chapter2 flammability performanceproofof biocomposites

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Flammability performance ofbiocomposites

Maya Jacob John1, 2, 3

1CSIR Materials Science and Manufacturing, Polymers and Composites Competence Area, PortElizabeth, South Africa, 2Department of Chemistry, Faculty of Science, Nelson MandelaMetropolitan University, Port Elizabeth, South Africa, 3School of Mechanical, Industrial andAeronautical Engineering, University of the Witwatersrand, Johannesburg, South Africa

Chapter Outline2.1. Introduction 12.2. Flammability testing techniques 2

2.2.1. Cone calorimetry 22.2.2. Pyrolysis combustion flow calorimetry 32.2.3. Limiting oxygen index 42.2.4. Underwriters laboratories 94 (UL94) 42.2.5. Ohio State University heat release apparatus (OSU) 5

2.3. Case studies 52.3. 1 Biopolymers and biocomposites 52.3.2. Use of green flame retardants 12

2.4. Conclusions 14References 14

2.1 INTRODUCTIONBio-based composites are witnessing a growth in different industrial sectors,mainly ranging from construction to aerospace industries. This recent surge inthe use of biocomposites is motivated by factors such as depletion of and highcost of petroleum reserves, comparable technical properties of biocomposites,and the current shift toward environmentally friendly and sustainable materialswhich in turn is supported by the implementation of environmental legislationsuch as REACH Act (Registration, Evaluation, Authorization and Restrictionof Chemical substances) and other bio-based incentives.

Chapter 2

Green Composites for Automotive Applications, https://doi.org/10.1016/B978-0-08-102177-4.00002-1Copyright © 2019. 1

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2 Green Composites for Automotive Applications

Bio-based products have been mainly used as flexible and rigid packagingmaterials where stringent flammability measures did not always have to be met.As recent trends seem to dictate the growing use of biopolymers [like polylac-tic acid (PLA)] and biocomposites in the transportation and electronics sector,it has become very relevant to formulate strategies to improve flammability bythe use of flame retardants to meet the various industrial regulatory standardsof these sectors. A few examples of such regulatory measures include for aero-space applications; components used as interior panels must exhibit heat re-lease rates (total heat release and peak heat release) ≤ 65 kW/m2 when testedon a Ohio State University heat release apparatus. For the automotive sector,the Federal Motor Vehicle Safety standard 302 stipulates that horizontal burnrate of the samples must not exceed 102 mm/min.

There are four main families of flame retardant (FR) chemicals: inorganic,organophosphorus, nitrogen-based, and halogenated. There are synergists thatact in combination with the FRs (e.g., antimony trioxide, zinc borate). Manyof the traditional FRs, however, pose environmental/ecotoxicological threats,whether it is during manufacture, application, or combustion, or at end-of-lifedisposal. For example, antimony trioxide is a possible carcinogen and some ofbrominated and chlorinated FRs may form dioxins and furans on combustionor can be persistent, bioaccumulative, and/or toxic to humans, and this has ledto a market call for halogen-free FRs There is growing evidence that these FRscan accumulate in people and cause adverse health effects—hormonal imbal-ances, interference with reproductive systems, thyroid and metabolic function,and neurological development in infants and children—and this has resultedin restrictions like REACH being imposed. The full-scale implementation ofREACH will affect more than 3000 chemicals across a huge range of industrialand consumer products. Another legislative measure—the Stockholm Conven-tion on Persistent Organic Pollutants (POPs)—has banned the production anduse of 21 chemicals of which four are brominated FRs.

Consequently, new ways are being sought to find more environmentallyfriendly FRs or fire resistance systems. These include modifications to new in-organic-based FRs, the use of nanocomposites (e.g., nanoclays), and nontoxic“green-chemistry” solutions. Also, in the use of green/environmentally friendlyFRs the biodegradable nature of the biopolymers is retained.

2.2 FLAMMABILITY TESTING TECHNIQUES

2.2.1 Cone calorimetryCone calorimetry is one of the most common fire behavior tests used to studythe rate of heat released by materials exposed to radiant heat flux. Its principleis based on the measurement of decreasing oxygen concentration in the com-bustion gases of the sample that is subjected to a given heat flux (10–100 kW/

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m2). The analysis of combustion products and gaseous species can be per-formed by installation of a Fourier transform infrared (FTIR) spectrometer [1].

The most important parameter obtained from cone calorimetric testing isthe heat released per unit of time and surface area (heat release rate, HRR) ex-pressed in kW m−2. The fire properties of materials are assessed by studyingthe gradual development of HRR over time, that is, the value of its peak maxi-mum (PHRR) or HRR maximum. The calculation of HRR is based on Hugget-t's study on the estimation of HRR via oxygen consumption measurements [1a].This study concluded that most organic materials release an amount of heat thatis practically proportional to the amount of oxygen consumed while burning.The proportionality factor is constant from one material to another and is equalto 13.1 kJ g–1 consumed oxygen, with an accuracy of approximately 5%. Thetotal heat release (THR) [2] is obtained by integration of the HRR versus timecurve expressed in MJ m–2. Cone calorimetry, in addition to the aforementionedparameters, also provides information on time to ignition (TTI), time to flameout (TFO), mass loss rate, levels of oxygen, carbon monoxide, and carbon diox-ide, and total smoke released (TSR). Furthermore, it provides more detailed firecharacteristics, with HRR being the most widely used parameter for evaluatingthe fire properties.

2.2.2 Pyrolysis combustion flow calorimetryPyrolysis combustion flow calorimetry (PCFC) is a fire test method for evalu-ating the combustibility of milligram-sized samples [3]. It is also known as mi-croscale combustion calorimetry (MCC) and is now a standardized techniqueclassified as ASTM D7309-07. PCFC reproduces the solid state and gas phaseprocesses of flaming combustion in a nonflaming test. This is achieved by con-trolled pyrolysis of the sample in an inert gas stream followed by high temper-ature oxidation of the volatile pyrolysis products. The heat of combustion ofthe pyrolysis products is measured by the use of oxygen consumption calorime-try. This method combines the constant heating rate and flow characteristics ofthermal analysis (i.e., thermogravimetry) with the ability to determine the heatof combustion typical of oxygen bomb calorimetry. PCFC determines the heatrelease and heat release rate using an oxygen consumption method.

The heat release capacity is the maximum potential of the material to releasecombustion heat in a fire. From the above derivation, the heat release capacity(ηc) is a combination of material properties, and consequently, is itself a mater-ial property as measured in PCFC. The use of Heat release capacity (HRC) as ameasure of fire risk is based on the assumption that the maximum specific heatrelease rate at the decomposition temperature reached at constant heating ratecorrelates with the mass loss rate during pyrolysis in a fire characterized by atransient temperature gradient [4].

Flammability performance of biocomposites

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2.2.3 Limiting oxygen indexLimiting oxygen index (LOI) is the minimum concentration of oxygen in amixture of oxygen and nitrogen that is needed to support the flaming combus-tion of a material. It is expressed in volume percent (vol%). It was first in-troduced in 1966 by Fenimore and Martin and is used to indicate the relativeflammability of materials. It is standardized in the United States (ASTM D2863) and in France (NF T 51-071), as well as internationally (ISO 4589). Themethod involves placing a sample vertically within a controlled atmosphere andits top inflamed with a burner. LOI, the minimum concentration of oxygen ina mixture of oxygen and nitrogen that either maintains flame combustion of amaterial for 3 min or consumes a length of 5 cm of a sample, is expressed as:

(2.1)

where [O2] and [N2] are the concentrations of oxygen and nitrogen gases, re-spectively.

Materials with LOI values less than 21% are classified as combustible, butthose with LOI greater than 21 are classed as self-extinguishing since theircombustion cannot be sustained at ambient temperature without an external en-ergy contribution. Materials with a high LOI value generally exhibit a betterFR property. This method remains one of the most important screening andquality control tools in the plastics industry to characterize both the ignitabil-ity and flammability resistance. However, LOI measurements are taken at roomtemperature and LOI values decrease as temperature increases. This means thatself-extinguishing cannot be considered a fast rule, since materials with highLOI values at room temperature may burn without self-extinguishing under in-tense fire conditions. It should be noted that melting and dripping of a polymerduring the LOI test may cause a specimen to extinguish and thus give mislead-ing high LOI values. In addition, LOI has a limitation as a test for nanocompos-ites in that organomodified nanoclay–reinforced polymer nanocomposites ex-hibit decreased LOI values due to an increased flame spread rate over the sur-face of the specimen, while inside the material nanoclays form a barrier layerthat limits the propagation of fire [5]. The advantages of LOI are that it pro-vides a convenient, reproducible means of determining a numerical measure offlammability. Furthermore, the test equipment is inexpensive and only a smallsample size is required for testing.

2.2.4 Underwriters laboratories 94 (UL94)UL 94 is a set of tests approved by Underwriters Laboratories Inc. as flametests for plastics materials for parts in devices and appliances. It includes arange of tests such as small and large flame vertical (V) tests, horizontal (H)

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tests for bulk and foamed materials, as well as radiant panel flame spread test.The commonly used test is UL 94V in terms of practice and usage. It measuresignitability and flame spread of vertical bulk materials exposed to small flame.It is equivalent to international standard IEC 60695-11-10 (Test method B) forsmall flames (50W) and ASTM D3801-10 [6]. The UL 94 test is widely usedboth in industry and academic research centers. It is intended to meet industrialrequirements, as well as classify polymeric materials hierarchically. The infor-mation obtained remains limited due to its basic and unrefined character.

2.2.5 Ohio State University heat release apparatus (OSU)The OSU is a technique used to measure the RHR of materials and products ina forced flaming combustion. Both heat and smoke release are measured fromthe moment the specimen is injected into a controlled exposure chamber. Mea-surements are continued during the period of ignition and to such a time that thetest is terminated. Although the OSU heat release apparatus is a good tool forflammability testing, there are known limitations of this test method [7]. Theheat and smoke release depend on several factors such as formation of surfacechar, formation of adherent ash, sample thickness, and method of mounting.Heat release values are a function of the exposed tested area of the specimen.The test method is restricted to the specified specimen size of materials, prod-ucts, or assemblies. In the case of products, the test specimen (i.e., prototype) isrepresentative of the product in actual size. At very high specimen HRR, flam-ing above the stack is possible making the test invalid.

There is no established general relationship between HRR values obtainedfrom horizontally and vertically oriented specimens. Specimens that melt anddrip in a vertical position are tested horizontally and hence vertical testing re-mains a problem for testing thermoplastic materials in the OSU.

2.3 CASE STUDIES

2.3 1 Biopolymers and biocompositesThe different types of FRs and their use in natural fibers and natural fiber–re-inforced composites has been documented in detail by Mngomezulu and John[8]. Generally it has been seen that the methods of imparting fire resistance innatural fiber–reinforced composites has been through three main routes [9]:

• Chemically treating the natural fibers with suitable FRs;• Treating the matrix (petroleum-based/biopolymer) with suitable FR addi-

tives during melt compounding stage;• Use of FR coatings on the molded natural fiber composite


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The choice of the FR depends upon the type of matrix polymer and pro-cessing technique used. In the case of natural fibers, commonly used FRs in-clude phosphorus and nitrogen-based systems, which function in the condensedphase and promote char formation by converting fiber structure into char andreduce fuel formation. The most commonly used FRs for thermoplastic poly-mers are metal hydroxides (aluminium hydroxide/magnesium hydroxide), ex-pandable graphite, ammonium polyphosphate, intumescent systems, and nan-oclays. Metal hydroxides act by undergoing exothermic reactions at elevatedtemperatures releasing vapor which retards the fire-forming reactions. Metalhydroxides need to be used at high loadings and usually has an adverse effecton mechanical properties. Phosphate-based systems interfere with polymer de-composition and promote char formation. FR coatings act as a barrier coatingand are more often ceramic or intumescent-based. Intumescent coatings uponexposure to fire form a carbonaceous layer which acts as a thermal barrier andprotects the underlying polymer system.

In recent times, the use of nanofillers in PLA has been of particular inter-est as researchers have found that such nanocomposites exhibit improved me-chanical properties at low loadings (3%–5%) along with increased flame resis-tance [10]. Addition of clay has been shown to reduce the peak heat release rate(PHRR) for PLA-based nanocomposites [11]. A decrease or increase in smokeproduction has also been observed. It has been proposed that when the poly-mer matrix is exposed to heat, the clay platelets migrate to the surface provid-ing a protective layer that delays gasification of the layer below. The clays alsoform a carbonaceous-silicate char which acts as a heat barrier, increasing ther-mal stability, and as a physical barrier to mass transport of oxygen and volatileproducts.

Solarski et al. investigated the flammability properties of melt-spun PLA/montmorillonite multifilament nanocomposite fibers using the cone calorime-ter [12]. They found a large (38%) decrease in the PHRR of the nanocompos-ites when compared to the pure PLA. Tensile strength and Young's modulus,however, decreased upon addition of clay. In addition to clay, multiwalled car-bon nanotubes (MWCNTs) have also been used in PLA but limited enhance-ment was observed as MWCNTs were not uniformly dispersed in PLA [13].Another nanofiller that has potential is expanded graphite (EG) which when in-corporated in PLA reduced the PHRR by 30% when compared to virgin PLA[14]. The use of natural halloysite as effective green FRRRs for thermoplasticcompounds was presented by Dharia and Zetoun [15].

Although PLA nanocomposites exhibit lower flammability properties interms of cone calorimetry, they often fail in other flammability tests (limit-ing oxygen index and UL-94) [16]. The fire resistance of the nanocompositecan, however, be improved by combining the nanofiller with conventional FRs.When using nanofillers, the properties achieved depend not only on the prop

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erties of the nanofiller and polymer but also on interfacial characteristics andthe method of preparation. Layered silicate nanocomposites, for example, re-sult only when an intercalated or exfoliated structure is formed. An intercalatednanocomposite is one in which the polymer chains are inserted into the layeredsilicate structure in a crystallographically regular fashion. When the individualsilicate layers are separated in a continuous polymer matrix, an exfoliated struc-ture is obtained. When the polymer is unable to intercalate between the layeredsilicates, phase separation occurs and the properties remain the same as that fora traditional microcomposite. For particle— or fibrous—reinforced nanocom-posites the dispersion and nanofiller-polymer interface is crucial in determin-ing the properties of the material. Uniform dispersion is usually attained bychemical modification of nanofillers to enhance the interfacial adhesion be-tween the nanofillers and polymer matrix. In a recent study, PLA containingmelamine grafted MWCNTs were found to exhibit a 28% reduction in PHRR.This was attributed to high level of dispersion in treated MWCNTs-reinforcedPLA when compared to unmodified systems. Another interesting observationwas the formation of a compact and cohesive char for the functionalized MW-CNT-reinforced PLA while unmodified PLA exhibited islands of char devoidof any cohesion [17].

The use of nanoclay (C30 B) and polylactic acid grafted glycidyl methacry-late (PLA-g-GMA) on flammability properties of silane-treated bananafiber–reinforced PLA composites was investigated by Sajna et al. [18] Flamma-bility properties measured by UL-94 horizontal burning test and cone calorime-try showed that the PHRR reduced by 22.6% in the presence of nanoclay (Fig.2.1). This was attributed to the fact that nanoclay accelerated the char forma-tion and hence could reduce the flammability of PLA samples.

Another group of FRs commonly used for natural fiber composites arethe inorganic hydroxides. In a recent study, Mg (OH)2 and Al (OH)3 wereused to improve the fire resistance of sisal [19] and saw-dust [20] –rein-forced polypropylene composites. However inorganic hydroxides have been re-ported to reduce the mechanical properties of composites and hence the useof Ca(OH)2 as a FR was studied by Zhao et al. [21]. for hemp-reinforcedpolypropylene composites. In this study, Ca (OH)2 was used to modify thehemp fiber surface and not incorporated in the compounding stage as in pre-vious studies. Fig. 2.2 shows the LOI values of the composites, and it canbe seen that the LOI values registered an increase indicating improved flameretardance, and this was attributed to the fact that Ca(OH)2 decomposed toform CaO and water which aided in fire resistance. The authors also observedthat addition of ammonium polyphosphate (APP) further improved flame retar-dance due to synergistic interaction between CaO and APP.

In a detailed study, Sypaseuth [22] observed that best flammability resultsare obtained when multicomponent FR systems are used. In the study dealingwith kenaf fiber–reinforced PLA composites, the synergistic effects of mul-ticomponent systems of expandable graphite with ammonium polyphosphate


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FIGURE 2.1 HRR graphs of compatibilized bionanocomposites.

FIGURE 2.2 Limiting oxygen index of the treated and untreated hemp and their reinforced com-posites.

and magnesium hydroxides with layered silicates were studied. It was observedthat for both systems, excellent flame retardance was obtained at low level ofFRs.

In another study [23] involving synergistic systems, ammonium polyphos-phate (APP) and distiller's dried grains with solubles (DDGS) as the naturalcharring agent was used for polylactic acid systems. The surfaces of bothAPP and DDGS were coated by degradable polymeric FR resorcinol di(phenyl

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phosphate) (RDP). The main observation of the study was that the limited oxy-gen index value of the biocomposites with loading of 15 wt% C—DDGS and15 wt% C—APP reached 32.0%, and a UL—94 V—0 was attained. The bio-composites also exhibited good mechanical properties with the tensile strengthof the samples being maintained at 57 MPa.

The effect of the FR APP on the properties of a range of natural fiber–re-inforced polybutylene succinate composites was investigated by Dorez et al.[24]. The natural fibers chosen in this study were cellulose, hemp, flax, sugar-cane, and bamboo and flammability was measured by PCFC and cone calori-metric testing. The main observations of this study were that the incorporationof fibers reduced the time to ignition in the composites but increased the charresidues (Fig. 2.3), which led to reduction of PHRR values. The authors sug-gest that the synergistic effect of the presence of APP and natural fibers resultsin decrease of flammability properties.

The use of glycerol phosphate and phosphorus-silane treatment on flaxfibers in flax-reinforced PLA/thermoplastic starch (TPS blends) was investi-gated by Bocz et al. [25]. The authors observed that the multifunctional ad

FIGURE 2.3 Residue of samples from cone calorimeter tests: (a) 90PBS10fl, (b) 85PBS15fl, (c)80PBS20fl, (d) 70PBS30fl.


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ditive system resulted in reduction of flammability properties by 40%. Thecomposites also exhibited well-balanced strength and stiffness values.

In an interesting study, the effect of biochar (carbonaceous material pro-duced when organic wastes are heated at high temperatures >500°C) on theproperties of polypropylene composites was investigated by Das et al. [26]. Theauthors observed that the both flame retardance and mechanical properties ofthe composites improved with the addition of biochar. With incorporation of35% biochar, the PHRR values were found to decrease by 54% (Fig. 2.4) andtime to ignition by 43%.This was attributed to the thermally stable biochar act-ing as an efficient barrier to transport of oxygen and reducing the flammability.

As an extension of the above study, the synergistic effect of biochar andwool on polypropylene composites was investigated by the same authors [27].Samples were prepared containing different ratios of biochar, wool, and APP.It was found that the incorporation of both biochar and wool fiber reduced thePHRR, smoke production as seen in Fig. 2.5 and resulted in improved LOI val-ues. Composites containing higher amount of wool exhibited higher LOI valuescompared to composites containing biochar. Another interesting observationwas that wool-containing composites exhibited minimal dripping of molten PPand negligible smoke production. This was attributed to the high fire resistanceand char forming ability of wool fibers.

Recently the researchers at the Council for Scientific and Industrial Re-search (CSIR), South Africa, have been involved in the development of woven

FIGURE 2.4 Flammability properties of biocomposites (cone calorimeter).

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FIGURE 2.5 Cone calorimeter results of neat PP and composites.

flax fiber–reinforced phenolic sandwich panels for use in aircraft as secondarystructures. The research work involved imparting an aqueous-based phosphateFR treatment on the flax fabric to ensure that the composite panels comply withFederal Aviation Administration (FAA) and AIRBUS regulations. In additionto the primary FR, the panels contained nonfibrous natural silicate fire resistantmaterial as well. The composite panels were reported to exhibit superior flam-mability, smoke, and toxicity properties for the aforementioned purposes [28].

In another study by the same group, researchers analyzed the aging andflammability behavior of woven flax fabric–reinforced phenolic composites. Itwas observed that the phosphate-based flame retardant treatment on the wovenflax fabric reduced the PHRR, SPR, and CO2 emission rates. Biocompositesbeing used in the transport sector are exposed to varying conditions of tem-perature and humidity and hence it is crucial to record the behavior of ma-terials after aging. In this study, after aging at high temperatures, the tensilestrength of both treated and untreated composites decreased, but the decreasewas most prominent in fire retardant–treated composites. This was attributed tothe degradation of the flame retardants when exposed to high temperature andhumidity. This further indicated that the selection of flame retardants is an im-portant criteria, especially for biocomposites to be used in advanced industrialapplications.

The commonly used conventional FRs in the automotive sector have beendescribed in Table 2.1.


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TABLE 2.1 Flame retardants used in automotive sector

Automotivecomponents Polymer Flame retardants (FRs)

Printed circuit board Epoxy/Phenolics Brominated FRs; Sulfonates

Housing and dashboard HIPS/ABS/PC-ABS alloys/PP

Brominated FRs

Wire and cables PP copolymers/EPR Brominated FRs

Battery casing PP Brominated FRs

Textile for seats Latex backcoating Brominated and phosphorus-based additives

Seats Flexible PUF Phosphorus-based additives

Connectors andunderhood parts

Polyamides Brominated FRs

Acoustic insulation XPE foam Brominated and mineral-based FRs

Thermal insulation Rigid PUF/XPE foam/Plasticized PVC

Phosphorus-based additives

Truck and boat covers Plasticized PVC Phosphorus-based additives

Door partition andinternal panels

PP and wood polymercomposites

Mineral and phosphorus-based FRs

Adapted from Fire protection for automotive and transportation. http://icl-ip.com/wp-content/uploads/2015/07/FR-Transportation-2012.pdf.

In a recent study, researchers developed bio-based FR panels for trucks andbuses from Solaris and Fiat. The biopolymers used were PHB (polyhydroxybu-tyrate) and PBS (polybutylene succinate), which were obtained from byprod-ucts from the cellulose production. Sandwich panels were manufactured fromnatural fiber–reinforced PHB and PBS and a cork core and had potential to beused in trains and vans [30].

2.3.2 Use of green flame retardantsGlobal chemical regulations are on the increase and these changes impact abroad range of materials, including FRs. FR–based regulations are importantto ensure fire safety in areas like electronics, automobiles, and furnishings.Currently some of the conventional FRs pose environmental/ecotoxicologicalthreats, whether it is during manufacture, application, or combustion, or atend-of-life disposal, and are subsequently under the threat of being banned.

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The emergence of stringent legislative measures (like REACH) and the desirefor sustainability are resulting in a focus on the need for characterizing environ-mental and human health impacts of all chemicals. In response to the regulatorychallenges, the research community has focused attention on the developmentof flame retardants that are safe, effective, in compliance with regulations, andare sustainable.

Some of the techniques used for imparting flame resistance by green flameretardants have been used for textile fabrics. The use of deoxyribonucleic acid(DNA) and chitosan as flame retardants through the layer-by-layer techniquefor cotton fabrics was investigated by Carosio et al. [31]. The authors observeda reduction of HRR by 40% during cone calorimetry tests and self-extinguish-ing characteristics during horizontal flammability tests. This was attributed tothe fact that DNA contains a precursor of phosphoric polyphosphoric acid, apolyhydric char source and an ammonia releasing base. The combination withchitosan promoted the formation of char which reduced the flammability of thesystem.

Another study elaborated on the novel use of chitosan-based FR (urea saltof chitosan phosphate [UPCS]) on the flammability properties of polyvinyl al-cohol (PVA). The authors observed a reduction of 42% in PHRRs upon theaddition of 20% FR. This was attributed to the fact that UPCS accelerated thedehydration action and the formation of char at low temperatures [32].

In an interesting study, the flame retardance behavior of alginate fibers wasstudied by Tian et al. [33]. The authors reported the LOI results which showedthat all zinc alginate fibers are intrinsically flame retardant, with LOI values ofover 27.0, as compared with about 24.5 for alginic acid fiber. The HRR and to-tal heat release values of zinc alginate fibers (obtained from cone calorimeter)were significantly less than those of alginic acid fiber, and decreased with in-creasing zinc ion content.

The use of lignin as a flame retardant for polybutylene succinate (PBS)composites was investigated by Ferry et al. [34]. Lignin possesses intrinsicproperties of high thermal stability, crosslinked chemical structure, and charforming ability indicating that it can be used as a FR additive. In this study,two types of lignin (alkali and organosolv) were used and the grafting of phos-phorus on lignin was also examined. It was observed that incorporation of 20weight% of alkali lignin reduced peak HRR by 50% (Fig. 2.6) and improvedcharring in the PBS system. The authors conclude that modified lignin can beused as an efficient bio-based FR.

Most of the bio-based FRs developed are either expensive or affect the me-chanical properties of the final product. To overcome this, in an H2020 on-going project on bio-based FRs for consumer electronics and automotive ap-plications, researchers are developing green FRs from a combination of a re-cently developed lignosulphonate flame retardant (LS-FR) and commercial am-monium polyphosphate (APP). LS-FR which is obtained as a byproduct ofpulp industry has been found to be an effective and bio-based FR which com


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FIGURE 2.6 HRR versus time curves from cone calorimeter test at 35 kW/m2 for the variousPBS-alkali lignin blends.

plies with fire resistant standards for the consumer electronics and automobilesectors, while maintaining adequate mechanical properties.

2.4 CONCLUSIONSThis chapter deals with studies on imparting flame retardance in biopolymersand biocomposites. The introduction section gives an overview of biocom-posites and stringent flammability requirements that needs to be met for bio-composites to be used in automotive and aerospace applications. The differ-ent flammability techniques and advantages and disadvantages of certain tech-niques have been outlined. Case studies based on flammability studies in fibers,biopolymers, and biocomposites and the use of green FRs have been presented.As seen from the case studies, the methods of imparting fire resistance has beenby treating the reinforcement (natural fibers) with suitable FRs, modifying thematrix polymers by use of FR additives during compounding, and use of FRcoatings. It can be inferred that FR characteristics is a prerequisite especially inadvanced industrial applications and hence novel strategies for development ofenvironmentally friendly FRs needs to be a focus area for researchers.

REFERENCES[1] Lind-

holm,

A.

Brink,

M.

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Chapter | 2 15

Hupa,

Cone

calorime-ter

–

a

tool

for

mea-sur-ing

heat

re-lease

rate,

2009.[1a] C. Hugget, Estimation of rate of heat release by means of oxygen consumption measurements, Fire and Materials, 4, 61-65,

1980.[2] I.S.

Wich-man,

Ma-te-r-ial

flam-ma-bil-ity,

com-bus-tion,

tox-i-c-ity

and

fire

haz-ard

in

trans-porta-tion,

Progress

in

En-ergy

and

Com-bus-tion

Sci-ence

29 (2003)

247–299.[3] A.B.

Mor-gan,

M.

Galaska,


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F


Mi-cro-com-bus-tion

calorime-try

as

a

tool

for

screen-ing

flame

re-tar-dancy

in

epoxy,

Poly-mers

for

Ad-vanced

Tech-nolo-gies

19 (2008)

530–546.[4] B.

Schar-tel,

K.H.

Pawlowski,

R.E.

Lyon,

Py-rol-y-sis

com-bus-tion

flow

calorime-ter:

a

tool

to

as-sess

flame

re-tarded

PC/ABS

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Chapter | 2 17

ma-te-ri-als?,

Ther-mochim-ica

Acta

462 (2007)

1–14.[5] S.

Chap-ple,

R.

Anand-ji-wala,

Flam-ma-bil-ity

of

nat-ural

fi-bre-re-in-forced

com-pos-ites

and

strate-gies

for

fire

re-tar-dancy:

a

re-view,

Jour-nal

of

Ther-mo-plas-tic

Com-pos-ite

Ma-te-ri-als

23 (2010)

871–893.


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[6] F.

Laoutid,

L.

Bon-naud,

M.

Alexan-dre,

J.-M.

JLopez-Cuesta,

P.

Dubois,

New

prospects

in

flame

re-tar-dant

poly-mer

ma-te-ri-als:

from

fun-da-men-tals

to

nanocom-pos-ites,

Ma-te-ri-als

Sci-ence

and

En-gi-neer-ing

R

63 (2009)

100–125.[7] M.M.

Hirschler,

Use

of

heat

re-lease

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Chapter | 2 19

mea-sure-ments

and/or

fire

haz-ard

as-sess-ment

in

codes

and

stan-dards

in

the

USA,

In:

Fire

risk

&

haz-ard

as-sess-ment

sym-po-sium,

June

28–30,

2000,

Na-tional

Fire

Pro-tec-tion

Re-search

Foun-da-tion,

At-lantic

City,

NJ,

2000.[8] M.E.

Mn-gomezulu,

M.J.


UNCO

RREC

TED

PROO

F


John,

V.

Ja-cobs,

A.S.

Luyt,

Re-view

on

flam-ma-bil-ity

of

biofi-bres

and

bio-com-pos-ites,

Car-bo-hy-drate

Poly-mers

111 (2014)

149–182.[9] B.K.

Kan-dola,

Flame

re-tar-dant

char-ac-ter-is-tics

of

nat-ural

fi-bre

com-pos-ites,

nat-ural

poly-mers,

vol.

1

UNCO

RREC

TED

PROO

F

Chapter | 2 21

com-pos-ites,

RSC

Pub-lish-ing,

2012.[10] M.

Alexan-dre,

P.

Dubois,

Poly-mer-lay-ered

sil-i-cate

nanocom-pos-ites:

prepa-ra-tion,

prop-er-ties

and

uses

of

a

new

class

of

ma-te-ri-als,

Ma-te-ri-als

Sci-ence

and

En-gi-neer-ing

28 (2000)

1–63.[11] J.W.

Gilman,

C.L.

Jack-son,

A.B.

Mor-gan,

R.


UNCO

RREC

TED

PROO

F


Har-ris,

E.

Ma-nias,

E.P.

Gi-an-nelis,

M.

Wuthenow,

D.

Hilton,

S.H.

Phillips,

Flam-ma-bil-ity

prop-er-ties

of

poly-mer-lay-ered-sil-i-cate

nanocom-pos-ites.

Polypropy-lene

and

poly-styrene

nanocom-pos-ites,

Chem

Mater

12 (1866–1873)

2000.[12] S.

So-larski,

F.

Mahjoubi,

M.

Fer-reira,

E.

De-vaux,

P.

Bachelet,

UNCO

RREC

TED

PROO

F

Chapter | 2 23

S.

Bour-bigot,

R.

De-lo-bel,

P.

Coszach,

M.

Mu-rariu,

A.

Da

Silva

Fer-reira,

M.

Alexan-dre,

P.

Degee,

P.

Dubois,

(Plas-ti-cized)

poly-lac-tide/clay

nanocom-pos-ite

tex-tile:

ther-mal,

me-chan-i-cal,

shrink-age

and

fire

prop-er-ties,

Jour-nal

of

Ma-te-r-ial

Sci-ence

42 (2007)


UNCO

RREC

TED

PROO

F


5105–5117.[13] M.

Mu-rariu,

L.

Bon-naud,

P.

Yoann,

G.

Fontaine,

S.

Bour-bigot,

P.

Dubois,

The

pro-duc-tion

and

prop-er-ties

of

poly-lac-tide

com-pos-ites

filled

with

ex-panded

graphite,

Poly-mer

Degra-da-tion

and

Sta-bil-ity

95 (2010)

374–381.[14] S.

Bour-bigot,

G.

Fontaine,

S.

UNCO

RREC

TED

PROO

F

Chapter | 2 25

Duquesne,

R.

De-lo-bel,

PLA

nanocom-pos-ites:

quan-tifi-ca-tion

of

clay

nan-odis-per-sion

and

re-ac-tion

to

fire,

In-ter-na-tional

Jour-nal

of

Nan-otech-nol-ogy

5 (2008)

683–692.[15] Dharia

A.,

Ze-toun

A.,

AMI

Flame

Re-tar-dants

in

Plas-tics,http://appliedminerals.


UNCO

RREC

TED

PROO

F


tempwebpage.com/images/uploads/eventspresentations/Applied_Minerals_-_FR_JUNE14.pdf.

[16] S.

Sinha

Ray,

K.

Ya-mada,

M.

Okam-ato,

Y.

Fu-ji-moto,

K.

Ueda,

New

poly-lac-tide/lay-ered

sil-i-cate

nanocom-pos-ites.

5.

De-sign-ing

of

UNCO

RREC

TED

PROO

F

Chapter | 2 27

ma-te-ri-als

with

de-sired

prop-er-ties,

Poly-mer

44 (2003)

6633–6646.[17] S.

Bour-bigot,

G.

Fontaine,

A.

Gal-los,

C.

Ger-ard,

S.

Bel-layer,

In:

C.A.

Wilkie,

A.B.

Mor-gan,

G.L.

Nel-son

(Eds.),

Fire

and

poly-mers

V

–

Ma-te-ri-als

and

con-cepts

for

fire

re-tar-dancy,


UNCO

RREC

TED

PROO

F


vol.

1013,

Amer-i-can

Chem-i-cal

So-ci-ety,

Wash-ing-ton,

DC,

2009, pp.

25–34.[18] S.

V.P.,

S.

Mo-hanty,

S.K.

Nayak,

In-flu-ence

of

nan-oclay

and

graft

copoly-mer

on

the

ther-mal

and

flam-ma-bil-ity

prop-er-ties

of

poly-lac-tic

acid/ba-nana

fi-bre

bio-com

UNCO

RREC

TED

PROO

F

Chapter | 2 29

-pos-ites,

Jour-nal

of

Vinyl

and

Ad-di-tive

Tech-nol-ogy

(23,

2017)

https://doi.org/10.10002/vnl.21556.

[19] N.

Sup-pakarn,

K.

Jarukumjorn,

Me-chan-i-cal

prop-er-ties

and

flam-ma-bil-ity

of

sisal/PP

com-pos-ites:

ef-fect

of

flame


UNCO

RREC

TED

PROO

F


re-tar-dant

type

and

con-tent,

Com-pos-ites

Part

B

40 (2009)

613–618.[20] M.

Sain,

S.H.

Par,

F.

Suhara,

S.

Law,

Flame

re-tar-dant

and

me-chan-i-cal

prop-er-ties

of

nat-ural

fi-bre–PP

com-pos-ites

con-tain-ing

mag-ne-sium

hy-drox-ide,

Poly-mer

Degra-da-tion

and

Sta-bil-ity

UNCO

RREC

TED

PROO

F

Chapter | 2 31

83 (2004)

363–367.[21] W.J.

Zhao,

Q.X.

Hu,

N.N.

Zhang,

Y.C.

Wei,

Q.

Zhao,

Y.M.

Zhang,

J.B.

Dong,

Z.Y.

Sun,

B.J.

Liu,

L.

Li,

W.

Hu,

In

situ

in-or-ganic

flame

re-tar-dant

mod-i-fied

hemp

and

its

polypropy-lene

com-pos-ites,

RSC

Ad-vances

7 (2017)

32236–32245.


UNCO

RREC

TED

PROO

F


[22] F.D.

Sypaseuth,

E.

Gallo,

S.

Ciftci,

B.

Schar-tel,

Poly-lac-tic

acid

bio-com-pos-ites:

ap-proaches

to

a

com-pletely

green

flame

re-tarded

poly-mers,

E-Poly-mers

17 (2017)

449–462.[23] X.

Shi,

The

in-tu-mes-cent

flame-re-tar-dant

bio-com-pos-ites

of

poly(lac-tic

acid)

con-tain-ing

sur

UNCO

RREC

TED

PROO

F

Chapter | 2 33

-face-coated

am-mo-nium

polyphos-phate

and

dis-tiller's

dried

grains

with

sol-ubles

(DDGS),

Fire

and

Ma-te-ri-als

(2017)

1–8,

https://doi.org/10.1002/fam.2479.

[24] G.

Dorez,

A.

Taguet,

L.

Ferry,

J.M.

Lopez-Cuesta,

Ther-mal

and

fie

be


UNCO

RREC

TED

PROO

F


-hav-iour

of

nat-ural

fi-bres/PBS

bio-com-pos-ites,

Poly-mer

Degra-da-tion

and

Sta-bil-ity

98 (2013)

87–95.[25] K.

Bocz,

B.

Szol-noki,

A.

Marosi,

T.

Tabi,

M.

Wla-dyka-Przy-by-lak,

G.

Marosi,

Flax

fi-bre

re-in-forced

PLA/TPS

bio-com-pos-ites

flame

re

UNCO

RREC

TED

PROO

F

Chapter | 2 35

-tarded

with

mul-ti-func-tional

ad-di-tive

sys-tem,

Poly-mer

Degra-da-tion

and

Sta-bil-ity

106 (2014)

63–73.[26] O.

Das,

D.

Bhat-tacharyya,

D.

Hui,

K.-T.

Lau,

Me-chan-i-cal

and

flam-ma-bil-ity

char-ac-ter-i-sa-tions

of

biochar/polypropy-lene

bio-com-pos-ites,

Com-pos-ites

Part

B


UNCO

RREC

TED

PROO

F


106 (2016)

120–128.[27] O.

Das,

N.K.

Kim,

A.K.

Sarmah,

D.

Bhat-tacharya,

De-vel-op-ment

of

waste

based

biochar/wool

hy-brid

bio-com-pos-ites:

flam-ma-bil-ity

char-ac-ter-is-tics

and

me-chan-i-cal

prop-er-ties,

Jour-nal

of

Cleaner

Pro-duc-tion

144 (2017)

79–89.[28] R.

Anand-ji-wala,

UNCO

RREC

TED

PROO

F

Chapter | 2 37

S.A.

Chap-ple,

M.J.

John,

H.J.

Schelling,

W.,M.

Michaelis,

M.

Döcker,

A

flame-proofed

arte-fact

and

a

method

of

man-u-fac-ture

thereof,

WO

2013/084023

A1,

World

In-tel-lec-tual

Prop-erty

Or-ga-ni-za-tion,

In-ter-na-tional

Bu-reau,

2013.[29] Fire

pro-tec-tion

for

au-to


UNCO

RREC

TED

PROO

F


-mo-tive

and

trans-porta-tion.

http://icl-ip.com/wp-content/uploads/2015/07/FR-Transportation-2012.pdf.

[30] http://www.aimplas.net/blog/new-flame-retardant-and-biodegradable-panels-trucks-and-buses-wastes-paper-industry.

[31] F.

Caro-sio,

A.

Di

Bla-sio,

J.

Alongi,

G.

Malu-celli,

Green

DNA-based

flame

re

UNCO

RREC

TED

PROO

F

Chapter | 2 39

-tar-dant

coat-ings

as-sem-bled

through

layer

by

layer,

Poly-mer

54 (2013)

5148–5153.[32] S.

Hu,

L.

Song,

L.

Pan,

Y.

Hu,

Ef-fect

of

a

novel

chi-tosan-based

flame

re-tar-dant

on

ther-mal

and

flam-ma-bil-ity

prop-er-ties

of

polyvinyl

al-co-hol,

Jour-nal

of

Ther-mal

Analy-sis

and


UNCO

RREC

TED

PROO

F


Calorime-try

112 (2013)

859–864.[33] G.

Tian,

Q.

Ji,

D.

Xu,

L.

Tan,

F.

Quan,

Y.

Xia,

The

ef-fect

of

zinc

ion

con-tent

on

flame

re-tar-dance

and

ther-mal

degra-da-tion

of

al-gi-nate

fi-bres,

Fi-bres

and

Poly-mers

14 (2013)

767–771.[34] L.

Ferry,

G.

UNCO

RREC

TED

PROO

F

Chapter | 2 41

Dorez,

A.

Taguet,

B.

Otaza-gh-ine,

J.M.

Lopez-Cuesta,

Chem-i-cal

mod-i-fi-ca-tion

of

lignin

by

phos-pho-rus

mol-e-cules

to

im-prove

the

fire

be-hav-iour

of

pol-ubuty-lene

suc-ci-nate,

Poly-mer

Degra-da-tion

and

Sta-bil-ity

113 (2015)

143–235.


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