Addition Of Zinc Borate Research Articles

Improving the flame retardancy and smoke suppression of flexible PVC by incorporating zinc borate‐modified diantimony trioxide

AbstractThe properties and structure of flexible PVC by incorporating zinc borate (ZB)‐modified diantimony trioxide (Sb2O3) were investigated. The results of flame retardancy and smoke suppression testing indicate that there was an obvious maximum Limited oxygen index (LOI) value of PVC/20 wt.% ZB–Sb2O3 composites reached 37.5% and passed the UL 94 V‐0 rating. An obvious synergistic effect between ZB and Sb2O3 was observed by LOI, SDR, and TG. Moreover, remarkable decreases in the smoke density were observed when ZB–Sb2O3 was incorporated into PVC. In addition, the tensile strength and elongation at break of PVC/ZB–Sb2O3 composites was higher than PVC/Sb2O3 composites, and this ameliorative effect was mainly arising from the ZB–Sb2O3 nanoparticles, which reduced the degree of fatal defects on PVC. The addition of ZB and Sb2O3 greatly increased the amount of residual char and apparently improved the mechanical properties of PVC composites. According to scanning electron microscopy photographs of residual char, after thermal decomposition, there were many fragments linked to the condensed phase and the compact char layer. Fourier transform infrared spectroscopy shows the residues char was composed of benzene ring, the flame retardants occurred and the condensed phase with significant interactions.

A Systematic Investigation on the Influence of Intumescent Flame Retardants on the Properties of Ethylene Vinyl Acetate (EVA)/Liner Low Density Polyethylene (LLDPE) Blends.

Because of their high filler loadings, commercial-grade clean flame-retardant materials have unstable mechanical properties. To address this issue, intumescent polymers can be used to develop clean flame retardants with very low levels of smoke and toxicity generation. An intumescent flame retardant (IFR) system composed of red phosphorus (RP), zinc borate (ZB), and a terpolymer of ethylene, butyl acrylate, and maleic anhydride (EBM) was used to prepare EVA (ethylene-vinyl acetate) and EVA/LLDPE (linear low-density polyethylene) composites; their mechanical and flammability properties were systematically investigated. The limiting oxygen index (LOI) of the EVA/LLDPE (as base material) composite containing RP and ZB mixed with nonhalogenated flame retardant, mainly magnesium hydroxide (MH) and coadditives, including processing aids and thermal stabilizers, was established. RP was found to have little effect on the tensile properties of EVA/LLDPE 118W/120 phr flame-retardant (MH + RP) composites. There was a minute difference in the effective trend of RP between tensile strength and elongation at break. Following the addition of ZB, the elongation at break of the composites gradually decreased with increasing RP content and then leveled off when the RP content was over 10 phr. Mechanical properties (elongation at break and tensile strength) can be best maintained at below 10 phr content of RP. The mechanical properties decreased with lower amounts of EBM content. In addition, flame retardancy increased when the EBM content decreased. The findings further revealed that MH and RP have poor compatibility, yielding poor mechanical properties. The LOI greatly increased with RP content, even though the total content of flame retardants (main + intumescent flame retardant) was the same in all formulations. Only over 5 phr RP content formulations passed V-0 of the UL-94 test. When under 5 phr, the RP content formulations did not pass V-0 of the UL-94 test.

Form-stable n-hexadecane/zinc borate composite phase change material for thermal energy storage applications in buildings

Phase change materials (PCMs), which have been in trend in recent years, are smart materials that allow energy to be stored in the form of latent heat in a specific temperature interval without losses. These materials have a wide range of uses and can be used extensively in building applications thus reducing the high energy costs. In this study, preparation of form-stable n-hexadecane (n-HD) /zinc borate (ZB) composite PCM for building applications was aimed. For this aim; n-HD as PCM was integrated with one-step impregnation into a porous polyHIPE composite matrix which is fabricated via polymerization reaction of styrene-divinyl benzene-based high internal phase emulsion in presence of sonochemically synthesized nano-sized ZB. The polyHIPE composite matrix and form-stable n-HD/ZB composite PCM were fully characterized by using physical, chemical and morphological methods namely Brunauer–Emmet–Teller surface area analysis, scanning electron microscopy, thermogravimetric analysis, Fourier-transform infrared spectroscopy, differential scanning calorimetry and polarized optical microscopy. Furthermore, heat storage rate of the obtained composite material was also increased with the addition of ZB besides its thermal stability and surface area. As a result, it can be said that a promising composite PCM was fabricated having 123 J/g thermal energy storage capacity that is suitable for application in buildings by means of its thermal and leakproof properties.

Effect of fiber size, cyclic moisture absorption and fungal decay on the durability of natural fiber composites

This research investigated the effect of different lignocellulosic fiber sizes and additives on the durability of wood plastic composites (WPCs) after water absorption/desorption. WPCs were prepared by blending wood flour (20, 80, 120 mesh) with polypropylene (PP). Polypropylene grafted maleic anhydride (MA) and zinc borate (ZB) were added in the formulation to improve the properties of the WPCs. Our results show that the fiber size significantly affects moisture absorption and that the damage accumulates during the cyclic absorption tests and affects the mechanical properties. WPCs with finer wood particulates absorbed less moisture. Adding MA helped maintain the modulus and reduced the moisture absorption of the WPCs during cyclic moisture absorption tests. Because ZB may dissolve in water during the moisture absorption experiment, the addition of ZB did not retard a fungal attack. Although cyclic moisture absorption reduced the mechanical properties, it did not enhance the fungal attack.

The synergistic flame retardancy of modified expandable graphite and metal hydroxides on HDPE/EVA composites

In this article, the flammable behaviors and synergistic effects of modified expanded graphite (MEG) with zinc borate (ZB) on flame-retardant high-density polyethylene/ethylene vinyl acetate (HDPE/EVA) composites containing magnesium hydroxide (MH) and aluminum hydroxide (ATH) are investigated by the Underwriters Laboratories-94 (UL-94) test, limiting oxygen index (LOI), cone calorimeter test (CCT), thermal gravimetric analysis (TGA), Fourier transform infrared (FTIR), differential scanning calorimetry, and tensile tests. The LOI, UL-94, and CCT results show that the synergistic effect of MEG and ZB can improve the flame retardancy of the composites. With the addition of ZB and MEG, the LOI value increases, and the UL-94 reaches the V-0 rating. The heat release rate and total heat release decrease, respectively. The data obtained from the TGA indicate that the synergistic effects of ZB with MEG increase the decomposition temperature when 2 phr ZB and 8 phr MEG are added into the composites. The data from FTIR show that HMEG8 and HMEG10 composites produce phosphate at high temperatures, which promotes the formation of stable and compact charred layer. All the results show that ZB and MEG have positive synergistic effects on HDPE/EVA composites containing MH and ATH. However, ZB and MEG play a negative role in the tensile properties of the HDPE/EVA composites.

Flame retardant effect of zinc borate in polyamide 6 containing aluminum hypophosphite

The effect of zinc borate (ZnB) on the thermal and flame retardant properties of polyamide 6 (PA 6) composites containing aluminum hypophosphite (AlHP) was examined. The properties of the composites were investigated using thermogravimetric analysis (TGA), limiting oxygen index (LOI), horizontal burning test (UL-94 HB), vertical burning test (UL-94 V), and mass loss calorimeter (MLC) studies. According to the thermal test results, ZnB improved the thermal stability of the AlHP. Chemical interaction was observed between ZnB and AlHP. According to the flammability test results, the highest LOI value of 26.7 is observed with the addition of 5 wt% ZnB. However, UL-94 V rating turned to burn to clamp owing to the ceasing of dripping. All samples were classified as HB in UL-94 HB test. According to the MLC results, the lower peak heat release rate (pHRR) and total heat evolved (THE) were obtained with the addition of ZnB. Fire performance index (FPI) greatly improved with the use of ZnB. ZnB showed adjuvant effect in the condensed phase via increasing the residue yield with compact structure.

Effect of Zinc Borate on Enhancing Flame Retardancy of Electron Beam Irradiated Alumina Trihydrate (ATH)/Acrylonitrile Butadiene Styrene (ABS) Composites

Abstract The purpose of this research was to investigate the effects of zinc borate loading level and electron beam irradiation dosages on flame retardancy and physico-mechanical properties of ATH-ABS blends. The increasing of irradiation dosage has gradually induced the gel content of all ATH-ABS blends by forming crosslinked networks. The addition of ATH and zinc borate has significantly increased the crystallinity of ABS blends as evident by the elimination of the hump on XRD curves. However, the application of lower electron beam irradiation dosages (≤150 kGy) has slightly decreased the crystallinity of 0 phr and 20 phr zinc borate added samples. The increasing zinc borate loading level from 5 phr to 20 phr has gradually increased the flame retardancy of non-irradiated samples by inducing char formation. Besides, the increasing of irradiation dosage has significantly improved the flame retardancy of all samples. The addition of zinc borate up to 15 phr has effectively increased the tensile strength of all ATH-ABS blends by enhancing the interfacial adhesion between the ATH particles and ABS matrix. The increment of irradiation dosages up to 250 kGy has gradually increased the tensile strength by introducing the formation of crosslinking networks in ABS matrix.

Synergistic Effect of Modified Expanded Graphite and Zinc Borate on the Flammability, Thermal Stability and Crystallization Behavior of LLDPE/EVA Composites with Mg(OH)2/Al(OH)3

In this work, modified expandable graphite (MEG) and zinc borate (ZB) are melt‐blended with metal hydroxide/aluminum hydroxide flame retardant linear low‐density polyethylene/ethylene vinyl acetate (LLDPE/EVA) blends. The synergistic effects of MEG with ZB on the flammability, thermal stability and crystallization behaviors of LLDPE/EVA composites are characterized and discussed by UL‐94 vertical burning, limiting oxygen index (LOI), thermogravimetric analysis, cone calorimeter test (CCT), carbon layer morphology, and differential scanning calorimetry (DSC). The addition of ZB and MEG apparently increases the LOI values and improves the UL‐94 rating of the flame retardant LLDPE/EVA composites. The data obtained from the CCT indicate that the heat release rate, the total heat release and the gas production rate of the flame retardant LLDPE/EVA composites decrease remarkably with increasing the MEG content and the residues of the composites increase to 38.2% from 2.7% of the LLDPE/EVA blends, which indicates that MEG enhances the thermal stability and layer carbon capacity of the composites. The DSC results describe that MEG can act as a nucleating agent to accelerate the crystallization rate of the flame retardant composites, but the crystallinity of polypropylene of the flame‐retardant composites firstly increases and then decreases with increasing the content of MEG. POLYM. COMPOS., 40:E687–E694, 2019. © 2018 Society of Plastics Engineers

Electron beam irradiation of zinc borate flame retardant containing acrylonite-butadiene-styrene (ABS) composites

The effects of electron beam radiation and zinc borate on the mechanico-physical properties and flame resistivity of magnesium hydroxide (MOH)- acrylonitrile butadiene styrene (ABS) composites have been investigated. The increasing of irradiation dosages has gradually improved the tensile strength and gel content of all samples by inducing the degree of crosslinking networks formed in ABS matrix. Analysis shows that higher amount of zinc borate is desirable to achieve promising tensile strength because zinc borate can attach into the interfaces between MOH particles and ABS matrix. Moreover, the addition of zinc borate could also retard the flammability of ABS as evidenced by LOI results. The crosslinking networks formed could improve fire resistance by reducing the melt dripping phenomenon. This is expected because the crosslinking networks can effectively minimize the oxygen gas to penetrate through the polymer structure to participate actively in the combustion activity.

Flame retardancy, antifungal efficacies, and physical–mechanical properties for wood/polymer composites containing zinc borate

SummaryThis work aimed to examine flame retardancy, antifungal performance and physical–mechanical properties for silane‐treated wood–polymer composites (WPCs) containing zinc borate (ZnB). ZnB with content from 0.0 to 7.0 wt% was added to WPCs, and silane‐treated wood contents were varied. The polymers used were poly(vinyl chloride) (PVC) and high‐density polyethylene (HDPE). The decay test was performed according to the European standard EN 113. Loweporus sp., a white‐rot fungus, was used for antifungal performance evaluation. Antifungal performance was observed to decrease with wood content. Incorporation of ZnB at 1.0 wt% significantly increased the antifungal performance of WPCs. ZnB content of greater than 1.0 wt% lowered the antifungal properties of WPCs. The results suggested that the wood/PVC composite exhibited better antifungal performance than the wood/HDPE composite. The addition of wood flour to PVC and HDPE decreased flame retardancy, whereas the incorporation of ZnB retained the flame retardancy. ZnB was found to be more appropriate for wood/PVC than wood/HDPE as a result of hydrogen chloride generated from the dehydrochlorination reaction of PVC. The results indicated that the addition of ZnB did not affect the physical‐mechanical properties of neat polymers and the composites. Copyright © 2016 John Wiley & Sons, Ltd.

Effects of organophosphorus and mineral based flame retardants on combustibility and mechanical performances of natural fiber reinforced composites

Purpose The study aimed to investigate epoxy composites reinforced with mechanical performances, thermal decomposition and ignitibility of natural fiber (NF) and doped with 5 wt.% of varying flame-retardant (FR) compounds. The incorporation of ammonium polyphosphate (APP) and zinc borate (ZB) showed improvement in modulus and elongation to break compared to the empty fruit bunch-filled epoxy (control). However, slightly lower tensile and impact strengths were recorded in all FR-containing composites. Design/methodology/approach Among the FR-loaded specimens, enhancement in flexural property was observed in composites with APP, whereas the addition of ZB and alumina trihydrate (ATH) resulted in the reduction of flexural strength. Thermogravimetric analysis results indicated that the introduction of APP and ATH negatively impacted the thermal degradation temperature (Td) of the NF-filled composites. Greater mass residue with FR-filled composites, where increment was in the range from 32-80 per cent compared to the control, was observed, with the greatest being the ZB-containing formulation. Vertical Bunsen burner experiment revealed that the addition of ZB and APP led to a zero dripping flame system, whereas such a phenomenon was absent in both the control and NF composites loaded with ATH. The bomb calorimeter results revealed that addition of NF into neat epoxy significantly enhanced the FR behavior of the composite, and the gross heat of combustion was greatly reduced when FRs were incorporated into the control sample. Findings Results from the current study concluded that non-halogenated FRs including APP, ZB and ATH were able to enhance the fire retardancy of EFB epoxy composite without significantly deteriorate the mechanical behaviors. Originality/value It can be shown from scanning electron microscopy micrographs that the fabrication technique produced composites with good interfacial adhesion between NF and epoxy matrix, and homogenous distribution of FRs were achieved.

Smoke suppression and synergistic flame retardancy properties of zinc borate and diantimony trioxide in epoxy-based intumescent fire-retardant coating

In this article, smoke suppression and synergistic flame retardancy properties of zinc borate (ZB) and diantimony trioxide (Sb2O3) in epoxy-based intumescent fire-retardant (IFR) coating were investigated based on cone calorimeter test, smoke density test, scanning electron microscopy, thermogravimetric and Fourier transform infrared spectroscopic analyses. The measurement results of the dynamic combustion and smoke production behaviors and static smoke production behaviors of these IFR coatings showed that the values of heat release rate, smoke production rate, smoke factor and fire growth index all decreased significantly with the addition of ZB and Sb2O3. At the same time, the specific optical densities were remarkably reduced due to the existence of ZB and Sb2O3. These attractive data clearly demonstrated that the ZB and Sb2O3 had a good effect on smoke suppression and synergistic flame retardancy of the IFR coating. Besides, the scanning electron microscopy and the infrared spectroscopic analyses during coating thermal degradation were also carried out to explore the outstanding synergistic smoke suppression and flame retardancy mechanism of ZB and Sb2O3. With the melt of ZB and Sb2O3, a lot of heat was absorbed, and then, the glassy protective layer associated with the graphite char would effectively retard heat and suppress smoke.

Effect of Ammonium Polyphosphate in Combination with Zinc Phosphate and Zinc Borate on Thermal Degradation and Flame Retardation of Polyamide 6/Clay Nanocomposites

In this paper, PA6/clay nanocomposites containing flame retardant additives such as ammonium polyphosphate (AP760), zinc phosphate and zinc borate were prepared by melt blending method. The resulting nanocomposites were characterized by X-ray diffraction and Fourier Transform Infrared spectroscopy (FTIR). X-ray diffraction patterns indicated the formation of intercalated structure in PA6 nanocomposites. FTIR analysis of residues obtained at 400°C revealed the formation of aromatic carbonaceous char and the presence of nitrile chain ends in the degradation products of PA6 composites. Thermogravimetric analysis and UL-94 test were performed to determine thermal stability and flammability of nanocomposites. Synergistic effects were observed on addition of zinc borate with AP760 in PA6/clay nanocomposites for increasing thermal stability by 38°C. The PA6/AP760 composite containing 20 wt% of AP760 without clay achieved flame retardancy with V-2 rating in UL-94 test.

Effect of Fumed Silica and Zinc Borate on the Thermal Property of ABS/Magnesium Hydroxide Flame Retardant Composites

Magnesium hydroxide (MH) has been used with polymers to make composites having flame retardancy as an environmental-friendly flame retardant. An attempt has been made in this direction, in order to enhance its flame retardant effectiveness. The synergistic effect of fumed silica (SiO2) and zinc borate (ZB) with MH in ABS based flame retardant composites was investigated with DSC. The endothermic effect of MH had little influence on the heat release reaction of ABS. The addition of ZB could not improve the thermal property of flame retarded ABS with MH. SiO2 or SiO2/ZB could significantly enhance the thermal property of the flame retarded ABS with MH based on the cooling effect of MH and the restraining effect of SiO2 or SiO2/ZB on the heat release reaction of SAN copolymer in ABS.

Flame retardant effect of boron compounds on red phosphorus containing epoxy resins

The effect of zinc borate (ZnB), boric acid (BA) and boric oxide (B 2 O 3 ) was studied on the flame retardant and thermal stability properties of epoxy resin containing red phosphorus (RP). The flame retardancy of epoxy based composites was investigated using limiting oxygen index (LOI), UL-94 standard, thermogravimetric analysis (TGA), mass loss calorimeter, scanning electron microscopy (SEM) and attenuated total reflectance – fourier-transform infrared spectroscopy (ATR-FTIR). The addition of 15 wt% RP based flame retardant additive increased the LOI value from 19.5 to 32.5 and V0 rating was obtained from UL-94 test. According to flammability properties, the maximum adjuvant effect was observed at ratio of 9:1 (RP:boron compounds) with the addition of ZnB and BA and at a ratio of 7:3 with the addition of B 2 O 3 . With the partial substitution of boron compounds for RP, lower heat release rate (HRR) and total heat evolved (THE) was obtained. According to fire performances, ZnB containing composite showed lowest HRR and THE values. The boron compounds showed beneficial effect by increasing char yield in the condensed phase.

Flame retardant high density polyethylene optimized by on-line ultrasound extrusion

The effect of on-line ultrasound application by a special static mixer die which promotes extensional flow simultaneously during the single screw extrusion process was thoroughly studied. The proportion of aluminum trihydroxide (ATH) used as flame retardant on high density polyethylene (HDPE) was optimized. The morphological, thermal, flammability, combustion, mechanical and rheological properties of the materials were investigated. The morphological study pointed out that this process is able to strongly reduce the size of ATH particles and improve their dispersion and distribution within the polymer matrix. The addition of zinc borate (ZB) at low concentration (namely 3 phr) showed its well-known synergistic effect in the thermal, oxygen index and fire combustion behavior. According to the UL94 standard, the rating for all materials tested changed from HB to V2, with respect to materials prepared without ultrasound; furthermore a rating V0 was achieved only with the addition of 2 phr organo-clay. Rheological results under simple and small amplitude oscillatory shear flow confirmed the enhanced particle dispersion and finer particle morphology evidenced by larger values of the moduli and by deviations from the semicircular shape observed in the Cole–Cole diagram. Mechanical properties such as Izod impact resistance, tensile strength, strain at break and tenacity were also improved by the on-line ultrasound process. In this work, the appropriate on-line ultrasound extrusion conditions to use the lowest ATH content (30 phr or 21.5 in wt%) were found, rendering HDPE optimized flame retardant materials with improved processability and mechanical properties.

Biological performance of wood–plastic composites containing zinc borate: Laboratory and 3-year field test results

Six different formulations of wood–plastic composites (WPC) fabricated from wood and polypropylene (PP) were tested in the laboratory against decay and termites and in a protected above-ground field test in southern Japan. Variables examined included comparisons of untreated and zinc borate (ZnB) incorporated formulations, wood content ratio, wood particle size and increased surface area via surface grooves (channels) to promote moisture infusion. A standard method originally designed to test durability of solid wood was modified for testing WPC. Wood decay fungi and Formosan subterranean termite activity in laboratory and field tests resulted in different mass losses, post-decay moisture contents and field test ratings depending on their wood and ZnB content. The results show that as wood content increased, mass losses also increased. Addition of ZnB at 1% (w/w) retention level significantly decreased mass losses of wood–plastic composite when exposed to laboratory decay and termite tests. The effects of surface grooves and wood particle size were less important, compared to wood particle content. All WPC tested were highly resistant to fungal decay under protected above-ground field conditions during 36months. Termite attack, on the other hand, started at earlier stage reducing mean ratings 1year after the installation.

Combustion Behaviour and Synergistic Effect of Zinc Borate and Microencapsulated Red Phosphorus with Magnesium Hydroxide in Flame-Retarded Polypropylene Composites

In this paper, the limiting oxygen index (LOI), Underwriters’ Laboratories-94 (UL-94) test, cone calorimeter test (CCT), and thermogravimetric analysis (TGA) were used to study the flame-retardant properties of polypropylene (PP) composites and the synergistic flame-retardant effects of zinc borate (ZB) and/or microencapsulated red phosphorus (MRP) with modified magnesium hydroxide (MH) on PP. The experimental results showed that the addition of ZB and MRP had a great effect on the flammability of the PP composites. The data obtained from the CCT indicated that the heat release rate (HRR), the effective heat of combustion (EHC), and the mass loss of the flame-retarded PP composites decreased markedly with increasing addition of ZB and/or MRP. The data obtained from the TGA curves indicated that the thermal stabilities of PP/MH/ZB and PP/MH/ZB/MRP composites were better than those of PP/MH composites.

Effects of zinc borate and microcapsulated red phosphorus on mechanical properties and flame retardancy of polypropylene/magnesium hydroxide composites

In this paper, the mechanical properties and flame retardancy of zinc borate (ZB) and microcapsulated red phosphorus (MRP) with modified magnesium hydroxide (MH) in flame-retardant polypropylene (PP) were studied by mechanical properties test, UL-94 test, and thermogravimetric analysis (TGA). The crystallization behaviors of the composites were investigated by differential scanning calorimetry (DSC) and polarizing optical microscopy (POM). The addition of ZB could improve tensile strength and elongation at break of PP/MH composite. The MRP powders had a little effect on the mechanical properties of the PP composites. DSC results showed the addition of ZB and MRP weakened the heterogeneous nucleation effect of MH on PP. The addition of ZB and MRP had a great effect on the flammability of the PP/MH/EG composites. The thermal stability of PP/MH/ZB and PP/MH/ZB/MRP composites was better than that of PP/MH composite.