Printing flax/polyester blends—a new approach

Work at the University of Ulster has been carried out to investigate methods of achieving startling print colour effects. It has been realised that by arranging fibre blends and distribution, pleasing aesthetic results are made possible. In this article Brian Hill and George Gray give a brief account of their research.     

Study of unsaturated polyester and vinylester morphologies using excimer laser surface treatment

A technique based on the use of an ArF excimer laser (193 nm) to analyze the morphology of the unsaturated polyester and vinylester networks has been developed. This method is based on the use of the differences between the thresholds at which ablation of the various constituent phases of the materials occurs. After having determined the ablation threshold of a polystyrene, various surface treatments using excimer lasers fluence around this threshold were applied to unsaturated polyesters and vinylester. In the latter case, a two-phase structure consisting of microgels in a polystyrene phase was shown by scanning electron microscopy observations, allowing us to conclude that the mechanisms by which vinylester and unsaturated polyester networks are formed are similar. We also observed that the two-phase structure of the vinylester matrixes, unlike that of the unsaturated polyesters, is organized rather than random-structured, which could represent a major parameter contributing to the very good hydrolysis stability of these materials. In the event of degradation by osmotic mechanisms, the organized structure network would enable limiting of the development of the osmotic pressures by distributing the forces within the material, thus avoiding crazing. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 66: 1703–1714, 1997     

The printing of polyester/cellulose blends-a new approach

This paper introduces a new dye system for the printing of polyester/cellulose blends. The new system is based on a combination of disperse dyes containing diester groups and reactive dyes containing a monochloro-s-triazinyl reactive group. By reference to published work on the reaction mechanism of monochloro-s-triazinyl reactive dyes with cellulose the development of a new approach to bring about reactive dye fixation in essentially neutral pH conditions is discussed. Practical application details of the new dye system are emphasised.     

灯箱布用涤纶工业丝纺丝工艺研究

利用正交试验和单因子试验,对影响灯箱布用涤纶工业丝的断裂强度和干热收缩率指标的工艺因素进行了研究。优化了灯箱布用工业丝的纺丝工艺,物理指标满足灯箱布使用要求。     

Afterclearing by ozonation: a novel approach for disperse dyeing of polyester

A set of trials has been conducted to examine the efficiency of ozonation afterclearing on poly(ethylene terephthalate) fibres dyed with disperse dyes. The afterclearing process was performed in neutral distilled water at room temperature with 12.8 ± 0.3 mg/min ozone at 400 ml/min ozone gas flow rate. The results indicate that 1 min ozonation time is adequate to achieve wash fastness results comparable with conventional reduction clearing without significant colour yield losses. Ozonation periods greater than 1 min not only caused significant colour yield losses, but also caused a severe decrease of the breaking load of the fabric. The advantages of ozonation afterclearing are: savings in energy and time, as it is performed at room temperature for only 1 min, and decrease of environmental load as it avoids the use of the harsh chemicals used in conventional reduction clearing.     

Compatibility and physical properties of a new polyester blend

The compatible nature of a new polyester blend, polybutylene-terephthalate (PBT) and a copolyester of bisphenol-A-neopentyl glycol-terephthalate (CP-350), has been inferred from the single T_g by DSC and dynamic mechanical studies. Compatibility is further confirmed from the progressive melting point depression of PBT, and the increasingly coarse and open spherulitic morphology of the blends as the weight percent of CP-350 increases. At and above 40 weight percent of CP-350, crystallization of PBT is impeded by the presence of high concentrations of CP-350 which results in a low degree of PBT crystallinity (0-8 percent) in such blends. The melt viscosity as a function of blend composition shows a good fit to the Hayashida model.     

A new two-stage curing system: Thiol-ene/epoxy homopolymerization using an allyl terminated hyperbranched polyester as reactive modifier

An allyl terminated hyperbranched polyester (HBP) was added to an epoxy formulation containing a trithiol compound to perform a thiol-ene click reaction. By this procedure a flexible thioether network was formed. The photoirradiation of the reactive mixture, which contained a cationic photoinitiator, converted the thioether network in a multifunctional thermal macroinitiator, capable to initiate the cure of the cycloaliphatic epoxy resin(CE) in a second thermal stage. Depending on the proportion of HBP, thermal or photocuring of the epoxy resin took place in different extent, leading to networks with different structures. The photocuring procedure was followed by FTIR and the thermal second stage by DSC. The materials obtained were characterized by DMTA, TGA and SEM. The addition of HBP-Allyl and the trithiol to the formulation allowed increasing the T_g on comparison with the neat epoxy thermoset. The system proposed constitutes a new two-stage dual photo-thermal curing procedure for cycloaliphatic epoxy resins with a thermal latent character.     

合成不饱和聚酯树脂的新型催化剂

介绍用自制催化剂合成通用型不饱和聚酯树脂的新工艺,克服了传统工艺的缺点,使反应速度加快,树脂质量提高,讨论了该催化剂存在下,工艺条件对反应的影响,给出了适宜的催化剂用量。     

Three-element mixed oxides: a new approach to basic catalysts

A series of three-element mixed oxides (IA)_x(IIA)_yAlO_z was prepared by sol–gel method, adopting a multivariate experimental design strategy in order to explore in a rational way the effects of preparation parameters on textural and basic properties. The textural properties were determined from N₂ adsorption/desorption isotherms, the basicity distribution by CO₂ chemisorption and temperature programmed desorption. Besides, the reactivity of toluene in the side-chain alkylation with methanol was taken as a measure of the acid–basic character of these oxides. The prepared three-element mixed oxides showed good basicity (>300 μmol/g) and textural properties among the mesoporous materials. Density and strength of the basic sites of the materials were related to the synthesis parameters by applying the multivariate analysis to data modelling. For example, the presence of large amount of alkali metals, IA/Al=0.30, was related to the increased density of medium-strong basic sites. The product distribution of the model reaction confirmed the presence of weak and very strong basic sites, the former responsible of aromatic ring alkylation and the latter of styrene synthesis.     

A new approach to batch process optimization using experimental design

Empirical and mechanistic experimental design methods are combined to construct partial models, which are, thus, used to design a process. The grid algorithm restricts the next experimental point to potential process optima, according to the confidence intervals around the optimal points, and works with any experimental design algorithm such as D‐optimal. Two case studies show the advantages of implementing the grid algorithm. On average the improvement due to the grid algorithm was 15–20% in the first case study. The second case study is based on thin film growth using four potential models, with the most probable model used for experimental design. The grid algorithm balances the trade‐off between two extremes: D‐optimal designs and sampling at the predicted optimal point. The methodology presented shows that the experimenter does not have to decide ahead of time on purely empirical or mechanistic experimental design methods, since both may be useful. © 2008 American Institute of Chemical Engineers AIChE J, 2009     

Dielectric spectroscopy using dielectric probes: a new approach to study glass transition dynamics in immiscible apolar polymer blends

Dielectric relaxation spectroscopy using dielectric probes was applied to study the (glass transition) dynamics in binary blends of isotactic PP, PS and LDPE. The blends were prepared by melt-mixing and doped with 0.5% of the dielectric probe 4,4′-(N,N-dibutylamino)-(E)-nitrostilbene (DBANS) (van den Berg O, Sengers WGF, Jager WF, Picken SJ, Wübbenhorst M. Macromolecules 2004;37:2460. [17]). Due to the selective amplification of the dielectric relaxation processes related to the dynamic glass transition of the polymers, accurate relaxation data were obtained, even for the minor phases. No substantial influence of the blend composition and the blend morphology on the glass transition dynamics was found, indicating that both blend constituents behave like homogeneous bulk materials. The normalised relaxation strength of glass transition processes remained constant, regardless of the blend type and blend composition. This indicates that the probe molecule, DBANS, was equally distributed over the two blend components in all three polymer combinations PE-PP, PE-PS and PP-PS.     

A new approach for patterning epiclon-based polyimide precursor films using a lyotropic liquid crystal template

Blends of hydroxypropyl cellulose (HPC) in lyotropic phase have been prepared with a new epiclon-based poly(amic acid) (PAA) in different ratios. The detailed surface morphology of the PAA/HPC films was examined by polarized light microscopy (PLM) and atomic force microscopy (AFM). Besides the specific interactions, such as the hydrogen bonds between PAA and the liquid crystalline component, a slight cross-linking produced in the PAA structure by UV irradiation stabilized the resulting morphology. The effect of UV exposure and the influence of the HPC component weight ratio on the morphology developed by the PAA/HPC blends were investigated. The band texture, typical for lyotropic HPC solutions, evidencing different intensities and dimensions, is observed from atomic force microscopy images in PAA/HPC, being distinguished even at high PAA content and is also maintained after HPC removal with a selective solvent, namely acetone. These results lie at the basis of future investigations concerning high performance mixed alignment layers used in display devices or cell culture substrates with tuned morphology.     

Metal deposition onto a thiol-covered gold surface: A new approach

In this study, we report on details of a new technique for depositing metal on top of a self-assembled monolayer (SAM). The experiments were performed with 4,4′-dithiodipyridine (4-PySSPy) SAMs on Au(1 1 1) electrodes, which were immersed without potential control into a Pd(II)-containing solution, where Pd(II) adsorbs on the surface by forming a complex with the pyridine nitrogen. The complexed Pd(II) ions were reduced electrochemically to Pd(0) after transferring the electrode to a Pd ion-free solution. Upon reduction, monoatomic high Pd islands were observed in STM. From cyclic voltammetry, in situ STM and ex situ angle-resolved XPS we conclude that these islands reside on top of the SAM, not underneath. It is shown that palladium complexation and deposition on self-assembled monolayers of 2-mercaptopyridine is not possible.     

A new development of the strain energy function for hyperelastic materials using a logarithmic strain approach

The development of a new strain energy function for hyperelastic solids based on the logarithmic strain measure is the objective of the present article. For all possible types of deformation it was shown that the proposed energy function is based on three independent material parameters. Using available experimental data for rubber‐like materials from the literature, one may determined the materials parameters by a nonlinear fitting. The available domain of the strain energy function can be determined by plotting the third invariant of logarithmic strain vs the second one. The numerical integration of the experimental data of true stress as a function of the logarithmic strain for various types of deformation yields the strain energy function W, for rubber‐like solids. The proposed model involves only one parameter that must be determined by fitting with the experimental data. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 660–672, 2000     

Polymer flame retardancy: A new approach

New types of ecologically friendly polymer flame-retardant systems were proposed for Nylon 6,6 and polypropylene [high temperature polymer–organic char former, poly(vinyl alcohol), and silicon–inorganic system]. These systems can act in condensed and gaseous phases. The cone calorimeter and LOI tests indicated the improvement of fire-retardant properties for compositions of flame retardants with Nylon 6,6 and polypropylene in comparison with pure polymers. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 68:715–725, 1998