Thermo-Mechanical Behavior of Polymer Composites Exposed to Fire

Dissertation submitted to the faculty of the Virginia Polytechnic Institute and State University

pdf format of this dissertation

ABSTRACT
One of the most critical issues for Polymer Matrix Composites (PMCs) in naval applications is the structural performance of composites at high temperature such as that experienced in a fire. A three-dimensional model including the effect of orthotropic viscoelasticity and decomposition is developed to predict the thermo-mechanical behavior and compressive failure of polymer matrix composites (PMCs) subjected to heat and compressive load. An overlaid element technique is proposed for incorporating the model into commercial finite element software ABAQUS. The technique is employed with the user subroutines to provide practicing engineers a convenient tool to perform analysis and design studies on composite materials subjected to combined fire exposure and mechanical loading.
The resulting code is verified and validated by comparing its results with other numerical results and experimentally measured data from the one-sided heating of composites at small (coupon) scale and intermediate scale. The good agreement obtained indicates the capability of the model to predict material behavior for different composite material systems with different fiber stacking sequences, different sample sizes, and different combined thermo-mechanical loadings.
In addition, an experimental technique utilizing Vacuum Assisted Resin Transfer Molding (VARTM) is developed to manufacture PMCs with a hypodermic needle inserted for internal pressure measurement. One-sided heating tests are conducted on the glass/vinyl ester composites to measure the pressure at different locations through thickness during the decomposition process. The model is employed to simulate the heating process and predict the internal pressure due to the matrix decomposition. Both predicted and measured results indicate that the range of the internal pressure peak in the
designed test is around 1.1-1.3 atmosphere pressure. Download pdf formatn and read more

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Flame retardants and heat release: review of data on individual polymers

Article first published online: 11 MAR 2014 in Fire and Materials.

SUMMARY

This work is the second of two parts that considered the following issue: do flame retardants affect heat release of polymers? The reason for investigating the issue is because it is important to assess whether the addition of flame retardants positively decreases fire hazard. This part of the work considered the two following issues. (1) Analysis of the individual polymeric materials that need to be studied. (2) Analysis of the data found on heat release (particularly peak heat release rate), ignitability (if available), and other thermal properties (as available) of polymers in small-scale test data in recent years. The effects are being presented in terms of the percentage of improvement.

The work demonstrated that, almost without exception, when adequately compounded systems were developed, the peak heat release rate of the flame retarded system was lower than that of the non-flame retarded system. The overall conclusion of the two-part study was that flame retardants does indeed improve fire safety (when used appropriately) and that a key reason for the beneficial effect of flame retardants is that they decrease heat release.

A review of fire blocking technologies for soft furnishings

A review by Shonali Nazaré and Rick D Davis

       Download this review,  pdf document, click here

European Commission Decision- Ecolabel for textile products

EU Ecolabels recognise fire safety
Updated “ecological criteria” for the EU Flower Ecolabel for textile products (5thJune 2014) and for bed mattresses (23 June 2014) recognise fire safety and flame retardants as necessary to achieve this. Durabilityof flame retardancy is specified as a criterion for “fitness for use”. Substances subject to certain hazardclassifications are “derogated” (that is, accepted for use) where the product “is required to meet fire protection requirements in ISO, EN, Member State or public sector procurement standards and regulations ”   European Commission Decision: CLICK HERE
Source: pinfa newsletter

Hyperbranched poly(phosphoester)s as flame retardants for technical and high performance polymers

First published online 08 Sep 2014 in Polymer Chemistry.

Abstract:

A structurally novel hyperbranched halogen-free poly(phosphoester) (hbPPE) is proposed as a flame retardant in poly(ester)s and epoxy resins. hb polymeric flame retardants combine several advantages that make them an extraordinary approach for future flame retardants. hbPPE was synthesized by olefin metathesis polymerization according to a straightforward two-step protocol. The impact of hbPPE on pyrolysis, flammability (reaction-to-small-flame), and fire behavior under forced flaming conditions (cone calorimeter) was investigated for a model substance representing poly(ester)s, i.e. ethyl 4-hydroxybenzoate, and an epoxy resin of bisphenol A diglycidyl ether cured with isophorone diamine. The flame retardancy performance and mechanisms are discussed and compared to a commercial bispenhol A bis(diphenyl phosphate) (BDP). Both hbPPE and BDP combined gas-phase and condensed-phase activity; hbPPE is the more efficient flame retardant, and is proposed to be efficient in a greater variety of polymeric matrices. The hydrolysis of hbPPE is suggested to produce phosphorous acids, which, when available at the right temperatures, enhance the charring of the polymer in the condensed phase. The better fire protection behavior of the hbPPE is due not only to its higher phosphorus content, but also to the higher efficiency of the phosphorus it contains.

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