Polymer Pyrolysis Research Articles

Towards quantitative microplastic analysis using pyrolysis-gas chromatography coupled with mass spectrometry

Microplastic pollution from everyday plastic items has increased tremendously worldwide. Pyrolysis gas chromatography coupled to mass spectrometry (Py-GC/MS) has been widely investigated for the qualitative and quantitative analysis of microplastics in environmental samples. However, there are several pitfalls to consider when developing an appropriate protocol for their analysis. This study aimed at the development of an in-house database of primary (single) polymers, binary (two) polymers and tertiary (three) polymer mixtures. In this context the potential occurrence of gas phase reactions during pyrolysis of binary and tertiary polymers were investigated. Further, different diluters were tested for the accurate preparation of calibration standards for quantification purposes.Seven different polymers were included in this study, which were chosen due to their prevalence in daily plastic appliances. For each single polymer specific peaks could be identified and recommendation for quantifier analytes given. The analysis of binary polymer mixtures revealed gas phase reactions for PET with PVC, PVC with MDI-PU and PE with PVC. For these binary polymers, several different novel pyrolysis products, specific for the according binary polymer mixture, could be identified. These results confirmed that especially PVC exhibits strong interactions during co-pyrolysis with ester- and ether-based polymers. Similar results were obtained for tertiary polymers.For accurate preparation of calibration standards different diluters (silica, deactivated silica, calcium carbonate, THF and HFIP) were tested. It was observed that deactivated silica had only an influence on the pyrolysis of PET. Whereas, dilution with silica affected PA-6/66, PE, PET and MDI-PU. Only PVC was not influenced by dilution with silica.In conclusion, our results highlight the necessity of an international standard of reference material as well as a standardized analytical protocol for the analysis and quantification of polymers in environmental samples. It is crucial to use diluters suitable for the specific polymer, to exclude potential interactions of diluters with the polymer. The present work has to be seen as a foundation, but future work is needed to adequately address the quantification of polymers in environmental samples.

Damage behavior and toughening mechanism of SiCf/SiC-Ti3SiC2 composites: A combination of digital image correlation and acoustic emission

Matrix modification is an effective method to improve the mechanical properties of ceramic matrix composites, while the elucidation of corresponding damage mechanism is essential for the design and engineering application of composites. In this work, Ti3SiC2 particles were introduced into SiC matrix to fabricate Ti3SiC2 modified SiCf/SiC (SiCf/SiC-Ti3SiC2) composites by a hybrid technique of slurry suspension impregnation combined with polymer infiltration and pyrolysis. Compared with SiCf/SiC composites, the flexural strength and modulus of SiCf/SiC-Ti3SiC2 composites were increased by 17.8 % and 61.0 %, respectively. The three-point flexural damage behavior and failure mechanism of composites were systematically investigated and compared by the combination of digital image correlation and acoustic emission techniques. Based on the collaborative analysis of in-situ damage process, matrix micro-zone toughness and fracture morphology, the modification effect and toughening mechanism of Ti3SiC2 were revealed. The improved mechanical properties of SiCf/SiC-Ti3SiC2 composite could be ascribed to the more sufficient matrix cracking before composite failure and the increased matrix fracture energy by microcrack deflection. After matrix modification, the failure mechanism was dominated by the gradual propagation and growth of microcracks until the critical crack size, instead of the fast and unstable propagation of main crack.

N-doped Porous Carbon Derived from the Pyrolysis of a Polydopamine-coated Hypercross-linked Polymer for Enhanced CO2 Adsorption.

Porous carbon materials can simultaneously capture and convert carbon dioxide, helping to reduce greenhouse gas emissions and using carbon dioxide as a feedstock for the production of valuable chemicals or fuel. In this work, a series of N-doped porous carbons (PDA@HCP(x:y)-T) was prepared; the CO2 adsorption capacity of the prepared PDA@HCP(x:y)-T was enhanced by coating polydopamine (PDA) on a hypercross-linked polymer (HCP) and then adjusting the mass ratio of PDA to HCP and the carbonization temperature. The results showed that the prepared PDA@HCP(1:1)-850 exhibited a high CO2 adsorption capacity due to abundant micropores (0.6762 cm3/g), a high specific surface area (1220.8 m²/g), and moderate surface nitrogen content (2.75%). Notably, PDA@HCP(1:1)-850 exhibited the highest CO2 uptake of 6.46 mmol/g at 0 °C and 101 kPa. Critically, these N-doped porous carbons can also be used as catalysts for the reaction of CO2 with epichlorohydrin to form chloropropylene carbonate, with chloropropylene carbonate yielding up to 64% and selectivity of the reaction reaching 94%. As a result, these N-doped porous carbons could serve as potential candidates for CO2 capture and conversion due to their high reactivity, excellent CO2 uptake, and good catalytic performance.

Ultrahigh room and high − temperature mechanical properties of SiCf/SiC composites prepared by hybrid CVI and PIP methods: Effects of PIP temperature

Unidirectional (UD) SiCf/SiC composites were prepared using chemical vapor infiltration (CVI)-polymer infiltration and pyrolysis (PIP) hybrid procedure at different PIP temperatures of 1100 °C (1100PIP), 1300 °C (1300PIP), and 1500 °C (1500PIP). The effect of PIP temperature on the microstructure of each component was studied. Results showed that SiC fiber strength and interfacial shear strength (IFSS) were the main factors affecting the mechanical properties of the composite. At 1100 °C, the fiber was thermally stable and IFSS was high, due to which 1100PIP achieved ultrahigh mechanical performance with tensile strength of 901.0 ± 87.7 MPa, flexural strength of 2186.5 ± 192.5 MPa, and toughness of 80.6 ± 12.0 MPa·m1/2. At 1300 °C, IFSS decreased slightly, due to the crystallization of BN interphase. Hence, the mechanical performance of 1300PIP decreased slightly to 789.8 ± 42.9 MPa, 1935.9 ± 163.2 MPa, and 58.2 ± 4.0 MPa·m1/2, respectively. At 1500 °C, severe fiber ceramization and decrease in IFSS caused severe decline in mechanical performance to about half of that of 1100PIP. The crack could be deflected not only at the fiber/BN (F/B) interface, but also at the CVI SiC/PIP SiC (C/P) interface, due to the existence of free carbon layers at the C/P interface, which played an important role in improving the strength and toughness of the composite. 1300PIP also showed excellent strength at high − temperature. At 1350 °C and 1500 °C, its flexural strengths were as high as 1529.0 ± 73.0 MPa and 1223.1 ± 81.1 MPa, respectively. The thermal conductivity and thermal expansion coefficient were also tested. Their values were mainly affected by the grain size and thermal stabilities of the SiC fiber and PIP matrix.

Periodate activation with polyaniline-derived carbon for bisphenol A degradation: Insight into the roles of nitrogen dopants and non-radical species formation

Periodate-based advanced oxidation processes (PI-AOPs) activated by carbon catalysts have shown promising application prospects in the removal of emerging contaminants. Herein, a series of N-doped carbon catalysts (NC) were prepared by in-situ pyrolysis of N-containing polymers (polyaniline) to unveil the potential mechanism of N dopants on PI activation. The optimized sample NC700 showed a satisfying degradation performance, achieving 100 % removal of bisphenol A (BPA) at a concentration of 10 mg/L within 90 min in the presence of 0.1 mM PI. The impacts of various N types on PI activation were systematically investigated by dynamic fitting and density functional theory computations. These analyses highlighted the crucial role of graphitic N configuration on carbon surface, which exhibited the highest adsorption energy and a positive correlation with the normalized degradation efficiency. The chemical quenching experiments and electrochemical experiments confirmed that the BPA oxidation mechanism was primarily mediated electron transfer by [NC-PI]* complex, with singlet oxygen (1O2) /superoxide radicals (O2•–) playing a supplementary role. In situ ATR-SERAS measurement strengthened the understanding of PI activation by carbon catalyst based on electron transfer pathway. Owing to the non-radical oxidation mechanism, the NC/PI system had a broad pH adaptability and great anti-interference ability against typical wastewater components. This study provides mechanistic insights into the carbon-driven PI activation process for wastewater treatment, advancing the practical application of PI-AOPs.

Atomically dispersed Zn sites on N-doped carbon boosted transesterification of symmetrical organic carbonates with biomass-derived alcohols

Transesterification of symmetrical organic carbonates with alcohols to access the unsymmetrical ones is a highly attractive strategy for upgrading biomass-derived alcohols. Robust, facile-prepared, and cost-effective catalytic materials remain highly desirable for this route. Herein, we designed several Zn-based catalysts (denoted as Zn@C-T, where T represented the pyrolysis temperature) by the pyrolysis of Zn-based coordination polymer at different temperatures. Very interestingly, the prepared Zn@C-900 could efficiently catalyze the transesterification of diethyl carbonate (DEC) with various biomass-derived alcohols to synthesize the corresponding unsymmetrical organic carbonates with high yields (>95 %), resulting from the atomically dispersed ZnNx sites on the N-doped carbon. Notably, good catalytic activity could be obtained at a low temperature of 80 °C, representing the major breakthrough. Detailed investigations indicated that the excellent performance of Zn@C-900 originated mainly from the synergistic effect of Zn (to activate DEC) and N (to activate the alcohols) in the ZnNx sites. This work provided a promising efficient catalyst for low-temperature production of unsymmetrical organic carbonates via transesterification of DEC.

Effect of Graphite Nanoadditives on the Behavior of a Diesel Engine Fueled with Pyrolysis Fuel Recovered from Used Plastics.

Plastic waste accumulation is a significant threat to the environment and humans. Pyrolysis is a promising method for recycling plastic waste since all of the yields are useful, reducing the associated environmental risks of plastic waste. Energy recovery from used plastic waste can help restore ecosystems by utilizing waste as fuel while addressing the environmental problem of plastic disposal. This study experimentally investigates the application of oil obtained by the pyrolysis of waste high-density polyethylene (HDPE) as a viable energy source for diesel engines, offering a unique solution to the issues of plastic waste and energy sustainability. The catalytic pyrolysis method was employed to convert used HDPE plastics into a fuel called used polymer pyrolysis oil (UPO). The UPO was blended at 20% and 40% on a volume basis with mineral diesel. The graphite nanoadditives of 50 and 100 ppm were doped to enhance the properties of the UPO20 blend. The results showed that UPO20n100 blends exhibited a 2.79% increase in brake thermal efficiency and an 11.6% reduction in specific fuel consumption compared to diesel. Utilizing the UPO20n100 blend as a diesel engine fuel resulted in reductions of hydrocarbon, carbon monoxide, and smoke emissions by 8.9%, 9.9%, and 8.9%, respectively, compared with diesel operation. These findings provide a pathway for reducing plastic pollution and reliance on fossil fuels, with significant implications for the development of sustainable energy solutions. Additionally, this study presents a novel application of graphite nanoadditives in fuel blends prepared from used plastics, highlighting their significant impact on enhancing engine efficiency and reducing emissions.

Evolution of high temperature oxidation properties of SiCf/SiCN composites with BN interphase

In this study, SiC/SiCN composites with BN interphase were prepared using chemical vapor infiltration (CVI) and polymer infiltration and pyrolysis (PIP) methods. The evolution and related mechanisms of mechanical and microwave absorption properties of the composites after oxidation at 800 °C, 1000 °C, 1200 °C, and 1400 °C were investigated. The results showed that with the elevating of oxidation temperature, the flexural strength of SiC/SiCN composites gradually decreased, with a retention rate of 56.7 % after oxidation at 1400 °C. The main reasons for the deterioration of mechanical properties were the changes in the crystal structure of SiC fibers under high-temperature conditions and the formation of brittle SiO2 phases on the surface and interior of the SiCN matrix. With the increase in oxidation temperature, the microwave absorption performance of the composites showed an enhancing trend. The main reasons were that after oxidation treatment, the reduction of free carbon content and the formation of SiO2 film layers from the oxidation of SiC and SiCN led to a decrease in the complex permittivity of the composites, resulting in better impedance matching and dielectric loss capabilities. The contributions of BN interphase to stress dispersion, interface polarization, and oxidation protection significantly enhance the mechanical and electromagnetic absorption properties of the composites. Therefore, SiC/SiCN composites are high-temperature structural microwave absorbing materials with great application prospects.

C60 Fullerene-Reinforced Silicon Oxycarbide Composite Fiber Mats: Performance as Li-Ion Battery Electrodes.

Precursor-derived silicon oxycarbide (SiOC) has emerged as a potential high-capacity anode material for rechargeable Li-ion batteries. The polymer processing and pyrolysis route, a hallmark of polymer-derived ceramics, allows chemical interfacing with a variety of nanoprecursors and nanofiller phases to produce composites with low-dimensional structures such as fibers and coatings not readily attained in traditional sintered ceramics. Here, buckminsterfullerene or C60 was introduced as a filler phase in a hybrid precursor of 1,3,5,7-tetramethyl-1,3,5,7-tetravinyl-cyclotetrasiloxane (TTCS) along with polyvinylpyrrolidone or PVP as a spinning agent to fabricate electrospun fiber mats, which upon a high-heat treatment transformed to a C60-reinforced SiOC ceramic composite. Tested as the self-supporting working electrode in a Li-ion half-cell, C60-reinforced fiber mats show a much-improved reversible capacity (825 mA h g-1), nearly 100% Coulombic efficiency, and superior rate capability with low-capacity decay at high currents (only 25.5% decay at 800 mA g-1) compared to neat C60 and neat carbonized fiber electrodes.

Carbon-Interconnected Sodium Vanadium Phosphate Microparticles: Material Characterizations and Na+-Storage Performances

Sodium vanadium phosphate (Na3V2(PO4)3) with continuous carbon-coating (NVP/C) has been regarded as one of the most promising cathode materials for sodium-ion batteries (SIBs) owing to the three-dimensional sodium superionic conductor (NASICON) structure for fast sodium-ion migrations, high theoretical energy density (ca. 400 Wh/kg), and good thermal stability (450°C). In this study, carbon-interconnected NVP/C microparticles (C@NVP/C MPs) were successfully synthesized by employing ascorbic acid and sodium-containing polymer as dual carbon sources, followed by calcination at 750°C in an argon atmosphere. The resulting C@NVP/C MPs not only exhibited great crystallinity, high purity, and size of 5-10 μm but also possessed carbon amounts of 9.9 wt. %, as confirmed through the X-ray diffractometer, scanning electron microscope, and thermogravimetric analyzer, respectively. The cyclic voltammogram revealed that the potential difference between oxidation and reduction peaks of C@NVP/C (174 mV at 0.1 mV/sec and 382 mV at 1.0 mV/sec) was less than that of the NVP/C nanoparticles (197 mV at 0.1 mV/sec and 391 mV at 1.0 mV/sec) that were synthesized without adding the sodium-containing polymer. Moreover, the same reversible capacity was delivered from C@NVP/C, i.e., 75 mAh/g at 0.1 C. Those improved electrochemical performances could be attributed to the well-interconnection between NVP/C and carbon originating from the pyrolysis of sodium-containing polymer, creating additional electronic transportation pathways. Accordingly, the C@NVP/C MPs synthesized in the present study are reasonably anticipated to be promising cathode materials for SIBs.

Molecular Simulation Insights into Chemical-Grafted EPDM for Improving Charge Traps, Moisture Resistance, and Pyrolysis Tolerance

This study explores and verifies the chemical modifications achieved by grafting 4-formylcyclohexyl heptanoate (FH) and 4-(2,5-dioxopyrrolidin-1-yl) cyclohexane-1-carbaldehyde (CC) onto ethylene propylene diene monomer (EPDM) elastomer, a prevalent dielectric material used for reinforced insulation in cable accessories. Employing a rigorous theoretical methodology combining first-principles calculations, molecular dynamics, and Monte Carlo molecular simulations, we elucidate the intricate effects of these chemical-graft modifications on the polymeric structure of EPDM to resist charge transport, moisture-aging, and thermal impact of partial discharge. Our investigation uncovers the emergence of both shallow and deep charge traps within the material, effectively mitigating electron avalanche breakdown. Additionally, we scrutinize the influence of two proposed organic species, acting as grafting agents, on several crucial properties of EPDM including water adsorption uptake, heat capacity, molecular thermal vibration, and polymer pyrolysis. These modifications substantially bolster EPDM’s resistance to high-temperature electrical breakdown and water thermodynamic adsorption, while also enhancing its thermal stability, rendering the proposed chemical-graft modifications an effective way and underling mechanisms for ameliorating electrical insulation performances of EPDM elastomer. Our findings highlight the significant potential of graft modification in molecular structures through comprehensive molecular simulations, offering valuable insights for advancing competent elastomeric polymers in cable accessory insulation.

Micro/nanostructure constructed by in situ growth of SiC nanowires in porous Si3N4 ceramics

AbstractImplant materials with micro/nanostructures bear a closer resemblance with the features of natural bone, which influences the wettability, bone differentiation, and vascularization of materials. However, it is still technically challenging to design the inner wall and surface micro/nanostructures on macroporous bioceramics due to their brittleness. In this work, micro/nanostructured composites with Si3N4 whiskers as a framework, and the (inner) surface covered with SiC nanowires were prepared, denoted as SiC‐nw@Si3N4‐w bioceramics. The synthesis, adopting the green chemistry concept, was utilized from environmental products (carbon evaporated in the furnace at high temperature) and reaction impurities (carbon obtained by polymer pyrolysis and silicon obtained by Si3N4 decomposition) to synthesize SiC nanowires via a vapor‐solid growth mechanism. The prepared SiC‐nw@Si3N4‐w bioceramics have potential applications in bone repair due to their cell adhesion and proliferation.

In situ TEM Pyrolysis of Conductive 2D Coordination Polymers for Improved Application as Solid Acid Fuel Cell Electrode Materials

In situ TEM Pyrolysis of Conductive 2D Coordination Polymers for Improved Application as Solid Acid Fuel Cell Electrode Materials

Kinetics study of catalytic pyrolysis of polystyrene polymer using response surface method

Kinetics study of catalytic pyrolysis of polystyrene polymer using response surface method

Low-temperature sintering of SiC ceramics using a mixture of preceramic precursor and metal nanoparticles

Polymer infiltration and pyrolysis (PIP) has a limitation in increasing the relative density of SiC ceramics above 90 %. This is due to the blockage of open pore channels. In this study, a new process that incorporates Ni and graphite nanoparticles into SiC preceramic precursor is examined. Ni nanoparticles react with the SiC precursor to form low melting point nickel silicide phases which infiltrate into pores of the bulk without a blockage problem. In later infiltration cycles, graphite nanoparticles are added to convert the nickel silicide to nickel carbide and silicon carbide, which may prevent the deterioration of mechanical strength at high temperature. The relative density of SiC ceramics in this study increases to 92 % and above, which is higher than that of SiC ceramics prepared by the traditional PIP. The results of this study show a pathway to process high density SiC ceramics at relatively low sintering temperatures.

Processing and properties of 3D woven SiC/SiC composites with hybrid matrix

3D woven SiC/SiC composites with Sylramic™-iBN SiC fibers have been fabricated by first partially infiltrating 3D woven fiber preforms with SiC by chemical vapor infiltration (CVI) and then by polymer infiltration and pyrolysis (PIP) of SiC-yielding polymer. The influence of fiber architecture on damage evolution and failure mechanisms during tensile loading, in-plane tensile properties, transverse thermal conductivity, and interlaminar tensile strength of the composites has been investigated. Wherever possible, the data are compared with those of 2D woven melt infiltrated (MI), CVI, and (CVI+PIP) hybrid SiC/SiC composites. The composites exhibit 300-hr creep durability at 1482 °C in air at stresses up to 138 MPa and show potential for elevated-temperature applications. Further improvements in composite properties are possible by optimizing composite constituents and fiber architecture.

Low Volume Gas-Flow Seeding For Highly Resolved Velocimetry Of The Boundary Layer

Ensuring fire safety in polymeric materials, which are inherently flammable but widely used in various industries, is of significant societal and economic importance. This study is part of a broader effort to understand polymer combustion and flame retardant effectiveness at a fundamental level. A major focus is the behavior of polymers burning along a vertical wall, a configuration chosen to study the release of flammable gases during pyrolysis, which contributes to the self-sustaining combustion reaction of a fire. This process occurs predominantly near the polymer surface within the boundary layer, requiring detailed analysis to evaluate flame retardant effectiveness. Our experimental setup replicates polymer pyrolysis using a flame-wall interaction burner with a vertical jet and a small inlet to mimic the release of flammable gases. The primary challenge in this setup is the introduction of seeding particles for Particle Image Velocimetry (PIV) measurements at low volume flow rates, which is complicated by reflections from the wall and the small flow scale relative to the main flow. To address this problem, we have developed a novel piezo-based ultrasonic seeder capable of controlled seeding at extremely low flow rates, thereby improving the accuracy of PIV measurements in non-reactive configurations. This seeder uses a piezo ring to excite a perforated metal membrane, forming uniform aerosol droplets. The design ensures a steady supply of particles, which is critical for evaluating boundary layer conditions. Our results demonstrate the seeder’s ability to maintain sufficient seeding density in the low volume flow region, facilitating detailed velocimetry analysis. The innovative seeder design proves effective in overcoming the limitations of conventional methods and provides new insights into polymer combustion processes and the role of flame retardants.

Microwave-Assisted Pyrolysis of Carbon Fiber-Reinforced Polymers and Optimization Using the Box-Behnken Response Surface Methodology Tool.

This article introduces an eco-friendly method for the reclamation of carbon fiber-reinforced polymers (CFRP). The research project involved numerous experiments using microwave-assisted pyrolysis (MAP) to explore a range of factors, such as the inert gas flow, the power level, the On/Off frequency of rotation, and the reaction duration. To design the experiments, the three-level Box-Behnken optimization tool was employed. To determine the individual and combined effects of the input parameters on the thermal decomposition of the resin, the data were analyzed using least-squares variance adjustment. The results demonstrate that the models developed in this study were successful in predicting the direct parameters of influence in the microwave-assisted decomposition of CFRPs. An optimal set of operating conditions was found to be the maximum nitrogen flow (2.9 L/min) and the maximum operating experimental power (914 W). In addition, it was observed that the reactor vessel's On/Off rotation frequency and that increasing the reaction time beyond 6 min had no significant influence on the resin elimination percentage when compared to the two other parameters, i.e., power and carrier gas flow rate. Consequently, the above-mentioned conditions resulted in a maximum resin elimination percentage of 79.6%. Following successful MAP, various post-pyrolysis treatments were employed. These included mechanical abrasion using quartz sand, chemical dissolution, thermal oxidative treatment using a microwave (MW) applicator and thermal oxidative treatment in a conventional furnace. Among these post-treatment techniques, thermal oxidation and chemical dissolution were found to be the most efficient methods, eliminating 100% of the carbon black content on the surface of the recovered carbon fibers. Finally, SEM evaluations and XPS analysis were conducted to compare the surface morphology and elementary constitution of the recovered carbon fibers with virgin carbon fibers.

Microstructure evolution and failure mechanism of 2D Cf/SiBCN–ZrB2 composite at elevated temperatures

SiBCN ceramic has already been widely used in the thermal insulation field. To further enhance their mechanical properties in high-temperature environments, the preparation of SiBCN and ZrB2 based pyrolytic carbon (PyC) modified carbon fiber reinforced composite, i.e., 2D Cf/SiBCN–ZrB2, was proposed in this study. By using five cycles of polymer impregnation and pyrolysis (PIP), the composite could be synthesized with a high flexural strength at room temperature, i.e., 275 ± 15 MPa. To understand the evolution of the microstructure caused by high temperatures and their influences on the mechanical properties, the composite samples were heat treated at 1200, 1400, 1600, and 1800 °C for 2 h, respectively. Comparing the flexural strengths of the samples before and after the heat treatments, and meanwhile combining the advanced microstructural characterizations, it was found that the composite was stable when the treating temperature was below 1400 °C, i.e., the flexural strength was 250 ± 15 MPa with a strength retention rate of over 90 %. However, once the temperature was above 1600 °C, due to the crystallization of SiBCN–ZrB2 matrix, the pyrolysis of PyC interfaces, the carbothermal reduction reaction and the erosion of carbon fibers, the mechanical properties of the composite would reduce to 74 ± 9 MPa. This study provides a new method for preparing 2D Cf/SiBCN–ZrB2, which reduces the number of PIP cycles of composite materials and enables rapid prototyping of composite materials. Additionally, this research can help materials scientists understand the mechanical properties of 2D Cf/SiBCN–ZrB2 composite materials in high-temperature environments and the evolution of their microstructure, identifying the range of application temperatures for 2D Cf/SiBCN–ZrB2.

Further understanding of the improved mechanical properties for SiCf/BN/SiC composites prepared by CVI+PIP hybrid technique: Application of micro-mechanical methods

In this work, a chemical vapor infiltration (CVI) combined with polymer impregnation and pyrolysis (PIP) technique was used to prepare high-performance SiCf/BN/SiC composites. Compared with the SiCf/BN/SiC composite fabricated by conventional PIP technique, the SiCf/BN/SiC composite fabricated by CVI + PIP hybrid technique showed the significantly improved flexural strength and toughness. The microstructures, macro-mechanical and micro-mechanical properties were systematically investigated and compared. By applying various micro-mechanical tests (fiber push-in, micropillar compression and micropillar splitting), the in-situ mechanical parameters of different micro-zones for SiCf/BN/SiC composites were obtained accurately. Based on the characterization results of microstructures and micro-mechanical properties, the corresponding toughening process was analyzed in combination of the classical He-Hutchinson criterion. The results indicate that the micro-mechanical test methods can provide accurate and effective data for the analysis of toughening and fracture process, presenting great potentials in the further understanding of the improvement in mechanical properties of ceramic matrix composites.