Barrier Fabric Research Articles

Moisture barrier layer with supplemental chemical and biological protective functionality for firefighting clothing applications

One of the primary constituent layers of fire protective clothing is a flame-retardant, waterproof and breathable moisture barrier, which permits the outward transfer of perspiration from the firefighter’s body, while barring the inward entry of water. The introduction of a chemical and biological resistant functionality can greatly enhance the overall applicability of fire protective clothing. In the present work, a chemical & biological resistant waterproof breathable flame retardant moisture barrier fabric was prepared by laminating a biaxially stretched microporous expanded polytetraflouroethylene (ePTFE) membrane with Activated Carbon Fabric using a hot melt reactive breathable polyurethane adhesive. The developed laminate was found to exhibit an excellent balance of waterproofness (23 kPa) and breathability, which was quantified in terms of water vapour transmission rate (WVTR) and water vapour resistance (Ret). High values of WVTR, 1.1025 × 104 ± 9.8×101 g/m2/day complimented with exceptionally low values of Ret, 2.9 m2Pa/W are indicative of its high degree of breathability. Vertical flammability tests clearly revealed the exceptional flame resistance offered by the laminate, where after-flame, after-glow or melt-dripping was not observed and the char length was ∼4.2 cm. Further, the laminate exhibited requisite degree of protection against biological and chemical warfare (CW) agent with no breakthrough of the CW agent being perceived within the time frame of 24 h. The excellent combination of flame retardancy, breathability, waterproofness, chemical and biological protection, bestows the laminate excellent potential for usage as moisture barrier in fire protective clothing applications.

Assessing fire-blocking effectiveness of barrier fabrics in the cone calorimeter

Cone calorimetry experiments of on flexible polyurethane foam and flexible polyurethane foam covered with a variety of fire-blocking barrier fabrics were used to characterize and rank the effectiveness of barrier fabrics with the ultimate goal being an ability to predict the effectiveness of barrier fabrics for reducing the flammability of residential upholstered furniture. The primary measure used to characterize the burning behavior was heat release rate. The effect of the underlying sample substrate was shown to have a large effect on the burning behavior of flexible polyurethane foam samples, and a thermally insulating substrate was used during composite experiments. At times, rapid heat release rate fluctuations were observed, and in such cases approximate corrections were applied to correct for finite cone calorimeter time response. Measurements using thermocouples placed within the flexible polyurethane foam provided insights on flexible polyurethane foam pyrolysis behavior, the collapse rate of flexible polyurethane foam, and the thermal protective properties of barrier materials. Heat release rate temporal profiles for flexible polyurethane foam showed two distinct burning stages with peak values which have been attributed to sequential burning of species (primarily) derived from the diamine ( PHRR1) and polyol components ( PHRR2) used to manufacture the flexible polyurethane foam. When a barrier fabric was added, many of the composites displayed a three-stage burning behavior which was attributed to an initial short, intense burning (termed flash burning) stage associated with the barrier fabric covering followed by the two flexible polyurethane foam stages. Seven out of 16 flexible polyurethane foam/barrier fabric composites exhibited flame extinction prior to fuel burn out. Five out of the seven composites reignited when the spark ignition source was reapplied. Reignition allowed barrier fabric effectiveness to be assessed even for cases with flame extinction. Barrier fabric performance was shown to be consistent with four properties that were previously identified as important barrier fabric properties: barrier fabric flammability, gas permeability, thermal protection, and physical integrity. In addition, the current experiments indicate the presence and effectiveness of gas-phase active flame retardants in the barrier fabric can also play an important role. A limited number of tests were conducted to de-couple the effects of flame-retardant chemicals and physical effects of barrier fabrics on flexible polyurethane foam burning behavior. These tests showed that while flame-retardant chemicals can be effective in quenching and extinguishing the flames, the presence of effective barrier fabric shells is also very important in lowering the heat release rate of burning flexible polyurethane foam. In general, the presence of a barrier fabric was shown to reduce the heat release rate peak values during both flexible polyurethane foam burning stages. The magnitude of the peak associated with second-stage flexible polyurethane foam burning was deemed the most appropriate for characterizing the thermal protection provided by a barrier fabric. Since the times for PHRR2also varied between composites, a measurement referred to as the peak fire growth rate (PFIGRA) parameter was calculated by dividing the heat release rate by time since time to ignition and PFIGRA2was also considered for characterizing the barrier fabrics. Three possible classification schemes, each consisting of three classes, were introduced based on composite flame extinction and reignition behavior, PHRR2values, and PFIGRA2values. Each scheme provided differentiation between barrier fabric effectiveness. While the schemes were able to assess whether the barrier fabrics were particularly effective or ineffective, there were variations among classes of barrier fabrics having intermediate levels of effectiveness. Further work will be required to assess which, if any, of the classification schemes are most appropriate for predicting barrier fabric performance in residential upholstered furniture.

Analysis and prediction of air permeability of woven barrier fabrics with respect to material, fabric construction and process parameters

Air permeability is one of the important properties of conventional as well as technical fabrics such as protective garments, filters, and fabrics for airbags and parachutes. In case of surgical textiles, air permeability is an effective measure of thermo-physiological comfort. This study is aimed to analyze PES barrier fabrics and to develop correlation between permeability and influential material, construction and process parameters. Not only the individual effects of yarn, fabric and loom parameters but also the underlying complex interactions between fewer or several of these influencing factors exert significant influence on fabric porosity and permeability. Artificial neural network (ANN) is the suitable tool to map such complex input-output relationships, since a direct analytical solution is not possible. Feedforward neural network models were trained with combination of Levenberg-Marquardt algorithm and Bayesian regularization support incorporated in backpropagation. Based on the number of input variables, three ANN models were optimized. It was observed that the model which was trained with all selected inputs delivered promising results on test data, i.e., R2=0.985 and mean absolute error of 1.8%. To eliminate any doubt of overfitting, 10 % cross-validation was also performed for selected final model. Furthermore, to investigate the relative importance of input variables in the optimized ANN model, the rank analysis was also carried out. Research outcomes reveal that ANN can be used to tailor barrier fabric permeability depending on the requirements quickly without trials and error by adjusting loom, fabric and yarn parameters.

Factors for Consideration in an Open-Flame Test for Assessing Fire Blocking Performance of Barrier Fabrics.

The main objective of the work reported here is to assess factors that could affect the outcome of a proposed open flame test for barrier fabrics (BF-open flame test). The BF-open flame test characterizes barrier effectiveness by monitoring the ignition of a flexible polyurethane foam (FPUF) layer placed in contact with the upper side of the barrier fabric, exposed to a burner flame from below. Particular attention is given to the factors that influence the ignitibility of the FPUF, including thermal resistance, permeability, and structural integrity of the barrier fabrics (BFs). A number of barrier fabrics, displaying a wide range of the properties, are tested with the BF-open flame test. Visual observations of the FPUF burning behavior and BF char patterns, in addition to heat flux measurements on the unexposed side of the barrier fabrics, are used to assess the protective performance of the BF specimen under the open flame test conditions. The temperature and heat transfer measurements on the unexposed side of the BF and subsequent ranking of BFs for their thermal protective performance suggest that the BF-open flame test does not differentiate barrier fabrics based on their heat transfer properties. A similar conclusion is reached with regard to BF permeability characterized at room temperature. However, the outcome of this BF-open flame test is found to be heavily influenced by the structural integrity of thermally degraded BF. The BF-open flame test, in its current form, only ignited FPUF when structural failure of the barrier was observed.

Evaluating smoldering behavior of fire-blocking barrier fabrics

This study reports on the smoldering propensity of commercially available barrier fabrics in a small-scale mock-up configuration. Most barrier fabrics are smolder resistant when tested alone over a standard flexible polyurethane foam. However, when covered with a smolder-prone cover fabric, most barrier fabrics failed the smoldering ignition test described in the Consumer Product Safety Commission’s proposed standard 16 CFR Part 1634. The results of this study suggest that the smolder-prone cover fabrics, when placed on top of a number of barrier fabrics, are capable of releasing sufficient heat to initiate the char oxidation smoldering process of some of the barrier fabrics and subsequently transmit the heat to the underlying flexible polyurethane foam. A smoldering index for barrier fabrics was derived from the measured char volume fraction of the flexible polyurethane foam by varying the barrier fabric component in the flexible polyurethane foam/barrier fabric/cover fabric mock-up systems, while holding the other two components constant. The smoldering index for self-extinguishing barrier fabrics was 0. Barrier fabrics with smoldering index of 1 or more resulted in sustained smoldering in the flexible polyurethane foam. The smoldering propensity of barrier fabrics and the amount of heat transmitted to the flexible polyurethane foam varied depending on the barrier fabric structure, fiber content, air permeability, and bulk density. Flame-retardant treatments and use of char-forming fibers showed a greater tendency for barrier fabric smolder in the presence of the smolder-prone cover fabric. Barrier fabrics with char-forming fiber blends had greater smoldering propensity as compared to barrier fabrics with low charring fiber blends. The lower the smoldering propensity of the barrier fabric, the less likely was the development of sustained smoldering in the flexible polyurethane foam.

Propagation protocol for early blue violet (Viola adunca Sm. [Violaceae

Early blue violet (<i>Viola adunca</i> Sm. [Violaceae]) is the key larval host plant of threatened fritillary butterflies found along the western coast of North America. This small-statured species has not been readily available in restoration seed mixes because of the time and cost investments required for collecting seeds and the irregular flower and fruit development that occurs over the course of the growing season. We have developed an efficient method for seed production that facilitates the recovery of the butterfly taxa, and it supplies seeds for grassland restoration projects. Using greenhouse produced seedling plugs and weed barrier fabric in seed production fields allows for the increase and ease of seed collection during multiple years of seed production.

Flame-retardant cotton barrier nonwovens for mattresses

According to regulation CPSC 16 CFR 1633, every new residential mattress sold in the United States since July 2007 must resist ignition by open flame. An environmentally benign “green,” inexpensive way to meet this regulation is to use a low-cost flame-retardant barrier fabric. In this study, a nonwoven fabric of grey unbleached cotton was treated with a low-cost phosphate-based formulation. The energy-dispersive X-ray microanalysis showed uniform nitrogen and phosphorus distribution. With 17% add-on, the flame-retardant unbleached cotton barrier showed a limiting oxygen index of 33% oxygen and 83 mm of char length with no after-flame and no afterglow in the vertical flame test. Under air and nitrogen at 500°C, 24% and 35% char remained after thermogravimetric analyses, respectively. This flame resistance is comparable to that of current commercial barrier fabrics made from bleached cotton and Flovan cyanoguanidine or from T-bond grey cotton fiber highlofts (Jones Fiber). Mattresses constructed with a flame-retardant cotton nonwoven barrier fabric are predicted to meet the requirements of 16CFR1633. As a follow-up to this study, a full-scale mattress burn test is recommended.

A review of fire blocking technologies for soft furnishings

AbstractFire barrier fabrics are expected to play an increasingly important role in complying with existing and proposed soft furnishing flammability regulations in the US. The number of commercial fire blocking technologies is large in order to accommodate the vast requirements of the consumers, manufacturers, and regulatory agencies. Generally, highloft, nonwoven fiber battings are used in residential mattress applications, whereas coated or laminated textiles are more common in institutional and upholstered furnishing applications. Successfully achieving the desired level of fire protection requires appropriate matching of the barrier fabric to the desired characteristics of the soft furnishing. Barrier material selection for soft furnishings is generally a process of trial and error due to significant measurement science gaps.In 2009, the National Institute of Science and Technology and American Fiber Manufacturers Association held a workshop on fire blocking barrier fabrics for soft furnishings to discuss the past, present, and future state of the barrier materials in the US. This manuscript is based on knowledge obtained from the workshop and the subsequent knowledge gathered from literature and stakeholders. Several fire blocking technologies have been explored to reduce the flammability of soft furnishings by preventing or delaying direct flame impingement and heat transfer from the flames or molten polymer to the core components. While previous studies reported on use of fire barriers to comply with full-scale testing of soft furnishing items, they failed to report on assessment of barrier materials as isolated components. In addition to a few examples that demonstrate the complexity that makes a priori selection of fire barrier materials difficult, various fire blocking technologies are discussed in this report with respect to material type, fiber content, and fire blocking mechanisms. Potential test methods for characterizing barrier performance are reviewed. Future trends in fire blocking materials are also briefly described.

Barriers Prevent Emergence of Yellow Nutsedge (Cyperus esculentus) in Annual Plasticulture Strawberry (Fragaria × ananassa)

Yellow nutsedge is a problematic weed in plasticulture strawberry because herbicides and fumigants currently used in California provide little to no control and because nutsedge shoots easily penetrate standard low-density polyethylene (LDPE) mulch to rapidly establish and compete with the crop. Field studies were conducted at two California locations near Oxnard and Camarillo from 2007 to 2009 to evaluate yellow nutsedge control with physical barriers. Nutsedge germinated in both autumn and spring through LDPE mulch alone, but paper placed between two layers of standard 0.15-mm black LDPE mulch, weed barrier fabric commonly used in landscapes placed under LDPE mulch, and Tyvek Home Wrap placed under LDPE mulch suppressed nutsedge emergence. In 1 yr, the size of strawberry plants grown with weed barrier fabric was reduced 23% compared with the other treatments and the number of marketable fruit in the third month of harvest was reduced 20% compared with LDPE mulch alone, likely because inadequately cut planting holes in this barrier restricted plant growth. Estimated costs for barrier treatments ranged from $5,000 to $12,000 ha−1compared with estimated hand-weeding costs of up to $24,000 ha−1. In 2007 to 2008 barrier treatments reduced the number of wind-dispersed weeds that commonly land and germinate in strawberry planting holes 67% compared with LDPE mulch alone. Removing the barriers at the end of the two seasons revealed that nutsedge plants sprouted but failed to grow and produce new tubers under the barriers. This observation suggests that nutsedge-impermeable barriers may aid in depletion of the soil tuber bank and therefore can be an effective tool in managing nutsedge for the length of the growing season.

The Effect of Biobarrier® on Mycorrhizae in Oak and Sweetgum

The effect of Biobarrier® herbicide-impregnated barrier fabric (Reemay, Inc., P.O. Box 511, Old Hickory, TN 37138-3651) on mycorrhizae occurrence was assessed on established pin oak (Quercus palustris) and sweetgum (Liquidambar styraciflua) trees. Trenches were dug through 24 tree root systems, and in 12 of the root systems, trenches were lined with Biobarrier. Seventeen months later roots were collected from within and adjacent to the trenches. Microscopic examination revealed that ectomycorrhizae occurred on roots of all 12 oak trees, regardless of the presence or absence of the barrier fabric. Similarly, roots from all sweetgum trees, except for 1 control tree (no barrier fabric), had vesicular endomycorrhizae.

INHIBITION OF TAP ROOT ELONGATION IN CONTAINERS BY SIX DIFFERENT MATERIALS COATED WITH SPIN OUT™

Tap roots of two coarse rooted species, Nyssa sylvatica and Quercus acutissima, were subjected to six treatment materials which were cut to fit or placed on the bottom of a 7.61 container. Each treatment material (paint only, Styrofoam plug tray, 3M floor buffer mat, peat fiber sheet, stone and weed barrier fabric) was either painted with Spin Out™ of impregnated with Spin Out™ WP. Treatments that allowed the tap root to penetrate the material, i.e. weed barrier fabric, stone and 3M floor buffing mat, were more effective in controlling tap root elongation. The weed barrier fabric significantly reduced tap root length of Quercus acutissima and Nyssa sylvatica by 80% and 67% respectively compared to controls and by 65% and 53% respectively compared to the paint only treatment. In some cases the 3M and stone treatments were more effective than the weed barrier fabric but were impractical because of weight or expense.

Influence of Mulches on Weed Control, Soil pH, Soil Nitrogen Content, and Growth of Ligustrum japonicum

Abstract Four organic mulches, screened pinebark, hardwood (primarily oak), cypress and decorative pinebark nuggets, applied at depths of 0, 5, 10, and 15 cm (0, 2, 4, 6 in) with or without an inorganic weed barrier fabric, were tested in field and container studies to determine their effect on weed suppression, soil pH, soil nitrogen content, and growth of Ligustrum japonicum. Results indicated that mulch applied at shallower depths, in combination with a weed barrier, provided optimal weed control without tying up soil nitrogen or reducing plant growth. Coarser mulches out-performed finer-textured materials. Most effective weed control was obtained with decorative pinebark nuggets with weed barrier fabric at a 15 cm (6 in) depth of application when compared to unmulched controls. As the depth of mulch was increased, soil pH, soil nitrogen content, and visual rating of plant growth decreased. Mulches over 10 cm (4 in) deep tended to inhibit plant growth, although optimum depth was dependent on the mulch material used.