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.

My teaching

Courses I teach on

Supervision

Completed postgraduate research projects I have supervised

Postgraduate research supervision

My publications

Publications

Adams JM, Warner M (2006) Spontaneous shears in smectic elastomers, PHYSICAL REVIEW E 73 (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 PHYSICS 127 (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 Letters 373 5 pp. 480-480 Elsevier
Stride JA, Adams JM, Johnson MR (2005) Lattice modes of hexamethylbenzene studied by inelastic neutron scattering, Chemical Physics 317 2 pp. 143-143 Elsevier
Adams JM, Warner M, Stenull O, Lubensky TC (2008) Smectic-A elastomers with weak director anchoring, PHYSICAL REVIEW E 78 (1) ARTN 011703 AMER PHYSICAL SOC
Adams JM, Warner M (2009) Mechanical switching of ferroelectric rubber, PHYSICAL REVIEW E 79 (6) ARTN 061704 AMER PHYSICAL SOC
Adams JM, Warner M (2005) Elasticity of smectic-A elastomers, PHYSICAL REVIEW E 71 (2) ARTN 021708 AMERICAN PHYSICAL SOC
Adams JM, Warner M (2008) Mechanical response of smectic-C elastomers, PHYSICAL REVIEW E 77 (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 E 78 pp. 021705-021705 APS
Adams JM, Warner M (2005) Hairpin rubber elasticity, EUROPEAN PHYSICAL JOURNAL E 16 (1) pp. 97-107 SPRINGER
Adams JM (2004) On the polarization of chiral main-chain liquid-crystalline elastomers, EUROPEAN PHYSICAL JOURNAL E 14 (3) pp. 277-285 SPRINGER
Corbett DR, Adams JM (2013) Tack energy and switchable adhesion of liquid crystal elastomers, Soft Matter 9 1151 pp. 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 E 72 (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 MECHANICS 151 (1-3) pp. 101-118 ELSEVIER SCIENCE BV
Adams JM, Olmsted PD (2009) Adams and olmsted reply:, Physical Review Letters 103 (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 Matter 350 1 pp. E351-E351 Elsevier
Adams J, Conti S, DeSimone A (2007) Soft elasticity and microstructure in smectic-$C$ elastomers, Continuum Mechanics and Thermodynamics 18 6 pp. 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 RHEOLOGY 55 (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 Physics 88 (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 E 82 (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 Science 523 pp. 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 E 97 (5) 052601 pp. 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.