Palm‐based bio‐composites hybridized with kaolinite

This study described the mechanical and thermal properties of hybrid bio‐composites from oil palm empty fruit bunch (EFB) fibers and kaolinite. The polyurethane (PU) used as matrix is formed by reacting palm kernel oil (PKO)‐based polyester with crude isocyanate. The blending ratio of PU to EFB fibers was fixed at 35 : 65 and kaolinite was added at 0, 5, 10, 15, and 20% (by weight). The occurrence of chemical interactions between the hydroxyl terminals in both fillers and the PU system was determined via FTIR spectroscopy. Hybrid bio‐composites showed improved stiffness, strength, and better water resistance with the addition of kaolinite to an extent. At 15% of kaolinite loading, maximum flexural and impact strengths were observed. The interaction between kaolinite with PU matrix and EFB fibers enhanced the mechanical properties of the bio‐composites, which was justified from the FTIR spectrum. However, over‐packing of kaolinite was observed at 20% kaolinite loading, which ruptured the cellular walls and degraded strength of the bio‐composites. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

A flame‐retardant composite foam: foaming polyurethane in melamine formaldehyde foam skeleton

A composite foam, polyurethane–melamine formaldehyde (PU/MF) foam, was prepared through foaming PU resins in the three‐dimensional netlike skeleton of MF foam. The chemical structure, morphology, cell size and distribution, flame retardancy, thermal properties and mechanical properties of such composite foam were systematically investigated. It was found that the PU/MF foam possessed better fire retardancy than pristine PU foam and achieved self‐extinguishment. Moreover, no melt dripping occurred due to the contribution of the carbonized MF skeleton network. In order to further improve the flame retardancy of the composite foam, a small amount of a phosphorus flame retardant (ammonium polyphosphate) and a char‐forming agent (pentaerythritol) were incorporated into the foam, together with the nitrogen‐rich MF, thus constituting an intumescent flame‐retardant (IFR) system. Owing to the IFR system, the flame‐retardant PU/MF foam can generate a large bulk of expanded char acting as an efficient shielding layer to hold back the diffusion of heat and oxygen. As a result, the flame‐retardant PU/MF foam achieved a higher limiting oxygen index of 31.2% and exhibited immediate self‐extinguishment. It exhibited significantly reduced peak heat release rate and total heat release, as well as higher char residual ratio compared to PU foam. Furthermore, the composite foam also showed obviously improved mechanical performance in comparison with PU foam. Overall, the present investigation provided a new approach for fabricating a polymer composite foam with satisfactory flame retardancy and good comprehensive properties. © 2018 Society of Chemical Industry     

A novel intumescent flame retardant with nanocellulose as charring agent and its flame retardancy in polyurethane foam

Ammonium polyphosphate (APP) is microencapsulated with nanocellulose and dicyandiamide‐formaldehyde using in situ polymerization and flocculation method. The presence of nanocellulose and dicyandiamide‐formaldehyde significantly affects the thermal behavior and flame retardancy of microencapsulated ammonium polyphosphate (DFNAPP). DFNAPP is much more stable from 524 to 637°C than that of APP because of the charred formation. Rigid polyurethane foam (PU) composites added DFNAPP obtain higher limiting oxygen index (LOI) values than that with the same loading of APP. Due to the presence of shell, experimental results indicate that DFNAPP obtains better compatibility and water resistance in PU matrix, resulting in the improved mechanical properties of the PU composites and the water durability. LOI value of PU/APP composite added 16.7 wt% additives has a decrement of 3.0% after water treatment. By comparison, that of PU/DFNAPP composite with the same loading of DFNAPP is only 0.3%. Compression strength of PU composite is increased from 195 kPa to 213 kPa when the DFNAPP (16.7 wt%) additive substitutes for APP (16.7 wt%). POLYM. COMPOS., 38:2762–2770, 2017. © 2015 Society of Plastics Engineers     

聚氨酯填充型泡沫混凝土复合材料的性能研究

将不同掺量聚氨酯（PU）加入泡沫混凝土（FC）,研究聚氨酯填充型泡沫混凝土（FC/PU）复合材料的性能。结果表明：随着PU掺量的增加,FC/PU复合材料的导热系数不断降低,阻燃性能变差。PU掺量为0～4%时,随着PU掺量的增加,FC/PU复合材料的浆体黏度逐渐降低,气孔特性变好,抗压强度不断增大。PU掺量超过4%时,FC/PU复合材料黏度开始增大,气孔特性变差,抗压强度逐渐降低。PU掺量为4%时,FC/PU复合材料的综合性能最优,与未掺入PU相比,黏度降低62.7%,气孔特性较好,抗压强度提高75.0%,导热系数降低18.7%,阻燃性能仍能达到A1级。     

Effect of filler‐to‐matrix blending ratio on the mechanical strength of palm‐based biocomposite boards

The effect of the blending ratio of a polyurethane matrix and oil‐palm empty fruit bunch (EFB) fibers on the mechanical properties of biocomposite boards has been studied. The PU matrix and EFB fibers were used at blending ratios of 25:75, 30:70 and 35:65 (by weight). The mechanical property of hardness was studied. The intention of this study was to produce fiberboard from a vegetable oil‐based polyester as the matrix and biomass from the palm oil industry, namely EFB. It was found that the blending ratio with a lower filler loading (35:65) gave higher impact and flexural strengths due to better fiber encapsulation which enhanced the fiber–matrix interfacial adhesion. Copyright © 2005 Society of Chemical Industry     

铝/磷/氮三元体系阻燃PU硬泡的制备与性能研究

以氢氧化铝、三聚氰胺和聚磷酸铵为阻燃剂制备了阻燃聚氨酯硬质泡沫,研究了添加氢氧化铝前后阻燃剂用量对聚氨酯(PU)硬泡的阻燃性能和力学性能的影响。结果表明,铝/磷/氮复配阻燃体系的阻燃效果优于磷/氮阻燃体系,阻燃剂总添加量达30份时,PU硬泡同时具备较好的阻燃性能和力学性能,氧指数为32,烟密度为74,平均燃烧时间为31 s,其压缩强度和拉伸强度分别为6.52 MPa和6.16 MPa。     

Reactive flame retardant with core‐shell structure and its flame retardancy in rigid polyurethane foam

With a shell of poly (methyl methacrylate‐co‐hydroxyl ethyl acrylate) (PMMA‐HA), microencapsulated ammonium polyphosphate (MHAPP) is prepared by in situ polymerization. The core‐shell structure of the reactive flame retardant (FR) is characterized by Fourier transform infrared (FTIR) and scanning electron microscopy/energy dispersive spectroscopy (SEM/EDS). The results of water leaching rate and water contact angle measurements show that ammonium polyphosphate (APP) is well coated by a hydrophobic shell. Due to the presence of active groups (–OH) and hydrophobic groups (–CH₃) in shell, MHAPP exhibits better compatibility, flame retardancy, and water resistance compared with neat ammonium polyphosphate (APP) in rigid polyurethane foam (PU). Compression strength of PU/MHAPP with suitable loading is higher than that of PU/APP and PU, the reason is that the active groups in shell can improve the compatibility of MHAPP in PU composite. From thermal stability and residue analysis, it can be seen that the presence of reactive flame retardant shows positive effect on thermal stability of PU composite at high temperature, results also indicate that MHAPP can promote the carbonization formation efficiency of PU composite during combustion process compared with APP. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42800.     

Polyurethane composites based on oil palm empty fruit bunches: Effect of isocyanate/hydroxyl ratio and chemical modification of empty fruit bunches with toluene diisocyanate and hexamethylene diisocyanate on mechanical properties

This study focuses on the effect of isocyanate (NCO)/hydroxyl (OH) group ratios and chemical modification of oil palm empty fruit bunches (EFBs) with toluene diisocyanate (TDI) and hexamethylene diisocyanate (HMDI) on the mechanical properties of EFB–polyurethane (PU) composites. The tensile, flexural, and impact properties are affected by the NCO/OH ratios. The tensile strengths, flexural strengths, and toughness increase as the NCO/OH increases; however, the modulus decreases. The reduction in the modulus is attributable to the increased flexibility of the PU linkages. Chemical modification of the EFBs increases the tensile strength, flexural strength, and toughness; however, the modulus is lowered as the percentage of treated EFB is increased. Impact strength results show that the strength increases as the NCO/OH ratio is increased. At NCO/OH ratios of 1.0 and 1.1, the composites with HMDI‐treated fibers exhibit higher impact strength than those with TDI‐treated and untreated fibers, respectively. This may be due to the longer and more flexible chain length of HMDI as compared to TDI, which enables the composites to absorb more energy before failure. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Preparation and characterization of surface‐modified ammonium polyphosphate and its effect on the flame retardancy of rigid polyurethane foam

A functional surface‐modification agent was synthesized via a reaction between hexachlorocyclotriphosphazene and γ‐aminopropyl triethoxysilane. Ammonium polyphosphate (APP) was modified with this agent and then incorporated into a rigid polyurethane foam (RPUF). Fourier transform infrared spectroscopy, ¹H‐NMR, and X‐ray photoelectron spectroscopy were used to characterize the modified ammonium polyphosphate (M‐APP). The results show that the dispersibility was improved and the particle size decreased after the modification. The limiting oxygen index and cone calorimetry test results show that M‐APP enhanced the flame‐retardant properties of RPUF. The peak heat‐release rate of polyurethane (PU)/20% M‐APP decreased by 51.18% compared with that of PU–APP. The scanning electron microscopy results illustrate that M‐APP facilitated the formation of intumescent and compact char. The excellent flame‐retardant performance of M‐APP resulted from the flame‐inhibition and barrier effects, which were attributed to the phosphazene group and the intumescent char, respectively. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45369.     

Physicomechanical,friction, and abrasion properties of EVA/PU blend foams foamed by supercritical nitrogen

Elastomer foams based on EVA, PU, and EVA/PU blends formulated for shoe‐sole applications were prepared by a supercritical N₂ batch foaming process and characterized for physicomechanical, friction and abrasion properties. The blending of EVA with PU was aimed for improving the friction and wear characteristics of the EVA based foams. All of the foams prepared showed spherical cells with closed‐cell morphology and the cell sizes varied with varying the EVA/PU blend ratio and CaCO₃ content of the foams. The properties such as hardness and resilience, friction coefficients and abrasion resistance improved for the EVA/PU blend foams compared to the EVA foam, but their compression set, tensile strength, and tear strength were inferior to the EVA foam. The incorporation of CaCO₃ filler increased density, hardness, tensile strength, and tear strength of the EVA/PU blend foams but decreased resilience, compression set, friction coefficients, and abrasion resistance. The improvement in friction coefficients and wear resistance obtained in the EVA/PU blend foams was significant for shoe‐sole applications. POLYM. ENG. SCI., 2017. © 2017 Society of Plastics Engineers     

The Effect of Glycol Type,Glycol Mixture,and Isocyanate/Glycol Ratio on Flexural Properties of Oil Palm Empty Fruit Bunch-Polyurethane Composites

Abstract

Oil palm empty fruit bunch (EFB)-polyurethane (PU) composites were produced. The effects of the isocyanate (NCO)/glycol (OH) ratio, glycol type, and mixtures (polyethylene glycol PEG 400 (M _w 400) and polypropylene glycol PPG 400 (M _w 400)) on the flexural properties were investigated. The NCO/OH ratio had a significant effect on the flexural properties of the EFB-PU composites. Composites made with PEG 200 exhibited higher flexural properties than with PEG 400 and PPG 400. The flexural properties were also found to be influenced by the PPG 400/PEG 400 ratio.     

Effect of ingredient ratios of rigid polyurethane foam on foam core panels properties

One‐step manufacturing process (in‐situ foaming) provide great potential for the production of foam core panels. Polyurethane (PU) foam showed good applicability for use for in‐situ foaming. Here, the effect of ingredient ratios of rigid PU foam on foam performance and panel properties is investigated. It was observed that the isocyanate (ISO) content and polyols (PO) type and content significantly change the foam and panel properties. Foam cell density, as the most important factor influencing the foam characteristics, was higher in foams with higher ISO and polyether content. Bending strength, internal bond and screw withdrawal resistance of the foam core panels were significantly enhanced when the ISO and polyether content was increased in the foam formulation. Varying the ISO content had no influence on panel properties with higher content of polyester (60%) in the PO blend. Varying the foam ingredient ratios did not change the thickness swelling, while the water absorption was dependent on the foam components ratios. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44722.     

环戊烷发泡剂/组合聚醚体系的研究

通过相容性、自由发泡、模具发泡和流动性实验对环戊烷发泡剂/组合聚醚体系进行了研究。探讨了聚醚多元醇、催化剂和泡沫稳定剂对聚氨酯发泡体系性能的影响。结果表明:用环戊烷发泡剂/组合聚醚体系制备的聚氨酯泡沫流动性好成,本低泡,沫性能符合冰箱及冰柜指标要求。     

环境友好型阻燃高回弹聚氨酯软泡性能

开发环境友好型聚氨酯是目前聚氨酯（polyurethane,PU）泡沫塑料领域的热点课题。在PU中引入大豆分离蛋白质（soy protein isolate,SPI）,采用阻燃聚醚制备了环境友好型阻燃高回弹聚氨酯软泡。研究了SPI的不同添加方式及用量对聚氨酯软泡物理、力学、阻燃和生物降解性能的影响。结果表明,SPI以添加的方式而不是替代聚醚的方式加入软泡性能更好;少量添加SPI可以提高PU软泡的开孔率、密度、压陷硬度、舒适因子、回弹率和断裂伸长率,对压缩永久变形率、拉伸强度和极限氧指数影响不大。SPI改变了PU的硬段结构,可以有效促进聚氨酯泡沫的生物降解。     

Investigations on the adhesion and interfacial properties of polyurethane foam/thermoplastic materials

The adhesion and interfacial properties of polyurethane (PU) foams with thermoplastic (TP) materials were investigated using different techniques. The adhesion performance of PU foam with TP materials was evaluated using the peel test method, and the adhesion durability was checked after different climate treatments. X‐ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), and contact angle measurements were used to study the surface and interface morphology of PU foam and TP material system. Three types of PU foam samples which differ in their composition and also five commercially available TP blends systems, based on poly(carbonate), poly(styrene‐co‐maleic anhydride), poly(acrylonitrile‐butadiene‐styrene), and silicone acrylate rubber have been used. The slow reacting foam shows the best adhesion properties with all the TP materials. The climate treatments strongly effected the PU foam adhesion durability with poly(carbonate) containing TP materials (70–80% loss in adhesion), but nearly no effect with poly(styrene‐co‐maleic anhydride). The samples with lowered adhesion could be separated by peeling without visible foam residues on the TP surface. AFM, XPS, and surface tension studies have shown that the surface properties of the TP material are still governed by the PU foam. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 479–488, 2007     

Hydroxyl‐decorated ammonium polyphosphate as flame retardant reinforcing agent in solvent‐free two‐component polyurethane

Despite being extensively implemented in research, it remains challenging but highly desirable to develop ammonium polyphosphate (APP)‐based polyurethane (PU) combining excellent flame retardancy and improved mechanical properties. Herein, hydroxyl‐decorated APP (OH‐APP) was successfully fabricated through a facile, green, yet efficient cation exchange reaction with N‐methylethanolamine, and utilized as a multifunctional reinforcing agent for solvent‐free two‐component PU in the curing process. Results demonstrate that the conjugation of OH‐APP imparts to the resultant cured PU samples (PU/OH‐APP) enhanced fire safety and smoke suppression performance, as evidenced by the considerable decrease in peak heat release rate, total heat release, peak smoke production rate and total smoke production by 75.4, 30.1, 64.3 and 14.4% over those of pure PU. Furthermore, the tensile strength of PU/OH‐APP is improved by 66.5%, while the ductility is well maintained, highlighting its promising potential in industrial applications. This work is aimed at opening a new avenue for the development of APP‐based PU with outstanding performances through covalent anchoring approaches. © 2017 Society of Chemical Industry     

Processing‐structure‐property relationship in rigid polyurethane foams

Rigid polyurethane (PU) foam is used as a thermal insulating and supporting material in domestic refrigerator/freezers and it is produced by reaction injection molding (RIM) process. There is a need to improve the thermal property of rigid PU foam but this is still a challenging problem. Accordingly, this work investigates the RIM process parameters to evaluate their effects on rigid PU foam's structure and hence property. It has been found that mold temperature is a key parameter whereas curing time has negligible effect on structure of PU foam. Cell size, strut thickness, and foam density have been found very critical in controlling the thermal and mechanical properties. Upper and lower values of 30 to 32 kg/m³ density are critical to observe contribution of radiation and solid conductivity separately. Finally, PU foam with 160 µm average cell size, 16 µm strut thickness, below 10% open cell content, and 30 to 32 kg/m³ density allow obtaining better thermal insulation without significant reducing in the compressive strength. The presented work provides a better understanding of processing‐structure‐property relationship to gain knowledge on producing high‐quality rigid PU foams with improved properties. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44870.     

Phosphorus‐containing silica gel‐coated ammonium polyphosphate: Preparation,characterization, and its effect on the flame retardancy of rigid polyurethane foam

A phosphorus‐containing silica gel was synthesized via a reaction between phenyl dichlorophosphate, poly(ether polyol), and γ‐aminopropyltriethoxysilane. Ammonium polyphosphate (APP) was modified by the synthesized phosphorus‐containing silica gel (MAPP) and then incorporated into the rigid polyurethane foam (PU). Results showed that APP had a smaller particle size, lower initial decomposition temperature, better heat resistance at high temperature, and better compatibility with PU matrix after the modification. The cone calorimeter test results showed that the incorporation of MAPP obviously reduced the values including peak of heat release rate, total heat release, average effective heat of combustion, and total smoke release, and increased the char yield of PU composite comparing with APP. The improved flame retardancy of PU/MAPP composite was attributed to the quenching effect of PO· and PO₂· free radicals released by MAPP in the early stage and the improved thermal stability of phosphorus‐ and silicon‐containing char layer formed in the later stage. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46334.     

无卤阻燃聚氨酯泡沫塑料的性能研究

以多元醇、二异氰酸酯、聚磷酸铵(APP)、三聚氰胺(MA)等为原料,采用一步法,制得阻燃聚氨酯泡沫塑料。研究了不同阻燃剂的用量对聚氨酯泡沫的力学性能、热性能和阻燃性能的影响。结果表明,材料拉伸强度随阻燃剂添加量的增加而增加;材料的极限氧指数和在500℃时的分解残留量均随复合阻燃剂添加量的增加先增大后减小;APP/MA复合阻燃剂的效果好于单组分APP。     

Exceptionally flame-retardant flexible polyurethane foam composites: synergistic effect of the silicone resin/graphene oxide coating

A facile strategy was developed to fabricate flexible polyurethane (PU) foam composites with exceptional flame retardancy. The approach involves the incorporation of graphene oxide (GO) into a silicone resin (SiR) solution, which is then deposited onto a PU foam surface via the dip-coating technique and cured. Fourier-transform infrared spectroscopy, scanning electron microscopy, and Raman spectroscopy measurements demonstrated that the SiR and GO were successfully coated onto the PU skeleton and the intrinsic porous structure of the PU foam remained intact. The effects of SiR and GO on the mechanical and thermal stability and flame retardancy of PU composites were evaluated through compression tests, thermogravimetric analysis, vertical combustion tests, and the limiting oxygen index. The measurement results revealed that the composites (PU@SiR-GO) showed superior flame retardancy and thermal and mechanical stability compared to pristine PU or PU coated with SiR alone. The mechanical and thermal stability and the flame-retardant properties of the PU composites were enhanced significantly with increasing GO content. Based on the composition, microstructure, and surface morphology of PU@SiR-GO composites before and after combustion tests, a possible flame-retardance mechanism is proposed. This work provides a simple and effective strategy for fabricating flame-retardant composites with improved mechanical performance.