Author
Julian F. Johnson
Bio: Julian F. Johnson is an academic researcher from University of Connecticut. The author has contributed to research in topics: Liquid crystal & Gel permeation chromatography. The author has an hindex of 29, co-authored 151 publications receiving 3866 citations.
Papers published on a yearly basis
Papers
More filters
01 Jan 1970
TL;DR: In this paper, the authors present a NMR study of the transition of a mixture of two Isomeric Cyano-Ester homologous series, showing that the phase transition of one of the two isomeric versions of this series is a transition of the other.
Abstract: Some Novel Ferroelectric Smectic Liquid Crystals.- Liquid Crystalline Esters of Phenylhydroquinone and 3-Phenyl 4-Hydroxybenzoic Acid.- The Synthesis and Characterization of Some Perylene and Anthraquinoic Dichroic Dyes for Liquid Crystal Display Applications.- Some New Thermotropic Discogens.- Syntheses and Properties of Liquid Crystalline Heterocycloalkanes.- Characterization of Two Isomeric Cyano-Ester Homologous Series -I.- Effects of Molecular Length on Nematic Mixtures - IV: Structure Effects on Viscosity of Ester Mixtures.- Orientational Disorder in Smectic Liquid Crystals: An Aspect of Structure that has to be Included.- Effect of Molecular Structure of Rigid - Flexible Polyesters on Their Thermotropic Liquid Crystalline Properties.- Relationships Between Molecular Structure and the Incidence of Crystal B and Hexatic B Phases.- Characterization of the Phases of Two Isomeric Cyano-Ester Homologous Series - II.- Unusual Glass Transition of Smectic Liquid Crystal in p-n-Hexyloxybenzylidene-p'-Butylaniline.- Some High Electric Field Effects in Nematic Liquid Crystals.- Application of Generalized Van Der Waals Theory of Homologous Nematogens - Part 1: Trans-4-Ethoxy-4'-N-Alkanoyloxyazobenzenes..- Application of Regular Solution Theory to Discotic Mesophases: Calculation of Phase Diagrams Exhibiting Minima.- Extension of McMillan's Model to Liquid Crystals of Disc-Like Molecules.- Thermotropic Liquid-Crystalline Polymers with Mesogenic Groups and Flexible Spacers in the Main Chain.- Effect of Mesogenic Unit and Spacer Structures on the Thermotropic Properties of Main Chain Liquid Crystal Polyesters.- The Role of Sequence Distribution on Liquid Crystalline Properties of Aromatic Copolyesters.- Diffusion of Rigid Polyamides Through Swollen Gel of Same.- The Molecular Weight Dependence of the Splay and Bend Elastic Constants of a Polymer Liquid Crystal.- DSC, Miscibility and X-ray Studies of the Thermotropic Liquid Crystalline Polyesters with Aromatic Moieties and Flexible Spacers in the Main Chain.- Influence of the Leprosy Drug, Dapsone, on the Phase Transitions of the Lyotropic, Dipalmitoy1 Phosphatidylcholine (DPPC).- Nonaqueous Lyotropic Liquid Crystals of Lecithin and Oligomers of Polyethylene Glycols.- The Diamagnetic Anisotropy of Lyotropic Nematic Mesophases.- Physical Models of Lipid Membranes in Latent Cancer Cells: Ordering Effects of Petroleum Hydrocarbons.- Adiabatic Compression: A New Method to Measure Latent Heats in Phospholipid Bilayers.- Anisotropy of the Electric Conductivity in Amphiphilic Liquid Crystals.- Phase Transition Properties of Bilayers of Mixed Lipids and Their Covalent Analogs.- On The Orientation of Liquid Crystals by Monolayers of Amphiphilic Molecules.- Refractive Index Measurements Using a Double Arm Converging Beam Interferometer.- A Pulsed NMR Study of Transient and Persistent Molecular Order in Nematic Liquid Crystals.- The Effect of Twist on Biaxial Ordering in the Cholesteric Phase.- Deuteron Magnetic Relaxation and Molecular Dynamics in Thermotropic Liquid Crystals.- An Effective Proton Hyperfine Tensor for Di-Tertbutylnitroxide.- Alkyl Chain Flexibility in Liquid Crystals.- Orientational Order in Binary Mixtures of Nematic Liquid Crystals.- The Effect of the Tricritical Region on the Smectic A - Smectic C Transition.- Spatial Correlations in Nematic Liquid Crystals.- Molecular Structure and Ordering in Liquid Crystals.- New Liquid Crystals, Polymeric and Monomeric, Derived From Binaphthyl.- Ioneneomeric Liquid Crystals.- Mesomorphic Properties of an Homologous Series of Alkyl-Terminated Enamine-Ketone Containing Liquid Crystals.- Liquid Crystalline Polymers with Amphiphilic and Non Amphiphilic Side Chains - Effect of the Main Chain on the Phase Behaviour.- The Fluid Mesophases of Polar Rods.- The Nematogeneity of Some Hydrocarbons.- Some Heterocyclic Analogues of Biphenyl Mesogens.- Alignment of Liquid Crystal Molecules on Various Surfaces: Myths, Theories, Facts.- Development of Dual-Frequency Addressable Liquid Crystals.- Dielectric Studies of Monoester and Diester Nematogens.- Intermolecular Guest-Host Interactions and the Optical Order Parameter of Pleochroic Dyes.- Liquid Crystal Alignment on Substrate Surfaces, A Collective Phenomenon.- Alignment of Liquid Crystals in the Vicinity of the SmA-N Transition.- Nematic-Substrate Interaction and the Boundary Layer Phase Transition.- Optical Properties of the Blue Phase of Cholesteric Liquid Crystals.- Lattice Parameters in Blue Phase Mixtures.- Blue Phase Structure Analysis by Optical Bragg Diffractions.- Mesomorphic Polymers as Three Component Systems.- Colloidal Crystals and Glasses.- Self Diffusion Constant and Viscosity of Charged Polystyrene Colloids.- Influence of Molecular Conformation on the Helical Twisting Power of Terpenes in Nematic Liquid Crystals.- Vibrational Spectra of Liquid Crystals XIII: Crystallization Kinetics Study of 4, Octyloxy, 4', Cyano Biphenyl by Rapid Raman Spectroscopy..- Nuclear Spin-Lattice Relaxation Due to Orientational Fluctuation in Smectic Liquid Crystals.- NMR Studies of Molecules Oriented in Mixed Thermotropic Liquid Crystals of Opposite Diamagnetic Anisotropies.- Discotic Mesophase: A Complementary Review.- Identification of the Structure of Mesomorphic Polymers by Means of their Miscibility.- Effect of Molecular Structure on Mesomorphism: Difluorinated Siamese Twin Mesogens.- Anisotropy Induced in a Semi-Flexible Polymer by a Liquid-Crystalline Solvent.- Electrooptical Behaviour of a Novel Strong-Weak Anchored Nematic Layer: First Measurements of MBBA Flexoelectric Coefficient of Splay elz.- On Thermotropic Disc-Like Mesogens.- On The Nature of the Smectic-C Phase.- Contributors.
1,036 citations
TL;DR: A review of the literature published over the last ten years on polymer mechanical properties as a function of molecular weight and molecular weight distribution, Thermal properties, stress-strain properties, impact, fracture, fatigue, creep, stress relaxation and cracking and crazing are examined for a wide variety of homopolymers and a limited number of copolymers.
Abstract: This work reviews the literature published over the last ten years on polymer mechanical properties as a function of molecular weight and molecular weight distribution, Thermal properties, stress-strain properties, impact, fracture, fatigue, creep, stress relaxation and cracking and crazing are examined for a wide variety of homopolymers and a limited number of copolymers. In general, mechanical properties increase as the molecular weight increases. However, above some limiting molecular weight the mechanical property is usually unaffected. Although much work has been done to describe the effects of molecular weight on mechanical properties, little quantitative correlation exists. The available equations to predict such properties as cracking and crazing, Tg, Tm and tensile strength from molecular characteristics are discussed in detail. However, a more quantitative description incorporating a wider range of mechanical properties would be more useful. This would facilitate use of the vast amount of information available and enable it to be applied more readily to new polymer systems.
303 citations
293 citations
01 Jan 1972
TL;DR: The characterization of the complete molecular weight distribution curve by fractionation methods has been difficult to perform for a number of reasons, such as fraction collection and the determination of the various molecular weight averages of polymers is time consuming as discussed by the authors.
Abstract: The molecular weight and molecular weight distribution of a polymer can markedly affect its mechanical properties. While this has been recognized for a long time, quantitative studies have been relatively difficult to perform for a number of reasons. A major problem has been the characterization of the complete molecular weight distribution curve by fractionation methods because fraction collection and the determination of the various molecular weight averages of polymers is time consuming. Additionally, measurement of the number-average molecular weight, [Mbar]n, by classical osmometry procedure is often unreliable.
140 citations
Cited by
More filters
1,429 citations
1,296 citations
TL;DR: In this paper, a new electrooptical effect in twisted nematic liquid crystals is described which allows variation of the rotation of linearly polarized light continuously from 0° to 90°.
Abstract: A new electro‐optical effect in twisted nematic liquid crystals is described which allows variation of the rotation of linearly polarized light continuously from 0° to 90°. It requires lower voltages than other electro‐optic effects.
1,090 citations
01 Jan 1974
1,090 citations
TL;DR: The amount of plastics accumulating in the environment is growing rapidly, yet our understanding of its persistence is very limited as discussed by the authors, and the amount of plastic waste is currently generated at a rate approaching 400 Mt year−1.
Abstract: Plastic waste is currently generated at a rate approaching 400 Mt year–1. The amount of plastics accumulating in the environment is growing rapidly, yet our understanding of its persistence is very...
1,087 citations