Retention of Mechanical and Thermal Properties of Hydrothermal Aged Glass Fiber-Reinforced Polymer Nanocomposites

The combined effect of nano-Al₂O₃ and TiO₂ fillers on residual mechanical and thermal properties of glass fiber-reinforced polymer composites has been evaluated. The results reveal that the addition of 0.1?wt% of Al₂O₃ and 0.1?wt% of TiO₂ into the epoxy matrix reduces the water diffusivity by 12%. The residual flexural and interlaminar shear strength of the nanocomposite have been increased by 19 and 21%, respectively, as compared to those of neat epoxy glass fiber-reinforced polymer composite. In spite of reduction in water diffusivity and increase in strength, there was no improvement in glass transition temperature of the nanocomposites.     

Effect of Tio2 Nanoparticles on the Antibacterial and Physical Properties of Low-Density Polyethylene Film

In this study, TiO₂ nanoparticles were incorporated into low-density polyethylene by melt blending. Morphological properties and dispersion behavior of TiO₂ nanocomposite were characterized through field emission scanning electron microscope, X-ray diffraction, and Fourier transform infrared spectroscopy. Thermal stability of the nanocomposites was determined by thermogravimetric analysis. Moreover, the mechanical properties of nanocomposites were determined. Antimicrobial activity of TiO₂ nanocomposites was investigated by in vitro test. Dispersion of the nanoparticles was good in nanocomposites_. According to thermogravimetric analysis, incorporation of TiO₂ nanoparticles into low-density polyethylene enhanced the thermal stability. Mechanical properties of nanocomposites were improved by TiO₂ nanoparticles. Results showed that the antibacterial effect of low-density polyethylene –TiO₂ nanocomposite was significantly enhanced by TiO₂nanoparticles (p?2 nanoparticles not only can improve the properties of low-density polyethylene but they also have the potential to be used as an active food packaging film.     

Hybridizing MWCNT with nano metal oxides and TiO2 in epoxy composites: Influence on mechanical and thermal performances

In this study, the effects of multi‐walled carbon nanotubes (MWCNT), and its hybrids with iron oxide (Fe₂O₃) and copper oxide (CuO) nanoparticles on mechanical characteristics and thermal properties of epoxy binder was evaluated. Furthermore, simultaneous effects of using MWCNT with TiO₂ as pigment and CaCO₃ as filler for epoxy composites were determined. To investigate effects of nano‐ and micro‐particles on epoxy matrix, the samples were evaluated by TGA and DTA. It was found that the hybrid of MWCNT with nano metal oxides caused considerable increment in the tensile and flexural properties of epoxy samples in comparison to the single MWCNT containing samples at the same filler contents. Significant improvement in the thermal conductivity of epoxy samples was obtained by using TiO₂ pigment along with MWCNT. The TiO₂ pigment also caused considerable improvement in mechanical properties of the epoxy matrix and the MWCNT containing nanocomposite. The best mechanical and thermal properties of epoxy nanocomposites were obtained at 1.5 wt % of MWCNT and 7 wt % of TiO₂ that it should be attributed to particle network forming of the particles which cause better nano/micro dispersion and properties. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43834.     

Preparation and properties of TiO2‐filled poly(acrylonitrile‐butadiene‐styrene)/epoxy hybrid composites

Poly (acrylonitrile‐butadiene‐styrene) (ABS) was used to modify diglycidyl ether of bisphenol‐A type of epoxy resin, and the modified epoxy resin was used as the matrix for making TiO₂ reinforced nanocomposites and were cured with diaminodiphenyl sulfone for superior mechanical and thermal properties. The hybrid nanocomposites were characterized by using thermogravimetric analyzer (TGA), dynamic mechanical analyzer (DMA), universal testing machine (UTM), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The bulk morphology was carefully analyzed by SEM and TEM and was supported by other techniques. DMA studies revealed that the DDS‐cured epoxy/ABS/TiO₂ hybrid composites systems have two T_gs corresponding to epoxy and ABS rich phases and have better load bearing capacity with the addition of TiO₂ particles. The addition of TiO₂ induces a significant increase in tensile properties, impact strength, and fracture toughness with respect to neat blend matrix. Tensile toughness reveals a twofold increase with the addition of 0.7 wt % TiO₂ filler in the blend matrix with respect to neat blend. SEM micrographs of fractured surfaces establish a synergetic effect of both ABS and TiO₂ components in the epoxy matrix. The phenomenon such us cavitation, crack path deflection, crack pinning, ductile tearing of the thermoplastic, and local plastic deformation of the matrix with some minor agglomerates of TiO₂ are observed. However, between these agglomerates, the particles are separated well and are distributed homogeneously within the polymer matrix. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Preparation and performance of high‐impact polystyrene (HIPS)/nano‐TiO2 nanocomposites

High‐impact polystyrene (HIPS)/nano‐TiO₂ nanocomposites were prepared by surface pretreatment of nano‐TiO₂ with special structure dispersing agent (TAS) and master batch manufacturing technology. The results show that when the nano‐TiO₂ content is 2%, the notched impact strength, tensile strength, and elastic modulus of HIPS/nano‐TiO₂ nanocomposites increased to a maximum. This result indicates that nano‐TiO₂ has both toughening and reinforcing effects on HIPS. The heat‐deflection temperature and flame‐retardance of HIPS/nano‐TiO₂ nanocomposites are also obviously improved as the nano‐TiO₂ content is increased. The nanocomposites manufactured by the two‐step method have better mechanical properties than that made by a one‐step method. HIPS/nano‐TiO₂ nanocomposites are also non‐Newtonian and pseudoplastic fluids. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 381–385, 2003     

The Effect of WS2 Nanotubes on the Properties of Epoxy-Based Nanocomposites

In this paper we evaluated the effect of embedding inorganic nanotubes (INT) of tungsten disulfide (WS₂) in an epoxy matrix, on the mechanical, thermal and adhesion properties of the resulting nanocomposites. The nanotube content spanned a range of values (0, 0.1, 0.3, 0.5 and 1.0 wt%), and the nanotube incorporation process consisted of a combination of both distributive (magnetic stirring) and dispersive (ultrasonic mixing) methods. The adhesion of the nanocomposites to an aluminum substrate was characterized by both a single lap shear and a T-peel test. The fracture toughness (K _IC) of the nanocomposites was characterized by a standard compact tension (CT) plane-strain fracture test. The thermal properties of the nanocomposites were determined by dynamic mechanical thermal analysis (DMTA). Overall, the addition of INT-WS₂ was found to improve the shear strength and peel properties of the nanocomposite, and to significantly improve its fracture toughness and glass transition temperature. The extent and character of the nanotube–epoxy interaction were examined by electron microscopy, as was the energy dissipation mechanisms during fracture.     

One-step synthesis of improved silica/epoxy nanocomposites with inorganic-organic hybrid network

High performance silica/epoxy nanocomposites were prepared through mixing epoxy, tetraethyl orthosilicate (TEOS), γ-aminoproplytriethyoxy siliane(APTES), and triethyltrtramine (TETA) at 25 °C via sol-gel method on one-step. The effects of content of TEOS and coupling reagents on the mechanical and thermal properties of SiO₂/EP composites were studied. Microcosmic morphology and properties of the hybrid materials were characterized by FT-IR, TEM, FESEM, and DSC. Results revealed that SiO₂/EP composites achieve the optimal mechanical and thermal properties when the composites prepared with mass ratio of TEOS/APTES/epoxy for 3/2/100 without acetone. Compared with pristine epoxy, the tensile strength, elongation at break, impact strength and bend strength increased 67.6 %, 190 %, 82.1 % and 15.7 %, respectively. The further study was to investigate the content of TEOS and APTES effecting on mechanical properties and water sorption of fiber reinforced composites, which used the above compound as matrix resin.     

Effects of particle type on thermal and mechanical properties of polyoxymethylene nanocomposites

The effects of particle size of titanium dioxide (TiO₂) on mechanical, thermal, and morphological properties of pure polyoxymethylene (POM) and POM/TiO₂ nanocomposites were investigated and compared with the results for nanoparticle ZnO in the same matrix, reported in a previous paper. POM/TiO₂ nanocomposites with varying concentration of TiO₂ were prepared by the melt mixing technique in a twin screw extruder, the same method that used for blending the homogeneous ZnO nanocomposites. The dispersion of TiO₂ particles in POM nanocomposites was studied by scanning electron microscopy (SEM). The agglomeration, as observed by the mechanical properties of TiO₂ particles in the polymer matrix, increased with increasing TiO₂ content, a result not found for ZnO even at lower particle sizes. Increasing the filler content of POM/TD32.4 and POM/TD130 (130 nm) nanocomposites resulted in a decrease in tensile strength. The Young modulus, stress at break and impact strength of TiO₂ nanocomposite did not improve with increasing filler contents, in opposition to the better agglomeration conditions of ZnO nanocomposite even at lower particle sizes. Because of agglomeration, the POM/TD32.4 nanocomposites had lower mechanical properties and lower degradation temperature than the POM/TD130 ones. The sizes of nanoparticles determined the agglomeration, but however, the agglomeration also depended on the type of nanoparticles, even when using the same matrix (POM) and the same mixing method. TiO₂ nanoparticles were more difficult to mix and were more agglomerated in the POM matrix as compared to ZnO nanoparticles, regardless of the size of the nanoparticles. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Thermo mechanical behaviour of unsaturated polyester toughened epoxy–clay hybrid nanocomposites

The intercrosslinked networks of unsaturated polyester (UP) toughened epoxy–clay hybrid nanocomposites have been developed. Epoxy resin (DGEBA) was toughened with 5, 10 and 15% (by wt) of unsaturated polyester using benzoyl peroxide as radical initiator and 4,4′-diaminodiphenylmethane as a curing agent at appropriate conditions. The chemical reaction of unsaturated polyester with the epoxy resin was carried out thermally in presence of benzoyl peroxide-radical initiator and the resulting product was analyzed by FT-IR spectra. Epoxy and unsaturated polyester toughened epoxy systems were further modified with 1, 3 and 5% (by wt) of organophilic montmorillonite (MMT) clay. Clay filled hybrid UP-epoxy matrices, developed in the form of castings were characterized for their thermal and mechanical properties. Thermal behaviour of the matrices was characterized by differential scanning calorimetry (DSC), thermo gravimetric analysis (TGA) and dynamic mechanical analysis (DMA). Mechanical properties were studied as per ASTM standards. Data resulted from mechanical and thermal studies indicated that the introduction of unsaturated polyester into epoxy resin improved the thermal stability and impact strength to an appreciable extent. The impact strength of 3% clay filled epoxy system was increased by 19.2% compared to that of unmodified epoxy resin system. However, the introduction of both UP and organophilic MMT clay into epoxy resin enhanced the values of mechanical properties and thermal stability according to their percentage content. The impact strength of 3% clay filled 10% UP toughened epoxy system was increased by 26.3% compared to that of unmodified epoxy system. The intercalated nanocomposites exhibited higher dynamic modulus (from 3,072 to 3,820 MPa) than unmodified epoxy resin. From the X-ray diffraction (XRD) analysis, it was observed that the presence of d ₀₀₁ reflections of the organophilic MMT clay in the cured product indicated the development of intercalated clay structure which in turn confirmed the formation of intercalated nanocomposites. The homogeneous morphologies of the UP toughened epoxy and UP toughened epoxy–clay hybrid systems were ascertained from scanning electron microscope (SEM).     

Influence of Submicron TiO2 Particles on the Mechanical Properties and Fracture Characteristics of Cured Epoxy Resin

Submicron titanium dioxide (TiO₂) was used in different weight fractions as a toughening agent for amine-cured epoxy resin. After the use of X-ray photoelectron spectroscopy (XPS), which confirmed that the TiO₂ particles were evenly distributed in the cross-linked epoxy resin matrix, the composites were characterized by tensile and impact testing, followed by scanning electron microscopy of the fracture surfaces. The results indicated that the submicron TiO₂ toughening particles markedly improved the mechanical properties of the cured epoxy resin compared to the untoughened epoxy resin. The optimal properties were achieved at a TiO₂ concentration of 4 wt. %, at which point the toughness and the impact resistance values increased by 65% and 60%, respectively. The results also indicated that an increase in the amount of TiO₂ causes a decrease in toughness. Stress whitening, out-of-plane flaking, and thumbnail markings were the major visible features of the toughening mechanisms.

It is suggested that, at 4 wt. % of the submicron TiO₂ particles, microvoids are developed in the epoxy matrix. These microvoids are able to absorb some of the deformation work applied to the material, and thus enhance the toughness of the material. On increasing the TiO₂ content in the matrix (> 4 wt. %), the submicron particles got closer to each other and the microvoids were converted to macrovoids, which may act as stress concentrating flaws, leading to the deterioration of the mechanical properties of the epoxy resin.     

Poly(lactic acid)/titanium dioxide nanocomposite films: Influence of processing procedure on dispersion of titanium dioxide and photocatalytic activity

Poly(lactic acid)/titanium dioxide (TiO₂) composite films were prepared by direct melt processing using three different procedures (i.e., compression molding, twin‐screw melt extrusion, and melt extrusion and thermoforming). The effect of TiO₂ loading and processing procedures on the phase morphology and on the thermal, mechanical, and barrier properties of the obtained nanocomposites were analyzed respectively by field‐emission scanning electron microscopy‐energy dispersive spectrometry, differential scanning calorimetry, universal testing machine, and water vapor and oxygen permeability measurements. The incorporation of TiO₂ nanoparticles into the poly(lactic acid) matrix increased the crystallinity and improved the barrier properties of the composites. The maximum tensile strength was achieved at the 2% content of TiO₂ for the films produced by compression molding and twin‐screw melt extrusion, whereas the tensile strength for films produced by melt extrusion and thermoforming decreases markedly with an increasing TiO₂ content. The photocatalytic activities of the obtained nanocomposites were investigated by analyzing the degradation of methyl orange. Results confirmed that the processing procedures and the distribution of TiO₂ in the polymer matrix are the key parameters, which rule the photocatalytic behavior of composite films. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers     

Preparation,characterization, and properties of TiO2/PLA nanocomposites by in situ polymerization

In situ polymerization method was used to prepare TiO₂/polylactide (PLA) nanocomposites with different contents of TiO₂ in this work. The size of the organically modified TiO₂ particles was investigated by X‐ray diffraction (XRD) analysis. Scanning electron microscope (SEM) shows that nano‐TiO₂ particles disperse in the PLA evenly when the content of TiO₂ is low (less than 3 wt%). The differential scanning calorimeter (DSC), thermogravimetry analysis (TGA), and tensile test were used to study the thermal and mechanical properties of the composites. Results show that both the thermal and mechanical properties are markedly improved when the content of TiO₂ is 3 wt%. UV light irradiation and solution degradation experiment show that degradation of the composites is higher when the content of TiO₂ increases and due to the introduction of TiO₂ particles in the nanocomposites, the TiO₂/PLA nanocomposites exhibit remarkable bacteriostasic activity. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers     

Reinforcing effect of amine-functionalized and carboxylated porous graphene on toughness,thermal stability,and electrical conductivity of epoxy-based nanocomposites

Epoxy-based nanocomposites reinforced with nonfunctionalized porous graphene (NPG), carboxylated porous graphene (CNPG), and amine-functionalized porous graphene (ANPG) were investigated with regard to mechanical properties, thermal stability, and electrical conductivity. Nanomaterials were added to the epoxy matrix in varying contents of 0.5, 1, and 2 wt %. Generally, mechanical properties were improved as a result of introducing nanomaterials into the epoxy resin. However, the amelioration of toughness was only observed in functionalized NPGs/epoxy nanocomposites. Field emission scanning electron microscopy images showed that functionalized nanomaterials induced a rougher fracture surface compared to the neat epoxy. Dynamic mechanical analysis along with differential scanning calorimetry confirmed an increment in the glass-transition temperature (T_g) of the reinforced nanocomposites. Also, they proved that functionalization made the epoxy network tougher and more flexible. The electrical conductivity and thermal stability of the epoxy resin were also improved when loaded with nanomaterials. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47475.     

Mechanical,thermomechanical, and creep performance of CNT embedded epoxy at elevated temperatures: An emphasis on the role of carboxyl functionalization

In contrast to polymeric composites, the role of interface/interphase has been widely acknowledged to govern their overall properties and performance. Environmental temperature has substantial effects on the interfacial durability of polymer nanocomposites. In this regard, present investigation has been carried out to study the mechanical performance of pristine (UCNT) and carboxylic functionalized CNT (FCNT) embedded epoxy nanocomposites under different elevated temperatures. Higher flexural strength and modulus of FCNT‐EP nanocomposite were recorded over UCNT‐EP and neat epoxy at room temperature environment. Flexural testing at elevated temperatures revealed a higher rate of strength degradation in polymer nanocomposites over neat epoxy. Postfailure analysis of specimens has been conducted to understand the alteration in failure micro‐mechanisms upon UCNTs and FCNTs addition in epoxy. Variation in viscoelastic properties with temperature has been studied from dynamic mechanical thermal analysis and significant reduction in glass transition temperature (T_g) is observed for nanocomposites. In the studied temperature and stress combinations, FCNT‐EP nanocomposites exhibited better creep resistance over UCNT‐EP and neat epoxy. Room temperature strengthening, elevated temperature strength degradations, improved creep resistance and reduction in T_g in nanocomposites over neat polymer have been discussed in terms of dynamic nature and gradient structure of CNT/epoxy interphase. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44851.     

Synthesis and characterization of bionanocomposites of poly(lactic acid) and TiO2 nanowires by in situ polymerization

Bionanocomposites from biopolymers and inorganic nanoparticles are of great interest for packaging materials due to their enhanced physical, thermal, mechanical, and processing characteristics. In this study, poly(lactic acid) (PLA) nanocomposites with covalent bonding between TiO₂ nanowire surface and PLA chains were synthesized through in situ melt polycondensation. Molecular weight, structure, morphology, and thermal properties were characterized. Fourier transform infrared spectroscopy confirmed that PLA chains were covalently grafted onto TiO₂ nanowire surface. Transmission electron microscopy images also revealed clearly a third phase presence on the nanowires after the grafting process. Those grafted PLA chains exhibited significantly increased glass transition temperature and thermal stability, compared with pure PLA. The weight-average molecular weight of PLA/2% TiO₂ nanowire bulk nanocomposites increased by 66% compared with that of pure PLA. The electron microscopy results showed that strong interfacial interaction and homogeneous distribution were achieved between inorganic nanowires and organic PLA matrix in the bulk nanocomposites. The PLA matrix in bulk nanocomposites exhibited elevated glass transition temperature and decreased crystallization ability as the TiO₂ nanowire concentrations were increased from 0 to 2%.     

Synthesis, thermal properties, and specific interactions of high Tg increase in poly(2,6-dimethyl-1,4-phenylene oxide)-block-polystyrene copolymers

We have synthesized a series of block copolymers of poly(2,6-dimethyl-1,4-phenylene oxide) and polystyrene (PPO-b-PS copolymer) by atom transfer radical polymerization. The PS content in these copolymer systems was determined by using infrared spectroscopy, thermal gravimetric analysis, and solution and solid-state NMR spectroscopy; good correlations exist between these characterization methods. DSC analyses indicated that the PPO-b-PS copolymers have higher glass transition temperatures than do their corresponding PPO/PS blends. Our FTIR and solid-state NMR spectroscopic analyses suggest that the PPO-b-PS copolymers possess stronger specific interactions that are responsible for the observed relatively higher values of T_g. We found one single dynamic relaxation from the dynamic mechanical analysis, which implies dynamic homogeneity exists in the PPO-b-PS copolymer; this result is consistent with the one single proton spin-lattice relaxation time observed in the rotating frame [T_1ρ(H)] during solid state NMR spectroscopic analysis. In addition, the 2D FTIR spectroscopy reveals evidence for the stronger interactions between segments of PPO and PS through the formation of π-cation complexes.     

Thermal and mechanical behavior of poly(vinyl butyral)‐modified novolac epoxy/multiwalled carbon nanotube nanocomposites

The effects of poly(vinyl butyral) (PVB) and acid‐functionalized multiwalled carbon nanotube modification on the thermal and mechanical properties of novolac epoxy nanocomposites were investigated. The nanocomposite containing 1.5 wt % PVB and 0.1 wt % functionalized carbon nanotubes showed an increment of about 15°C in the peak degradation temperature compared to the neat novolac epoxy. The glass‐transition temperature of the novolac epoxy decreased with increasing PVB content but increased with an increase in the functionalized carbon nanotube concentration. The nanocomposites showed a lower tensile strength compared to the neat novolac epoxy; however, the elongation at break improved gradually with increasing PVB content. Maximum elongation and impact strength values of 7.4% and 17.0 kJ/m² were achieved in the nanocomposite containing 1.5 wt % PVB and 0.25 wt % functionalized carbon nanotubes. The fractured surface morphology was examined with field emission scanning electron microscopy, and correlated with the mechanical properties. The functionalized carbon nanotubes showed preferential accumulation in the PVB phase beyond 0.25 wt % loading. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43333.     

Structural,thermal, and mechanical properties of silanized boron carbide doped epoxy nanocomposites

In the presented study, the structural, thermal, and mechanical properties of the nanocomposites were investigated by doping silanized hexagonal boron carbide (h-B₄C) nanoparticles in varying proportions (0.5%, 1%, 2%, 3%, 4%, and 5%) into the epoxy resin by weight. For this purpose, the surfaces of h-B₄C nanoparticles were silanized by using 3-(glycidyloxypropyl) trimethoxysilane (GPS) to improve adhesion between h-B₄C nanoparticles and epoxy matrix. Then, the silanized nanoparticles were added to the resin by ultrasonication and mechanical stirring techniques to produce nanocomposites. The bond structure differences of silanized B₄C nanoparticles (s-B₄C) and nanoparticle doped composites were investigated by using Fourier transform infrared spectroscopy. Scanning electron microscopy and energy dispersion X-ray spectroscopy (SEM-EDS) technique was used to examine the distribution of nanoparticles in the modified nanocomposites. Differential scanning calorimetry and thermogravimetric analysis techniques were used to determine the thermal properties of the neat and s-B₄C doped nanocomposites. The tensile test and dynamic mechanical analysis were performed to determine the mechanical properties. When the experimental results were examined, changes in the bonding structure of the s-B₄C nanoparticles doped nanocomposites and significant improvements in the mechanical and thermal properties were observed. The optimum doping ratio was determined as 2% by weight. At this doping ratio, the T_g, tensile strength and storage modulus increased approximately 18%, 35%, and 44% compared to the neat composite, respectively.     

Synthesis and dielectric properties of polyaniline/titanium dioxide nanocomposites

Two series of polyaniline–TiO₂ nanocomposite materials were prepared in base form by in situ polymerization of aniline with inorganic fillers using TiO₂ nanoparticles (P25) and TiO₂ colloids (Hombikat), respectively. The effect of particle sizes and contents of TiO₂ materials on their dielectric properties was evaluated. The as-synthesized polyaniline–TiO₂ nanocomposite materials were characterized by transmission electron microscopy (TEM), Fourier transform infrared (FTIR), thermal analysis (DTA/TGA), and X-ray diffraction (XRD). Dielectric properties of polyaniline–TiO₂ nanocomposites in the form of films were measured at 1 KHz–1 MHz and a temperature range of 35–150 °C. Higher dielectric constants and dielectric losses of polyaniline–TiO₂ nanocomposites than those of neat PANI were found. PANI–TiO₂ nanocomposites derived from P25 exhibited higher dielectric constants and losses than those from Hombikat TiO₂ colloids. Electrical conductivity measurements indicate that the conductivity of nanocomposites is increased with TiO₂ content. The dielectric properties and conductivities are considered to be enhanced due to the addition of TiO₂, which might induce the formation of a more efficient network for charge transport in the base polyaniline matrix.     

Effect of TiO2 addition on the microstructures,mechanical and dielectric properties of porous Si3N4-based ceramics

Porous Si₃N₄-based ceramics with different TiO₂ contents were prepared by gas pressure sintering method. The effects of TiO₂ addition ranging from 0 to 25?wt-% on the phase compositions, microstructures, mechanical performance and dielectric properties were investigated. The addition of TiO₂ significantly promoted the density which increased from 1.64 to about 2.3?g?cm^?3. The mechanical properties of porous Si₃N₄-based ceramics with TiO₂ addition decreased first and then increased with the increase of TiO₂ content, and the flexural strength and elastic modulus are more than 167.4?MPa and 72.8?GPa, respectively, which were higher than that of the Si₃N₄ ceramic without TiO₂ addition. With the increase of TiO₂ content, both the dielectric constant and dielectric loss increased, and the dielectric constant enhanced obviously. These results suggested that the TiO₂ was beneficial for the improvement of mechanical properties and dielectric constant of porous Si₃N₄-based ceramics.