. It was also found that nanotubes with amine functional groups have better tensile strength, as compared to those with untreated CNTs. Transmission electron microscopy (TEM) was also employed to reveal the degree of dispersion of CNTs in the matrix.     

Morphology and performance of unsaturated polyester nanocomposites modified with organoclay and thermoplastic polyurethane

<正>Unsaturated polyester(UPR)/thermoplastic polyurethane(TPU)/organoclay nanocomposites were prepared by melt compounding of thermoplastic polyurethane and unsaturated polyester prepolymer,and then mixing with the hybrids of styrene monomers and organoclay at ambient temperature.The crosslinking reaction eventually occurred through the unsaturated polyester prepolymer and styrene monomer.The morphology of the composites was investigated by scanning electron microscopy(SEM) and transmission electron microscopy(TEM).The results show that the impact strength of UPR/TPU/organoclay nanocomposites increases obviously;the cure shrinkage decreases markedly,the glass transition temperature is enhanced and an elastic response to the deformation is prominent at the temperature above 10℃.     

Morphology,thermal stability,and flammability of polymer matrix composites coated with hybrid nanopapers

In this study, a hybrid nanopaper consisting of carbon nanofiber (CNF) and polyhedral oligomeric silsequioxane (POSS) or cloisite Na⁺ clay, has been fabricated through the papermaking process. The hybrid nanopaper was then coated on the surface of glass fiber (GF) reinforced polymer matrix composites through resin transfer molding (RTM) process. The morphologies of the hybrid nanopaper and resulting nanocomposites were characterized with scanning electron microscopy (SEM). It can be seen that the nanopaper had a porous structure with highly entangled carbon nanofibers and the polyester resin completely penetrated the nanopaper throughout the thickness. The thermal decomposition behavior of the hybrid nanopapers and nanocomposites was studied with the real‐time thermogravimetric analysis/ flourier transform infrared spectrometry (TGA/FTIR). The test results indicate that the addition of pristine nanoclay increased the thermal stability of the nanopaper, whereas the POSS particles decreased the thermal stability of the nanopaper. The fire retardant performance of composite laminates coated with the hybrid nanopaper was evaluated with cone calorimeter tests using a radiated heat flux of 50 kW/m². The cone calorimeter test results indicate that the peak heat release rate (PHRR) decreased dramatically in composite laminates coated with the CNF‐clay nanopaper. However, the PHRRs of the CNF‐POSS nanopaper coated composite laminates increased. The formation of compact char materials was observed on the surface of the residues of the CNF‐clay nanopaper after cone calorimeter test. The flame retardant mechanisms of the hybrid nanopaper in the composite laminates are discussed. Copyright © 2009 John Wiley & Sons, Ltd.     

Adhesion of Sol-Gel-Derived Organic-Inorganic Hybrid Coatings on Polyester

Inorganic coatings, including metal-oxide coatings, provide polymer surfaces with excellent abrasion and wear resistance, and protection against environmental degradation. However, one drawback associated with the incorporation of such ceramic coatings to polymeric materials is the adhesion characteristic at the ceramic-polymer interface. In this paper, two strategies for adhesion enhancement of ceramic coatings on polymer substrates were proposed: (1) formation of chemical bonds through surface condensation reactions, and (2) development of interlocked ceramic and polymeric networks through diffusion of alkoxide precursors. The current research has focused on the adhesion of sol-gel-derived organic-inorganic hybrid coatings on polyester by forming chemical bonds between the polymer substrate and the hybrid coatings, as well as developing interlocked polymeric and inorganic networks at the interface. Contact angle, wettability tests, and chemicalanalysis were done to verify the effectiveness of the adhesion of organic-inorganic hybrid coatings on polyester substrates. In addition, dry and wet thermal cycling tests were done to analyze the adhesion behavior of the hybrid coatings on polyester, followed by microscopy examination. It was found that although both approaches resulted in excellent adhesion of hybrid coatings on polyester, adhesion with interlocked ceramic and polymeric networks was far better than that with chemical bonds in the presence of water at elevated temperatures.     

不饱和聚酯的改性

综述了不饱和聚酯树脂的合成、性能以及改性方向。介绍了不饱和树脂功能化、精细化、高性能化的研究 ,并着重介绍了有机 /无机纳米复合不饱和聚酯的制备和性能     

Octa(maleimido phenyl) silsesquioxane copolymers

Octa(maleimido phenyl) silsesquioxane (OMPS) was prepared from octa(aminophenyl) silsesquioxane (OAPS) and maleic anhydride. Initially, octaphenyl silsesquioxane was prepared, and it was nitrated to obtain octa(nitrophenyl) silsesquioxane; subsequently, reduction was carried out to obtain OAPS. These compounds were characterized with Fourier transform infrared, NMR, gel permeation chromatography, and wide‐angle X‐ray diffraction. Differential scanning calorimetry scans of OMPS showed an exotherm above 100 °C, and it was attributed to the curing. The peak maximum temperature depended on the heating rate. Both Ozawa's and Kissinger's methods were used to determine the activation energy for the curing reaction, which was approximately 29 kcal/mol. OMPS was copolymerized with various molar percentages of (1) N,N′‐p‐phenylenedimaleimide (PPMI) and (2) urethane methacrylate (UMA) by thermal and free‐radical polymerization, respectively. The copolymers were characterized with differential scanning calorimetry, dielectric analysis, thermogravimetric analysis, and wide‐angle X‐ray diffraction. In the PPMI and UMA copolymer series, the glass‐transition temperature increased with an increase in the OMPS concentration. The permittivity of the UMA copolymers decreased and tan δ increased with an increase in the OMPS concentration. In air and nitrogen atmospheres, the thermal stability of the PPMI and UMA copolymers increased with an increase in the OMPS concentration. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 2483–2494, 2005     

Surface energy properties of lignin particles studied by inverse gas chromatography and interfacial adhesion in polyester composites with electromagnetic transparency

We introduce a simple spray drying method for the scaleup production of spherical organic (lignin) particles with sizes between 0.85 and 1.57 µm. We assess the surface energy of the lignin particles by inverse gas chromatography to reveal their role in composites synthesized with unsaturated polyester. Such nanocomposites are shown to be transparent to electromagnetic irradiation (millimeter wave bands). The permittivity and tanδ of the composite material reached values 3.01 and 0.01 at 28 GHz with 10% lignin content. Vinyl groups were introduced on the surface of the particles to achieve enhanced interfacial adhesion, and resulted in a reduced relative permittivity (2.75). Together with wave interactions, the mechanical and thermal properties of the composites are put in perspective, opening new opportunities in the development of bio-based devices for 5G high-speed communication.

     

Thermal degradation behaviour and kinetic analysis of unsaturated polyester-based composites and IPNs by conventional and modulated thermogravimetric analysis

The thermal degradation behaviour of epoxy/unsaturated polyester based polymer interpenetrating networks (IPNs), and unsaturated polyester containing various flame-retardants have been investigated by TGA and Py/GC/MS. The kinetic parameters of various polymers were analysed by conventional and modulated thermogravimetric analysis (MTGA) methods. The activation energies of degradation were calculated by the Coats-Redfern and MTGA methods, respectively. The results of both conventional and MTGA analyses reveal that the decomposition of IPNs consists of two non-interfering decomposition processes for epoxy polymer and cured unsaturated polyester, respectively. For the flame-retardant containing unsaturated polyesters, ammonium polyphosphate (APP) played an important role in the second-step of the pyrolysis reaction of APP-containing samples. It is important to note that the possibilities of reaction order for these pyrolysis processes are significantly distinguishable by Coats-Redfern method. Furthermore, the activation energies for various samples calculated by MTGA method are on average larger than those calculated from the Coats-Redfern method. The results also reveal that when either the flame-retardant or the epoxy was added to the unsaturated polyester, the heat resistance of the unsaturated polyester was enhanced.     

Thermal and viscoelastic properties of polyurethane-imide/clay hybrid coatings

This paper reports the synthesis and characterization of polyurethane (PU)-imide/clay hybrid coatings based on two types of polyester (PE) polyols (PE-1 and PE-2). PE-1 was prepared from neopentyl glycol (NPG), adipic acid (AA) and isophathalic acid (IPA), whereas PE-2 contains NPG, AA, IPA and TMP (trimethylol propane) with the same hydroxyl value 280 as PE-1. Cetyl trimethyl ammonium bromide (CTAB) modified montmorillonite (K10) was used as the organoclay for the synthesis of the hybrid coatings. The organoclay particles (3 wt%) were well-dispersed into the PE matrix by ultrasonication method. Then the isocyanate terminated PU prepolymers were synthesized by the reaction of polyester polyols with hard segments such as 2,4-toluene diisocyanate (TDI) or isophorone diisocyanate (IPDI) in different NCO/OH ratios e.g., 1.6:1, 2:1 and 3:1, respectively. Finally the thermally stable imide rings were incorporated into the PU backbone by complete reaction of excess NCO content present in the PU prepolymer with pyromellitic dianhydride (PMDA). The thermogravimetric analysis (TGA) shows a higher thermal stability for the PU-imide hybrid coatings with respect to the corresponding PU-imide films. A higher NCO/OH ratio has resulted in higher thermal stability. The activation energies of degradation were calculated by the Broido and Coats-Redfern methods, respectively. The dynamic mechanical thermal analysis (DMTA) results show an enhancement in the glass transition temperature value (T_g) for the clay containing hybrid coatings. The surface analysis by angle resolved X-ray photoelectron spectroscopy (AR-XPS) showed an enrichment of the soft segment towards the surface, and an enhancement in the hard segment composition in the hybrid coatings, resulted in phase mixing.     

HPMA/OMMT和HPMA/CPMI/OMMT纳米复合材料的制备与表征

通过甲基丙烯酸羟丙酯(HPMA)单体与N-(4-羧基苯基)马来酰亚胺(CPMI)单体在有机蒙脱土(OMMT)中经原位插层自由基聚合反应制备了聚合物-无机纳米复合材料.OMMT由钠基蒙脱土通过十六烷基溴化铵插层处理制备.通过XRD和TEM对复合材料结构进行了表征,证实HPMA单体和HPMA/CPMI共单体在OMMT中原位插层共聚得到的复合材料均为剥离型纳米复合材料.OMMT含量为3 wt%的PolyHPMA/OMMT纳米复合材料起始分解温度为250℃,比相应的纯聚合物的热分解温度提高30℃.随着OMMT含量的增加,热分解温度进一步提高.但在测试温度范围内,PolyHPMA/OMMT纳米复合材料均没有出现明显的玻璃化转变温度.     

Study of the thermal degradation of flame-retardant polyester GFRP using TGA and TG-FTIR-GC/MS

Journal of Thermal Analysis and Calorimetry - The thermal degradation behaviors of commercial flame-retardant unsaturated polyester glass fiber-reinforced plastic (polyester GFRP) containing...     

Enhancement of tensile,electrical and thermal properties of epoxy nanocomposites through chemical hybridization of polypyrrole and graphene oxide

This paper presents the properties of epoxy nanocomposites, prepared using a synthesized hybrid Polypyrrole-Graphene Oxide (PPy-GO) filler, via in-situ chemical polymerization, at various filler loadings (i.e., 0.5–2 w. t %). The microstructures and properties of the PPy-GO hybrids and epoxy nanocomposites were studied via Fourier transform infrared (FTIR), X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), mechanical (Tensile Properties), electrical, Dynamic mechanical thermal analysis (DMTA) and thermogravimetric analyses (TGA). Morphological study demonstrated that varying the nanofiller nature (PPy-GOs, PPy or GO) lead to different states of dispersion. Mechanical, electrical and thermal analysis demonstrated that the hybrid concentration and its architecture (PPy:GO ratio) are interesting factors significantly affected the properties of the epoxy based nanocomposites. On the other hand, the mechanical performance of the cured nanocomposites outperformed the PPy-GO, with enhancements of 78% and 51% of Young's modulus and strength, respectively. Here it has been established that the embedding of PPy-GO hybrids into pristine epoxy endows optimum dispersion of PPy and GO as well as better interfacial adhesion between the fillers and matrix, which results in a significant improvement in load transfer effectiveness. Electrical conductivity measurements showed that conductivity of epoxy filled nanocomposites increased up 10⁻⁴ S/cm for Epoxy/PPy-GO nanocomposites. DMTA test indicated that incorporation of PPy-GO resulted in a significantly increase in Tg of the resultant nanocomposites, which is attributed to the highly exfoliation structure and the stronger interfacial interaction. The PPy-GO particles enhanced electrical, thermal and mechanical properties of nanocomposites, confirming the synergistic effect of PPy-GO as multifunctional filler.     

碲化镉/马来酰亚胺三嗪纳米杂化材料的制备及其光性能研究

利用低温水相法, 以巯基丙酸(MPA)作为稳定剂制备了碲化镉(CdTe)量子点, 通过马来酰亚胺三嗪(TMT)中的三嗪基团与CdTe量子点表面富含的羧基之间的氢键作用, 得到了分散性能优良的纳米杂化材料. 利用紫外-可见吸收光谱、荧光光谱以及透射电子显微镜等手段对产物的光物理性质和形貌进行了表征. 结果表明, 马来酰亚胺三嗪与CdTe量子点杂化后, CdTe量子点的荧光发射峰有明显的蓝移, 在CdTe量子点和马来酰亚胺三嗪之间存在着能量转移, 并且纳米杂化材料的分散性也有明显的改善.     

Fluorene‐based polyester nanocomposites via in situ interlayer polymerization

Fluorene‐based polyester nanocomposites were prepared by in situ polymerization of equivalent weights of 9,9′‐dihexylfluorene‐2,7‐dicarboxylic acid and 4,4′‐dihydroxy‐1,4‐diphenoxybutane (DPB‐OH) in the presence of octadecyl‐montmorillonite (C₁₈‐MMT) as an organoclay. We investigated the intercalation of the organoclay among the polymer chains, with the aim of improving the thermal properties of the polyester. It was found that the addition of only a small amount of organoclay was enough to improve the polyester's thermal properties. The maximum enhancement of the thermal properties of the fluorene‐based polyester nanocomposites was observed with the dispersion of 5 wt% organoclay. Copyright © 2008 John Wiley & Sons, Ltd.     

Dispersion of polymeric-coated–silica aerogel particles in unsaturated polyester composites: Effects on thermal-mechanical properties

The thermal-mechanical properties of unsaturated polyester (UP) composite were enhanced by the dispersion of silica aerogel (SA) with preserved pores. Low-cost SA was prepared from rice husk via the sol-gel process and ambient pressure drying. A new method was proposed to encapsulate the hydrophobic aerogel surface pores with hydrophilic polyvinyl alcohol (PVA) film using the fluidized-bed coating process. The dispersion of PVA-coated aerogel with preserved pores in the polyester matrix resulted in an increase of specific compressive strength (44.1?MPa?·?cm³?g^?1), thermal insulation (0.23?W?m^?1?K^?1), and thermal stability (T_onset?=?310°C), but decreased the glass transition temperature (T_g?=?260°C).     

Enhanced thermal properties and flame retardancy of unsaturated polyester‐based hybrid materials containing phosphorus and silicon

A phosphorus and silicon containing liquid monomer (9,10‐dihydro‐9‐oxa‐10‐phosphaphenanthrene 10‐oxide–vinyltrimethoxysilane (DOPO–VTS)) was synthesized by the reaction between DOPO and VTS. DOPO–VTS and methacryloxypropyltrimethoxylsilane were introduced into unsaturated polyester resin to prepare flame retardant UPR/SiO₂ (FR‐UPR/SiO₂) hybrid materials by sol–gel method and curing process. DOPO–VTS contributes excellent flame retardancy to UPR matrix, which was confirmed by the limiting oxygen index and microscale combustion calorimeter results. The thermogravimetric analysis (TGA) results indicate that the FR‐UPR/SiO₂ hybrid materials possess higher thermal stability and residual char yields than those of pure UPR at high temperature region. The thermal degradation of materials was investigated by TGA/infrared spectrometry (TG‐IR) and real‐time infrared spectrometry (RT‐IR), providing insight into the thermal degradation mechanism. Moreover, scanning electron microscopy (SEM) and X‐ray photoelectron spectroscopy (XPS) were used to explore the morphologies and chemical components of the residual char. Copyright © 2013 John Wiley & Sons, Ltd.     

Effects of chemical modifications and MMT nanoclay addition on transport phenomena of naturally woven coconut sheath/polyester nanocomposites

Studies on the behavior of molecular transport properties such as thermal conductivity, gas permeability, volume and surface resistivity have been carried out for the naturally woven coconut sheath (CS) fiber reinforced composites with the addition of nanoclay and chemical treatment of fiber. The compression molding technique was used to fabricate the coconut sheath/clay reinforced hybrid composites. The morphological studies such as X-ray diffractogram (XRD), transmission electron microscopy (TEM) and scanning electron microscopy (SEM) have been carried out for polyester nanocomposites and coconut sheath fiber. The decreased gas permeability, thermal conductivity and volume and surface resistivity have been observed with increasing the weight percentage of nanoclay in polyester matrix. In chemical modifications, the alkali and silane treated coconut sheath reinforced composites have shown great influence on the transport properties due to the increasing hydrophilic nature by the topographical changes at the fiber surface. Dielectric strength has also been reported in this paper for all types of composites. Infra-red (IR) spectra have also been taken to study the physical and chemical structural changes of treated coconut sheath.