Phenol Formaldehyde Resin Content Research Articles

Tribological investigations of hemp reinforced NAO brake friction polymer composites with varying percentage of resin loading

NAO brake friction materials with 4%, 5%, and 6% (w/v) sodium hydroxide treated hemp fiber reinforcement having 25% wt. fiber loading and fixed percentage of phenol formaldehyde resin content (20% wt.) along with other fillers have been studied and reported by the authors earlier. However, the effect of variations in the resin content on the tribological performance has been studied and reported in the present paper. Five variants were prepared with varying percentages of phenol formaldehyde resin from 12% wt. to 22% wt. with incremental steps of 2% wt, along with the optimum of 6% (w/v) sodium hydroxide treated hemp fibers and other fillers. The prepared test variants’ tribological characterization was done using Taguchi’s L25 orthogonal array on a pin-on-disc experimental setup, as per ASTM G99, at room temperature and compared with the best of the earlier studied friction composite. Fade and recovery tests of the best of the earlier studied and present ones were performed on a chase tribology tester per SAE J661 standards. The results revealed moderate coefficient of friction of 0.4496, lower wear rate of 0.57 gm, and better fade recovery for the HF25P20 variant compared to its counterparts studied here.

Effect of the Adhesive System on the Properties of Fiberboard Panels Bonded with Hydrolysis Lignin and Phenol-Formaldehyde Resin.

This study aimed to propose an alternative technological solution for manufacturing fiberboard panels using a modified hot-pressing regime and hydrolysis lignin as the main binder. The main novelty of the research is the optimized adhesive system composed of unmodified hydrolysis lignin and reduced phenol–formaldehyde (PF) resin content. The fiberboard panels were fabricated in the laboratory with a very low PF resin content, varying from 1% to 3.6%, and hydrolysis lignin addition levels varying from 7% to 10.8% (based on the dry wood fibers). A specific two-stage hot-pressing regime, including initial low pressure of 1.2 MPa and subsequent high pressure of 4 MPa, was applied. The effect of binder content and PF resin content in the adhesive system on the main properties of fiberboards (water absorption, thickness swelling, bending strength, modulus of elasticity, and internal bond strength) was investigated, and appropriate optimization was performed to define the optimal content of PF resin and hydrolysis lignin for complying with European standards. It was concluded that the proposed technology is suitable for manufacturing fiberboard panels fulfilling the strictest EN standard. Markedly, it was shown that for the production of this type of panels, the minimum total content of binders should be 10.6%, and the PF resin content should be at least 14% of the adhesive system.

High‐strength wood‐based composites via laminated delignified wood veneers with different adhesive contents for structural applications

AbstractThe processing of natural wood into a high‐performance wood‐based composite to broaden the potential applications of wood can be achieved by various techniques using bulk wood as a raw material. However, attention has seldom been paid to the use of wood veneers for preparing high‐performance structural materials. In this study, delignified birch veneers are used as raw materials to fabricate high‐strength delignified wood‐based laminated composites (DWLCs) with phenol‐formaldehyde (PF) resin as adhesive. The DWLCs with a PF resin content of 40% had high mechanical properties and displayed flexural and tensile stress of 405.8 and 324.4 MPa, respectively. The flexural and tensile stress are 1.24 and 1.21 times higher than those of natural wood‐based laminated composites (WLCs). And we confirmed that partial delignification could contribute to enhancing the mechanical properties of high‐strength wood‐based composites. By using scanning electron microscopy (SEM), and energy‐dispersive spectroscopy (EDS), the strengthening mechanisms of the high‐performance DWLCs were investigated. Due to both the surface of the cell lumen and cell walls being filled with PF resin, the wood microstructure was cured under high pressure so that the DWLCs were enhanced.

Sifat Fisis dan Mekanis Oriented Strand Board Hibrida Bambu Pada Berbagai Shelling Ratio (Physical and Mechanical Properties of Hybrid Bamboo Oriented Strand Board at Various Shelling Ratios)

Hybrid Bamboo Oriented Strand Boards (OSB) were produced to improve bamboo OSB's physical and mechanical properties. Shelling ratio adjustment of the strand type combination could determine the optimal physical and mechanical properties of hybrid bamboo oriented strand boards (OSB). The purpose of this study was to evaluate the physical and mechanical properties of hybrid betung and andong bamboos OSB at various shelling ratios. Steam modified strands of betung and andong bamboo were used as an outer layer and core layer, respectively. Hybrid bamboo OSBs were prepared with 0.7 g cm-3 target density and 8% phenol-formaldehyde resin content. Three layers of OSB were made with outer: core shelling ratios of 30:70, 40:60, 50:50, and 60:40. The physical and mechanical properties of the OSB were tested referring to the JIS A 5908-2003 standard. The targeted board density was achieved and the physical properties of all hybrid bamboo OSB have met the requirement of CSA O437.0 (Grade O-1) standard criteria. The parallel modulus of elasticity (MOE) and modulus of rupture (MOR) increased with increasing outer layer ratio. However, the perpendicular MOE and MOR decreased with increasing outer layer ratio. The internal bonding (IB) of the OSB with a shelling ratio of 30:70 and 40:60 met with the requirement of the CSA O437.0 (Grade O-1) standard.

Medium-density fibreboards bonded with phenol-formaldehyde resin and calcium lignosulfonate as an eco-friendly additive

ABSTRACT The potential of addition of calcium lignosulfonate as an eco-friendly additive with a phenol-formaldehyde (PF) resin, at different ratios, to produce medium-density fibreboards (MDF) with acceptable properties, was investigated in this work. The fibreboards were fabricated in the laboratory with low PF resin percentage (3%, 4%, 5%), while the addition levels of calcium lignosulfonate varied from 5% to 15% (on the dry fibres). The physical and mechanical properties of the fibreboards were evaluated, and further statistically analysed in order to determine the optimal values of PF resin content and lignosulfonate addition for fulfilling the European standards. It was shown that at the low PF resin content (3%), addition of lignosulfonate should not exceed 10% to avoid deterioration in the mechanical properties. It was concluded that PF resin content of 3.5% can be recommended for the production of lignosulfonate-PF bonded MDF panels to comply with the EN standard requirements.

A Study of Non-Isothermal Kinetic Reaction for Vulcanization of Chloride Butyl Rubber via Phenol Formaldehyde Resin

Abstract Brominated tert octyl phenol formaldehyde resin (PR) is an important cross linker for chlorinated butyl rubber (CIIR). There are two competitive reactions in the vulcanization process of CIIR, the cross-linking reaction and the self-poly-condensation reaction of PR. The cross-linking density was measured by the equilibrium swelling method. The results showed: with the increasing of PR content, the cross-linking density increased when it was less than 10 phr, and decreased when the PR content exceeded 10 phr. The kinetics equation of cross-linking reaction and the self-poly-condensation reaction was obtained by non-isothermal DSC method. The results showed that the concentration index n2 of PR in the cross-linking reaction was far less than the concentration index n3 of PR in the self-poly-condensation reaction. The self-poly-condensation reaction was more sensitive to the concentration of PR. This explained that the cross-linking density was out of proportion with the cross linker PR content. The mechanical properties and the dynamic mechanical properties were investigated by the universal testing machine and the dynamic mechanical performance analysis (DMA), respectively. The results showed that the cross-linking density had a great impact on the mechanical properties and the dynamic mechanical properties, and the variation trend of the cross-linking density was further confirmed by the corresponding variation of the properties. When the PR content was 5 phr, the CIIR vulcanizates had better mechanical properties.

Effect of phenol formaldehyde resin as vulcanizing agent on flow behavior of HDPE/PB blend

Thermoplastic elastomer (TPE) based on High density polyethylene (HDPE)/polybutadiene (HDPE/PB=70/30 parts) blends containing 1, 3, 5, 7 and 10wt.% of dimethylol phenolic resin as a vulcanizing agent in the presence of SnCl2 as catalyst was prepared. The dimethylol phenolic resin was prepared in our laboratory. The blends were compounded in mixer-60 attached to a Haake rheochord meter-90. The rheological properties were measured at temperatures 140, 160, 180 and 200°C. The linearity of the flow curve appeared for 5% of the vulcanizing agent. The shear stress and shear viscosity have increased upon increasing the shear rate over a range of loading levels of vulcanizing agent of 1%, 3%, 5%, 7% and 10%. This may be attributed to the increased vulcanization between polyethylene and the rubber blend. The flow behavior index of the system shows a pseudo plastic nature behavior (since n<1). The consistency index (K) increased with the increase in the phenol formaldehyde resin content and the temperature. Hence, the increase in the value of the consistency index (K) of the polymer melts refers to more viscous materials prepared. The activation energy for the TPE blends fluctuated indicating that there is phase separation; where each polymer behaved separately. This study showed that HDPE/PB blends are characterized with good rheological properties, which can be recommended to be processed with the injection molding technique.

Effect of Fiber Surface Treatment Techniques on Properties of Short Carbon Fiber Reinforced Phenol Formaldehyde Resin/Graphite Composite Bipolar Plate

Research was done on carbon fiber surface treatment techniques on boundary-bonding state and properties of short carbon fiber reinforced phenol formaldehyde (PF) resin/graphite composite. By gas-phase oxidative surface treatment (GPOST)、gas-phase and liquid-phase oxidative surface treatment (GLPOST), carbon fiber and PF resin /graphite matrix is on weak boundary bonding state. The exerted outside stress can not be effectively transmitted, the composite strength is lower than that of PF resin/graphite matrix; By thick nitric acid liquid-phase oxidative surface treatment (TNALPOST) which the nitric acid has high density, fiber and matrix is on relatively weak boundary bonding state, the exerted outside stress can be effectively transmitted and composite strength can be raised on some degree. With carbon fiber content by TNALPOST 3.wt%~ 4.wt% and PF resin content 15.wt%, the composite can meet both the mechanical strength and electrical conductivity requirement on carbon filler/polymer bipolar plate by USA Department of Energy.

Properties of Graphite Matrix Composite Bipolar Plate Reinforced by Short Carbon Fiber

Short carbon fiber is used to reinforce phenol formaldehyde (PF) resin/graphite composite. With carbon fiber by thick nitric acid liquid-phase oxidative surface treatment (TNALPOST) and its content 3.wt%~ 4.wt%, the composite flexural strength is increased highly and electrical conductivity is also increased on some degree. To PF resin/graphite matrix material without carbon fiber added, if PF resin content is 15.wt%, its flexural strength is 49.0MPa and electrical conductivity is 111S/cm. But with adding carbon fiber by TNALPOST and the same PF resin content , the composite flexural strength and electrical conductivity approach 68MPa、122S/cm respectively, both mechanical property and electrical property satisfy the requirement of USA Department of Energy on carbon filler/polymer composite bipolar plate. The PF resin/graphite composite without carbon fiber added presents brittle fracture mode, but with carbon fiber added, it presents ductile fracture mode. According to the fracture morphology by scanning electron microscopy, carbon fiber and matrix is on relatively weak boundary bonding state accompanied by fiber de-bounding、sliding、pulling-out and bridge-making to crack, they are main factors contributed to improving composite toughness.

Study on the Composites of Phenol Formaldehyde Resin/Graphite Reinforced by Milled Carbon Fibers for Bipolar Plates

Composites of phenol formaldehyde (PF) resin/graphite reinforced by milled carbon fibers (MCFs) for bipolar plates are obtained by hot compression molding. The raw materials of the MCF particles, PF resin powder and graphite powder are simply dry powder ball milled and mixed. The effects of PF resin content and the content, granularity and surface treatment methods, such as air oxidation and Fenton/ultraviolet (UV) liquid-phase oxidation of MCFs on the electrical conductivity and flexural strength of the composites are measured by methods of four-point probe technique and three point flexural test, and the fracture patterns of the composites are analyzed by scanning electron microscope (SEM). The results indicate that the electrical conductivity decreases and flexural strength increases with the increase of PF resin content. Especially, the values of electrical conductivity and flexural strength can reach 165.28 S.cm-1 and 55.11MPa respectively when the PF resin content was 17% in weight. The properties of composites reinforced by air oxidation treated MCFs are better than those by liquid-phase oxidation treated one. The electrical conductivity and flexural strength of the composites are 208.12S.cm-1 and 57.44 MPa when they reinforced by 5% MCFs which treated by air oxidation at 450 . Compared with the nonreinfoced composites, the properties of reinforced composites increase 25.92% in electrical conductivity and 4.23% in flexural strength.

Manufacture of laminated strand veneer (LSV) composite. Part 1: Optimization and characterization of thin strand veneers

Abstract The forest resources are changing due to fire prevention and depletion of old growth forest. Applications for small-diameter juvenile timber, especially for low-value species, such as ponderosa pine (Pinus ponderosa) are needed. In this study, a novel thin wood strand composite of P. ponderosa, 3.2 mm thick, is introduced as a veneer substitute. Optimization was performed for the processing parameters phenol formaldehyde resin content, platen temperature, and the aspect ratio strand length to thickness (L/t). Mean modulus of elasticity and modulus of rupture values of 10.2 GPa and 79.1 MPa, respectively, were obtained with the optimized formulation (5.5% resin, platen temperature 152°C, and aspect ratio of 430). These values were approximately 2–2.5 times higher than the parent small-diameter ponderosa pine lumber. The results indicate that fast-growing low-density species – such as hybrid poplars, or small-diameter timber with predominantly juvenile wood – could potentially be used to manufacture strand veneers of consistent quality with significantly higher strength and stiffness than parent material.

Potential of visible and near infrared spectroscopy to quantify phenol formaldehyde resin content in oriented strandboard

In this note, a preliminary test of the ability of visible and near infrared spectroscopy (NIR) coupled with multivariate statistical methods is described to predict the phenol-formaldehyde (PF) adhesive content in oriented strandboard (OSB) post manufacture. A visible-NIR-based PLS model could predict moderately well (RMSEP0=.60%) the PF loading in the face layers of pine OSB after pressing. The spectral absorbance at 614 nm was significantly different between PF loadings. NIR may provide the basis for an on-line, real-time quality control tool providing feedback information to the press.

Gel acrylonitrile–butadiene elastomer toughened polyoxymethylene blends

The polymer blends of polyoxymethylene (POM) and gel acrylonitrile–butadiene elastomer (GNBE) with phenol formaldehyde resin (PFR) as the compatibiliser were prepared, and the structure and properties were studied. The results show that GNBE is an excellent toughening agent for POM. The blend POM/GNBE (80/20) with 6 phr PFR attains a notched Charpy impact strength of 21·6 kJ m−2, an elongation at break of 133% and a tensile strength of 33·8 MPa. PFR is incorporated into GNBE and the hydroxyl groups in PFR form intermolecular hydrogen bonds with POM. Dynamic mechanical analysis studies show that POM and GNBE are partially miscible and the miscibility of the blends is improved by PFR. The results from TEM show that the size of the dispersed phase of the ternary blends decreased with increasing PFR content in the blends. A rubber band of GNBE dispersed phase and a complex wrapped structure in POM were observed in the POM/GNBE and POM/GNBE/PFR blends.

Sugar beet cellulose nanofibril-reinforced composites

Cellulose was isolated from sugar beet chips, a by-product of sugar production, by wet chemistry. Further processing of the cellulose with a high-pressure homogeniser led to the disruption of cell walls into nanofibrils. Cellulose sheets obtained by casting and slow evaporation of water showed higher strength and stiffness when homogenised cellulose was used compared to unhomogenised cellulose. These cellulose sheets showed significantly better mechanical performance than Kraft paper tested for reference. The addition of cellulose nanofibrils to a polyvinyl alcohol and a phenol-formaldehyde matrix, respectively, demonstrated excellent reinforcement properties. The best mechanical performance was achieved for a composite with a phenol-formaldehyde resin content of 10%, which showed a tensile strength of 127 MPa, a modulus of elasticity of 9.5 GPa, and an elongation at break of 2.9%.

Produção de chapas de partículas orientadas “OSB” de &lt;i&gt;Eucalyptus grandis&lt;/i&gt; com diferentes teores de resina, parafina e composição em camadas.

Este trabalho foi desenvolvido com o objetivo de avaliar a influência dos seguintes parâmetros de processo de produção sobre as propriedades das chapas "OSB": composição das chapas em camadas cruzadas com proporções face-miolo-face de 30-40-30 e 20-60-20 em relação à composição homogênea; e, quantidades de 3, 4,5 e 6,0% de resina fenol-formaldeído, com incorporação de 0,5 e 1,0% de emulsão de parafina. Os resultados demonstraram que a composição das chapas, com a relação 20-60-20, apresentou melhor balanço das propriedades de flexão estática entre os sentidos de ensaios paralelo e perpendicular ao plano da chapa. A quantidade de 6,0% de resina foi a que resultou em melhores propriedades físico-mecânicas das chapas "OSB". A produção de chapas "OSB" de Eucalyptus grandis, com 4,5 e 6,0% de resina fenol-formaldeído, superou as exigências mínimas de propriedades mecânicas das chapas "OSB" referendadas pela norma canadense CSA 0437-0 (1993).

Compressive deformation of wood impregnated with low molecular weight phenol formaldehyde (PF) resin II: effects of processing parameters

To obtain high-strength phenol formaldehyde (PF) resin-impregnated compressed wood at low pressing pressure, the effects of resin content, preheating temperature, pressing temperature, and pressing speed on the compressive deformation of oven-dried low molecular weight PF resin-impregnated wood was investigated. With an increase of PF resin content, the Young’s modulus of the cell wall perpendicular to the fiber direction decreases, and collapse-initiating pressure decreases linearly with the Young’s modulus. This indicates that the occurrence of cell wall collapse is strain-dependent. By increasing preheating temperatures, the collapse-initiating pressure increases due to the increment of the Young’s modulus of the cell wall. An increase in pressing temperature results in the thermal softening of the cell wall and causes collapse at a lower pressure. The wood is compressed effectively despite accelerated resin curing. The pressing speed significantly affects the viscoelastic deformation of the cell wall and the wood is well deformed with decreasing pressing speed, although the differences in density and mechanical properties are relatively small after a pressure-holding period of 30 min. In all the parameters examined in this study, the Young’s modulus and bending strength increase with increasing density.

Application of cure-accelerated phenol-formaldehyde (PF) adhesives for three-layer medium density fiberboard (MDF) manufacture

This study was conducted to optimize hot pressing time and adhesive content for the manufacture of three-layer medium density fiberboard (MDF) through the cure acceleration of phenol-formaldehyde (PF) adhesives by adding three carbonates (propylene carbonate, sodium carbonate, and potassium carbonate) in the core layer. Carbonate type, carbonate level, PF resin content, and hot pressing time were evaluated on the basis of the performance of MDF panels prepared. The application of cure-accelerated PF adhesives by the addition of propylene carbonate reduced both PF resin content and total hot pressing time by 38% and 29%, respectively, for the manufacture of quality three-layer MDF panels (19.1 mm thickness) under the hot-pressing temperature of 205 °C. The optimum concentration of propylene carbonate for cure acceleration of PF resin was found to be 3 wt% by weight based on the resin solids. Bending properties, on one hand, were independent of carbonate type and level, and complied with the minimum requirements by ANSI. Internal bond (IB) strength, on the other hand, was closely related with carbonate types and level used.

炭素複合材料の耐火性能と電磁波遮へい性能

Graphite and phenol-formaldehyde resin spheres (GPS) were used in the manufacture of fire resistive and electromagnetic shield composites. The effects of specific gravity, thickness and phenol-for-maldehyde resin content of GPS on the fire resistivity and electromagnetic shield of composites were discussed. The carbonizing temperature of the composites relative to the fire resistive and electromagnetic shielding properties was also discussed. The fire resistivity was tested by a burn-through method, by cutting with an oxygen-acetylene torch and by an oxygen index method in accordance with the Japanese Industrial Standards (JIS) K 7201. The electromagnetic shielding property was tested by a DUAL chamber method in accordance with ASTM ES7-83. The fire resistive and electromagnetic shielding properties of the composites were improved by increasing the specific gravity and thickness of the GPS composites as well as increasing the carbonizing temperature, and reducing the phenol-formaldehyde resin content.