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1.
To investigate the effects of two types of clay, namely, Na‐montmorillonite (Na‐MMT) and organic‐montmorillonite (OMMT), on poly(lactic acid) (PLA)/wood flour (WF) composites, some physical and mechanical properties including the water sorption, thickness swelling, flexural modulus of rupture (MOR), and modulus of elasticity (MOE) of PLA/WF composites at different WF contents of 0, 20, 40, and 60 wt% were tested in this study. The results showed that: (1) the 24 h water uptake and thickness swelling increased and the flexural MOR and crystallinity decreased with the increasing WF content, whereas the flexural MOE of the composites increased with WF content up to 40 wt% but decreased sharply at WF content of 60 wt%; (2) the addition of Na‐MMT slightly increased the 24 h water uptake as well as the thickness swelling rate below 40 wt%, whereas OMMT reduced the thickness swelling at higher WF contents (40, 60 wt%) although it showed little effect on 24 h water uptake; (3) both Na‐MMT and OMMT could improve the flexural MOR and MOE of PLA/WF composite at WF contents below 40 wt%, and OMMT resulted in more obvious improvement than Na‐MMT. However, they both showed negative effect at WF content of 60 wt%; (4) XRD and FT‐Raman analysis suggested that clays would be attached more on the surface of the WF rather than diffused in the PLA matrix at a higher WF content (60 wt%); (5) SEM analysis proved that the interfacial adhesion of PLA and WF became poorer at WF content above 40 wt%, whereas it could be improved by OMMT modified. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013  相似文献   

2.
Natural chitosan (CS) at four different additions (10, 20, 30, and 40 phr) and particle size ranges (100–140, 140–180, 180–220, and over 260 mesh) are selected to improve the interface adhesion as well as endow a novel antibacterial function to wood flour/polyvinyl chloride (WF/PVC) composites. In the present study, we investigate the interface self‐reinforcing ability of CS to composites by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), dynamic mechanical analysis (DMA), mechanical testing instrument, and water absorption behavior test (WB). The antibacterial activity is also estimated by the method of membrane covering test (MCT) using Escherichia coli. The results recorded show that adding 30 phr CS with the particle size of over 260 mesh is considered to be perfect selection to prepare the excellent interfacial self‐reinforcing and antibacterial WF/PVC/CS composites. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39854.  相似文献   

3.
In this study, micronized organo‐montmorillonite (OMMT) suspension was prepared with sodium‐montmorillonite (Na‐MMT), didecyl dimethyl ammonium chloride, and dispersant polyethylene glycol 1000 by a ball‐milling process. Then, wood flours (WFs) were impregnated with prepared OMMT suspension at a concentration of 0.5, 1.0, 2.0, or 4.0%. WFs were characterized by X‐ray diffraction and scanning electron microscopy. The hygroscopicity of WF was investigated by a vapor adsorption method. WFs were, respectively, blended with poly (lactic acid) (PLA) to produce WF/PLA composites. Thereafter, physical, mechanical, and thermal properties of the composites were tested. The results showed that a great amount of OMMT attached on the surface of WF, partly penetrating into the microstructure of WF. Owing to the hydrophobicity of OMMT, the vapor adsorption of OMMT‐modified WF decreased. The composite which was produced by WF treated with 0.5% OMMT suspension, showing an increment in the physical, mechanical, and thermal properties. However, OMMT should not be overloaded. Otherwise, the accumulation of OMMT might cause poor interfacial adhesion between WF and PLA matrix. POLYM. COMPOS., 36:731–738, 2015. © 2014 Society of Plastics Engineers  相似文献   

4.
Thermal stability of polyvinyl chloride (PVC) based montmorillonite composites with either sodium montmorillonite (MMT) or alkyl ammonium ion modified montmorillonite (OMMT) were investigated by thermogravimetric analysis. The apparent activation energies associated with the first thermal degradation stage were calculated by the methods of Flynn–Wall–Ozawa and Kissinger in nitrogen atmosphere at several different heating rates. The processing thermal stability of PVC and PVC/MMT(OMMT) composites was also discussed. Increase of mixing torque did not result in a larger intercalation extent of PVC on MMT; instead, it unexpectedly induced discoloration of PVC and then deteriorated the processing stability, especially in the presence of OMMT. The apparent activation energies in the first thermal degradation stage exhibited little difference among PVC, PVC/MMT, and PVC/OMMT composites, and the kinetic compensation effect of Sp* kept a constant value, indicating that the thermal stability and thermal degradation mechanism of PVC were not affected by the presence of either MMT or OMMT, although the processing discoloration of PVC is observed for PVC/OMMT composite. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1521–1526, 2004  相似文献   

5.
Wood polymer nanocomposite (WPNC) was prepared by impregnating Simul (Salmalia malabarica) wood with styrene‐acrylonitrile copolymer (SAN), glycidyl methacrylate(GMA), and a reactive polymerizable surfactant modified montmorillonite (MMT). The physical and mechanical properties of WPNC were investigated by using XRD, tensile tester, SEM, and FTIR. The polymer loading, dimensional stability, water uptake, mechanical property, and thermal stability were found to improve due to inclusion of MMT. SEM micrographs showed the presence of polymer and MMT into cell wall and cell lumen. FTIR analysis confirmed the presence of MMT and SAN in WPNC. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011  相似文献   

6.
Polyurethane/clay nanocomposites have been synthesized using Na+‐montmorillonite (Na+‐MMT)/amphiphilic urethane precursor (APU) chains that have hydrophilic polyethylene oxide (PEO) chains and hydrophobic segments at the same molecules. Nanocomposites were synthesized through two different crosslinking polymerization methods. One is UV curing of melt mixed APU/Na+‐MMT mixtures; the other is coalescence polymerization of APU/Na+‐MMT emulsions. These two kinds of composites had intercalated silicate layers of Na+‐montmorillonite by insertion of PEO chains in APU chains, which was confirmed by X‐ray diffraction measurement and transmission electron microscopy. These composite films also showed improved mechanical properties compared to pristine APU films. Although the two kinds of nanocomposites exhibited the same degree of intercalation and were synthesized based on the same precursor chains, these nanocomposite films had the different mechanical properties. Nanocomposites synthesized using APU/Na+‐MMT emulsions, having microphase‐separated structure, had greater tensile strength than those prepared with melt‐mixed APU/Na+‐MMT mixtures. Location of intercalated Na+‐MMT by PEO chains at the oil–water interface also could be confirmed by rheological behavior of the APU/Na+‐MMT/water mixture. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 3130–3136, 2003  相似文献   

7.
Montmorillonite (MMT) of which the surface was modified with a block copolymer with crosslinkable units was incorporated into methacrylate‐based composites as nanofiller to improve dimensional and mechanical properties. A bifunctional block copolymer containing 2‐isocyanato ethyl methacrylate in one block and poly(vinyl pyridine) units in the other block was prepared as the block copolymeric surface modifier for MMT through controlled/“living” radical polymerization technique. Application of the modified MMT in 2,2‐bis[4‐(2‐hydroxy‐3‐methacryloyl‐oxy)phenyl]propane (bis‐GMA) based composites showed that polymerization shrinkages of the composites decreased as the content of modified MMT increased. Compressive and flexural strengths of the composites were also improved in the presence of the modified MMT, which demonstrate the beneficial effect of the modified MMT as a nanofiller and IEM as a cocrosslinkable unit. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013  相似文献   

8.
This work focuses on the influence of weathering factors—UV radiation, humidity, and temperature on the structure and morphology of poly(vinyl chloride)/montmorillonite (PVC/MMT) nanocomposites obtained by melt blending. It has been observed that organically modified MMT (OMMT) deteriorates the weathering resistance, the thermal behavior, as well as the long‐term stability of PVC. Decomposition of the organic modifier of MMT causes substantial color changes in the PVC nanocomposites as it facilitates the dehydrochlorination process of the polymer. However, the nonmodified MMT provides some stabilization during PVC weathering. The nanocomposites after annealing are characterized by higher glass transition temperature. The increase in heat capacity step (Δcp) during glass transition suggests that in the PVC composites with nonmodified MMT stronger molecular interactions between the polymer and clay platelets occur than in PVC/OMMT nanocomposites. The scanning electron microscopy images on the surface and the cross section show that thermal aging and weathering proceed by different mechanisms. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42090.  相似文献   

9.
In this research, wood flour (WF) was modified using sodium–montmorillonite (Na‐MMT) at four different concentrations (0.5, 1.0, 2.0, and 4.0 wt%, respectively) and didecyl dimethyl ammonium chloride (DDAC) in a two‐step process to form organo‐montmorillonite (OMMT) inside the WF or attached to the WF surface. The thus‐modified WF was then mixed with poly(lactic acid) (PLA) to produce WF/PLA composites. The thermal stability of these composites with respect to their resistance against both thermal deformation and thermal decomposition was characterized by stress relaxation, differential scanning calorimetry (DSC), and thermogravimetric (TG) analysis. Besides, the activation energies for thermal decomposition of the composites were calculated. The results showed the following: (1) The modification of WF by OMMT improved the resistance against thermal deformation of the composites at appropriate OMMT loadings (lower than 1 wt% in this study). However, after introducing excessive OMMT, the enhancements in thermal stability diminished. Composite containing WF modified by 0.5 wt% of OMMT showed the optimal thermal deformation stability in this study, reflected in the highest values of thermal properties such as the glass transition temperature, melting temperature, crystallization temperature, and slowest stress relaxation rate. (2) OMMT showed a negative effect on the resistance against thermal decomposition. Namely, OMMT accelerated the thermal decomposition of the composites, probably by the easier degradation of the organic surfactant used for the WF modification. However, this behavior might be favorable for achieving fire retardancy. POLYM. COMPOS., 37:1971–1977, 2016. © 2015 Society of Plastics Engineers  相似文献   

10.
On the basis of the fusion behavior of poly(vinyl chloride) (PVC), the influence of compounding route on the properties of PVC/(layered silicate) nanocomposites was studied. Four different compounding addition sequences were examined during the melt compounding of PVC with montmorillonite (MMT) clay, including (a) a direct dry mixing of PVC and nanoclay, (b) an addition of nanoclay at compaction, (c) an addition of nanoclay at the onset of fusion, and (d) an addition of nanoclay at equilibrium torque. Both unmodified sodium montmorillonite (Na+‐MMT) and organically modified montmorillonite (Org.‐MMT) clays were used, and the effect of the addition sequence of the clay during compounding on its dispersion in the matrix was evaluated by X‐ray diffraction and transmission electron miscroscopy. The surface color change, dynamic mechanical analysis, and flexural and tensile properties of PVC/clay nanocomposites were also studied. The experimental results indicated that both the extent of property improvement and the dispersion of nanoparticles in PVC/(layered silicate) nanocomposites are strongly influenced by the degree of gelation achieved in PVC compounds during processing. The addition of nanoclay to PVC must be accomplished at the onset of fusion, when PVC particles are reduced in size, in order to produce nanocomposites with better nanodispersion and enhanced mechanical properties. Overall, rigid PVC nanocomposites with unmodified clay (Na+‐MMT) were more thermally stable and exhibited better mechanical properties than their counterparts with organically modified clay (Org.‐MMT). J. VINYL ADDIT. TECHNOL., 2009. © 2009 Society of Plastics Engineers  相似文献   

11.
Polypropylene (PP)/montmorillonite (MMT) nanocomposites were prepared by compounding maleic anhydride‐g‐polypropylene (MAPP) with MMT modified with α,ω‐diaminododecane. Structural characterization confirmed the formation of characteristic amide linkages and the intercalation of MAPP between the silicate layers. In particular, X‐ray diffraction patterns of the modified clay and MAPP/MMT composites showed 001 basal spacing enlargement as much as 1.49 nm. Thermogravimetric analysis revealed that the thermal decomposition of the composite took place at a slightly higher temperature than that of MAPP. The heat of fusion of the MAPP phase decreased, indicating that the crystallization of MAPP was suppressed by the clay layers. PP/MAPP/MMT composites showed a 20–35% higher tensile modulus and tensile strength compared to those corresponding to PP/MAPP. However, the elongation at break decreased drastically, even when the content of MMT was as low as 1.25–5 wt %. The relatively short chain length and loop structure of MAPP bound to the clay layers made the penetration of MAPP molecules into the PP homopolymer phase implausible and is thought to be responsible for the decreased elongation at break. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 95: 307–311, 2005  相似文献   

12.
Polypropylene (PP)/montmorillonite (MMT) nanocomposites were prepared by the esterification of propylene‐g‐maleic anhydride (MAPP) with MMT modified with α,ω‐hydroxyamines. The structural characterization confirmed the formation of ester linkages and the interaction between the silicate layers. In particular, X‐ray diffraction patterns of the modified clays and MAPP/MMT composites showed 001 basal spacing enlargement as great as 0.14–0.62 nm according to the type of α,ω‐hydroxyamine. Thermal characterization by thermogravimetric analysis for the composites revealed increased onset temperatures of thermal decomposition. The melting peak temperature decreased, and the crystallization peak temperature increased; this indicated that MMT retarded the crystallization of MAPP. Compounding PP with MAPP/MMT composites enhanced the tensile modulus and tensile strength of PP. However, the elongation at break decreased drastically even when the MMT content was as low as 0.4–2.0 wt %. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 1229–1234, 2005  相似文献   

13.
Polyacrylamide/sodium alginate modified montmorillonite (PAM/SA‐MMT) superabsorbent composites were synthesized by free‐radical polymerization under normal atmospheric conditions. They were characterized by X‐ray diffraction, scanning electron microscopy, and Fourier transform infrared spectroscopy (FTIR). Their water absorbency and methylene blue (MB) adsorption behaviors were studied. Compared with PAM/MMT composites, PAM/SA‐MMT composites demonstrated greater water absorbency (863 g g?1 in distilled water and 101 g g?1 in 0.9 wt % NaCl solution) and higher adsorption capacity of 2639 mg g?1 for MB. The adsorption behaviors of the composites showed that the isotherms and adsorption kinetics were in good agreement with the Langmuir equation and pseudo‐second‐order equation, respectively. FTIR analysis suggested that the MB adsorption of PAM/SA‐MMT composites via a mechanism combined electrostatic, H‐bonding and hydrophobic interaction. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2014 , 131, 40013.  相似文献   

14.
Natural rubber nanocomposites were produced by melt‐mixing of natural rubber with organically modified silicates. For comparison, a pristine‐layered silicate and a nonlayered version [English Indian clay (EIC)] were also included in the study. The layered silicate used was sodium bentonite (BNT) and organoclays used were octadecylamine‐ modified montmorillonite (MMT‐ODA) and methyltallow bis‐2‐hydroxyethyl ammonium‐modified montmorillonite (MMT‐ TMDA). Accelerated sulfur system was used for the vulcanization of the nanocomposites. The dispersion of these silicates was studied by X‐ray diffraction and transmission electron microscopy. The organoclay‐incorporated composites exhibited faster curing and improved mechanical properties. The improvement in the mechanical properties of the composites followed the order MMT‐ODA > MMT‐TMDA > EIC > BNT. The property improvement was attributed to the intercalation/exfoliation of the organically modified silicates because of their high initial interlayer distance. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 2537–2543, 2006  相似文献   

15.
Composites based on PVC were compounded with 5% of montmorillonite and 10% of PMMA. Two types of reinforcement were studied, which included a purified sodium montmorillonite and a montmorillonite organically modified with an alkylammonium chloride. The composites were compounded with a Gelimat type thermokinetic mixer and were ejected at a maximum temperature of 180°C. The organically modified montmorillonite discolored the PVC, result which was interpreted as a sign of chemical degradation caused by the alkylammonium modifier. The composite made with 5% of purified montmorillonite and 10 of % PMMA displayed the best overall properties. The most important improvement was obtained on flexural strain at break (0.097–0.175 mm/mm) and maximum flexural strength (62–76 MPa). The HDT increased by up to 8°C. Dynamic mechanical analysis showed that 10% of PMMA in PVC moved the tan δ peak to temperatures 5–6°C higher. The PMMA was completely miscible in PVC and played an important role in the montmorillonite dispersion, as observed by XRD and SEM analysis. It also contributed to the overall increase in properties of PVC/PMMA/montmorillonite composites. J. VINYL ADDIT. TECHNOL., 13:91–97, 2007. © 2007 Society of Plastics Engineers.  相似文献   

16.
The effects of various additives on the performance of 2,2′‐bis[4‐(methacryloxy‐2‐hydroxy‐propoxy)‐phenyl]‐propane (Bis‐GMA)/barium glass powder (Ba) composites were examined. Bis‐GMA/Ba composites were manufactured by curing with visible light to measure various mechanical properties. The diametral tensile strengths (DTS) of Bis‐GMA/Ba composites were the primary focus of this investigation. The main additives used were trimethylolpropyltrimethacrylate (TMPT), 1,4‐bis‐(tri‐methoxysilylethyl) benzene (BTB), and cationic styryl silane. These additives were applied as both integral blends and aqueous pretreatments. Besides the DTS, Vickers hardness of cured matrix resins and the viscosity of composite pastes were measured to study the properties of the matrix resins and the processibility of the composites, respectively. Integral blends showed similar processibility to aqueous pretreatments. The addition of TMPT to the matrix resins increased Vickers hardness of integral blend systems as a result of its trimethacrylate functional group. BTB was useful in increasing the wet DTS of Bis‐GMA/silane–treated Ba composites. STS was effective in improving the performance of Bis‐GMA/Ba composites in the cases of both the integral blends and aqueous pretreatments. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 76: 1085–1092, 2000  相似文献   

17.
采用熔融插层法制备了聚氯乙烯/蒙脱土(PVC/MMT)插层产物,再将该产物与环氧化天然橡胶(ENR)在密炼机中进行熔融共混制备ENR/PVC/MMT共混型热塑性弹性体(TPV),研究了不同改性MMT对共混物力学性能、热稳定性以及动态力学性能的影响。结果表明:二甲基双十八烷基铵改性蒙脱土(MMT-2C18)能显著提高ENR/PVC共混型TPV的拉伸强度,无机MMT能显著提高ENR/PVC的断裂伸长率,十八烷基铵改性蒙脱土(MMT-C18)会降低TPV的拉伸强度和断裂伸长率;有机改性MMT会促进TPV中PVC的降解,使得复合材料的热稳定性降低;动态热力学分析显示,MMT可使复合材料的储能模量增加,其中有机改性MMT使材料的损耗因数(tanδ)曲线峰强降低,峰宽变宽。  相似文献   

18.
In this study, montmorillonite (MMT)/poly(?‐caprolactone)‐based polyurethane cationomer (MMT/PCL‐PUC) nanocomposites were prepared and their mechanical properties, thermal stability, and biodegradability were investigated. PCL‐PUC has 3 mol % of quaternary ammonium groups in the main chain. The MMT was successfully exfoliated and well dispersed in the PCL‐PUC matrix for up to 7 wt % of MMT. The 3 mol % of quaternary ammonium groups facilitated exfoliation of MMT. The 1 wt % MMT/PCL‐PUC nanocomposites showed enhanced tensile properties relative to the pure PCL‐PU. As the MMT content increased in the MMT/PCL‐PUC nanocomposites, the degree of microphase separation of PCL‐PUC decreased because of the strong interactions between the PCL‐PUC chains and the exfoliated MMT layers. This resulted in an increase in the Young's modulus and a decrease in the elongation at break and maximum stress of the MMT/PCL‐PUC nanocomposites. Biodegradability of the MMT/PCL‐PUC nanocomposites was dramatically increased with increasing content of MMT, likely because of the less phase‐separated morphology of MMT/PCL‐PUC. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008  相似文献   

19.
Two types of modified montmorillonite (MMT) were achieved using octadecylamine as the modifying agent by the methods of dry process and wet route. Polypropylene (PP)/MMT nanocomposites were prepared using the melt mixing technique and employing maleic anhydride‐grafted polypropylene (PP‐MA) as the compatibilizer. The modification of montmorillonite was characterized by fourier transform infrared spectroscopy (FTIR), X‐ray diffraction (XRD), and scanning electron microscope (SEM). The effect of MMT modification and PP‐MA on the microstructure and properties of PP/MMT nanocomposites was investigated by SEM, differential scanning calorimeter (DSC), thermogravimetric analysis (TGA), dynamic mechanical analysis (DMA), and polarizing microscopy. The results show that organic montmorillonite modified by wet process (WOMMT) has a large d‐spacing increment; whereas montmorillonite modified by dry process (DOMMT) shows little d‐spacing increment. Furthermore, the mechanical properties of composites incorporating WOMMT are better than that containing DOMMT. As a third component, the addition of PP‐MA benefits the formation of exfoliated structure and the dispersion of MMT in PP matrix, and hence, enhances the physical properties of the nanocomposite. With the presence of PP‐MA, the highly dispersed MMT increases the number of spherulite crystals, enhances the melting enthalpy, improves the thermal stability, and induces the desired tiny crazes more effectively. MMT increases the storage modulus (E′) and glass‐transition temperature (Tg) of PP because of the stiffness of MMT layers, but PP‐MA decreases them owing to its high melt flow index, both of which were in favor of improving the physical properties. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 3952–3960, 2013  相似文献   

20.
The gas‐barrier properties of elastomer are of particular importance, especially for airtight applications. Poly(di‐isoamyl itaconate‐co‐isoprene) (PDII) is a newly invented and respectable biobased elastomer, but the barrier properties of PDII and its composites with carbon black and silica are not satisfying at all. Because there are abundant ester groups in PDII macromolecules and these groups can contribute to the homogeneous dispersion of layer silicates, we applied layered silicates, including montmorillonite (MMT) and rectorite (REC), into the PDII matrix to improve the air impermeability. MMT/PDII and REC/PDII composites were prepared by a cocoagulation method, and the air impermeability of the PDII elastomer was highly improved. The smallest gas permeability index reached 1.7 × 10?17 m2 Pa?1 s?1 at an REC content of 80 phr; this implied a reduction of 85.5%. A comparison of the two types of silicate/PDII composites showed that the MMT/PDII composites had better properties at low filler contents, whereas the REC/PDII composites had better mechanical and gas‐barrier properties at high filler contents. Other structures and properties of the composites were investigated by X‐ray diffraction, transmission electron microscopy, and dynamic mechanical rheology. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40682.  相似文献   

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