The effect of glycidyl methacrylate treatment of empty fruit bunch (EFB) on the properties of ultra‐violet radiation cured EFB‐unsaturated polyester composite

In this study, biofiber composites cured by ultra‐violet, were produced using pulp made from empty fruit bunch (EFB) as the reinforcing agent and unsaturated polyester as the matrix. The conversion of EFB fibers into pulp was carried out using organosolv pulping process. The EFB pulp was then chemically treated with glycidyl methacrylate (GMA) to different percentage of weight percent gain and the composites were made with different percentages of pulp loading. Results showed that the Kappa number of EFB decreased as the NaOH concentration in organosolv pulping increased. Composites which were made from GMA‐treated EFB showed better mechanical properties (tensile, flexural, and impact strength) than those of the unmodified. Fourier transform infrared spectroscopy showed peaks that proved the occurrence of grafting between GMA and OH from EFB pulp. Scanning electron microscope analysis showed the evidence of the enhancement of the compatibility between EFB and matrix. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Modification of unsaturated polyester resin with bismaleimide

The modification of a commercially available unsaturated polyester resin with 4,4′‐bismaleimidodiphenylmethane is presented. The properties of the modified resins were compared with those of the nonmodified resin, and the resins were characterized in the noncured state and after curing. The results indicate that the addition of bismaleimide to unsaturated polyester resin not only improves its properties but also accelerates the curing reactions. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 2003–2007, 2001     

Wettability and interfacial characterization of alkaline treated kenaf fiber‐unsaturated polyester composites fabricated by resin transfer molding

This paper reports on comprehensive characterization of wettability and interfacial properties of kenaf fibers (KF) and its unsaturated polyester (UPR) composites fabricated by resin transfer molding (RTM). KF were chemically modified by immersing in 6% NaOH concentration for 1, 2, 3, 4, and 5 h to enhance the interaction between KF and UPR. FTIR spectral data showed the chemical changes in KF after treatment which induced the modification of physical and wettability characteristics of KF. The changes in crystalinity index (CrI) and thermal stability of KF content were analyzed using X‐ray diffraction (XRD) and thermogravimetry (TGA) techniques, respectively. Scanning electron microscope (SEM) shows a cleaner KF surface upon KF treatment and atomic force microscopy (AFM) signify an increasing in available fiber–matrix specific contact area. Wettability of KF was investigated by means of surface energy measurement using Washburn contact angle principle via Owens–Wendt–Rabel–Kaelble (OWRK) method. Surface energy was found to increase with longer soaking time. The effect of soaking time of alkaline treatment in enhancing the interface bonding characteristic between the KF and UPR matrices can be reflected by the ILSS value of the composites. The highest value of ILSS was recorded by 3 h treated KF composite. POLYM. COMPOS., 38:507–515, 2017. © 2015 Society of Plastics Engineers     

Experimental characterization of woven jute‐fabric‐reinforced isothalic polyester composites

In this article, mechanical performance of isothalic polyester‐based untreated woven jute‐fabric composites subjected to various types of loading has been experimentally investigated. The laminates were prepared by hand lay‐up technique in a mold. Specimens for tests were fabricated as per ASTM standards. All the tests (except impact) were conducted on closed loop servo hydraulic MTS 810 material test system using data acquisition software Test Works‐II. From the results obtained, it was found that the tensile strength and tensile modulus of jute‐fabric composite are 83.96% and 118.97% greater than the tensile strength and modulus of unreinforced resin, respectively. The results of other properties, such as flexural, in‐plane shear, interlaminar shear, impact, etc., also revealed that the isothalic‐polyester‐based jute‐fabric composite have good mechanical properties and can be a potential material for use in medium load‐bearing applications. The failure mechanism and fiber‐matrix adhesion were analyzed by scanning electron microscope. Effects of long‐term immersion in water on mechanical properties are also presented. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 2650–2662, 2007     

桐油改性双环戊二烯不饱和树脂的合成研究

利用缩聚反应后期桐油与双环戊二烯不饱和聚酯(DCPD-UPR)主链上不饱和双键的Diels-Alder(D-A)反应合成了桐油改性DCPD-UPR,研究了各种原料用量对桐油改性DCPD-UPR其浇注体力学性能的影响。结果表明:当顺酐与苯酐的物质的量比为2∶1～3∶1,双环戊二烯与顺酐物质的量比为0.6～0.8∶1,1,2-丙二醇与二甘醇物质的量比2∶1,缩聚反应后期加入10%(质量分数)桐油,苯乙烯质量分数为35%～40%时,获得的桐油改性DCPD-UPR粘度适中,浇注体的断裂伸长率提高了78.2%,冲击强度提高了82.0%。     

Hemp‐fiber‐reinforced unsaturated polyester composites: Optimization of processing and improvement of interfacial adhesion

The processing variables for making hemp‐fiber‐reinforced unsaturated polyester (UPE) composites were optimized through orthogonal experiments. It was found that the usage of initiator, methyl ethyl ketone peroxide, had the most significant effect on the tensile strength of the composites. The treatment of hemp fibers with a combination of 1,6‐diisocyanatohexane (DIH) and 2‐hydroxyethyl acrylate (HEA) significantly increased tensile strength, flexural modulus of rupture, and flexural modulus of elasticity, and water resistance of the resulting hemp‐UPE composites. FTIR spectra revealed that DIH and HEA were covalently bonded to hemp fibers. Scanning electron microscopy graphs of the fractured hemp‐UPE composites demonstrated that treatment of hemp fibers with a combination of DIH and HEA greatly improved the interfacial adhesion between hemp fibers and UPE. The mechanism of improving the interfacial adhesion is proposed. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

2010-2011年国际不饱和聚酯树脂工业进展

介绍了2010-2011年国际原油市场、不饱和聚酯部分项目投产及企业并购情况。综述了UPR领域的研究及应用进展,包括UPR的改性、力学性能的改进、老化机理、生物复合材料、新型不饱和聚酯复合材料及其应用。     

Curing of styrene‐free unsaturated polyester alkyd: synthesis,characterization and simulation

Experimental and simulation studies of the crosslinking process of styrene‐free unsaturated polyester (UP) alkyd chains are presented. The thermal and mechanical properties of the crosslinked UP alkyd are studied as a function of the peroxide concentration. The characterized and simulated thermoset matrix properties are compared. Simulation of the crosslinking reaction is used to improve the understanding of the process and to define the species involved in it. The main experimental characterization tools used were differential scanning calorimetry and dynamic mechanical analysis. The main simulation tools used were a Monte Carlo procedure for the crosslinking process and a density functional theory‐based quantum code for the scission process. Good agreement between the experimental and simulation results was achieved. Copyright © 2010 Society of Chemical Industry     

N-苯马来酰亚胺改性不饱和聚酯树脂

研究了N-苯基马来酰亚胺(NPMI)在苯乙烯中的溶解规律,即NPMI在苯乙烯中溶解度呈线性关系:5~35℃时,S=0.1t;40~60℃时,S=4.2+2.2t。NPMI的引入可以有效提高不饱和聚酯(UP)树脂的耐热性,NPMI用量在1%~9%,可以将UP树脂的热变形温度提高4.5℃。研究了NPMI用量对UP树脂浇注体拉伸强度和冲击强度的影响,对材料冲击断面进行了SEM表征。NPMI用量为2%时,材料的拉伸强度最大,提高了5.5%,达到67.3 MPa;NPMI用量为6%时,材料的冲击强度最大,提高了23%,达到8.6 kJ/m2。     

豆油制备不饱和聚酯树脂性能研究

以可再生资源豆油、丙三醇为原料醇解制备了单甘酯,将其作为二元醇,部分取代丙二醇与酸酐反应制得不饱和聚酯树脂(UP)。采用DSC,DMA以及力学性能测试等手段研究了单甘酯含量对豆油不饱和聚酯树脂性能的影响。结果表明,随着单甘酯含量的增加,豆油不饱和聚酯树脂的固化放热峰值降低、固化收缩率减小;存储模量和玻璃化转变温度都有一定程度降低,弯曲强度和拉伸强度也逐渐下降;冲击强度和拉伸断裂伸长率增高(单甘酯质量分数为40%时可分别达到102.074 kJ/m2和27.69%)。该方法制备的UP树脂成本低廉,柔韧性好,可满足一般的使用要求。     

不饱和聚酯树脂产品质量存在的问题及其建议

概述了不饱和聚酯树脂的分类及应用;提出了国内不饱和聚酯树脂产品质量存在的问题及其建议.     

支化结构不饱和聚酯的合成及性能研究

以乙二醇、季戊四醇(丙三醇)、反丁烯二酸为原料合成了含支化结构的不饱和聚酯(RP),对产物进行了红外表征,并通过GPC、DSC和TGA测试对其性能进行了研究。结果表明,季戊四醇(丙三醇)用量为反丁烯二酸物质的量的5%为宜,最佳反应温度为190～200℃,RP树脂数均分子质量为线形UP树脂的5倍左右。RP树脂相比UP树脂固化快,其最大放热温度、热稳定性和冲击性能均有所提高,其中冲击强度提高33%。此外,丙三醇型RP树脂较季戊四醇型反应易于控制,反应程度高。     

Epoxidized phenolic novolac: A novel modifier for unsaturated polyester resin

Unsaturated polyester resins (UPRs) are used widely in the fiber‐reinforced plastics (FRPs) industry. These resins have the disadvantages of brittleness and poor resistance to crack propagation. In this study, hybrid polymer networks (HPNs) based on UPR and epoxidized phenolic novolacs (EPNs) were prepared by reactive blending. A HPN is composed of a backbone polymer containing two types of reactive groups that can take part in crosslinking reactions via different mechanisms. EPNs were prepared by glycidylation of novolacs using epichlorohydrin. The novolacs had varying phenol: formaldehyde ratios. Blends of unsaturated polyester with EPN were then prepared. The physical properties of the cured blends were compared with those of the control resin. EPN shows good miscibility and compatibility with the resin and improves the toughness and impact resistance substantially. Considerable enhancement of tensile strength is also noticed at about 5% by weight of epoxidized novolac resin. TGA, DMA, and DSC were used to study the thermal properties of the toughened resin and the fracture behavior was studied using SEM. The blends are also found to have better thermal stability. Blending with EPN can be a useful and cost‐effective technique for modification of UPR. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 457–465, 2006     

Flame‐retardant,glass‐fabric‐reinforced epoxy resin laminates fabricated through a gradient distribution mode

In general, epoxy resin (EP) glue mixed with a high content of flame retardants is used to coat glass fabrics layer by layer to prepare fire‐retardant printed circuit boards (PCBs). However, the addition of the flame retardants not only increases the cost but also greatly deteriorates the processability and mechanical properties of the PCBs. In this study, a gradient distribution mode of composite flame retardants was designed and applied in EP‐based PCB composites. Unlike the traditional uniform distribution mode, in which flame retardants are evenly distributed in every resin layer, the gradient mode concentrates a higher content of the flame retardants on the surface layer, and the concentrations are gradually reduced along the thickness. In this way, the surface resin can quickly form a condensed charring barrier to hold back fire; this effectively protects the underlying resin, which has lower contents of flame retardant. The results of this study show that PCB prepared by the gradient mode obtained satisfactory flame retardance (a UL94 V‐0 rating) with only a 3.5 wt % total amount of flame retardant; this value was much lower than that (6.3 wt %) of composites featuring a uniform distribution. Additionally, the gradient mode also maintained the mechanical properties of PCB better. The tensile, impact, and flexural strengths of the gradient distribution system were obviously higher than those of the uniform distribution one with the same content of flame retardant. On the basis of the mode, a more economic and efficient technology was developed to manufacture flame‐retardant layered PCB. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44369.     

2步法合成双环戊二烯型不饱和聚酯树脂

采用2步法合成了原子灰用双环戊二烯(DCPD)型不饱和聚酯树脂,研究了原料用量对树脂性能影响,当n(顺酐)∶n(工业DCPD)∶n(精制DCPD)∶n(二元醇)=2.0∶0.7∶0.5∶1.75时,树脂性能稳定,原子灰综合性能如气干性、耐热性、打磨性、刮涂性、柔韧性等良好。     

The role of additives in the manufacture of sheets of unsaturated polyester and postconsumer unsaturated polyester/glass fiber composites: Mechanical and dynamic mechanical properties

The storage of postconsumer glass fiber reinforced unsaturated polyester composite impacts negatively on the environment because of the long lifetime and the volume/amount ratio of residuals, which are important aspects to be considered. Two types of additives were employed as an attempt to improve the mechanical properties of sheets manufactured with ground postconsumer glass fiber reinforced orthophthalic unsaturated polyester resin composite and virgin orthophthalic unsaturated polyester resin, a silane‐coupling agent and an organic dispersant. Flexural and impact tests, and dynamic mechanical analyses, demonstrated that the coupling agent increased the mechanical properties, while the dispersant decreased these properties, compared to material without either additive. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1834–1839, 2004     

Modification of unsaturated polyester resin by polyurethane prepolymers

Unsaturated polyester resins (UPRs) are extensively used by the fiber‐reinforced plastic (FRPs) industry. These resins have the disadvantages of brittleness and poor resistance to crack propagation. In this study, UPRs were chemically modified by reactive blending with polyurethane prepolymers having terminal isocyanate groups. Hybrid networks were formed by copolymerisation of unsaturated polyesters with styrene and simultaneous reaction between terminal hydroxyl groups of unsaturated polyester and isocyanate groups of polyurethane prepolymer. The prepolymers were based on toluene diisocyanate (TDI) and each of hydroxy‐terminated natural rubber (HTNR), hydroxy‐terminated polybutadiene (HTPB), polyethylene glycol (PEG), and castor oil. Properties like tensile strength, toughness, impact resistance, and elongation‐at‐break of the modified UPRs show considerable improvement by this modification. The thermal stability of the copolymer is also marginally better. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 449–456, 2006     

Investigation of unsaturated polyester composites reinforced by aspen high‐yield pulp fibers

Aspen chemithermomechanical pulp fiber‐reinforced unsaturated polyester (UPE) composites were fabricated using premade paper handsheets. The effects of handsheet wet‐pressing pressure, grammage, and subsequent fabrication methods on the composite properties were evaluated. The composites obtained using the optimum process parameters had tensile moduli and tensile strengths comparable with those of traditional glass fiber‐reinforced UPE composites. The pressed composites had very consistent tensile moduli that were well fitted by the Halpin–Tsai and Tsai–Pagano models. The classical Kelly‐Tyson and Bowyer‐Bader models significantly underestimated the composite tensile strengths and the potential reasons for this discrepancy are discussed. POLYM. COMPOS., 2012. © 2011 Society of Plastics Engineers     

Cure characterization of unsaturated polyester resin by fluorescence spectroscopy

A strong fluorescence emission was observed during cure of an unsaturated polyester resin containing about 30% styrene by weight. As the cure proceeded, the emission intensity at 306 nm increased. Model compound studies confirmed that the unsaturated polyester component exhibited negligible fluorescence when excited at 250 nm where styrene has strong absorption. Based on the studies of styrene/polystyrene mixtures, the fluorescence emission at 306 nm was attributed to a reduced inner‐filter effect of styrene monomer. Fluorescence intensity changes following cure at 75°C were correlated to the extent of styrene conversion determined by FT‐IR spectroscopy, demonstrating that the fluorescence measurement is more sensitive to styrene conversion in the later stages of cure than conventional IR measurements. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 2446–2450, 2004     

超支化聚酯改性聚酯亚胺不饱和树脂

合成了一种带柔性链的芳醚型聚酯亚胺不饱和树脂(AEPUR),采用红外光谱技术对其结构进行了表征。研究了端羧基超支化聚酯(HTM-4)对AEPUR/环氧树脂E-44共混体系的弯曲性能、冲击性能和热性能的影响。结果表明,HTM-4能显著提高AEPUR/E44共混物的冲击强度和弯曲性能,表现出明显的增韧/增强作用,体系的热分解温度变化不大,残碳率明显增加。