Compatibilization of the partially miscible poly(vinylidene fluoride) (PVDF)/poly(styrene-co-acrylonitrile) (SAN) pair by a third homopolymer, i.e., poly(methyl methacrylate) (PMMA), was investigated in relation to
cross section morphology, crystallization behaviors and hydrophilicity of the polyblends. Scanning electron microscopy showed
a more regular and homogeneous morphology when more than 15 wt.% PMMA was incorporated. The samples presented only α phase
regardless of PMMA content in the blend. As the PMMA content increased in the blends, the interactions between each component
were enhanced, and the crystallization of PVDF was limited, leading to a decreasing of the crystallinity and the crystallite
thickness. Besides, the hydrophilicity of PVDF was further improved by PMMA addition. The sample containing 15 wt.% PMMA showed
a more hydrophilic property due to the more polar part of surface tension induced by PMMA addition. Observed from the cross
section of the blends, the miscibility of partially miscible PVDF/SAN blends were efficiently improved by PMMA incorporation. 相似文献
Poly(vinylidene fluoride)/multiwalled carbon nanotube (PVDF/MWCNT) composites were prepared by the method of solution blending. The non-isothermal crystallization of PVDF and its composites was investigated by differential scanning calorimetry (DSC). The results showed that the crystallization peaks shifted to lower temperature and the exothermic trace became wider when cooling rate increased for PVDF and its composites. The MWCNTs caused an increase in crystallization temperature and initial crystallization temperature. In addition, the Jeziorny and Mo methods were used to analyze the non-isothermal crystallization kinetics. The results showed that the crystallization rate rose with an increase in cooling rate, however, the MWCNTs decreased the crystallization rates of PVDF. 相似文献
In this paper, the influence of rubber particle size on the phase interface in dynamically vulcanized poly(vinylidene fluoride)/silicone rubber (PVDF/SR) blends without any modifier is discussed through the studies of specific surface of crosslinked SR particles, crystallization behavior and crystal morphology of the PVDF phase, interfacial crystallization, melt rheological behavior and mechanical properties of blends. A series of decreased average particle size was successfully obtained by control of rotor rate. It was found that properly high rotor rate helped to achieve a reduced particle size and a narrowing size distribution. The reduced SR particle size enlarged the PVDF/SR interface which has a positive effect on the interfacial crystallization and the melt rheological behavior. At high SR content, the negative effect of the poor interface interactions played the dominate role on determining the mechanical properties. However, the blend exhibited a unique stiffness-toughness balance at the PVDF/SR = 90/10. We hope that the present study could help to lay a scientific foundation for further design of a useful PVDF/SR blend with promoted properties to partly replace the high-cost synthetic fluorosilicone materials. 相似文献
Carbon nanotube (CNT), graphene nanoplatelet (GnP) and organo-montmorillonite (15 A) individually and simultaneously served as reinforcing fillers to prepare poly (vinylidene fluoride) (PVDF)/polycarbonate (PC) blend-based multicomponent nanocomposites. Scanning electron microscopy and transmission electron microscopy results confirmed the selective localization of individual and hybrid fillers within the PC domains. Some 15 A was located at the interface of PVDF/PC phases to modify the blend morphology. Addition of CNT led to the development of a quasi co-continuous PVDF-PC morphology. Differential scanning calorimetry results showed that 15 A, not CNT/GnP, facilitated PVDF crystallization in the composites. Among the fillers, 15 A alone induced β-form PVDF crystals, as revealed by the X-ray diffraction results, and consequently caused the complex crystallization and melting of PVDF. The rigidity (Young's and flexural moduli) of the PVDF/PC blend increased after the formation of various blend-based nanocomposites. The hybrid filler of CNT/15 A increased the Young's modulus by approximately 90% compared with that of the blend. Rheological property measurements confirmed the formation of a pseudo-network structure in the composites. Adding CNT increased the complex viscosity of the samples to a higher extent than did adding GnP, and the viscosity further increased with the co-existence of carbon nanofiller(s) and 15 A. 相似文献
The crystallization process of poly(ethylene oxide) (PEO)/poly(methyl methacrylate) (PMMA)and PEO/poly(vinyl acetate) (PVAc) blends has been characterized by Fourier Transform Infrared(FTIR) spectra in conjunction with Differential Scanning Calorimeter (DSC) measurements. Thecrystallinity of PEO varies consistently with PEO content in PEO/PVAc blends and the PEO/PMMAblends containing 50 wt% or less PMMA. For the PEO/PMMA blends containing 60 wt% ormore PMMA, the crystallinity of PEO decreases more than PEO content but develops with crystal-lization time. These results can be explained in terms of difference between the crystallization tem-perature (T_c) and glass transition temperature (T_g) of the blends as a function of content of amorphouscomponent. 相似文献
Poly (styrene-co-acrylonitrile) (SAN) is a hydrophilic non-crystalline copolymer, which is initially used in this paper to improve the hydrophilicity
of poly (vinylidene fluoride) (PVDF). Investigation of the crystallization behavior of PVDF/SAN blends showed that the samples
presented only α phase regardless of SAN content as cooling from the melt. A double-melting phenomenon was related to the
perfection or crystal size of PVDF crystals. As the SAN content is increasing, crystallization of PVDF was limited, leading
to a decreased crystallinity and lamellar growth. Besides, the hydrophilicity of PVDF was improved by blending with SAN. The
sample containing 70 wt.% SAN performed a similar surface property of the neat SAN owing to the besieging of the PVDF phase
by SAN. Observed from the cross section of the blends, PVDF/SAN blends were partially miscible with less than 50 wt.% SAN
addition. As the SAN content was more than 50 wt.%, the crystalline PVDF particles clearly dispersed in the amorphous matrix. 相似文献
Before polymerization, the introduction of double bonds onto the surface of the TiO2 particles was achieved by the treatment of the TiO2 particles with the silane-coupling agent. Via in-situ emulsion polymerization, the poly(methyl methacrylate) (PMMA)/titanium oxide (TiO2) composite particles were prepared by graft polymerization of MMA from the surface of the modified TiO2 particles. The structure of the obtained PMMA/TiO2 composite particles was characterized using fourier transform infrared spectra (FT-IR), thermo-gravimetric analysis (TGA), differential scanning calorimetry (DSC) and size excluding chromatography (SEC). The morphology of the obtained PMMA/TiO2 composite particles was observed by transmission electron microscope (TEM). The results of FT-IR and TGA measurements show that PMMA is successfully grafted from the surface of the TiO2 particles and that the percentage of grafting and the grafting efficiency can reach 208.3% and 96.6%, respectively. At the same time, the TGA and DSC measurements indicate an enhancement of thermal stability. TEM images demonstrate a better dispersion of the TiO2 particles in the composite latex. In addition, UV-visible absorption measurements show that the PMMA/TiO2 composite particles can absorb over 95% UV light at 210–400 nm wavelength. 相似文献
The oriented crystallization of poly(vinylidene fluoride) (PVDF) in stretched films of a PVDF/nylon 11 blend was investigated. At low crystallization temperature the c‐axis of the PVDF α‐form was oriented to the orientation axis of the nylon 11 matrix, but c‐axis orientation gradually changed to a‐axis orientation upon increasing the crystallization temperature. Under all crystallization conditions studied, considerable amounts of PVDF in its β‐form with c‐axis orientation were produced as well.
Phase morphology of a stretched film of PVDF/nylon 11 blend observed with confocal laser scanning microscopy. 相似文献
Direct insertion probe pyrolysis mass spectrometry (DIP-MS) analyses of polycarbonate/poly(methyl methacrylate)/poly(vinyl acetate), (PC/PMMA/PVAc), ternary blends have been performed. The PC/PMMA/PVAc ternary blends were obtained by coalescing from their common γ-cyclodextrin-inclusion compounds (CD-ICs), through the removal of the γ-CD host (coalesced blend), and by a co-precipitation method (physical blend). The coalesced ternary blend showed different thermal behaviors compared to the co-precipitated physical blend. The stability of PC chains decreased due to the reactions of CH3COOH formed by deacetylation of PVAc above 300 °C, for both coalesced and physical blends. This process was more effective for the physical blend most likely due to the enhanced diffusion of CH3COOH into the amorphous PC domains, where it can further react producing low molecular weight PC fragments bearing methyl carbonate chain ends. The decrease in thermal stability of PC chains was less significant for the coalesced ternary blend indicating that the diffusion of CH3COOH was either somewhat limited or competed with intermolecular reactions between PMMA and PC and between PMMA and PVAc, which were detected and were associated with their close proximity in the intimately mixed coalesced PC/PMMA/PVAc ternary blend. 相似文献
A new plasticized dual-phase polymer electrolyte (DPE) with enhanced phase compatibility based on Poly(MMA-g-PVC)/PMMA blends has been studied. For the DPE, PMMA is selectively impregnated with the lithium salt solution forming an ion-conducting network, while Poly(MMA-g-PVC) produces good mechanical strength. Their chemical characters, thermal behavior, morphology, ionic conductivity and interfacial compatibility with lithium metal electrode were characterized by using of infrared spectroscopy (IR), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), optical microscopic images, alternating current impedance (AC impedance) and linear sweep voltammetry (LSV), respectively. The ionic conductivity of DPE increases with the ratio of PMMA/Poly(MMA-g-PVC) (by weight), and the absorbed liquid electrolyte in the polymer blends plays the first important way in this behavior. Room-temperature ionic conductivity of the order of 10−3 S cm−1 has been achieved for DPE, in addition, the DPE also shows good compatibility with Li electrodes and sufficient electrochemical stability for safe operation in Li batteries. 相似文献
Poly(L-lactic acid)(PLLA)-based composites exhibit wide applications in many fields.However,most of hydrophilic fillers usually accelerate the hydrolytic degradation of PLLA,which is unfavorable for the prolonging of the service life of the articles.In this work,a small quantity of poly(methyl methacrylate)(PMMA)(2 wt%-10 wt%)was incorporated into the PLLA/carbon nanotubes(CNTs)composites.The effects of PMMA content on the dispersion of CNTs as well as the microstructure and hydrolytic degradation behaviors of the composites were systematically investigated.The results showed that PMMA promoted the dispersion of CNTs in the composites.Amorphous PLLA was obtained in all the composites.Largely enhanced hydrolytic degradation resistance was achieved by incorporating PMMA,especially at relatively high PMMA content.Incorporating 10 wt%PMMA led to a dramatic decrease in the hydrolytic degradation rate from 0.19%/h of the PLLA/CNT composite sample to 0.059%/h of the PLLA/PMMA-10/CNT composite sample.The microstructure evolution of the composites was also detected,and the results showed that no crystallization occurred in the PLLA matrix.Further results based on the interfacial tension calculation showed that the enhanced hydrolytic degradation resistance of the PLLA matrix was mainly attributed to the relatively strong interfacial affinity between PMMA and CNTs,which prevented the occurrence of hydrolytic degradation at the interface between PLLA and CNTs.This work provides an alternative method for tailoring the hydrolytic degradation ability of the PLLA-based composites. 相似文献
Summary: Thermal properties of nanocomposites prepared of poly(L-lactide) (PLLA) and CaCO3 applying differential scanning (DSC) calorimetry and thermogravimetry (TG) were studied. Nanocomposites were prepared by extrusion process at 170 °C. DSC measurements show that CaCO3 has no influence on glass transition and melting point of PLLA but lowers its cold crystallization temperature. There is no difference in glass transition temperature of PLLA before and after extrusion. High temperature thermal stability of the PLLA in the composites is poorer than neat PLLA. Kinetic parameters also indicate greater reactivity of the system upon CaCO3 addition. 相似文献
Pristine multi-walled carbon nanotubes (MWNTs) were incorporated into poly(vinylidene fluoride) (PVDF), poly(methyl methacrylate) (PMMA), and PVDF/PMMA blends to achieve binary and ternary nanocomposites. MWNTs were more compatible with the PVDF matrix than with the PMMA-containing matrices. MWNT addition did not alter the development of α-form PVDF crystals in the binary/ternary composites. Nucleation and overall isothermal crystallization of PVDF were enhanced by the presence of MWNTs, and enhancements were optimal in the PVDF/MWNT binary composites. Avrami analysis revealed that addition of MWNTs led to more extensive athermal-type nucleation of PVDF, and that PMMA slightly decreased the crystal growth dimension of PVDF. The equilibrium melting temperature (Tm°) of PVDF increased in the binary composites but remained nearly constant in the ternary system. Thermal stability was enhanced in the binary/ternary composites, and enhancements were more evident in the air environment than in nitrogen. Rheological property measurements revealed that the intensely entangled chains of high-molecular weight PVDF dominated the rheological response of PVDF-included samples in the melt state. A (pseudo)network structure was developed in each of the PVDF-included samples as well as in the 1 phr MWNT-added PMMA/MWNT composite. The storage moduli of the PVDF, PMMA, and PVDF/PMMA:1/1 blend increased to 37%, 22% and 34%, respectively, at 40 °C after addition of 1 phr MWNT. 相似文献
The glass-transition temperature and non-isothermal crystallization of poly(trimethylene terephthalate)/poly(ethylene 2,6-naphthalate) (PTT/PEN) blends were investigated by using differential scanning calorimeter (DSC). The results suggested that the binary blends showed different crystallization and melting behaviors due to their different component of PTT and PEN. All of the samples exhibited a single glass-transition temperature, indicating that the component PTT and PEN were miscible in amorphous phase. The value of Tg predicted well by Gordon-Taylor equation decreased gradually with increasing of PTT content. The commonly used Avrami equation modified by Jeziorny, Ozawa theory and the method developed by Mo were used, respectively, to fit the primary stage of non-isothermal crystallization. The kinetic parameters suggested that the PTT content improved the crystallization of PEN in the binary blend. The crystallization growth dimension, crystallization rate and the degree of crystallinity of the blends were increased with the increasing content of PTT. The effective activation energy calculated by the advanced iso-conversional method developed by Vyazovkin also concluded that the value of Ea depended not only on the system but also on temperature, that is, the binary blend with more PTT component had higher crystallization ability and the crystallization ability is increased with increasing temperature. The kinetic parameters U* and Kg were also determined, respectively, by the Hoffman-Lauritzen theory. 相似文献