The unidirectional glass fiber reinforced furfuryl alcohol for pultrusion. II. Correlation of processing parameters for optimizing the process

Unidirectional glass fiber reinforced furfuryl alcohol (FA) composites have been prepared by the pultrusion processes. The optimum processing parameters of the glass fiber reinforced FA composites by pultrusion has been studied. The effects of the optimum processing parameters on the properties (flexural strength, flexural modulus, notched Izod impact strength, glass transition temperature (T_g), dynamic shear storage modulus (E'), shrinkage ratio, and roughness) investigated including die temperature, pulling rate, postcure temperature and time, and filler type and content. Results show that the pultruded composites possessed various optimum pulling rates at different die temperatures. On the basis of the DSC diagram, the swelling ratio and the mechanical properties of pultruded composites, the optimum die temperature can be determined. The mechanical properties and T_g increase at a suitable postcure temperature and time. Furthermore, the properties which decrease due to the degradation of pultruded composites for a long postcure time will be discussed. The mechanical properties of pultruded composites reach a maximum value at various filler content corresponding to the talc and calcium carbonate, respectively, and then decreased. When the fillers are added to the pultruded glass fiber reinforced FA composites, the shrinkage ratio of composites become smaller, and the surface of composites became smooth. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Pultruded fiber-reinforced poly(methyl methacrylate) composites. I. Effect of processing parameters on mechanical properties

A feasibility study of pultrusion of fiber-reinforced thermoplastic PMMA composite has been conducted using a proprietary method. Effect of processing parameters, preparation of methyl methacrylate (MMA) prepolymer on the mechanical properties (tensile, flexural strength and modulus, impact strength, etc.) of fiber-reinforced PMMA composites by pultrusion has been studied. Processing parameters investigated included pulling rate, die temperature, postcure time and temperature, and filler content. From the study of Brookfield viscometer and FTIR spectrum the processing conditions can be defined. It was found from SEM photographs that the wetting out of fibers by PMMA resin was complete, and the fiber bundles were distributed evenly in the PMMA matrix. From the study of ¹H-NMR, GPC, and Brookfield viscometer, the conversion, molecular weight, and viscosity of MMA prepolymer data were obtained. From the DSC diagram, molecular weight measurement, and the rule of polymerization rate, the optimum die temperature was determined. It was found that the mechanical properties increase with increasing filler content and postcure temperature, and with decreasing die temperature and pulling rate.     

In‐situ pultrusion of urea‐formaldehyde matrix composites. II: Effect of processing variables on mechanical properties

Unidirectional fiber reinforced urea‐formaldehyde (UF) composites have been prepared by the pultrusion processes. The effects of the processing parameters on the mechanical properties (flexural strength and flexural modulus, etc.) of the glass fiber reinforced UF composites by pultrusion has been studied. The processing variables investigated included die temperature, pulling speed, postcure temperature and time, filler type and content, and glass fiber content. The die temperature was determined from differential scanning calorimetry (DSC) diagram, swelling ratio, and mechanical properties tests. It was found that the mechanical properties increased with increasing die temperature and glass fiber content, and with decreasing pulling rate. The die temperature, pulling speed, and glass fiber content were determined to be 220°C, 20–80 cm/min, and 60–75 vol%, respectively. The mechanical properties reached a maximum value at 10, 5, 5, and 3 phr filler content corresponding to the kaolin, talc, mica, and calcium carbonate, respectively, and then decreased. The mechanical properties increase at a suitable postcure temperature and time. Furthermore, the properties that decreased due to the degradation of composite materials for a long postcure time are discussed. POLYM. COMPOS., 27:8–14, 2006. © 2005 Society of Plastics Engineers     

The development of glass fiber reinforced polystyrene for pultrusion. I: Process feasibility,dynamic mechanical properties,and postformability

A feasibility study on the pultrusion of a glass fiber reinforced polystyrene (PS) has been conducted using a proprietary method. The styrene prepolymer synthesized in this study was prepared from blends of styrene monomer and benzoyl peroxide (BPO). The process feasibility, dynamic mechanical properties, and postformability of the glass fiber reinforced PS by pultrusion have been investigated. By means of gel permeation chromatography, ¹H nuclear magnetic resonance (¹H-NMR), and a Brookfield viscometer, the molecular weight, conversion, and viscosity of the styrene prepolymer were obtained. From the investigations of the long pot life of styrene prepolymer, the high reactivity of styrene prepolymer, and excellent fiber wet-out, it was found that the PS resin showed excellent process feasibility for pultrusion. The dynamic storage modulus (E') of pultruded glass fiber reinforced PS composites increased with increasing die temperature, filler content, postcuring and glass fiber content, and with decreasing pulling rate. The composite can be postformed by thermoforming under pressure, and mechanical properties of postformed composites can be improved.     

In situ pultrusion of urea–formaldehyde matrix composites. I. Processability,kinetic analysis,and dynamic mechanical properties

We conducted a feasibility study on the pultrusion of a glass‐fiber‐reinforced urea–formaldehyde (UF) composite using a proprietary method. The UF prepolymer synthesized in this study was prepared from blends of UF monomer and a curing agent (NH₄Cl).The process feasibility, kinetic analysis, and dynamic mechanical properties of the glass‐fiber‐reinforced UF composites by pultrusion were investigated. From investigations of the long pot life of the UF prepolymer, the high reactivity of the UF prepolymer, and excellent fiber wet‐out, we found that the UF resin showed excellent process feasibility for pultrusion. A kinetic model, dα/dt = A exp(?E/RT)α^m(1 ? α)ⁿ, is proposed to describe the curing behavior of a UF resin. Kinetic parameters for the model were obtained from dynamic differential scanning calorimetry scans with a multiple‐regression technique. The dynamic storage modulus of the pultruded‐glass‐fiber‐reinforced UF composites increased with increasing die temperature, filler content and glass‐fiber content and with decreasing pulling rate. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 1242–1251, 2002     

Pultruded fiber reinforced thermoplastic poly(methyl methacrylate) composites. Part I. Correlation of processing parameters for optimizing the process

The effect of processing parameters on the properties (tensile, flexural strength and modulus and impact strength, etc.) of pultruded fiber reinforced poly(methyl methacrylate) (PMMA) composites has been studied. The processing parameters investigated included pulling rate, die temperature, and postcure. Wetting of fibers by PMMA resin was complete, and the fiber bundles were evenly distributed in the PMMA matrix. The conversion, molecular weight and viscosity of MMA prepolymer were studied by ¹H-NMR, GPC and Brookfield viscometer. The optimum die temperature was determined from DSC diagram, molecular weight measurement and from the polymerization rate. The mechanical properties increased with the increasing postcure temperature and decreasing pulling rate and die temperature.     

Mathematical model for the pultrusion of blocked PU–UP matrix composites

The thermokinetic behavior of blocked polyurethane (PU)–unsaturated polyester (UP)–based composites during the pultrusion of glass‐fiber‐reinforced composites was investigated utilizing a mathematical model that accounted for the heat transfer and heat generation during curing. The equations of continuity and energy balance, coupled with a kinetic expression for the curing system, were solved using a finite difference method to calculate the temperature profiles and conversion profiles in the thickness direction in a rectangular pultrusion die. A kinetic model, dP/dt = A exp(?E/RT)P^m(1 ? P)ⁿ, was proposed to describe the curing behavior of a blocked PU–UP resin. Kinetic parameters for the model were obtained from dynamic differential scanning calorimetry scans using a multiple regression technique, which was able to predict the effects of processing parameters on the pultrusion. The effects of processing parameters including pulling speed, die wall temperature, and die thickness on the performance of the pultrusion also were evaluated. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 1996–2002, 2003     

Dynamic mechanical properties of short carbon fiber-filled styrene–isoprene–styrene block copolymer

The mechanical and dynamic mechanical properties of short carbon fiber-filled styrene–isoprene–styrene (S–I–S) block thermoplastic elastomeric composite have been studied. Brabender mixing followed by milling of the fiber–rubber compositions caused about a 30-fold decrease in the fiber aspect ratio and random fiber orientation. Although low-strain moduli increased on fiber incorporation, tensile and tear properties dropped and anisotropy in mechanical properties was not observed. Tan δ values at the T_g region decreased on filler incorporation, but at room temperature, the tan δ values increased with filler loading. The variation of storage moduli and tan δ values with frequency followed a pattern similar to the variation of these properties with filler incorporation. © 1993 John Wiley & Sons, Inc.     

Pultruded fiber-reinforced poly(methyl methacrylate) composites. II. Static and dynamic mechanical properties,environmental effect,and postformability

This paper presents a novel process developed to manufacture poly(methyl methacrylate) (PMMA) pultruded composite. The mechanical, thermal, and dynamic mechanical properties, environmental effect, postformability of various fiber (glass, carbon, and Kevlar 49 aramid fiber) reinforced pultruded PMMA composites have been studied. Results show mechanical properties (i.e., tensile strength, specific tensile strength, tensile modulus, and specific flexural strength) and thermal properties (HDT) increase with fiber content. Kevlar fiber/PMMA composites possess the highest specific tensile strength and HDT, carbon fiber/PMMA composites show the highest tensile strength and tensile modulus, and glass fiber/PMMA composites show the highest specific flexural strength. Pultruded glass-fiber-reinforced PMMA composites exhibit good weather resistance. These composite materials can be postformed by thermoforming under pressure, and mechanical properties of postformed products can be improved. The dynamic shear storage and loss modulus (G′, G″) of pultruded glass-fiber-reinforced PMMA composites increased with decreasing pulling rate, and their shear storage moduli are higher than those of pultruded Nylon 6 and polyester composites.     

Sugarcane bagasse composites from vegetable oils

Sugarcane bagasse composites have been prepared by the free radical polymerization of regular or modified vegetable oils with divinylbenzene and n‐butyl methacrylate in the presence of dried, ground sugarcane bagasse. Various cure times and temperatures have been investigated to determine the optimum cure sequence for the new materials. The postcure time has also been varied, and an ideal postcure treatment of 1 h at 180°C at ambient pressure has given the best overall properties. The effect of varying the filler load and resin composition has been assessed by means of tensile tests, dynamic mechanical analysis, thermogravimetric analysis, Soxhlet extraction, followed by proton nuclear magnetic resonance spectroscopic analysis of the extracts, and scanning electron microscopy. It has been observed that the initial washing and drying of the filler influence the filler–resin interaction and impact the final properties of the composites. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Fiber reinforced nylon-6 composites produced by the reaction injection pultrusion process

Reaction injection pultrusion (RIP) combines the injection pultrusion process with reaction injection molding (RIM) techniques to yield one of the more novel methods of thermoplastic matrix pultrusion. An experimental set-up was designed and built to pultrude nylon-6 RIM material and continuous E-glassfiber. Well-impregnated nylon-6 composites with 66.5, 68.8, 71.1, and 73.3 vol% fiber were produced. Internal temperature profile within the die was recorded during the process, and physical properties of resulting composites were measured. This paper presents results of the effect of fiber content, die temperature profile and pulling speed variations on internal temperature profile, monomer conversion, and physical properties. The study showed that increasing pulling speed lowered both peak temperature and monomer conversion. Higher die temperatures accelerated the reaction, resulting in a higher exotherm, a higher peak temperature, and a higher monomer conversion within the range investigated. Shear strength, flexual strength, flexual modulus, and transverse tensile strength were proportional to monomer conversion. Flexual modulus increased with higher fiber content within the range observed. Data allow the proper combination of die temperature profile and pulling speed to be selected to achieve a desired level of monomer conversion and physical properties. Results of this study provide basic information required for product design with nylon-6 composites as well as tool design, selection of processing conditions, and quality control for the process.     

The development of a mathematical model for the pultrusion of blocked polyurethane composites

The thermokinetic behavior of blocked polyurethane-based composites during the pultrusion of glass-fiber reinforced composites is investigated utilizing a mathematical model accounting for the heat transfer and the heat generation during curing. The equations of continuity and energy balance, coupled with a kinetic expression for the curing system, are solved using a finite difference method to calculate the temperature and conversion profiles in the thickness direction in a rectangular pultrusion die. A kinetic model, dP/ dt = A exp(?E/RT) (1?P)ⁿP^m, was proposed to describe the curing behavior of a blocked polyurethane resin. Kinetic parameters for the model were obtained from dynamic differential scanning calorimetry (DSC) scans using a multiple regression technique, which was able to predict the effects of processing variables on the pultrusion. The effects of process variables (e.g., pulling rate, die temperature, and die thickness) on the performance of the pultrusion are also evaluated. © 1993 John Wiley & Sons, Inc.     

Development and characterization of high-performance polybenzoxazine composites

To develop high-performance composites with high temperature resistance, two newly synthesized polybenzoxazines were successfully cured with carbon fiber to obtain composites with 60 vol% fiber. Results from differential scanning calorimetry studies were used to modify the benzoxazine monomers to improve processability in terms of melting point and solubility. The density and void content of these composites were measured. Dynamic mechanical tests were performed to determine the glass transition temperature (T_g) and the activation enthalpy of the glass transition process for these two composites. The effect of cure temperature on the T_g of the composites was investigated. Thermal characteristics were studied by means of dynamic mechanical analysis in terms of isothermal aging, decomposition temperature from thermogravimetric analysis, and storage moduli change at high temperatures. Mechanical evaluations of these composites were conducted by flexural and interlaminar shear tests. The mechanical and thermal properties of these two composites exceed bismaleimide composites and compete with polyimide composites, while exhibiting easier processability than polyimides.     

Interpenetrating polymer networks of polyurethane and furfuryl alcohol,IIa. Processability and properties of pultruded fiber-reinforced composites

A feasibility study of pultrusion of fiber-reinforced polyurethane/furfuryl alcohol (PU/FA) interpenetrating polymer/network IPN composites has been made. From the viscosity study, it was found that the pot life of the PU/FA IPN prepolymers increased with PU content and showed high reactivity at elevated temperature. It was confirmed from the morphological study that the wetting of fibers by the PU/FA IPN resins was improved with PU content. The appearance of the tensile failure surfaces of the pultruded glass fiber-reinforced PU/FA IPN composites showed “hackle patterns” for PU contents below 15 phr. The mechanical property study shows that the tensile strength of pultruded PU/FA IPN composites is the highest when the PU content is 5 phr. However, the flexural strength, flexural modulus and HDT decreased with PU content. The mechanical properties of various fiber-reinforced (glass, carbon, and Kevlar 49 aramid fiber) pultruded PU/FA IPN composites increased with fiber volume content.     

Biobased chain extended polyurethane and its composites with silk fiber

The biobased chain extended polyurethane (PU) was synthesized by reacting castor oil based polyol with different diisocyanates [toluene‐2,4‐diisocyanate (TDI) and hexamethylene diisocyanate (HMDI)] and chain extender such as glutaric acid. Biocomposites have been fabricated by incorporating the silk fiber into both TDI‐ and HMDI‐based PUs. The effect of incorporation of silk fiber into TDI‐ and HMDI‐based neat PU on the physicomechanical properties such as density, surface hardness, tensile strength, and percentage elongation have been investigated. The dynamic mechanical properties and the thermal stability of neat PUs and the silk fiber incorporated PU composites have been evaluated. The TDI‐based neat PU has showed higher mechanical properties compared to HMDI‐based PU. The incorporation of 10% silk fiber into TDI‐ and HMDI‐based PU resulted in an enhancement of tensile strength by 1.8 and 2.2 folds, respectively. The incorporation of silk fiber into biobased chain extended PU increased the glass transition temperature (T_g) of the resultant biocomposites. The morphology of tensile fractured neat PUs and their biocomposites with silk fiber was studied using scanning electron microscope (SEM). POLYM. ENG. SCI., 2010. © 2009 Society of Plastics Engineers     

Mechanical properties of blocked polyurethane/epoxy interpenetrating polymer networks

The mechanical properties of blocked polyurethane(PU)/epoxy interpenetrating polymer networks (IPNs) were studied by means of their static and damping properties. The studies of static mechanical properties of IPNs are based on tensile properties, flexural properties, hardness, and impact method. Results show that the tensile strength, flexural strength, tensile modulus, flexural modulus, and hardness of IPNs decreased with increase in blocked PU content. The impact strength of IPNs increased with increase in blocked PU content. It shows that the tensile strength, flexural strength, tensile modulus, and flexural modulus of IPNs increased with filler (CaCO₃) content to a maximum value at 5, 10, 20, and 25 phr, respectively, and then decreased. The higher the filler content, the greater the hardness of IPNs and the lower the notched Izod impact strength of IPNs. The glass transition temperatures (T_g) of IPNs were shifted inwardly compared with those of blocked PU and epoxy, which indicated that the blocked PU/epoxy IPNs showed excellent compatibility. Meanwhile, the T_g was shifted to a higher temperature with increasing filler (CaCO₃) content. The dynamic storage modulus (E′) of IPNs increased with increase in epoxy and filler content. The higher the blocked PU content, the greater the swelling ratio of IPNs and the lower the density of IPNs. The higher the filler (CaCO₃) content, the greater the density of IPNs, and the lower the swelling ratio of IPNs. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1826–1832, 2006     

Dynamic mechanical properties of SBR and EPDM vulcanisates filled with cryogenically pulverized flexible polyurethane foam particles

The dynamic mechanical properties of rubber vulcanisates filled with cryogenically pulverized polyurethane foam particles, used as a reinforcing filler, were investigated with respect to storage modulus (E′), loss modulus, and the variation of glass transition temperature. Two rubbers were using styrene–butadiene rubber (SBR) and ethylene–propylene copolymer (EPDM). The effects of filler concentration and filler characteristics (such as particle size and moisture content) were also monitored. It was found that the optimum dynamic mechanical properties of the compounds were obtained when introducing the PU particles of 40–50 parts per hundred (pph) rubber in the SBR and 30 pph in the EPDM, the properties being affected by the size of PU particles and moisture content. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 1129–1139, 1999     

Swelling and static–dynamic mechanical behavior of mica-reinforced linear and star-branched polybutadiene composites

Physical properties of mica-reinforced linear (LPB) and star-branched polybutadiene (SPB) composites have been studied with special reference to the effect of silane coupling agent, degree of crosslinking, and degree of mica loading, as well as the molecular architecture of polybutadienes. Tensile properties increase and swelling decreases with addition of mica for linear polybutadiene. Star-branched polybutadiene shows a reverse behavior, especially beyond 5% of mica. The improvements in mechanical properties are more pronounced in the case of silane-treated mica compositions of both type of polybutadienes. Dynamic mechanical spectra were obtained for linear and star-branched polybutadienes. Effects of mica loading and silane treatment on dynamic moduli are discussed. Dynamic mechanical moduli (E′, E′) of composites increase with increasing mica content for linear polybutadiene but decrease for star-branched polybutadiene beyond certain mica loadings. Effective damping regions were determined in terms of frequency and temperature. The glass transition temperature (T_g) increased slightly, and the damping peak (tan δ) broadened due to the rubber—filler interaction, especially after silane treatment for both polymers. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 66: 1943–1952, 1997     

Pultruded fiber reinforced thermoplastic poly(methyl methacrylate) composites. Part II: Mechanical and thermal properties

A novel process has been developed to manufacture poly(methyl methacrylate) (PMMA) pultruded parts. The mechanical and dynamic mechanical properties, environmental effects, postformability of pultruded composites and properties of various fiber (glass, carbon and Kevlar 49 aramid fiber) reinforced PMMA composites have been studied. Results show that the mechanical and thermal properties (i.e. tensile strength, flexural strength and modulus, impact strength and HDT) increase with fiber content. Kevlar fiber/PMMA composites possess the highest impact strength and HDT, while carbon fiber/PMMA composites show the highest tensile strength, tensile and flexural modulus, and glass fiber/PMMA composites show the highest flexural strength. Experimental tensile strengths of all composites except carbon fiber/PMMA composites follow the rule of mixtures. The deviation of carbon fiber/PMMA composite is due to the fiber breakage during processing. Pultruded glass fiber reinforced PMMA composites exhibit good weather resistance. They can be postformed by thermoforming, and mechanical properties can be improved by postforming. The dynamic shear storage modulus (G′) of pultruded glass fiber reinforced PMMA composites increased with decreasing pulling rate, and G′ was higher than that of pultruded Nylon 6 and polyester composites.     

Simultaneous full‐interpenetrating polymer networks of blocked polyurethane and vinyl ester. II. Static and dynamic mechanical properties

Simultaneous full‐interpenetrating polymer networks (full‐IPNs) based on blocked polyurethane (PU) and vinyl ester (VE) have been prepared. The static and dynamic properties of these IPNs have been examined. Results show that the tensile strength and flexural strength of IPNs increased with blocked PU content to a maximum value at 7.5 wt % PU content and then decreased. The tensile modulus, flexural modulus, and hardness of IPNs decreased with increasing blocked PU content. The impact strength of IPNs increased with increasing blocked PU content. The tensile strength, flexural strength, tensile modulus, and flexural modulus of IPNs increased with filler (kaolin) content to a maximum value at 20 to 25 phr filler content and then decreased. The higher the filler content, the greater the hardness, and the lower the impact strength of IPNs. The tensile strength, flexural strength, tensile modulus, flexural modulus, and hardness of IPNs increased with increasing VE initiator content. The dynamic technique was used to determined the damping behavior across a temperature range. Results show that the glass transition temperature (T_g) of IPNs are shifted inwardly compared with pure PU and VE, which indicated that the blocked PU–VE IPNs showed excellent compatible. Meanwhile, the glass transition temperature was shifted to a higher temperature with increased filler content. The dynamic storage modulus (E′) of IPNs increased with increasing VE and filler content. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 1977–1985, 1999