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     

The unidirectional glass fiber reinforced furfuryl alcohol for pultrusion. I. Process feasibility and kinetic analysis

The development of unidirectional glass fiber reinforced furfuryl alcohol (FA) composites has been conducted using an in situ polymerization method. The FA prepolymer synthesized in this study was prepared from blends of FA monomer and catalyst (p‐toluene sulfonic acid). The process feasibility, and kinetic analysis of the unidirectional glass fiber reinforced FA composites by pultrusion has been investigated. From the investigations of the long pot life of FA prepolymer, the high reactivity of FA and FA/glass fiber, and excellent fiber wet‐out of FA resin and glass fiber, it was found that the FA resin showed excellent process feasibility for pultrusion. A kinetic autocatalytic model, dα/dt = A exp(−E/RT)α^m(1−α)ⁿ, was proposed to describe the curing behavior of FA/glass fiber composites. Kinetic parameters for the model were obtained from dynamic differential scanning calorimetry scans using a multiple regression technique. POLYM. COMPOS., 2008. © 2008 Society of Plastics Engineers     

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.     

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.     

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 blocked polyurethane (PU) composites. II. Processing variables and dynamic mechanical properties

Unidirectional fiber reinforced blocked polyurethane (PU) composites have been prepared by the pultrusion process. The effects of processing variables on the mechanical properties and dynamic mechanical properties of fiber reinforced PU composites by pultrusion have been studied. The processing variables investigated included pulling rate (in-line speed), die temperature, postcure time and temperature, and filler type and content. The dynamic mechanical properties of the composites produced by the process were studied utilizing dynamic mechanical spectrometer. Results show that the composites possessed various optimum pulling rates at different die temperatures. From the DSC data analysis, swelling ratio, and mechanical properties, the optimum die temperature was determined. It was found that the mechanical properties increase with filler content for various types of filler. The increasing of mechanical properties depends on the optimum postcure temperature and time. However, the properties decreased for longer postcure times since the composite materials were degraded. The glass-transition temperature (T_g) increased slightly and the damping peak (tan δ) was broadened due to fiber reinforcement. The dynamic mechanical moduli (G′, G″) of pultruded PU composites are apparently higher than those of the matrices. The moduli (G′, G″) increase with increasing fiber and filler content, and the damping peak becomes broad. Effect of postcuring on the degree of crosslinking, T_g, and dynamic modulus will be discussed.     

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     

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.     

碳纤维增强海因环氧树脂复合材料拉挤工艺性能研究

通过DSC分析及粘度和力学性能测试研究了海因环氧树脂/甲基六氢苯二酸酐/2-乙基-4-甲基咪唑体系的粘度特性,固化反应动力学,浇铸体及碳纤维增强拉挤成型复合材料的力学性能。结果表明,该体系在50℃下,15 h内粘度<500 mPa.s,可以满足拉挤工艺要求。其碳纤维复合材料的玻璃化温度达到206℃以上,剪切强度达到80 MPa,耐热性和力学性能良好。     

Effect of impregnation time on performance of long glass fiber‐reinforced polypropylene composites

Long glass fiber (LGF)‐reinforced polypropylene (PP) composites were prepared using self‐designed impregnation device. Effects of impregnation time on mechanical properties, crystallization, dynamic mechanical properties, and morphology of PP/LGF composites were investigated. The experiment results demonstrate that the excellent tensile strength, Notched Izod impact strength was 152.9 MPa, 31.2 KJ/m², respectively, and the stiffness of PP/LGF composites was higher, when the impregnation time was 7.03 s. The excellent interfacial adhesion between PP and glass fiber indicates that PP/LGF composites possess the outstanding mechanical properties. The impregnation time scarcely influenced thermal properties of PP/LGF composites. J. VINYL ADDIT. TECHNOL., 24:174–178, 2018. © 2016 Society of Plastics Engineers     

Fabrication of long glass fiber reinforced polyacetal composites: Mechanical performance,microstructures, and isothermal crystallization kinetics

A thermoplastic pultrusion was carried out to prepare the long fiber reinforced thermoplastic (LFT) composites based on polyacetal (POM) matrix on the custom‐designed pultrusion equipment. The investigation on mechanical performance revealed that the POM‐based LFT composites achieved much higher tensile, flexural, and impact strength than the short glass fiber reinforced ones at the same fiber loadings. Such a promising reinforcement effect is attributed to the feature that the residual fiber length in the injection‐molded LFT products is greatly superior to that in short fiber reinforced ones. This takes full advantage of the strength of the reinforcing fiber itself. The scanning electronic microscopy demonstrated that the fiber fracture and fiber pull‐out concurred on the tensile and impact fracture surfaces, and the former preceded the latter. The isothermal crystallization kinetics of the POM‐based LFT composites was also intensively studied, and the results indicated that the crystallinity of POM domain was enhanced by the heterogeneous nucleation of glass fiber, but the crystallization rate was postponed due to the interspace restriction toward crystalline growth caused by long glass fiber. These kinetic parameters provided information on the processing conditions of POM‐based LFT composites for the injection and compression molding. POLYM. COMPOS., 36:1826–1839, 2015. © 2014 Society of Plastics Engineers     

Replacement of styrene with acrylated epoxidized soybean oil in an unsaturated polyester resin from propylene glycol,isophthalic acid,and maleic anhydride

Commercial unsaturated polyester (UPE) resins typically contain a high amount of volatile toxic styrene. A non‐volatile acrylated epoxidized soybean oil (AESO) was found to be an excellent replacement of styrene in a commercially available UPE resin [designated as Styrene‐(PG‐IPA‐MA)] that is derived from propylene glycol (PG), isophthalic acid (IPA), and maleic anhydride (MA) in terms of the mechanical properties of the resulting kenaf fiber‐reinforced composites. The AESO‐(PG‐IPA‐MA) resins had low viscosity and long pot life below 70°C for a typical fiber‐reinforced composite application. AESO and PG‐IPA‐MA were not able to form a strong polymer matrix individually for fiber‐reinforced composites. However, a combination of AESO and PG‐IPA‐MA saw strong synergistic effects between them. The flexural, tensile, and water absorption properties of kenaf fiber‐reinforced composites made from AESO‐(PG‐IPA‐MA) resins were comparable with or even superior to those from the Styrene‐(PG‐IPA‐MA) resin. The AESO/(PG‐IPA‐MA) weight ratio was investigated for maximizing the mechanical properties of the kenaf fiber‐reinforced composites. The curing mechanism of the AESO‐(PG‐IPA‐MA) resins is discussed in detail. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43052.     

Effect of alkali‐resistant glass fiber on polypropylene/polystyrene blends: Modeling and characterization

Alkali‐resistant glass fiber (GF) reinforced polypropylene (PP)/polystyrene (PS) blends were prepared by melt mixing in a Thermo Haake Rheochord mixer. Variation in thermal and mechanical properties with the addition of glass fibers into the polypropylene/polystyrene blends was investigated. The characterization of PP/PS/GF composites was done by dynamic mechanical analysis (DMA), thermogravimetric analysis, scanning electron microscope, and transmission electron microscope. The experimentally observed tensile properties of glass fiber reinforced PP/PS blends were compared with various published models. It was found that the experimental results agree well with Hui‐ Shia and series models. DMA tests revealed an increase in storage modulus with fiber loading confirms the greater degree of stress transfer from the matrix to the fiber. TEM micrographs reveal that the glass fibers are located at the interface between the blend components. POLYM. COMPOS., 37:398–406, 2016. © 2014 Society of Plastics Engineers     

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     

Replacement of styrene with acrylated epoxidized soybean oil in an unsaturated polyester resin from propylene glycol and maleic anhydride

A nonvolatile, vegetable‐oil based chemical, acrylated epoxidized soybean oil (AESO) was investigated as a replacement of volatile and toxic styrene in one of commercial UPE resins styrene‐(PG‐MA) that is a mixture of styrene and a UPE plastic from propylene glycol and maleic anhydride (PG‐MA). Neither AESO nor PG‐MA was capable of forming a strong matrix, respectively, for glass fiber‐reinforced composites. However, a mixture of AESO and PG‐MA resulted in glass fiber‐reinforced AESO‐(PG‐MA) composites that were comparable or even superior to those from styrene‐(PG‐MA) in terms of the flexural and tensile properties. Effects of AESO contents on the mechanical and viscoelastic properties of the glass fiber‐reinforced AESO‐(PG‐MA) composites were investigated. Resin viscosity and resin pot life as a function of temperature were studied. The curing mechanism of the AESO‐(PG‐MA) resins is also discussed. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45056.     

LGF增强增韧PA66汽车专用料的制备及力学性能研究

采用熔融拉挤工艺技术制备了长玻璃纤维增强增韧尼龙(PA)66粒料.实验结果表明,长玻璃纤维增强增韧PA66具有拉伸强度大、弯曲强度大、冲击强度高、成型收缩率小等优异性能,其力学性能超过短玻璃纤维增强增韧PA66的性能,达到了汽车专用料标准要求.     

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.     

高低温老化对碳纤维复合材料芯棒结构性能的影响

采用拉挤工艺制备了碳纤维增强环氧树脂基复合材料芯棒,并对其进行高低温人工加速老化试验,以及对老化前后碳纤维复合材料芯棒的横截面、外观颜色和密度进行了测试和分析。结果表明,高低温老化使芯棒颜色加深,主要对芯棒的外层产生一定的影响,内部结构没有明显变化;老化后芯棒的密度比老化前减小约2.5%,并且不同老化周期对芯棒的密度基本不变。     

长玻璃纤维增强PP/m-PA6复合材料的制备及性能研究

采用熔融拉挤工艺技术制备了长玻璃纤维增强聚丙烯/聚酰胺6[LFT- (PP/m-PA6)]粒料,并研究了材料的界面相互作用情况、力学性能和流变性能。结果表明, m-PA6改善了PP树脂与玻纤之间的润湿性和浸淆性, 提高了界面粘接强度, 使LFT-(PP/m-PA6)的拉伸强度和弯曲强度增加、刚性增强、韧性基本不变; 当长玻纤含量相同时, 以均聚PP（F401）为基质的长玻纤增强聚丙烯（LFT-PP）和LFT-(PP/m-PA6)的力学性能高于以共聚PP（K712）为基质的LFT-PP和LFT-(PP/m-PA6),特别是缺口冲击强度明显提高;在-30 ℃下,LFT-PP（F401）的缺口冲击强度提高了3.91 %,LFT-PP（K712）的缺口冲击强度提高了7.53 %; m-PA6起到了界面润滑作用, 能使LFT-(PP/m-PA6)的流动性能更好。     

Mechanical properties of poly(styrene‐co‐acrylonitrile)‐modified epoxy resin/glass fiber composites

Poly(styrene‐co‐acylonitrile) was used to modify diglycedyl ether of bisphenol‐A type epoxy resin cured with diamino diphenyl sulfone and the modified epoxy resin was used as the matrix for fiber‐reinforced composites (FRPs) to get improved mechanical properties. E‐glass fiber was used as fiber reinforcement. The tensile, flexural, and impact properties of the blends and composites were investigated. The blends exhibited considerable improvement in mechanical properties. The scanning electron micrographs of the fractured surfaces of the blends and tensile fractured surfaces of the composites were also analyzed. The micrographs showed the influence of morphology on the properties of blends. Results showed that the mechanical properties of glass FRPs increased gradually upon fiber loading. Predictive models were applied using various equations to compare the mechanical data obtained theoretically and experimentally. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008