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1.
As an additive manufacturing technology, ultraviolet (UV)‐curing three‐dimensional printing, which requires the use of a photocurable resin, is increasingly being used to produce customized end‐user parts of many complex shapes. In this study, to improve the strength and ductility of printing materials, nano‐SiO2‐reinforced photocurable resins were prepared by a planetary ball mill; then, the morphology, photochemistry, thermal property, and mechanical properties of the nanocomposites were investigated and characterized. Transmission electron microscopy analysis indicated that the modified nano‐SiO2 was well dispersed in the photocurable resin. The glass‐transition temperature increased from 67.2°C for the unfilled resin to 71.7 and 80.1°C for nanocomposites with nano‐SiO2 contents of 0.3 and 0.7 wt %, respectively. The tensile strength and impact strength were increased by 46.7 and 165.3% for nanocomposites with 0.3 wt % nano‐SiO2. The flexural modulus of the nanocomposites increased from 1.7 to 8.0 GPa when 0.7 wt % nano‐SiO2 was added to the photocurable resin; this appeared to originate from the relatively high level of dispersion and the intimate combination of the nano‐SiO2 with the matrix. The investigation of the physical and chemical properties of such UV‐curing materials showed that the low filler concentration (<1 wt %) of nano‐SiO2 did not affect the processability of the nanocomposites. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42307.  相似文献   

2.
《Polymer Composites》2017,38(10):2261-2271
High‐performance nanosilica composites based on epoxy‐modified polybenzoxazine matrices are developed. Chemorheological study of benzoxazine–epoxy resin mixtures reveals that processing window of the benzoxazine resin (BA‐a) is substantially broadened with an addition of the liquid epoxy. Glass transition temperature (T g) of the BA‐a copolymerized with epoxy resin shows a synergistic behavior with a maximum T g value (174°C) at the benzoxazine–epoxy mass ratio of 80:20. The copolymer at this composition is also used as a matrix for nano‐SiO2 composites. A very low melt viscosity of the benzoxazine–epoxy mixtures promotes good processability with the maximum attainable nano‐SiO2 loading up to 35 wt%. From scanning electron microscopy investigation, fracture surface of the 35 wt% nano‐SiO2‐filled benzoxazine–epoxy composite reveals relatively homogeneous distribution of the nano‐SiO2 in the copolymer with good particle wet‐out. In addition, very high reinforcing effect was also observed in such high content of the nano‐SiO2, i.e., about 2.5 times in modulus improvement. This improvement is attributed to the strong bonding between the copolymer matrix and the nano‐SiO2 through ether linkage as confirmed by Fourier‐transform infrared investigation. POLYM. COMPOS., 38:2261–2271, 2017. © 2015 Society of Plastics Engineers  相似文献   

3.
Crosslinked alginate‐based nanocomposites at different SiO2 contents were prepared successfully by blending the nano‐SiO2 solution into low concentration alginate solution (0.5 wt %), with the alginate concentration increased step by step to the resulted concentration, in this course glycerol was used as plasticizer and 5 wt % CaCl2 as crosslinker. The combined effect of SiO2 content (1.5–8 wt %) on the microstructural, physical, mechanical, and optical properties of the nanocomposite films were investigated. The results showed that tensile strength and elongation was improved by about 40.33% and 89%, respectively, upon increasing the SiO2 content to 4.5 wt %. In addition, water vapor permeability and swelling degree decreased by 19% and 16% with increasing SiO2 content up to 8 and 4.5 wt %, respectively with respect to pure crosslinked alginate film. Thermogravimetric analysis also revealed that nano‐SiO2 can improve the thermal stability of sodium alginate films produced by this method. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45286.  相似文献   

4.
A novel phosphorus‐containing poly (ethylene terephthalate) (PET) copolyester/nano‐SiO2 composite (PET‐co‐DDP/SiO2) was synthesized by in situ polycondensation of terephthalic acid (TPA), ethylene glycol (EG), [(6‐oxide‐6H‐dibenz[c,e] [1,2]oxaphosphorin‐6‐yl)‐methyl]‐butanedioic acid (DDP), and nano‐SiO2. The morphology of PET nanocomposites was observed by using transmission electron microscope and scanning electron microscope. It was found that the SiO2 nanoparticles were dispersed uniformly at nanoscale in the copolyesters with content 2 wt %. The thermal degradation behavior of PET nanocomposites was investigated by thermogravimetric analysis performed with air and nitrogen ambience. The activation energies of thermal degradation were determined using Kissinger and Flynn–Wall–Ozawa methods, respectively. The results obtained from Kissinger method showed that the activation energy was increased with the introduction of SiO2. Moreover, the activation energy is decreased for PET‐co‐DDP system in nitrogen and air. The results also indicated that the SiO2 and DDP had synergic effect on the early decomposition and the late charring in air. Furthermore, in the PET‐co‐DDP/SiO2 system, the activation energy increased when the DDP component increased. However, the opposite results were obtained when the Flynn–Wall–Ozawa method was used. That was because the Doyle approximation stands correct as the conversion degree is from 5% to 20%. The effects of SiO2 and DDP on the PET thermal degradation were lower in nitrogen than in air. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011  相似文献   

5.
The effects of heat treatment on the crystal structure and impact strength of poly(phenylene sulfide) (PPS) and nano‐SiOx/ PPS nanocomposites were studied. The molecular weight of heat‐treated neat PPS was increased by 28% due to the crosslinking reaction that changed its crystal morphology. Also, the crystallinity was reduced by 18%, leading to an improvement of the Izod impact strength by 66%. Nano‐SiOx/PPS composites were manufactured by intensive compounding with 3 wt.‐% nano‐SiOx particles treated by an epoxy functional group. Test results showed that the Izod impact strength of nano‐SiOx/heat‐treated PPS composites was 91% better and the crystallinity 27% less compared to the same properties of “as received” neat PPS. Nano‐SiOx has a high specific surface area and a high surface energy; its grafted epoxy group promotes interfacial adhesion with the PPS matrix, hence increasing the Izod impact strength of the nanocomposites.

TEM micrograph of NHTM‐PPS with 3 wt.‐% nano‐SiOx.  相似文献   


6.
Comprehensive high‐performance epoxy nanocomposites were successfully prepared by co‐incorporating organo‐montmorillonite (o‐MMT) and nano‐SiO2 into epoxy matrix. Because of the strong interaction between nanoscale particles, the MMT layers were highly exfoliated, and the exfoliated nanoscale MMT monoplatelets took an interlacing arrangement with the nano‐SiO2 particles in the epoxy matrix, as evidenced by X‐ray diffraction measurement and transmission electron microscopy inspection. Mechanical tests and thermal analyses showed that the resulting epoxy/o‐MMT/nano‐SiO2 nanocomposites improved substantially over pure epoxy and epoxy/o‐MMT nanocomposites in tensile modulus, tensile strength, flexural modulus, flexural strength, notch impact strength, glass transition temperature, and thermal decomposition temperature. This study suggests that co‐incorporating two properly selected nanoscale particles into polymer is one pathway to success in preparing comprehensive high‐performance polymer nanocomposites. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012  相似文献   

7.
A new type of polybenzoxazine‐clay nanocomposites were prepared by the in‐situ polymerization of allyl‐functional benzoxazine monomer, bis(3‐allyl‐3,4‐dihydro‐2H‐1,3‐benzoxazinyl)isopropane (B‐ala), in the presence of two different types of organoclay, allyldimethylstearylammonium‐montmorillonite and propyldimethylstearylammonium‐montmorillonite. The organoclays were mixed with molten B‐ala, followed by pouring into glass mold and then gradual curing up to 250°C. DSC and IR were used to follow the cure behavior of B‐ala in the presence of organoclay, indicating that organoclays catalyzed the ring opening of cyclic benzoxazine structure. The XRD of the nanocomposites showed featureless patterns, suggesting the exfoliation of the organoclay into the matrix. The viscoelastic properties of the hybrids showed that the glass transition temperatures (Tg) of the nanocomposites shifted to lower temperature in the presence of small amount of organoclay, but Tg started to increase with the increase of the organoclay content. This result suggests that, in the presence of organoclay, the curing reaction of ally and benzoxazine occurred in a different way, resulting in a different network structure. However, the presence of dispersed layered silicates into the matrix enhanced the thermal stability over the neat thermoset resin. POLYM. COMPOS., 2008. © 2008 Society of Plastics Engineers  相似文献   

8.
Nanoreinforcing fillers have shown outstanding mechanical properties and widely used as reinforcing materials associated to polymeric matrices for high performance applications. In this study, a series of multiwalled carbon nanotubes (MWCNTs)‐, nano‐Al2O3‐, nano‐SiO2‐, and talc‐reinforced epoxy resin adhesives composites were developed. The influence of different types and contents of nanofillers on adhesion, elongation at break, and thermal stability (under air and nitrogen atmospheres) of diglycidyl ether of bisphenol A (DGEBA)/epoxy novolac adhesives was investigated. A simple and effective approach to prepare adhesives with uniform and suitable dispersion of nanofillers into epoxy matrix was found to be mechanical stirring combined with ultrasonication. Transmission electron microscopic and scanning electron microscopic investigations revealed that nanofillers were homogeneously dispersed in epoxy matrix at optimized nanofiller loadings. Adhesion strength was measured by lap shear strength test as a function of nano‐Al2O3 and MWCNTs loadings. The results indicated that the lap shear strength was significantly increased by about 50% and 70% with addition of MWCNTs and nano‐Al2O3 up to a certain level, respectively. The highest lap shear strength was reached at 1.5 wt % of nano‐Al2O3 loading. MWCNTs at all loadings (except 3 wt %) and nano‐Al2O3 have enhanced onset of degradation temperature and char yield of the adhesives. By combined incorporation of 0.75 wt % nano‐Al2O3 and 0.75 wt % MWCNTs into the epoxy novolac/DGEBA blend adhesives a synergistic effect was observed in the thermal stability of the adhesives at high temperatures (800°C). © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2014 , 131, 40017.  相似文献   

9.
Ball milling and mixing with strong shear force and strike force were applied to get fine dispersion of nano‐SiOx particles in poly(phenylene sulfide) (PPS) powder. Nano‐SiOx/PPS composites were manufactured by intensive compounding with 3 wt% nano‐SiOx particles. Effects of the ball milling dispersion on crystal behavior and impact strength of nano‐SiOx/PPS nanocomposites were studied. Physical mechanisms of ball milling dispersion were investigated. Evaluations based on both WAXD and DSC indicates that crystallization behavior of nano‐SiOx/heat‐treated PPS (HT‐PPS) nanocomposites was influenced by the ball milling process. Their crystallinity was 25% less while Izod impact strength was 89% better than those of as‐received neat PPS. Increased kinetic energy via ball milling by external work makes nano‐SiOx able to overcome the attraction from itself to prevent agglomeration. Interfacial bonding of two phases between nano‐SiOx and PPS was enhanced by crosslinking in HT‐PPS and reduction in surface tension of interface during ball milling. The bonds allow SiOx to dissipate energy and thus improve PPS impact strength from the addition of nano‐SiOx. POLYM. ENG. SCI., 46:820–825, 2006. © 2006 Society of Plastics Engineers  相似文献   

10.
New amide–acid functional SiO2 nanoparticle (FSNP)‐reinforced semi‐crystalline aliphatic–aromatic poly(ether‐sulfone‐amide) (PESA) was synthesized using a solution method in dimethylformamide. The surfaces of SiO2 nanoparticles were functionalized with phthalic anhydride, and subsequently PESA was synthesized using direct polymerization with good yield and desired molar mass. PESA / SiO2 nanocomposites (PSNCs) were prepared with three different contents of FSNP and the morphology and mechanical, thermal and combustion properties of the PSNCs were studied. The results of X‐ray diffraction, field‐emission scanning electron microscopy and transmission electron microscopy showed a uniform dispersion for FSNP in the PESA matrix. According to the results of mechanical tests, the tensile strength and the Young's modulus of PESA were enhanced by FSNP loading. Thermogravimetric analysis and derivative thermogravimetry results showed a substantial improvement in thermal properties of PESA. The temperature at 5% mass loss was increased from 371.7 to 395.8 °C for the PSNC containing 8 mass% of FSNP, as well as the char yield being enhanced greatly, which was about 30% higher than that of neat PESA. Significant improvements in combustion properties were observed for PSNCs from microscale combustion calorimetry. The peak heat release rate showed an obvious improvement and decreased by about 57% compared to that of neat PESA on 8 mass% loading of FSNP. © 2016 Society of Chemical Industry  相似文献   

11.
Poly(vinyl chloride) (PVC)/SiO2 nanocomposites were prepared via melt mixture using a twin‐screw mixing method. To improve the dispersion degree of the nanoparticles and endow the compatibility between polymeric matrix and nanosilica, SiO2 surface was grafted with polymethyl methacrylate (PMMA). The interfacial adhesion was enhanced with filling the resulting PMMA‐grafted‐SiO2 hybrid nanoparticles characterized by scanning electron microscopy. Both storage modulus and glass transition temperature of prepared nanocomposites measured by dynamic mechanical thermal analysis were increased compared with untreated nanosilica‐treated PVC composite. A much more efficient transfer of stresses was permitted from the polymer matrix to the hybrid silica nanoparticles. The filling of the hybrid nanoparticles caused the improved mechanical properties (tensile strength, notched impact strength, and rigidity) when the filler content was not more than 3 wt %. Permeability rates of O2 and H2O through films of PMMA‐grafted‐SiO2/PVC were also measured. Lower rates were observed when compared with that of neat PVC. This was attributed to the more tortuous path which must be covered by the gas molecules, since SiO2 nanoparticles are considered impenetrable by gas molecules. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008  相似文献   

12.
To improve the impact toughness of polypropylene (PP), nano‐CaCO3 was prepared by an in situ synthesis. The surface of the nano‐CaCO3 was modified by KH‐550 silane coupling agent and NDZ‐401 titanium acid ester coupling agent. Nano‐CaCO3/PP composite materials were fabricated through a melt‐blending method and characterized, and their mechanical properties were analyzed. The impact toughness and the tensile strength of the PP were improved significantly by the incorporation of nano‐CaCO3. When the weight fraction of nano‐CaCO3 was 2%, the maximum impact toughness and tensile strength of the PP nanocomposites were 293% and 259%, respectively, of the values for neat PP. Observation of the impact fracture surface of the nanocomposites indicated that the dispersion of nano‐CaCO3 modified by NDZ‐401 coupling agent was more homogeneous than that of nano‐CaCO3 modified by the KH‐550 silane coupling agent. J. VINYL ADDIT. TECHNOL., 2009. © 2009 Society of Plastics Engineers  相似文献   

13.
A water‐dispersible conducting polyaniline/ nano‐SiO2 composite, with a conductivity of 0.071 S cm?1 at 25°C, was prepared by the oxidative polymerization of aniline in the presence of amorphous nano‐SiO2 particles. And the structure, morphology, thermal stability, conductivity, and electroactivity of this composite were also investigated. This composite has been steadily dispersed in the aqueous solution for about 10–36 h without the need for any stabilizer. It would significantly impulse the commercial applications of conducting polyaniline/nano‐SiO2 composite as fillers for antistatic and anticorrosion coatings. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008  相似文献   

14.
Poly(vinyl alcohol)/nano‐silica (PVA/nano‐SiO2) films were prepared through extrusion blowing with the addition of water and glycerin as plasticizer. The characteristic properties of PVA/nano‐SiO2 films were investigated by differential scanning calorimetry, dynamic mechanical analysis, Haake torque rheometry, and atomic force microscopy (AFM). The results showed that the mechanical properties of PVA/nano‐SiO2 were improved dramatically. The tensile strength of the nanofilms increased from 62 MPa to 104 MPa with loading 0.3 wt % nano‐SiO2 and the tear strength was improved from 222 KN/m to 580 KN/m. The crystallinity of the films loaded with 0.4 wt. % nano‐SiO2 decreased from 32.2% to 21.0% and the AFM images indicated that the amorphous region of nanofilms increased with increasing nano‐SiO2 content. The storage modulus and loss modulus increased to two and nearly three times with 0.3 wt % nano‐SiO2 loading. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013  相似文献   

15.
The organic–inorganic hybrid boron‐containing phenol–formaldehyde (BPFR) resin/SiO2 nanocomposites was synthesized in‐situ from boric acid, phenol, and tetramethoxysilane. The structure of BPFR modified and the distributions of silicon element were studied by Fourier‐transform infrared spectroscopy, energy dispersive X‐ray spectrometry, and transmission electron microscope, respectively. The glass transition temperature (Tg) was determined by torsional braid analysis. The results show that silicon element distribution is homogeneous, and the size of nanosilica is about 40–60 nm. The thermal stability and kinetics parameters of thermal degradation were determined by thermogravimetry analysis (TGA). TGA results show that the resin modified has higher heat resistance property when the additive quantity of SiO2 was 3 wt%. The temperature of 5% weight loss is 487.7°C, which is 12.4°C higher than that of common BPFR. The residual ratio of 3 wt% SiO2/BPFR was 62.3% at the temperature of 900°C, which is 11.2% higher than that of common BPFR. The mechanics loss peak Tp of 3% SiO2/BPFR is 33°C higher than common BPFR. Fiberglass‐reinforced BPFR modified by 3 wt% SiO2 has better mechanical and dielectric properties than that of common BPFR. POLYM. COMPOS., 2008. © 2007 Society of Plastics Engineers  相似文献   

16.
A series of copolyimide/SiO2 hollow sphere thin films were prepared successfully based on bis[3,5‐dimethyl‐4‐(4‐aminophenoxy)phenyl]methane and 9,9‐bis(4‐(4‐aminophenoxy)phenyl)fluorene (molar ratio = 3 : 1) as diamine, and 4,4′‐(4,4′‐isopropylidenediphenoxy)bis(phthalic anhydride) as dianhydride, with different wt % SiO2 hollow sphere powder with particle size 500 nm. Some films possessed excellent dielectric properties, with ultralow dielectric constants of 1.8 at 1 MHz. The structures and properties of the thin films were measured with Fourier transform infrared spectra, scanning electron microscope, thermogravimetric analysis, and dynamic mechanical thermal analysis. The polyimide (PI) films exhibited glass‐transition temperatures in the range of 209– 273°C and possessed initial thermal decomposition temperature reaching up to 413–477°C in air and 418–472°C in nitrogen. Meanwhile, the composite films were also exhibited good mechanical properties. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011  相似文献   

17.
Several bisphenol‐A benzoxazine (BEN) based nanocomposites incorporated with several polyhedral oligomeric silsesquioxane (POSS), carbon nanotubes (CNTs), and clays, were prepared successfully. The influences of the nanofillers on curing kinetics, network formation, and thermal stability of the BEN were investigated comprehensively. The addition of the nanofillers showed different influence on curing kinetics of BEN. Furthermore, the incorporation of the nanofillers showed good improvement on thermal stability of BEN. An increase of 70 and 336°C at the onset and the half‐life decomposition temperature were observed with the addition of 5 wt % 30B clay in nitrogen atmosphere. With the incorporation of 5 wt % POSS, the half‐life of decomposition and char yield enhanced by 280°C and 13 wt % in nitrogen atmosphere. For the 4 wt % MWCNT‐COOH/BEN nanocomposite, the half‐life of decomposition and char yield at 800°C increased by 286°C and 14 wt % in nitrogen atmosphere, respectively. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41903.  相似文献   

18.
A novel bisphthalonitrile containing benzoxazine units (BZ‐BPH) was synthesized via a solventless method from 4,4′‐dihydroxybiphenyl, paraformaldehyde, and 4‐aminophenoxylphthalonitrile. The chemical structure of BZ‐BPH was confirmed by 1H‐NMR and 13C‐NMR analyses. The curing behavior was investigated with DSC, FTIR, TGA, and rheology techniques. The monomer manifested a two‐stage thermal polymerization pattern. The first stage was attributed to the ring‐opening polymerization of benzoxazine moiety, and the second to the polymerization of phthalonitriles. Study about the effect of the catalysts including 4,4′‐diaminodiphenylsulfone and FeCl3 on the polymerization of BZ‐BPH was performed, and the result indicated that the addition of these agents could increase the curing rate and lower the curing temperature. Additionally, the cured product showed excellent thermal and thermo‐oxidative stability, the high char yield was 76.0% by weight at 800°C in nitrogen atmosphere and 81.2% by weight at 600°C in air, and temperature at 5% weight loss (T5%) in nitrogen and air was 477.9°C and 481.7°C, respectively. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010  相似文献   

19.
Ortho‐, meta‐, and para‐phenylnitrile–functional benzoxazines are polymerized at different compositions with phthalonitrile‐functional monomers providing copolybenzoxazines of high thermal stability and easy processability. The most positive effect on these properties is obtained on copolymerizing phthalonitrile‐ and ortho‐phenylnitrile–functional benzoxazines. Thermal decomposition of these polybenzoxazines is studied by thermogravimetry (TGA). It is demonstrated that only 30 mol % of phthalonitrile‐functional benzoxazine added to the ortho‐phenylnitrile–substituted monomer improves char yield significantly from 59 to 77 wt %, which is the value of neat phthalonitrile‐based polybenzoxazine. Glass transition temperature (Tg) also dramatically increases from 180°C for neat ortho‐phenylnitrile polymer to 294°C for the copolymer with 30 mol % of phthalonitrile‐functional monomer. Additionally, the high melt viscosity of phthalonitrile‐functional benzoxazines is dramatically decreased upon blending with phenylnitrile‐functional monomer. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 2937–2949, 1999  相似文献   

20.
Polystyrene/α‐zirconium phosphate (PS/OZrP) nanocomposites were prepared based on the organically modified α‐ZrP(OZrP) with hexadecyltrimethyl ammonium bromide (C16) by solvothermal technique and solution refluxing. The structure of the PS/OZrP composites was characterized by X‐ray diffraction and high‐resolution electronic microscopy. The thermal behaviors of the composites obtained were investigated by thermogravimetric analysis. The maximum decomposition temperatures (Tmax) of PS/OZrP nanocomposites prepared by solvothermal method increased gradually from 431 to 458°C with the increase of the OZrP loading from 0 to 20 wt %, and the amounts of the charred residue at 600°C (char wt %) had a remarkable increase from 1.6 to 17.1 wt %, respectively. Moreover, the TG results of the nanocomposites prepared by solvothermal method have more obvious enhancement in the thermal stabilities and especially in the amount of charred residue at 600°C (char wt %), which has a double increase from 4.2 to 8.5 wt % at the content of 10 wt % OZrP than by solution refluxing. All results suggested that the solvothermal method is an effective way for the preparation of PS/OZrP nanocomposites with the intercalated nanostructure, which led to the obviously improved thermal stability. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci 122:593–598, 2011  相似文献   

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