Miscibility Of Polypropylene Research Articles

Structure and Properties of In-Situ Reactive Compatibilized Polypropylene/Poly (Butyl Methacrylate-Co-Hydroxyethyl Methacrylate) Blend Fibers

In this study, in-situ compatibilized polymer blends of polypropylene (PP) and poly (butyl methacrylate-co-hydroxyethyl methacrylate) P(BMA-co-HEMA) were prepared in a corotating twin screw extruder through the reactive extrusion of mixtures of PP, P(BMA-co-HEMA), butyl methacrylate, and benzoyl peroxide. In the process of reactive extrusion, butyl methacrylate and benzoyl peroxide were used as the monomer and the initiator, respectively. Thereafter the polymer blend was made into fibers via melt spinning. The miscibility of PP and P(BMA-co-HEMA) in the blend fibers was investigated using field emission scanning electron microscopy. The absorption percentage of the blend fibers for organic liquids and their remaining ratios after the absorption tests were also determined and used to prove the generation of the third phase. The changes in the fiber morphology during organic liquid absorption were observed using polarized light microscopy. In addition, the effect of the miscibility on the crystal structure and melting characteristic of the blend fibers were analyzed using wide-angle X-ray diffractometry and differential scanning calorimetry. Finally, the thermal stability of the blend fibers that was associated with the miscibility of PP and P(BMA-co-HEMA) in the blend fibers were characterized by using thermogravimetry and dynamic thermomechanical analysis.

Molecular dynamics and mesoscopic dynamics simulations for prediction of miscibility in polypropylene/polyamide-11 blends

► We investigated the miscibility of PP/PA11 blends by molecular simulations. ► The mesoscopic morphology of blends depends on the mixture compositions. ► Interaction parameters of MesoDyn simulations were obtained from MD simulations. The miscibility of polypropylene (PP)/polyamide-11 (PA11) blends were investigated by atomistic molecular dynamics (MD) and mesoscopic dynamics (MesoDyn) simulations. Five PP/PA11 blends (with the weight ratio at 90/10, 70/30, 50/50, 30/70 and 10/90) as well as pure PP and PA11 were examined. The Flory–Huggins interaction parameters, χ , which were computed for different blends and determined from the cohesive energy densities, were computed for different blends using atomistic simulations to predict blend miscibility. It was found that in the case of 90/10 PP/PA11 blend, miscibility was normally observed, but immiscibility was prevalent at higher compositions of PA11 component. The radial distribution functions g ( r ) of the inter-molecular carbon atomic pairs of PP–PA11, PP–PP and PA11–PA11 also indicate that 90/10 PP/PA11 is miscible, but at other compositions, these blends are immiscible. Kinetics of phase separation was examined by using density profiles calculated from the MesoDyn approach to examine miscibility/immiscibility aspects of the blends. All the simulations results are qualitatively consistent with the experimental results, and demonstrate that the modeling strategies in this study may provide a powerful tool for predicting miscibility and mesoscopic morphology of polymer blends.

Valorization of poly(butylene terephthalate) wastes by blending with virgin polypropylene: Effect of the composition and the compatibilization

AbstractBlends of recycled poly(butylene terephthalate) (PBT) parts obtained from scrapped cars, and virgin polypropylene (PP), were prepared in a twin‐screw extruder at different compositions. Selected compositions were also prepared with the presence of ethylene‐co‐glycidyl methacrylate copolymer (E‐GMA) and ethylene/methyl acrylate/glycidyl methacrylate terpolymer (E‐MA‐GMA) compatibilizers. The effect of the composition and the type of compatibilizer, as well as the mixing conditions, on the morphology phase, thermal, viscoelastic behavior, and mechanical properties of the blends has been investigated. Blends PP/PBT of various composition exhibit a coarse morphology and a poor adherence between both phases, resulting in the decrease of ductility, whereas at weak deformation, PBT reinforced the tensile properties of PP. Addition of E‐GMA and E‐MA‐GMA to the PP/PBT blend exhibited a significant change in morphology and improved ductility because of interfacial reactions between PBT end chains and epoxy groups of GMA that generate EG‐g‐PBT copolymer. Moreover, thermal and viscoelastic study indicated that the miscibility of PP and PBT has been improved further and the reactions were identified. The E‐MA‐GMA results in the best improvement of ductility. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers

Miscibility and crystallisation of polypropylene–linear low density polyethylene blends

Crystallisation, morphology and miscibility of polypropylene (PP) and linear low density polyethylene (LLDPE) blends were studied by polarised optical microscopy connected to a computer with digital image processing and analysis. In particular the effects of LLDPE and its melt flow index (MFI) on the kinetics of PP crystallisation was investigated through establishing a relationship between nucleation density, spherulitic growth rate and overall crystallisation growth rate. All the blends contained 20% by mass of PP and the LLDPEs used were of the similar grades. The crystallisation of PP was controlled to occur isothermally at temperatures where LLDPEs were in molten state. It was found that, the PP crystallised as open-armed diffuse spherulites, similar to those observed in the miscible blends, suggesting that the PP and the LLDPE may be miscible at some temperatures. The nuclei density, spherulite growth rate and overall crystallisation rate of PP decreased significantly in the blends, indicating that the LLDPE retarded crystallisation of PP, possibly due to various reasons such as the dilution of PP by LLDPE (LLDPE as a solvent in molten state), hindrance of viscous LLDPE to the PP crystallisation front, and decreased supercooling degree because of the miscibility between the PP and LLDPE. This provided further evidence that the PP and the LLDPE could be miscible at crystallisation temperatures selected. In addition, the spherulite growth rate of PP decreased with a decrease in MFI of LLDPE while the MFI of LLDPE had negligible effect on the nuclei density, showing that the diffusion process controlled overall crystallisation rate when the nucleation density were similar for blends with various MFI. This further confirmed that PP and LLDPE were miscible at elevated temperatures since the more viscous LLDPE (lower MFI) reduced the crystallisation rate of PP at a greater degree.

Mixing of Isotactic and Syndiotactic Polypropylenes in the Melt

The miscibility of polypropylene (PP) melts in which the chains differ only in stereochemical composition has been investigated by two different procedures. One approach used detailed local information from a Monte Carlo simulation of a single chain, and the other approach takes this information from a rotational isomeric state model devised decades ago, for another purpose. The first approach uses PRISM theory to deduce the intermolecular packing in the polymer blend, while the second approach uses a Monte Carlo simulation of a coarse-grained representation of independent chains, expressed on a high-coordination lattice. Both approaches find a positive energy change upon mixing isotactic PP (iPP) and syndiotactic PP (sPP) chains in the melt. This conclusion is qualitatively consistent with observations published recently by Mülhaupt and co-workers. The size of the energy change on mixing is smaller in the MC/PRISM approach than in the RIS/MC simulation, with the smaller energy change being in better agreement with the experiment. The RIS/MC simulation finds no demixing for iPP and atactic polypropylene (aPP) in the melt, consistent with several experimental observations in the literature. The demixing of the iPP/sPP blend may arise from attractive interactions in the sPP melt that are disrupted when the sPP chains are diluted with aPP or iPP chains.

Morphology of nylon 6/polypropylene blends compatibilized with maleated polypropylene

AbstractTransmission electron microscopy (TEM) was used to examine the morphology of blends of nylon 6 and polypropylene (PP) containing various maleated polypropylenes (PP‐g‐MA). The size of the dispersed polypropylene particles decreases as the content of maleic anhydride in the PP‐g‐MA increases for binary blends of nylon 6 and the maleated polypropylenes. Ternary blends of nylon 6, PP, and PP‐g‐MA show morphologies that depend on the content of maleic anhydride of the PP‐g‐MA and on the miscibility of PP and PP‐g‐MA. Blends where PP and PP‐g‐MA are immiscible show a bimodal distribution of particle sizes. Miscibility of the PP and PP‐g‐MA was determined by TEM using a special staining technique. Experimental observations of miscibility were further corroborated by thermodynamic calculations. The morphology of the ternary blends was also found to be dependent on the ratio of PP/PP‐g‐MA. By changing this ratio it was possible to induce drastic changes of morphology, going from a continuous nylon 6 phase to a continuous PP phase at a fixed composition. The mechanical properties of these blends were found to be dependent on their morphology. ©1995 John Wiley & Sons, Inc.