A number of studies were conducted to demonstrate C-H activation for the construction of C-B bonds. Investigations revealed that the conversion of C-H bonds to C-B bonds was both thermodynamically and kinetically favorable. The reaction at a primary C-H bond of methane or a higher alkene B 2(OR)4 formed an alkylboronate ester R' -B(OR)2 and the accompanying borane H-B(OR2. The ester and the borane were formed on the basis of calculated bond energies for methylboronates and dioaborolanes. The rates of key steps along the reaction pathway for the conversion of a C-H bond in an alkane or arene to the C-B bond in an alkyl or arylboronate ester were favorable. These studies also highlighted the accessible barriers for C-H bond cleavage and B-C bond formation during the borylation of alkanes and arenes.

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C−H Activation for the Construction of C−B Bonds

Environmentally beneficial composites can be made by replacing glass fibres with various types of cellulose fibres. Fibres from pine or eucalyptus wood and also one-year crops such as coir, sisal, etc. are all good candidates. The poor resistance towards water absorption is one of the drawbacks of natural fibres/polypropylene composites. New natural fibres/polypropylene composites were made and the water absorption in them was studied by immersion of the composites in water at three different temperatures, 23, 50 and 70 °C. The process of absorption of water was found to follow the kinetics and mechanisms described by Fick's theory. In addition, the diffusivity coefficient was dependent on the temperature as estimated by means of Arrhenius law. A decrease in tensile properties of the composites was demonstrated, showing a great loss in mechanical properties of the water-saturated samples compared to the dry samples. The morphology change was monitored by scanning electron microscopy studies of the samples before and after exposure to water and the devastating effect of water on the fibre structure was shown.

Comparison of water absorption in natural cellulosic fibres from wood and one-year crops in polypropylene composites and its influence on their mechanical properties

Optimization Techniques with FORTRAN

Crystallization kinetics and nucleation activity of filler in polypropylene/surface-treated SiO2 nanocomposites

Effect of in situ prepared silica nano-particles on non-isothermal crystallization of polypropylene

Melt compounding was employed to prepare polypropylene (PP)/ethylene-octene copolymer (POE)/organic-montmorillonite (OMMT) nanocomposites. Polypropylene grafted with maleic anhydride (MPP) was added as a compatibilising agent. Analyses by wide-angle X-ray diffraction, transmission electron microscopy and scanning electron microscopy indicated that polymer chains intercalated into OMMT and that some of the OMMT delaminated into nano-layers dispersed in the PP matrix. Mechanical tests showed that the addition of POE increases the toughness of PP, but it decreases the stiffness. When OMMT and MPP were added, the toughness of PP increased greatly and the stiffness was not changed profoundly. Differential scanning calorimetry was used to study the melt and crystallization behavior of the composites. The nesults indicate that OMMT and MPP act as effective nucleating agents.

Polypropylene/ethylene-octene copolymer/organic-montmorillonite nanocomposites

Poly(vinyl chloride) (PVC) slush powder has been widely used; we prepared it by dry blending. We found that the absorption of plasticizer by the PVC resins was the most important factor in the dry-blending process and, further, that different types of PVC resin had different absorption rates. This results of this study provide new information about the relationship of absorption to PVC and other parameters. Haake rheomix testing and the quantity of plasticizers absorbed by the PVC resins were used to characterize the absorption process. Suspension-polymerization poly(vinyl chloride) (SPVC) and mass-polymerization poly(vinyl chloride) (MPVC) in different sizes were used for the test. The results showed that the MPVC absorbed the plasticizer more quickly than SPVC, especially at a higher temperature. However, for the same PVC resin type, the absorbing speeds were nearly independent of particle size. The studies that used a scanning electric microscope and specific surface area revealed that the morphology of the two types of particles was different. The surfaces of the individual particles of SPVC were smoother than those of MPVC. There was a “skin” covering the SPVC particles, whereas with the MPVC particles, the primary polymer was exposed directly on the surface. This difference in morphology was shown to be a significant factor in the different rates of absorption of the plasticizers for the different PVC resins. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 2369–2374, 2004

Absorption of trioctyl trimellitate into mass‐polymerization and suspension‐polymerization poly(vinyl chloride)

The present invention discloses an agitated-spouted fluidized bed which has an agitated-spouted structure, and use in preparing fibre reinforced composite thereof The fibres are mixed thoroughly with polymer powders by fluidization and agitation at the present of air as fluidizing medium in the fluidized bed, and dispersed into monofilament having absorbed polymer powders The present invention has the following advantages: immersing thoroughly between monofilament and polymer powders; simple process; less equipment investment; low energy consumption; no contamination and mass production-scale and the like After the fibre reinforced composite is pressed into GMT sheet, the GMT sheet is excellent in mechanical property

Agitated-spouted fluidized bed and use in preparing fibre reinforced composite thereof

Polymer coatings were obtained by using two rubbers, cis-polybutadiene rubber and ethylene-propylene diene monomer and two block copolymer: polystyrene-block-polybutadiene-block-polyvinyltriethoxysilane and polystyrene -block-polyvinyltrietho xysilane. They were used to coat glass fibre surfaces. The effects of the coatings on the interfacial adhesion and thermal cycling resistance of composites were studied by a single-filament fragmentation technique designed to measure the interfacial sear strength of glass fibre reinforced polypropylene. The interfacial shear strength was improved by the rubber coatings, which could graft to silane coupling agents coated onto the fibre surfaces, and could undergo crosslinking under peroxide initiation. The interfacial bond strength was determined by the nature and thickness of the rubber coatings. The interfacial adhesion was also improved when using block copolymers to treat glass fibres. The rubbers and those copolymers having flexible blocks in their chain structures both produced coatings that could relieve the thermal stresses at the composite interface duringtemperature cycling. The interface between the composites and the flexible polymer coatings had good thermal cycling fatigue resistance.

Effect of flexible polymer coating on interfacial adhesion of glass fibre reinforced polypropylene

Lightweight reinforced thermoplastics (LWRT) have a low density and high rigidity. The application of LWRTs to automotive interiors, such as headliners and instrument panels, is very promising. The porous structure of LWRTs is formed in the process of deconsolidation, so pores may appear between the matrix and fibers that interrupt the transfer of stress and deteriorate the mechanical properties. In this article, maleic anhydride-grafted polypropylene (PP-g-MAH) and glycidyl methacrylate-grafted polypropylene were selected to study the influence of compatibilizers on the structural and mechanical properties of an LWRT. It was found that the modification effect of PP-g-MAH is more significant. Before the mass fraction of PP-g-MAH reaches 20%, the tensile and flexural properties of the LWRT increased with the PP-g-MAH content. The required content of PP-g-MAH in the LWRT is high compared with the voidless composites. Structures with a good matrix distribution and dispersion are anticipated in LWRTs, which are not considered in voidless composites. POLYM. COMPOS., 2016. © 2016 Society of Plastics Engineers

Gance Dai

Papers

Polypropylene/ethylene-octene copolymer/organic-montmorillonite nanocomposites

Absorption of trioctyl trimellitate into mass‐polymerization and suspension‐polymerization poly(vinyl chloride)

Agitated-spouted fluidized bed and use in preparing fibre reinforced composite thereof

Effect of flexible polymer coating on interfacial adhesion of glass fibre reinforced polypropylene

The influence of compatibilizers on the structure and mechanical properties of lightweight reinforced thermoplastics