Kim L. Pickering

Properties and Performance of Natural-Fibre Composites

Part 1 Natural-fibre composites: Natural fibres for composite applications: Types and properties Matrices for natural-fibre reinforced composites Engineering the fibre/matrix interface in natural-fibre composites Processing techniques for natural and wood-fibre composites Development of non-wood natural-fibre composites Cellulose nanocomposites. Part 2 Case studies and opportunities: Natural-fibre composites in the automotive sector Natural-fibre composites in structural applications Natural-fibre-biodegradable polymer composites for packaging Opportunities for using wood and biofibers for energy, chemical feedstocks and structural applications Market issues and considerations in development of natural/wood-fibre composites. Part 3 Performance of natural-fibre composites: Mechanical testing of natural-fibre composites Mechanical performance of thermoplastic matrix natural fibre composites Long-term performance of natural-fibre composites Modelling natural-fibre composites.

Study on the Mechanical Properties of Jute/Glass Fiber-reinforced Unsaturated Polyester Hybrid Composites: Effect of Surface Modification by Ultraviolet Radiation

Jute fiber (Hessian cloth) and E-glass fiber (mat)-reinforced, unsaturated polyester (USP) resin along with additives and initiator, composites are prepared by the hand layup technique at room temperature (25°C). Jute fiber content in the composites is optimized with the extent of mechanical properties, and composites with 25% jute show higher mechanical properties. The mechanical properties are found to increase with the incorporation of dissimilar portions of glass fiber into the jute fiber-reinforced composite. Among all the resulting hybrid composites, the composite with a jute to glass ratio of 1: 3 demonstrates improved mechanical properties, such as tensile strength (TS) 125%, tensile modulus (TM) 49%, bending strength (BS) 162%, and bending modulus (BM) 235% over untreated jute composite. To further improve the properties, the surface of jute and glass fiber is irradiated under UV radiation of different intensities. UV pretreated jute and glass fibers (1: 3) at optimum intensities show the highest mechanical properties, such as TS 70%, TM 33%, BS 40%, and BM 43% compared to untreated jute-and glass-based hybrid composites. UV-modified jute/glass-reinforced hybrid composites also show the best of Charpy impact strength (40 kJ/m2). The interfacial adhesion between jute/glass and USP is monitored by a scanning electronic microscope (SEM).

Weak link scaling analysis of high-strength carbon fibre

The strengths of polyacrylonitrile-based carbon fibres were obtained for lengths ranging from 1 to 500 mm. These were analysed according to the two-parameter Weibull distribution and the accuracy of using weak-link scaling was assessed. Extrapolation using weak link scaling over the orders of magnitude required for models of composite strength was found to give large errors, highlighting the inadequacies of the two parameter Weibull expression for modelling purposes.

Reengineering of a commercially available bovine intravaginal insert (CIDR insert) containing progesterone

The purpose of this study was to reengineer a commercially available intravaginal insert containing 1.9 g progesterone (CIDR intravaginal insert) for a 7-day insertion period in cattle. The reengineering process resulted in a reduced initial drug load (1.38 g) and a reduction in the residual drug load following insertion, while at the same time maintaining the biological performance of the insert. The in vitro and in vivo pharmaceutical properties of the commercially available CIDR intravaginal insert were characterized initially to gain a thorough understanding of the factors that affected progesterone release from the insert. The effect of changing a selection of formulation and physical variables of the insert was also investigated (including surface area, drug load, addition of pore forming materials, silicone shore hardness and drug particle size). The knowledge gained from these studies was used to define the characteristics of the reengineered insert which was then manufactured and shown to be bioequivalent and clinically equivalent to the commercially available insert.

Fiber Pretreatment and Its Effects on Wood Fiber Reinforced Polypropylene Composites

ABSTRACT This study investigates the effect of pretreatment of fiber with NaOH and coupling with maleated polypropylene (MAPP) on the physical and mechanical properties of composites, based on radiata pine (Pinus Radiata) fiber, produced with a polypropylene matrix, using a twin-screw extruder followed by injection molding. Prior to reinforcement, the fiber was treated with NaOH. The effect of treatment was assessed using zeta potential, scanning electron microscopy (SEM), and X-ray diffraction (XRD). Tensile testing, SEM, differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA) were carried out to assess the effect of modification on composite properties. An increase of 106% for strength and 302% for Youngs modulus were obtained by using 60 wt% fiber and 2 wt% MAPP, compared to the unreinforced matrix. Fiber pretreatment with NaOH reduced strength but improved Youngs modulus (370% compared to unreinforced matrix) of resulted composite.

Development of an injection molded poly(ϵ-caprolactone) intravaginal insert for the delivery of progesterone to cattle

Abstract This paper reports experiments conducted to research, develop and clinically evaluate an injection molded intravaginal insert manufactured from the biodegradable polyester poly(ϵ-caprolactone). The study demonstrated that it is possible to engineer poly(ϵ-caprolactone) into a shape that is well retained, and can be used as a platform for the controlled delivery of progesterone via the vagina of cows. Field evaluation showed that the poly(ϵ-caprolactone) intravaginal inserts containing 10% (w/w) progesterone were at least as effective clinically as the commercially available CIDR intravaginal insert.

The effect of poly[methylene(polyphenyl isocyanate)] and maleated polypropylene coupling agents on New Zealand radiata pine fiber-polypropylene composites

The effects of poly[methylene (polyphenyl isocyanate)] (PMPPIC) and maleated polypropylene (MAPP) coupling agents, separately and combined, on the strength and Young’s modulus of New Zealand radiata pine-reinforced polypropylene (PP) composites were assessed. A modest improvement compared to the unreinforced matrix strength of 4% and much greater improvement of 123%, substantially greater than reported elsewhere in the literature, were obtained using PMPPIC and MAPP respectively. Young’s modulus improvements compared to the unreinforced matrix of 77 and 177% were obtained using PMPPIC and MAPP respectively. The MAPP coupling agents with the longest chain lengths and lower functionality gave the greatest benefit, supporting chain entanglement as the major mechanism for enhanced bonding with PP. Relatively high moulding temperatures and low injection pressures, bringing about enhancement of fiber orientation in the test direction, also appear to have contributed to such large improvements in composite properties in the current work. Combination of PMPPIC and MAPP coupling agents produced mixed results: benefits were obtained by combining PMPPIC and MAPP with the longest chain lengths which can be explained by PMPPIC bonding with hydroxyl groups not accessible to further coupling with MAPP once saturation is achieved.

Hemp Fibre Reinforced Poly(Lactic Acid) Composites

The potential of hemp fibre as a reinforcing material for Poly(lactic acid) (PLA) was investigated. Good interaction between hemp fibre and PLA resulted in increases of 100% for Young’s modulus and 30% for tensile strength of composites containing 30 wt% fibre. Different predictive ‘rule of mixtures’ models (e.g. Parallel, Series and Hirsch) were assessed regarding the dependence of tensile properties on fibre loading. Limited agreement with models was observed. Differential scanning calorimetry (DSC) and x-ray diffraction (XRD) studies showed that hemp fibre increased the degree of crystallinity in PLA composites.

Failure micromechanisms in continuous carbon-fibre/epoxy-resin composites

Abstract This study is concerned with the influence of the strength of the fibre/matrix interface on the strength and failure process in uniaxial arrays of carbon fibres in an epoxy resin. A batch of high-strength carbon fibres has been supplied with several levels of an oxidative surface treatment to produce composites with various interface strengths. Tensile tests have been conducted on single fibres, on loose bundles and on tows impregnated with an epoxy resin. Further tests have been conducted to estimate the interface strength. A hybrid-tow test configuration has then been used to follow the sequence of failure within a single tow of the carbon fibre in a uniaxial composite. The results indicate that the fibre strength is affected only slightly by the surface treatment, the strength of impregnated tows is reduced, and their mode of failure and that of the hybrid tows is affected significantly.

Analysis of mechanical properties of hemp fibre reinforced unsaturated polyester composites

Different chemically treated hemp fibre reinforced unsaturated polyester composites were investigated over a range of fibre content (0–60 wt%). Although Young’s modulus of all the short fibre reinforced unsaturated polyester composites was found to be higher than that of unreinforced unsaturated polyester; however, tensile strength of the composites exceeded that of the unsaturated polyester matrix only for the combined alkali- and silane-treated fibre composites at 40 wt% fibre content. The decrease in tensile strength of the composites could be attributed to stress concentrations caused by the fibres in conjunction with the brittle matrix. Impact strength of all the treated fibre composites was higher than that of the untreated fibre composites at all fibre contents. KIc and GIc of the composites decreased initially and then increased as the fibre content increased because more and more fibres being available to pull-out. The mechanical properties of the composites were increased further due to the alignment of long fibres.