Fluid and Matrix Components of Polyurethane Foam Behavior Under Cyclic Compression

1996 ◽  
Vol 118 (1) ◽  
pp. 58-62 ◽  
Author(s):  
Jackie D. Rehkopf ◽  
Greg M. McNeice ◽  
G. Wayne Brodland
Keyword(s):  
Polyurethane Foam ◽  
Fluid Phase ◽  
Strain Rates ◽  
Rigid Polyurethane Foam ◽  
Matrix Component ◽  
Fluid Component ◽  
Cyclic Compression ◽  
Nominal Strain ◽  
The Matrix ◽  
Matrix Components

Semi-rigid polyurethane foam specimens were compressed to 25, 50, or 75 percent strain at nominal strain rates of 0.14/s, 1.4/s or 14/s for up to 100 cycles. The loads carried by the fluid and matrix phases of the foam were determined over these deformation histories using an experimental method recently developed by the authors. The fluid phase contributed significantly to the first-cycle stress of specimens compressed to 50 or 75 percent strain. During subsequent cycles, the fluid component decreased more quickly than the matrix component and became negligible by 100 cycles.

scholarly journals Enhanced Fire Safety of Rigid Polyurethane Foam via Synergistic Effect of Phosphorus/Nitrogen Compounds and Expandable Graphite

Molecules ◽  
2020 ◽  
Vol 25 (20) ◽  
pp. 4741
Author(s):  
Chuan Liu ◽  
Ping Zhang ◽  
Yongqian Shi ◽  
Xiaohui Rao ◽  
Suncheng Cai ◽  
...  
Keyword(s):  
Synergistic Effect ◽  
Polyurethane Foam ◽  
Fire Safety ◽  
Fire Hazard ◽  
Expandable Graphite ◽  
Nitrogen Compounds ◽  
Rigid Polyurethane Foam ◽  
Gaseous Products ◽  
The Matrix ◽  
Physical Barriers

In order to explore highly efficient flame-retardant rigid polyurethane foam (RPUF), phosphorus/nitrogen compounds and expandable graphite (EG) were successfully incorporated into RPUF by a free one-spot method. The combustion results showed that the fire safety of the RPUF samples was remarkably improved by the addition of phosphoric/nitrogen compounds and EG. With the incorporation of 22.4 wt.% phosphorus/nitrogen compounds and 3.2 wt.% EG, the RPUF composites achieved UL-94 V-0 rating. Besides, the total heat release and total smoke release of RPUF composites were reduced by 29.6% and 32.4% respectively, compared to those of the pure RPUF sample. PO• and PO2• together with nonflammable gaseous products were evolved from phosphoric/nitrogen compounds in the gas phase, which quenched the flammable free radicals in the matrix and diluted the concentration of combustible gaseous products generated from PRUF during combustion. The compact char residues which acted as excellent physical barriers were formed by catalysis of EG and phosphoric/nitrogen compounds in the condense phase. The fire hazard of RPUF was significantly reduced by the synergistic effect of phosphorus-nitrogen compounds and EG. This work provides a promising strategy to enhance the fire safety of RPUF.

Effects of Different Graphite Particle Sizes on the Properties of Rigid Polyurethane Foam

2012 ◽  
Vol 538-541 ◽  
pp. 2425-2428
Author(s):  
Li Guang Xiao ◽  
Guan Jie Li ◽  
Cun You Yan
Keyword(s):  
Thermal Conductivity ◽  
Tensile Properties ◽  
Polyurethane Foam ◽  
Graphite Particle ◽  
Particle Sizes ◽  
Rigid Polyurethane Foam ◽  
Graphite Content ◽  
The Matrix ◽  
Stability Enhancement ◽  
Better Than

By Using Two Different Kinds of the Graphite Particles 80 Mesh and 325 Mesh on the Whole Water-blown Rigid Polyurethane Foam, its Properties Will Be Modified and Improved. the Result Shows that both of them Can Improve the Compressive Strength of Matrix when the Graphite Content Is Low. the 80 Mesh Graphite Destroys the Pore Structure of the Matrix, Resulting in the Increase of the Thermal Conductivity. in Addition, the Tensile Properties Are Reduced. in Contrast, the 325 Mesh Graphite Reduces the Thermal Conductivity of the Matrix, and the Tensile Properties Get Improved. Meanwhile, the Thermal Stability Enhancement of 325 Mesh Graphite Is Better than 80 Mesh Graphite.

Polyimide/Polyimide Molecular Composite Films: Difference between Reactive Oligoimide and Reactive Polyimide as the Matrix Component

1998 ◽  
Vol 10 (1) ◽  
pp. 111-120 ◽  
Author(s):  
Tsutomu Takeichi ◽  
Kohji Nakajima ◽  
Min Zuo ◽  
Rikio Yokota
Keyword(s):  
Composite Films ◽  
Tensile Modulus ◽  
High Glass Transition Temperature ◽  
Matrix Component ◽  
Thermal Imidization ◽  
The Matrix ◽  
Matrix Components ◽  
Biphenyltetracarboxylic Dianhydride ◽  
Internal Acetylene ◽  
Very High

Polyimide/polyimide molecular composite (MC) films were prepared by blending precursor solutions of a rigid polyimide and a reactive oligoimide or a reactive polyimide that contains acetylene units in the backbone in a 7:3 ratio, followed by casting, drying and thermal imidization at 300 °C. 3, 3′, 4, 4′-Biphenyltetracarboxylic dianhydride (BPDA), pyromellitic dianhydride (PMDA), p-phenylenediamine (PDA), oxydianiline (ODA) and 3, 3′-diaminodiphenylacetylene ( m-intA) were used as acid dianhydride and diamine monomers for the preparation of polyimide. The rigid components were prepared from PMDA or BPDA and PDA. The matrix components were prepared from PMDA or BPDA and ODA or m-intA. The polyimide/polyimide MCs have exotherm on DSC due to the reaction of internal acetylene units, which indicates that the MC films are laminate processable. Tensile measurements revealed that the tensile modulus of the MCs utilizing reactive oligoimides is 20–30% higher than that of the MCs utilizing reactive polyimides. Viscoelastic analyses of the MC films showed that the crosslinking of the acetylene units gave polyimides that have a very high glass transition temperature.

Experimental study of horizontal flame spread over rigid polyurethane foam on a plateau: effects of sample width and ambient pressure

2014 ◽  
Vol 39 (2) ◽  
pp. 127-138 ◽  
Author(s):  
Y. Zhou ◽  
H. H. Xiao ◽  
J. H. Sun ◽  
X. N. Zhang ◽  
W. G. Yan ◽  
...  
Keyword(s):  
Experimental Study ◽  
Polyurethane Foam ◽  
Flame Spread ◽  
Ambient Pressure ◽  
Rigid Polyurethane Foam ◽  
Sample Width

scholarly journals Hot Deformation Behavior of a Ni-Based Superalloy with Suppressed Precipitation

Metals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 605
Author(s):  
Franco Lizzi ◽  
Kashyap Pradeep ◽  
Aleksandar Stanojevic ◽  
Silvana Sommadossi ◽  
Maria Cecilia Poletti
Keyword(s):  
Dynamic Recrystallization ◽  
Strain Rate ◽  
Hot Deformation ◽  
Strain Rates ◽  
Compression Tests ◽  
Deformation Bands ◽  
Stress Softening ◽  
Relative Stress ◽  
The Matrix ◽  
Thermomechanical Processes

Inconel®718 is a well-known nickel-based super-alloy used for high-temperature applications after thermomechanical processes followed by heat treatments. This work describes the evolution of the microstructure and the stresses during hot deformation of a prototype alloy named IN718WP produced by powder metallurgy with similar chemical composition to the matrix of Inconel®718. Compression tests were performed by the thermomechanical simulator Gleeble®3800 in a temperature range from 900 to 1025 °C, and strain rates scaled from 0.001 to 10 s−1. Flow curves of IN718WP showed similar features to those of Inconel®718. The relative stress softening of the IN718WP was comparable to standard alloy Inconel®718 for the highest strain rates. Large stress softening at low strain rates may be related to two phenomena: the fast recrystallization rate, and the coarsening of micropores driven by diffusion. Dynamic recrystallization grade and grain size were quantified using metallography. The recrystallization grade increased as the strain rate decreased, although showed less dependency on the temperature. Dynamic recrystallization occurred after the formation of deformation bands at strain rates above 0.1 s−1 and after the formation of subgrains when deforming at low strain rates. Recrystallized grains had a large number of sigma 3 boundaries, and their percentage increased with strain rate and temperature. The calculated apparent activation energy and strain rate exponent value were similar to those found for Inconel®718 when deforming above the solvus temperature.

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