Stimulating changes in the elastic modulus of polymer materials by molecular photochromism

RSC Advances ◽  
2014 ◽  
Vol 4 (108) ◽  
pp. 62920-62925 ◽  
Author(s):  
Yuhuan Jin ◽  
Daniel Harrington ◽  
Aaron A. Rachford ◽  
Jeffrey J. Rack
Keyword(s):  
Elastic Modulus ◽  
Amorphous Polymer ◽  
Polymer Materials

Photonastic effects are observed in an amorphous polymer via irradiation of a pendant photoreversible photochrome.

scholarly journals Reflectance According to Cell Size, Foaming Ratio and Refractive Index of Microcellular Foamed Amorphous Polymer

2019 ◽  
Vol 20 (23) ◽  
pp. 6068 ◽  
Author(s):  
Sung Woon Cha ◽  
Soo-hyun Cho ◽  
Joo Seong Sohn ◽  
Youngjae Ryu ◽  
Jeonghun Ahn
Keyword(s):  
Refractive Index ◽  
Cell Size ◽  
Amorphous Polymer ◽  
High Specific Surface Area ◽  
Polymer Materials ◽  
Light Passing ◽  
Foaming Process ◽  
Microcellular Foaming ◽  
Cell Structures ◽  
A Cell

Microcellular foamed plastic has a cell size of approximately 0.1 to 10 microns inside a foamed polymer and a cell density in the range of 109 to 1015 cells/cm3. Typically, the formation of numerous uniform cells inside a polymer can be effectively used for various purposes, such as lightweight materials, insulation and sound absorbing materials. However, it has recently been reported that these dense cell structures, which are induced through microcellular foaming, can affect the light passing through the medium, which affects the haze and permeability and causes the diffused reflection of light to achieve high diffuse reflectivity. In this study, the effects of cell size, foaming ratio and refractive index on the optical performance were investigated by applying the microcellular foaming process to three types of amorphous polymer materials. Thus, this study experimentally confirmed that the advantages of porous materials can be implemented as optical properties by providing a high specific surface area as a small and uniform cell formed by inducing a high foaming ratio through a microcellular foaming process.

Mechanical characterization of rigid π-conjugated polymer on a nanometer scale through nanoindentation

e-Polymers ◽  
2012 ◽  
Vol 12 (1) ◽  
Author(s):  
Bo Liang ◽  
Zhen-lin Zhang ◽  
Lai-Lei Wu ◽  
Li-cheng Zhao ◽  
Shuai Zhang ◽  
...  
Keyword(s):  
Elastic Modulus ◽  
Conjugated Polymer ◽  
Loading Rate ◽  
Mechanical Performance ◽  
Experimental Parameter ◽  
Effective Elastic Modulus ◽  
Polymer Materials ◽  
Experimental Result ◽  
Important Significance

AbstractThe evaluating mechanical performance of Π-conjugated Polymer films has important significance for application in the micro electronic devices. In this work, authors studied micro mechanical performance of Π-conjugated polymer, poly[2-methoxy-5-(2’-ethyl hexyloxy)-phenylene vinylene] used nanoindentation technique at room temperature and discussed effect of experimental parameter on the effective elastic modulus and hardness of MEH-PPV film. The experimental result indicates the estimating effective elastic modulus and hardness using O & P formula are correlative with load, holding time, and loading rate. Detail analysis in combination with related literature indicated the effective elastic modulus and hardness of MEH-PPV film are approximately 6.79±0.12GP, 0.37±0.16 GP, respectively. Furthermore, increasing the loading rate could decrease the effective elastic modulus and hardness, which was opposite comparing with typical polymer materials (poly (methyl methacrylate) (PMMA) etc ).

Mapping of Nanoscale Mechanical Properties of Polymers in Quasi-static and Oscillatory Atomic Force Microscopy Modes

MRS Advances ◽  
2016 ◽  
Vol 1 (40) ◽  
pp. 2763-2768 ◽  
Author(s):  
Sergei Magonov ◽  
Marko Surtchev ◽  
John Alexander ◽  
Ivan Malovichko ◽  
Sergey Belikov
Keyword(s):  
Mechanical Properties ◽  
Atomic Force Microscopy ◽  
Elastic Modulus ◽  
Polymer Materials ◽  
Work Of Adhesion ◽  
Force Microscopy ◽  
Atomic Force ◽  
Time Dependencies ◽  
Force Curves ◽  
20 Nm

ABSTRACTRecent advances in studies of local mechanical properties of polymers with different atomic force microscopy techniques (contact, Hybrid and amplitude modulation modes) are described in interplay between experiment and theory. Analysis of force curves and time dependencies of probe response to sample compliance, which were recorded on a number of polymer materials at various temperatures, leads to quantitative mapping of specific mechanical properties (elastic modulus, work of adhesion, etc). High spatial resolution of elastic modulus mapping (10-20 nm) is illustrated in measurements of lamellar structures of several polymers. Challenges of examination of viscoelastic properties are pointed out and a possible solution is presented.

Nanoscale Dynamic Viscoelastic Measurements at Elevated Temperature

2012 ◽  
Vol 1424 ◽  
Author(s):  
Jiping Ye ◽  
Satoshi Shimizu
Keyword(s):  
Surface Layer ◽  
Elastic Modulus ◽  
Elevated Temperatures ◽  
Thermal Protection ◽  
Measurement Data ◽  
Fused Silica ◽  
Polymer Materials ◽  
Small Scale ◽  
Nanoindentation Measurement ◽  
Significant Difference

ABSTRACTA nanoscale dynamic mechanical analysis (nano-DMA) measurement method has been successfully developed for use in evaluating nanoscale dynamic viscoelastic properties in small-scale polymer materials over a range of non-ambient temperatures from -120 oC to 500 oC. Measurements have been obtained with a nanoindentation measurement system, in which two key techniques are applied. One is a thermal protection system for control and prevention of thermal drift and noise. The other is an environmental control system for preventing corrosion at high temperatures and dew condensation at low temperatures. Measurement reliability was examined by using a combination of a thermal-mechanically stable fused silica and a homogeneous sample of isotropic polyethylene terephthalate (PET). Constant hardness and modulus values of the fused silica from -120 oC to 500 oC indicated that the measurements were not affected by thermal load drift and noise even at elevated temperatures. The PET sample exhibited no significant difference in temperature dispersions of storage elastic modulus, loss elastic modulus and loss tangent between the nanoindentation measurement data and bulk data measured with a conventional DMA method. A practical application involving surface-deteriorated polyethylene (PE) tubes was used to demonstrate the validity and usefulness of this nano-DMA method. Infrared spectroscopic imaging revealed that the surface layer of the PE tubes was oxidized to form a carbonylated (O=C<) layer. The storage elastic modulus and glass-transition temperature of the surface layer were much higher than the corresponding values of the interior. These data indicate a plausible reason for why the PE tube surface deteriorates to form brittle cracks.

scholarly journals DYNAMIC THREE-POINTS-BENDING TEST MODE OF TWO AMORPHOUS POLYMER MATERIALS (PMMA, PC) FOR THEIR VISCOELASTIC AND MECHANICAL CHARACTERIZATION

2021 ◽  
Vol 9 (08) ◽  
pp. 448-453
Author(s):  
Ayarema Afio ◽  
◽  
Komlan Lolo ◽  
Kodjo Attipou ◽  
Komla Assogba Kassegne ◽  
...  
Keyword(s):  
Industrial Development ◽  
Mechanical Characterization ◽  
Amorphous Polymer ◽  
Amorphous Polymers ◽  
Polymer Materials ◽  
Bending Test ◽  
Embedded Test ◽  
Practical Applications ◽  
Viscoelastic Characteristics

This paper presents an approach to classifying amorphous polymer materials. Temperature is This classification involves the determination of mechanical and viscoelastic characteristics considered a descriptive variable to clarify the specific field of practical applications of amorphous polymers. according to the reference temperature characterizing the behaviour of polymer materials. The mechanical and viscoelastic characteristics of amorphous polymers such as methyl poly-methacrylate (PMMA), polycarbonate (PC) and imide poly ether (PEI) are determined through the three-point dynamically embedded test carried out in an adiabatic close enclosure. The complex dissipative or conservative modules according to the temperature are represented. The results obtained show that the fluidity index of these materials is linked to their viscosity, which is a determining property which is decisive for the choice of the technique of the application of the material. Our method of measuring properties is therefore, in principle, comparable to the techniques used in industrial development.

Solid wood joints by in situ welding of structural wood constituents

Holzforschung ◽  
2004 ◽  
Vol 58 (1) ◽  
pp. 45-52 ◽  
Author(s):  
B. Gfeller ◽  
A. Pizzi ◽  
M. Zanetti ◽  
M. Properzi ◽  
F. Pichelin ◽  
...  
Keyword(s):  
Amorphous Polymer ◽  
Solid Wood ◽  
Polymer Materials ◽  
Cross Linking ◽  
Structural Application ◽  
Wood Fibres ◽  
Entanglement Network ◽  
Melted Material ◽  
C Nmr

Abstract Mechanically-induced wood flow welding, without any adhesive, is here shown to rapidly yield wood joints satisfying the relevant requirements for structural application. The mechanism of mechanically-induced vibrational wood flow welding is shown to be due mostly to the melting and flowing of the amorphous polymer materials interconnecting wood cells, mainly lignin, but also some hemicelluloses. This causes the partial detachment of long wood cells and wood fibres and the formation of an entanglement network in a matrix of melted material which then solidifies. Thus, it forms a wood cell/fibre entanglement network composite having a molten lignin polymer matrix. During the welding period, some of the detached wood fibres no longer held by the interconnecting material are pushed out of the joint as excess fibre. Cross-linking chemical reactions of lignin and of carbohydrate-derived furfural also occur. Their presence has been identified by CP-MAS 13C NMR. These reactions are, however, relatively minor contributors during the very short welding period. Their contribution increases after welding has finished, explaining why relatively longer holding times under pressure after the end of welding contribute strongly to obtaining a good bond.

Synthesis of Ceramics/Polymer Nanocomposites Protonic Conducting Membrane

1998 ◽  
Vol 548 ◽  
Author(s):  
I. Honma ◽  
S. Hirakawa ◽  
J.M. Bae
Keyword(s):  
High Temperature ◽  
Polymer Nanocomposites ◽  
High Temperatures ◽  
Chemical Sensors ◽  
Amorphous Polymer ◽  
Sol Gel ◽  
Hybrid Membrane ◽  
Polymer Materials ◽  
Polyethylene Oxides ◽  
Electrochemical Devices

ABSTRACTHigh temperature protonic conducting polymer membrane provides new technological applications in the electrochemical devices including electrochromic displays, chemical sensors, fuel cells and others. Organic/inorganiaianocomposites membrane consists of SiO2/PEO (Polyethylene Oxides) hybrid are remarkable family of isotropic, amorphous polymer materials, which has been synthesized through sol-gel processes. The hybrid membrane doped with acidic surfactant molecules shows good protonic conductivities at high temperatures above 100C. The membrane was found to be thermally stable at high temperatures because of the inorganic SiO2 framework in the composites matrix.

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