John Christopher Plummer

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Copolymerizing poly(hexamethylene terephthalamide-co-isophthalamide) (PA6TI) with 40 wt% polyamide 66 (PA66) results in only minor decreases in modulus and yield stress owing to isomorphous substitution of PA6TI units by PA66 units in the PA6TI alpha phase ...

Raman microscopy is applied to a gel-spun UHMWPE-fibre (Dyneema SK60) to determine the distribution of axial molecular stresses and their change with time (in creep and during stress relaxation). A more detailed method is proposed to quantify the observed characteristic changes in local stress distribution. The increase in highly overstressed bonds (5 8 GPa) is ascribed to the straining of tie-molecules during creep. Their pull-out, crystal plasticity and grain-boundary slip determine stress relaxation. A r

Transmission electron microscopy (TEM) has been used to investigate the effect of laponite clay on microdeformation in thin latex-based polystyrene (PS) films, in which the laponite was concentrated at the original interfaces between the PS particles. At r ...

The influence of the surface morphology of semicrystalline polyamide 12 PA12! on the adhesion of thin silicon oxide coatings is analyzed by means of uniaxial fragmentation tests and scanning local-acceleration microscopy SLAM!. Two types of PA12 substrates are investigated, namely, as-received PA12, which contains large spherulites, and quenched PA12, which has a relatively smooth, homogeneous surface structure. The adhesion of the coating is found to be identical for the two types of PA12. This indicates t

The mechanical and damping properties of unidirectional (UD) and twill 2/2 flax fibre (FF) reinforced thermoset (epoxy) and thermoplastic (polypropylene (PP) and polylactic acid (PLA)) composites containing 40 vol% of fibres have been compared with those o ...

Equilibrium phase diagrams in composition-conversion space have been calculated for stoichiometric blends of an epoxy resin with a diamine hardener and dendritic hyperbranched polymers, to which various numbers of epoxy groups have been grafted. An attempt has been made to incorporate both the effects of the polydispersity of the resin and the reactivity of the functionalized hyperbranched polymers. The results suggest that below the gel point, the resin-rich regions of the phase diagrams are only weakly af

The core–shell structure of a range of acrylic–acrylic latexes has been investigated by combining different specimen preparation methods with transmission electron microscopy (TEM), dark-field scanning transmission electron microscopy (DSTEM) and low-volta ...

The present article reviews basic techniques widely used for fundamental research, as well as in the plastics and composites industries, for the characterization of polymer-based materials destined for bulk applications, such as packaging, construction, tr ...

The effects of the size (pseudo-generation number) and nature of end groups on physical and rheological properties were investigated for a series of hyperbranched polyesters based on an ethoxylated pentaerythritol core and 2,2-bis-(hydroxymethyl) propionic acid repeat units. The observed linear dependence of the melt viscosity on the molar mass in the high pseudo-generation-number limit indicated that entanglement effects were substantially absent. Moreover, the marked influence of end capping of the end gr

The thermomechanical response of a series of thermally activated shape memory polyurethanes (SMPUs), determined by dynamic mechanical analysis (DMA), has been adjusted by systematic modification of the molecular architecture. It is argued that the free rec ...

The mechanical properties of extruded films of isotactic polypropylene (iPP) and ethylene-propylene rubber toughened iPP (iPP/EPR) have been analyzed in terms of the specific essential and non-essential work of fracture using high speed tensile test apparatus modified for quasi-static testing in the range 0.0001 to 3 ms.1. Three iPP/EPR grades with modifier contents of 15, 21 and 30 vol% were investigated. As the deformation rate increased, relatively uniform necking of the whole ligament and extensive plas

A high penetration grade bitumen has been blended with up to 50 wt% of two different grades of metallocene catalyzed linear low density polyethylene (m-LLDPE) in order to investigate the potential of these and similar copolymers as a substitute for styrene ...

BA/MMA (90:10 wt.-%) were copolymerized in the presence of two different organomodified clays (C30B and CMA16) and 1.6-2.6wbm.-% surfactants. The effect of the compatibility of the organoclay in the monomer mixture on the morphology of hybrid polymer/clay particles was determined using TEM. The resulting morphologies were compared with the prediction of a Monte-Carlo simulation that determined the equilibrium morphology of monomer/clay hybrid miniemulsion droplets. The model predicted encapsulated morpholog

The present work is aimed at assessing the feasibility of integrating thermoplastic polypropylene nanocomposite matrices into conventional fiber-reinforced composites based on hybrid textiles that incorporate both the matrix and glass-fiber yarns, in order ...

Recent investigations of the tensile fracture behaviour of representative glassy and semicrystalline impact-resistant polymers are reviewed, with emphasis on the microdeformation behaviour as revealed by electron microscopy of sections from bulk specimens, where the crack-tip damage zone has been embedded and/or stained under load, and on thin films deformed in situ. The insight that such techniques have provided into the toughening mechanisms is discussed.

The morphology of polymer/nanofibrillated cellulose (NFC) composite sheets produced using different techniques and its influence on low strain stiffness were assessed by optical and transmission electron microscopy. Solvent processing led to relatively hom ...

Cast polyurethane thermosets have been modified with randomly oriented exfoliated and intercalated montmorillonite clay usinghyperbranched polymers (HBP) as reactive additives to promote dispersion of the clay platelets. The influence of the clay content o ...

Intercalates and exfoliates formed from layered materials and dendritic polymers are disclosed, together with the uses of these materials, e.g. in producing composite materials. The dispersion of layered materials in a dendritic polymer matrix (hyperbranch ...

The fracture properties and microdeformation behaviour and their correlation with structure in commercial bulk polyolefins are reviewed. Emphasis is on crack-tip deformation mechanisms and on regimes of direct practical interest, namely slow crack growth in polyethylene and high-speed ductile brittle transitions in isotactic polypropylene. Recent fracture studies of reaction-bonded interfaces are also briefly considered, these representing promising model systems for the investigation of the relationship be

The crystallization kinetics of polyamide-12 has been investigated using a combination of differential scanning calorimetry (DSC) and hot-stage optical microscopy. The DSC data for isothermal crystallization were consistent with a simple two-parameter Avrami model for isothermal crystallization and optical measurements of the spherulite growth rates and nucleation density. On the basis of semiempirical expressions for these quantities, it is shown that with small adjustments the model can also account for D

John Christopher Plummer

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Enhanced ductility in high performance polyamides due to strain-induced phase transitions

Structure and deformation mechanisms in UHMWPE-fibres

Fracture mechanisms in polystyrene/laponite nanocomposites prepared by emulsion polymerization

Effect of substrate crystalline morphology on the adhesion of plasma enhanced chemical vapor deposited thin silicon oxide coatings on polyamide

Damping of thermoset and thermoplastic flax fibre composites

Phase separation in epoxy resin-reactive dendritic hyperbranched polymer blends

The morphology of submicronsized core–shell latex particles: An electron microscopy study

Testing of Polymeric Materials

Rheological and physical properties of aliphatic hyperbranched polyesters

Influence of molecular architecture on the isothermal time-dependent response of amorphous shape memory polyurethanes

Essential work of fracture of polypropylene and polypropylene blends over a wide range of test speeds

Thermal and dynamic mechanical properties of blends of bitumen with metallocene catalyzed polyolefins

Morphology of polymer/clay latex particles synthesized by miniemulsion polymerization: Modeling and experimental results

Towards Textile-Based Fiber Reinforced Thermoplastic Nanocomposites: Melt Spun Polypropylene-Montmorillonite Nanocomposite Fibers

Microdeformation in heterogeneous polymers revealed by electron microscopy

Influence of processing routes on morphology and low strain stiffness of polymer/nanofibrillated cellulose composites

Correlating the rheological and mechanical response of polyurethane nanocomposites containing hyperbranched polymers

Composites and methods for their production

Microdeformation and Fracture in Bulk Polyolefins

The crystallization kinetics of polyamide-12