COMPATIBILIZATION AND STRUCTURE OF POLY(PROPYLENE) NYLON-12 BLENDS

In this paper, scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and wide-angle X-ray diffraction (WAXD) were used to study the structure and compatibilization of poly(propylene) (PP)/nylon-12 (PA 12) blends. The compatibilizatio

The characterization of the interfacial reaction in polyamide 1010 poly(propylene)-graft-(glycidylmethacrylate) blends

Binary blends of polyamide 1010/poly(propylene) and polyamide 1010 (PA1010)/poly(propylene)-graft-(glycidyl methacrylate) (PP-g-GMA) were prepared. The epoxy groups in PP-g-GMA react with the amino end-groups in PA1010, thus a PA1010-graft-PP copolymer is formed and acts as a compatibilizer between PA1010 and PP-g-GMA. The reaction was confirmed by electron spectroscopy for chemical analysis (ESCA) and attenuated total reflection (ATR)-FTIR spectroscopic analysis, and also evaluated by the stability of the suspension obtained by dissolving the blends in formic acid and by the morphologies of the blends.

Crystallization behavior of poly(propylene)/polyamide 1010 blends using poly(propylene)-graft glycidyl methacrylate as compatibilizer

Polyamide 1010/poly(propylene) (PA1010/PP) blends were investigated with and without the addition of poly(propylene)-graft-glycidyl methacrylate (PP-g-GMA). The effect of the compatibilizer on the thermal properties and crystallization behavior was determined by differential scanning calorimetry and wide-angle X-ray diffraction. From the results it is found that the crystallization of PA 1010 is significantly affected by the presence of PP-g-GMA. PP/PA 1010 (75/25) blends containing higher amounts of PP-g-GMA show concurrent crystallization at the crystallization temperature of PP. Isothermal crystallization kinetics also were performed in order to investigate the influence of the compatibilized process on the nucleation and growth mechanism. In the PP/PA 1010 (25/75) blends, concurrent crystallization behavior was not observed, even though the amount of PPg-GMA was high.

EPITAXIAL CRYSTALLIZATION OF TRANS-1,4-POLYBUTADIENE ON HIGHLY ORIENTED ISOTACTIC POLY(PROPYLENE) FILMS

Epitaxial crystallization of trans-1,4-polybutadiene (PBD) on highly oriented isotactic poly(propylene) (iPP) has been investigated at different crystallization temperatures and rates. From electron microscopy and electron diffraction, it is confirmed that epitactic growth of the low-temperature modification (monoclinic) with microcrystals of PBD on the iPP films takes place with their chain directions about +/- 50-degrees apart. No epitaxial relationship occurs between the high-temperature modification (hexagonal) of PBD and the iPP substrate. Thermal analyses of PBD-PP layered films indicate that the epitaxy has an important effect on the formation of the high-temperature modification of PBD.

Time-resolved synchrotron SAXS observations on sheared syndiotactic poly(propylene) crystallization process

The in situ crystallization kinetics of syndiotactic poly(propylene) (sPP) has been investigated by synchrotron small-angle X-ray scattering (SAXS). The structure evolutions during the isothermal crystallization of sPP with different shear rates have been observed. The results show that shear accelerates the process of crystallization kinetics. Even under low shear rate, the lamellae can be distinctly oriented. In contrast, the lamellar parameters such as the long period, lamellar thickness, and the scattering invariant 0 can change obviously only under high shear rate.

Regio-regular structure high molecular weight poly(propylene carbonate) by rare earth ternary catalyst and Lewis base cocatalyst

Lewis base modification strategy on rare earth ternary catalyst was disclosed to enhance nucleophilic ability of active center during copolymerization of carbon dioxide and propylene oxide (PO), poly(propylene carbonate) (PPC) with H-T linkages over 83%, and number-average molecular weight (M-n) up to 100 kg/mol was synthesized at room temperature using Y(CCl3OO)(3)-ZnEt2-glycerine catalyst and 1,10-phenanthroline (PHEN) cocatalyst. Coordination of PHEN with active Zinc center enhanced the nucleophilic ability of the metal carbonate, which became more regio-specific in attacking carbon in PO, leading to PPC with improved H-T linkages.

Fixation of carbon dioxide into aliphatic polycarbonate, cobalt porphyrin catalyzed regio-specific poly(propylene carbonate) with high molecular weight

Cobalt porphyrin complex ((TPPCoX)-X-III) (TPP = 5, 10, 15, 20-Tetraphenylporphyrin; X = halide) in combination with ionic organic ammonium salt was used for the regio-specific copolymerization of propylene oxide and carbon dioxide. A turnover frequency of 188 h(-1) was achieved after 5 h, and the byproduct propylene carbonate was successfully controlled to below 1%, where the obtained poly(propylene carbonate) (PPC) showed number average molecular weight (M-n) of 48 kg/mol, head-to-tail content of 93%, and carbonate linkage of over 99%.

Electron-beam irradiation on poly(propylene carbonate) in the presence of polyfunctional monomers

Poly(propylene carbonate) (PPC) showed predominantly degradation under electron-beam irradiation, accompanied by deterioration of its mechanical performance due to sharp decrease of the molecular weight. Crosslinked PPC was prepared by addition of polyfunctional monomer (PFM) to enhance the mechanical performance of PPC. When 8 wt% of PFM like triallyl isocyanurate (TAIL) was added, crosslinked PPC with a gel fraction of 60.7% was prepared at 50 kGy irradiation dose, which showed a tensile strength at 20 degrees C of 45.5 MPa, whereas it was only 38.5 MPa for pure PPC. The onset degradation temperature (T-i) and glass transition temperature (T-g) of this crosslinked PPC was 246 degrees C and 45 degrees C, respectively, a significant increase related to pure PPC of 211 degrees C and 36 C. Therefore, thermal and mechanical performances of PPC could be improved via electron-beam irradiation in the presence of suitable PFM.

Effect of copolymerized ethylene unit on the crystallization behavior of poly(propylene-co-ethylene)s

The crystallization behavior of two kinds of commercial poly(propylene-co-ethylene)s (PPE1, PPE2) with similar average molecular weight and molecular weight distribution, isotacticity and copolymerized ethylene unit content and their fractions was investigated by differential scanning calorimetry (DSC), transmission electron microscopy (TEM) and polarized optical microscopy (POM) techniques. The results indicate that the PPE1 isothermally crystallized films possess thicker and less cross-hatched lamellar structure than those of the PPE2. As for the fractionated samples, the thin films of low temperature (less than or equal to 90 degreesC) fractions (PPE1-80, PPE2-80) of both PPE1 and PPE2 exhibit similar crystallization behavior, while for the high temperature ( greater than or equal to 95 degreesC) fractions (PPE1-108, PPE2-108), the crystalline morphology has marked differences. Compared with PPE2-108, the PPE1-108 isothermally crystallized thin films possess thicker lamellae and less crosshatched lamellar structure, while for the fibrous crystal number, the former is less than that of the latter. The main reason to create the crystallization behavior differences between the two PPEs and their fractions is due to the effect of molecular chain structure, i.e. the different distribution of copolymerized ethylene unit in polypropylene chains.

Effect of the gamma-form crystal on the thermal fractionation of poly(propylene-co-ethylene)

The effect of the gamma-form crystal on the thermal fractionation of a commercial poly(propylene-co-ethylene) (PPE) has been studied by differential scanning calorimetry (DSC) and wide-angle X-ray diffraction (WAXD) techniques. Two thermal fractionation techniques, stepwise isothermal crystallization (SIC) and successive self-nucleation and annealing (SSA), have been used to characterize the molecular heterogeneity of the PPE. The results indicate that the SSA technique possesses a stronger fractionation ability than that of the SIC technique. The heating scan of the SSA fractionated sample exhibits 12 endothermic peaks, whereas the scan of the SIC fractionated sample only shows eight melting peaks. The WAXD observations of the fractionated PPE samples prove that the content of the gamma-form crystals formed during the thermal treatment of the SIC technique is much higher than that of the SSA treatment. The former is 57.4%, whereas the later is 12.6%. The effect of they-form crystals on thermal fractionation ability is discussed.

FTIR study of poly(propylene carbonate)/bisphenol A blends

A systematic investigation by FTIR spectroscopy was undertaken on blends of poly(propylene carbonate) (PPC) and bisphenol A (BPA). It provided direct evidence of the hydrogen bond (H-bond) between BPA O-H groups and PPC C=O groups. Using a curve-fitting method, qualitative as well as quantitative information concerning this H-bond interaction was obtained. The inter-H-bond in PPC/BPA blends was weaker than the self-H-bond in BPA. The absorptivities of the free and the H-bonded C=O groups were nearly equal. The fraction of H-bonded C=O in the blends increased with BPA content and leveled off at a value close to 40%. Finally, FTIR-temperature measurements of pure PPC and a representative blend were reported: by monitoring the peak areas of C=O absorptions, the dissociation of the inter-H-bonds and the thermal degradation of PPC were observed. It revealed that the presence of BPA clearly retarded the thermal degradation of PPC.

Effect of poly(propylene carbonate) on the crystallization and melting behavior of poly(beta-hydroxybutyrate-co-beta-hydroxyvalerate)

The crystallization and melting behavior of poly(beta-hydroxybutyrate-co-beta-hydroxyvalerate) (PHBV) and a 30/70 (w/w) PHBV/poly(propylene carbonate) (PPC) blend was investigated with differential scanning calorimetry (DSC) and Fourier transform infrared (FTIR). The transesterification reaction between PHBV and PPC was detected in the melt-blending process. The interaction between the two macromolecules was confirmed by means of FTIR analysis. During the crystallization process from the melt, the crystallization temperature of the PHBV/PPC blend decreased about 8 degreesC, the melting temperature was depressed by 4 degreesC, and the degree of crystallinity of PHBV in the blend decreased about 9.4%; this was calculated through a comparison of the DSC heating traces for the blend and pure PHBV. These results indicated that imperfect crystals of formed, crystallization was inhibited, and the crystallization ability of PHBV was weakened in the blend. The equilibrium melting temperatures of PHBV and the 30/70 PHBV/PPC blend isothermally crystallized were 187.1 and 179 degreesC, respectively.

Crosslinkable poly(propylene carbonate): High-yield synthesis and performance improvement

A crosslinking strategy was used to improve the thermal and mechanical performance of poly(propylene carbonate) (PPC): PPC bearing a small moiety of pendant C=C groups was synthesized by the terpolymerization of allyl glycidyl ether (AGE), propylene oxide (PO), and carbon dioxide (CO2). Almost no yield loss was found in comparison with that of the PO and CO2 copolymer when the concentration of AGE units in the terpolymer was less than 5 mol %. Once subjected to UV-radiation crosslinking, the crosslinked PPC film showed an elastic modulus 1 order of magnitude higher than that of the uncrosslinked one. Moreover, crosslinked PPC showed hot-set elongation at 65 degrees C of 17.2% and permanent deformation approaching 0, whereas they were 35.3 and 17.2% for uncrosslinked PPC, respectively. Therefore, the PPC application window was enlarged to a higher temperature zone by the crosslinking strategy.

Double propagation based on diepoxide, a facile route to high molecular weight poly(propylene carbonate)

Poly(propylene carbonate) (PPC) with number average molecular weight (M-n) higher than 200 kg/mol was prepared via the terpolymerization of carbon dioxide, propylene oxide and diepoxide using Y(CCl3OO)(3)-ZnEt2-glycerine coordination catalyst. When equimolar ZnEt2 and diepoxide were used, double propagation active species were generated in situ by nucleophilic attack of metal alkoxide on diepoxide, leading to PPC of doubled M-n value. The molecular weight of PPC has dramatic influence on its thermal and mechanical performances. PPC with M of 227 kg/mol showed modulus of 6900 MPa, while the modulus of PPC with M-n of 109 kg/mol was only 4300 MPa. Moreover, when M-n increased from 109 to 227 kg/mol, a 37 degrees C increase of the onset degradation temperature was observed.

Thermotropic liquid crystallinity, thermal decomposition behavior, and aggregated structure of poly(propylene carbonate)/ethyl cellulose blends

Maleic anhydride end capped poly(propylene carbonate) (PPC-MA) was blended with ethyl cellulose (EC) by casting from dichloromethane solutions. The thermotropic liquid crystallinity, thermal decomposition behavior, and aggregated structure were investigated by differential scanning calorimetry (DSC), thermogravimetry (TGA), and wide angle X-ray diffraction (WAXD). DSC exhibits thermotropic liquid crystallinity in the rich EC composition range. TGA shows that thermal decomposition temperatures were elevated upon interfusing EC into PPC-MA. WAXD corroborates that EC and PPC-MA/EC blend films cast from dilute dichloromethane solution possessed cholesteric liquid crystalline structure in the rich EC composition range, and that dilution of PPC-MA with EC increased the dimension of noncrystalline region, leading to a more ordered packed structure.