John Christopher Plummer

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A method for preparing and observing clay platelets for size and shape analysis using scanning electron microscopy (SEM) was developed. Samples of the clay platelets were prepared by polyelectrolyte-assisted adsorption onto a pyrolytic graphite surface. The use of graphite as a substrate was advantageous because of the low number of secondary electrons emitted from it during imaging by SEM. The resulting low background noise allowed the emission from the 1 nm thick clay sheets to be clearly visualized. Ima

Although addition of montmorillonite (MMT) clay to isotactic polypropylene (iPP) results in large increases in the melt viscosity at low shear rates, satisfactory impregnation of glass mats is obtained with iPP/MMT under conditions typical of industrial pr ...

The dynamic shear-thickening behavior of concentrated colloidal suspensions of fumed silica in polypropylene glycol has been investigated. Dynamic frequency sweeps showed that, for any given solids concentration, the complex viscosity at different imposed ...

Desorption isotherms for water, ethanol, ethyl acetate and toluene from a sodium smectite clay have been determined by both dynamic vapor sorption (DVS) measurements and Knudsen thermogravimetry (KTGA), at the exception of toluene that was measured only by ...

This paper examines the mechanisms by which a polymer is dispersed in a co-rotating twin-screw extruder. An experimental investigation of the morphological evolution has been carried out on a 45-mm co-rotating twin-screw extruder. Polyethylene/polystyrene (PE/PS) blends in the low concentration range (i.e., 5-15 wt% of PE) were used as a model system. The following general trends were observed. First, the minor phase right after melting is predominantly in a fibrillar form. Secondly, droplet and fiber diame

The fusion bonding of neat polypropylene (PP) has been investigated under non-isothermal conditions with different initial adherend temperatures, and the results compared with results from bonds prepared under isothermal conditions with identical adherend temperatures. The mode I critical strain energy release rate of the bonds, Gc, was measured using a double cantilever beam geometry with a constant crack opening displacement. The effect of the adherend temperature and the hold time are summarized in time-

The fracture behavior of composite rubber particle-toughened polymethylmethacrylate has been investigated over a wide range of test speeds, encompassing impact conditions. When the entanglement density of the matrix was increased and its glass transition t ...

Photodegradation of wood leads to discolouration and delignification, inducing damage to the cellular structure. This study is an investigation of the damage and loss of tensile strength of the cellulose fibres in spruce (Picea abies). Microtensile tests i ...

The classical method of toughening polymethylmethacrylate (PMMA) is to incorporate composite rubber particles into the homopolymer matrix. This approach has been extended in the present work by (i) combining rubber toughening with chemical modification of ...

As part of a broader effort to establish processing-structure-property relationships in PLLA/nHA, which is currently under consideration for bioresorbable scaffolds for bone repair, hot stage optical microscopy and differential scanning calorimetry have be ...

The equilibrium rheological properties of a range of isotropic exfoliated and intercalated hyperbranched polymer (HBP)/montmorillonite (MMT) clay nanocomposites have been investigated using low strain oscillating shear measurements at temperatures above the glass transition temperature of the HBP. Predominantly exfoliated nanocomposites showed a sharp increase in shear viscosity at about 0.8 wt % MMT, associated with a transition from Newtonian to solid-like behavior, which was characterized in terms of a l

The influence of cure temperature, composition and chemical structure on the morphology resulting from chemically induced phase separation has been investigated for different epoxy functionalized dendritic hyperbranched polymers blended with diglycydil bisphenol A and an aliphatic diamine. The cure temperature window chosen highlighted the influence of both the kinetics of phase separation and the thermodynamics of mixing on the final morphology. In relatively immiscible blends and at low cure temperatures,

This work compares the time dependence of isothermal shape recovery in thermoset and thermoplastic shape memory polyurethanes (SMPUs) with comparable glass transition temperatures. In each case, tensile tests have been used to quantify the influence of var ...

The strength of fusion bonds between polyamide 12 plaques has been investigated as a function of processing conditions, using the double cantilever beam geometry to measure the mode I critical strain energy release rate, GC. Bonding was carried out using an instrumented press, which allowed systematic variation of the bonding time, the holding pressure, the interface temperature and the initial difference in temperature between the plaques. GC was generally found to increase with hold time and interface tem

The invention relates to a polyamide material containing a polyamide as the matrix polyamide and fibrillar polyamide particles, wherein at least 10 vol.% of the fibrillar polyamide particles, based on the total volume of the fibrillar polyamide particles, ...

The invention describes a composition containing a) a functionalized polymer (10) that comprises at least one polymer segment (13) and at least two polymer aggregating segments (11,12) capable of forming non-covalent bonds based on a supramolecular interac ...

Benzenetricarboxamide (BTA) derivatives are versatile compounds widely employed as nucleating agents in commercial semicrystalline plastics and as supramolecular ligands in self-assembling telechelic polymer-based organogels, hydrogels, and bulk elastomers ...

The aim of this work is to integrate polypropylene/montmorillonite (MMT) nanocomposite matrices into conventional fibre-reinforced composites. Two types of composite have been considered: long fibre-reinforced composites from co-woven glass fibre and nanoc ...

Two to four pseudo-generation aliphatic hyperbranched polymers (HBPs) with OH end-groups have been solution processed with various types of montmorillonite (MMT) layered alumino-silicate clays, and carefully dried to produce solid HBP/MMT nanocomposites. Exfoliated nanocomposites were obtained by processing the polyester HBPs with up to 20 wt% Naþ MMT in water, and intercalation only became dominant at higher loadings, for which the MMT layer spacing was directly dependent on the HBP pseudo-generation numb

Semiaromatic polyamides are used for metal replacementin advancedengineering applications to reduce weight and improve efficiency,but their range of application is limited by their inherent lack ofductility and toughness. Here, we combined semiaromatic pol ...

John Christopher Plummer

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Practical method for high-resolution imaging of polymers by low-voltage scanning electron microsopy

Hybrid glass mat reinforced polypropylene-montmorillonite nanocomposites

Pre- and Post-Transition Behavior of Shear Thickening Fluids in oscillating Shear

Equilibrium desorption isotherms of water, ethanol, ethyl acetate and toluene on a sodium smectite clay

Characterization of Hyperbranched Aliphatic Polyesters and their Trimethylsilylated Derivatives by GPC-Viscometry

Non-isothermal fusion bonding of polypropylene

The Influence of Matrix Modification on Fracture Mechanisms in Rubber Toughened Polymethylmethacrylate

Loss of tensile strength in cellulose tissue on the surface of spruce (Picea abies) caused by natural photodegradation and delignification

Microdeformation mechanisms in rubber toughened PMMA and PMMA-based copolymers

Solidification behavior of PLLA/nHA nanocomposites

Rheological behavior of hyperbranched polymer/montmorillonite clay nanocomposites

Morphology build-up in dendritic hyperbranched polymer modified epoxy resins: Modelling and characterisation

Isothermal recovery rates in shape memory polyurethanes

Fusion bonding of polyamide 12

Polyamide material

Composition containing a polymer and an additive

Polymer-bridged Nanofibrils in a High-molar-mass Polyester via Co-assembly of Benzenetricarboxamide End Groups and an Additive

Processing of Hybrid Glass-Fibre Reinforced Thermoplastic Nanocomposites

Hyperbranched Polymer/Montmorillonite Clay Nanocomposites

Thermoplastic Toughening of a Semiaromatic Polyamide with an Amino-telechelic Polyethylene