Synthesis of Polyurethane Acrylate and Application to Ultraviolet-Curable Pressure-Sensitive Adhesive

Synthesis of polyurethane acrylates (PUA) using dimer acid-based polyester diol and hydrogenated castor oil (HCO) and preparations of the UV-curable pressure-sensitive adhesive (PSA) were reported. The effect of hydroxyl from dimer acid polyester diol/hydroxyl from HCO ratio (OH_Diol/OH_HCO), hydroxyl from both HCO and DAPD/2-hydroxyethyl acrylate ratio (OH_Polyol/_HEA), and tackifying resin/PUA ratio on the dynamic viscoelastic properties and performance of UV-cured PSA were investigated. The study revealed that, with OH_Diol/OH_HCO and OH_Polyol/_HEA increased, the storage modulus (G′), the loss modulus (G″), and complex viscosity (Eta?) of UV-cured PSA increased, and so did the corresponding holding power (HP). Peeling strength, however, decreased. As increasing the tackifying resin/PUA ratio, G′, G″ and Eta? decreased, and so did HP, whereas the peeling strength increased. Catalysts affected the dynamic properties and the performance of PSA. In contrast with PSA corresponding to dibutyltin dilaurate (DBTDL), the PSA corresponding to organic bismuth (OB) had higher dynamic modulus, complex viscosity, and holding power, but lower peeling strength.     

Preparation and Characterization of Conductive Polypyrrole/Organophilic Montorillonite Nanocomposite

Polyvinylpyrrolidone (PVP) was used as organic intercalative modifier to prepare organophilic montorillonite OMMT-P. PPy/OMMT nanocomposites were prepared by the oxidative polymerization of pyrrole (Py) intercalated into the interlayer of OMMT. The effect of Py, OMMT, oxidant, and dopant content on nanocomposites' conductivity were studied, and the conductivity of PPy/OMMT-P was achieved as high as 15.0 S·cm^?1 when the molar ratio of FeCl₃ and Py is 2.50, the mass ratio of Py and OMMT-P is 0.25, and the TSANa concentration is 0.025 g·ml^?1. The structure and properties of the nanocomposites are characterized with FT-IR, TG, and XRD.     

Electrically Conductive Carbon Black/Poly(Ethylene Terephthalate)/Polyethylene Microfibrillar Composite: The influence of CaCO3 Nanoparticles

The influence of a complex filler system on the electrical properties of a microfibrillar conductive polymer composite (MCPC) is discussed. By adding insulating filler, nano-CaCO₃, to carbon black (CB)-filled MCPC, the morphology of the poly(ethylene terephthalate) (PET) microfibrillar phase was tailored according to the ratio of CB/nano-CaCO₃, and so were the electrical properties of MCPC. It was found that nano-CaCO₃ did not influence electrical properties in a monotone way. With an increase in nano-CaCO₃ content, on one hand, the surface of the microfibrils became smoother, which jeopardized the conductivity of the MCPC. At the same time, the nano-CaCO₃ particles substituted for the CB particles on the surface of the microfibrils and further decreased conductivity. On the other hand, longer and better-defined microfibrils could form, which enhanced the conductive network and increased the conductivity of the MCPC. As a result, the percolation threshold changed little compared to the common CB-filled MCPC.     

Comparison on the Properties of Nickel-Coated Graphite (NCG) and Graphite Particles as Conductive Fillers in Polypropylene (PP) Composites

The present study was carried out to evaluate the performance of nickel-coated graphite (NCG) in comparison with graphite as conductive fillers in polypropylene (PP) matrix. Graphite exhibits smaller particle size and higher aspect ratio (length/thickness) than NCG particles. The results showed that the additions of graphite filler in PP exhibits higher tensile properties and electrical conductivity compared to NCG filled PP composites. The electrical results showed that the percolation threshold of graphite and NCG filled PP composites occurred in the range of 10 to 20 vol.% and 15 to 25 vol.%, respectively.     

The effect of sintering temperature variations on the development of electrically active interfaces in zinc oxide based varistors

A series of zinc oxide based varistors containing 0.5 wt.% Bi₂O₃ and 0.5 wt.% Mn₂O₃ were prepared by a conventional mixed oxide route and sintered at temperatures between 950 and 1300°C. All samples showed the varistor effect, although as the sintering temperature was increased above 1000°C, the non-linear coefficient decreased from 22 to 3 at 1300°C. Local grain boundary property measurements were carried out using remote electron beam induced current (REBIC) configuration conductive mode scanning electron microscopy. The proportions of electrically active interfaces and those showing strong resistive contrast were found to increase with sintering temperature.     

Copper-based Conductive Polymers: A New Concept in Conductive Resins

The history of making plastic materials conductive to both electric currents and to the transfer of thermal energy has traditionally been accomplished by the addition of metallic particles into a resin matrix. Principally, such metals as aluminum, silver, gold, nickel and copper have been used. Copper has had a limited success due to its tendency to form a non-conductive oxide surface layer and currently such adhesives depend primarily on silver for high conductivity.

An intense research effort to eliminate the problems associated with copper-filled conductive polymers resulted in a treatment and preparation of copper flake that allows the stable formation of a conductive structure within a polymer matrix. Once the activated copper particles are in the resin, the formulation is stable. Most of the resins evaluated have been epoxy resins although certain thermoplastic resins have also been made conductive. Volume resistivities as low as 10^-5 ohm-cm have been achieved.     

炭黑填充型导电塑料的研究与应用现状

介绍工艺条件、基体和炭黑特性、用量等对炭黑填充型导电塑料的影响及开发与应用情况。     

导电增韧聚甲醛的制备及性能

探讨了炭黑和抗静电剂改性硅油分别使用与协同使用对聚甲醛(POM)导电性能和力学性能的影响,同时研究了增韧剂聚氨酯弹性体(TPU)对POM导电性能和力学性能的影响。结果表明:炭黑和改性硅油配合使用,可使POM的表面电阻率达到102Ω,而其力学性能也比单独使用炭黑有所改善。增韧剂TPU进一步提高了导电POM的冲击强度,但使导电POM的表面电阻率增加到106Ω。     

Study of multi-walled carbon nanotubes for lithium-ion battery electrodes

The potential use of multi-walled carbon nanotubes (MWCNTs) produced by Chemical Vapor Deposition (CVD) as conductive agent for electrodes in Li-ion batteries has been investigated. LiNi_0.33Co_0.33Mn_0.33O₂ (NCM) has been chosen as the active material for positive electrodes, and a nano-sized TiO₂-rutile for the negative electrodes. Also the MWCNTs ability of reversibly inserting Li has been characterized. The electrochemical performances of the electrodes are studied by galvanostatic techniques and cyclic voltammetry. In particular the influence of the nanotubes on the rate capability is evaluated. The addition of MWCNTs significantly enhances the rate performances of NCM-based cathodes at all investigated C-rates. The 1 wt.% MWCNTs in TiO₂ rutile-based anodes accounts for an increase in the rate capability when the electrodes are cycled in the potential range 1.0-3.0 V. The range extension to more negative potentials (i.e. 0.1-3.0 V), however, causes a capacity fading especially at higher current rates. The obtained results demonstrate that the addition of MWCNTs to the electrode composition, even in low amounts, enables an increase in both energy and power densities of a Li-ion battery.