Phase morphology,thermomechanical, and crystallization behavior of uncompatibilized and PP‐g‐MAH compatibilized polypropylene/polystyrene blends

In this article, we discuss the phase morphology, thermal, mechanical, and crystallization properties of uncompatibilized and compatibilized polypropylene/polystyrene (PP/PS) blends. It is observed that the Young's modulus increases, but other mechanical properties such as tensile strength, flexural strength, elongation at break, and impact strength decrease by blending PS to PP. The tensile strength and Young's modulus of PP/PS blends were compared with various theoretical models. The thermal stability, melting, and crystallization temperatures and percentage crystallinity of semicrystalline PP in the blends were marginally decreased by the addition of amorphous PS. The presence of maleic anhydride‐grafted polypropylene (compatibilizer) increases the phase stability of 90/10 and 80/20 blends by preventing the coalescence. Hence, finer and more uniform droplets of PS dispersed phases are observed. The compatibilizer induced some improvement in impact strength for the blends with PP matrix phase, however fluctuations in modulus, strength and ductility were observed with respect to the uncompatibilized blend. The thermal stability was not much affected by the addition of the compatibilizer for the PP rich blends but shows some decrease in the thermal stability of the blends, where PS forms the matrix. On the other hand, the % crystallinity was increased by the addition of compatibilizer, irrespective of the blend concentration. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42100.     

Fractionated crystallization of dispersed PA6 phase of PP/PP‐g‐MAH/PA6 blends

Fractionated crystallization behavior of dispersed PA6 phase in PP/PA6 blends compatibilized with PP‐g‐MAH was investigated by scanning electron microscopy (SEM), differential scanning calorimeter (DSC), polarized light microscopy (PLM), and wide‐angle X‐ray diffraction (WAXD) in this work. The lack of usual active heterogeneities in the dispersed droplet was the key factor for the fractionated crystallization of PA6. The crystals formed with less efficient nuclei might contain more defects in the crystal structures than those crystallized with the usual active nuclei. The lower the crystallization temperature, the lesser the perfection of the crystals and the lower crystallinity would be. The fractionated crystallization of PP droplets encapsulated by PA6 domains was also observed. The effect of existing PP‐g‐MAH‐g‐PA6 copolymer located at the interface on the fractionated crystallization could not be detected in this work. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 91: 3742–3755, 2004     

Non-isothermal crystallization kinetics of calcium carbonate-filled β-crystalline phase polypropylene composites

The non-isothermal crystallization behaviour of high purity β-phase and α-phase polypropylene (PP) and their calcium carbonate-filled composites was investigated by means of differential scanning calorimetry. High purity β-PP polymer was prepared by adding an effective β-nucleator consisting of equal amounts of pimelic acid and calcium stearate. The crystallization temperature and crystallization rate coefficient of pure β-PP polymer were considerably higher than those of the α-PP polymer. This was due to the β-PP polymer containing nucleating agents, which act as nuclei for β-spherulites. The calcium carbonate content had little or no effect on the crystallization rate coefficient and Ozawa exponent of the β-phase PP in the composites. On the other hand, the crystallization temperature, crystallization rate coefficient and Ozawa exponent of the α-phase PP composites depended on the calcium carbonate loading. The effect of calcium carbonate additions on the crystallization of α-PP and β-PP is discussed. ©1997 SCI     

Polyblend CPP and Bionolle with PP‐g‐MAH as compatibilizer. II. Biodegradability

The biodegradability of Bionolle and a CPP/Bionolle blend in two biotic environments, that is, soil and a lipase‐enzyme solution, were evaluated using the mechanical properties and weight‐loss data. It was noted that upon soil burial the tensile strength and elongation at break of polyblends were significantly reduced, particularly after 3 months. The time of complete loss of strength as predicted from the curve‐fit model was found sequentially to be 6.80, 5.03, 4.84, 11.49, and 140.25 months for Bionolle, compatibilized Bionolle, and CPP/Bionolle (25/75), (50/50), and (75/25), respectively. Meanwhile, the weight loss of polyblends during soil burial were observed to generally increase with increasing Bionolle content. Even a synergistic effect on the weight loss was shown by compatibilized Bionolle and CPP/Bionolle (25/75). Additionally, the time for complete weight loss as estimated from the curve‐fit model was 12.57, 7.33, 7.01, and 13.90 months for Bionolle, compatibilized Bionolle, and CPP/Bionolle (25/75) and (50/50), respectively. From the enzymatic degradation, it was recognized that in the early stage of biodegradation both the amorphous phase and the crystalline parts were randomly attacked. It was found that the weight loss that resulted from enzymatic degradation was satisfactorily described by a generalized kinetic curve derived from a first‐order reaction. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 72: 1283–1290, 1999     

Polyblend CPP and Bionolle with PP‐g‐MAH as compatibilizer: I. Compatibility

Melt‐blending polypropylene‐co‐ethylene (CPP) and Bionolle with polypropylene‐grafted maleic anhydride (Modic) as a compatibilizer was done. The effect of variational Modic concentration on the compatibility was evaluated using ultimate strength data and SEM micrographs, while the true molecular compatibility over all blend composition ranges was examined by calculating and comparing the theoretical value of glass transition temperature with the experimental value. The results suggest that 15 wt % Modic appears to be an optimum concentration, as indicated by a relatively high ultimate strength over all blend composition ranges and formation of the so‐called cocontinuous phase in the blend morphology. Additionally, the value of glass transition temperature calculated theoretically agrees quite well with the experimental value, indicating that at a certain blend composition, the blend sample was found almost compatible. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 72: 1277–1282, 1999     

Reactive compatibilization of an immiscible polyester/polyolefin blend with PP‐g‐MAH and PMPI dual compatibilizers

Blends of a polyester hot melt resin and a poly‐α‐olefin hot melt resin were modified using the reactive compounding technique. The effects of the compatibilizers were evaluated by studying the mechanical properties, the morphology, and the thermal properties of the modified blends. A pronounced compatibilizing effect was obtained with dual compatibilizers composed of maleated polypropylene and poly[methylene (phenylene isocyanate)] (PMPI). The addition of 1 phr of PMPI was sufficient to improve the elongation and tensile strength. From the results, it is anticipated that PMPI can be used as an efficient coupler to enhance the compatibility of immiscible polyester/polyolefin blends. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40232.     

Thermal evaluation of PHB/PP‐g‐MA blends and PHB/PP‐g‐MA/vermiculite bionanocomposites after biodegradation test

This study aimed to evaluate the thermal behavior of polyhydroxybutyrate (PHB)/polypropylene grafted with maleic anhydride (PP‐g‐MA) blends and PHB/PP‐g‐MA/vermiculite bionanocomposites submitted to the biodegradation test according to ASTM G 160‐03. The blends and bionanocomposites were prepared by melt intercalation method using a single screw extruder, and then, compression molded. The thermal analyzes were performed by thermogravimetry (TG) and differential scanning calorimetry. It was verified the decrease of onset degradation temperature and the melting temperature mainly after 86 days of exposure to the simulated soil. This behavior was more pronounced in bionanocomposites because of interactions between the maleic anhydride groups and the clay favoring biodegradation, making the systems more amorphous and propitious to the attack of microorganisms. POLYM. ENG. SCI., 56:555–560, 2016. © 2016 Society of Plastics Engineers     

Preparation and characterization of nano/micro‐calcium carbonate particles/polypropylene composites

A new kind of polypropylene (PP)/CaCO₃ composites was prepared on a twin screw extruder with the nanoparticle content of 5 wt % and the 2500 mesh microparticle content of 15 wt %. The mechanical property of four different samples [pure PP (1) , PP filled with 15 wt % microCaCO₃ particle composites (2) , PP filled with 5 wt % nanoCaCO₃ particle composites (3) and PP filled with micro/nano‐CaCO₃ complex size particle composites (4) ] was investigated through tensile tests, notched Izod impact tests and SEM. The results indicated that the sample 4 had the best mechanical property. The proofs of SEM showed that the high impact energy could lead to debonding and creating microcavitation between the nanoparticle and polymer interface if the polymer was filled with the nanoparticles. This process could absorb a lot of mechanical failure energy, but too much mechanical failure energy would lead to the enlargement of microcavitation and the destruction of the composites in sample 3 . In sample 4 , the microparticle could be used to prevent the enlargement of microcavitation in the matrix polymer under the higher impact failure energy. In this article, the model of the impacting failure process of micro/nanoCaCO₃/PP composites was established. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Compatibilization of intumescent flame retardant/polypropylene composites based on α‐methacrylic acid grafted polypropylene

A phosphoric acid–pentaerythritol–melamine copolymer was selected as an intumescent flame retardant (IFR). The influence of α‐methacrylic acid grafted polypropylene (PP‐g‐MAA) on the properties and compatibility of IFR/PP composites was studied. The results obtained from mechanical tests and scanning electron microscopy showed that PP‐g‐MAA was a true coupling agent for IFR/PP blends, but it did not change the necessary flame retardancy. The cocrystallization between bulk PP and PP segments of PP‐g‐MAA was proved by wide‐angle X‐ray diffraction analysis. A flow test showed that the flow behaviors of composites in the melt were those of a pseudoplastic liquid and it was very small for PP‐g‐MAA and affected the rheological behavior of the PP/IFR composite. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 3128–3132, 2002; DOI 10.1002/app.10099     

Fracture of ultrafine calcium carbonate/polypropylene composites

The strength and fracture properties of a polypropylene filled with ultrafine calcium carbonate (0.07 μm) have been studied in the composition range of 0 to 40 percent by volume. Untreated and surface treated (with stearic acid and a titanate coupling agent) grades have been considered. The untreated filler caused a decrease of toughness whereas a maximum, at ∼10 percent, was observed for the treated filler. The fracture energy was analyzed in terms of the crack pinning model. Due to the very small size of particles the pinning contribution proved to be negligible.     

Influence of m‐isopropenyl‐α,α‐dimethylbenzyl isocyanate grafted polypropylene on the interfacial interaction of wood‐flour/polypropylene composites

In this article, the effects of m‐isopropenyl‐α,α‐dimethylbenzyl isocyanate grafted polypropylene (m‐TMI‐PP) on the interfacial interaction of wood‐flour/polypropylene (WF/PP) were investigated by means of scanning electron microscopy (SEM), differential scanning calorimetry (DSC), thermogravimetry, dynamic rheological analysis, and mechanical properties tests. The experimental results demonstrated that m‐TMI‐PP greatly improved the interfacial interaction between WF and PP. According to the DSC results, m‐TMI‐PP made the crystallization temperature and the crystallization degree of PP in WF/m‐TMI‐PP/PP decrease when compared with WF/PP composite without m‐TMI‐PP, but it was still higher than pure PP. These results demonstrated that WF presented the nucleate effect for the crystallization of PP and m‐TMI‐PP improved the interfacial adhesive, which restrained the mobility of PP chain. The rheological analysis indicated that the complex viscosity, storage, and loss modular of WF/PP composite increased, and the tan δ decreased with the addition of m‐TMI‐PP. This was attributed to the strong improvement effects of m‐TMI‐PP on the interfacial interaction of the composites, and was further confirmed by the mechanical properties tests and SEM analysis of the composites. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Mechanical properties and morphology of PP/ABS blends compatibilized with PP‐g‐2‐HEMA

Polypropylene (PP) and acrylonitrile–butadiene–styrene blends of different composition were prepared using a single‐screw extruder. The binary blend of PP/ABS was observed to be incompatible and shows poor mechanical properties. PP‐g‐2‐hydroxyethyl methacrylate (2‐HEMA) was used as a compatibilizer for the PP/ABS blends. The ternary compatibilized blends of PP/ABS/PP‐g‐2‐HEMA showed improvement in the mechanical properties. Electron micrographs of these blends showed a homogeneous and finer distribution of the dispersed phase. The mechanical performance increased particularly in the PP‐rich blend. The 2.5‐phr (part per hundred of resin) compatibilizer was observed to bring improvement to the properties. The suitability of various existing theoretical models for the predication of the tensile moduli of these blends was examined. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 72–78, 2003     

Fabrication and properties of surface‐modified β‐Si3N4 whiskers reinforced dental resin composites

In this article, three kinds of surface‐modified methods were used to treat β‐Si₃N₄ whiskers before being incorporated into Bis‐GMA/TEGDMA dental resin matrix in order to improve the whiskers' reinforcing effect. The experimental results showed that composites with directly heat‐treated and then silanized β‐Si₃N₄ whiskers had the best reinforcing effect. They had flexural strength of 160 ± 7.0 MPa (mean ± SD; n = 6), compressive strength of 371 ± 1.4 MPa (mean ± SD; n = 5) and HRA of 48.4 ± 0.5(mean ± SD; n = 5), respectively. In addition, water sorption and solubility test demonstrated that the composites were reliable to use as the dental restoration materials. Therefore, the directly heat‐treated and then silanized β‐Si₃N₄ whiskers (better than β‐Si₃N₄ whiskers mixed with SiO₂ nanoparticles or SiO₂ sols) were most suitable fillers to reinforce dental resin composites. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Investigation of rare earth ions adsorption properties of PP‐g‐AA

Acrylic acid (AA) was grafted onto the powdered isotactic polypropylene (i‐PP) with the electron‐beam‐induced preirradiation method (Chen, D.‐T.; Shi, N.; Xu, D.‐F. J Appl Polym Sci 1999, 73, 1357–1362). Some rare earth ions, including Sm³⁺, Nd³⁺, Eu³⁺, Gd³⁺, and Er³⁺, were adsorbed onto the grafting product PP‐g‐AA. The properties of Sm³⁺ adsorbed were investigated in detail. These properties include the influences of the adsorption time, acidity, ion concentration of the solution, grafting yield of AA onto i‐PP, and temperature on the quantity and efficiency of the ion adsorption. Some kinetic and thermodynamic equilibrium constants of the adsorption were obtained in the experiments. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 76: 1549–1553, 2000     

Melting and crystallization behaviors,morphology, and mechanical properties of β‐polypropylene/polypropylene‐graft‐maleic anhydride/calcium sulfate whisker composites

The melting and crystallization behaviors, morphology, and mechanical properties of polypropylene (PP)/surface‐treated calcium sulfate (CaSO₄) whisker (T‐CSW), β‐PP/T‐CSW, and β‐PP/polypropylene‐graft‐maleic anhydride (PP‐g‐MAH)/T‐CSW composites had been investigated via differential scanning calorimetry (DSC), wide angle X‐ray diffraction (WAXD), polarized light microscopy (PLM), scanning electron microscopy (SEM), and mechanical tests. We found that T‐CSW was an α‐nucleating agent and increased the crystallization temperatures of PP, but PP‐g‐MAH and high loadings of T‐CSW had weakly negative effects on the crystallization rates of PP. The T‐CSW restrained the formation of β‐spherulites, and the spherulitic size decreased in the composites. PP‐g‐MAH improved the compatibility and adhesion between T‐CSW and the matrix. The notched impact strength was improved, and the tensile strength was enhanced at low levels of T‐CSW, while the flexural modulus was weakened for β‐PP/T‐CSW and β‐PP/PP‐g‐MAH/T‐CSW composites versus PP/T‐CSW composites. POLYM. COMPOS., 37:2121–2132, 2016. © 2015 Society of Plastics Engineers     

Crystallization and melting of highly filled polypropylene composites prepared with surface‐treated fillers

Polypropylene (PP) composites with high filler content have been prepared with surface‐treated fillers. The effect of the filler is twofold; nucleation of crystallization occurs, though the PP is also adsorbed onto the filler thereby retarding its motion. Differential scanning calorimetry has been used to study the crystallization of the PP. Melting and recrystallization during melting has been characterized by differential scanning calorimetry. The properties of the composites are more than an additive combination of the filler and polymer. In the case of highly filled composites, the morphology of the PP is important in limiting brittleness and for the strength of the interface between filler and polymer. Surface treatment of the filler has been found to have a significant control over the morphology and properties of the composites. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 79: 1942–1948, 2001     

Calcium dicarboxylates nucleation of β‐polypropylene

Seven dicarboxylates of calcium were synthesized. The effect of dicarboxylate on the formation of β‐form polypropylene was investigated by X‐ray diffraction. Calcium pimelate, calcium suberate, calcium phthalate, and calcium terephthalate have been found to be an effective β‐nucleator. The K_x values of the isotatic propylene samples with 0.5 wt % of the nucleators above are 0.95, 0.96, 0.93, and 0.62, respectively. Calcium succinate, calcium adipate, and calcium sebacate behave invalidly on the nucleating of the β‐phase. We conducted an investigation on the affect of particle shape, crystal form, and crystallinity upon the level of the β‐form. The X‐ray diffraction of the effective nucleators reveals a common character that their first reflection locate at the d‐spacing between 10 to 13 Å, indicating structural similarity of the nucleators with β‐polypropylene. The nucleation mechanism is explained by the cooperative effect of the nonpolar and polar part of nucleating agents in the crystallization of polypropylene. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 633–638, 2002     

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.