Understanding of intermolecular interaction in PVDF/PTW blends: Crystallization behavior,thermal, and dynamic mechanical properties

Poly(vinylidene fluoride) (PVDF)/ poly(ethylene–butylacrylate–glycidyl methacrylate) (PTW) blends were directly prepared by melt blending and the interaction and properties of PVDF/PTW blends were explored systematically. The crystallization behavior, thermal stability, dynamic mechanical property, and morphological features of PVDF/PTW blends with different ratios have been studied by XRD, attenuated total reflection Fourier transform infrared spectroscopy, differential scanning calorimeter analysis (DSC), thermal gravimetric analysis (TGA), dynamic mechanical analysis, and polarized optical microscopy (POM). The results showed that the crystalline structure of neat PVDF was dominantly α‐phase crystalline and the incorporation of PTW had no effect on the crystalline structure of PVDF in the PVDF/PTW blends. And T_g of PVDF in PVDF/PTW blends shifted to higher temperature compared with that of neat PVDF, indicating the weak interaction between PVDF and PTW, which was corresponding to DSC and TGA results. An increase in the coarseness and ring‐band spacing observed from POM further substantiated the weak interaction between PVDF and PTW. This work provided a way for preparing improved properties of PVDF/PTW blends for the coating material. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43908.     

Crystallization behavior and hydrophilicity of poly(vinylidene fluoride)/poly(methyl methacrylate)/poly(vinyl pyrrolidone) ternary blends

Ternary blends composed of matrix polymer poly(vinylidene fluoride) (PVDF) with different proportions of poly(methyl methacrylate) (PMMA)/poly(vinyl pyrrolidone) (PVP) blends were prepared by melt mixing. The miscibility, crystallization behavior, mechanical properties and hydrophilicity of the ternary blends have been investigated. The high compatibility of PVDF/PMMA/PVP ternary blends is induced by strong interactions between the carbonyl groups of the PMMA/PVP blend and the CF₂ or CH₂ group of PVDF. According to the Fourier transform infrared and wide‐angle X‐ray difffraction analyses, the introduction of PMMA does not change the crystalline state (i.e. α phase) of PVDF. By contrast, the addition of PVP in the blends favors the transformation of the crystalline state of PVDF from non‐polar α to polar β phase. Moreover, the crystallinity of the PVDF/PMMA/PVP ternary blends also decreases compared with neat PVDF. Through mechanical analysis, the elongation at break of the blends significantly increases to more than six times that of neat PVDF. This confirms that the addition of the PMMA/PVP blend enhances the toughness of PVDF. Besides, the hydrophilicity of PVDF is remarkably improved by blending with PMMA/PVP; in particular when the content of PVP reaches 30 wt%, the water contact angle displays its lowest value which decreased from 91.4° to 51.0°. Copyright © 2011 Society of Chemical Industry     

Investigation of the crystalline structure of PVDF in PVDF/PMMA/graphene polymer blend nanocomposites

In this work, we report the preparation of poly(vinylidene fluoride)/poly methylmethacrylate (PVDF/PMMA)/graphene polymer blend nanocomposites via synthesis of PMMA/graphene as a masterbatch through in situ polymerization. The PMMA/graphene masterbatch compounded with PVDF by solution mixing in different ratios. The compounding was followed by solution casting to form polymer blend nanocomposites. Solution cast films were subjected to thermal treatments at three different temperatures. The crystalline structure of thermally treated samples was studied with X‐ray diffraction spectroscopy and Differential Scanning Calorimetric (DSC) analysis. Results indicated PMMA chains persuade the β crystalline form in PVDF but cannot stabilize them in elevated temperature; however, graphene sheets due to restricting effect on TT conformation chains are able to stabilize them. DSC data revealed the graphene sheets can increase the crystallinity of PVDF and also act as nucleating agents. Transmission Electron Microscopy demonstrated coexistence of the different stacking orders of graphene sheets in both masterbatch and polymer blend nanocomposite. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers     

PVDF/PMMA复合材料的微观结构及形态

采用非晶态聚甲基丙烯酸甲酯（PMMA）与结晶型聚偏氟乙烯（PVDF）熔融共混．制备了PVDF／PMMA复合材料。利用Hilderbrand的溶解参数原则、差示扫描量热法（DSC）和微分热重法（DTG）分析了PVDFfPMMA共混物的相容性和热性能,并用X射线衍射仪和扫描电子显微镜研究了共混片材的微观结构与形态。结果表明,PMMA与PVDF具有良好的相容性,PMMA的加入降低了PVDF的结晶能力和熔融温度;随着PMMA的含量增加,PVDF的分解温度降低;PVDF的结晶度降低,球晶尺寸增大。另外,PMMA的引入改变了PVDF的结晶结构,导致了β相形成。     

Evidence for a crystal-amorphous interphase in PVDF and PVDF/PMMA blends

Dielectric relaxation studies and absolute small-angle X-ray investigations give evidence that amorphous interlamellar regions in partially crystalline PVDF/PMMA blends consist of two phases: a pure amorphous PVDF phase and a homogeneously mixed PVDF/PMMA phase. The local phase separation which occurs, despite favourable interactions between PMMA and PVDF, is attributed to a PVDF crystal-amorphous interphase which rejects PMMA segments. The thickness of this interphase is found to be of the order of 2.5 nm.     

Poly(vinylidene fluoride)–acrylic rubber partially miscible blends: Phase behavior and its effects on the mechanical properties

A phase diagram of poly(vinylidene fluoride) (PVDF) and acrylic rubber (ACM) was plotted, and the effects of the extent of miscibility on the mechanical properties of the polymer blends were examined. A compressible, regular solution model was used to forecast the phase diagram of this blend. The model prediction, the lower critical solution temperature (LCST) over the upper critical solution temperature (UCST), was done qualitatively according to the experimentally determined phase diagram by differential scanning calorimetry (DSC), optical microscopy, and rheological analysis. These experimental methods showed that this system was miscible in ACM‐rich blends (>50% ACM) and partially miscible in PVDF‐rich blends. A wide‐angle X‐ray diffraction study revealed that PVDF/ACM blends such as neat PVDF had a characteristic α‐crystalline peak. The partially miscible blends displayed up to 350% elongation at break; this was a significant increment of this parameter compared to that of neat PVDF(20%). However, the miscible blends showed elongation of up to 1000% [again, a remarkable increase compared to chemically crosslinked ACM (220%)] and displayed excellent mechanical properties and tensile strength and a large elongation at break. For the miscible and partially miscible blends, two different mechanisms were responsible for this improvement in the mechanical properties. It was suggested that in the partially miscible blends, the rubbery depletion layer between the spherulite and the conventional rubber cavitations mechanism were responsible for the increase in the elongation at break, whereas for the miscible blends, the PVDF spherulite acted as a crosslinking junction. The stretched part of the tensile samples in the partially miscible blends showed characteristic β‐crystalline peaks in the Fourier transform infrared spectra, whereas that in the miscible blends showed α‐crystalline peaks. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 1247‐1258, 2013     

Studies on morphology,mechanical, thermal,and dynamic mechanical behavior of extrusion blended polypropylene and thermotropic liquid crystalline polymer in presence of compatibilizer

Polypropylene was melt blended in a single screw extruder with thermo tropic Vectra B‐950 liquid crystalline polymer (copolyester amide) in different proportions in presence of 2% of EAA, ethylene‐acrylic acid copolymer (based on PP) as a compatibilizer. The mechanical properties of such compatibilized blends were evaluated and compared in respect of their Young's Modulii, Ultimate tensile strength, percent elongation at break, and toughness to those of Pure PP. The Morphology was studied by using a polarizing light microscope (PLM) and Scanning electron microscope (SEM). The Thermal characterization of these blends were carried out by differential scanning calorimeter (DSC).The mechanical properties under dynamic conditions of such compatibilized blends and pure PP were studied by dynamic mechanical analyzer (DMA). Mechanical analysis (Tensile properties) of the compatibilized blends displayed improvements in Modulii and ultimate tensile strength (UTS) of PP matrix with the incorporation of 2–10% of LCP incorporation. The development of fine fibrillar morphology in the compatibilized PP/LCP blends had large influence on the mechanical properties. Differential scanning calorimeter (DSC) studies indicated no remarkable changes in the crystalline melting temperature of the blends with respect to that of pure PP. However, an increase in the softening range of the blends over that of PP was observed. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

The dynamic properties,temperature transitions,and thermal stability of poly (etherether ketone)-thermotropic liquid crystalline polymer blends

Differential scanning calorimetry, dynamic mechanical measurements, and thermal gravimetric analysis techniques have been used to thermally characterize blends of poly(etherether ketone)-thermotropic liquid crystalline polymer (LCP) based on hydroxybenzoic and hydroxynaphthoic acid (HBA/HNA). Based upon differential scanning calorimetry and dynamic mechanical measurements, these blends have been shown to be incompatible in the entire range of concentration. For these blends the glass transition temperature of both components does not change much with composition. Dynamic mechanical measurements performed under torsional and flexural modes of testing and different samples geometries indicate that the dynamic properties depend a lot on the above two factors. Anisotropy in these blends was studied by performing dynamic measurements in flow and transverse directions. The effect of orientation is found to be predominant. Dynamic mechanical properties tend to improve in the flow direction, whereas in the transverse direction they are found to decrease with increasing LCP concentration.     

Structural and Mechanical Studies of In-Situ Generated Poly(vinlylidene fluoride) Particle Comprising Poly(ethylmethacrylate) and Poly(methylmethacrylate) Ternary Films

The poly(vinlylidene fluoride) (PVDF) was incorporated within the compound matrix of poly(ethylmethacrylate) (PEMA)/poly(methylmethacrylate) (PMMA) using solution cast technique. The importance of PVDF in the miscibility of PEMA/PMMA matrix was investigated using FT-IR, DSC, SEM and AFM technique. Crystalline particle size of PVDF in PEMA/PMMA matrix was analyzed using XRD characterization. Single-phase compatibility with maximum crystallinity along with the maximum value of hardness was observed when PVDF/PMMA/PEMA were blended in equal weight ratio. The PVDF particle act as reinforcing material within the compound matrix of PEMA/PMMA, and hence, improves the properties of prepared ternary blends.     

Melt blending of polylactide and poly(methyl methacrylate): Thermal and mechanical properties and phase morphology characterization

Blends of polylactide with poly(methyl methacrylate), PLA/PMMA, were prepared by a semi‐industrial twin screw extruder and afterwards were injection molded. Blends were studied using different techniques as Fourier Transform Infrared Spectroscopy (FTIR), Dynamic Mechanical Analysis (DMA), Differential Scanning Calorimetry (DSC), Scanning Electron Microscopy (SEM), and mechanical properties by means of tensile and impact tests, were also studied. This work helped better understanding of apparently contradictory results reported in the literature for PLA/PMMA blends prepared by melt compounding. DSC first heating scan and DMA results showed partially miscible blends, whereas the second DSC heating scan showed miscible blends. For miscible blends, T_g values were predicted using Gordon‐Taylor equation. On the other hand, Small and Van Krevelen approaches were used to estimate the solubility parameters of neat PLA and neat PMMA, and Flory‐Huggins interaction parameter was calculated from solubility parameters. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42677.     

The study of morphology,thermal and thermo‐mechanical properties of compatibilized TPU/SAN blends

The compatibilizing efficiency of three different compatibilizers in thermoplastic polyurethane/styrene‐co‐acrylonitrile (TPU/SAN) blends was investigated after their incorporation via melt‐mixing. The compatibilizers studied were poly‐ε‐caprolactone (PCL), a mixture of polystyrene‐block‐polycaprolactone (PS‐b‐PCL) and polystyrene‐block‐poly(methyl methacrylate) (PS‐b‐PMMA), and a mixture of polyisoprene‐block‐polycaprolactone (PI‐b‐PCL) and polybutadiene‐block‐poly(methyl methacrylate) (PB‐b‐PMMA). All compatibilizers were synthesized by living anionic polymerization. Investigations of thermal and thermo‐mechanical properties performed by differential scanning calorimetry (DSC) and dynamic mechanical thermal analysis (DTMA), respectively, were systematically classified into two groups, i.e. blends of TPU or SAN with 20 wt% of different compatibilizers (so‐called limit conditions) and TPU/SAN 25/75 blends with 5 wt% of different compatibilizers. In order to determine the compatibilizer's location, morphology of TPU/SAN 25/75 blends was studied with transmission electron microscopy (TEM). Different compatibilization activity was found for different systems. Blends compatibilized with PCL showed superior properties over the other blends. Polym. Eng. Sci. 44:838–852, 2004. © 2004 Society of Plastics Engineers.     

Thermal and mechanical properties of poly(methyl methacrylate) and ethylene vinyl acetate copolymer blends

A series of poly(methyl methacrylate) (PMMA) blends have been prepared with different compositions viz., 5, 10, 15, and 20 wt % ethylene vinyl acetate (EVA) copolymer by melt blending method in Haake Rheocord. The effect of different compositions of EVA on the physico‐mechanical and thermal properties of PMMA and EVA copolymer blends have been studied. Differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA) and thermogravimetric analysis (TGA) has been employed to investigate the phase behavior of PMMA/EVA blends from the point of view of component specific interactions, molecular motions and morphology. The resulting morphologies of the various blends also studied by optical microscope. The DSC analysis indicates the phase separation between the PMMA matrix and EVA domains. The impact strength analysis revealed a substantial increase in impact strength from 19 to 32 J/m. The TGA analysis reveals the reduction in onset of thermal degradation temperature of PMMA with increase in EVA component of the blend. The optical microscope photographs have demonstrated the PMMA/EVA system had a microphase separated structure consisting of dispersed EVA domains within a continuous PMMA matrix. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Effect of multi‐walled carbon nanotubes on crystallization,thermal, and mechanical properties of poly(vinylidene fluoride)

Composites were prepared by solution blending poly(vinylidene fluoride) (PVDF) and multi‐walled carbon nanotubes (MWNTs). Fourier transform infrared spectroscopy (FTIR) and X‐ray diffraction (XRD) results showed that the crystalline structure of PVDF was changed by the addition of MWNTs and a MWNTs‐induced crystal transformation from α‐phase to β‐phase of PVDF was confirmed. With differential scanning calorimeter (DSC) and dynamic mechanic thermal analysis (DMA) techniques, thermal and mechanical properties of the composite films were examined. As the DSC results showed, addition of MWNTs would lead to the increased cooling crystallization temperature (T_c), implying that MWNTs nanoparticles could act as nucleating agents, which is further proved with the help of polarized optical microphotographs. On the other hand, the decreasing of D_d (degree of crystallinity) implied that the MWNTs networks can confine the crystallization of PVDF. Through the curve analysis of the dynamic mechanical measurements, it was found that the storage modulus (E′) is significantly enhanced, revealing that a strong interaction should exist between PVDF and MWNTs. POLYM. COMPOS., 2010. © 2009 Society of Plastics Engineers     

Investigation of the structural,thermal, mechanical,and optical properties of poly(methyl methacrylate) and poly(vinylidene fluoride) blends

In this investigation, poly(methyl methacrylate) (PMMA) and poly(vinylidene fluoride) (PVDF) blends (w/w) were prepared in a Brabender (South Hackensack, NJ) plasticorder with a thermoplastic mixing chamber (type W60) preheated at 180°C. These blends were further converted into films by a conventional solution casting method and characterized with Fourier transform infrared spectroscopy, differential scanning calorimetry, X‐ray diffraction, mechanical property measurements, impact strength testing, ultraviolet–visible spectroscopy, refractive‐index measurements, and contact‐angle study. The Fourier transform infrared results indicated that the compatibility between these two systems resulted from hydrogen bonding between the carbonyl group of PMMA and the CH₂ group of PVDF. The thermal analysis showed depressions in the glass‐transition temperature, melting temperature, and crystallization temperature. The heat of crystallization increased with an increase in the PVDF content in the blend. An increase in the heat of crystallization meant an increase in the crystallinity. An increase in the cooling rate increased the crystallization rate. The improvement in the mechanical properties of the blend films indicated that the observed behavior was ascribable to a more coherent structure of the blends due to strong specific interactions between PMMA and PVDF chains. The impact strength analysis revealed a substantial increase in the impact strength from 21.64 to 38.52 J/m. Optical absorption spectra suggested the presence of an optical band gap energy that increased with an increase in the PVDF content in the blend. The contact angle against water increased with the PVDF content in the blend film, and this was caused by the hydrophobicity of PVDF due to the CF₂ group of PVDF. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Polymer compatibility III. The system poly(methyl methacrylate)–poly(vinyl acetate). Characterization studies

Blends of poly(methyl methacrylate) (PMMA) and poly(vinyl acetate) (PVAc) were prepared by mixing the polymers in the melt and in the absence of a solvent. PMMA was the major constituent of the blend. The polymer blends were tested, using various methods, to determine if they are compatible as solids. Data obtained from dynamic mechanical and DSC measurements show that, when they are mixed under given Brabender mix conditions, the blends exhibit properties characteristic of polymer pairs compatible as solids. If the mix conditions are altered, a two-phase system is evidenced. Using micrographs obtained by light microscopy in phase contrast as criteria, two companion blends containing PMMA/PVAc 80/20 would be classified as incompatible as solids because of the differences in refractive index of PMMA and PVAc. The micrographs also show that, in the system that would otherwise be listed as compatible, the PVAc domains appear to be relatively uniform in size and distribution through the PMMA matrix. In its companion blend, large, irregularly shaped particles of PVAc which are poorly dispersed in the PMMA matrix are evident.     

Investigation on crystallization behavior and hydrophilicity of poly(vinylidene fluoride)/poly(methyl methacrylate)/poly(vinyl pyrrolidone) ternary blends by solution casting

Ternary blends composed of matrix polymer poly(vinylidene fluoride) (PVDF) with different proportions of poly(methyl methacrylate) (PMMA)/poly(vinyl pyrrolidone) (PVP) blends were prepared by solution casting. The crystallization behavior and hydrophilicity of ternary blends were characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), wide angle X‐ray diffraction (WAXD), differential scanning calorimetry (DSC), and contact angle test. According to morphological analysis, the surface was full of typical spherulitic structure of PVDF and the average diameter was in the order of 3 μm. The samples presented predominantly β phase of PVDF by solution casting. It indicated that the size of surface spherulites and crystalline phase had little change with the PMMA or PVP addition. Moreover, FTIR demonstrated special interactions among the ternary polymers, which led to the shift of the carbonyl stretching absorption band of PVP. On the other hand, the melting, crystallization temperature, and crystallinity of the blends had a little change compared with the neat PVDF in the first heating process. Except for the content of PVP containing 30 wt %, the crystallinity of PVDF decreased remarkably from 64% to 33% and the value of t_1/2 was not obtained. Besides, the hydrophilicity of PVDF was remarkably improved by blending with PMMA/PVP, especially when the content of PVP reached 30 wt %, the water contact angle displayed the lowest value which decreased from 98.8° to 51.0°. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Influence of fluorine interface to the crystallization of poly (vinylidene fluoride)/silicone rubber/fluororubber elastomeric tertiary blends via dynamical curing

ABSTRACT

We demonstrate the influence of fluorine interface to the crystallization of poly(vinylidene fluoride) (PVDF)/silicone rubber (SR)/fluororubber (FKM) tertiary dynamic curing blends. In contrast to PVDF/SR binary blend, the average size of PVDF spherulites turns smaller and the crystallization rate is lower in PVDF/SR/FKM tertiary blend when more fluororubber component was added into the blends at the same crystallization temperature. Incorporation of FKM does not change the crystalline form of PVDF in the blends. The resulting mechanical properties of tensile strength, flexural strength, Izod impact strength and elongation at break for PVDF/SR/FKM tertiary blends are enhanced compared with PVDF/SR binary blend.     

Toughening effect of poly(methyl methacrylate) on an immiscible poly(vinylidene fluoride)/polylactide blend

In this work, a mutually miscible third polymer, poly(methyl methacrylate) (PMMA), was incorporated into an immiscible poly(vinylidene fluoride)/polylactide (PVDF/PLA) blend (weight ratio 70:30). It was found that incorporation of PMMA in an appropriate amount (30–60 wt%) induced a marked improvement in fracture toughness. A five times enlargement of the elongation at break can be achieved by introducing 30 wt% PMMA. In order to understand the underlying toughening mechanism, SEM, dynamic mechanical analysis (DMA), XRD and DSC were applied to study the variations in morphology, the interaction between the three components and the crystallization behavior. SEM micrographs showed that the PMMA preferred to locate at the interface of PVDF and PLA, which was attributed to the mutual miscibility of PVDF with PMMA and PLA. Furthermore, a variety of thermal characteristics such as T_g and T_m induced by the entanglement of PVDF, PMMA and PLA at the interface were illustrated in DMA and DSC curves. Obviously, the interface consisting of the entanglement of PVDF, PLA and PMMA acted as a linkage to improve interfacial adhesion, which was regarded as the main toughening mechanism. This work provides a potential strategy to realize the interfacial enhancement of an immiscible blend via the incorporation of a mutually miscible third polymer. © 2016 Society of Chemical Industry     

Blends of amorphous and crystalline polylactides with poly(methyl methacrylate) and poly(methyl acrylate): a miscibility study

Blends of amorphous and crystalline polylactides (PDLA and PLLA) with poly(methyl methacrylate) (PMMA) and poly(methyl acrylate) (PMA) have been prepared. Thermal behaviour and miscibility of these blends along the entire composition interval were studied by differential scanning calorimetry (d.s.c.). The results were compared with those obtained by dynamic mechanical analysis (DMTA). Only one T_g was found in PDLA/PMA and PDLA/PMMA blends, indicating a high degree of miscibility in both systems. Nevertheless, the PDLA/PMMA blend presented enlargements of the T_g width at high PMMA contents. In this case, additional evidence of complete miscibility was obtained by studying the evolution of the enthalpic recovery peaks which appear after different thermal annealing treatments. When the polylactide used was semicrystalline (PLLA), once the thermal history of the blends had been destroyed, crystallization of PLLA was disturbed in both blends PLLA/PMMA and PLLA/PMA, but in a rather different fashion: in the first case crystallization was almost prevented while in the second one it was favoured. This behaviour was explained in terms of the effect of the higher stiffness as indicated by the value of T_g for PMMA compared to that for PMA.     

Nanophase morphology and crystallization in poly(vinylidene fluoride)/polydimethylsiloxane‐block‐poly(methyl methacrylate)‐block‐polystyrene blends

An approach to achieve confined crystallization of ferroelectric semicrystalline poly(vinylidene fluoride) (PVDF) was investigated. A novel polydimethylsiloxane‐block‐poly(methyl methacrylate)‐block‐polystyrene (PDMS‐b‐PMMA‐b‐PS) triblock copolymer was synthesized by the atom‐transfer radical polymerization method and blended with PVDF. Miscibility, crystallization and morphology of the PVDF/PDMS‐b‐PMMA‐b‐PS blends were studied within the whole range of concentration. In this A‐b‐B‐b‐C/D type of triblock copolymer/homopolymer system, crystallizable PVDF (D) and PMMA (B) middle block are miscible because of specific intermolecular interactions while A block (PDMS) and C block (PS) are immiscible with PVDF. Nanostructured morphology is formed via self‐assembly, displaying a variety of phase structures and semicrystalline morphologies. Crystallization at 145 °C reveals that both α and β crystalline phases of PVDF are present in PVDF/PDMS‐b‐PMMA‐b‐PS blends. Incorporation of the triblock copolymer decreases the degree of crystallization and enhances the proportion of β to α phase of semicrystalline PVDF. Introduction of PDMS‐b‐PMMA‐b‐PS triblock copolymer to PVDF makes the crystalline structures compact and confines the crystal size. Moreover, small‐angle X‐ray scattering results indicate that the immiscible PDMS as a soft block and PS as a hard block are localized in PVDF crystalline structures. © 2019 Society of Chemical Industry