Effect of Zinc Borate (B2O6Zn3) on Microstructure and Properties of Chopped Basalt Fiber-Reinforced Epoxy-Based Composites

The effect of zinc borate (ZB) quantity on the mechanical and dielectric properties of 20 phr magnesium oxide/10 % rubbers (9/1 NR/ENR-50)/metallocene linear low-density polyethylene (mLLDPE) in the presence of N,N-m-phenylene bismaleimide (HVA-2) compatibilizer was investigated for wire and cable applications. With the increase in ZB loading, the tensile strength and the elongation-at-break of the composites decreased while the tensile modulus increased. In all composites, the strain-induced crystallization phenomenon at 200 % elongation was being observed in the stress–strain curves. Moreover, the dielectric strength, dielectric loss, permittivity and volume resistivity at frequency of 50 Hz were investigated. The permittivity of all composites increased with a rise in the voltage within the range of 1–5 kV. The loading of ZB in the composites improved the permittivity and volume resistivity as compared to the neat mLLDPE. The dielectric loss increased and 2 phr ZB composite displayed the highest dielectric loss among all other composites. On the other hand, the breakdown decreased with increasing ZB loading and the highest breakdown was observed in the 6 phr ZB composite. It was concluded that all composites are suitable for wire and cable application and the best result based on dielectric properties was observed in the 6 phr ZB composite.

Zinc borate (ZnB) has been used as a flame retardant, a smoke suppressant, and an antitracking agent in several applications. It may show synergistic effects with antimony oxide and metal hydroxides in fire retardant systems. In this work, the effect of ZnB on the flame retardancy of PET (poly(ethylene terephthalate)) woven fabrics was investigated. In order to provide the homogenous application of ZnB to the fabrics, the particle size of ZnB powders was reduced from 9 μm to submicron scale by wet-milling with zirconia balls followed by high shear fluid processing. ZnB dispersion was mixed with low-formaldehyde melamine resin based cross-linking agent and it was applied to PET fabrics by pad dry cure method. ZnB dispersion was then added in different ratios to alkyl phosphonate and organophosphorus compound based commercial flame retardant finishing agents and applied to the fabrics. The effect of zinc borate with phosphorus based flame retardant (FR) finishing agents was examined by cone calorimetry under a heat flux of 35 kW/m2, vertical flame test, and limit oxygen index. Thermogravimetric analysis was performed up to 800°C under N2flow. Test results show that zinc borate can be combined with the organophosphorus based commercial FR finishing agents. Zinc borate could not improve the flammability properties of PET fabrics significantly but decreased mean CO, total smoke release, and total smoke production values.

Exposure of hydrocarbon intumescent coatings to the UL1709 heating curve and furnace rheology: Effects of zinc borate on char properties

The effect of zinc borate (ZB) on the cure kinetics of commercial phenol–formaldehyde oriented strandboard adhesives was studied using differential scanning calorimetry. ZB caused a separation of the addition and condensation reactions for both face and core resin (CR) systems with lowered cure temperature for the addition reaction. For the face resin, ZB did not change its nth‐order curing mechanism, but retarded the whole cure reactions, and increased the reaction order and the activation energy. Compared with neat CR, the addition reaction of the CR/ZB mixture, which occurred at temperatures lower than 60°C, also followed an nth‐order reaction mechanism. The condensation reaction of the mixture was changed from an autocatalytic reaction to an nth‐order one with the reaction order of about 1. The proposed models fitted the experimental data well. Relationships among cure reaction conversion (i.e., cure degree), cure temperature, and cure time were predicted for various resin/ZB systems. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 3886–3894, 2006

ABSTRACTFriction materials based on several combinations of zinc borate (ZB) and fly ash (FA) were fabricated and characterized for their mechanical and tribological performance. The triboperformance of the friction materials was evaluated on a Chase friction testing machine according to the brake lining quality test procedure as per SAE J661. The composites were manufactured based on a nonasbestos organic-based friction material for an automotive brake system and contained typical ingredients for commercial brake friction materials. The composites had a fixed composition of 15 wt% resin, 15 wt% fibers, and 5 wt% friction additives. ZB and FA as fillers were added to the the raw materials mixture at a total fraction of 65 wt%. The results showed that ZB and FA contents have a significant influence on the mechanical and tribological properties of the friction composites. In particular, the composites containing 0–5 wt% ZB and 65–60 wt% FA showed better friction stability and improved fade resistance compared to those containing 10–35 wt% ZB and 55–30 wt% FA, whereas the composite with 5 wt% ZB and 60 wt% FA showed a maximum friction coefficient. On the other hand, the specific wear rate of the composites decreased with increasing ZB and decreasing FA contents. The morphologies of the worn surfaces as well as wear debris were analyzed by means of scanning electron microscopy.

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.

Effect of zinc borate and wood flour on thermal degradation and fire retardancy of Polyvinyl chloride (PVC) composites

In this work, zinc borate was used as a flame retardant in ethylene vinyl acetate/magnesium hydroxide or aluminum hydroxide flame-retardant formulations. High content zinc borate leads to significant improvements of flame retardancy through limiting oxygen index, UL-94 and cone calorimeter experiments. The protective char formation revealed significant structural modifications due to the presence of zinc borate. It was demonstrated that during polymer heating, aluminum hydroxide and magnesium hydroxide decomposed to Al2O3 and MgO which resulted an increase in ignition time. Moreover, formation of Al2O3 or MgO in situ from aluminum hydroxide or magnesium hydroxide during polymer combustion is the first event. Concurrently, zinc borate degraded and formed a vitreous protective coating, which yielded the substrate with an efficient char which acted as a physical barrier and a glassy cage for better protection of polymer substrate.

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.

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.

The effect of zinc borate (ZB) treatment on the mechanical and morphological properties of wood flour/polypropylene composites was investigated. Wood flour was first treated with ZB solution (1% w/w in ethanol-distilled water), followed by 24 hours of soaking on an unheated magnetic stirrer hot plate until relatively complete saturation was reached. Then, composites based on ZB-pretreated, ZB-treated-during-manufacturing, and untreated wood flour, polypropylene and coupling agent were made by melt compounding and then injection molding. The ZB treatment had no significant influence on mechanical properties of the composite with the exception of tensile strength. The composite made with ZB-pretreated wood flour exhibited the same mechanical properties as the composites made with ZB-in-process-treated wood flour; however there were statistically significant differences between flexural modulus and tensile strength of ZB-pretreated composites and ZB-in-process treated ones. Specimens containing the ZB showed lower flexural, tensile, and impact strength compared with the untreated specimens. However, the zinc borate treatments produced modest improvements in hardness performance. The SEM micrographs revealed that the outer surface of the wood fibers was coated by some crystalline deposits of zinc borate.

In this study, the flame retardancy contribution of zinc borate when used together with a traditional flame retardant (aluminum diethylphosphinate compound) was investigated for neat polyamide-6 and for 15 wt% short glass fiber reinforced composite. Melt mixing with twin-screw extrusion was the compounding method while injection and compression molding were the shaping methods of specimens. Three different flammability tests (limiting oxygen index, UL-94 vertical burning, mass loss calorimetry) indicated that many flame retardancy parameters could be improved significantly by replacing a certain amount of aluminum diethylphosphinate with zinc borate. For example, using aluminum diethylphosphinate alone resulted in only 32 % suppression in the value of the peak heat release rate for neat polyamide-6, while it was 82 % (more than two-fold) when used together with zinc borate. It was revealed by evolved gas analyses, char analyses, x-ray diffraction and thermogravimetry that the main contribution of zinc borate to aluminum diethylphosphinate was in terms of a barrier mechanism via formation of additional boron phosphate inorganic content in the barrier layer.

Effect of zinc borate as flame retardant formulation on some tropical woods

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

The effect of zincborate (ZB) and high-molecular-weight siloxane(SIL) on flame retardancy, mechanical, and thermal properties of aliphaticpolyketone (POK)-containing aluminum diethyl phosphinate (OF) wasinvestigated in this study. Ten wt % OF is sufficient to obtain V0rating according to the UL94 test. As the weight fraction of OF wasincreased, the flame retardancy properties and LOI values improved,while the tensile and impact properties decreased. To avoid the degradationin mechanical and impact properties as much as possible and obtainthe same and better flame retardancy properties, synergists such asSIL and ZB were used. Flame retardancy of POK-based composites wasdetermined by the limiting oxygen index (LOI) test, UL94 measurement,and cone calorimeter test. The additions of 1 wt % SIL and ZB havenot led to a considerable decrease in the tensile strength and impactproperties of POK-10OF. While ZB and SIL are very efficient in decreasingthe smoke density, ZB is more efficient than SIL in increasing theLOI value of the composite. The addition of 1, 2, and 4 wt % ZB andSIL synergists did not lower their UL94 ratings. Moreover, it canbe added that ZB is more efficient than SIL in decreasing the firegrowth rate (FIGRA) and maximum average rate of heat emission (MARHE)values. Using OF (10 wt %) and ZB (4 wt %), LOI values higher than32% and smoke density values lower than 150 were obtained.