Some properties of polypropylene filled with metal fibers

Polypropylene/steel fiber composites were prepared and tested for mechanical, electrical, and permeability performance. To enhance adhesion of polypropylene to steel fibers, two kinds of coupling agents, maleated polypropylene wax and maleated polypropylene, were used. It was found that maleated polypropylene wax was more effective. However, as indicated by permeability measurements and scanning electron microscopy (SEM), adhesion was rather poor. Oxygen and water vapor permeabilities of the polypropylene/steel fiber composites increased with the steel fiber concentration. The lack of adhesion at the fiber-polymer interface created diffusive paths for the gas to penetrate the composite. Addition of polyamide to polypropylene caused a decrease in the permeability of the system, due to a reduction of the permeability of the matrix. The polypropylene/steel fiber composites become conductive at a volume loading of about 10 percent. At this concentration the volume resistivity of the composite is 10.8 ohm cm.     

Comparative spectroscopic study of the modification of cellulosic materials with different coupling agents

The reactions of two cellulosic materials (an industrial cellulosic by‐product from a Kraft pulp mill facility and a reference material) with three coupling agents, used to improve compatibility between cellulosic reinforcements and thermoplastic matrices, were studied by diffuse reflectance Fourier‐transform infrared (DRIFT) spectroscopy and diffuse reflectance ultraviolet‐visible spectroscopy. A maleated polypropylene wax (Epolene E‐43™) and two silanes (N‐2‐aminoethyl‐3‐aminopropyltrimethoxysilane and methyltrimethoxysilane) were used as coupling agents. The two cellulosic materials reacted in a similar way and the three coupling agents were covalently bonded to the cellulose. For the aminosilane, a reaction with cellulose involving a fraction of the amino groups was detected. A simple method, based on the analysis of the oxidation kinetics of treated and untreated materials, was developed to compare the degree of cellulose modification achieved by each coupling agent. The analysis revealed that a reduced fraction of the cellulose reactive groups was converted by esterification with the maleated polypropylene. However, when applied in the appropriate conditions, the two silanes converted most of such cellulose reactive groups. Finally, the reaction of cellulose with mixtures of coupling agents was studied. The aminosilane‐treated cellulose reacted with the maleated polypropylene with formation of amide links. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 75: 256–266, 2000     

Polypropylene–wood fiber composites: Effect of treatment and mixing conditions on mechanical properties

Polypropylene/wood fiber composites were prepared at three different temperatures: 170°C, 180°C, and 190°C. The surface of wood fibers was modified through the use of silane coupling agents and/or coating with polypropylene or maleated polypropylene. The fiber coating was performed by propylene polymerization in the presence of wood fibers or by immersion in an o-dichlorobenzene polypropylene (or maleated polypropylene) solution. Tensile and three-point bending tests were performed in order to evaluate the adhesion between matrix and wood fibers. Evidence shows that 180°C is the best mixing temperature, while the use of vinyl-tris (2-methoxy ethoxy) silane with or without maleated polypropylene coating is the best surface treatment. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 65:1227–1235, 1997     

Advances in maleated polyolefins for plastics applications

The objective of the paper is three-fold, covering the use of maleated polyolefins as chemical coupling agents, compatibilizers, and impact modifiers. Introduction of a new chemical coupling agent for glass reinforced polypropylene details its improved properties versus current systems. Discussion of impact modifiers includes three developmental impact modifiers that combine higher melt flow properties and good room temperature notched Izod properties. The third area details the property improvements obtained in nylon/polypropylene blends through compatibilization with a maleated polyolefin.     

Thermal,viscoelastic and adhesion properties of EVA (ethylene-co-vinyl acetate) hot melts containing polypropylene waxes of different nature

Wax determines the compatibility of tackifier and polymer in hot melt adhesives. Although the influence of the addition of microcrystalline and Fischer-Tropsch waxes on the properties of ethylene-co-vinyl acetate (EVA) hot melts has been studied, the addition of polypropylene wax has not been considered yet. In this study, different polypropylene waxes (polypropylene wax – PP, – maleic anhydride grafted polypropylene wax – PPMA – copolymer of polypropylene and 10.9?wt.% polyethylene wax – PP-E) were added to EVA hot melts and they were characterized by Brookfield viscosity, softening point measurement, differential scanning calorimetry, thermal gravimetric analysis, dynamic mechanical thermal analysis, plate–plate rheology, tack, and single-lap shear adhesion. The viscosities of EVA hot melts containing polypropylene waxes were relatively high, the highest viscosity corresponded to the formulation containing PP-E wax which also showed pseudoplasticity. The change in viscoelastic properties (i.e., from dominantly viscous to dominantly elastic) was produced at lower temperature in EVA hot melt containing PP-E wax, this adhesive exhibited the highest tack. On the other hand, the addition of acrylic PPMA wax increased the adhesion of EVA hot melt but lower tack was obtained. Finally, the PP-E wax was more compatible with EVA copolymer than the other polypropylene waxes.     

Effects of coupling agents on the oxidation and darkening of cellulosic materials used as reinforcements for thermoplastic matrices in composites

Oxidation and darkening occur during the processing of composites made from thermoplastic matrices and cellulosic reinforcements. We have studied the effects of several coupling agents on both the oxidation and darkening of cellulosic materials at temperatures close to those used in the processing of cellulose‐reinforced thermoplastics. A maleated polypropylene wax (Epolene E‐43^TM) and two silanes (N‐2‐aminoethyl‐3‐aminopropyltrimethoxy silane and methyltrimethoxysilane) were used as coupling agents. Oxidation was measured by Diffuse Reflectance Infrared Fourier Transform (DRIFT) spectroscopy. Standard colorimetry was used to measure darkening. Coupling agent effects depend on the nature and extent of cellulose modification achieved by treatments and the nature of the coupling agent. Epolene wax E‐43 produced scarce effects on both the oxidation and darkening of cellulosic materials at 200°C. Only for longer oxidation times was an increase in oxidation and darkening observed in E‐43‐treated samples. Silane coupling agents inhibited the formation of carbonyl and carboxyl groups for shorter oxidation times. The diaminosilane produced a stronger darkening, probably due to a chemical reaction that generated new chromophores containing C? N bonds.     

Mechanical and morphological properties of wood plastic composites based on municipal plastic waste

Production and characterization of wood plastic composites (WPC) from the light fraction of municipal plastic wastes (post‐consumer) and wood processing residues (sawdust) were investigated. Composition analysis revealed the presence of polyethylene (PE) and polypropylene (PP) as the two main components of the matrix. In order to improve compatibility and adhesion between all the phases, an ethylene–octene copolymer was used to compatibilize the polymer phases and was also acting as an impact modifier, while the addition of maleated polyethylene and maleated polypropylene (MAPP) were acting as coupling agents between the polymer matrix and the wood flour. The combined effect of all the components was found to produce composites with interesting morphological (dispersion and adhesion) and mechanical properties (tension, torsion, flexion, and impact) after optimization of the additive package (blend of coupling agents). POLYM. COMPOS., 2013. © 2013 Society of Plastics Engineers     

Controlled interactions in cellulose-polymer composites. 1: Effect on mechanical properties

The surface properties of cellulose fibers have been modified by heat treatment, by silane coupling agents, and by maleated polypropylene grafts. The effectiveness of these methods has been evaluated by electron spectroscopy (ESCA), by contact angle measurements, and by inverse gas chromatography. The latter analyses yielded information on the fibers' acid/base interaction potential. Cellulose was found to be amphoteric, with prevalent acidic properties. Heat and chloro-silane treatments accentuated acidity, while amino-silane treatment produced net basicity in the fiber surface. Modification with maleated polypropylene reduced specific interactions and converted the fiber to a predominantly dispersion-force solid. The modified fibers were used in composites with polypropylene (neutral), polystyrene (base), and chlorinated polyethylene (acid) as matrix. Stress/strain and dynamic mechanical parameters were found to vary with acid/base interactions between polymer and fiber, significant improvements being noted in elastic and storage moduli, in tensile strength and elongation. In polypropylene, properties were unaffected by acid/base considerations. Acid/base forces, not necessarily dominant, merit consideration in the design of surface modification strategies intended to optimize composite mechanical properties.     

Rice husk/poly(propylene‐co‐ethylene) composites: Effect of different coupling agents on mechanical,thermal, and morphological properties

Poly(propylene‐co‐ethylene) composites with rice husk were prepared in a corotating intermeshing twin‐screw extruder using four different coupling agents. While modified maleic anhydrides such as maleated polypropylene (MAPP) and maleated polyethylene (MAPE) are commonly used as compatibilizers to improve interfacial adhesion between lignocellulosic filler and matrix, in this study, polypropylene grafted with acid comonomer (CAPP) and high‐density polyethylene grafted with acid comonomer (CAPE) were also used. The morphologies and the thermal and mechanical properties of the composites were characterized using scanning electron microscopy, thermogravimetric analysis, differential scanning analysis, tensile and impact tests. The results indicate that the base resin of the compatibilizer is an important factor in determining the effectiveness of compatibilizers for composites. Composites with PP‐based compatibilizers are more effective than PE‐based compatibilizers due to the improved wetting of the former compatibilizer in the matrix polymer. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Mechanical properties of virgin and recycled polyolefin‐based composite laminates reinforced with jute fabric

Polyolefin‐based composite laminates reinforced with jute fabric were prepared by compression molding and investigated in terms of flexural properties and impact behavior. The use of a virgin polypropylene as the matrix was compared with two polyolefin matrices coming from discarded car bumpers and selected packaging wastes, respectively, and mainly constituted by mixtures of polyethylene and polypropylene resins. The influence of a coupling agent (maleated polypropylene) was always considered in order to improve the interfacial adhesion and, consequently, the composite strength. The effect of this coupling agent, clearly dependent on the amount of polypropylene phase in the overall mixture, was found to be satisfactory only in the case of virgin polypropylene‐based systems. These latter, in presence of maleated polypropylene, have shown higher flexural parameters, lower propagation energy and higher breaking impact load with respect to uncompatibilized ones. Results were supported by morphological observations of impact surfaces, always highlighting a poor adhesion at the reinforcement–matrix interface except in compatibilized virgin polypropylene‐based laminates. POLYM. COMPOS., 36:2022–2029, 2015. © 2014 Society of Plastics Engineer     

Further Investigations on Cane Wax Refining and Bleaching

The crude wax from Egyptian sugar contains ash, which probably consists of soaps and phosphatides. After the inorganic material has been eliminated by heating with hydrochloric acid, a soft wax of higher acidity remains. The acid and the softer components of the wax may be readily distilled under low pressure in steam, leaving as a residue a hard dark wax, which is odourless, contains little acid material and is comparable with hard, dark waxes obtained by solvent process of refining. The distillates from the low pressure distillation are pale yellow-brown pastes. The effect of different chemical bleaching agents on bleaching of hard wax is reported. Chromic acid was found to be much superior to other bleaching agents examined. The hard wax obtained, whether from the low pressure refining or from solvent refining, are readily converted by this agent into pale hard, glossy waxes having high acid values.     

Modern dispersing agents for polypropylene

Dispersing agents are becoming indispensable for the effective colouring of polypropylene. Reinhold Kling and Dr. Reiner Hess of Clariant GmbH describe the development of modern dispersing agents - micronized waxes and metallocene waxes.     

Organogel Formation of Soybean Oil with Waxes

Many waxes including plant waxes and animal waxes were evaluated for the gelation ability toward soybean oil (SBO) and compared with hydrogenated vegetable oils, petroleum waxes and commercial non-edible gelling agents to understand factors affecting the gelation ability of a gelator. Sunflower wax (SW) showed the most promising results and all SW samples from three different suppliers could make a gel with concentrations as low as 0.5 wt%. Candelilla wax and rice bran wax also showed good gelation properties, which, however, varied with different suppliers. Gelation ability of a wax is significantly dependant on its purity and detailed composition. A wax ester with longer alkyl chains has significantly better gelation ability toward SBO than that with shorter alkyl chains indicating that the chain length of a component in a wax such as wax ester is an important factor for gelation ability. The SW–SBO organogel showed increased melting point with increased SW content, showing the melting point range from about 47 to 65 °C with 0.5–10 wt% SW. The effects of cooling rate on crystal size and firmness of a gel were investigated. The dependence of firmness on cooling rate was so significant that the desired texture of an organogel could be achieved by controlling the cooling rate in addition to controlling the amount of gelling agent. This research reveals that a small amount of food grade plant waxes including SW may replace a large amount of the hardstock containing trans-fat or saturated fat.     

Deformation mechanisms and mechanical properties of modified polypropylene/wood fiber composites

Mechanical properties and deformation mechanisms of polypropylene (PP)/wood fiber (WFb) composites modified with maleated polypropylene as compatibilizer and styrene-butadiene rubber (SBR) as impact modifier have been studied. The addition of maleated polypropylene to the unmodified polypropylene/wood fiber composite enhances the tensile modulus and yield stress as well as the Charpy impact strength. SBR does not cause a drop in the tensile modulus and yield strength because of the interplay between decreasing stiffness and strength by rubber modification and increasing stiffness and strength by good interfacial adhesion between the matrix and fibers. The addition of both maleated polypropylene and rubber to the polypropylene/wood fiber composite does not result in an improvement of effects based on maleated polypropylene and rubber, which includes possible synergism. The deformation mechanisms in unmodified polypropylene/wood fiber composite are matrix brittle fracture, fiber debonding and pullout. A polymeric layer around the fibers created from maleated polypropylene may undergo debonding, initiating local plasticity. Rubber particle cavitation, fiber pullout and debonding were the basic failure mechanisms of rubber-toughened polypropylene/wood fiber composite. When maleated polypropylene was added to this composite, fiber breakage and matrix plastic deformation took place. Polym. Compos. 25:521–526, 2004. © 2004 Society of Plastics Engineers.     

Waxes in the candle industry

Summary 1. The waxes in use for candles consist of paraffin and, in special cases, of beeswax. 2. Stearic acid is the only known hardening agent for paraffin. It raises the bending (softening) point and lowers the melting point. It can be used in any quantity without impairing the burning quality of the candle. 3. No other wax, natural or synthetic, can be substituted for stearic acid as a hardening agent for candle stock. Other waxes generally injure the burning quality of the candle or fail to produce any improvement, being at the same time more expensive than stearic acid. 4. The hydrogenated oils and fats serve as hardening agents for paraffin, especially for scale paraffin wax, and are used chiefly for candles which are consumed in glasses. 5. Synthetic or natural resins can be used in form of coatings only and are used chiefly for decorative candles. 6. No known synthetic hardening agent for candle wax can be satis-factorily substituted for stearic acid, even in such a mixture as 95% paraffin (MP 135°) and 5% stearic acid.     

Influence of processing conditions and material compositions on the performance of formaldehyde‐free wood‐based composites

This study examined the differences between formaldehyde‐free wood composite panels made with maleated polyethylene (MAPE) and maleated polypropylene (MAPP) binding agents. Specifically, the study investigated the contrasts of (a) base resin type, PE vs. PP, (b) molecular weight/maleic anhydride content in MAPP binding agents, and (c) the manufacturing methods (reactive extrusion vs. hot press) on the physicomechanical properties of the composites. FTIR and XPS analyses of unmodified and modified wood particles after reactive extrusion with maleated polyolefins provided evidence of chemical bonding between the hydroxyl groups of wood particles and maleated polyolefins. Although extruding the particles before panel pressing gave better internal bond (IB) strength, superior bending properties were obtained through compression molding alone. MAPP‐based panels outperformed MAPE‐based panels in stiffness. Conversely, MAPE increased the IB strength of the panels compared with MAPP. Polymer base resin had no effect on modulus of rupture or screw holding capacity. Differences between the two maleated polypropylene compounds were not significant for any of the mechanical properties tested. Formaldehyde‐free wood composites manufactured in this study often outperformed standard requirements for conventional particleboard, regardless of material composition or manufacturing method used. POLYM. COMPOS., 27:599–607, 2006. © 2006 Society of Plastics Engineers     

Comparison of the effects of polyethylenimine and maleated polypropylene coupling agents on the properties of cellulose‐reinforced polypropylene composites

The desire to improve the properties of cellulose‐reinforced composites while producing them by methods as similar as possible to those used on an industrial scale is one of the driving forces in this field of research. In this work, extensive research for determining the mechanical, thermal, rheological, and physical properties of novel cellulose‐reinforced polypropylene composites containing a polyethylenimine (PEI) coupling agent was conducted. A comparison of their properties with those of reference composites without any coupling agent or containing a maleated polypropylene (MAPP) coupling agent was also carried out. The presence of the PEI coupling agent mainly gave rise to a substantial increase in the tensile and flexural strengths and elongations as well as the impact strength, heat deflection temperature (HDT), melt volume flow index, and water absorption of PEI‐containing composites in comparison with composites without any coupling agent added. However, the increases achieved in the tensile and flexural composite strengths and HDT were lower than those achieved with the MAPP coupling agent mainly for composites containing 50 wt % cellulose fibers. On the other hand, PEI‐containing composites exhibited, in most cases, larger elongations and energies required to break in tensile tests as well as larger impact strengths, melt volume flow indices, and water absorption percentages than MAPP‐containing composites. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Helle Montanwachs-Derivate

Light Coloured Montana Wax Derivatives Light coloured or almost colourless montana wax derivatives are obtained by careful bleaching of raw montana wax with varying amounts of chromic acid according to a new process. In these products, the ratio of wax acid to wax ester differs from the well-known products obtained by oxidation. The characteristic physical and chemical data are compared, and their impact on practical properties, such as emulsion formation with water, formation of wax/solvent mixtures, and compatibility with other waxes, is shown. The light coloured products obtained by oxidation of raw montana wax can be used as raw materials for cleansing agents and cosmetics, and as auxiliaries for the processing of plastics.     

Separation of some paraffin wax grades using solvent extraction technique

Solvent extraction technique has been used to separate paraffin wax grades; with different characteristics; from El-Ameria light, middle and heavy slack waxes. The wax deoiling has been done by solvent extraction at different extraction temperatures and different solvent feed ratios (S/F by weight). The extraction solvents used are furfural, N-methyl-2-pyrrolidone (NMP) and N, N, dimethylacetamide (DMA). The wax products are evaluated according to TAPPI-ASTM equation and petroleum wax specifications. The data revealed that DMA and NMP are suitable extracting solvents for isolating of semi- and scale-refined grades of paraffin waxes from light and middle slack waxes. But furfural solvent can separate only semi-microcrystalline waxes from heavy slack wax.     

Natural montan wax and its raffinates

Natural waxes have been used by mankind since prehistoric times. Many uses of wax are based on the imitation of its natural functions. Waxes in nature primarily serve to provide protective barriers on the surfaces of living organisms. Their functions are also determined by wax characteristics such as adhesion and cohesion, as well as slip and deformation effects. In ancient times, for example, wax seals were used to help preserve food and beverages. Beeswax has remained an important material for manufacturing candles up to the present day. Recent vegetable waxes have been used in industry since the mid‐nineteenth century, for example in care products. Refined and chemically processed montan‐based waxes are quite similar to naturally occurring vegetable ester waxes in their structure and application characteristics. They are similar in their environmental characteristics and are also nontoxic. Crude montan wax itself belongs to the naturally occurring waxes of vegetable origin such as candelilla wax and carnauba wax.