Effect of functionality levels and compatibility of polycarbonate blends with maleic anhydride grafted ABS

ABS was melt grafted with maleic anhydride at three different levels of 1, 2, and 3 wt %. These three different modified ABSs were melt blended with polycarbonate using a single‐screw extruder to choose a suitable maleic anhydride grafting level on ABS for better performance. For the compatibility study, binary blends of polycarbonate with ABS and maleic anhydride‐grafted ABS were prepared over the entire range of compositions. Compatibility of these blends was studied using a Dynamic Mechanical Analyzer and by Differential Scanning Calorimetry. Both techniques suggest more partial compatibility for modified blend systems. In addition to this, DSC thermograms show multiple peaks between the transition points of ABS fractions and polycarbonate fractions for the polycarbonate/maleic anhydride‐grafted ABS blends. These multiple peaks are characteristic of better partial compatibility with fine microstructure. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 2102–2110, 1999     

Sol-gel synthesis of Ru(II) complex of 3-4,5-dihydroimidazol-1-yl-propyltriethoxysilane aerogels and xerogels

The preparation and the measurement of some properties of Ruthenium (II) coordinated 3-4,5-dihyroimidazol-1-yl-propyltriethoxysilane have been achieved. The organosilicon precursor chosen for this study was N-aminoethyl-3-aminopropyltriethoxysilane converted to 3-4,5-dihydroimidazol-1-yl-propyltriethoxysilane that was then coordinated with ruthenium (II). FT-IR spectroscopy, DTA and TGA analysis were used to characterize the bond formation during gelation, aging and drying of gels. The prepared aerogels are low-density 0.19–0.30 g/cm³ amorphous materials with surface areas of 405 to 530 m²/g. The resulting aerogel catalysts exhibited unique structural and chemical properties. Received: 29 August 1999/Revised version: 6 November 1999/Accepted: 29 November 1999     

Synthesis and testing of nonhalogenated alkyne/phosphorus-containing polymer additives: Potent condensed-phase flame retardants

In this article, the syntheses and thermal properties of several alkyne- and phosphorus-containing materials are discussed. The materials were synthesized using substituted phenolic molecules which were added to phosphorus oxychloride. The materials synthesized include phosphine oxides, phosphates, diphosphates, and oligophosphates. The thermal properties of the synthesized materials were studied using differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA). In general, the DSC and TGA data showed that synthesized materials containing alkynes and phosphorus had good-to-excellent thermal stability with high-onset decomposition temperatures. Materials with a high alkyne-to-phosphorus ratio showed the highest char yields. DSC data showed crosslinking events for the alkynes and the phosphorus moieties. DSC also showed that the alkynes crosslinked at lower temperatures than the phosphates. Based on the TGA and DSC data of the alkyne-containing phosphorus materials, alkynes generally appeared to be better char-inducing groups than was phosphorus. The materials were blended into polycarbonate and tested for ignition resistance using the UL-94 flame test. In two cases, these halogen-free compounds, with their dual alkyne/phosphorous crosslinking mechanisms, are condensed-phase flame retardants that can be easily blended into polycarbonate at 10 wt % loadings to afford blends that give a UL-94 V-0 rating. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 707–718, 1999     

Microporous anisotropic phase inversion membranes from bisphenol A polycarbonate: Effect of additives to the polymer solution

Phase inversion is a very flexible technique to obtain membranes with a large sort of morphologies. Membrane properties can vary greatly depending on the kind of polymer system used. Bisphenol A polycarbonate (PC) could be used as a phase inversion membrane base polymer, and presents very good properties. Nevertheless, very little information on membrane preparation using PC and the phase inversion process can be found in the literature. In this work flat‐sheet microporous membranes were obtained by the phase inversion process using the immersion precipitation technique. A new polymer system was studied, consisting of polycarbonate, N‐methyl‐2‐pyrrolidone as solvent, water as the nonsolvent, and an additive. The influence of some parameters on membrane morphology, such as polymer solution composition, exposition time before immersion into the precipitation bath, and the kind of additive was investigated. Precipitation was followed using light transmission experiments and membrane morphology was observed through Scanning Electron Microscopy (SEM). The viscosity and cloud points of all polymer solutions were also determined. The results were related to the studied synthesis parameters, using the basic principles of membrane formation by the phase inversion technique, looking forward to establishing criteria to control the morphology of flat‐sheet membranes using polycarbonate as the base polymer. The results showed that both additives were able to increase pore interconnectivity and even suppress macrovoid formation. The decrease in the miscibility region of the polymer system and increase in mass transfer resistance are found to be the determining factors during polymer solution precipitation. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 3085–3096, 2002     

Interaction-structure-property relationships in amorphous polymer blends

Summary Miscibility, structure and property relationships were studied by different techniques for various polymer pairs. Four blends of polystyrene (PS), styrene-acrylonitrile copolymer (SAN), polycarbonate (PC) and polyphenylene oxide (PPO) [PS/PPO, PS/PC, PS/SAN and PPO/SAN] were investigated in the entire composition range. Glass transition temperatures were measured by DSC, mechanical properties were characterized by tensile test, methanol absorption was determined at 50 °C. The Flory-Huggins interaction parameter (χ) was derived from Hildebrand solubility parameters, and compared to χ-related quantities calculated from the experimental results. Good correlation was obtained between parameters derived from different methods used for the characterization of polymer/polymer interaction. Received: 5 August 1999/Revised version: 20 March 2000/Accepted: 27 March 2000     

二氧化碳与环氧烷开环共聚催化剂研究进展

综述了二氧化碳与环氧烷开环共聚制备聚碳酸酯的各类催化剂的研究进展,指出了研制高效、制备工艺简单、廉价易回收的环境友好催化剂仍是合成聚碳酸酯这一利用方式的研究重点,为二氧化碳的减排和资源化利用提供参考。     

Incidence of the polyol nature in waterborne polyurethane dispersions on their performance as coatings on stainless steel

Three waterborne polyurethane dispersions derived from polyester, polyether and polycarbonate diols with molecular weight of 1000 Da were synthesized by the acetone method and used as coatings on stainless steel 304 plates. The properties of the dispersions and the polyurethane films were influenced by the polyol nature. The polyurethanes obtained with polyether or polyester showed higher degree of phase separation between the soft and the hard segment. The higher adhesive strength under shear stresses was obtained in the joints produced with the waterborne dispersion obtained with polycarbonate diol. The properties of the polyurethane coating obtained with polycarbonate diol on stainless steel 304 were significantly higher as compared with the others. Improved performance of coatings obtained with polycarbonate diol was ascribed to the higher polarity of the carbonate groups that contributed to additional hydrogen bond formation between soft segments with respect to those obtained with polyether or polyester     

Microcavity formation in engineering polymers exposed to hot water

Microcavity formation in engineering polymers exposed to boiling water has recently been noted in the technical literature. This study describes this observation and presents photomicrographs of the microcavity morphology. The microcavities are lens-shaped cracks emitting from a nucleation site with regular concentric ridges observed at regular intervals with characteristics similar to fatigue cracking. Cyclic exposure [intervals of hot (96deg;C) followed by cold (23°C) water immersion] was found to significantly increase the microcavity formation in specific polymers. Polymers studied under these conditions included polycarbonate, polysulfone, poly(ether sulfone), and polyetherimide. Only polycarbonate and polyetherimide exhibited internal crack formation. The microcavities of polyetherimide were quite different than those of polycarbonate as the cracks were concentrated in regions of highest molded-in stress. When polysulfone was purposely spiked with 0.1 wt % NaCl inclusions, microcavity formation was observed but at a magnitude significantly lower than that of polycarbonate (unmodified). A hypothesis is presented to explain this failure mechanism in polycarbonate. Localized regions, (nucleation sites) of higher water solubility can result in higher internal pressure and stress-induced hydrolysis causing microcavity formation. Additional internal pressure (cyclic conditions) can result from water phase separation yielding further crack propagation. Polycarbonate exhibits a larger difference in equilibrium water solubility between 23°C and 96°C than do the other plymers studied, thus yielding a greater potential for internal pressure resulting from phase separation.     

Thermal and mechanical properties of multiple‐component aliphatic degradable polyurethanes

Macroscopic thermal and mechanical properties of complex aliphatic polycarbonate‐based polyurethane (PU) films containing degradable ester units in PU backbone were studied by a combination of several experimental techniques. Differential scanning calorimetry (DSC) revealed that the synthesized oligomeric diol (DL‐L) contributes (in addition to polycarbonate diol) to the formation of soft‐segment domains, while the hard‐segment domains are formed from 1,6‐diisocyanatohexane (HDI) and butane‐1,4‐diol (BD). Three main phase transitions were detected by DSC and by dynamic mechanical thermal analysis. Thermogravimetric analysis (TGA) of two‐component PUs showed that the PU made from DL‐L and HDI is the least thermostable product, while the PU made from polycarbonate diol and HDI is the most stable one. The differences in the thermal stability of different four‐component PUs are not important. Tensile properties very sensitively reflect the changes in composition and in microstructure of PU samples; the best tensile properties exhibits the degradable sample containing the equimolar ratio of hydroxyl groups of macrodiol, oligomeric diol DL‐L and butane‐1,4‐diol. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41872.     

酯交换法合成聚碳酸酯催化剂性能考察

以双酚A和碳酸二苯酯为原料,采用非光气熔融酯交换法合成聚碳酸酯。考察了氢氧化钾、氢氧化钠、四丁基氢氧化铵、碳酸钠、吡啶以及复合催化剂对聚碳酸酯合成反应速率及聚碳酸酯分子量和色差的影响。研究表明,氢氧化钾作为催化剂较适合于聚碳酸酯合成工艺,使用复合催化剂可以得到分子量较高、色差较低的聚碳酸酯。     

Assessment of relative flammability and thermochemical properties of some thermoplastic materials

The thermochemical and flammability characteristics of some typical thermoplastic materials currently in use and others being considered for use in aircraft interiors are described. The properties studied included (a) thermal mechanical properties such as glass transition and melt temperature, (b) changes in polymer enthalpy by differential scanning calorimetry, (c) thermogravimetric analysis in an anaerobic and oxidative environment, (d) oxygen index, (e) smoke evolution, (f) relative toxicity of the volatile products of pyrolysis, and (g) selected physical properties. The generic polymers which were evaluated included: acrylonitrile-butadiene-styrene, bisphenol A polycarbonate, bisphenol fluorenone carbonate-dimethylsiloxane block polymer, phenolphthalein-bisphenol A polycarbonate, phenolphthalein polycarbonate, polyelher sulfone, polyphenylene oxide, polyphenylene sulfide, polyaryl sulfone; chlorinated poly vinyl chloride homopolymer, polyvinyl fluoride, and polyvinylidene fluoride. Processing parameters including molding characteristics of some of the advanced polymers are described. Test results and relative rankings of some of the flam inability, smoke and toxicity properties are presented. Under these test conditions, some of the advanced polymers evaluated were significantly less flammable and toxic or equivalent to polymers in current use. A relationship of the anaerobic char yield of the polymers to their relative flammability properties is shown.     

Synthesis and characterization of poly(lactic acid) and aliphatic polycarbonate copolymers

BACKGROUND: Poly(lactic acid) (PLA) has received much attention as a biodegradable polymer. But the physical properties of PLA, such as brittleness, limit its wider applicability. Copolymerization polymers ing soft blocks provides a useful method to improve the mechanical properties of PLA. RESULTS: Poly(lactic acid)‐block‐(polycarbonate diol) (PLA‐PCD) copolymers were synthesized using a two‐step process with polycondensation and chain extension reactions. The effect of polycarbonate diol content on the prepolymer properties was studied. The chain‐extended products were characterized using ¹H NMR, F and. The effect of the NCO/OH ratio on the properties of the chain‐extended products, including the mechanical properties and thermal properties, was studied. eight‐average molecular weight of the product can reach 210 000 g mol^?1 when the molar ratio of ? NCO to ? OH is 3:1. CONCLUSION: The PLA‐PCD copolymers obtained can crystallize, and the crystallinity decreases with chain‐extension reaction. The products exhibit superior mechanical properties with elongation at break above 230%, which is much higher than that of PLA chain‐extended products. The products have a good potential for packaging applications. Copyright © 2009 Society of Chemical Industry     

制备条件对肉桂醛选择加氢Co-Fe/硅藻土催化剂的影响

对肉桂醛选择加氢制肉桂醇的Co-Fe/硅藻土催化剂的制备条件进行了研究,并对超声波作用下制备的催化剂的催化性能优化进行了探讨。通过催化反应评价和SEM、XRD及正电子寿命谱的测定等表征,结果表明,焙烧温度和还原温度对Co-Fe/硅藻土催化剂的催化性能影响较大,不但可改变催化剂的晶体结构,也能对载体及载体与催化剂的作用产生影响。最佳焙烧温度为673 K,还原温度为723 K。制备过程中引入超声技术,使催化剂的晶形细化并在载体上更好铺展,有利于改善和提高催化性能。     

Blends of bisphenol A polycarbonate and rubber‐toughened styrene–maleic anhydride copolymers

The morphology and mechanical properties of polycarbonate (PC) blends with rubber‐toughened styrene–maleic anhydride copolymer materials (TSMA) were investigated and compared with the properties of blends of PC with acrylonitrile–butadiene–styrene (ABS) materials. The PC/TSMA blends showed similar composition dependence of properties as the comparable PC/ABS blends. Polycarbonate blends with TSMA exhibited higher notched Izod impact toughness than pure PC under sharp‐notched conditions but the improvements are somewhat less than observed for similar blends with ABS. Since PC is known for its impact toughness except under sharp‐notched conditions, this represents a significant advantage of the rubber‐modified blends. PC blends with styrene–maleic anhydride copolymer (SMA) were compared to those with a styrene–acrylonitrile copolymer (SAN). The trends in blend morphology and mechanical properties were found to be qualitatively similar for the two types of copolymers. PC/SMA blends are nearly transparent or slightly pearlescent. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 1508–1515, 1999     

Synthesis,flame‐retardancy testing,and preliminary mechanism studies of nonhalogenated aromatic boronic acids: A new class of condensed‐phase polymer flame‐retardant additives for acrylonitrile–butadiene–styrene and polycarbonate

This study describes the syntheses and thermal properties of aromatic boronic acids and their use as flame retardants. The possible flame‐retardancy mechanisms are also discussed. The materials were synthesized from aromatic bromides using one of two procedures. The first procedure involved traditional approaches to boronic acids, using lithium–halogen exchange and quenching with trimethylborate followed by hydrolysis. The second procedure used a nickel catalyst and a dialkoxy borane to generate aromatic dialkoxyboronates that were converted to boronic acids by acid hydrolysis. The thermal properties of these aromatic boronic acids were studied using differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA). These materials were blended into acrylonitrile–butadiene–styrene (ABS) and polycarbonate (PC) resins and tested for ignition resistance, using the UL‐94 flame test. A 10 wt % loading of 1,4‐benzenediboronic acid in polycarbonate gave a UL‐94 V‐0 result. This same diboronic acid showed flame retardancy and char formation in ABS, but this result was not quantifiable by the UL‐94 test. Burn times for the ABS samples often exceeded 5 min, thereby showing unusual resistance to consumption by fire. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 76: 1257–1268, 2000     

Influence of preparation method and boron addition on the metal function properties of Ru?Sn catalysts for selective carbonyl hydrogenation

BACKGROUND: Improvements in the selective hydrogenation of unsaturated fatty acid methyl esters in order to obtain unsaturated fatty alcohols have been attempted through the preparation and modification of supported group VIII metallic catalysts. Suitable catalysts appear to be those based on supported Ru modified by Sn. The influence of preparation and activation methods on the structural and electronic properties of the metallic phase and the effect of modifications to these properties on the catalytic performance of Ru? Sn/Al₂O₃ catalysts was studied regarding selective hydrogenation of carbonyl groups. RESULTS: Preparation methods have a marked influence on the electronic state of Ru and its interaction with Sn. Temperature‐programmed reduction (TPR), Fourier transform infrared spectroscopy of chemisorbed CO (FTIR‐CO) and X‐ray photoelectron spectroscopy (XPS) results clearly show that the incorporation of sodium borohydride in the preparation leads to a greater Ru? Sn interaction when compared with catalysts prepared by co‐impregnation without B. The activation of catalysts without B (either by direct reduction or calcinations‐reduction) does not produce a strong Ru? Sn interaction. B‐containing catalysts exhibit higher hydrogenolytic and lower dehydrogenating activities. Selectivity towards oleyl alcohol formation was 37% for this catalyst, while catalysts without B were not suitable for obtaining fatty alcohols. CONCLUSION: The degree of interaction between Ru and Sn strongly depends on catalyst preparation and activation method where strong interaction promotes selectivity with respect to oleyl alcohol formation. On the contrary, catalysts with a weak Ru? Sn interaction do not show significant selectivity for the unsaturated alcohol. Copyright © 2010 Society of Chemical Industry     

Morphologies and properties of polyblends: 1. Blends of poly(methylmethacrylate) and a chlorine-containing polycarbonate

The morphologies and dynamic mechanical properties of blends of poly(methylmethacrylate) and a chlorine-containing polycarbonate, cast from dichloromethane solutions, have been studied. The results are discussed in terms of a phase diagram which has been determined for the system. It is demonstrated that the blends do not have equilibrium morphologies, which are virtually impossible to attain: nevertheless, their properties and morphologies can be related to the phase diagram and sample histories. Apparently anomolous variations in miscibility with composition are shown to be a consequence of an assymetric phase diagram and preferential solubility of polycarbonate in poly(methylmethacrylate).     

Synthesis of polycarbonate‐co‐poly(p‐ethylphenol) and CdS nanocomposites

The enzyme‐catalyzed synthesis of poly(p‐ethylphenol) (PEP) was modified by copolymerization with polycarbonates through triphosgene at low temperature to form polycarbonate‐co‐poly(p‐ethylphenol) (PC‐co‐PEP). FTIR, NMR, GPC, and thermal analysis verified the formation of PC‐co‐PEP. The copolymers have an optical absorption in the UV range. CdS semiconductor nanocrystallites were synthesized in reversed micelles with subsequent in situ enzymatic copolymerization of p‐ethylphenol and 4‐hydroxythiophenol in the same medium. TEM and ATR–FTIR showed that the polymer precipitated in spherical morphologies, incorporating CdS nanocrystals into the polymer matrix, with surface hydroxyl groups. The polymer/CdS core was then dispersed into polycarbonate. The polymer/CdS nanocomposites showed higher optical aborbance in the UV‐vis range when compared to the polymer matrix without CdS. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 72: 1851–1868, 1999     

Pervaporation of aqueous alcohol solution through a polycarbonate/(DMF/metal salt) complex membrane prepared via a wet-phase inversion method

A polycarbonate (PC)/(DMF/metal salt) complex membrane was utilized in the pervaporation of alcohol/water mixtures. The effects of the presence of metal salt in the casting solution, the polycarbonate concentration, and the kinds of coagulation media on the formation of membranes were studied. In addition, the effects of feed composition, size of the alcohol, and the degree of swelling on the pervaporation performances were investigated. Compared with the membrane without additive, the PC/(DMF/metal salt) complex membrane shows an improvement in the pervaporation separation index (PSI). © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 68: 1191–1198, 1998     

Tensile properties of natural fabric Hildegardia populifolia/polycarbonate toughened epoxy composites

The environmentally friendly composites of natural fabric Hildegardia populifolia/polycarbonate toughened epoxy were prepared. The effect of fabric content and the orientation of the fibers in the fabric on the tensile properties of the composites was studied. The effect of alkali treatment of the fabric and a silane coupling agent on the tensile properties was also studied. The tensile properties improved with alkali treated fabric content when a coupling agent was used. Polym. Compos. 25:563–568, 2004. © 2004 Society of Plastics Engineers.