Modification of poly(propylene) by grafted polyester‐amide‐based dendritic nanostructures with the aim of improving its dyeability

Fiber‐graded poly(propylene) was modified by polyester‐amide‐based dendritic nanostructures with the aim of improving its dyeability. Two different dendritic polymers were used and the dendritic nanostructures were formed in situ via reactive blending with maleic anhydride‐modified poly(propylene). Samples were chosen exploiting a 4‐component mixture design. Thermal, morphological, and rheological characterizations showed domains with different size and distribution were formed and primary properties of the dendritics determined the characteristics of the resulted domains. Morphological parameters were quantified by digital analysis of scanning electron microscope images. Thermal and rheological behavior also demonstrated good agreements with the inferred morphology of the formed dendritic domains. The modified samples were then dyed with dispersed dyestuffs. A variety of substantivities were obtained, and some of the modified samples showed a significant enhancement in dyeing properties. A predictive model was developed for K/S ratio, where K and S are absorption and scattering coefficients of the Kubelka‐Munk one constant theory, respectively. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Compatibility in immiscible polysulfone/poly(ethylene terephthalate) blends

Polysulfone (PSU)/poly(ethylene terephthalate) (PET) blends were obtained by direct injection molding across the composition range. Their phase behavior, thermal properties, morphology, and mechanical properties were measured. The blends were composed of a pure PSU amorphous phase and either a pure PET phase in PSU‐poor blends, or a PET‐rich phase with some dissolved PSU in PSU‐rich blends. The morphology of the dispersed phase was mostly spherical with some elongated particles in the PET‐rich blends. A slight synergistic behavior was observed in the Young's modulus, mainly in the 90/10 blend, which is probably due to orientation effects. The presence of some broken particles indicated some interfacial adhesion. The ductility values were approximately linear with composition. This was generally the case in PSU‐rich blends, and was attributed to the higher level of PSU in the PET‐rich phase. Although embrittlement was seen in blends with 30% of the second component, the ductility of the two pure components did not significantly decrease after annealing due to the presence of low amounts (up to 10%) of another component of the blend. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 2193–2200, 2004     

Compatibilization of immiscible blends of polypropylene and isosorbide containing copolyester with silica nanoparticles

In the present study, compatibilization of immiscible blends of polymers was investigated based on the Pickering emulsion concept with various mixing procedures. Silica nanoparticles were incorporated into poly (1,4-cyclohexanedimethylene isosorbide terephthalate) (PEICT)/isotactic polypropylene (iPP) blends. Localization of nanoparticles was effectively modified by varying mixing procedures. Relocation of hydrophilic silica occurred in a secondary mixing procedure with the PEICT, which has relatively high affinity when primarily mixed with iPP. The final location of the silica nanoparticles was confirmed by SEM images. SEM and an optical microscope were used to follow morphological change. By simply changing the mixing procedure, the hydrophilic silica nanoparticles were able to perform the role of a morphology modifier successfully without modifying the surface characteristics. The mechanical properties and crystallization behavior were also compared depending on the surface characteristics of the silica nanoparticles and their final localization.     

Preparation of sulfonated polypropylene and its dyeability: Thiol as a functionalization template of polypropylene

A two-step process has been invented to prepare sulfonated polypropylene from chlorinated polypropylene via thiolation and successive oxidation to enhance the dyeability of polypropylene. With a short thiolation reaction time of 3 h in an N-methyl-2-pyrrolidone solution, 1.7–20.5% sulfur can be incorporated into a polypropylene bulk effectively. Chlorine–thiol substitution and hydrosulfide conversion have been examined with elemental analysis, and their behaviors as a function of the SH/Cl ratio can be explained with an equilibrium model of hydrosulfide and accessible chlorine in a given timescale. Oxidation of thiol has been performed successfully with hydrogen peroxide. The evolution of oxidation intermediates such as sulfoxide, sulfone, sulfinic acid, and sulfonic acid can be identified by Raman and Fourier transform infrared analyses. Sulfonated polypropylene can be stained by a basic dye very effectively, and its dye uptake reaches 190 mmol of dye/kg of polymer for 3.6 mmol of sulfur/g of polymer. This dye uptake is 20 times more effective than that of chlorinated polypropylene on a molar basis. Thus, it is clear that a modification can be performed effectively to enhance the dyeability of polypropylene. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Uniaxial orientation and tensile properties of poly(ethylene terephthalate)/poly(ethylene-2,6-naphthalate) blends

Amorphous films of poly(ethylene terephthalate)/poly(ethylene-2,6-naphthalate) (PET/PEN) blends with different blend ratios were uniaxially drawn by solid-state coextrusion and the structure development during solid state deformation was studied. As-prepared blends showed two T_gs. The lower T_g was ∼72 °C, independent of the blend ratio. In contrast, the higher T_g increased with increasing PEN content. Thus, the coextrusion was carried out around the higher T_g of the sample. At a given draw ratio of 5, which was close to the achievable maximum draw ratio, the tensile strength of the drawn samples from the initially amorphous state increased gradually with increasing PEN content. On the other hand, the tensile modulus was found to decrease initially, reaching a minimum at 40-60 wt% PEN, and then increased as the PEN content increased. The results indicate that we can get the drawn films with a moderate tensile modulus and a high tensile strength. The drawn samples from the blends containing 40-60 wt% of PEN showed a maximum elongation at break, and a maximum thermal shrinkage around 100 °C. Also, the degree of stress-induced crystallinity showed a broad minimum around the blend ratio of 50% of PEN. These morphological characteristics explained well the effects of blend ratio on the tensile modulus and strength of drawn PET/PEN blend films.     

Novel multimonomer‐grafted polypropylene preparation and application in polypropylene/poly(vinyl chloride) blends

A novel grafted polymer was prepared in one step through free‐radical melt grafting in a single‐screw extruder. It was shown that the addition of styrene (St) to the melt‐grafting system as a comonomer could significantly enhance the grafting degree of methyl methacrylate (MMA) onto polypropylene (PP) and reduce the degradation of the PP matrix by means of Fourier transform infrared and melt flow rate testing, respectively. Then, the potential of using multimonomer‐grafted PP, which was designated PP‐g‐(St‐co‐MMA), as the compatibilizer in PP/poly(vinyl chloride) (PVC) blends was also examined. In comparison with PP/PVC blends, the average size of the dispersed phase was greatly reduced in grafted polypropylene (gPP)/PVC blends because of the addition of the PP‐g‐(St‐co‐MMA) graft copolymer. The tensile strength of the gPP/PVC blends increased significantly, and the impact strength was unchanged from that of the pure PP/PVC blends. The results of differential scanning calorimetry and scanning electron microscopy suggested that the compatibility of the PP/PVC blends was improved. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Compatibilization of polypropylene/nylon 6 blends with a polypropylene solid‐phase graft

The compatibilization of polypropylene (PP)/nylon 6 (PA6) blends with a new PP solid‐phase graft copolymer (gPP) was systematically studied. gPP improved the compatibility of PP/PA6 blends efficiently. Because of the reaction between the reactive groups of gPP and the NH₂ end groups of PA6, a PP‐g‐PA6 copolymer was formed as a compatibilizer in the vicinity of the interfaces during the melting extrusion of gPP and PA6. The tensile strength and impact strength of the compatibilized PP/PA6 blends obviously increased in comparison with those of the PP/PA6 mechanical blends, and the amount of gPP and the content of the third monomer during the preparation of gPP affected the mechanical properties of the compatibilized blends. Scanning electron microscopy and transmission electron microscopy indicated that the particle sizes of the dispersed phases of the compatibilized PP/PA6 blends became smaller and that the interfaces became more indistinct in comparison with the mechanical blends. The microcrystal size of PA6 and the crystallinity of the two components of the PP/PA6 blends decreased after compatibilization with gPP. The compatibilized PP/PA6 blends possessed higher pseudoplasticity, melt viscosity, and flow activation energy. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 420–427, 2004     

Production of polymeric membranes made of polypropylene,poly(ethylene‐co‐vinyl acetate), and poly(vinyl alcohol)

In this study, we prepared and characterized membranes containing polypropylene, poly(ethylene‐co‐vinyl acetate) (EVA), and poly(vinyl alcohol) (PVA). The production process involved blend extrusion and calendering followed by solvent extraction by toluene and water of the EVA and PVA phases. Morphology studies involving scanning electron microscopy determined the pore size distribution at the surface and in the internal regions of the membrane. The resulting membrane properties were related to the processing variables (extension rate, process temperature, and solvent extraction methods) and blend composition. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 3275–3286, 2004     

Heterogeneous blends of recycled poly(ethylene terephthalate) with impact modifiers: phase structure and tensile creep

Several types of photomicrographs have concurrently shown that impact modifiers (IMs) form particles (on a micrometre scale) which are evenly dispersed in a recycled poly(ethylene terephthalate) (PET) matrix; their adhesion to the latter is high enough that fracture surfaces (produced in liquid nitrogen) do not follow the interface. An essential part of the tensile creep of PET corresponds to the elastic time‐independent component; the time‐dependent component is rather limited, even if relatively high stresses are applied. Thus, the tensile compliance of PET is virtually independent of the applied stress, which indicates linear viscoelastic behaviour. The compliance of PET/IM blends (93/7, 90/10, 85/15 (by weight)) grows with the IM content and its time‐dependence becomes more visible. The effects of the two types of IM used in this study seem to be practically identical from the viewpoint of dimensional stability of the blends. The logarithm of compliance grows with the logarithm of time faster than linearly, and this tendency becomes more apparent with increasing fraction of IM. Even if the strain‐induced free volume is taken into account, a noticeable upswing of the compliance for longer creep periods (t > 1000 min) is evident. This cannot be interpreted as a consequence of the flow, because the recovery following the creep has proved the complete reversibility of the previous deformation. A simple empirical equation is proposed, which provides a plausible prediction of the creep behaviour of PET with dispersed impact modifiers. Copyright © 2004 Society of Chemical Industry     

A preliminary study of blends of bisphenol a polycarbonate and poly(ethylene terephthalate)

The microstructure of blends of bisphenol A polycarbonate (PC), and poly(ethylene terepthalate) (PETP) has been studied by solvent extraction, infrared spectrophotometry, differential scanning calorimetry and dynamic mechanical thermal analysis. The blends appear to contain two amorphous phases over the whole composition range. The tensile behaviour and the Charpy impact strength of some of the blends have been determined, before and after heat treatment at 125°C for 18 hours. Improved performance of the blends, compared with that of the homopolymers PC and PETP, has been demonstrated.     

Morphology and mechanical properties of polypropylene/high‐impact polystyrene blends from postconsumer plastic waste

The compatibilizing effect of the triblock copolymer poly(styrene‐b‐ethylene‐co‐butylene‐b‐styrene) (SEBS) on the morphological and mechanical properties of virgin and recycled polypropylene (PP)/high‐impact polystyrene (HIPS) blends was studied, with the properties optimized for rigid composite films. The components of the blend were obtained from municipal plastic waste, PP being acquired from mineral water bottles (PP_b) and HIPS from disposable cups. These materials were preground, washed only with water, dried with hot air, and ground again (PP_b) or agglutinated (HIPS). Blends with three different weight ratios of PP_b and HIPS (6:1, 6:2, and 6:3) were prepared, and three different concentrations of SEBS (5, 6, and 7 wt %) were used for investigations of its compatibilizing effect. Scanning electron microscopy showed that SEBS reduced the diameter of dispersed HIPS particles in the globular and fibril shapes and improved the adhesion between the disperse phase and the matrix. However, SEBS interactions with PP_b and HIPS influenced the mechanical properties of the compatibilized PP_b/HIPS/SEBS blends. An adequate composition of PP/HIPS, for both virgin and recycled blends, for applications in composite films with characteristics similar to those of synthetic paper was obtained with a minimal amount of SEBS and a maximal HIPS/PP ratio in the range of concentrations studied. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2861–2867, 2003     

Blends of polypropylene with poly(cis‐butadiene) rubber. II. Small‐angle X‐ray scattering studies of the phase structure of immiscible blends of polypropylene with poly(cis‐butadiene) rubber

Pressed films of the blends of polypropylene (PP) with poly(cis‐butadiene) rubber (PcBR) were studied by IR spectra, small‐angle X‐ray scattering, and scanning electron microscopy. The problem of the interaction between different macromolecules in the blends of PP/PcBR is discussed by melt‐mixing at a temperature of 210°C using IR. X‐ray scattering from the relation of the phase was analyzed using Porod's law, and the interface layer thickness was calculated. The immiscibility of the blends of PP/PcBR was proved. The structure parameters, the correlation distance a_c, average chord lengths l?, and radius of gyration R?_g were obtained by the Debye–Buech statistical theory of scattering. Porod's index was calculated and the shape of the dispersed phase is discussed in relation to Porod's index in the blends. The morphology and structure of the blends were investigated by scanning electron microscopy. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2088–2094, 2002     

Thermal behavior and morphological and rheological properties of polypropylene and novel elastomeric ethylene copolymer blends

The thermal behavior including melting and crystallization behavior and morphological and rheological properties of the blends based on an isotactic polypropylene and a novel maleated elastomeric ethylene copolymer were investigated in this work. The addition of an elastomer to polypropylene (PP) was found not to change the PP crystalline structure significantly when cooled quickly from the melt. On recrystallization at a lower cooling rate, the elastomer promotes the formation of β?pseudohexagonal PP in PP‐rich blends. In elastomer‐rich compositions, heterogeneous nucleation is hindered and homogeneous nucleation takes place. These phenomena are revealed by morphology observation: that, with increasing of the elastomer content, the system undergoes PP continuous, dual‐phase continuity and PP‐dispersed morphologies. The blend viscosity at a low shear rate range increases continuously with increasing elastomer content and shows positive deviations from the additivity rule. In the terminal zone, the dynamic storage modulus of the blends shows positive deviation from the simple mixing rule and the maximum deviation lies in the composition range of dual‐phase continuity which could be caused by a large increase in the interfacial tension. The Cox–Merz rule does not hold for the blends because of the two‐phase heterogeneous structure and its variation in steady and oscillatory shear flow. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 3430–3439, 2002     

Morphology and mechanical properties of polypropylene and poly(ethylene‐co‐methyl acrylate) blends

The morphology and mechanical properties of isotactic polypropylene (iPP) and poly(ethylene‐co‐methyl acrylate) (EMA) blends were investigated. Various EMA copolymers with different methyl acrylate (MA) comonomer content were used. iPP and EMA formed immiscible blends over the composition range studied. The crystallization and melting reflected that of the individual components and the crystallinity was not greatly affected. The size of the iPP crystals was larger in the blends than those of pure iPP, indicating that EMA may have reduced the nucleation density of the iPP; however, the growth rate of the iPP crystals was found to remain constant. The tensile elongation at break was greatly increased by the presence of EMA, although the modulus remained approximately constant until the EMA composition was greater than 20%. EMA with a 9.0% MA content provided the optimum effect on the mechanical properties of the blends. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 175–185, 2003     

Study on thermoplastic polyurethane/polypropylene (TPU/PP) blend as a blood bag material

Blends with different ratios of thermoplastic polyurethane/polypropylene (TPU/PP) were prepared by melt mixing using an internal Haake mixer. Properties of the blends were investigated using SEM micrographs of cryofractures and measurement of the mechanical strength, water absorption, cell culture, and platelet adhesion in vitro tests, which were compared with those of PVC blood bags. The effect of the addition of the ethylene–vinyl acetate (EVA) copolymer on the TPU/PP blend properties was investigated. The results indicated that a TPU/PP/EVA = 80/20/5 blend can be used as a new blood bag material. It was observed that the blend is homogeneous with higher mechanical strength than that of the commercial PVC blood bag. This blend also showed a compatible cell response in contact with L929 fibroblast cells and fewer tendencies to interaction with platelets compared to the PVC blood bag. Although the blends were immissible and no chemical reaction at the interface could be found, the blood compatibility of the blends were improved. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2496–2501, 2003     

Microstructure and crystallization of melt‐mixed poly(ethylene terephthalate)/poly(ethylene isophthalate) blends

Physical blends of poly(ethylene terephthalate) (PET) and poly(ethylene isophthalate) (PEI), abbreviated PET/PEI (80/20) blends, and of PET and a random poly(ethylene terephthalate‐co‐isophthalate) copolymer containing 40% ethylene isophthalate (PET₆₀I₄₀), abbreviated PET/PET₆₀I₄₀ (50/50) blends, were melt‐mixed at 270°C for different reactive blending times to give a series of copolymers containing 20 mol % of ethylene isophthalic units with different degrees of randomness. ¹³C‐NMR spectroscopy precisely determined the microstructure of the blends. The thermal and mechanical properties of the blends were evaluated by DSC and tensile assays, and the obtained results were compared with those obtained for PET and a statistically random PETI copolymer with the same composition. The microstructure of the blends gradually changed from a physical blend into a block copolymer, and finally into a random copolymer with the advance of transreaction time. The melting temperature and enthalpy of the blends decreased with the progress of melt‐mixing. Isothermal crystallization studies carried out on molten samples revealed the same trend for the crystallization rate. The effect of reaction time on crystallizability was more pronounced in the case of the PET/PET₆₀I₄₀ (50/50) blends. The Young's modulus of the melt‐mixed blends was comparable to that of PET, whereas the maximum tensile stress decreased with respect to that of PET. All blend samples showed a noticeable brittleness. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 3076–3086, 2003     

Additive effect of poly(ethylene oxide) on polypropylene/fibrous cellulose composite: Effects of additive amount of poly(ethylene oxide) on Young's modulus and morphology

In this work, the additive effects of the poly(ethylene oxide) (PEO) on the Young's moduli of two kinds of polypropylene (PP)/fibrous cellulose (FC) composite were studied using the Kerner–Nielsen equation. In the case of the PP/maleated PP (MAPP)/FC + PEO composite, all the values of the moduli with the various PEO contents were in good agreement with the theoretical values obtained from the Kerner–Nielsen equation. Whereas the moduli of the PEO/FC + PP/MAPP composite followed the Kerner–Nielsen equation about 6 vol % of the PEO content and then unexpectedly deviated. In the scanning electron microscopy (SEM) observation, the PP/MAPP/FC + PEO composite was found to have a sea‐island morphology corresponding to the PP/MAPP/FC matrix and the PEO phase. This morphology had been unchanged against the increase of the PEO content. Whereas in the case of the PEO/FC + PP/MAPP composite, the SEM micrographs showed that that the interface between the FC and the PP became worse with the increase of the PEO content, indicating that the formation of the PP/MAPP/FC matrix was blocked by the excess PEO. The deviation of the Young's moduli from the Kerner–Nielsen equation was due to the blocking of the PEO. It was found that the adequate combination of the PEO and the MAPP was able to supply the increase of the toughness of the PP/FC composite by investigating the dependence of the PEO/FC + PP/MAPP composite on the MAPP content. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Miscibility and melting behavior of poly(ethylene terephthalate)/poly(trimethylene terephthalate) blends

The miscibility and melting behavior of binary crystalline blends of poly(ethylene terephthalate) (PET)/poly(trimethylene terephthalate) (PTT) have been investigated with differential scanning calorimetry and scanning electron microscope. The blends exhibit a single composition‐dependent glass transition temperature (T_g) and the measured T_g fit well with the predicted T_g value by the Fox equation and Gordon‐Taylor equation. In addition to that, a single composition‐dependent cold crystallization temperature (T_cc) value can be observed and it decreases nearly linearly with the low T_g component, PTT, which can also be taken as a valid supportive evidence for miscibility. The SEM graphs showed complete homogeneity in the fractured surfaces of the quenched PET/PTT blends, which provided morphology evidence of a total miscibility of PET/PTT blend in amorphous state at all compositions. The polymer–polymer interaction parameter, χ₁₂, calculated from equilibrium melting temperature depression of the PET component was ?0.1634, revealing miscibility of PET/PTT blends in the melting state. The melting crystallization temperature (T_mc) of the blends decreased with an increase of the minor component and the 50/50 sample showed the lowest T_mc value, which is also related to its miscible nature in the melting state. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Effect of talc on the properties of polypropylene/ethylene/propylene/diene terpolymer blends

In the present study, the effect of talc content on the mechanical, thermal, and microstructural properties of the isotactic polypropylene (i‐PP) and elastomeric ethylene/propylene/diene terpolymer (EPDM) blends were investigated. In the experimental study, five different talc concentrations, 3, 6, 9, 12, and 15 wt %, were added to i‐PP/EPDM (88/12) blends to produce ternary composites. The mechanical properties such as yield and tensile strengths, elongation at break, elasticity modulus, izod impact strength for notch tip radius of 1 mm, and hardness with and without heat treatments and thermal properties, such as melt flow index (MFI), of the ternary composites have been investigated. The annealing heat treatment was carried out at 100°C for holding time of 75 h. From the tensile test results, an increased trend for the yield and tensile strengths and elasticity modulus was seen for lower talc contents, while elongation at break showed a sharp decrease with the addition of talc. In the case of MFI, talc addition decreased the MFI of i‐PP/EPDM blends. It was concluded that, taking into consideration, mechanical properties and annealing heat treatment, heat treatment has much more effect on higher yield and tensile strengths, elongation at break, elasticity modulus, impact strength, and hardness. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 3033–3039, 2006     

Mechanical properties of Mg(OH)2/polypropylene composites modified by functionalized polypropylene

Modified Mg(OH)₂/polypropylene (PP) composites were prepared by the addition of functionalized polypropylene (FPP); and acrylic acid (AA) and by the formation of in situ FPP. The effects of the addition of FPP and AA and the formation of in situ FPP on the mechanical properties of Mg(OH)₂/PP composites were investigated. Experimental results indicated that the addition of Mg(OH)₂ markedly reduced the mechanical properties of PP. The extent of reduction in notch impact strength of PP was higher than that in flexural strength and tensile strength. However, tensile modulus and flexural modulus increased with increased Mg(OH)₂ content. The addition of FPP facilitated the improvement in the flexural strength and tensile strength of Mg(OH)₂/PP composites. The higher the Mg(OH)₂ content was, the more significant the effect of FPP was. The incorporation of AA resulted in further increased mechanical properties, in particular the flexural strength, tensile strength, and notch impact strength of Mg(OH)₂/PP composites containing high levels of Mg(OH)₂. It not only improved mechanical properties but also increased the flame retardance of Mg(OH)₂/PP composites. Although the mechanical properties of composites modified by the formation of in situ FPP were lower than those of composites modified by only the addition of AA in the absence of diamylperoxide, the mechanical properties did not decline with increased Mg(OH)₂ content. Moreover, the mechanical properties increased with increasing AA content. The addition of an oxidation resistant did not influence the mechanical properties of the modified Mg(OH)₂/PP composites. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2139–2147, 2003