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1.
TiO2 nanofillers (5 nm, 0–15% weight) have been introduced in the PMMA matrix using a twin screw extruder to increase the performance of PMMA. The twin screw extrusion process is optimized to disperse the particles into PMMA. Nanofiller infusion improves the thermal, mechanical, and UV absorption properties of PMMA. TiO2‐PMMA nanocomposites exhibit the increase in tensile modulus (?90%), decomposition temperature (?31%), dimension stability (~ 60%) and UV absorption (~ 410%). Properties of the nanoTiO2‐PMMA composites are depending on the dispersion of TiO2 in the PMMA matrix. It is interrelated with loading. Formation and disappearance of the peaks in FTIR confirm the chemical interaction of PMMA with TiO2. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010  相似文献   

2.
The nylon 6‐based composite materials containing untreated and surface‐treated TiO2 particles with 3‐aminopropyltriethoxysilane (APTEOS), as coupling agent were prepared by in situ anionic polymerization of ε‐caprolactam in the presence TiO2 as a filler using the rotational molding technique. The thermal behavior and mechanical properties of the neat nylon 6 and its composites were investigated using various techniques such as differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), dynamic mechanical analysis (DMA), a tensile and flexural test and impact strength. Experimental results revealed that both untreated and surface‐modified TiO2 had distinct influence on the melting temperature (Tm), crystallization temperature (Tc), and degree of crystallinity (αDSC), thermal stability, storage modulus (E′), and loss factor (tan δ), and mechanical properties of nylon 6 matrix. Dynamical mechanical analysis indicated that addition of TiO2 particles into nylon 6 matrix increased both the storage modulus and the glass transition temperature. The corresponding values of nylon 6 composites with modified filler were higher than that of nylon 6 composite with untreated TiO2 particles. Tensile and flexural characteristics of the nylon 6 composites were found to increase while the elongation at break and impact strength with increase in TiO2 concentration relative to neat nylon 6. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers  相似文献   

3.
《Ceramics International》2019,45(13):16078-16087
Polymer-ceramic hybridization is an important method for preparing functional materials. Strontium titanate (SrTiO3, ST), a typical perovskite ceramic, has been widely applied in the electronics industry and photocatalytic fields. However, ST was barely reported to be utilized in cool materials. Herein, ST ceramic, as a solar reflective pigment, was introduced into a polymer matrix to prepare cool material. Specifically, the influences of both weight contents and surface grafting modification about ST on the properties of poly(methyl methacrylate) (PMMA)/ST composites were investigated, which include cooling performance, surface roughness, thermal emissivity, dispersion of particles and mechanical strength. The obtained composites containing 20 wt% unmodified ST possess excellent cooling property due to high thermal emissivity (86.8%, in 8–13 μm) and high solar reflectance (70.7%, in the whole solar band) which increased by 142% than that of pure PMMA resin. Temperature test highlighted that the composites containing 20 wt% unmodified ST was only 26.6 °C, 11.4 °C lower than that of PMMA resin and only 2 °C higher than initial temperature. Moreover, the surface grafting modification of ST by the silane coupling agent was proved to improve the dispersibility of ST in PMMA resin. Both the cooling and mechanical properties of composites containing modified ST particles were further improved. Though the solar reflectance of PMMA/ST composites was lower than that of PMMA/TiO2 composites, temperature tests showed that the PMMA/ST composites had a similar cooling performance with the PMMA/TiO2 composites when the content of the ceramic particles were 5.8 v%. This work not only prepared the polymer-ceramic hybrid materials with excellent cooling performance but also expanded the application of ST ceramic in the field of composites.  相似文献   

4.
High-refractive index polymeric materials, which are transparent, have many promising applications in optical design and advanced optoelectronic fabrication. In order to improve the refractive index of polymeric materials, inorganic materials with high-refractive index, such as TiO2, are always added into polymers. However, some of the traditional synthetic methods are complicated and hard to control. In our work, we developed a novel and simple method, a one-step in situ solvothermal method, to prepare poly(methyl methacrylate) (PMMA) and nano-TiO2 hybrid films. Methyl methacrylate (MMA), vinyltrimethoxysilane (VTMO), titanium butoxide [Ti(OBu)4], ethanol, hydrochloric acid, azobis-isobutyronitrile and tetrahydrofuran were added into a reaction vessel altogether and the polymerization of PMMA matrix and the formation of nano-TiO2 composite carried out simultaneously. To improve the adhesion between PMMA and TiO2, VTMO was used as a comonomer. The results indicate that TiO2 nanoparticles produced by decomposition of titanium butoxide are dispersed homogeneously in the PMMA matrix. The size of TiO2 crystals in PMMA/TiO2 nanocomposites is about 5–6 nm. The hybrid films have a good transparency (over 80 %) in the visible region, a good thermal stability and a UV-shielding property after the incorporation of TiO2. The refractive index of as-formed PMMA/TiO2 nanocomposites increases up to 1.839 at 633 nm as the content of Ti(OBu)4 is 50.00 wt%.  相似文献   

5.
Hybrid coatings (inorganic‐organic) were prepared using a blown and epoxidized soybean oil as the organic matrix. Both TiO2 particles and titanium sol‐gel precursors (Titanium tetra‐i‐propoxide, TIP; titanium (di‐i‐propoxide) bis(acetylactonate), TIA) were incorporated into the coating. Three sizes of TiO2 particles ranging from 32 nm to 500 nm were used for comparison with the metal‐oxo‐clusters. General mechanical coating properties, tensile properties, and viscoelastic properties of the sol‐gel (ceramer) system were evaluated for the coatings, and the sol‐gel derived metal‐oxo‐clusters were found to have higher tensile modulus, storage modulus (E ′), and Tg compared with the TiO2 particles.  相似文献   

6.
Different proportions of nanoscale TiO2 (nano‐TiO2)‐filled polybutylene succinate (PBS) composites were prepared by vane extruder. The crystalline, thermal, dynamic viscoelastic, mechanical, and UV‐resistance properties of the composites were studied, and X‐ray diffraction, differential scanning calorimetry, and thermogravimetric analysis were conducted. Results show that the crystalline structure of the PBS composites did not change with TiO2 addition. TiO2 almost has no effect on the crystallization and melting behavior of PBS. Nevertheless, the introduction of TiO2 has improved the thermal stability, tensile modulus, flexural modulus, and flexural strength of the PBS composites. The UV resistance of the composites has also been significantly enhanced with TiO2 addition. POLYM. COMPOS., 35:53–59, 2014. © 2013 Society of Plastics Engineers  相似文献   

7.
This study examines for the first time how matrix crosslinking affects the composite physical and mechanical properties of a graphite fiber reinforced PMR polyimide composite during long-term isothermal aging. Unidirectional composite specimens of Celion 6000/PMR-P1 were isothermally exposed at 288°C in air for various time periods up to 5000 h. The matrix crosslink densities were estimated from the kinetic theory of rubber elasticity and shifts in the glass transition temperatures (Tgs). The Tg, coefficient of thermal expansion, density, weight loss, moisture absorption, and elevated temperature flexural and interlaminar shear properties were also determined. Several linear relationships were found between the matrix crosslink density and composite physical and mechanical properties. The Tg, initial weight loss and density, and elevated temperature interlaminar shear strength increase with an increase in crosslink density. Conversely, the initial moisture absorption and coefficient of thermal expansion decrease with increasing crosslink density. As expected, the elevated temperature flexural strength and modulus show no direct correlations with crosslink density. Further, after achieving the highest matrix crosslink density, several of the composite properties begin to decrease rapidly. These findings suggest that time-temperature dependent nature of attaining the maximum matrix crosslinking is closely linked to the onset of the composite property degradation. Though much more work is needed, a fundamental understanding of the relationships between matrix crosslinking and composite physical and mechanical property can provide a scientific basis for the prediction of the extent of composite service life not only for PMR polyimides but also for other thermosetting matrix resins, such as epoxies and bismaleimides.  相似文献   

8.
BACKGROUND: Poly(methyl methacrylate) (PMMA)–organoclay nanocomposites with octadecylammonium ion‐modified montmorillonite, prepared via melt processing, over a wide range of filler loading (2–16 wt%) were investigated in detail. These hybrids were characterized for their dispersion structure, and thermal and mechanical properties, such as tensile modulus (E), break stress (σbrk), percent break strain (εbrk) and ductility (J), using wide‐angle X‐ray diffraction, transmission electron microscopy, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and tensile and impact tests. RESULTS: Intercalated nanocomposites were formed even in the presence of 16 wt% clay (high loading) in PMMA matrix. PMMA intercalated into the galleries of the organically modified clay, with a change in d‐spacing in the range 11–16 Å. TGA results showed improved thermal stability of the nanocomposites. The glass transition temperature (Tg) of the nanocomposites, from DSC measurements, was 2–3 °C higher than that of PMMA. The ultimate tensile strength and impact strength decreased with increasing clay fraction. Tensile modulus for the nanocomposites increased by a significant amount (113%) at the highest level of clay fraction (16 wt%) studied. CONCLUSION: We show for the first time the formation of intercalated PMMA nanocomposites with alkylammonium‐modified clays at high clay loadings (>15 wt%). Tensile modulus increases linearly with clay fraction, and the enhancement in modulus is significant. A linear correlation between tensile strength and strain‐at‐break is shown. Thermal properties are not affected appreciably. Organoclay can be dispersed well even at high clay fractions to form nanocomposites with superior bulk properties of practical interest. Copyright © 2007 Society of Chemical Industry  相似文献   

9.
《Ceramics International》2022,48(10):13770-13779
A wollastonite-nanoTiO2 composite (WOT-PC) was prepared by a facile mechanochemistry method, which is expected to improve the photocatalytic performance and its recycling ability. According to the results of photocatalytic degradation, the degradation extent of the 10 ppm (10 mg/L) methyl orange solution was 99% after 20 min UV irradiation, indicating the good photocatalytic performance of WOT-PC. The XPS results suggests that stable Ca–O–Ti and Si–O–Ti bind wollastonite and nanoTiO2 together chemically. Furthermore, Ca–O–Ti may promote the separation efficiency of photoinduced electrons and holes during irradiation. To study the bending of energy structures of nanoTiO2, UPS was used. The results showed a negative shift of the energy structure bands and a positive shift of the Fermi level to TiO2, revealing that electrons more easily move to the surface of TiO2 after wollastonite supports nanoTiO2. The WOT-PC coating exhibits great self-cleaning ability because of its superhydrophilicity and photocatalytic performance, reflecting the promise of WOT-PC as an outdoor wall coating in practical applications.  相似文献   

10.
Comparing the thermal properties of TiO2 encapsulating polystyrene and poly(methyl methacrylate) with those of TiO2 dispersion polymers it was found that the encapsulating polymers have two thermal relaxation regions. The activation energy of those thermal relaxation regions was determined using the Wunderlich method and it was found that the values are similar to the activation energy for the dynamic dispersion. It is suggested that the low-temperature thermal relaxation is caused by the local change of conformation of molecular chains, while the high-temperature thermal relaxation is similar to that of the normal glass transition temperature including the interaction with TiO2. In addition, the thermal behaviour near the degradation point in different atmospheres indicates that the encapsulating polymer has a specific structure for adsorbing a large amount of oxygen.  相似文献   

11.
The effects of quenching temperature including different thermal histories on mechanical, physical, and thermal properties of pigmented polycarbonate (PC/TiO2) were investigated. Tensile test, Izod impact strength and heat distortion temperature (HDT) were performed on specimens of 3 mm thickness. Pigment content and quenching temperature are two key factors that affect the properties of the materials. A higher content of pigments results in an increase of modulus of elasticity and a decrease of unotched and notched Izod impact strength, as well as elongation at break. A maximum of yield stress and HDT is obtained at 3% of TiO2, which was considered as the optimum level of pigment. An additional second quenching at 40°C has allowed to improve Izod impact strength and elongation at break of specimens with 3% of TiO2; whereas modulus of elasticity, density, yield stress, and HDT were minimum at this quenching temperature. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007  相似文献   

12.
Herein, a strategy of embedding in-situ polymethyl-methacrylate (PMMA) domains in polydimethylsiloxane (PDMS) networks is proposed to enhance adhesive and damping properties of addition type silicone rubber (SR). PMMA domains improve the modulus of SR (at room temperature), which is stronger correlated to its adhesive performance, according to the Griffith criterion. Besides, the damping performance at high temperature is provided by the glass transition of thermoplastic PMMA. The PMMA/SR blends are obtained by the crosslink of PMMA and vinyl-terminated polydimethylsiloxane (vi-PDMS) liquid blends with polymethylhydrosiloxane, and the PMMA/vi-PDMS liquid blends are prepared by in-situ radical polymerization of methyl-methacrylate (MMA) in vi-PDMS with toluene as compatibilizer. Effects of disperse speed, compatibilizer content, and PMMA proportion on the morphologies and properties of PMMA/SR blends are studied. Small PMMA domains (around 800 nm) in PMMA/vi-PDMS blends with narrow size distribution and well dispersion are formed at appropriate disperse speed (100–300 rpm) and abundant compatibilizer content (~100 wt% refers to vi-PDMS). The blends with 20 wt% PMMA possess tensile strength over 8 MPa and lap shear strength over 5 MPa to stainless steel. And the blends with 50 wt% PMMA show good damping properties with tan δ over 0.15 at temperature range from −50 to 150°C. Tg-PMMA moves slightly to lower temperature with less PMMA embedded, but Tg-PDMS remained stable relatively.  相似文献   

13.
To improve the physical properties of plasticized poly(vinyl chloride) (p‐PVC), the p‐PVC nanocomposites filled with four loading levels (3, 5, 7, and 9 parts per hundred of PVC resin) of either nanosized titanium dioxide (nTiO2) or poly(methyl methacrylate)–encapsulated nTiO2 (PMMA‐nTiO2) were prepared by melt mixing on a two‐roll mill, followed by compression molding. The PMMA‐nTiO2 used in this study was synthesized via in situ differential microemulsion polymerization. The resulting PMMA‐nTiO2 exhibited core‐shell morphology (nTiO2 core and PMMA shell) with an average diameter of 42.6 nm. The effects of nTiO2 and PMMA‐nTiO2 on the tensile properties, hardness, morphology, and thermal stability of the as‐prepared p‐PVC nanocomposites were then investigated and compared. The inclusion of either nTiO2 or PMMA‐nTiO2 nanoparticles increased the tensile strength, Young's modulus, hardness, and thermal stability of the nanocomposites in a dose‐dependent manner and reduced the elongation at break. However, the elongation at break was still higher than that for the neat p‐PVC. Moreover, the PMMA‐nTiO2 nanocomposites had a higher enhancement of the tensile strength, Young's modulus, hardness, and thermal stability than the nTiO2 nanocomposites at a similar loading level. Hence, the PMMA grafted on the nTiO2 surface played an important role in toughening and increasing the thermal stability of the nanocomposites owing to the improved miscibility and interfacial adhesion between the encapsulated nanofiller and PVC matrix. J. VINYL ADDIT. TECHNOL., 22:433–440, 2016. © 2015 Society of Plastics Engineers  相似文献   

14.
Commercial Poly(methyl methacrylate) (PMMA) containing Tinuvin 622, a Hindered Amine Stabilizer (HAS), in 0.3% (wt/wt) concentration was investigated. The samples were irradiated with gamma radiation (60Co) at room temperature in air. The viscosity‐average molecular weight (Mv) was analyzed by viscosity technique. Both control PMMA (without HAS) and PMMA + 622 (with HAS) showed a decrease in molecular weight with the increase in dose, reflecting the random scissions that occurred in the main chain. The G value (scissions/100 eV of energy transferred to the system) was also obtained by viscosity analysis. G value results showed that the addition of Tinuvin 622 into the PMMA matrix significantly decreased the number of scissions/100 eV at dose range of 0–60 kGy. Analysis of infrared spectra showed a decrease in the carbonyl index (CI) in irradiated samples. However the CI decrease was found lower for PMMA + 622 than for control PMMA sample. Thermogravimetric analysis (TGA) revealed that maximum decomposition temperature of additive PMMA is 42°C higher than control PMMA for unirradiated system. On the other hand this difference is not significant in irradiated systems at 60‐kGy irradiation dose. The activation energy of the thermal degradation of PMMA was 165 kJ/mol, this activation energy increased 60 kJ/mol when Tinuvin 622 was added to PMMA matrix. Therefore Tinuvin 622 is a suitable radiostabilizing agent for commercial PMMA in a 0–60 kGy dose interval. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008  相似文献   

15.
Three types of nonmetallic mineral particles (CaCO3, TiO2 and loess) were incorporated into waterborne polyurethane acrylate (PUA) to improve the surface properties of ecofriendly floor tiles. Several properties of PUA containing nonmetallic mineral materials were measured by Fourier transform infrared spectroscopy (FT-IR), a dynamic mechanical thermal analyzer (DMTA), swelling tests, and contact angle measurement. Upon decreasing the molecular weight between crosslinks (variation of molecular weight of the polyol), the modulus and glass transition temperature (Tg) of the PUA film increased because of the increase in crosslinking density. Resistance properties such as swelling and contact angle against water were enhanced with the addition of nonmetallic mineral particles because of the increase in the hydrophobic nature of the polymer matrix.  相似文献   

16.
This paper deals with the thermal and thermal-oxidative degradation of pure poly(methyl methacrylate) (PMMA), PMMA/A1N and PMMA/Al2O3 composites. Kinetic parameters were determined from the weight loss data using non-isothermal Thermogravimetric Analysis (TGA). The amount and morphology of the carbon residue in the burnt samples under N2 and air atmospheres were also investigated using a Leco combustion analyzer. This study also showed that the normally accepted three-stage polymer thermal degradation, and hence three regions of Arrhenius linearity, can be treated with one value of activation energy. This is a basic departure from the normally accepted three different regions and applying the same diffusion equation (such as Jander diffusion) separately to each region. In nitrogen atmosphere, the activation energy of pure PMMA was 129.4 kJ/mol; however, the activation energies of 14% PMMA/AlN and PMMA/Al2O3 were found to be 119.5 and 118.2 kJ/mol, respectively.  相似文献   

17.
A facile route was adopted to blend the matrix. The PMMA/PEG blend was reinforced with three types of nanofillers, i.e., pristine MWCNT (P-CNT), amine functionalized MWCNT (PDA-EA-CNT) and nanobifiller i.e. nanodiamond functional MWCNT (PDA-EA-CNT-ND) to yield three different types of nanocomposites i.e. PMMA/PEG/P-CNT, PMMA/PEG/PDA-EA-CNT and PMMA/PEG/PDA-EA-CNT-ND. These nanocomposites were reinforced with nanofiller loading (1 wt. %, 3 wt. %, 5 wt. %, 10 wt. %, 30 wt. % and 50 wt. %) by solution casting method. Structure of composite and nanofillers was confirmed by FTIR. FESEM imaging revealed that nanocomposites have micro porous morphology. At high magnification, distribution of functionalized CNT/ND appears to be protruding out of the polymeric matrix. The TGA result suggests that the thermal stability of the nanocomposites was enhanced in comparison to PMMA due to grafting of filler molecules with PMMA/PEG macromolecules. The DTG results showed that the bifiller nanocomposites (PMMA/PEG/PDA-EA-CNT-ND) exhibited improved thermal stability with Tmax (431°C) as compared to P-CNT and amine functionalized CNT (PMMA/PEG/PDA-EA-CNT) with Tmax of 395°C and 418°C respectively. XRD results showed fine interaction between filler and the polymeric matrix. As the filler loading was increased the composites showed pronounced XRD peak at 25.9°, corresponding to (002) reflection of nanotubes. Significant improvement in the mechanical properties of composites was recorded with the reinforcement of fillers as compared to the neat matrix. The most significant improvement in tensile strength and elastic modulus was observed for the bifiller nanocomposites with 5 wt. % PDA-EA-CNT-ND. They showed a tensile strength and elastic modulus of 29.9 MPa and 1474.31 MPa respectively as compared to amine functionalized CNT with tensile strength (25.7) and elastic modulus (1466.99 MPa)and P-CNT with tensile strength(25 MPa) and elastic modulus (1155.75 MPa).  相似文献   

18.
TiO2‐doped Y2O3‐stabilized ZrO2 compounds with low thermal conductivity have been considered as a promising thermal barrier coating material. In the present research, a series of TiO2‐doped Y2O3‐stabilized ZrO2 compounds have been synthesized and investigated. Lattice distortion and disordering caused by TiO2 doping were observed and their effects on mechanical properties, such as fracture toughness, elastic modulus, and coefficient of thermal expansion (CTE), were also investigated. Lattice distortion enhanced the ferroelastic toughening and the fracture toughness, whereas the variation in elastic modulus and CTE is due to the lattice disordering. The combination of thermal and mechanical properties bodes well for the potential application as thermal barrier coating materials.  相似文献   

19.
The structure and properties of a preimidized photosensitive polyimide (Probimide PSPI, a copolyimide of benzophenonetetracarboxylic dianhydride with alkyl groups substituted aromatic diamines) were studied with variations of UV exposure energy and bake temperature by means of wide angle X-ray diffraction, dynamic mechanical thermal analysis, stress-strain analysis, and residual stress analysis. The X-ray diffraction patterns patterns indicate that the PSPI is amorphous in the solid state. The Tg was 378°C ~ 410°C, depending upon the thermal history over the range of 350°C ~ 400°C. At the glass transition region, the dynamic storage modulus E′ was very sensitive to both i-line exposure energy and thermal history. However, the mechanical stress-strain behavior at room temperature was primarily dependent on the thermal history. The mechanical properties were 2.6 GPa ~ 2.9 GPa Young's modulus, 131 MPa ~ 168 MPa tensile strength, 10% ~ 12% yield strain, and 16% ~ 74% elongation at break, depending upon the baking or annealing. These dynamic and static mechanical properties indicate that on the PSPI backbone, crosslinks are formed thermally as well as photochemically. The thermal crosslinks might be formed through thermal liberation of the labile alkyl groups of aromatic diamine moieties and subsequent coupling of the radicals. The thermal degradation was also evidenced in the mechanical properties degraded by baking above 375°C or annealing above 350°C. In addition, during baking and cooling, the residual stress was dynamically measured on Si wafers as a function of temperature. The stress at room temperature was 48 MPa ~ 52 MPa for the PSPI films baked at 350°C or 400°C, regardless of i-line exposure.  相似文献   

20.
Ying Xia 《Polymer》2010,51(12):2508-709
Two castor oil-based monomers, (1) norbornenyl-functionalized castor oil (NCO), which has ∼0.8 norbornene rings per fatty acid chain and (2) norbornenyl-functionalized castor oil alcohol (NCA), which has ∼1.8 norbornene rings per fatty acid chain, have been prepared. Ring-opening metathesis polymerization (ROMP) of different ratios of NCO/NCA using the 2nd generation Grubbs catalyst results in rubbery to rigid biorenewable-based plastics with crosslink densities ranging from 318 to 6028 mol/m3. Increased crosslink densities result in shorter gelation times, better incorporation of the monomers into the polymer network, and much less soluble materials in the bulk materials. The increased crosslink densities obtained by adding NCA enhance the thermal properties, including the glass transition temperature (Tg) and room temperature storage modulus, which increase from −17.1 °C to 65.4 °C and from 2.4 MPa to 831.9 MPa, respectively. The TGA results, where T10 increased from 285 °C to 385 °C, illustrate that improved thermal stabilities can be obtained for thermosets with higher crosslink densities. Young’s modulus (11-407 MPa), tensile strength (1.6-18 MPa) and toughness (0.14-1.6 MPa) are also improved dramatically with higher crosslink densities.  相似文献   

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