Chemical modification of unsaturated polyesters influence of polyester's structure on thermal and viscoelastic properties of low styrene content copolymers

In this study, the chemical modification of unsaturated polyesters and the influence of polyester's structure on thermal and viscoelastic properties have been presented. The structure of unsaturated polyesters obtained in polycondensation of cyclohex‐4‐ene‐1,2‐dicarboxylic anhydride (THPA), maleic anhydride and only one suitable symmetrical glycol: ethylene glycol or 1,4‐butanediol (BDO) or 1,6‐hexanediol has been modified by peracetic acid. The selective oxidation of unsaturated polyesters conducted in mild time and temperature conditions was a successful and effective method to prepare new materials/unsaturated epoxy polyesters/containing epoxy groups in cycloaliphatic rings and carbon–carbon double bonds in polyester chain. The unsaturated epoxy polyesters were capable of both copolymerization with vinyl monomer and polyaddition reactions with suitable curing agent. Therefore, they were successfully used as a component of low styrene content copolymers. As was confirmed by DSC, DMA, and TGA analyses, polyester's structure had significant influence on thermal and viscoelastic properties of styrene copolymers. The properties of styrene copolymers prepared from unsaturated epoxy polyesters were considerably better compared with those obtained for styrene copolymers from unsaturated polyesters.© 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Synthesis and characterization of the new unsaturated epoxyoligoester suitable for further modification

In this article, the synthesis and characterization of the new unsaturated epoxyoligoester suitable for further modification have been presented. The new unsaturated epoxyoligoester was prepared by the chemical modification of the structure of the unsaturated oligoester obtained in polycondensation process of cyclohex‐4‐ene‐1,2‐dicarboxylic anhydride, maleic anhydride, and ethylene glycol. The chemical modification of the structure of initial oligoester by 38–40% peracetic acid in mild conditions allowed to introduce the oxirane groups into the oligoester backbone. The structure of the samples before and after epoxidation was characterized by FTIR, ¹H NMR, DSC, and elemental analyses. The FTIR and ¹H NMR analyses confirmed that the oxidation reaction took place through the double bonds in cyclohexenyl rings, whereas the double bonds in the unsaturated chain remained unaltered. Moreover, the epoxidation reaction was performed at 20 and 40°C for 1–6 h to define the optimum temperature and time conditions of this process. The optimum temperature and time conditions were 40°C and 2.5 h, respectively. In this conditions, the maximum conversion of the double bonds (98.3%) and minimal epoxide degradation were observed. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Curable resins based on recycled poly(ethylene terephthalate) for coating applications

Poly(ethylene terephthalate) waste was depolymerised in the presence of diethylene- or tetraethylene glycol and manganese acetate as a catalyst. An epoxy resin was then prepared by the reaction of these oligomers with epichlorohydrin in presence of NaOH as a catalyst. The produced oligomers were condensed with maleic anhydride and ethylene glycol to produce unsaturated polyester. The chemical structures of the resulting epoxy and unsaturated polyester resins were confirmed by ¹HNMR. The vinyl ester resins were used as cross-linking agents for unsaturated polyester resin diluted with styrene, using free radical initiator and accelerator. The 2-amino ethyl piprazine was used as hardener for epoxy resins. The curing behaviour of the unsaturated polyester resin, vinyl ester resins and styrene was evaluated at different temperatures ranged from 25 to 55 °C to calculate the curing activation energy of the system. The cured epoxy and unsaturated polyester resins were evaluated in coating application of steel.     

New aspects of unsaturated polyester resin synthesis. Part 2. Reactant sequence distribution and its effect on cure kinetics

The distribution of unsaturations in the prepolymer of a typical unsaturated polyester (UP) resin (maleic anhydride, phthalic anhydride and 1,2‐propylene glycol) has been shown to influence the kinetics of the cure process with styrene monomer. Segments containing double bonds in close proximity appear to lower the reactivity of the resin due to steric hindrance, as indicated by the fact that the rate of cure and the final degree of cure, measured by differential scanning calorimetry (DSC), increase as the average sequence length (SL) of maleic units decreases. This implies that the reactivity of UP resins may be improved by synthesis of prepolymers with certain reactant sequence‐length distributions. The copolymer formed by the melt condensation process of maleic anhydride, phthalic anhydride and 1,2‐propylene glycol in the absence of a transesterification catalyst has a non‐random structure with a tendency towards blockiness. This was established using ¹H NMR analysis in tandem with deterministic and Monte Carlo modelling techniques. Copyright © 2003 Society of Chemical Industry     

Rice husk–polyester composites: The effect of chemical modification of rice husk on the mechanical and dimensional stability properties

Rice husk was used as filler in the production of rice husk (RH)–polyester composites and was subjected to three types of chemical modification. The chemical reagents employed in this study were glycidyl methacrylate (GMA), maleic anhydride (MAH), and succinic anhydride (SAH). This study revealed that the chemical modification of RH with GMA and MAH resulted in the enhancements of tensile and flexural properties of RH–polyester composites. The reduction in these properties with respect to those modified with SAH were attributed to the absence of C?C unsaturated groups. Water immersion test showed that chemical modification of the RH improved the dimensional stability of the composites. This was shown in the GMA‐ and MAH‐modified RH–polyester composites. The modification increased the hydrophobicity as well as the crosslinking between the RH and matrix in the composites. The lower performance demonstrated by the SAH‐modified composites was due to the inability of the SAH to form crosslinking with the matrix. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 1237–1247, 2005     

Synthesis and characterization of excellent transparency poly(urethane‐methacrylate)

A series of novel crosslinked poly(urethane–methacrylate) (PUA) was synthesized. PUA was polymerized in a three‐step process: The low number average molecular weight unsaturated polyester (UPE) containing hydroxyl groups was synthesized by 1,2‐propanediol (PG), 2‐butyl‐2‐ethyl‐1,3‐propanediol (BEPD) and maleic anhydride (MA). A series of prepolymers, which had double bonds at the end of the chain, was prepared from isophorone diisocyanate (IPDI), UPE, and β‐hydroxyethyl methacrylate (HEMA) in the presence of dibutytin dilaurate (DBTL) as catalyst. The novel functional prepolymer was initiated by 2,2‐azobis‐isobutyronitrile(AIBN) to form thermosetting materials. The structure of the thermosetting materials was characterized by Fourier Transform Infrared (FTIR). Mechanical, thermal, and optical properties were tested. The results showed that the advanced PUA had good thermal and mechanical properties and high transparence. The throughput of PUA was above 90%, thus the PUA was possible to be used as excellent optical material. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Synthesis and thermal stability of a novel cycloaliphatic epoxy resin system

A novel cycloaliphatic epoxy resin was synthesized from dicyclopentadiene, ethylene glycol, and nadic anhydride. The chemical structures of the resultant epoxy resin and its precursor were characterized with Fourier transform infrared spectroscopy, ¹H‐NMR, and mass spectrographic analyses. The thermal stability of the cured polymer was investigated with differential scanning calorimetry and thermogravimetric analysis. Compared with the thermal stability of the commercial cycloaliphatic epoxy resin 3,4‐epoxy cyclohexyl methyl‐3′,4′‐epoxy cyclohexyl carboxylate, a higher thermal stability for the cured polymer of the novel epoxy resin was observed. The results imply that the novel cycloaliphatic epoxy resin has good potential applications in electronic encapsulation. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

双环戊二烯研究新进展

双环戊二烯主要来自石油裂解制乙烯副产物的C5馏分和煤炭焦化副产物.由于双环戊二烯分子结构中同时含有两个不饱和双键,致使其化学性质非常活泼,可与多种化合物反应,生成种类繁多的衍生物,这些衍生物用途非常广泛,因此双环戊二烯及其衍生物产品的研究开发具有广阔的市场应用前景.综述了双环戊二烯的结构、性能、生产及其在高分子材料和精细有机化工领域中国内外研究的最新进展,重点论述了双环戊二烯在不饱和聚酯树脂、双环戊二烯-酚型树脂、聚双环戊二烯材料、环氧树脂、光学有机玻璃材料以及金属有机化合物、农药、香料、金刚烷等产品的合成中的应用.     

Effects of chemical structure of polyurethane‐based low‐profile additives on the miscibility,curing behavior,volume shrinkage,glass transition temperatures,and mechanical properties for styrene/unsaturated polyester/low‐profile additive ternary systems. II: Glass transition temperatures and mechanical properties

The effects of three series of thermoplastic polyurethane‐based (PU) low‐profile additives (LPA) with different chemical structures and molecular weights on the glass transition temperatures and mechanical properties for thermoset polymer blends made from styrene (ST), unsaturated polyester (UP), and LPA have been investigated by an integrated approach of static phase characteristics‐cured sample morphology‐reaction conversion‐property measurements. The three series of PU used were made from 2,4‐tolylene di‐isocyanate (2,4‐TDI) and varied diols, namely polycaprolactone diol (PCL), poly(diethylene adipate) diol (PDEA), and poly(propylene glycol) diol (PPG), respectively, while the two UP resins employed were synthesized from maleic anhydride (MA) and 1,2‐propylene glycol (PG) with and without modification by phthalic anhydride (PA). Based on the Takayanagi mechanical models, factors that control the glass transition temperature in each phase region of cured samples, as identified by the method of thermally stimulated currents (TSC), and mechanical properties will be discussed. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 558–568, 2000     

Network structure/mechanical property relationship in multimethacrylates—Derivatives of nadic anhydride

In this article the syntheses of dimethacrylate and trimethacrylate esters as well as the mechanical and thermal properties of their copolymers with methyl methacrylate and styrene are investigated. The esters were obtained from acidic derivatives of nadic anhydride and glycidyl methacrylate. The addition reaction of glycidyl methacrylate and the acidic compound was carried out in the presence of basic catalyst—tetraethylammonium bromide. The monomers and resins were UV cured in the presence of a suitable photoinitiator which was 2,2‐dimethoxy‐2‐phenyloacetophenone. The prepared polymers were subjected to different studies concerning evaluation of their mechanical properties, thermal stability, dynamic mechanical behavior (DMA) as well as the estimation of the content of unreacted double bonds in the final product. The results proved their good thermal and mechanical properties. The degree of unsaturated bonds conversion was found to be growing with the amount of monovinyl monomer in the copolymer. Trimethacrylate‐based copolymers are characterized by a greater content of double bonds present in the obtained material compared to that of dimethacrylate‐based copolymers. As indicated by DMA the network structures of the copolymers seem to be more heterogeneous with the increasing weight fraction of trimethacrylate as well as dimethacrylate monomer. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Water uptake,chemical characterization,and tensile behavior of modified banana–plantain fiber and their polyester composites

Banana–plantain fibers (BPFs) were treated with acetic anhydride (AA), epichlorohydrin (EP), and an acetic anhydride–epichlorohydrin blend (AA_EP). Natural fiber–polyester composites (PCs) were fabricated using untreated and treated BPF by the hand lay‐up technique. Modified BPF Raman and Infrared spectroscopy (ATR‐FTIR) analysis revealed losses of lignin and hemicelluloses and new chemical bonds that confirmed the replacement of part of the raw fiber hydroxyl groups, which gave rise to a degree of hydrophobicity in the treated fibers. This change altered their water sorption isotherms, swelling behavior in water, impedance spectroscopy, and XRD analysis. Assays of water absorption and tensile resistance for untreated BPF (U) and modified BPF polyester composites demonstrated a remarkable reduction in water intake, whereas tensile strength was maintained (P < 0.05) for the modified BPF polyester composites. POLYM. COMPOS., 37:2960–2973, 2016. © 2015 Society of Plastics Engineers     

由苧烯合成脂环族双环氧化合物及固化物热性能

以天然产物(R)-(+)-苧烯为原料,通过烯烃加氢烷基化、酯化和有机过氧化物环氧化反应合成得到含有苧烯结构单元的新型双官能团脂环族环氧化合物。利用核磁共振波谱(1HNMR和13CNMR)、质谱和红外光谱(FTIR)来表征反应中间体和脂环族环氧化合物结构。以2-乙基-4-甲基咪唑为促进剂、酸酐为固化剂,采用示差扫描量热(DSC)和热重分析(TGA)方法研究该脂环族环氧固化物的热性能。环氧化合物与甲基六氢邻苯二甲酸酐、4-环己烯-1,2-二甲酸酐和内亚甲基邻苯二甲酸酐固化产物的Tg分别为158、137、150℃。结果表明,脂环族环氧化合物与酸酐固化剂热固化后得到的交联聚合物具有良好的热性能。     

Effect of glycol and filler types on some polymeric composite properties

Two unsaturated polyesters based on maleic anhydride, phthalic anhydride, and sebasic acid with each of linear 1,6‐hexanediol (PE_L) and cyclic 1,4‐cyclohexanediol (PE_C) were prepared. Their structures were characterized by IR and ¹H NMR spectra. Their composites were prepared by mixing different ratios (60, 70, and 80%) with talc and kaolin with polyester/styrene mixture. The effect of linear and cyclic glycols and the effect of filler type and concentration of these composites were studied in terms of their electrical properties and the hardness before and after aging. The thermal behavior of styrenated polyesters and their composites was studied using thermogravimetric analysis. It has been found that both fillers increase the thermal stability and decrease the weight loss. The permittivity ε′ and the dielectric loss ε″ were measured in the frequency range 100 Hz up to 100 kHz at room temperature 25°C ± 1. The polyester composite samples containing 70% filler lead to good electrical properties in addition to its resistance to thermal aging. The hardness value was increased by increasing the filler content before and after aging. The polyester composites based on cyclic glycol and loaded with 80% kaolin gave the highest hardness values. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

UV-curing behavior of unsaturated cyclohexanone formaldehyde resins with thiols

Numerous researches about the modification and application of cyclohexanone formaldehyde resins (CFR) have been conducted, few of them involve in the UV-curing of unsaturated CFR with thiols. Thus, CFR are synthesized using the rehydrated magnesium-aluminum hydrotalcite as the catalyst and double bonds are introduced by capping the chain ends with 5-norbornene-2,3-dicarboxylic anhydride. Through monitoring the conversion of double bonds with FTIR, the UV-curing behavior of unsaturated CFR in the presence of pentaerythritol tetra (3-mercaptopropionate) is studied. The results show that the conversion of double bonds can reach to 64.1% at 0.66 mW cm⁻² of UV light intensity when the molar ratio of double bonds to sulfhydryl groups is 1:1 in the presence of benzoin dimethyl ether (1% of molar amount of double bonds). Considering the similarity between UV-curing of thiols-double bonds and thermo-curing of amine-epoxy, one diffusion controlled kinetics model is derived and it shows good fitness. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48420.     

端羧基超支化聚酯改性环氧树脂固化体系研究

利用丁二酸酐对端羟基超支化聚酯(AHBP)的端基进行改性,得到新的端羧基超支化聚酯(CHBP),并将其用于环氧树脂体系的增韧。研究了CHBP用量、羧基含量对环氧树脂/甲基四氢苯酐(EP/MeTHPA)固化体系的力学性能和热性能的影响。结果表明,改性后分子末端全部带羧基的CHBP的增韧作用最好,冲击强度可达18.5kJ/m2。CHBP质量分数为15%时,固化物的冲击强度可达18.2 kJ/m2,拉伸强度64.86 MPa,玻璃化温度(Tg)从100℃提高到106℃左右,可满足增韧环氧树脂的同时不降低其耐热性的要求。     

马来酸酐改性超支化聚酯及在紫外光固化涂层中的应用

以马来酸酐改性末端为羟基的超支化聚酯,得到链段中含大量不饱和双键的超支化马来酸酯,分析表征了不同改性度的超支化马来酸酯黏度、热稳定性及Tg的变化。以超支化马来酸酯为预聚物应用于紫外光固化涂层,考察了改性度对光固化膜附着力、冲击强度、柔韧性、硬度及耐溶剂性能的影响。实验表明,超支化马来酸酯是一种低黏度、热稳定性好、Tg易调节的高分子材料。当改性度为80%时,光固化涂层性能最佳,其光固化时间可达3 s,膜附着力为1级,耐冲击强度为4.8 N.m,柔韧性>7 cm,硬度达5H,同时具有优良的耐溶剂性能。     

Synthesis and application of water‐based urethane acrylate crosslinking agent containing unsaturated group

In this study, we synthesized 1,1,1‐trimethlyolpropane (TMP)‐based diol which has a pendant anionic group and a reactive double bond in the pendant cyclic ring. Then, a water‐based urethane acrylate crosslinking agent (CA) was prepared from isophrone diisocyanate (IPDI), 2‐hydroxyethyl acrylate (2‐HEA), and a low molecular weight diol bearing pendant carboxylic acid. The CA content was varied in order to investigate the influence of the added content on the mechanical and dynamic mechanical properties. The diol used in this study was TMP–cis‐1,2,3,6‐tetrahydrophthalic anhydride (TPA) which was synthesized from the esterification reaction of TMP with TPA. This diol was liquid at room temperature. As the CA increased, the initial modulus and elongation at break decreased. Also, increase of the rubbery plateau modulus was observed by dynamic mechanical analysis (DMA). This result was believed to result from an increase in the crosslinking density in the mixtures. Shift of the T_gh to a higher temperature was also observed by DMA. This is due to the increased hard segments and the phase separation. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 1216–1223, 2000     

Thermo mechanical behaviour of unsaturated polyester toughened epoxy–clay hybrid nanocomposites

The intercrosslinked networks of unsaturated polyester (UP) toughened epoxy–clay hybrid nanocomposites have been developed. Epoxy resin (DGEBA) was toughened with 5, 10 and 15% (by wt) of unsaturated polyester using benzoyl peroxide as radical initiator and 4,4′-diaminodiphenylmethane as a curing agent at appropriate conditions. The chemical reaction of unsaturated polyester with the epoxy resin was carried out thermally in presence of benzoyl peroxide-radical initiator and the resulting product was analyzed by FT-IR spectra. Epoxy and unsaturated polyester toughened epoxy systems were further modified with 1, 3 and 5% (by wt) of organophilic montmorillonite (MMT) clay. Clay filled hybrid UP-epoxy matrices, developed in the form of castings were characterized for their thermal and mechanical properties. Thermal behaviour of the matrices was characterized by differential scanning calorimetry (DSC), thermo gravimetric analysis (TGA) and dynamic mechanical analysis (DMA). Mechanical properties were studied as per ASTM standards. Data resulted from mechanical and thermal studies indicated that the introduction of unsaturated polyester into epoxy resin improved the thermal stability and impact strength to an appreciable extent. The impact strength of 3% clay filled epoxy system was increased by 19.2% compared to that of unmodified epoxy resin system. However, the introduction of both UP and organophilic MMT clay into epoxy resin enhanced the values of mechanical properties and thermal stability according to their percentage content. The impact strength of 3% clay filled 10% UP toughened epoxy system was increased by 26.3% compared to that of unmodified epoxy system. The intercalated nanocomposites exhibited higher dynamic modulus (from 3,072 to 3,820 MPa) than unmodified epoxy resin. From the X-ray diffraction (XRD) analysis, it was observed that the presence of d ₀₀₁ reflections of the organophilic MMT clay in the cured product indicated the development of intercalated clay structure which in turn confirmed the formation of intercalated nanocomposites. The homogeneous morphologies of the UP toughened epoxy and UP toughened epoxy–clay hybrid systems were ascertained from scanning electron microscope (SEM).     

Synthesis and antitumour and antiangiogenesis activity of polymers containing methacryloyl‐2‐oxy‐1,2,3‐propane tricarboxylic acid

A new monomer, methacryloyl‐2‐oxy‐1,2,3‐propane tricarboxylic acid (MTCA), was synthesized from citric acid and methacrylic anhydride. Poly(methacryloyl‐2‐oxy‐1,2,3‐propane tricarboxylic acid) and poly(methacryloyl‐2‐oxy‐1,2,3‐propane tricarboxylic acid)‐co‐(maleic anhydride) were prepared by radical polymerizations. Terpoly(methacryloyl‐2‐oxy‐1,2,3‐propane tricarboxylic acid–maleic anhydride–furan) was obtained by in situ terpolymerization of MTCA and exo‐3,6‐epoxy‐1,2,3,6‐tetrahydrophthalic anhydride. The synthesized samples were identified by FTIR, ¹H NMR and ¹³C NMR spectroscopies. The number‐average molecular weights of the fractionated polymers determined by GPC were in the range 14 900–16 600 and polydispersity indices were less than 1.14. The in vitro IC₅₀ values of the monomer and polymers against cancer and normal cell lines were much higher than those of 5‐fluorouracil (5‐FU). The in vivo antitumour activities of the synthesized samples at a dosage of 0.8 mg kg⁻¹ against mice bearing the sarcoma 180 tumour cell line decreased in the order terpoly(MTCA‐MAH‐FUR) > poly(MTCA‐co‐MAH) > poly(MTCA) > MTCA > 5‐FU. The synthesized samples inhibited DNA replication and angiogenetic activity more than did 5‐FU. © 2001 Society of Chemical Industry     

马来海松酸类环氧树脂固化产物性能

本文研究了马来海松酸类环氧树脂与酸酐及芳香二胺类五种固化剂固化产物的耐热性能和机械性能,并详细讨论了固化后树脂的性能与环氧树脂、固化剂的化学结构及固化反应条件之间的关系。