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Realization of structural manipulation in stereocomplex (sc) polylactic acid holds the key to fully leverage its surpassing performance, such as heat resistance and mechanical properties. In this study, we investigated the evolution of crystalline morphology/structure of equimolar racemic blends under the quantitative shear field modulated by the pulling speed of glass fiber (GF). Shear-induced crystallization...
Combined effects of shear flow and non-isothermal processing, which were akin to the practical industrial processing, on the crystallization of metallocene-made isotactic polypropylene (m-iPP) were investigated by in-situ synchrotron wide-angle X-ray diffraction (WAXD) and small-angle X-ray scattering (SAXS) techniques. The simultaneous appearance of α- and γ-crystals was observed in quiescent samples,...
A unique oscillation shear injection molding was utilized to investigate the crystallization of poly (l-lactide) (PLLA) under the coexistence of an intense shear flow and nucleating agents. The crystalline morphology and its distribution of injection-molded PLLA were probed by wide-angle X-ray diffraction, showing that an intense shear flow promotes the crystallization significantly, whereas the nucleation...
We have explored the synthesis of semi-crystalline polyamide (PA) thermosets via a reactive PA oligomer precursor route. Poly(decamethylene terephthalamide) (PA 10T) oligomers with a target Mn of 1 K and 3 K g·mol−1 were synthesized via solution polymerization and end-capped with reactive phenylethynyl (PE) groups. The reactive oligomers could be cured in a stepwise manner using successive high temperature...
Stereocomplex (sc) crystallization is appealing to endow the poly(l-lactic acid)/poly(d-lactic acid) (PLLA/PDLA) blends with superior heat resistance. However, sc formation is dampened in the high-molecular-weight (HMW) racemic blends. Here, we disclosed a simple but effective approach to facilitate sc formation by introducing carbon nanotubes (CNTs) during the solution casting. As revealed by wide-angle...
Radiation cross-linking and re-melting extensively used to decrease the wear of ultrahigh molecular weight polyethylene (UHMWPE) deteriorated the mechanical performance undesirably. This study aimed at simultaneously enhancing wear resistance and mechanical performance of UHMWPE bearings by cross-linking of the UHMPWE before melt processing followed by structural manipulation. Wear rate decreased...
To make large scale, effective use of atactic polypropylene (aPP), normally regarded as industry waste, isotactic polypropylene (iPP) was blended with aPP with a guiding ideology of “structuring processing”. Herein, the aPP/iPP blends were melt processed through modified injection molding, i.e., oscillation shear injection molding (OSIM), in which an oscillation shear flow field was applied to induce...
A kind of fluorinated and epoxy-terminated low-molecular-weight bisphenol A polycarbonate (FBPA-PC EP) was synthesized by solution polymerization of 4, 4′-(hexafluoro-isopropylidene) diphenol (6F-BPA) with triphosgene (BTC) and further reacted with epoxy chloropropane. The structure of the polymer was confirmed by FTIR, 1H NMR, 13C NMR and 19F NMR spectra. A series of negative-type fluorinated photoresists...
The polymorphic γ poly(vinylidene fluoride) (PVDF) induced by an ionic surfactant, cetyltrimethyl ammonium bromide (CTAB), is studied by using time-resolved Fourier transform infrared (FTIR) and two-dimensional (2D) correlation analysis. It is found that an extremely low content of CTAB can effectively induce γ PVDF due to the existence of strong ion-dipole interactions. Five stages are identified...
Effects of surface functionalization of carbon nanotubes (CNTs) on their nucleation ability for poly(l-lactide acid) during isothermal and nonisothermal crystallization were investigated. The results showed that the surface functional groups reduced the nucleation ability of CNTs. The polarity of the functional CNTs was notably changed due to the presence of covalent groups (i.e., –OH, –COOH, and...
The deformation behaviors of three types of polyethylene (PE) with different molecular weights and short chain branch contents were studied by in-situ Fourier transformation infrared microspectroscopic imaging (FTIRI) with a Focal Plane Array (FPA) detector during uniaxial tensile test. The crystal orientation distributions within a 250 × 250 μm 2 region during tensile test were obtained,...
By utilizing electrospun blend fibers of polystyrene (PS) and poly(ethylene oxide) (PEO) with diameters in sub-microns, nanodroplets of the minor component (PEO) were obtained by annealing the blend fibers above the glass transition temperature (T g ) of the matrix polymer (PS), as a result of the Rayleigh-Plateau instability in the melt. However, direct thermal annealing of the PS/PEO blend...
The formation of vesicles in a binary blend of an amphiphilic diblock copolymer AB/homopolymer C was studied in a dilute solution using the real space two-dimensional self-consistent field theory (SCFT). Special attention was played to the role played by the homopolymer C in controlling the vesicle formation. In the simulations, it was found that as the averaged volume fraction of homopolymer C was...
The present article reports the nonisothermal crystallization process and morphological evolution of oriented iPP melt with and without in situ poly(ethylene terephthalate) (PET) microfibrils. The bars of neat iPP and PET/iPP microfibrillar blend were fabricated by shear controlled orientation injection molding (SCORIM), which exhibit the oriented crystalline structure (shish–kebab), especially in...
The geometries and electronic properties of five novel co-polymers which are obtained by replacing phenylene ring in poly(p-phenylenevinylene) (PPV) with five different fused heterocycles, as well as their corresponding monomers and co-oligomers, have been studied using DFT method. The dihedral angle, bond length, bond-length alternation, electron density at bond critical points (BCPs), nucleus-independent...
The crystalline morphology of poly(phenylene sulfide) (PPS) isothermally crystallized from the melt under shear has been observed by polarized optical microscope (POM) equipped with a CSS450 hot-stage. The shish–kebab-like fibrillar crystal structure is formed at a higher shear rate or for a longer shear time, which is ascribed to the tight aggregation of numerous oriented nuclei in the direction...
Carbon black (CB) filled electrically conductive in situ microfibrillar poly(ethylene terephthalate) (PET)/polyethylene (PE) composites (FCMC) with CB particles selectively localizing at the surfaces of PET microfibrils were successfully prepared through a slit die extrusion–hot stretch–quenching process. Resistivity–temperature behaviors of the FCMC samples were studied systematically during heating–cooling...
The nonclassical thiophenes have received a great deal of attention because of their unusual electronic structure in several decades. Based on DFT approach, the structural and electronic properties of thieno[3,4-c][1,2,5]thiadiazole, as well as of its co-oligomers and copolymers with benzene and thiophene, are investigated theoretically. The changes of nucleus-independent chemical shifts (NICSs) as...
The poly(ethylene terephthalate) (PET)/isotactic polypropylene (iPP) in situ microfibrillar blends have been prepared through a “slit die extrusion–hot stretch–quenching” process, in which PET assumes microfibrils with 0.5–15μm in diameter depending on the hot stretching ratios (HSR, the area of the transverse section of the die to the area of the transverse section of the extrudate). The injection...
In the present study, it was attempted to fabricate a new conductive carbon black (CB) filled poly(ethylene terephthalate) (PET)/polyethylene (PE) in situ microfibrillar composite with a lower percolation threshold through selectively localizing CB particles in the surfaces of the PET microfibrils. The CB particles were first mixed with PE matrix, and then PET was added into CB/PE compound. Subsequently,...
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