D L Brydon

Fibres from polypropylene and liquid crystal polymer (LCP) blends: 1. Effect of LCP concentration

Abstract Polypropylene (PP) resin and a thermotropic liquid crystal polymer (LCP) were mixed and coextruded on a screw extruder. The LCP was found to exist in fibril form above a PP/LCP (wt/wt) ratio of 100 5 and a PP/LCP ratio of 100 15 the LCP existed in a network structure. For the as-spun fibre, both the initial modulus and the yield stress increased with the increase in the LCP concentration. In the drawn fibres, however, the LCP fibrils were found to be split into short fragments. A two-stage drawing process was used in order to reduce the extent of fracture of the LCP fibrils. The drawn fibres were found to contain more long fibrils from the two-stage process and as a result, there were significant increases in both the tensile strength and initial modulus of the two-stage drawn fibres.

Fibres from polypropylene and liquid-crystal polymer blends using compatibilizing agents: 1. Assessment of functional and non-functional polypropylene—acrylic acid compatibilizers

Abstract A graft polymer based upon acrylic acid-functionalized polypropylene (PP-AA) and PP-AA itself were assessed as compatibilizers for polypropylene/liquid-crystal polymer (PP/LCP) polyblend fibres. It was found that the functional compatibilizer improved interfacial adhesion and thus fibre properties, depending on the type of hot-drawing process used, as well as significantly enhancing the thermal stability of the fibre. Incorporation of PP—AA increased fibre crystallinity and orientation, with a slight enhancement of fibre properties observed. This was attributed to the promotion of specific polar interactions between the blend components.

Fibres from polypropylene and liquid crystal polymer blends: 3. A comparison of polyblend fibres containing Vectra A900, Vectra B950 and Rodrun LC3000

Abstract Polyblend fibres were made of polypropylene (PP) and three thermotropic liquid crystal polymers (LCPs). The LCPs were found to exist in different morphological structures; the Vectra A900 and Vectra B950 LCPs existed mainly as fibrils, while the Rodrun LC3000 existed as short elongated ribbons. The tensile properties of the as-spun fibres were improved on addition of the LCPs, with the properties of the drawn polyblend fibres varying with the drawing procedure. In one-stage drawing, the polyblend fibres gave poorer tensile properties than the pure PP fibre. However in two-stage drawing, the Vectra A900 blend showed an increase in initial modulus over that of the pure PP fibre, while the Rodrun LC3000 blend produced an improvement in fibre tenacity.

Fibres from polypropylene and liquid crystal polymer blends using compatibilizing agents: 3. Assessment of graft side chain liquid crystalline compatibilizers based upon acrylic acid-functionalized polypropylene

Graft side-chain liquid crystalline functional copolymers based upon acrylic acid-functionalized polypropylene (PP-AA) were assessed as compatibilizers for polypropylene/liquid crystalline polymer (LCP) polyblend fibres. The compatibilization effect observed was found to be dependent upon the liquid crystalline phase temperature range of the compatibilizer, with the most favourable being in a liquid crystalline state during fibre melt extrusion and hot drawing, thus contributing a lubricating effect to the blend and giving enhanced physical properties as a result.

Separation and determination of oligomers and homologues of aliphatic alcohol ethoxylates in textile lubricants and lubricant emulsion by high-performance liquid chromatography

Abstract Homologous mixtures of 3,5-dinitrobenzenoates of aliphatic alcohol ethoxylates (AEs) were separated by high-performance liquid chromatography (HPLC) with high resolution using an amino bonded silica column and gradient elution of ternary solvents (hexane-dichloromethane-methanol). When the method was combined with novel sample clean-up and extraction procedures, oligomers of AEs in textile lubricants and a lubricant emulsion were satisfactorily determined with recoveries 75% and good reproducibility. A reversed-phase HPLC method was also developed to characterise the alkyl groups of AEs.

Fibres from polypropylene and liquid crystal polymer blends: 2. Effect of extrusion and drawing conditions

Abstract The drawing conditions were studied for a polyblend fibre of polypropylene (PP) and a thermotropic liquid crystal polymer (LCP). It was found that, in one-stage drawing, the LCP fibrils were split into short fragments with aspect ratios of around 10. Although fibre properties were improved with the increase in drawing temperature, the best properties of the polyblend fibre from one-stage drawing were poorer than those of the pure polypropylene fibre. A two-stage drawing process was studied in terms of the ratios and temperatures of the first- and second-stage drawings. It was found that the fibre properties were strongly affected by these parameters. At best, the fibre tenacity and initial modulus in the two-stage drawing were 14% and 39% higher than the highest values from the one-stage drawing. The LCP fibrils were found to split to a much lower extent in the two-stage drawing. The optimum drawing proceedure was applied to a series of polyblend fibres extruded under various extrusion rates and with a number of draw-down ratios.

Separation of broadly distributed nonylphenol ethoxylates and determination of ethylene oxide oligomers in textile lubricants and emulsions by high-performance liquid chromatography

A simple and rapid high-performance liquid chromatography method is described for separation and determination of ethoxylated nonylphenols. By using an amino bonded silica column with an acetonitrile-water gradient, the oligomers of ethoxylated nonylphenols with an average of 6 EO (ethylene oxide number) up to 40 EO were separated with satisfactory resolution. It was found that the partition of solutes between the stationary and mobile phases, and hydrogen bonding between solutes, solid-phase amino groups, water and acetonitrile were the main factors governing separation. The recoveries of total oligomers of nonylphenol-8 EO from a mixed emulsion with mineral oil, methyl oleate, peanut oil and the textile lubricant Blend 1 were 90.0±10.2, 95.6±7.9, 90.0±9.5 and 107.2±11.4%, respectively. The application of this method can be extended to determine non-ionic surfactants in other matrices.

Production of thermally stable polypropylene fibers

Polypropylene (PP) fibers were made with a number of different processing conditions, such as one-stage drawing, two-stage drawing, and a combination of drawing, annealing, and relaxation. The thermal stability of these fibers in terms of shrinkage in length at 100, 130, and 150°C was studied. It was found that the thermal shrinkage can be greatly improved with multi-stage drawing and with annealing. The fibers that were two-stage-drawn, relaxed, and then annealed remained stable at 130°C while still having a fiber tenacity in excess of 0.8 N/tex. Thermal stability at 150°C was more difficult to improve. However, the fibers that were drawn in three stages with a final drawing temperature of 185°C showed thermal shrinkage at 150°C of less than 10%. Finally, it was found that the thermal shrinkage of PP fibers at 150°C can be greatly reduced by blending a minor component of a liquid crystal polymer into the PP fibers. With two-stage drawing and annealing, fibers with shrinkage at 150°C of only 2.9% were produced.