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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...
Crystalline polymers can exhibit anomalous crystallization behaviors as restricted into nanodomains. Herein, syndiotactic polypropylene (sPP) was infiltrated into nanoporous alumina templates with different pore diameters, and their nonisothermal and isothermal crystallization kinetics were investigated. As located inside nanopores, the crystallization of sPP becomes sluggish. The crystallization...
The thermal imidization process of 1,2,4,5-benzenetetracaboxylic (PMDA)/4,4’-diamnodiphenyl ether (4,4′-ODA) solutions in N-methyl-2-pyrrolidone (NMP) from polyimide (PI) precursor, poly (amic acid) (PAA), was systematically investigated through a series of characterization methods, such as Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), differential scanning calorimetry...
Surface tethered polyelectrolyte brushes are scientifically interesting and technologically relevant to many applications, ranging from colloidal stabilization to responsive and tunable materials to lubrication. Many applications operate in environments containing multi-valent ions, media in which our scientific understanding is not yet well-developed. We synthesized high-density polystyrene sulfonate...
Hydrogenation has been proved to be an efficient way to remove the toxicity of phthalate plasticizer. However, other influences of this hydrogenation are still unknown. Here we chose di-2-ethylhexyl phthalate (DOP) and di(2-ethylhexyl) cyclohexane-1,2-dicarboxylate (DEHHP) to study the influence on interaction with poly(vinyl chloride) (PVC). By combining experiment and calculation, we found the interaction...
The plastic deformation behavior of isotactic polypropylene (iPP) film is studied with in-situ Fourier transformation infrared microspectroscopic imaging (FTIRI). During uniaxial tensile test, spatial distributions of crystallinity and orientations are obtained in necking region (NR), transition front (TF) and non-necking region (NNR). A low valley of crystallinity exists at TF, while both NNR and...
Poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) was synthesized by oxidative polymerization of 2,6-dimethylphenol (DMP) using a water-soluble copper complex catalyst under oxygen and with natural ligands in alkaline water. Arginine, guanine, adenine, cytosine, histidine, and folic acid were used as ligands for the copper complex. Arginine performed the best, with a yield of 72%, a number-average molecular...
The crystal–crystal transition of isotactic polybutene-1 (iPB-1) from form II to I at room temperature is investigated with in-situ Fourier transform infrared spectroscopy (FTIR), Fourier transformation infrared microspectroscopic imaging (FTIRI) and synchrotron radiation scanning X-ray micro-diffraction (SR-μSXRD). The transition rate from form II to I shows a non-monotonic correlation with crystallization...
Two series of benzoxazine (BOZ) based composites were prepared with graphene oxide (GO) and graphite via in situ intercalative polymerization. Based on isothermal and non-isothermal mode Differential Scanning Calorimetry results, BOZ with the addition of GO could not only decrease the cure temperature, but also increase the cure rate of BOZ. On the contrary, BOZ with the addition of graphite would...
The deformation behavior of a single spherulite embedded in quenched isotactic polypropylene (iPP) film is studied with in-situ infrared microspectroscopic imaging (FTIRI) with Focal Plane Array (FPA) detector during uniaxial tensile test. Imaging an area of 250 × 250 μm 2 with 4096 Fourier transform infrared (FTIR) spectra, the absorption distributions of crystalline (998 cm −1 band)...
A new method to obtain enzymatic rate coefficients for synthesis of biological homopolymers is presented. The new method involves fitting molecular weight distributions (MWDs) obtained by taking samples at successive times from an in vitro enzyme-catalyzed system. Enzymatic rate coefficients can then be obtained by fitting the observed MWDs to an assumed model. These types of results are complementary...
Poly(N-vinylpyrrolidone) (PVP) hydrogels have become increasingly important materials for pharmaceutical and biomedical applications. UV-light initiated oxidative crosslinking of PVP represents a novel method for producing PVP based hydrogel materials. However, the mechanism of the gelation by this approach is poorly understood. In this study, the reaction mechanism for the crosslinking process is...
We have used DSC, FTIR spectroscopy, and ac impedance techniques to investigate the interactions that occur within complexes of poly(vinylpyrrolidone-co-methyl methacrylate) (PVP-co-PMMA) and lithium perchlorate (LiClO 4 ) as well as these systems' phase behavior and ionic conductivities. The presence of MMA moieties in the PVP-co-PMMA random copolymer has an inert diluent effect that reduces...
Morphological features of isotactic polypropylene (iPP) and high impact polypropylene (hiPP) particles produced in a multistage polymerization process were investigated by field-emission electron microscopy (FESEM) and transmission electron microscopy (TEM) techniques. Study was mainly focused on architecture of iPP particle and distribution of elastomer phase (EPR) within the preformed iPP matrix...
The morphology and thermal stabilization mechanism of polymeric nanocomposites prepared by solution intercalation of linear low density polyethylene (LLDPE) with montmorillonite (MMT), MgAl layered double hydroxide (LDH), and ZnAl LDH have been studied by X-ray diffraction (XRD), transmission electron microscopy (TEM), dynamic Fourier transform infrared (FTIR) spectroscopy, and thermogravimetric analysis...
It is essential to understand the molecular level response of crosslinked cellulose chain segments upon deformation, in order to develop new agents which convey high durable-press (DP) rating to cellulose fibers with minimal strength loss. In this work models of amorphous cellulose crosslinked with both rigid and flexible crosslinks were constructed computationally for this purpose. Rigid crosslinks...
Molecular modeling was utilized to provide insight into the yielding behavior and poor recovery from applied strain for cellulose. Amorphous cellulose models were successfully built and examined with the use of force field pcff_300_1.01. High-temperature molecular dynamics, followed by minimization, was used to generate relaxed structures for amorphous cellulose. Properties related to inter-molecular...
A novel cytocompatible graft copolymer of chitosan and l-lactic acid (CL) was prepared by grafting l-lactic acid onto the amino groups in chitosan without a catalyst. The structures of the CL graft copolymers were characterized by FTIR, 13 C-NMR and X-ray measurements. Degree of substitution and side-chain length were evaluated from salicylaldehyde and elemental analysis. The tensile strength...
Both pyrene-fluorescence probe and fluorescence label techniques are used to investigate the association behaviors of hyperbranched poly(sulfone-amine) (HPSA) in aqueous solution. In the presence of HPSA, excimer emission peak evidently appeared, while no excimer peak was observed in the emission spectra in the absence of HPSA. The excitation spectrum monitored at excimer emission red shifts by about...
This work has demonstrated that the addition of an optimum content of dimethyldioctadecylammonium chloride (DDAC)-modified montmorillonite clay (Dclay) enhances the ionic conductivity of the plasticized poly(methyl methacrylate)-based electrolyte by nearly 40 times higher than the plain system. Specific interactions among silicate layer, carbonyl group (C O) and lithium cation have been investigated...
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