Unsaturated polyesters based on terephthalic acid: 2. Quantitative characterization of prepolymers by proton magnetic resonance spectroscopy

Integrated proton magnetic resonance spectra have been obtained for poly(propylene terephthalate) prepolymers prepared by the polyesterification of terephthalic acid with excess propylene glycol. From the peaks for the phenyl hydrogens and the methyl hydrogens, the molecular weight of the terephthalate-based components of the prepolymer is determined. The procedure may be extended to the determination of the molecular weight of all components, including excess propylene glycol. Methods for determining the concentration of excess propylene glycol and the quantity of propylene glycol lost during polyesterification are also presented.     

Unsaturated polyesters based on terephthalic acid: 1. Proton magnetic resonance spectrum of poly(propylene terephthalate) prepolymer

Peaks in the proton magnetic resonance spectrum of the prepolymer prepared by the polyesterification of terephthalic acid with excess propylene glycol are assigned to the methyl, methylene and methine protons in propylene glycol units which may exist in four different environments. The assignments are confirmed by removing the excess propylene glycol from the prepolymer, by benzoylating the prepolymer, and by obtaining spectra for isopropanol, isopropyl benzoate, propylene glycol 1,2-dibenzoate, propylene glycol, and bis(2-hydroxypropyl) terephthalate.     

Preparation and properties of bio-based epoxy networks derived from isosorbide diglycidyl ether

Two bio-based epoxy prepolymers were synthesized from isosorbide, a carbohydrate-based C6 building block, using two different synthetic routes. The chemical structures of the bio-based epoxy prepolymers were analyzed by SEC, ESI-TOF MS, FTIR, ¹H NMR and ¹³C NMR analysis. The resulting epoxy prepolymers differ by the molar mass distribution, one consists of the pure epoxy monomer whereas the other exhibits various oligomeric species. A traditional petroleum-based epoxy prepolymer, DGEBA, which has similar epoxy equivalent weight, was also used in this study for comparison. Gelation and crosslinking reactions of the two bio-based epoxy precursors with an amino hardener, isophorone diamine, were studied using rheological measurements and differential scanning calorimetry (DSC) respectively; the effect of the stoichiometric ratio n_ah/n_e was investigated. Structures of the epoxy networks were evaluated using dynamic mechanical analysis (DMA) and thermo gravimetric analysis (TGA).     

The synthesis of lactic-acid-based telechelic prepolymers

We have studied how different catalysts and diols affect the properties of low-molecular-weight (M_w (GPC) < 49800 g/mol) lactic-acid-based telechelic prepolymers. The catalysts and diols were tested separately in our previous studies. In this study, we used the best previously tested diols and catalysts together in order to prepare different types of telechelic prepolymers (for example, crystalline or amorphous). All condensation polymerizations were carried out in the melt, using different diols and different catalysts. The prepolymers were characterized by differential scanning calorimetry, gel permeation chromatography, titrimetric methods, and ¹³C nuclear magnetic resonance (¹³C-NMR). According to NMR, the resulting polymers contained less than 1 mol % of lactic acid monomer and less than 5.1 mol % of lactide. Dibutyltindilaurate, like tin(II)octoate, produced quite good molecular weights, but the resulting prepolymers contained exceptionally high amounts of D-lactic acid structures, and, therefore, these prepolymers were totally amorphous. Antimony(III)oxide produced a high-molecular-weight prepolymer when the diol used was aliphatic. Like DBTL, Sb₂O₃ produced amorphous prepolymers, which contained a lower amount of D-lactic acid structures than DBTL prepolymers. 1,8-dihydroxyanthraquinone produced a different kind of chain structure with Ti(IV)bu and Ti(IV)iso because one prepolymer had high crystallinity, and the other showed only a slight crystallinity. Sulphuric acid produced a very high-molecular-weight prepolymer with aliphatic 2-ethyl-1,3-hexanediol; and with aromatic diols, it produced quite good molecular weights, except with 1,8-dihydroxyanthraquinone. High-molecular-weight prepolymers produced with H₂SO₄ also showed high crystallinity; and, according to ¹³C-NMR, they did not contain lactide and D-lactic acid structures. © 1998 John Wiley & Sons, Inc. J Appl Polm Sci 67:1011–1016, 1998     

Unvernetzte epoxid-amin-additionspolymere, 16. HPLC-analyse und 13C-NMR-spektroskopie von telechelen (diglycidylether-bisphenol A)-anilin-prepolymeren

Synthesis and properties of telechelic diglycidyletherbisphenol A (DGEBA)-aniline prepolymers with aminoalcohol endgroups are reported. The composition of the prepolymer mixtures obtained by addition polymerization was analyzed by means of HPLC using a LiChrosorb RP-18 column with water/acetonitrile gradient elution mode. The prepolymers represent a series of homologous oligo(aminodiols) 2 , n = (1), 2, 3, 4 ... which are separated into diastereomers. The average value n? depends on the molar ratio of the monomers and is varied between 1,0 and 14,0 resulting in M?_n (vapor pressure osmometry) 500–6000 g · mol^-1. C, H, N elemental analysis and ¹³C-NMR spectroscopy were used to estimate the chemical structure of the prepolymer mixtures.     

Aqueous reactive polyurethane prepolymer with poly(ethylene oxide) monomethyl ether side chains for the hydrophilic finishing of poly(ethylene terephthalate) fabrics

In this study, a series of aqueous polyurethane (PU) prepolymers were synthesized with 4,4‐methylene bis(isocyanatocyclohexane), poly(ethylene glycol) or polycaprolactone diol (PCL), methyl ethyl ketoxime, and dispersing centers produced by isophorone diisocyanate, N‐diethanol amine, and poly(ethylene oxide) monomethyl ether (PEO), containing different hydrophobic groups (? CH₃ and ? C₆H₄C₉H₁₉) at the end. The thermal properties of the prepolymers and the characteristics of poly(ethylene terephthalate) (PET)‐treated fabrics were investigated. The glass‐transition temperature was the highest in the CC prepolymer containing a benzene ring (? C₆H₄C₉H₁₉) and a long PEO side chain, and it was the lowest in the CA prepolymer having a longer PEO side chain. The CB prepolymer containing a shorter PEO side chain did not produce a melting point of PEO, although a heat endothermic peak of the PCL crystal appeared. The melting point and enthalpy from PEO of the CA prepolymer were larger than those of the CC prepolymer. With respect to the hydrophilic finishing effects of aqueous PU prepolymers for PET fabrics, the fabric treated with the CB prepolymer had higher add‐on and washing durability than the fabrics treated with the CA prepolymer, which was followed by the CC prepolymer with the lowest, but the opposite trend was found for the hydrophilic properties. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

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     

Synthesis and characterization of poly(ester ether siloxane)s

A series of novel thermoplastic elastomers based on ABA‐type triblock prepolymers, poly[(propylene oxide)–(dimethylsiloxane)–(propylene oxide)] (PPO‐PDMS‐PPO), as the soft segments, and poly(butylene terephthalate) (PBT), as the hard segments, was synthesized by catalyzed two‐step melt transesterification of dimethyl terephthalate (DMT) with 1,4‐butanediol (BD) and α,ω‐dihydroxy‐(PPO‐PDMS‐PPO) (M?_n = 2930 g mol^?1). Several copolymers with a content of hard PBT segments between 40 and 60 mass% and a constant length of the soft PPO‐PDMS‐PPO segments were prepared. The siloxane‐containing triblock prepolymer with hydrophilic terminal PPO blocks was used to improve the compatibility between the polar comonomers, i.e. DMT and BD, and the non‐polar PDMS segments. The structure and composition of the copolymers were examined using ¹H NMR spectroscopy, while the effectiveness of the incorporation of α,ω‐dihydroxy‐(PPO‐PDMS‐PPO) prepolymer into the copolyester chains was controlled by chloroform extraction. The effect of the structure and composition of the copolymers on the transition temperatures (T_m and T_g) and the thermal and thermo‐oxidative degradation stability, as well as on the degree of crystallinity, and some rheological properties, were studied. Copyright © 2006 Society of Chemical Industry     

Synthesis, characterization and properties of chitosan modified with poly(ethylene glycol)-polydimethylsiloxane amphiphilic block copolymers

Synthesis of poly(ethylene glycol)-polydimethylsiloxane amphiphilic block copolymers is discussed herein. Siloxane prepolymer was first prepared via acid-catalyzed ring-opening polymerization of octamethylcyclotetrasiloxane (D₄) to form polydimethylsiloxane (PDMS) prepolymers. It was subsequently functionalized with hydroxy functional groups at both terminals. The hydroxy-terminated PDMS can readily react with acid-terminated poly(ethylene glycol) (PEG diacid) to give PEG-PDMS block copolymers without using any solvent. The PEG diacid was prepared from hydroxy-terminated PEG through the ring-opening reaction of succinic anhydride. Their chemical structures and molecular weights were characterized using ¹H NMR, FTIR and GPC, and thermal properties were determined by DSC. The PEG-PDMS copolymer was incorporated into chitosan in order that PDMS provided surface modification and PEG provided good water swelling properties to chitosan. Critical surface energy and swelling behavior of the modified chitosan as a function of the copolymer compositions and contents were investigated.     

The effect of prepolymer crystallinity on solid-state polymerization of poly(bisphenol A carbonate)

The effect of prepolymer crystallinity on the solid-state polymerization (SSP) of poly(bisphenol A carbonate) was examined using nitrogen as a sweep fluid. A low-molecular-weight prepolymer was synthesized by melt transesterification and prepolymers with different crystallinities (11.7%, 23.3%, 33.7%) were prepared with supercritical carbon dioxide treatment. SSP of the three prepolymers was then carried out at reaction temperatures in the range of 150-190 °C, with a prepolymer particle size of 75 μm and a N₂ flow rate of 1600 ml/min. The glass-transition temperature (T_g), absolute weight-average molecular weight (M_n), and percent crystallinity were measured at various times during each SSP. At each reaction temperature, SSP of the lower crystallinity prepolymer (11.7%) always resulted in higher-molecular-weight polymers, compared with the polymers synthesized using the higher crystallinity prepolymer (23.3% and 33.7%). The crystallinity of the polymers synthesized from the high crystallinity prepolymer was significantly higher than for those synthesized from the low crystallinity prepolymer. Higher crystallinity of the prepolymer and the synthesized polymers may lower the reaction rate by reducing chain-end mobility or/and by inhibiting byproduct diffusion.     

Dithioles—constituents for telechelic prepolymers with glycidyl or thiol endgroups

Summary Telechelic prepolymers 2–5 containing thiol-or glycidyl endgroups, respectively are obtained by addition polymerization of dithiols 1a-1f and diglycidylether of bisphenol-A (DGEBA). They have molecular weights of 800 to 2000 g/mol. The structure of the prepolymers is determined by combination of elemental analysis, M_n (VPO)-values, IR-, ¹H-NMR-and ¹³C-NMR spectroscopy. By means of TLC and HPLC these prepolymers were shown to be a mixture of a series of homologous compounds. Furthermore, their oligomer distribution is analysed.     

The hydrogenation of HO-terminated telechelic polybutadienes in the presence of a homogeneous hydrogenation catalyst based on tris(triphenylphosphine)rhodium chloride

The hydrogenation kinetics of multiple bonds in HO-terminated telechelic polybutadienes was investigated using two types of these prepolymers prepared by the anionic and radical polymerization. The rate of addition of hydrogen to the π-bonds of these polydienes in the presence of tris(triphenylphosphine) rhodium chloride as a homogeneous hydrogenation catalyst was determined by the chemical structures of the starting polydienes, their concentration in the solvent, the partial hydrogen pressure, the concentration of the catalyst, and the temperature. The effect of kinetic parameters given above on the rate of hydrogenation reaction can be interpreted in the sense of Wilkinson's reaction mechanism of the hydrogenation of alkenes in the presence of the Rh(I)-complex. Due to the predominant 1,2-structural units, the anionic prepolymer reacted twice as quickly with hydrogen (k = 0.093 mol^?1 dm³ s^?1) compared with the radical prepolymer (k = 0.045 mol^?1 dm³ s^?1). During the hydrogenation of multiple bonds there is a partial loss of hydroxy groups in modified telechelic prepolymers; the extent of this reaction depends on reaction conditions of the hydrogenation reaction.     

SOLUBILITIES,DENSITIES, AND REFRACTIVE INDICES FOR THE TERNARY SYSTEMS 1,2-PROPYLENE GLYCOL + MNO3 + H2O (M = Na,K, Rb,Cs) AT 25° AND 35°C

The solubilities, densities, and refractive index data for the 1,2-propylene glycol + MNO₃ + H₂O (M = Na, K, Rb, Cs) ternary systems at 25° and 35°C were measured with mass fractions of 1,2-propylene glycol ranging from 0 to 1.0. In all cases, the presence of 1,2-propylene glycol significantly reduces the solubility of the salts in aqueous solution. The experimental data of density, refractive index, and solubility of saturated solutions for these systems were correlated using polynomial equations. Furthermore, the refractive index and density of unsaturated ternary solutions were also determined and correlated with the salt concentrations and proportions of 1,2-propylene glycol in the systems.     

对甲苯磺酸铜催化合成香兰素1,2-丙二醇缩醛的研究

以香兰素和1,2-丙二醇为原料,对甲苯磺酸铜为催化剂,苯为带水剂,合成了香兰素1,2-丙二醇缩醛。考察了原料摩尔比、催化剂用量和反应时间等因素对产品收率的影响。结果表明:对甲苯磺酸铜具有良好的催化活性,且可重复使用3次。最佳工艺条件为:香兰素15.2 g(0.1 mol),n(香兰素):n(1,2-丙二醇)=1∶1.60,对甲苯磺酸铜0.9 g,苯25 mL,反应时间2.5 h条件下,产品收率达到87%以上。     

PP或PE用双组分PU胶粘剂的制备与性能研究

以聚酯多元醇、混合异氰酸酯(MDI/TDI)、扩链剂(1,2-丙二醇)、异氰酸酯固化剂(TMP-TDI)和溶剂(乙酸乙酯)等为主要原料,制备了PP(聚丙烯)、PE(聚乙烯)粘接用双组分PU(聚氨酯)胶粘剂。研究结果表明:当m(结晶性聚酯多元醇)∶m(非结晶性聚酯多元醇)=80∶20~60∶40、R=n(-NCO)/n(-OH)=0.95~0.97、m(MDI)∶m(TDI)=90∶10~60∶40和w(功能性聚酯多元醇XCP-2325)=2%时,PU预聚体的相对分子质量为(9~11)×104,其常温固化12 h后的邵A硬度(76)有利于PU预聚体的破碎;当PU预聚体/乙酸乙酯溶液的固含量为12%时,双组分PU胶粘剂的操作性能(黏度为22 mPa.s)、180°剥离强度(初始2.3 N/25 mm、最终41.0 N/25 mm)俱佳。     

Glycolyzed poly(ethylene terephthalate) waste and castor oil-based polyols for waterborne polyurethane adhesives containing hexamethoxymethyl melamine

Glycolysis of poly(ethylene terephthalate) (PET) waste using different molar ratio of poly(ethylene glycol) (PEG400), was used to produce saturated hydroxyl-functional polyester polyols with castor oil (CO) by transesterification process. The waterborne polyurethane (WBPU) adhesives were synthesized from these saturated polyester polyols, isophorone diisocyanate (IPDI), dimethylolpropionic acid (DMPA), and hexamethoxymethyl melamine (HMMM) as cross-linking agent by a conventional prepolymer process. The glycolyzed polyols and polyester polyos formations were characterized using Fourier transform infrared spectroscopy (FTIR) and the molecular weights were determined using gel permeation chromatography (GPC). The cross-linking reaction between WBPU and HMMM was verified using FTIR and ¹H NMR analysis. Thermal properties were investigated by thermogravimetric analysis (TG). Thermal stability of cross-linked WBPU significantly increased with decreasing castor oil content in the process of transesterification to obtain polyester polyol as a soft segment. The T_15% and T_50% (the temperature where 15 and 50% weight loss occurred) of WBPU increased with the decreasing of castor oil content in the obtained polyester polyols, caused by the steric hindrance of polyester polyol with higher castor oil content, in the process of cross-linking reactions with HMMM. The physico-mechanical properties of WBPU, such as hardness, adhesion test, and gloss of the dried films were also determined considering the effect of participation of HMMM in cross-linking reactions with polyurethane, on coating properties.     

13C and 1H n.m.r. study of the polyesterification of maleic anhydride and 1,2-propylene glycol

The reaction steps of the polyesterification of maleic anhydride and 1,2-propylene glycol were followed by ¹³C and ¹H n.m.r. spectroscopy. The number and structure of mono- and diesters of both maleates and fumarates in the reaction mixture are determined by the possible glycol unit configurations. The structure of the growing polyester chain reflects a statistical distribution of approximately equal numbers of symmetric and asymmetric arrangements of the polymer sequences.     

引进1,2-丙二醇共聚单体制备新型共聚酯的研究

采用直接酯化工艺路线,以对苯二甲酸、乙二醇、1,2-丙二醇为原料合成了一种新型共聚酯——聚对苯二甲酸丙二醇酯-co-对苯二甲酸乙二醇酯(PPET)。研究了该共聚酯的聚合工艺条件,并对制备的共聚酯进行了性能测试。结果表明:共聚酯聚合工艺受总醇与酸的摩尔比、催化剂种类和用量、稳定剂用量、聚合温度等条件的影响;新型共聚酯注塑性能较好,并具有一些特殊性能。     

Allylic prepolymers from brassylic and azelaic acids

Diallyl brassylate (DAB), a new monomer, and diallyl azelate (DAA) were converted to new prepolymers for comparison with analogous commercial products from diallyl o-and m-phthalate (DAMP). Respective prepolymers from DAB and DAA had M?_n 28,000 and 40,000 and contained approximately 0.8 free allyl moiety per repeating unit. Only the DAB prepolymer exhibited crystallinity at low temperatures as detected by differential scanning calorimetry and x-ray diffraction. Aliphatic prepolymers have greater heat stability than aromatic ones and evolve fewer calories per double bond during curing than reported for DAMP prepolymer. Low shrinkage (<1%) on curing and clear, hard end products indicate the potential of aliphatic prepolymers as thermosetting plastics. Their liquid state at room temperature should be advantageous in many applications.     

Rheological behavior of molten epoxide prepolymers

Flow properties of four molten epoxide prepolymers of number average molecular weight 900(I), 1,500(II), 2,100(III) and 4,000(IV), were measured at temperatures ranging from 361 to 463K, and shear rates from 500 to 10,000 s^?1. Apparent shear viscosities showed that all prepolymers used have Newtonian behavior up to shear rates of 2,000 s^?1. Shear thinning occurs at higher shear rates. Flow activation energies at constant shear rates in the range of 500 to 7,000 s^?1 vary for prepolymer III from 5 to 24 kcal/mol, and for prepolymer IV from 9 to 25 kcal/mol. Flow indices in the same shear rate range vary for prepolymer III from 1.0 to 0.7 and for prepolymer IV from 1.0 to 0.3.