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Polymeric materials are increasingly used in several applications. However, their relatively high flammability presents a danger to people and property. Their use therefore requires that they are made more resistant to both the initiation and propagation of fires.In the present work we evaluate, by cone calorimeter tests, the efficiency of urea complex of magnesium and vermiculite (urea-vermiculite) as a stand-alone flame retardant in polyurethane (PU) resin and flexible polyvinyl chloride (PVC).Flexible PVC cone calorimeter tests proceeded without a visible flame following an initial short-lived ignition which degenerated into a bulk pyrolysis, in combination with a surface glowing-combustion event. Urea-vermiculite formed an exfoliated protective barrier layer which allowed thermal stabilisation of the condensed phase. The simultaneous release of halogen species by the PVC and the action of the exfoliated barrier layer prevented the formation of a flammable air–fuel mixture. The addition of urea-vermiculite lowered the peak heat release rate (pHRR) and the total heat released (tHR) significantly.In PU composites the urea-vermiculite was unable to form a cohesive protective barrier layer. The poor compatibility between the molten PU and the exfoliated flakes also led to the consumption of the underlying PU. Nevertheless, the addition of urea-vermiculite lowered significantly the pHRR of PU composites.In general, cone calorimetry results revealed that urea-vermiculite allowed thermal stabilization of the condensed phase at high temperatures but had little influence in the vapour phase behaviour. The amount of released urea’s degradation products (non-flammable vapours) was not enough to dilute the flammable vapours’ mixture. Thereby when used with PVC, which releases halogen flame poison, it showed great fire performance. [ABSTRACT FROM AUTHOR]

High density polyurethane foams have recently emerged in industry aiming to provide an innovative pattern material for the manufacture of fiber reinforced composite plastics. With the intent of understanding the constraints in the usage of such mold material for producing automotive carbon fiber parts, the present work enlightens a pre-treatment procedure to be considered including steps such as the application of sand papers, sealer, release agent and release paste wax taking into account even a study of the curing thermal cycle to produce quality parts with a negligible level of pitting taking into account the limitations inherent of the polyurethane that favor the presence of such defect. [ABSTRACT FROM AUTHOR]

In this work, impregnation with polyurethane waterborne dispersion (WPUD) was used for improving the mechanical resistance of commercial woven fabrics. Three different textiles, constituted by natural (100% linen and 100% cotton) or synthetic fibers (100% polypropylene) have been taken into account. The addition of nanosilica particles as well as of crosslinking agent in WPUD, has been also considered in order to obtain further mechanical reinforcing effects in investigated coatings. Different conditions, for optimizing the drying process in function of desired properties, have been compared. The mechanical performance of treated fabrics were evaluated in terms of perforation tests, performed on dynamometer, equipped with a blade or spike. Preliminary results confirmed an influence of polyurethane impregnation on puncture resistance of treated fabrics: in details, if an increase of spike-puncture strength was always displayed, contemporary a worsening of blade-puncture strength was shown, especially in the case of natural fabrics. Yet, the addition of nano-sized silica as well as of crosslinker gave beneficial effect on mechanical features of WPUD coated materials. In fact, these additives provided a further increase in spike punching resistance in the case of polypropylene, and certainly, a recovery in mechanical behavior of coated materials against blades. [ABSTRACT FROM AUTHOR]

The high pressure resin transfer molding (HP-RTM) process has the potential for high-volume production of continuous fiber-reinforced components in the automotive industry. The development of robust equipment, new process variants and highly reactive matrix systems lead to significant reductions of the cycle time in recent years. The paper addresses the manufacturing of carbon fiber reinforced plastic (CFRP) laminates using different matrix systems. To evaluate the matrix influence on the material properties, matrix dominated test methods were selected for evaluation of the mechanical properties. The test plates were made with the HP-RTM process at constant process parameters using carbon fiber fabrics. Only the matrix-specific supplier instructions for processing of the matrix systems (mixing ratio, temperature of components in HP-RTM equipment and mold) were varied in the study. Three Polyurethane (PU) systems and one Epoxy (EP) system were used for the characterization of the matrix dominated properties. To identify the interlaminar shear properties, two test methods were selected and compared to each other: The Short-Beam Shear (SBS) Test and the Edge Shear Test (ESH). To obtain the damage tolerance under impact loading, the energy absorptions for each material combination during instrumented drop tower tests were investigated. The results show the impact of the different Epoxy and Polyurethane matrix systems on the laminate performance. [ABSTRACT FROM AUTHOR]

Shape memory polymers (SMP) are smart materials with the ability of changing shape when subjected to external stimuli. In this work, the shape memory polyurethane (SMPU) has been synthesized via two step bulk polymerization method by replacing up to 40% molar ratio of petroleum-based polyol using palm oil-based polyols (POP). This effort was done with the purpose of reducing the usage of petroleum-based polyol due to environmental awareness. The main objective is to investigate the effects of different polyol/isocyanate/1,4-butanediol molar ratio in relation to soft-hard segment content towards the mechanical and shape memory properties of the resulting SMPU. The mechanical properties were improved with POP addition and optimum performance of tensile properties were obtained within 35 to 40% of hard segment content. Tensile strength increased with increasing POP content but after 40% of hard segment content, the properties decreased. On the other hand, the modulus significantly reduced with an increase of hard segment content. Crystallinity also decreased with decreasing of polycaprolactone diol (PCL) content as more POP content was added. Shape memory properties of PU 165 is better than PU 154 in terms of the ability to return to its original shape since all of PU 165 samples showed 100% recovery. In general, the addition of palm oil-based polyol showed improvement in mechanical and shape memory properties as compared to pristine SMPU. [ABSTRACT FROM AUTHOR]

Rigid polyurethane (PU) biocomposite foam had been successfully prepared by reacting palm oil-derived polyol (PO-p) with polymeric 4, 4-diphenylmethane diisocynate (p-MDI). Two types of alkali-treated oil palm fibres namely, empty fruit bunch (EFB) and palm pressed fibre (PPF) were used as fillers to be incorporated into PU foam at 2.5 wt%, 5 wt% and 7.5 wt% fibre loadings. The effects of these fibres on surface morphology, compressive strength and thermal transition behaviours of biocomposite foams were investigated. Fourier transform infra-red (FTIR) analysis confirmed the formation of urethane linkages (-NHCOO) in all samples at 1530-1540 cm-1. Differential scanning calorimetry (DSC) analysis showed the average melting peak temperature (Tm) of biocomposite foams (132°C) were lower Tm than that of pure PU foam (161.67°C) and the increase amount of fibres did not give significant effect on the Tm of both biocomposite systems. Meanwhile, the microscopic images of PU-PPF foams exhibited smaller and uniform cell size morphologies compared with the PU-EFB foams that had coarse and irregular cell sizes, especially at 7.5wt% EFB. These findings were manifested with the gradually increase of compressive strength of PU- PPF at all PPF ratios while for PU-EFB system, the compressive strength increased up to 5 wt% before reduced at 7.5 wt% loading. It was thought due to the residual oil in PPF fibre had plasticized the PU matrix to a little extent, thus helping the dispersion of PPF fibre across the matrix. [ABSTRACT FROM AUTHOR]

In this study, polyurethane (PU) film was prepared from palm kernel oil-based polyester (PKO-p) via prepolymerization with isocyanate/polyol group ([NCO/OH]). PU films were physically characterized to investigate the mechanical properties, thermal behavior, water uptake, water vapor transmission rates as well as biocompatibility and antibacterial activities against Gram-positive (Staphylococcus aureus) and Gram-negative bacteria (Escherichia coli). Results showed that PU 2 film exhibited optimum mechanical performance and thermal properties with the water vapor transmission rates at 267 ± 17 g m-2 d-1, comparable to commercial dressing. Biocompatibility studies revealed that PU films were non-cytotoxic to the human skin fibroblast cells (CRL2522) and exhibited bactericidal effect against both bacteria. [ABSTRACT FROM AUTHOR]

Polyurethane modified epoxy based on glycerol monooleate (PME-GMO) was synthesized. GMO as polyol for synthesis of PME-GMO was synthesized via Fisher Esterification between oleic acid from palm oil and glycerol by using sulfuric acid as catalyst with time variation i.e. 3, 4, 5 and 6 hours at 160°C. Characterizations of GMO were carried out by analysis of acid number, hydroxyl value and FTIR. The data show that the conversion of oleic acid to ester compound is directly proportional with the increasing of reaction time but the enhancement is not significant after 3 hours. Furthermore, GMO product was used as polyol for modification of epoxy with polyurethane. Modification of epoxy with polyurethane was performed by reacted epoxy, tolonate and GMO simultaneously in one step. In this research, the reaction condition was varied i.e. time reaction (0.5; 1; 1.5; 2; 2.5 hours), composition of polyurethane used (10%, 20% toward epoxy) and rasio of tolonate and GMO (NCO/OH ratio) as component of polyurethane (1.5 and 2.5). Characterization of polyurethane modified epoxy based on glycerol (PME-GMO) was conducted by viscosity and FTIR analysis. The viscosity of PME-GMO increased with increasing of reaction time, polyurethane composition and NCO/OH ratio. [ABSTRACT FROM AUTHOR]

Nowadays, variety of biomaterials may be used to produce implanted scaffolds such as metal-based, ceramicbased and polymer-based materials. In this study, porous bioactive glass (BG) reinforced polyurethane (PU) composite scaffolds with different PU:BG mass ratio (10 to 40 wt%) were fabricated as a potential candidate for synthetic bone graft. The PU-BG scaffolds were prepared using solvent casting combined with salt leaching (SCPL) method and were subjected to several characterizations including fourier transform infra-red (FTIR) spectroscopy, scanning electron microscopy (SEM) and energy dispersive x-ray spectroscopy (EDX). FTIR spectrum showed the trace of BG particles in the PU-BG scaffolds with high concentration of BG (30 and 40 wt%). EDX confirmed that the white particles in the PU-BG scaffold as observed via SEM micrograph were BG particles. A slightly round and irregular pore structures were observed for the PU-BG scaffolds prepared in this study. More homogeneous pore structures were observed as the amount of BG in the PUBG scaffold is increased. The overall pore size for all scaffolds was in the range of 130 to 400 µm which is suitable for the growth of bone tissue. [ABSTRACT FROM AUTHOR]

Polyurethane (PU) has a unique structure that is dependent on the structure of the starting material used. This research focused on investigating the role of isocyanate groups (NCO) in the determination of the viscoelastic properties of the polymer. Monoester polyol was reacted with three different diisocyanates separately by prepolymerization method. The diisocyanates used were 2,4-diphenyl methane diisocyanate (MDI), toluene 2,4-diisocyanate (TDI) and isophoronediisocyanate (IPDI). Acetone was used as a solvent. IPDI, MDI and TDI were reacted with monoester polyol at ratios of 10:9, 10:10, 10:12 and 10:14 (polyol:diisocyanate). Then, the PU foams produced by the curing process were analyzed by Fourier Transform infrared spectroscopy (FTIR). The FTIR spectra showed the presence of the amide peak (-NH) and the absence of hydroxyl peak (-OH) indicated that the reaction between polyol and diisocyanate has occurred. However, the soxhlet extraction showed that only MDI-based PUs contain crosslinking bond. These cross-linking bond at the ratio of 10:10, 10:12 and 10:14 were 41.3%,61.1% and 74.1% respectively. Thermal properties of the PU foams were determined by differential scanning calorimetry (DSC) and thermogravimetry (TGA) techniques. MDI-based PUs and TDI-based PUs show two values of Tg while IPDI-based PUs only show one Tg value. The tensile strains of PU foams decreased with increasing ratio of isocyanate. Meanwhile, PU foams with ratio of polyol to isocyanate at 10:12 showed the highest tensile stress and modulus compared to at 10:10 and 10:14. [ABSTRACT FROM AUTHOR]

A series of modification polyurethane (PU) system was prepared by introducing palm kernel based polyol (PKO-p) to progressively replaced commercial polyether polyol from petrochemical based material. This paper describes the effect of PKO-p on the physical-mechanical properties of polyurethane foams. Stress-strain analysis in tensile mode was conducted with physicochemical analysis by performing Fourier transform infrared (FTIR). The morphological studies were observed by the optical microscope. The foam showed an increment on the modulus up to 458.3kPa as more incorporation of PKO-p introduced to the system. In contrast, tensile strength of PU foam depicted the highest up to 162 kPa at 60:40. The elongation at break showed decrement as the composition of the renewable polyol increased to a ratio 60/40 of PKO-p to petrochemical based polyol. [ABSTRACT FROM AUTHOR]

Palm-based polyurethane (pPU) with varying lithium salt (LiClO4) content was synthesized. Higher loading percentage of LiClO4 in the pPU led to the inhibition of prepolymerization process from taking place. Hydrogen bonded C=O was detected in the FTIR spectrum indicating the hydrogen bonding between the urethane bonds. Ordered complexed C=O was observed in the FTIR spectrum confirming the complex formation between urethane bond and Li+ ion. DSC thermogram showed the increase in the LiClO4 content could increase the glass transition temperature. SEM micrographs exhibited that more bubbles were formed when the LiClO4 increased from 10 to 30wt% indicating the reaction between free isocyanate groups with moisture presence in the salt due to the hygroscopic properties of LiClO4. [ABSTRACT FROM AUTHOR]

The dispersion of multi-walled carbon nanotubes in thermoplastic polyurethanes has been done in co-rotative twin screw extruder through a melt blending process. A specific experimental design was prepared taking into account different compounding parameters such as feeding, temperature profile, screw speed, screw design, and carbon nanotube loading. The obtained samples were characterized by thermogravimetric analysis (TGA), light transmission microscopy, dynamic rheometry, and dynamic mechanical analysis. The objective of this work has been to study the dispersion quality of the carbon nanotubes and the effect of different compounding parameters to optimize them for industrial scale-up to final applications. [ABSTRACT FROM AUTHOR]

In this paper the static electric field induced strain, dielectric and mechanical properties of polyurethane elastomer films with different thicknesses were investigated. © 2007 American Institute of Physics [ABSTRACT FROM AUTHOR]