James Adams

Dr James Adams


Lecturer
MA, MSci, PhD, PGCAP
14 BB 03

Academic and research departments

Department of Physics.

Biography

Areas of specialism

Soft Condensed Matter Theory

University roles and responsibilities

  • Departmental duties Level 1 Coordinator 2009-2014
  • Member of the Board of Studies Sub-Committee 2009-2014
  • Member of the Staff Student Liaison Committee 2009-2019
  • Chairman of the Board of Studies Sub-Committee 2014-2019
  • Chairman of the Board of Studies 2014-2019
  • Member of the Quality and Standards Subcommittee 2018-2019

    Research

    Research interests

    Research projects

    Indicators of esteem

    • Visiting Fellow of Isaac Newton Institute for Mathematical Sciences, University of Cambridge, and Fitzwilliam College Cambridge, June 2013.

    Supervision

    Completed postgraduate research projects I have supervised

    Postgraduate research supervision

    My teaching

    Courses I teach on

    Undergraduate

    My publications

    Publications

    Adams JM, Warner M (2006) Spontaneous shears in smectic elastomers,PHYSICAL REVIEW E73(3)ARTN 031706 AMERICAN PHYSICAL SOC
    Adams JM, Mao Y, Vandoolaeghe WL (2007) Stress relaxation in polymer networks: Equilibrium behavior and dynamics,JOURNAL OF CHEMICAL PHYSICS127(11)ARTN 114907 AMER INST PHYSICS
    Clarke SM, Messe L, Adams J, Inaba A, Arnold T, Thomas RK (2003) A quantitative parameter for predicting mixing behaviour in adsorbed layers: the 2D isomorphism coefficient, Chemical Physics Letters3735pp. 480-480 Elsevier
    Stride JA, Adams JM, Johnson MR (2005) Lattice modes of hexamethylbenzene studied by inelastic neutron scattering, Chemical Physics3172pp. 143-143 Elsevier
    Adams JM, Warner M, Stenull O, Lubensky TC (2008) Smectic-A elastomers with weak director anchoring,PHYSICAL REVIEW E78(1)ARTN 011703 AMER PHYSICAL SOC
    Adams JM, Warner M (2009) Mechanical switching of ferroelectric rubber,PHYSICAL REVIEW E79(6)ARTN 061704 AMER PHYSICAL SOC
    Adams JM, Warner M (2005) Elasticity of smectic-A elastomers,PHYSICAL REVIEW E71(2)ARTN 021708 AMERICAN PHYSICAL SOC
    Adams JM, Warner M (2008) Mechanical response of smectic-C elastomers,PHYSICAL REVIEW E77(2)ARTN 021702 AMER PHYSICAL SOC
    Stenull O, Lubensky TC, Adams JM, Warner M (2008) Smectic-$C$ tilt under shear in smectic-$A$ elastomers,PHYS REV E78pp. 021705-021705 APS
    Adams JM, Warner M (2005) Hairpin rubber elasticity, EUROPEAN PHYSICAL JOURNAL E16(1)pp. 97-107 SPRINGER
    Adams JM (2004) On the polarization of chiral main-chain liquid-crystalline elastomers, EUROPEAN PHYSICAL JOURNAL E14(3)pp. 277-285 SPRINGER
    Corbett DR, Adams JM (2013) Tack energy and switchable adhesion of liquid crystal elastomers, Soft Matter91151pp. 1151-1163 The Royal Society of Chemistry
    The mechanical properties of liquid crystal elastomers (LCEs) make them suitable candidates for pressure sensitive adhesives (PSAs). Using the nematic dumbbell constitutive model, and the block model of PSAs, we study their tack energy and the debonding process as could be measured experimentally in the probe-tack test. To investigate their performance as switchable PSAs we compare the tack energy for the director aligned parallel, and perpendicular to the substrate normal, with that for the isotropic state. We find that the tack energy is larger in the parallel alignment than the isotropic case by over a factor of two. The tack energy for the perpendicular alignment can be 50% less than the isotropic case. We propose a mechanism for reversibly switchable adhesion based on the reversibility of the isotropic to nematic transition. Finally we consider the influence of several material parameters that could be used to tune the stress?strain response.
    Adams JM, Warner M (2005) Soft elasticity in smectic elastomers,PHYSICAL REVIEW E72(1)ARTN 011703 AMERICAN PHYSICAL SOC
    Adams JM, Fielding SM, Olmsted PD (2008) The interplay between boundary conditions and flow geometries in shear banding: Hysteresis, band configurations, and surface transitions, JOURNAL OF NON-NEWTONIAN FLUID MECHANICS151(1-3)pp. 101-118 ELSEVIER SCIENCE BV
    Adams JM, Olmsted PD (2009) Adams and olmsted reply:,Physical Review Letters103(21)
    A Reply to the Comment by Shi-Qing Wang. © 2009 The American Physical Society.
    Adams JM, Ivanov AS, Johnson MR, Stride JA (2004) Cracking a chemical conundrum, Physica B: Physics of Condensed Matter3501pp. E351-E351 Elsevier
    Adams J, Conti S, DeSimone A (2007) Soft elasticity and microstructure in smectic-$C$ elastomers,Continuum Mechanics and Thermodynamics186pp. 319-319 Springer Berlin / Heidelberg
    Adams J, Conti S, DeSimone A, Dolzmann G (2008) Relaxation of a transversally isotropic energy and application to smectic A elastomers, Mathematical Models and Methods in Applied Sciences (M3AS)18(1)pp. 1-20
    Adams JM, Fielding SM, Olmsted PD (2011) Transient shear banding in entangled polymers: A study using the Rolie-Poly model,JOURNAL OF RHEOLOGY55(5)pp. 1007-1032 JOURNAL RHEOLOGY AMER INST PHYSICS
    Brown AW, Adams JM (2013) Numerical study of stretched smectic-A elastomer sheets,Physical Review E - Statistical, Nonlinear, and Soft Matter Physics88(1)
    We present a numerical study of stretching monodomain smectic-A elastomer sheets, computed using the finite element method. When stretched parallel to their smectic layer normal the smectic layers are unstable to a transition to a buckled state. We model macroscopic deformations by replacing the microscopic energy with a coarse grained effective free energy that accounts for the fine-scale layer buckling. We augment this model with a term to describe the energy of deforming buckled layers, which is necessary to reproduce the experimentally observed Poisson ratios postbuckling. We examine the spatial distribution of the microstructure phases for various stretching angles relative to the layer normal and for different length-to-width aspect ratios. When stretching parallel to the layer normal the majority of the sample forms a bidirectionally buckled microstructure, except at the clamps where a unidirectionally buckled microstructure is predicted. When stretching at small inclinations to the layer normal the phase of the sample is sensitive to the aspect ratio of the sample, with the bidirectionally buckled phase persistent to large angles only for small aspect ratios. We relate these theoretical results to experiments on smectic-A elastomers. © 2013 American Physical Society.
    Spillmann CM, Konnert JH, Adams JM, Deschamps JR, Naciri J, Ratna BR (2010) Strain analysis of a chiral smectic-A elastomer,PHYSICAL REVIEW E82(3)ARTN 031705 AMER PHYSICAL SOC
    Makepeace David, Locatelli P, Lindsay C, Adams James, Keddie Joseph (2018) Colloidal Polymer Composites: Are Nano-Fillers Always Better for Improving Mechanical Properties?,Journal of Colloid and Interface Science523pp. 45-55 Elsevier
    Hypothesis

    Colloidal polymer composites, in which polymer particles are blended with a filler, are widely used in applications including pharmaceuticals, crop protection, inks, and protective coatings. It is generally found that the presence of hard particulate fillers will increase the elastic modulus of a polymer colloid composite. However, the influence of the size of the filler particle on the large-strain deformation and fracture and on the viscoelastic characteristics, including creep, is not well explored. We hypothesize that the size ratio of the filler to the colloidal polymer will play a critical role in determining the properties of the composite.

    Experiments

    Colloidal composites were prepared by blending soft polymer colloids (as a binder) with calcium carbonate fillers having four different sizes, spanning from 70 nm to 4.5 mm. There is no bonding between the filler and matrix in the composites. The large-strain deformation, linear viscoelasticity, and creep were determined for each filler size for increasing the filler volume fractions (fCC). Weibull statistics were used to analyze the distributions of strains at failure.

    Findings

    We find that the inclusion of nano-fillers leads to brittle fracture at a lower fCC than when mm-size fillers are used. The data interpretation is supported by Weibull analysis. However, for a given fCC, the storage modulus is higher in the rubbery regime, and the creep resistance is higher when nanoparticles are used. Using scanning electron microscopy to support our arguments, we show that the properties of colloidal composites are correlated with their microstructure, which can be altered through control of the filler:polymer particle size ratio. Hard nanoparticles pack efficiently around larger particles to provide reinforcement (manifested as a higher storage modulus and greater creep resistance), but they also introduce weak points that lead to brittleness.

    Adams J, Corbett D (2018) Transient shear banding in the nematic dumbbell model of liquid crystalline polymers,Physical Review E97(5)052601pp. 052601-1 - 052601-15 American Physical Society
    In the shear flow of liquid crystalline polymers (LCPs) the nematic director orientation can align with the flow direction for some materials but continuously tumble in others. The nematic dumbbell (ND) model was originally developed to describe the rheology of flow-aligning semiflexible LCPs, and flow-aligning LCPs are the focus in this paper. In the shear flow of monodomain LCPs, it is usually assumed that the spatial distribution of the velocity is uniform. This is in contrast to polymer solutions, where highly nonuniform spatial velocity profiles have been observed in experiments. We analyze the ND model, with an additional gradient term in the constitutive model, using a linear stability analysis. We investigate the separate cases of constant applied shear stress and constant applied shear rate. We find that the ND model has a transient flow instability to the formation of a spatially inhomogeneous flow velocity for certain starting orientations of the director. We calculate the spatially resolved flow profile in both constant applied stress and constant applied shear rate in start up from rest, using a model with one spatial dimension to illustrate the flow behavior of the fluid. For low shear rates flow reversal can be seen as the director realigns with the flow direction, whereas for high shear rates the director reorientation occurs simultaneously across the gap. Experimentally, this inhomogeneous flow is predicted to be observed in flow reversal experiments in LCPs.
    Richardson Philip, Martín-Fabiani Ignacio, Shaw Patrick, Alsaffar Eman, Velasquez Emilie, Gardner Paul, Shaw Peter, Adams James Michael, Keddie Joseph L. (2019) Competition between Crystallization and Coalescence during the Film Formation of Poly(Chloroprene) Latex and Effects on Mechanical Properties,Industrial & Engineering Chemistry Research58(46)pp. 21031-21043 American Chemical Society
    Poly(chloroprene) is a synthetic crystallizable polymer used in several applications, including rubber gloves. The film formation of poly(chloroprene) latex offers opportunities to define structures at length scales between the molecular and macroscopic, thereby adjusting the elastomer?s mechanical properties. However, the connections between processing and the resultant film properties are not fully understood. Here, we investigate the competition between the coalescence of latex particles to build cohesive strength and their crystallization to raise the elastic modulus. We demonstrate that when coalescence precedes crystallization, the elastomer has greater extensibility and a higher tensile strength compared to when crystallization occurs during coalescence. The mechanical properties of poly(chloroprene) were tuned by blending two colloids with differing gel contents and crystallizabilities. Heating above poly(chloroprene)?s melting temperature allows increased particle interdiffusion and builds cohesion, prior to recrystallization. We provide evidence from in situ wide-angle X-ray scattering for the strain-induced crystallization of as-cast films from particle blends.