John Christopher Plummer

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Amphiphilic multiarm star-block copolymers with a hydrophobic inner and a hydrophilic outer shell have been used to encapsulate hydrophobic bioactive volatiles in aqueous media under realistic application conditions. The release rates of the bioactive comp ...

We recently discovered that wheat gluten could be formed into a tough, plasticlike substance when thiol-terminated, star-branched molecules are incorporated directly into the protein structure. This discovery offers the exciting possibility of developing biodegradable high-performance engineering plastics and composites from renewable resources that are competitive with their synthetic counterparts. Wheat gluten powder is available at a cost of less than dollars 0.5/lb, so if processing costs can be control

Numerical calculations of the evaporation kinetics of bulk volatile liquids and of water from smectite clay granules are compared with experimental results. The weight loss of the volatiles is analyzed by thermogravimetry and differential calorimetry. Unde ...

A waterborne latex-based technique has been used to prepare acrylic films with laponite contents up to about 25 vol%. The laponite was attached to the surfaces of the latex particles, giving a cellular arrangement of laponite-rich regions at high laponite ...

Plasticization of medical grade poly-L-lactide (PLLA) by addition of polyethylene glycol (PEG) with various molar masses has been evaluated as means of producing low stiffness matrices for bioresorbable scaffolds for soft-tissue engineering applications. A ...

Biopolymers often show deterministic chain folding templated by repeat unit sequences whose conformations are locked in by intramolecular interactions. In this work, we have used repeat units based on rigid anthracene or acridine scaffolds, which we refer ...

The influence of the primary molecular parameters chain configuration, architecture and molecular weight (MW) on the mode of mechanical breakdown is discussed for two series of (amorphous) thermoplastic polymers, methyl methacrylate glutarimide copolymers and amorphous semi-aromatic polyamides. Structural and dynamic analyses and fracture mechanical methods applied to such adequately chemically modified (glassy) polymers permit us to show and to explain the effect of intrinsic variables on local molecular m

Optical and transmission electron microscopy have been used to investigate the microdeformation mechanisms in thin films of amorphous semi-aromatic polyamides with different chemical structures and chain lengths. In the chosen range of test temperatures (between 2120 8C and the principal mechanical relaxation temperature, Ta), three successive microdeformation mechanisms were identified: chain scission crazing (CSC) at the lowest temperatures, shear deformation zones (SDZs) at intermediate temperatures and

To gain insight into the physical nature of the coupling between mechanical stress and humidity variations, the behaviour of thin wood strips was studied using specially developed apparatus for creep/recovery and relaxation/blotting-out tests in a controlled humidity environment. The load time and the rate of viscoelastic creep were found to have little influence on mechano-sorptive creep. Moreover, creep trajectory curves for specimens with continuous and interrupted humidity cycles indicated divergence fr

The control of local order in polymer semiconductors using non-covalent interactions may be used to engineer materials with interesting combinations of mechanical and optoelectronic properties. To investigate the possibility of preparing n-type polymer sem ...

Polyurethane (PU)/acrylic hybrid particles with different PU contents were synthesized by miniemulsion polymerization and subsequently dried to give solid adhesive films. The morphologies of the particles and the morphologies and mechanical properties of t ...

Amelogenin refers to a class of intrinsically disordered proteins that are the major constituents of enamel matrix derivative (EMD), an extract of porcine fetal teeth used in regenerative periodontal therapy. Modifications in molecular conformation induced ...

A waterborne latex-based technique, in which functionalized laponite is attached to PS and acrylic latex particles, is used to prepare films containing up to 50 wt% laponite. At high laponite contents this leads to a cellular arrangement of the laponite-rich layers, concentrated at the latex particle interfaces. MDSC shows that a significant proportion of the organic matrix does not contribute to the glass transition. However, this "rigid" matrix fraction arises from intercalation of the laponite stacks, an

Desorption processes of low-molecular-weight compounds from the surface of smectites into the gas phase determine a number of processes, e.g. those involved in drug delivery and the release of herbicides. The desorption has not been investigated thoroughly ...

The low frequency mechanical and dielectric behavior of three different elastomers has been investigated by dynamic mechanical analysis and dielectric spectroscopy, with the aim of accounting for the frequency dependence of the characteristics of the corre ...

All-polyamide composites containing up to 30 vol% highly dispersed PPTA nanofibrils with diameters in the range 50-500 nm were prepared by melt-compounding polyamide 6,10 (PA610) with chopped poly(p-phenylene terephthalamide) (PPTA) fibers in the temperatu ...

The aim of the present research has been to quantify the influence of different materials on the global dynamic response of a ski. The properties of the individual constituent materials were characterized as a function of temperature and frequency using dy ...

Tensile tests have been carried out over a wide range of test speeds on compact tension specimens of polyamide 6 containing spherical silica particles, whose size and content had been adjusted to give optimum impact performance in conventional impact tests after conditioning at 50% relative humidity. The tensile test results confirmed there to be a significant improvement in the high speed crack initiation resistance at room temperature and at high moisture contents on addition of the silica particles. Howe

Diffusion of CO2 in polylactide was modelled by assuming the diffusion coefficient to depend on CO2 concentration, c, according to D[c]=D[0]exp[Ac], where D[0] and A are empirical constants, with the aim of optimizing impregnation of nominally amorphous an ...

The development of the interfacial bond strength as a function of bonding conditions has been investigated in two representative semicrystalline thermoplastics, isotactic polypropylene and polyamide 12. If one side of the interface is well above the melting point immediately before contact, more rapid effective bonding is obtained for a given estimated interface temperature than under isothermal conditions. This is discussed in terms of a simple two-parameter model for the critical strain energy release rat

John Christopher Plummer

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Investigation of the Release of Bioactive Volatiles from Amphiphilic Multiarm Star-Block Copolymers by Thermogravimetry and Dynamic Headspace Analysis

Designing new materials from wheat protein

Evaporation kinetics of volatile liquids and release kinetics of water from a smectite clay: Comparison between experiments and finite element calculations

Small strain mechanical properties of latex-based acrylic nanocomposite films

Plasticization of poly-L-lactide for tissue engineering

Semiaromatic Polyamides with Re-Entrant Chain Folding Templated by "U-Turn" Repeat Units

Crazing and fracture in polymers. micromechanisms and effect of molecular variables

Microdeformation mechanisms in thin films of amorphous semi-aromatic polyamides

Transient moisture effects on wood creep

Semiaromatic polyamides with enhanced charge carrier mobility

Influence of composition on the morphology of polyurethane/acrylic latex particles and adhesive films

Molecular dynamics simulations of the intrinsically disordered protein amelogenin

Small strain mechanical properties of latex-based nanocomposite films

Kinetics Of Desorption Of Water, Ethanol, Ethyl Acetate, And Toluene From A Montmorillonite

Frequency dependent dielectric and mechanical behaviour of elastomers for actuator applications

All-polyamide nanofibrillar composites by in situ fibrillation of aramid fibers

Dynamic Properties of Materials for Alpine Skis

Fracture resistance of mineral reinforced polyamide 6

Liquid CO2 processing of solid polylactide foam precursors

Non-Isothermal Fusion Bonding in Semicrystalline Thermoplastics