Characterization of the Microstructure of Bimodal HDPE Resin

In this work, two industrial bimodal high density polyethylene resins, resin A and resin B having similar molecular weight (M-w), molecular weight distribution (M-wD), and short-chain branching (SCB) content but different mechanical properties, were fractionated through cross-fractionation. The fractions were further, characterized by GPC, C-13 NMR, DSC AND FT IR techniques. These two resins were firstly fractionated into two franctions, i.e. high-temperature and low temperature fractions, via preparative solution crystallization fractionation. Resin A with much better mechanical properties contains more high-temperature fractions with longer crystalizable sequences. The SCB content in the low temperature fraction of resin A is lower than the of resin B. Both low-temperature fractions were then further fractionated using solvent gradient fractionation (SGF). The characterization of SGF fraction indicates that most of the branches fall into the high molecular weight chain in both low-temperature fractions.

Micropatterning of polymeric semiconductor by selective lift-off method using epoxy mold

A simple and efficient method for patterning polymeric semiconductors for applications in the field of organic electronics is proposed. The entire polymer layer, except for the desired pattern, is selectively lifted off from a flat poly(dimethylsiloxane) (PDMS) stamp surface by an epoxy mold with a relief pattern. This is advantageous because the elastic deformation of the PDMS stamp around protrusions of a patterned stamp under pressure can assist the plastic deformation of a polymer film along the pattern edges, yielding large area and high quality patterns, and the PDMS surface has low surface energy, which allows the easy removal of the polymer film.

Micropatterning of metal films coated on polymer surfaces with epoxy mold and its application to organic field effect transistor fabrication

In this letter, a simple and versatile approach to micropatterning a metal film, which is evaporated on a Si substrate coated with polymer, is demonstrated by the use of a prepatterned epoxy mold. The polymer interlayer between the metal and the Si substrate is found important for the high quality pattern. When the metal-polymer-Si sandwich structure is heated with the temperature below T-m but above T-g of the polymer, the plastic deformation of the polymer film occurs under sufficiently high pressure applied. It causes the metal to crack locally or weaken along the pattern edges. Further heating while applying a lower pressure results in the formation of an intimate junction between the epoxy stamp and the metal film. Under these conditions the epoxy cures further, ensuring adhesion between the stamp and the film. The lift-off process works because the adhesion between the epoxy and the metal film is stronger than that between the metal film and the polymer. A polymer field effect transistor is fabricated in order to demonstrate potential applications of this micropatterning approach.

Adsorption of heavy rare earth(III) with extraction resin containing bis(2,4,4-trimethylpentyl) monothiophosphinic acid

In the present paper, the adsorption of thulium(Ill) from chloride medium on an extraction resin containing bis(2,4,4-trimethylpentyl) monothiophosphinic acid (CL302, HL) has been studied. The results show that 1.5 h is enough for the adsorption equilibrium. The distribution coefficients are determined as a function of the acidity of the aqueous phase and the data are analyzed both graphically and numerically. The plots of log D versus pH give a straight line with a slope of about 3, indicating that 3 protons are released in the adsorption reaction of thulium(III). The content of Cyanex302 in the resin is determined to be 48.21%. The total amount of Tm3+ adsorbed up to resin saturation is determined to be 82.46 mg Tm3+/g resin. Therefore, the sorption reactions of Tm3+ from chloride medium with CL302 can be described as: Tm3+ + 3HL((r)) <----> TmL3(r) + 3H(+) The Freundlich's isothermal adsorption equation is also determined as: log Q = 0.73 log C + 3.05 The amounts (Q) of Tm3+ adsorbed with the resin have been studied at different temperatures (15-40degreesC) at fixed concentrations of Tm3+, amounts of extraction resin, ion strength and acidities in the aqueous phase.

Stable multilayer films based on photoinduced interaction between polyoxometalates and diazo resin

Ultrathin multilayers films consisting of Keggin anion [PMo12O40](3-) and diazo resin were first prepared by the electrostatic layer-by-layer self-assembly method. This film material could be stabilized by the photoinduced interaction between Keggin anion and diazo resin. IR spectra and X-ray photoelectron spectra revealed the occurrence of the partial transformation from ionic bond to covalent bond between layers of the film under irradiation by UV light. Such transformation increases the stability of the film, which was demonstrated by AFM images and the etching experiments with organic solvent.

Mesoscopic simulation of the impregnating process of unidirectional fibrous preform in resin transfer molding

The resin transfer molding has gained popularity in the preparation of fiber-reinforced polymer-matrix composites because of its high efficiency and low pollution. The non-uniform inter-tow and intra-tow flows are regarded as the reason of void formation in RTM. According to the process characteristics, the axisymmetric model was developed to study the interaction between the flow in the inter-tow space and that in the intra-tow space. The flow behavior inside the fiber tows was formulated using Brinkman's equation, while that in the open space around the fiber tows was formulated by Stokes' equation. The volume of fluid (VOF) method was applied to track the flow front, and the effects of filling velocity, resin viscosity, inter-tow dimension and intra-tow permeability on fluid pressure and flow front were analyzed. The results show that the flow front difference between the inter-tow and intra-tow becomes larger with the decrease of intra-tow permeability, as well as the increase of filling velocity and inter-tow dimension.

Lanthanide complex/polymer composite optical resin with intense narrow band emission, high transparency and good mechanical performance

Novel composite resins possessing good luminescent properties have been synthesized through a free radical copolymerization of styrene, alpha-methylacrylic acid and the binary or ternary complexes of lanthanide ions (Eu3+ and Tb3+). These polymer-based composite resins not only possess good transparency and mechanical performance but also exhibit an intense narrow band emission of lanthanide complexes under UV excitation. We characterized the molecular structure, physical and mechanical performance, and luminescent properties of the composite resins. Spectra investigations indicate that alpha-methyl-acrylic acid act as both solubilizer and ligand. Photoluminescence measurements indicate that the lanthanide complexes show superior emission lines and higher intensities in the resin matrix than in the corresponding pure complex powders, which can be attributed to the restriction of molecular motion of complexes by the polymer chain networks and the exclusion of water molecules from the complex. We also found that the luminescence intensity decreased with increasing content of alpha-methylacrylic acid in the copolymer system. The lifetime of the lanthanide complexes also lengthened when they were incorporated in the polymer matrix. In addition, we found that the relationships between emission intensity and Tb (Eu) content exhibit some extent of concentration quenching.