Interaction and properties of epoxy‐amine system modified with poly(phthalazinone ether nitrile ketone)

An epoxy based on the tetraglycidyl 4,4′‐diaminodiphenyl‐ methane (TGDDM)/bisphenol A type novolac(F‐51) cured with 4,4′‐diaminidiphenysulfone (DDS) has been modified with Poly (phthalazinone ether nitrile ketone)(PPENK). The interaction between the PPENK and epoxy resin have been investigated by differential scanning calorimetry (DSC), FT‐IR, and dynamic mechanical analysis (DMA). The thermal and mechanical properties were characterized by thermogravimetric analysis (TGA), thermomechanical analysis (TMA), flexural, impact strength, and the critical stress intensity factor tests. The results showed that a large number of physical crosslinks formed by intermolecular and intramolecular hydrogen bonding indeed existed in the TGDDM/F‐51/PPENK blends. These interactions gave good compatibility between PPENK and epoxy resin. So that any phase separation had not been detected by DMA and scanning electron microscope (SEM). Beyond that the interaction could also be a benefit to the thermal and mechanical properties. Compared with the neat epoxy resin, the critical stress intensity factor values reached the maximum at 10‐phr PPENK, as well as the impact strength. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 42938.     

Thermal properties and crystallinity of PCL/PBSA/cellulose nanocrystals grafted with PCL chains

Bionanocomposite films of poly(?‐caprolactone) (PCL) and poly(butilene succinate‐co ‐adipate) (PBSA) blends with cellulose nanocrystals (CNW) grafted with PCL chains (CNW‐g ‐PCL) were prepared by solution casting and their thermal properties and crystallinity were studied. The CNW surface was modified with PCL chains by grafting “from” approaches, in an effort to improve their compatibility with the polymer blends. The grafting efficiency was evidenced by FTIR and TGA analysis. The acicular morphology of CNW‐g ‐PCL was characterized by SEM. The TGA results showed an increase in the thermal stability of the CNW grafted with PCL chains. The PCL/PBSA blends showed higher thermal stability in comparison with the neat polymers and PCL/PBSA/CNW‐g ‐PCL bionanocomposites. DSC results showed the CNW‐g ‐PCL act as a nucleating agent in the bionanocomposites. Additionally, a better interaction of the CNW‐g ‐PCL in the blends of 30/70 composition in comparison with the blends of 50/50 composition was characterized. The results obtained for aforementioned films prepared by solution casting encourage the production of such bionanocomposites by melt compounding (extrusion), aiming the achievement of new bionanocomposites materials with improved thermal and mechanical properties. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 44493.     

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     

Mechanical and thermal properties of poly(butylene succinate)/poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) biodegradable blends

Biodegradable polymer blends of poly(butylene succinate) (PBS) and poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) (PHBV) were prepared with different compositions. The mechanical properties of the blends were studied through tensile testing and dynamic mechanical thermal analysis. The dependence of the elastic modulus and strength data on the blend composition was modeled on the basis of the equivalent box model. The fitting parameters indicated complete immiscibility between PBS and PHBV and a moderate adhesion level between them. The immiscibility of the parent phases was also evidenced by scanning electron observation of the prepared blends. The thermal properties of the blends were studied through differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The DSC results showed an enhancement of the crystallization behavior of PBS after it was blended with PHBV, whereas the thermal stability of PBS was reduced in the blends, as shown by the TGA thermograms. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42815.     

Mechanical and thermal properties of glass bead–filled nylon‐6

The mechanical and thermal properties of glass bead–filled nylon‐6 were studied by dynamic mechanical analysis (DMA), tensile testing, Izod impact, thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC) tests. DMA results showed that the incorporation of glass beads could lead to a substantial increase of the glass‐transition temperature (T_g) of the blend, indicating that there existed strong interaction between glass beads and the nylon‐6 matrix. Results of further calculation revealed that the average interaction between glass beads and the nylon‐6 matrix deceased with increasing glass bead content as a result of the coalescence of glass beads. This conclusion was supported by SEM observations. Impact testing revealed that the notch Izod impact strength of nylon‐6/glass bead blends substantially decreased with increasing glass bead content. Moreover, static tensile measurements implied that the Young's modulus of the nylon‐6/glass bead blends increased considerably, whereas the tensile strength clearly decreased with increasing glass bead content. Finally, TGA and DSC measurements indicated that the thermal stability of the blend was obviously improved by incorporation of glass beads, whereas the melting behavior of the nylon‐6 remained relatively unchanged with increasing glass bead content. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 1885–1890, 2004     

Studies on the curing behavior,thermal, and mechanical properties of epoxy resin-co-amine-functionalized lead phthalocyanine

A high performance copolymer was prepared by using epoxy (EP) resin as matrix and 3,10,17,24-tetra-aminoethoxy lead phthalocyanine (APbPc) as additive with dicyandiamide as curing agent. Fourier-transform infrared spectroscopy, dynamic mechanical analysis (DMA), differential scanning calorimetric analysis (DSC), and thermogravimetric analysis (TGA) were used to study the curing behavior, curing kinetics, dynamic mechanical properties, impact and tensile strength, and thermal stability of EP/APbPc blends. The experimental results show that APbPc, as a synergistic curing agent, can effectively reduce the curing temperature of epoxy resin. The curing kinetics of the copolymer was investigated by non-isothermal DSC to determine kinetic data and measurement of the activation energy. DMA, impact, and tensile strength tests proved that phthalocyanine can significantly improve the toughness and stiffness of epoxy resin. Highest values were seen on the 20 wt% loading of APbPc in the copolymers, energy storage modulus, and impact strength increased respectively 388.46 MPa and 3.6 kJ/m², T_g decreased 19.46°C. TGA curves indicated that the cured copolymers also exhibit excellent thermal properties.     

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     

Mechanical,electrical, and dielectric properties of polyvinylidene fluoride/short carbon fiber composites with low‐electrical percolation threshold

In this investigation, polyvinylidene fluoride (PVDF)/short carbon fiber (SCF) composites have been prepared by solution casting technique to enhance electrical and dielectric properties with very low‐electrical percolation threshold (0.5 phr SCF). The effect of SCF content on mechanical, thermal and morphological properties of the composites have also been investigated. The mechanical properties of the composites are found to reduce compared to neat PVDF due to poor polymer–filler interaction which can be concluded from FESEM micrographs showing poor bonding between PVDF and SCF. The PVDF/SCF composites exhibit either positive temperature coefficient effect of resistivity or negative temperature coefficient effect of resistivity depending on the loading of SCF in the polymer matrix. The change in conductivity during heating–cooling cycle for these composites shows electrical hysteresis along with electrical set. The melting point of the composites marginally increases with the increase in fiber loading in PVDF matrix as evidenced from DSC thermograms. X‐ray diffraction analysis reveals the crystallinity of PVDF decreases with the increase in SCF loading in matrix polymer. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39866.     

The effect of acid content on the poly(furfuryl) alcohol/cellulose composites

Cellulose/poly(furfuryl alcohol) (PFA) composites were prepared via in situ polymerization process using p‐toulene sulfonic acid as a catalyst. Cellulose was extracted from cotton fibers using chemical treatments with basic media of NaOH, NaClO₂ and KOH. Acid hydrolysis at different concentrations (30, 40 and 50%) of sulphuric acid was used and the final suspended cellulose was incorporated in PFA. The treatments of the cotton fibers ensued to higher crystalline cellulose which was proportional to sulphuric acid contents. Scanning electron microscopy studies (SEM) results showed a poor interfacial interaction when 50% acid content was used for hydrolyses. The effect of fiber reinforcement on thermal and dynamic mechanical properties of the composites was investigated using thermogravimetric analysis (TGA) and dynamic mechanical analysis (DMTA). The TGA results showed higher thermal stability of cellulose/PFA composites as compared to the neat PFA. The DMA results showed that the incorporation of the cellulose fibers imparts significant enhancement in the storage modulus of the PFA matrix. There was also the clear decrease in intensity of the tan peak of the composites compared to the neat PFA. POLYM. COMPOS., 37:2434–2441, 2016. © 2015 Society of Plastics Engineers     

Artificial weathering effect on the structure and properties of polypropylene/polyamide‐6 blends compatibilized with PP‐g‐MA

The degradation of uncompatibilized and compatibilized PP/PA‐6 (70/30 wt %) with PP‐g‐MA under accelerated UV light was investigated using Fourier Transform Infrared Spectroscopy (FTIR) spectroscopy, melt flow index (MFI) tester, tensile test, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and scanning electron microscopy (SEM). FTIR analysis of the structure of the compatibilized and uncompatibilized blends after exposure to UV light showed the formation of photoproducts corresponding to both components. The MFI and mechanical results obtained revealed that photooxidation started primarily in PA‐6 rather than PP. In addition, the uncompatibilized blends exhibited a higher degradation rate compared to neat polymers for long exposure time, and the addition of PP‐g‐MA increased slightly their ageing rate in accordance with TGA data. Further, DSC analysis showed an increase in the crystallinity index and a decrease in the melting temperature of PP and PA‐6 after UV exposure either as neat polymers or as blend components. SEM micrographs of the cryo‐fractured surfaces of the samples illustrated the formation of cracks and fractures after UV irradiation. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41722.     

Weak interaction,marginal miscibility,and ring‐band spherulites in blends of poly(vinylidene fluoride) with polyesters

Fourier transform infrared (FTIR) spectroscopy, optical microscopy (OM), and differential scanning calorimetry (DSC) techniques were used to probe phase behavior and interactions in blends of poly(vinylidene fluoride) (PVDF) and polyesters [poly(trimethylene adipate) (PTA) and poly(pentamethylene adipate) (PPA)] of relatively low crystallizability. DSC thermal analysis and OM characterization proved that PVDF was miscible with PTA and PPA with a low lower critical solution temperature. Small negative values of the interaction parameters (χ₁₂ = ?0.13 for a PVDF/PPA blend) were obtained with the melting‐point depression method. FTIR spectroscopy results revealed that interactions between ? CF₂ of PVDF and the ? C?O group of the polyester were weak, in agreement with the thermal analysis results. An increase in the coarseness and/or ring‐band spacing further provided supportive evidence that miscibility did exist between the polyester and PVDF constituents in the blends. Pattern changes in ring‐band spherulites of the miscible blends further substantiated the favorable, though weak, interactions between the PVDF and polyester constituents. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Mechanical properties and morphologies of polypropylene composites synergistically filled by styrene‐butadiene rubber and silica nanoparticles

The mechanical properties and morphologies of PP/SBR/SiO₂ nanocomposites have been studied using mechanical testing, wide‐angle X‐ray diffraction (WAXD), polarizing optical microscopy (POM), scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). The mechanical properties of neat polypropylene can be considerably improved by synergistically filling with SiO₂ and SBR nanoparticles, especially for the notched Izod impact strength. The results from the WAXD, POM, SEM, DSC, and TGA measurements reveal that: (i) the β‐phase crystal structure of PP is formed when SiO₂ and SBR nanoparticles are synergistically filled with polypropylene and its formation plays a role for the enhancement of the impact strength for PP/SBR/SiO₂ nanocomposites; (ii) the dispersion of SiO₂ and SBR nanoparticles in PP/SBR/SiO₂ composites is homogeneous, indicating that synergistic incorporating method decreases the aggregation of nanoparticles and thus increases the sites for dissipation of shock for impact energy in PP/SBR/SiO₂ nanocomposites; (iii) the thermal analysis shows high thermal stability for the PP/SBR/SiO₂ nanocomposites. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Cure kinetics and properties of epoxy/dicyanate blends

The cure behavior and properties of epoxy/dicyanate blends containing a stoichiometric amount of an amine curing agent for epoxilde groups were investigated as a function of blend composition. Differential scanning calorimetry (DSC) was used to investigate the dynamic and isothermal cure behavior of the blends. The cure rate of the blend increased with increasing dicyanate content. A second order autocatalytic reaction mechanism described the cure kinetics of the blends. The kinetic parameters were determined by fitting the dynamic DSC data to the model kinetic equation. The k₁₀ and E₁ values were mainly affected by the change of dicyanate content. The glass transition temperature of the blend decreased with increasing dicyanate content. The thermal decomposition characteristics of the blends were investigated by thermogravimetric analysis (TGA). Dynamic mechanical analysis (DMA) and thermal mechanical analysis (TMA) were used to investigate the mechanical properties of the blends. With increasing dicyanate content, the cure rate increased but the thermal and mechanical properties of the cured blends were not improved.     

Property-morphology relationships of polymethylmethacrylate/polyvinylidenefluoride blends

An investigation was conducted to establish property-morphology relationships in polymethylmethacrylate/polyvinylidenefluoride (PMMA/PVDF) blends. All blends were compounded in a twin-screw extruder and then processed by injection molding Mechanical properties of blends of various compositions were studied by dynamic mechanical and impact strength measurements. The presence of crystalline regions in blends was determined by Differential Scanning Calorimetry (DSC). Morphology of fracture surfaces of blends was studied by Spinning Electron Microscopy (SEM). PMMA/PVDF blends were found to form compatible mixtures over a wide range of blend composition. Changes in dynamic mechanical properties upon annealing were found to be a direct function of blond morphology. Electron microscopic evidence showed no signs of phase separation. DSC measurements detected crystalline regions in all blends containing 40 percent or more (by weight) PVDF.     

Non-isothermal crystallization behavior of poly(vinylidene fluoride)/ethylene–vinyl acetate copolymer blends

Non-isothermal crystallization behavior of poly(vinylidene fluoride) (PVDF) and ethylene–vinyl acetate (EVA) copolymer and their binary blends with different blending ratios were investigated by the use of differential scanning calorimetry (DSC). With the increasing cooling rates, PVDF, EVA and their binary blends showed wide crystallization temperature range and high crystalline enthalpy. Jeziorny and Mo’s models were applied to calculate non-isothermal crystallization kinetics parameters of neat PVDF, EVA and their binary blends. By Jeziorny method, the crystallization process of neat PVDF, EVA and PVDF/EVA = 7/3 blend can be divided into two parts: primary and secondary crystallization processes. The Avrami exponent n ₁ indicated that the primary crystallization process was a mixture model of three-dimensional and two-dimensional space extensions. In comparison, PVDF/EVA = 5/5 and PVDF/EVA = 3/7 blends showed a single crystallization process. Through Mo’s analysis, faster cooling rate was demanded to reach higher relative crystallinity. Crystallization rate coefficient (CRC) was used to describe the effect of crystallization rates on the interaction between PVDF and EVA. CRC reached a maximum value when the mass ratio of PVDF and EVA was 7/3. The maximum CRC values of PVDF system and EVA system were 98.1 and 179.9 h^?1, respectively. The activation energy was closely related to the extent of conversion and the neat samples had a maximum value of crystallization activation energy. This was consistent with the observation for the parameters from Jeziorny analysis and could be correlated to the heterogeneous nucleation.     

Preparation of epoxidized cardanol butyl ether as a novel renewable plasticizer and its application for poly(vinyl chloride)

A new type of plasticizer, epoxidized cardanol butyl ether (ECBE), was synthesized via etherification and epoxidation. Successful synthesis was confirmed from Fourier transform infrared, ¹H NMR and ¹³C NMR spectra. The obtained product was evaluated by adding it to poly(vinyl chloride) (PVC) incorporated with dioctyl phthalate (DOP). Mechanical and thermal properties of PVC blends were studied using tensile testing, thermogravimetric analysis (TGA) and dynamic mechanical analysis (DMA). Processability, migration and volatility of plasticizing systems were also investigated. Tensile tests found a maximum increase of 17.8% in elongation at break. DMA results indicated that glass transition temperature shifted to lower temperature with a maximum decrease of 5.76 °C. TGA results revealed that PVC blends with higher content of ECBE had higher thermal stability; initial degradation temperature, 50% weight loss temperature and the first peak degradation temperature increased by 15.3, 14.8 and 4.1 °C, respectively. Processing time was extended from 11.56 to 59.94 min. The plasticizing performance of migration and volatility resistance were higher than those of neat DOP. © 2016 Society of Chemical Industry     

Compatibilization Effects of PE-g-MA on Mechanical,Thermal and Swelling Properties of High Density Polyethylene/Natural Rubber/Thermoplastic Tapioca Starch Blends

Effect of polyethylene grafted maleic anhydride (PE-g-MA) on mechanical, thermal and swelling characteristic of high density polyethylene (HDPE)/natural rubber (NR)/thermoplastic tapioca starch (TPS) blends were studied. The measurements from differential scanning calorimetric (DSC), dynamic mechanical analysis (DMA) and thermogravimetric analysis (TGA), proved the effectiveness of PE-g-MA as compatibilizer in improving the miscibility between HDPE/NR – TPS blends. A decrement in crystallinity index was found after adding PE-g-MA. It is due to restriction in mobility of the HDPE chains. In the presence of PE-g-MA, the blends have better thermal stability. On top of that, the storage modulus which is reflected to the blend stiffness also increased as indicated the improvement in HDPE/NR – TPS interaction.     

Interfacial Interaction Analysis of Blends of Poly(vinylidene fluoride) and Poly(ethylene–butylacrylate–glycidyl methacrylate) Compatibilized by Poly(butylene succinate): Morphologies,Rheological Behavior,and Mechanical Properties

Poly(vinylidene fluoride) (PVDF) and poly(ethylene–butylacrylate–glycidyl methacrylate) (PTW) are polymers with weak interfacial adhesion. Blends based on PVDF and PTW (50/50?w/w) with poly(butylene succinate) (PBS) (0, 1, 3, 5, 7?wt%) are obtained by compression molding. The estimation of interfacial interaction among PVDF, PTW, and PBS and the properties of PVDF/PTW blends are investigated. The optimal content of PBS to form a co-continuous morphology in PVDF/PTW blends is proposed, indicating that the beneficial effect of PBS (7?wt%) on interfacial adhesion is observed. Overall, estimating interfacial adhesion is a critical issue for designing PVDF/PTW blend with excellent performance, which has a prospect in coating.     

Enhancement in the thermal and dynamic mechanical properties of high performance liquid crystalline epoxy composites through uniaxial orientation of mesogenic on carbon fiber

In this work, a high performance liquid crystalline epoxy composite was prepared and the effect of the alignment of LCE with long lateral substituent on the carbon fiber surface curing at low temperature on fracture toughness, dynamic mechanical, and thermal properties of liquid crystalline epoxy with lateral substituent (LCE6) was investigated by polarized optical microscopy (POM), wide angle X‐ray diffraction measurements (WAXS), dynamic mechanical analysis (DMA), thermogravimetric (TGA), and scanning electron microscopy (SEM). Curing degree of the composite was observed by FTIR. The experimental results indicate that the fracture toughness, glass transition temperature (T_g), thermal stability, degradation kinetics are associated with the alignment of LCE6 along long axis of carbon fiber. The alignment of LCE6 on carbon fiber surface can increase mesogen network density, which leads to higher fracture toughness, higher thermal stability, increase of the activation energies and higher T_g of the composite. The dynamic mechanical analysis shows that the compoaite possesses extremely higher dynamic storage moduli, which indicates that this LCE6/DDM/CF composite can be a high performance composite. Thus, the compoaite can be a potential candidate for advanced composites. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40363.     

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