Methylenedi Phenyl Isocyanate Research Articles

Development of Electrically Conductive Wood-Based Panels for Sensor Applications.

This study investigates the development of electrically conductive panels for application as emergency detection sensors in smart house systems. These panels, composed of wood chips coated with polymeric methylene diphenyl isocyanate, were modified with carbon black and carbon fibers to enable detection of moisture, temperature, and pressure variations. Manufactured via hot pressing, the panels retained standard mechanical properties and exhibited stable performance under diverse environmental conditions. Carbon black-filled panels achieved electrical percolation at a lower filler concentration (5%) compared to carbon fiber-filled panels. The incorporation of carbon black reduced the electrical resistivity to 8.6 ohm·cm, while the addition of carbon fibers further decreased it to 7.7 ohm·cm. In terms of sensor capabilities, panels containing carbon fibers demonstrated superior sensitivity to moisture and pressure changes. However, carbon black was ineffective for temperature sensing. Among the carbon fiber-filled panels, those with 20 wt.% concentration exhibited the best performance for moisture and pressure detection, whereas panels with 40 wt.% carbon fiber content displayed the most reliable and consistent temperature-sensing properties.

Kraft lignin-based polyurethanes: Bulk properties, stability and adhesion to native aluminum surfaces

Lignin as a byproduct from pulp and paper manufacturing has been extensively investigated as raw material for polymer developments. Although, fundamental topics related to the adhesion mechanisms of lignin-based reactive polyurethanes (LPU) still remain unclear. In this work, LPU thin films on native aluminum surface were prepared and characterized. Diluted in THF, employed as the solvent, reactive mixtures of 4,4′-methylene diphenyl isocyanate (4,4′-MDI) and the soluble fraction of three lignins (liquid hydroxypropylated Kraft lignin and two powder Kraft lignins with different pH) were used for LPU thin film deposition via spin coating on aluminum (PVD layer on silicon wafer). The resulting film thickness ranged from 8 nm to several micrometers. The chemical state of the three LPU compositions was assessed in bulk by infrared attenuated total reflectance (IR-ATR) and in the thin films by infrared external reflection absorption spectroscopy (IR-ERAS). Binding energies of 4,4′-methylene diphenyl diisocyanate with aliphatic and aromatic hydroxyl groups were estimated using Density Functional Theory (DFT) simulations. Thus, besides the elucidation of the bulk chemical state of LPUs, the relation to adhesion and stability of LPUs to a native aluminum surface was evaluated. In addition, film topography and homogeneity were monitored by SFM. All lignin types form uniform and homogeneous films. Results revealed a higher consumption of isocyanate groups (NCO) in the formulation with the alkaline Kraft lignin than with the acid one, despite its lower hydroxyl content. A gradient of unreacted NCO was observed in LPU thin films obtained with the powder Kraft lignin types. Residual NCO is also found in thicker films, while the thinnest films did not contain unreacted NCO anymore, indicating the activating effect of the native aluminum surface on LPU formation.

Properties of sandwich boards with a core made of bio-composite particleboard containing wood particles and walnut shells

The aim of the research was to investigate the possibility of producing bio-composite particleboard with a density reduced to 500–550 kg/m3, containing 25% and 50% of walnut shells. In addition, the study also concerned the possibility of using these materials in sandwich systems. Based on the results, it was found that partial replacement of wood particles with ground shells leads to a significant reduction in the strength of the boards bonded with urea-formaldehyde (UF) resin. However, the implementation of a hybrid gluing method consisting of gluing wood particles with UF resin and walnut shells with 4,4′-methylenediphenyl isocyanate (pMDI) caused a significant improvement in the strength of the boards, especially for the variant with the highest shells content. Despite that, the manufactured materials still do not meet the requirements for furniture boards. The next step of the research has shown that these boards can perform well as a core layer in the sandwich boards covered with high-strength HDF boards. Moreover, it was found that increasing the share of walnut shells positively affected the dimensional stability of the resultant boards (thickness swelling and water absorption). However, substitution of wood with shells accelerated the ignition and flameout times of the boards. It increased the heat release without significantly affecting the percentage loss of the boards’ mass during exposure to fire.

Highly efficient reactive compatibilization of biodegradable PBAT/EVOH blend by pMDI

AbstractPolymeric methylene diphenyl isocyanate (pMDI) was used as a reactive compatibilizer to improve the mechanical properties of the PBAT/EVOH blend. Initially, pMDI was blended with pure polymers. Adding pMDI led to a 10‐fold rise in the viscosity of PBAT/pMDI compared to pure PBAT, with an enhancement in tensile properties, attributed to pMDI's chain‐extending effect in the PBAT phase. Conversely, a reduction in the elongation at the break of EVOH/pMDI indicated a cross‐linking role for pMDI in the EVOH phase. Notably, the blend with 1 wt% of pMDI showed a high tensile strength of 38 MPa by route II, much above 13.5 MPa for the one prepared by route I, and 14 MPa for the blank PBAT/EVOH blend without pMDI. Fourier transform infrared (FTIR) spectra, FE‐SEM images, and dynamic mechanical thermal analysis (DMTA) results confirmed the occurrence of effective reactions in route II. Modification of the blend with pMDI decreased the crystallinity of EVOH, the size of EVOH droplets, and the oxygen transmission rate (OTR) of the blends. However, an increase in the pMDI content above 0.5 wt% decreased OTR. Therefore, the modified blends of PBAT/EVOH with pMDI can be used as an efficient compatibilizer or adhesive layer in PBAT/EVOH blends or multilayer films for agricultural or food packaging applications.

Investigating relative density effects on quasi-static response of high-density Rigid Polyurethane Foam (RPUF)

This study aims at characterisation of various densities of Rigid Polyurethane Foam (RPUF) under quasi-static tension and compression. The density of foam is key parameter in selection of suitability for structural applications. Various densities of RPUF are synthesised using commercial grade Polyols and Methylene diphenyl isocyanate (MDI). The ratio of mixing both constituents was maintained at 1:1.15 for polyol and MDI respectively. Free rise density of the foam was achieved at 234 kg/m3 and is considered the baseline density for comparison. The higher than baseline densities were achieved by blowing the mixture into a mould with variable pouring times and three densities in the range of 252 kg/m3, 303 kg/m3 and 353 kg/m3 were achieved. The tensile and compression specimens were prepared from the manufactured blocks. SEM images were taken from the blocks of various densities and uniform cell patterns were observed for all densities. The specimens were then tested under compressive and tensile loads. It was found that the specimen exhibit consistency in results and the density affects the mechanical properties directly. Optimum density of foam for energy absorption capability of RPUF based on specific work done is also estimated. A phenomenological model based on relative density of foam was developed to assess material behaviour which can reduce the requirement of test specimens for obtaining a set of particular material properties.

Environment-friendly stimulus-sensitive polyurethanes based on cationic aminoglycosides for the controlled release of phytohormones

PurposeControlled release systems are an efficient alternative for the effective use of agricultural supplies. Among the most versatile controlled release systems are intelligent or stimulus-sensitive polymeric materials, since these materials are multipurpose and adaptable alternatives that offer great adaptability for agricultural applications. The objective of this work was to develop stimulus-sensitive polyurethanes (PUs) based on cationic aminoglycosides (CAG) to be used as an active phase for the manufacture of systems for the controlled release of phytohormones such as naphthalene acetic acid (NAA).Design/methodology/approachThe synthesis of stimulus-sensitive PUs was carried out by a polycondensation reaction using CAGs and methylene diphenyl isocyanate (MDI) as precursors. The NAA retention and release experiments were performed at different pH values and ionic forces to include the acidity and salinity of agricultural soils.FindingsThe results demonstrate that PUs can be obtained from CAG and MDI using the one-step method. The retention of NAA increased as the CAG content increased in the polymer structure, while it is seen that the effect of pH is weak compared to the effect of ionic strength. On the other hand, the release of NAA from cationic PUs can be accomplished by small changes in ionic strength that are mainly affected by the composition of the PU and the pH. The results suggest that, for developed systems, retention and release of NAA is affected by other interaction mechanisms that could probably be related to p-aromatic interactions.Research limitations/implicationsFindings are limited to controlled conditions and the expanding of results to extensive crops should be analyzed in next research studies.Practical implicationsThe practical implications of this study are improving of control for the dosage of phytohormones in stake propagation crops, greenhouse crops, optimization of reseeding operations, among others.Social implicationsThe social implication of this study is reduction of pollution by addition of excess of NAA, in consequence, production costs are decreased.Originality/valueOriginality and value of this research is the use of PUs based on CAG, and in consequence, the possibility to build novel environment-friendly systems for phytohormone dosage.

Greener Nanocomposite Polyurethane Foam Based on Sustainable Polyol and Natural Fillers: Investigation of Chemico-Physical and Mechanical Properties.

Nowadays, the chemical industry is looking for sustainable chemicals to synthesize nanocomposite bio-based polyurethane foams, PUs, with the aim to replace the conventional petrochemical precursors. Some possibilities to increase the environmental sustainability in the synthesis of nanocomposite PUs include the use of chemicals and additives derived from renewable sources (such as vegetable oils or biomass wastes), which comprise increasingly wider base raw materials. Generally, sustainable PUs exhibit chemico-physical, mechanical and functional properties, which are not comparable with those of PUs produced from petrochemical precursors. In order to enhance the performances, as well as the bio-based aspect, the addition in the polyurethane formulation of renewable or natural fillers can be considered. Among these, walnut shells and cellulose are very popular wood-based waste, and due to their chemical composition, carbohydrate, protein and/or fatty acid, can be used as reactive fillers in the synthesis of Pus. Diatomite, as a natural inorganic nanoporous filler, can also be evaluated to improve mechanical and thermal insulation properties of rigid PUs. In this respect, sustainable nanocomposite rigid PU foams are synthesized by using a cardanol-based Mannich polyol, MDI (Methylene diphenyl isocyanate) as an isocyanate source, catalysts and surfactant to regulate the polymerization and blowing reactions, H2O as a sustainable blowing agent and a suitable amount (5 wt%) of ultramilled walnut shell, cellulose and diatomite as filler. The effect of these fillers on the chemico-physical, morphological, mechanical and functional performances on PU foams has been analyzed.

Characterization of Polyurethanes from MDI, PEG 400 and Kepok Banana Hump additives with TGA, DTG and LCMS spectrometers

Polyurethanes from methylene diphenyl isocyanate (MDI), polyethylene glycol (PEG) 400 and banana weevil starch have been synthesized. This polymer has been characterized using thermogravimetric analysis (TGA), differential thermogravimetry (DTG), liquid chromatography-mass spectrometry (LCMS), and polyurethane physical tests which include: tensile and strain tests. Thermal properties can be measured using TGA and DTG devices, which aim to determine the weight of the sample under controlled conditions and cooling at a controlled rate as a function of time. TGA and DTG analysis results showed that KBH starch with a concentration of 15% in phase 1 polymerization reaction occurred at a temperature of 78 ° C, then in phase 2 a mass change of 2.87% occurred and in phase 3 saturation occurred marked by a mass loss of 97.03%. Polyurethane physical test results showed a strain of 34.37% GL and an extension of 8.6733 nm. These results indicate that polyurethane has the potential to be applied as an ingredient in the manufacture of medical devices, that operate under heating conditions

Synthesis and physical properties of poly(urethane)s using vicinal diols derived from acrylate and styrene monomers

ABSTRACTWe describe the utilization of four kinds of diol derivatives, representing structural similarity to the well‐known and commercially available vinyl monomers such as acrylate, acrylamide, styrene, and N‐substituted maleimide. The vinyl monomers are readily converted by dihydroxylation reaction to afford the vicinal diol. The synthesis of poly(urethane)s was performed by the reaction of the vicinal diol with two model diisocyanates, including methylene diphenyl isocyanate (MDI) and hexamethylene diisocyanate (HDI) in the presence of dibutyltin dilaurate to form a series of poly(urethane)s, and the effect of vicinal diol containing a side chain inherited from vinyl monomers on their thermal and mechanical properties was investigated using thermogravimetric analysis, differential scanning calorimetry, and tensile test. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 799–805

Castor Oil-Based Polyurethane Resin for Low-Density Composites with Bamboo Charcoal.

Polyurethane (PU) foam adhesives were prepared from castor oil as a polyol with isocyanate poly(4,4’-methylene diphenyl isocyanate) (PMDI) using a solvent-free process. The NCO/OH molar ratio used for the preparation of PU foams was 1.5. Water, organosiloxane and dibutyltin dilaurate were used as the blowing agent, surfactant and catalyst, respectively. The ratio of blowing agent and catalyst were adjusted to optimize the properties. The results show that PU foam prepared with 4 wt % of castor oil catalyst and blowing agent has minimal water absorption and maximal volume expansion in the PU foams. FT-IR analysis shows that a urethane bond was formed by the hydroxyl group of castor oil and the –NCO group of isocyanate PMDI. More blowing agent and catalyst could improve the volume expansion ratio and reduce water retention of PU foams. It was found that Moso bamboo charcoal (Phyllostachys pubescens) and China fir wood particle (Cunninghamia lanceolate) composites with setting densities of 500 and 600 kg/m3 can be prepared from optimized castor oil-based PU foam adhesive at 100 °C for 5 min under a pressure of 1.5 MPa. Increasing the amount of bamboo charcoal decreases the equilibrium moisture content, water absorption and internal bonding strength of the composite. Notably, bamboo charcoal composite exhibits excellent dimensional stability. The optimized density and bamboo charcoal percentages of the composite were 500 kg/m3 and 50–100%, respectively. The castor oil-based PU composites containing bamboo charcoal fulfilled the CNS 2215 standards for particleboard. This dimensionally stable, low-density bamboo charcoal composite has high potential to replace current indoor building materials.

Determination of Isocyanates in Workplace Atmosphere by HPLC

Determination of diisocyanates in the laboratories of the Authorities of Public Health was described and verified. Air samples collected in the breathing zone of workers exposed to diisocyanates were analyzed in an automotive industry. Diisocyanates (2,4-toluene diisocyanate, 2,6-toluene diisocyanate, 4,4�-methylenediphenyl isocyanate, and 1,6-hexamethylene diisocyanate) were measured by HPLC and the validation characteristics were determined. Diisocyanate exposure was monitored in the workplace atmosphere of 25 workers. Air samples from the breathing zone were collected and analyzed by HPLC after extraction. The results were compared to the occupational exposure limit. Reliability of the method was confirmed by validation characteristics for the diisocyanates. The repeatability of the method ranged from 2.98 to 4.51%, the calculated relative standard uncertainty was 11 � 12% for the parameters, and the recovery was between 99 and 103%. The low LOD and LOQ ensured the determination of the diisocyanates in the harmful concentration. Monitoring of diisocyanate exposure was performed on four different workplaces. The results showed that 2,4-toluene diisocyanate and 2,6-toluene diisocyanate were present in the concentration range from 6.3 to 13.2 �g m-3. The 1,6-hexamethylene diisocyanate was found in all cases below the limit of detection and the 4,4�-methylenediphenyl isocyanate was found only at two workplaces (between 8.3 and 44.8 �g m-3). The HPLC method was found to be appropriate for the determination of diisocyanates. Applying the method for the determination of diisocyanate exposure in four different workplaces, which produce car accessories, showed that the diisocyanate level did not exceed the occupational exposure limit set for average exposure.

Kraft scrap paper pulp as a substitute of wood chips in manufacture of particleboards resinated with hybrid pf/pmdi resin

This study analyzed feasibility of manufacture of composite particleboards resinated with a mixture of phenol–formaldehyde resin and 4,4′-methylenediphenyl isocyanate in the weight ratio 70:30. For this purpose 3-layer particleboards were produced with varying shares of Kraft scrap paper pulp in the core. Experimental boards were manufactured applying 0, 10, 15, 25, 50 and 75% substitution of wood chips with Kraft paper pulp. Analyses were conducted to determine physico-mechanical properties of boards, i.e. bending strength, modulus of elasticity, internal bond before and after the boiling test and swelling in thickness after 24 soaking in water. Based on recorded testing results it was stated that moisture resistant composite boards manufactured with a 25% substitution of wood chips with Kraft paper pulp meet the requirements of the EN 312 standard for boards used in humid conditions in terms of their strength and moisture resistance specified in the internal bond after the boiling test.

Utilization of sweet sorghum bagasse and citric acid for manufacturing of particleboard II: influences of pressing temperature and time on particleboard properties

Development of environmentally friendly particleboard made from sweet sorghum bagasse and citric acid has recently attracted attention. In this study, we investigated the effects of pressing temperature and time on physical properties, such as dry bending (DB), internal bond strength (IB), and thickness swelling (TS) of particleboard. Wet bending (WB), screw-holding power (SH), biological durability, and formaldehyde emission of particleboard manufactured under effective pressing temperature and time were also evaluated. Particleboards bonded with phenol formaldehyde (PF) resin and polymeric 4,4′-methylenediphenyl isocyanate (pMDI) were manufactured as references. Effective pressing temperature and time were 200 °C and 10 min, respectively. It was clarified that DB, IB, and TS satisfied the type 18 requirements of the JIS A 5908 (2003), and were comparable to those of particleboard bonded with PF and pMDI. The WB and SH of particleboard did not satisfy type 18 of JIS. Particleboard manufactured under effective pressing conditions had good biological durability and low formaldehyde emission. Based on the results of infrared spectra measurement, the degree of ester linkages increased with increased pressing temperature and time.

Light medium-density fibreboards (MDFs): does acetylation improve the physico-mechanical properties?

Light medium-density fibreboards (MDFs) with a target density of 580 kg m3 were produced from fibres, which were obtained by defibrillation of chips of commercially available acetylated solid wood (“Accoya®”). The fibres were produced by thermo-mechanical pulping under industry-oriented conditions in a laboratory refiner. Infrared spectra showed that after the refiner process and board production, the material exhibited the same acetyl content as the initially acetylated solid wood. The fibres were bonded with 4 and 8% (related to the dry fibre mass) polymeric methylene diphenyl isocyanate and the properties of the obtained MDFs were compared with comparable MDFs from untreated Scots pine fibres which were produced under the same conditions. The modulus of rupture tended to be slightly lower for the acetylated boards, while the modulus of elasticity and the internal bond strength (IB) were equal for the respective resin loads. Acetylation clearly reduced the thickness swelling and the water uptake during immersion in cold and boiled water compared to the unmodified boards. IB after the boil test increased with acetylation and with the resin content. The study indicates that acetylated MDFs can be produced with maintained mechanical properties but strongly enhanced moisture-related properties by defibrillation of acetylated solid wood chips in a refiner and subsequent conventional board production.

Development and material properties of reinforced plywood using carbon fiber and waste rubber powder

This article reports on the use of carbon fiber (CF) and waste rubber (WR) as reinforcing agents for plywood. The aim of this study was to determine the effects of three variable parameters: CF content, WR content, and CF length, on the mechanical and physical properties of the plywood. The properties evaluated were mechanical properties in terms of modulus of rupture (MOR), modulus of elasticity (MOE), and impact strength (IS), and physical properties including water absorption (WA) and thickness swelling (TS). Beech (Fagus orientalis) veneers having 1.8‐mm thickness were used in the production of 7‐ply plywoods. The CF and WR layers were used in the middle (core) layer of plywood samples. Bonding of the wood layers was done using urea‐formaldehyde resin (160 g/m2), and to form the CF and WR layers and bond them to wood veneers, methylene diphenyl isocyanate resin (150 g/m2) were used. Based on the results, the CF was found to have significant effect on the mechanical properties at 99% confidence level. In addition, both the mechanical and physical performances of plywoods improved with increase in the CF content and length. At a certain amount of the CF, the panels with longer (18 cm) CF showed superior mechanical properties. As it expected, the MOR values considerably reduced with the addition of WR, while the MOE, IS, WA, and TS of the specimens improved when compared with the control. The IS of the samples increased as much as 32.5% with the addition of 30 wt% of the WR. POLYM. COMPOS., 39:675–680, 2018. © 2016 Society of Plastics Engineers

Utilization of sweet sorghum bagasse and citric acid for manufacturing of particleboard I: Effects of pre-drying treatment and citric acid content on the board properties

Recently, the investigation of wood-based composites produced using agricultural waste and natural adhesives has become very important due to the decreased wood resources and fossil resource reserves. In this study, sweet sorghum bagasse and citric acid were used as the raw material and natural adhesive, respectively, for the experimental manufacture of particleboards. A pre-drying treatment of sprayed particles was performed to observe the effect of the pre-pressing moisture content of sprayed particles on the physical properties of the particleboards. In addition, the effect of the citric acid content on the physical properties of the particleboards was investigated. The boards were manufactured under the pressing conditions of 200°C for 10min. The citric acid content was varied in the range of 0–30wt%. The board size and target density were 300×300×9mm and 0.8g/cm3, respectively. Particleboards manufactured using phenol formaldehyde (PF) resin and polymeric 4,4′-methylenediphenyl isocyanate (pMDI) were used as references. The physical properties of boards prepared using pre-dried particles were superior to those of the boards prepared using non-dried particles. The physical properties of boards improved with increasing citric acid content up to 20wt%. The physical properties of boards bonded with 20wt% citric acid satisfied the requirement of the JIS A 5908 (2003) 18 type. In addition, the properties of these boards were comparable to those of boards bonded using PF resin and pMDI. Infrared (IR) spectral analysis suggested the presence of ester linkages, indicating that the carboxyl groups of citric acid had reacted with the hydroxyl groups of the sorghum bagasse to give the boards good physical properties. Consequently, it was concluded that pre-drying treatment of the particles and a citric acid content of 20wt% were effective in manufacturing particleboards composed of sweet sorghum bagasse and citric acid.

Effect of Rice Straw Steaming Time and Mixing Ratio between Acacia mangium Willd Wood and Steamed Rice Straw on the Properties of the Mixed Particleboard

Abstract This study examined the effects of rice straw steaming time and mixing ratio between rice straw and wood particle on the properties of mixed particle board from Acacia mangium Willd wood and rice straw. Rice straw and Acacia mangium Willd wood were collected in Hanoi, Vietnam. The particle board was three-layer particle board with the structural ratio of 1：3：1. The thickness, density and board size of the particle board were 18 mm, 0.7 g/cm 3 , and 800x800x18 (mm, including trimming), respectively. A resin mixture between commercial Urea-formaldehyde (U-F) adhesive and methylene diphenyl isocyanate (MDI) adhesive was used with a dosage of 12% for the core layer and 14% for the surface layer. In this experimental design, the steaming time for rice straw was 15, 30, 45, 60, and 75 minutes at 100 o C. The rice straw-wood mixing ratio was 10, 20, 30, 40, and 50%. The results showed that both mixing ratio and steaming time affect the properties of the particleboard, but the mixing ratio has a stronger impact. A higher mixing ratio and a longer steaming time resulted in a better quality of particleboard. The optimal steaming time for rice straw was 46.12 minutes with the straw-wood mixing ratio of 29.85% with the following characteristics of the particle board: the modulus of rupture (MOR) of 14.64 MPa, internal bond strength (IB) of 0.382 MPa, thickness swelling (TS) of 8.83%, and board density of 0.7-0.73 g/cm

Novel dendritic-poly(urethane-urea) hybrid thin films from hydrogen bond rich dendrons

Hydrogen bond rich segmented poly(urethane-urea) was synthesized from methylene diphenylisocyanate (MDI) and three generations of polyurea-malonamide dendrons as hard segment and polycaprolactone diol as soft segment for thin film applications. The prepared polymers were characterized using spectroscopic, microscopic and thermal analyses. The formation of urethane linkage during the prepolymer reaction and the urea linkage between prepolymer and the dendrons is confirmed by Fourier transform infrared (FTIR) spectroscopy and 1H nuclear magnetic resonance (NMR) spectroscopy. FTIR shows the presence of hydrogen bonding of –NH groups with both urethane carbonyl group from hard segment and the ether group from the soft segment. However, the phase mixing of hard and soft segments decreases with the higher generation dendrons, as evidenced from FTIR. This observation was confirmed by phase images of the atomic force microscopy (AFM). The coating when applied to clean steel substrates via dip coating reveals uniform, dense and essentially defect free morphology. The work demonstrates that the mechanical properties of the hybrid thin films are dependent on the generation of the dendrons and provides a platform for surface engineering with tunable elastic modulus.

Heat release of polyurethanes containing potential flame retardants based on boron and phosphorus chemistries

Using a polyurethane of methylene diphenyl isocyanate and 1,3-propane diol, several new non-halogenated aromatic boron and phosphorus flame retardants were evaluated for heat release reduction potential using the pyrolysis combustion flow calorimeter (PCFC). The polyurethanes were prepared in the presence of the potential flame retardants via solvent mixing and copolymerization methods, and were then analyzed via spectroscopic methods to determine if the flame retardant was still present in the final product. PCFC testing on the resulting products showed that the flame retardant molecule can have different effects on heat release depending upon how it is mixed into the polyurethane. Some materials showed strong effects on heat release reduction when reacted into the polyurethane during copolymerization, while others were more effective at heat release reduction when simply solvent blending into the polyurethane. The results from this screening study show that flame retardant chemical structure and its environment in the polymer (covalently bonded vs. noncovalent interactions) greatly affects flammability behavior. From the combined data, aromatic boronates were found to be very effective at reducing heat release and inhibiting melt flow during thermal decomposition, as were some aromatic phosphonic acid terephthalic acid and terephthalate derivatives.

Study on Preparation and Characterization of Modified Montmorillonite with the Aromatic Isocyanate

In this article, the methylene diphenyl isocyanate (MDI) containing two benzene rings was used to modify montmorillonite. The detection analysis of the original MMT and the samples after modification were investigated by infrared spectroscopy (FT-IR), x-ray diffraction (XRD) and thermo gravimetry (TG). Analysis of detection results shows that MDI and the surface of montmorillonite form chemical bonds and the spacing of montmorillonite layer increases from 1.24 nm to 1.86 nm. It provides highly active terminal isocyanate groups in situ polymerization for the montmorillonite and smart materials. It will improve the compatibility of the MMT and polymer, and allows the montmorillonite have always been able to maintain a good dispersion in polymer. Meanwhile the diphenyl isocyanate into ring can improve the heat stability of montmorillonite-modified polymer.