Fire Retardancy Behavior Research Articles

Thermal degradation and fire retardant behaviour of natural fibre reinforced polymeric composites- A comprehensive review

In this comprehensive review, we dive into the potential of natural fibre composites, tracing their historical use spanning three millennia and their recent incorporation into polymer matrices. Various natural fibres, including flax, hemp, jute, and more, have been explored as potential reinforcements due to their renewable nature and environmental appeal. Moreover, these fibers are gaining traction in industries such as automotive and packaging. Leveraging abundant agricultural waste such as, wheat husk, rice husk, straw, and hemp fibre into commercially viable fibre-reinforced polymer composites. A thorough summary is given in this article of the diverse array of natural fibers, their current research status, encompassing properties, processing techniques, filler materials on structural factors, thermogravimetric analysis, dynamic mechanical performance under thermal loading, fire retardant behaviour, cone calorimetric analysis and various other applications, all while referencing the latest developments in the field, exploring a sustainable future with natural fibre composites. Furthermore, the difficulties associated with natural fibre-reinforced composites, including their vulnerability to humidity, fire retardancy and compliance with fibre matrices, are examined. This paper summarizes the complex field of natural fibre composites and covers several thermal stability-related appearance.

Thermal degradation, visco-elastic and fire-retardant behavior of hybrid Cyrtostachys Renda/kenaf fiber-reinforced MWCNT-modified phenolic composites.

Natural fibers have emerged as a potential alternate to synthetic fibers, because of their excellent performance, biodegradability, renewability and sustainability. This research has focused on investigating the thermal, visco-elastic and fire-retardant properties of different hybrid Cytostachys Renda (CR)/kenaf fiber (K) (50/0; 35/ 15, 25/25, 15/ 35, 0/50)-reinforced MWCNT (multi-walled carbon nanotubes)-modified phenolic composites. The mass% of MWCNT-modified phenolic resin was maintained 50 mass% including 0.5 mass% of MWCNT. In order to achieve homogeneous dispersion ball milling process was employed to incorporate the MWCNT into phenolic resin (powder). Thermal results from thermogravimetric analysis and differential scanning calorimetric analysis revealed that the hybrid composites (35/15; 35 mass% CR and 15 mass% K) showed higher thermal stability among the composite samples. Visco-elastic results revealed that kenaf fiber-based MWCNT-modified composites (0/50; 0 mass% CR and 50 mass% K) exhibited higher storage and loss modulus due to high modulus kenaf fiber. Fire-retardant analysis (UL-94) showed that all the composite samples met H-B self-extinguishing rating and exhibited slow burning rate according to limiting oxygen index (LOI) test. However, (15/35; 15 mass% CR and 35 mass% K) hybrid composites showed the highest time to ignition, highest fire performance index, lowest total heat release rate, average mass loss rate, average fire growth rate index and maximum average rate of heat emission. Moreover, the smoke density of all hybrid composites was found to be less than 200 which meets the federal aviation regulations (FAR) 25.853d standard. Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) was carried out to select an optimal composite sample considering the thermal, visco-elastic and fire-retardant behaviors. Through TOPSIS analysis, the hybrid (15/35; 15 mass% CR and 35 mass% K) composite sample has been selected as an optimal composite which can be used for high-temperature aircraft and automotive applications.

Polyimide Copolymers and Nanocomposites: A Review of the Synergistic Effects of the Constituents on the Fire-Retardancy Behavior

Carbon-based polymer can catch fire when used as cathode material in batteries and supercapacitors, due to short circuiting. Polyimide is known to exhibit flame retardancy by forming char layer in condensed phase. The high char yield of polyimide is attributed to its aromatic nature and the existence of a donor–acceptor complex in its backbone. Fabrication of hybrid polyimide material can provide better protection against fire based on multiple fire-retardancy mechanisms. Nanocomposites generally show a significant enhancement in mechanical, electrical, and thermal properties. Nanoparticles, such as graphene and carbon nanotubes, can enhance flame retardancy in condensed phase by forming a dense char layer. Silicone-based materials can also provide fire retardancy in condensed phase by a similar mechanism as polyimide. However, some inorganic fire retardants, such as phosphazene, can enhance flame retardancy in gaseous phase by releasing flame inhibiting radicals. The flame inhibiting radicals generated by phosphazene are released into the gaseous phase during combustion. A hybrid system constituted of polyimide, silicone-based additives, and phosphazene would provide significant improvement in flame retardancy in both the condensed phase and gas phase. In this review, several flame-retardant polyimide-based systems are described. This review which focuses on the various combinations of polyimide and other candidate fire-retardant materials would shed light on the nature of an effective multifunctional flame-retardant hybrid materials.

Investigation on Moisture Absorption and Fire Retardant Behaviour of Glass Fiber, Jute Fiber and Hybrid Glass/Jute Fiber Reinforced with Epoxy/Polyester Resin made by Hand Layup and Vartm Technique

Investigation on Moisture Absorption and Fire Retardant Behaviour of Glass Fiber, Jute Fiber and Hybrid Glass/Jute Fiber Reinforced with Epoxy/Polyester Resin made by Hand Layup and Vartm Technique

Effect of melamine cyanurate on thermal and flame-retardant behaviour of chopped glass fibre reinforced polyphenylene ether/polystyrene/nylon-6

This paper deals with the effect of melamine cyanurate on the thermal and fire retardant behaviour of chopped glass fibre (40 wt.%) reinforced polyphenylene ether/polystyrene/nylon-6 (40/40/20 wt. %) which are processed in a twin screw co-rotating extruder. The composite specimens were fabricated by injection moulding. Addition of melamine cyanurate decreased the amount of toxic gases and organic volatile compounds, crystallinity, crystalline temperature and melt temperature but the same fire-retardant increased glass transition temperature and heat distortion temperature of the ternary alloy. Flame retardancy with V0 and V2 rating along with Limiting Oxygen Index 35% was observed in UL94 test for 5 wt. % and 10 wt. % addition of melamine cyanurate, respectively. Addition of melamine cyanurate increased tensile modulus and elongation at break but decreased the melt flow rate and the moisture content of the ternary alloy.

Application of UF adhesives containing unmodified and phosphate-modified cellulose microfibers in the manufacturing of particleboard composites

In recent years, the application of cellulose derivative materials as reinforcement in wood adhesives has attracted considerable attention. This study aimed to explore the characteristics of cellulose microfibers (CMF) and phosphorylated cellulose microfibers (P-CMF) successfully extracted from giant reed plant, and their potential effect as binders in the formulation of particleboard panels-based urea-formaldehyde (UF) adhesive. The influence of fiber content (5%, 7.5%, and 10%) on the mechanical and physical properties of the prepared composites were assessed. Moreover, the fire-retardant behaviour of panels containing the optimal amount of phosphate was evaluated to study phosphate groups' efficiency in improving the resistance character of the panels towards the fire. Results showed that the mechanical properties were improved by the addition of 7.5% of CMF and P-CMF. The physical and fire-retardant properties were found to be significantly enhanced for panels containing 7.5% of P-CMF as a result of the chemical phosphorylation.

Polymer grafted gibbsite nanoplatelets via direct initiator tethering and surface-initiated atom transfer radical polymerization

An efficient method for the preparation of polymer grafted gibbsite nanoplatelets (NPs) was proposed by direct preparation of initiator-tethered gibbsite (gibbsite-Br) NPs followed by surface-initiated atom transfer radical polymerization (SI-ATRP) to obtain gibbsite particle brushes. By adding portion of water-soluble solvent (e.g., alcohol), individual ATRP initiator-tethered gibbsite NPs were fabricated using 2-bromo-2-methylpropionic acid as a tetherable initiator avoiding the aggregation of gibbsite NPs which are ready for polymer grafting process. To verify the efficiency of the tethered initiator, various polymers grafted gibbsite NPs were fabricated by SI-ATRP. The results indicated that initiator anchored gibbsite NPs and various gibbsite-g-polymers (e.g., gibbsite-g-poly2-(dimethylamino) ethyl methacrylate, gibbsite-g-polyacrylonitrile, gibbsite-g-polymethyl methacrylate) were synthesized successfully. The thermal stabilities of gibbsite-g-polymer hybrid materials have been enhanced significantly. Compared with PMMA matrix, the fire-retardant behavior of gibbsite-g-polymethyl methacrylate was strengthened due to the incorporation of gibbsite NPs. This work proposed a versatile and convenient method for producing initiator-immobilized solid NPs and polymer grafts, which thereby enables promised properties of polymer hybrid materials depending on the orientation and interactions of particle brushes.

Fire Retardancy, Water Absorption, and Viscoelasticity of Borated Wood-Polycarbonate Biocomposites.

Demand for high-performance biocomposites is increasing due to their ease of processing, low environmental impact, and in-service performance. This study investigated the effect of boric acid modification of wood flour on polycarbonate (PC) wood composites’ thermal stability, fire retardancy, water absorption, and creep behavior. The composites’ fire retardancy increased with increasing wood flour content, and their char residue increased by 102.3% compared to that of pure PC. However, the water absorption of the resulting composites increased due to the hydroxyl groups of the wood flour. Wood flour also improved the composites’ anti-creep properties. The excellent fire retardancy and anti-creep properties of wood–PC composites expand their use in the construction sector.

Heat of Decomposition and Fire Retardant Behavior of Polyimide-Graphene Nanocomposites

Polyimide is a high-performance engineering polymer with outstanding thermomechanical properties. Because of its inherent fire-retardant properties, polyimide nanocomposite is an excellent material for packaging electronic devices, and it is an attractive electrode material for batteries and supercapacitors. The fire-retardant behavior of polyimide can be remarkably improved when polyimide is reinforced with multilayered graphene sheets. Differential scanning calorimetry and thermogravimetric analysis were used to study the heat of decomposition and gravimetric decomposition rate, respectively, of polyimide-graphene nanocomposites. Polyimide/graphene nanocomposites containing 10, 20, 30, 40, and 50 wt.% of multilayered graphene sheets were heated at a rate of 10 and 30 °C/min in air and in nitrogen atmosphere, respectively. The rate of mass loss was found to remarkably decrease by up to 198% for nanocomposites containing 50 wt.% of graphene. The enthalpy change resulting from the decomposition of the imide ring was found to decrease by 1166% in nitrogen atmosphere, indicating the outstanding heat-shielding properties of multilayered graphene sheets due to their high thermal conductivity. Graphene sheets are believed to form a continuous carbonaceous char layer that protects the imide ring against decomposition, hence decreasing initial mass loss. The enthalpy changes due to combustion, obtained from differential scanning calorimetry, were used to calculate the theoretical heat release rates, a major parameter in the determination of flammability of polymers. The heat release rate decreased by 62% for composites containing 10 wt.% of graphene compared to the neat polyimide matrix. Polyimide has a relatively lower heat of combustion as compared with graphene. However, graphene significantly decreases the mass loss rates of polyimide. The combined interaction of graphene and polyimide led to an overall decrease in the heat release rate. It is noted that both mass loss rate and heat of combustion are important factors that contribute to the rate of heat released.

Magnetic hydroxyapatite nanocomposites: The advances from synthesis to biomedical applications

Nanoscale materials continue to amaze researchers due to their fascinating versatile properties. One such inspiring development in nanomaterials is the design of the nanocomposite materials for multifunctional purposes from energy storage to biomedical applications. Magnetic hydroxyapatite [MHAp] nanoparticles have achieved considerable attention during the last two decades and possess exceptional prospects in the field of nanomedicine with improved multi-therapeutic approaches. The progress from controlled fabrication to advanced applications of MHAp nanocomposites is still in its infancy and few efforts have been devoted to this cause. The hybrid structure of MHAp is anticipated to be an auspicious platform for biomedical applications particularly in cancer theranostics because of good stability and biocompatibility. In this review, recent exciting features in the development of MHAp nanocomposite and promising applications in controlled drug/gene delivery and magnetic hyperthermia treatment, tissue engineering and bone regeneration, antimicrobial activity, heavy metals and toxic dyes removal, fire retardant behaviour, biosensors and the development of contrast agents for magnetic resonance imaging are highlighted and explained in detail. In addition, this study provides a comprehensive assessment of the synthesis of MHAp nanocomposites by various preparation methods, the influence of reaction parameters on the morphology and structure-property relationships based on recent studies. Finally, novel perceptions are examined regarding the ability of MHAp nanoparticles to improve hybrid nanocarriers with homogeneous structure to enhance multifunctional biomedical applications.

Poly(diallyldimethylammonium) and polyphosphate polyelectrolyte complex as flame retardant for char-forming epoxy resins

The flame retardant poly(diallyldimethylammonium) and polyphosphate polyelectrolyte complex and the curing agent m-Phenylenediamine were blended into diglycidyl ether of bisphenol A (DGEBA)-type epoxy resin to prepare flame-retardant epoxy resin thermosets. The effects of poly(diallyldimethylammonium) and polyphosphate on fire retardancy and thermal degradation behavior of epoxy resins (EP)/poly(diallyldimethylammonium) and polyphosphate composites were tested by Limiting Oxygen Index, UL-94, cone calorimeter tests, and thermogravimetric analysis and compared with pure EP. The results showed that the Limiting Oxygen Index value of EP/poly(diallyldimethylammonium) and polyphosphate composite could reach 31.9%, and UL-94 V-0 rating at 10 wt% poly(diallyldimethylammonium) and polyphosphate loading. Meanwhile the cone calorimetry peak heat release rate and total heat release were reduced up to 55.2% and 21.8%, respectively; smoke production rate and total smoke production were also declined significantly, compared with those of pure epoxy resins. Poly(diallyldimethylammonium) and polyphosphate played a very good flame-retardant effect on epoxy resins.

Highly efficient fire retardant behavior, thermal stability, and physicomechanical properties of rigid polyurethane foam based on recycled poly(ethylene terephthalate)

AbstractThis study focused on the burning phenomena, thermal stability, and physicomechanical properties of polyurethane foam based on recycled poly(ethylene terephthalate) (RPUF) with and without halogen‐free flame retardants (FRs). Flammability behavior and associated mechanisms were studied by cone calorimetry, LOI, UL 94, FTIR, TGA, FE‐SEM, and XPS. The results of cone calorimeter testing indicate improved FR performance with notable reductions in peak heat release rate (~39.1%), peak CO production (~61.7%), and peak CO2production (~43.0%). LOI values significantly increase, up to 29.5–47.1%, in the presence of FRs, and V‐0 ratings are attained even at a rather low loading of FR (6.07 wt%). Meanwhile, the RPUF completely burns to the holder clamp with a low LOI value (17%), and it do not pass the UL94 HB standard. The addition of FRs notably improves the residual char of RPUF, indicating that FRs contributed to the formation of a barrier layer to protect RPUF during degradation. The comparison between experimentally determined TGA results and calculated values provides support for the effect of FRs on the thermal degradation behavior of RPUF. Sorption isotherm experiments of RPUF/FR systems show low moisture absorptivity and a weak hysteresis effect due to strong intermolecular bonds between RPUF and added FRs. The compression test, density, and morphology of foam samples are also discussed.

Mechanical, Fire Retardant, Water Absorption and Soil Biodegradation Properties of Poly(3-hydroxy-butyrate-co-3-valerate) Nanofilms

Biopolymers provide potential substitution to synthetic polymers derived from scarce petroleum materials which are not environmental friendly and biodegradable. However, there exists challenging or unanswered questions for biopolymers to be used in biomedical, film packaging, automobile, construction and commercial industries such as their mechanical performance, thermal and fire retardancy, and durability when exposed to water. In this study, we investigated one such potential biopolymer, poly(3-hydroxy-butyrate-co-3-valerate) (PHBV) for the aforementioned properties. At first, 0–15 wt% halloysite nanotubes (HNTs) was dispersed in PHBV polymer using ultrasonication process in presence of chloroform solvent. The solvent was then evaporated and PHBV/HNTs films were prepared by solution casting method. PHBV films without HNTs (neat) were also prepared for baseline comparison. Thermogravimetric analysis (TGA) and tensile tests were then performed to study the thermal and mechanical properties of these films. The horizontal burning test (HBT) was also carried out to investigate the fire retardancy behavior. Finally, the water absorption and soil biodegradability behavior of these composites were investigated by submerging the films in water and Alabama soil conditions. PHBV films with 3 wt% loading showed optimum enhancement in thermal stability and tensile properties. In contrast, films with 10–15 wt% HNTs loading showed superior fire-retardancy, better water resistance and faster soil degradation over neat counterpart.

Comparative Study of Jute, E-glass and Carbon Kevlar Fabric Reinforced Polypropylene Composite

In this experiment, three types of fabric such as jute, E-glass and carbon Kevlar were selected to manufacture composites taking polypropylene (PP) as matrix material. The objective of this study is to compare the examined properties such as tensile modulus (TM), elongation at break percentage (EB %), E-Modulus (EM) of jute, E-glass and carbon Kevlar fabric reinforced polypropylene composite. The properties of manufactured composite were evaluated experimentally using computerized UTM machine according to ASTM standards. Fourier transform infrared spectroscopy was used to identify the surface groups of the composites. Water absorption and fire retardant behavior of the composites were also performed. The results revealed that the tensile strength, E-Modulus and water absorption of carbon Kevlar composite were exhibited higher than the jute and E-glass fabric reinforced composites. Different scenario has observed for elongation percentage at break. The capacity of fire retardant was noticed higher in jute fabric composite than E-glass and carbon Kevlar.

Preparation of mineral bound particleboards with improved fire retardant and smoke suppression properties based on a mix of inorganic adhesive

Abstract An inorganic adhesive mix consisting of MgO, MgCl2, Na2SiO3, Na3PO4 was used to prepare mineral bound particleboard (mbPB) without formaldehyde emission and with excellent fire retardant and smoke suppression properties. The mechanical properties, interior microstructure, fire retardancy and smoke suppression behavior of the mbPB was investigated based on scanning electron microscopy (SEM) and cone calorimetric observations. The results showed that the presence of massive hydrates of the inorganic adhesive covers the mbPB particles, which are responsible for the positive effects. The effective smoke suppression was accompanied by an essential carbon monoxide (CO) and carbon dioxide (CO2) decrement in the gaseous effluents. The mbPBs are suitable as indoor material for wall, floor, and furniture as fire retardant and smoke suppressive materials.

Phenolic foams: A review of mechanical properties, fire resistance and new trends in phenol substitution

Phenolic foams (PF) have a combination of properties that make them attractive for a number of engineering applications such as insulation, lightening, energy absorption and fire protection. Phenolic foams exhibit excellent fire-retardant behaviour but have insufficient mechanical properties (e.g. fatigue, flexural properties and friability) for different applications in comparison to other foam materials. Hence, numerous studies have tried to improve these mechanical properties without deteriorating its excellent fire-retardant behaviour. Different approaches have been investigated, such as the addition of fibres and particles or the chemical modification of the PF base resin. This work will first briefly present generalities from resin synthesis to foam production. The main part will review the existing papers dealing with the improvement of the compressive and flexural strength as well as the friability. Moreover, evolution of the cell size with these mechanical properties will be presented, although there is no well-defined link between them. Then, the influence of these modifications on the fire-retardant behaviour of PF will be discussed. Finally, the last part will present work to substitute phenol from petroleum sources to environmental friendly sources.

Effect of fire retardants on mechanical properties of a green bio‐epoxy composite

ABSTRACTTo improve fire retardant behavior of bio‐epoxy resin, composites were prepared with three fire retardants (FRs); ammonium polyphosphate, aluminum trihydrate, and magnesium hydroxide. Fractured surfaces of prepared composites were observed with the scanning electron microscope (SEM). Tensile strength and Charpy toughness were evaluated and analyzed statistically using analysis of variance (ANOVA). Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) were used to determine the thermal stability. SEM analysis results revealed fractured surfaces were altered with addition of FRs. Adding FRs can be regarded as a decrease in tensile strength and toughness complemented by improved stiffness. ANOVA analysis showed FR/bio‐resin composites have a statistically significant loss in tensile strength, stiffness, elongation, and Charpy toughness. The DSC results showed the glass transition temperature was not affected significantly by adding FRs and ranged from 66 to 69 °C. TGA showed the initial, midway, and maximum decomposition temperatures for composites and their ability to form improved ash yields compared to pure resin. Aluminum trihydrate and Mg(OH)2 had higher T50 suggesting an increase in thermal stability compared to pure bio‐epoxy. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47398.

Short-lasting fire in partially and completely cured epoxy coatings containing expandable graphite and halloysite nanotube additives

Epoxy coatings containing halloysite nanotubes (HNTs) and expandable graphite (EG) are prepared and cured by the aid of an amine hardener varying the curing time and filler content, and then thermal degradation and fire retardancy of samples are experimentally and mechanistically discussed. The fire retardant actions of HNTs and EG were compared and interpreted in terms of the peak of Heat Release Rate (pHRR), Total Heat Release (THR), and Time-To-Ignition (TTI) collected on a cone calorimeter. Low and high levels of fillers were used to assess the effect of concentration of additives on fire retardancy behavior of epoxy coatings. Fire retardancy of coatings cured partially and completely at 100 °C was then correlated with cone calorimetry data to analyze the possibility of formation of intumescent layer on the surface of the epoxy, as evaluated by changes in pHRR and TTI values. Thermogravimetric analysis was also performed to give insight into thermal degradation of epoxy in the presence of HNTs and EG at low and high filler contents, where low concentration appeared useful to improve thermal stability of completely cured epoxy/HNTs samples, while high loading level caused enhancement in partially cured epoxy/EG composites thanks to thermal conductivity of EG platelets.

Preparation of Poly(phosphoric acid piperazine) and Its Application as an Effective Flame Retardant for Epoxy Resin

A phosphorus-nitrogen containing flame retardant additive of polyphosphoric acid piperazine, defined as PPAP, was synthesized by the salt-forming reaction between anhydrous piperazine and phosphoric acid, and the dehydration polymerization under heating in nitrogen atmosphere. Its chemical structure was well characterized by Fourier transform infrared (FTIR) spectroscopy, 13C and 31P solid-state nuclear magnetic resonance measurements. The synthesized PPAP and curing agent m-phenylenediamine were blended into epoxy resin (EP) to prepare flame retardant EP thermosets. The effects of PPAP on the fire retardancy and thermal degradation behavior of cured EP/PPAP composites were investigated by limiting oxygen index (LOI), vertical burning (UL-94), thermogravimetric analysis/infrared spectrometry (TG-IR) and cone calorimeter tests. The morphologies and chemical compositions of char residues for cured epoxy resin were investigated by scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS), respectively. The results demonstrated that the flame retardant EP thermosets successfully passed UL-94 V-0 flammability rating and the LOI value was as high as 30.8% when incorporating 5wt% PPAP into the EP thermosets. The TGA results indicated that the synthesized PPAP flame retardant additive possessed high thermal stability and excellent charring capability. Meanwhile, the incorporation of PPAP stimulated the epoxy resin matrix to decompose and charring ahead of time due to its catalytic decomposition effect, which led to a higher char yield at high temperature. The morphological structures and the analysis results of XPS for char residues of EP thermosets revealed that the introduction of PPAP benefited the formation of a sufficient, more compact and homogeneous char layer containing phosphorus-nitrogen flame retardant elements on the material surface during combustion. The formed char layer with high quality effectively prevented the heat transmission and diffusion, limited the production of combustible gases, and inhibited the emission of smoke, leading to the reduction of heat and smoke release.

A study on flammability and moisture absorption behavior of sisal/coir fiber reinforced hybrid composites

Cellulosic fiber reinforced Polymer Matrix Composites (PMC’s) are more frequently applied in construction industry and transportation, in which their flammability and water absorption behaviors are important. Fire resistance of cellulosic fiber reinforced composites is important parameter that often limits the application of composites in a given area. This work presents experimental results of a fire retardant behavior and moisture absorption behavior of different weight percentage (10, 20, 30, 40 and 50 wt. %) of sisal/coir fiber reinforced epoxy resin hybrid composites. Traditional cold pressing method was used to fabricate hybrid composites. Flammability behavior of the hybrid composite was studied by using vertical and horizontal burning rates as per standard UL-94. Addition of the cellulosic fiber increases the flammability since natural fiber supports fire. It proves as a bad flame retardant due to the generation of a surface layer during pyrolysis of the cellulosic fiber which exhibits poor fire retardant nature. This layer acts as supporter of fire, which spreads the heat from being transferred to the un-pyrolised material. The speed of flame is much faster in vertical burning position compared to horizontal burning position due to preheating of the specimen. Moisture absorption of sisal/coir fiber reinforced epoxy resin hybrid composites are studied according to ISO 62:1999 standard procedure. Absorption of moisture increases with increasing in the reinforcement weight percentage of cellulosic fiber in fabricated hybrid composite.