Zum spezifischen brechungsinkrement von homo- und copolymerlösungen

With the assumption of additivity of the specific refractivities of monomer units in a polymer and of solvent and solute theoretical expressions for the specific refractive index increments of homo-, co-, ter- and higher multipolymers are derived. They give the specific refractive index increments as functions of the refractive index of solvents, of the specific refractivity of the polymers, of the compositions of multipolymers, of the wave length and of the partial specific volumes of the polymers in infinitely dilute solutions. The theory is confirmed by experimental results obtained with solutions of methacrylate/styrene-, methacrylate/benzylacrylate- and ethylacrylate/methylmethacrylate-copolymers and of the corresponding homopolymers. It is shown that the formulas derived can be used for accurate determinations of the compositions of co- and other multipolymers from measurements of their specific refractive index increments.     

Characterization of ethylene homo- and copolymers

Summary For (norbornene ethylene) copolymers with a preferably alternating structure two methods for the determination of chemical composition were tested: the differential refractometry (DR) and the differential scanning calorimetry (DSC). It was found, that the refractive index increments measured by DR in 1,2,4-trichlorobenzene can be calculated by adding the refractive index increments of the homopolymers with regard to the composition of the copolymers. This was proved by comparing with results obtained by 1H-NMR-measurements. The temperatures of the glass transition determined by DSC yield a straight line correlation to the chemical composition. Errors of both methods due to the influence of molecular masses are negligible and of significance only in the range of low molecular masses.Part V: Polymer Bull. 15, 551 (1986)     

Lösungseigenschaften und spezifische Brechungs-inkremente von p-Jodstyrol/Styrol-Copolymeren

Measurements of the second virial coefficient as function of the copolymer composition show, that the parameter χ_AB, which characterizes the energy of interaction of heterocontacts, is negative for random p-iodostyrene/styrene copolymers. This means there exist weak attractive intramolecular interaction forces between the two different monomer units. Fractionation of the copolymers yields STOCKMAYER-FIXMAN-plots, which confirm this result. Measurements of the specific refractive index increments as function of the wave length show, that for these copolymers, in the region from red to ultraviolet light, the specific refractive index increment is additive.     

Studies on agaroses; 1. Specific refractive index increments in dimethyl sulfoxide and in water at various wavelengths and temperatures

Specific refractive index increments of three agarose samples in dimethyl sulfoxide and in water were measured at 436, 546 and 633 nm, and at several temperatures. The wavelength and temperature dependences of the increments were determined, simultaneously correlated using the surface regression method, and presented in a form suitable for tabulation. The influence of differences in the structure of agaroses from various algal sources on the specific refractive index increment is discussed.     

SPECIFIC REFRACTIVE INDEX INCREMENTS OF POLYURETHANE/POLYDIMETHYLSILOXANE SEGMENTED COPOLYMERS

New polydimethylsiloxane-containing segmented block copolyure-thanes were obtained from aromatic or aliphatic diisocyanates, 1,4-butanediol and poly(ethylene glycol)adipate using a multistep polyaddition process. Specific refractive index increments of these segmented copolymers in N,N-dimethyl-formamide have been determined by the Lorenz-Lorentz equation and the corresponding group contributions to the molar refraction and to the molar volume. The results are in good agreement with the experimental values. Also, from the dependence between the specific refractive index increments and the weight fraction of 4,4′-methylene diphenylene diisocyanate units, w _d , the ν₀ and dν/dw _d coefficients have been evaluated and the results are situated between the values reported in literature.     

Specific refractive index increments of certain polysaccharide systems

The specific refractive index increments of amylose, amylose acetate, amylopectin and glycogen in various aqueous and non-aqueous solvents have been determined. These were measured by the direct determination of deviation method.     

Characterization of acrylonitrile-butadiene-styrene terpolymers by computer aided FT-IR spectroscopy

The fast identification and accurate characterization of acrylonitrile-butadienestyrene (ABS) terpolymers by computer aided Fourier transform infrared spectroscopy is described. Samples are prepared as films from chloroform suspensions and identified by a library search routine after FTIR measurement. Calibration curves of monomer specific absorptions obtained from physical mixtures of a known terpolymer with different amounts of the corresponding homopolymers are used to quantify the incorporation ratios of unknown ABS systems.     

Study of segmented ethylene terephthalate–caprolactone copolymer by differential refractometry and light scattering

A segmented ethylene terephthalate (ET)–caprolactone (CL) copolymer was characterized by light scattering in chloroform tetrahydrofuran and butanone. The flexibility of the copolymer chain is comparable with that of typical flexible chains, such as polystyrene. In the process of applying the Bushuk–Benoit light scattering theory to the segmented PET–PCL copolymer, we encountered not only the problem of finding three solvents with different refractive index but also the problem of determining the specific refractive index increments for the PET and PCL segments in the copolymer, i.e., ν_PET and ν_PCL . In principle, the approximate values of ν_PET and ν_PCL can be obtained from the PET and PCL homopolymers, respectively. In reality, it involves many practical problems, e.g., to find three solvents not only for copolymer but also for the PET and PCL homopolymers. In this study, a different method was used to find both ν_PET and ν_PCL , wherein the ν values of at least two segmented PET–PCL copolymers with different PET compositions were used. With ν_PET , ν_PCL , and ν, we characterized the absolute molecular weight. Further, we show that the composition of an unknown segmented PET–PCL copolymer can be estimated from ν_PET , ν_PCL , and ν. © 1994 John Wiley & Sons, Inc.     

Poly[(2-ethylhexyl acrylate)-ran-(tert-butyl acrylate)]-block-poly(2-cinnamoyloxyethyl acrylate) synthesis and properties

Poly[(2-ethylhexyl acrylate)-ran-(tert-butyl acrylate)]-block-poly(2-cinnamoyloxyethyl acrylate) or P(EXA-r-tBA)-PCEA was synthesized by atom transfer radical polymerization. Reactivity ratios of EXA and tBA for copolymerization were determined. The specific refractive index increments of six diblocks were measured as a function of their composition. The diblocks were thermally stable and formed micelles in an automobile engine oil. Such micelles may be useful as an anti-friction additive in lubricating oils.     

Properties and morphologies of PVC/nylon terpolymer blends

A new kind of blends of polyvinyl chloride (PVC)/nylon terpolymer was reported in this article. Two compatibilizers were used in this study: one is a terpolymer of ethylene–n‐butyl acrylate–monoxide (EnBACO); the other is terpolymer of EnBACO grafted with maleic anhydride (EnBACO‐g‐MAH). The observation of scanning electron microscope (SEM) reveals that the PVC/nylon terpolymer blends have a two‐phase structure; and the nylon terpolymer phase is the continuous phase, and PVC domains in the PVC/nylon terpolymer/EnBACO‐g‐MAH blends have fine dispersion over a broad range of the PVC/nylon terpolymer ratio. EnBACO‐g‐MAH is more compatible with the nylon terpolymer than EnBACO. EnBACO and EnBACO‐g‐MAH have different effects on the glass transition temperatures of the PVC phase and nylon terpolymer phase in the blends. The notched Izod impact strength, tensile strength, elongation at break, Vicat softening temperature (VST), and melt flow index (MFI) critically depend on PVC/nylon terpolymer ratio, the kinds and concentration of the compatibilizers. The PVC/nylon terpolymer/EnBACO‐g‐MAH blends display a good combination of high toughness, high flowability, and high VST under low load. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 2823–2832, 2001     

Specific refractive index increments of Guayule rubber in several solvents

The specific refractive index increments of Guayule rubber were determined in four solvents (hexane, chloroform, toluene and tetrahydrofuran) using two wavelengths (5461 and 4360 Å). The determinations took place at 25°C and the results were compared with those obtained in natural Hevea rubber and Natsyn. The values of υ obtained were Hevea > Guayule > Natsyn.     

Some properties of poly(carbonates) and poly(thiocarbonates) from diphenols with methyl groups in the 3-position in the phenyl rings

Glass transition temperatures and the corresponding activation energies of poly(carbonates) and poly(thiocarbonates) with different side-chain substituents obtained from diphenols with methyl groups in the 3-position in the phenyl rings have been determined by differential scanning calorimetry at several scanning speeds. Partial specific volume and specific refractive index increments have also been obtained by densimetry and refractometry measurements in benzene at 25°C. The effect of the different substituents on these properties has been analysed. © 1998 SCI.     

ABS／PC／MMA类共聚物Q三元共混体系的性能和形态

本文研究了ABS/PC甲基丙烯酸甲酯(MMA)共聚物Q三元共混物的性能与Q含量的关系,对不同Q含量下共混物的拉伸、冲击、弯曲、耐热、熔体指数等性能进行了测试,并用扫描电镜观察了该三元共混物的形态。结果表明,加入共聚物Q可增加共混体系的相容性,在适当组成下可使共混物的弯曲强度提高到原来的1.7倍,同时其他力学性能有所提高或不受损失;共混物的熔体指数能符合工业生产要求。从经济角度看,Q价格也较低。因而ABS/PC/Q三元共混物可望开发为具有重要实际意义的塑料合金。     

Radiation effects of low refractive index,fluorinated methacrylate polymers for fiber cladding

The gamma radiation stability, optical properties, and mechanical properties of 1H, 1H, 3H-hexafluorobutyl and 1H, 1H-heptafluorobutyl methacrylate homopolymers and copolymers were determined and compared to poly(methyl methacrylate), PMMA. The aim of this study was to identify polymers for fiber cladding materials that exhibit improved optical radiation resistance and physical properties. Using ⁶⁰Co source, the samples absorbed 10 Mrads of gamma radiation at 0.04 Mrads/hr in an air environment. UV/Vis transmission spectra were obtained before irradiation, just after 10 Mrads, and regularly thereafter, to track recovery in transmittance. The glass transition temperatures, decomposition temperatures, refractive indices and flexural moduli were also obtained. Poly(heptafluorobutyl methacrylate) exhibited the greatest resistance to radiation induced discoloration and the lowest refractive index of the compositions tested. As the composition of the copolymers increased in hexafluorobutyl methacrylate concentration, both the radiation induced discoloration and the refractive index increased.     

High-refractive quinolinone-based polymers for ophthalmic devices

Seven novel high refractive index (HRI) acrylic monomers, comprising the quinolinone structural motive, have been synthesized and characterized. Cross-linked homo- as well as copolymers were prepared by photochemical bulk polymerization. The homopolymers show refractive indices at 589 nm (n ₅₈₉) ranging from 1.60 up to 1.68, glass transition temperatures (T _g) from 52 to 76 °C, and Abbe numbers (ν _Abbe) of 19 to 25. Due to these parameters, the homopolymers are not suitable to be used directly for intraocular lens (IOL) manufacture, but the quinolinone monomers may be used as high refractive index components in copolymers. Potential mixtures were calculated theoretically and one example, a copolymer with PEA and PEGPEA, was prepared and characterized. The experimentally found values were T _g?=?24 °C, n ₅₈₉?=?1.593, and ν _Abbe?=?28.3. Interestingly, the quinolinone compound which does not have any spacer between the polymerizable group and the high refractive index group appears to be the most useful one. The lightfastness of the new material fulfills the demands for IOLs. Quinolinone derivatives are promising new comonomers for high refractive index copolymers.     

Formation and anisotropic properties of ion-exchanged KTiOPO4 crystal waveguides

Z-cut KTP crystal waveguides have been fabricated in Ba(NO₃)₂/RbNO₃ bath using ion-exchange process. The effective mode indexes for the TE and TM polarizations are measured by the prism coupling method at the wavelengths of 488, 501.7, 514.5, 532, 632.8 and 1064nm respectively. The refractive index profiles are then determined by the inverse WKB method, which are shown to be accurately modelled by the complementary error function. Surface refractive index increments are computed and shown to be anisotropic. The diffusion coefficient of Rb⁺ in KTP is determined and the formation mechanisms of the waveguide are discussed.     

Specific refractive index increments of ethylene–vinyl acetate copolymers in trichlorobenzene solutions at 145°C

Specific refractive index increments of ethylene/vinyl acetate copolymers have been masured in trichlorobenzene at 145°C. A relationship between these values and copolymer composition has been determined for use in light scattering measurements of weight-average molecular weights of these materials. The data are also required for analysis of molecular weight distributions by size exclusion chromatography with light scattering detection.     

HPM/St/MA三元共聚物的合成及其热分解动力学

采用溶液聚合法制备了N-(4-羟基苯基)马来酰亚胺/苯乙烯/马来酸酐三元共聚物,通过红外光谱对其结构进行了表征,并利用TG和DTG技术对该共聚物的热性能和热分解动力学进行了研究。结果表明,由Fly-nn-Wall-Ozawa法求得三元共聚物的热分解表观活化能为147.38 kJ,指前因子为2.62×1010;Crane法求得的反应级数为0.95。该共聚物热分解受单机理控制,初始热分解温度为660 K,最大热分解温度为707 K,在740 K时热分解基本结束,较二元共聚物St/MA其耐热性明显提高。     

A molded deep-UV portable conformable masking system

A second-generation capped deep-UV portable conformable masking system Is described. Two major improvements of this system are; (1) The replacement of the PMMA bottom layer with the PMMA-MA-MAN terpolymer which has a higher thermal stability and a higher deep-UV sensitivity. (2) The application of the mold hardening process to eliminate the “wings” protruding from the novolac-terpolymer interface, to facilitate a better choice of developers for the bottom layer, and to provide a better refractive index match between the novolac image lines.     

Characterization of styrene-butadiene copolymers by light scattering

The general theory of Stockmayer and Benoit and their coworkers yields the weight average molecular weight of a binary copolymer and parameters which reflect the heterogeneity of chemical composition of the copolymer, using light scattering data from solutions in at least three solvents with different refractive indices. Although this theory has been applied successfully to block and graft copolymers and to mixtures of homopolymers, it has not seemed to be valid for random copolymers.In this report, molecular weight and heterogeneity parameters of a number of gel-free styrene-butadiene emulsion copolymers were estimated from results of light scattering measurements in toluene, cyclohexane and 1,2-dichloroethane. The calculated heterogeneity parameters contradict expectations from copolymerization theory and appear to be in error. It is suggested that the particular difficulties with statistical copolymers result from a dependence of specific refractive index increment on polymer molecular weight. This dependence varies with different solvents. The effect is illustrated by experimental results for polystyrenes in toluene, cyclohexane and 1,2-dichloroethane. Accurate study of copolymer characteristics requires selection of solvents such that the differences between specific refractive indices of the appropriate homopolymer solutions do not depend strongly on polymer molecular weight in the molecular weight range which corresponds to the sum of homopolymer sequences in the particular copolymers. The apparent inapplicability of the theory to random copolymers appears to be an artifact of the particular systems which were studied.