BLACK POLYPROPYLENE MULCH TEXTILE IN ORGANIC AGRICULTURE

Black polyethylene mulch is used for weed control in a range of crops under the organic system. The use of black polypropylene mulch is usually restricted to perennial crops. The trial was conducted at Experimental station of Department of Crop Production of the Czech University of Life Science Prague-Uhříněves in Czech Republic. For the experiments were used black polypropylene woven mulch (comparison wit bare soil), two varieties of early potatoes Finka and Katka. Black polypropylene textile was used in potatoes by organic agriculture and it had positive effect on soil temperature (in the depth of 100 mm). Slightly higher soil temperatures under black polypropylene mulch in the vegetation period after planting had favourable influence on earlier stands emergence. The soil water potential (in the depth of 250 mm) and also the soil water content have been beneficial for black polypropylene mulch. Significantly lower values of the soil water potentials have been found in the period after planting and at the end of vegetation. Black polypropylene mulch provided favourable temperatures and soil moisture. Post harvest analyses were focused on the determination of the yield and quality tubers from each variant

Cigarette filter material and polypropylene fibres in concrete to control drying shrinkage

Due to a reduction in demand for cigarette filter material (North East UK), significant quantities have arisen that have little commercial value. The filter manufacturers have been looking for another outlet for their product and polypropylene fibre replacement in concrete was considered. The purpose of adding Type 1 polypropylene fibres (BS-EN14889) to concrete is to control plastic shrinkage and reduce bleeding. A paired comparison test was carried out to examine concrete cured under extreme conditions of heat and air flow. This micro climate would cause uneven drying due to surface evaporation and internal stresses within the concrete matrix and as a consequence of this instigate drying shrinkage cracking. Type 1 micro polypropylene fibres have known properties to control drying cracking and the performance of concrete with polypropylene fibres was compared against plain concrete and concrete with cigarette filter material. The findings showed that when cigarette filter material and Type 1 polypropylene fibres were compared together their performance was very similar and showed less drying shrinkage cracks than plain concrete

Post crack flexural toughness in steel fabric and fibre reinforced concrete beams

The purpose of the paper is to provide independent research and evaluate manufacturers’ claims that structural polypropylene fibres provide satisfactory crack control reinforcement and compare the test results from macro synthetic polypropylene fibres against steel fabric reinforced concrete, extensively used as a crack control medium in concrete ground bearing floor/hardstanding slabs where tensile forces are likely to occur. Three concrete beam types were produced, plain, steel reinforced and fibre reinforced, and a comparative study was undertaken of post crack flexural toughness. The procedure used was to manufacture steel A 142 fabric and macro fibre reinforced concrete beams to provide load, deflection data, toughness indices and was compliant with, ASTM C1018 -97, [ASTM, 1997] using a three point loading arrangement. The data was representative of what might occur in a floor slab. The findings of the paper is that A1 42 steel fabric reinforcement as used in slabs was more effective in producing toughness and residual strength when directly compared to the performance of structural polypropylene fibre reinforced concrete. When small post crack forces are encountered within the concrete matrix, polypropylene macro fibres are suitable for crack control. The paper makes direct comparisons between known and widely used crack control using steel fabric, and the use of low modulus polypropylene macro synthetic fibres as a crack control medium

Low temperature thermal expansivities of polyethylene, polypropylene and their mixtures

Low temperature measurements of length- temperature curves of polyethylene, polypropylene, mixtures of polyethylene and polypropylene, and copolymer

Polypropylene Mesh Implant and A-prf Membrane for Reconstruction of the Traumatic Defects of the Lateral and Back Wall of the Maxillary Sinus

. Background: The aim of this study was to investigate the possible use of Polypropylene mesh implant and A-PRF membrane for covering the defects of the lateral and back wall of the maxillary sinus after its traumatic damages.Materials: non-resorbable Polypropylene mesh implant was used in 10 patients as a barrier membrane for prevention of adipose tissue herniation into maxillary sinus.Method: 3 D CT was used for assessment of bone fragments position and volumetric parameters of the maxillary sinus before and after surgical repair.Result: Postoperative 3-D CT after 2 months demonstrated effective reestablishment of anatomical configuration of sinus and its volume, absence of pathological inflammatory changes of the sinus mucosa.Conclusion: Polypropylene mesh implant provides effective barrier between soft tissues and maxillary sinus, due to its strength characteristic and biocompatibility

Development and characterisation of injection moulded, all-polypropylene composites

In this work, all-polypropylene composites (all-PP composites) were manufactured by injection moulding. Prior to injection moulding, pre-impregnated pellets were prepared by a three-step process (filament winding, compression moulding and pelletizing). A highly oriented polypropylene multifilament was used as the reinforcement material, and a random polypropylene copolymer (with ethylene) was used as the matrix material. Plaque specimens were injection moulded from the pellets with either a film gate or a fan gate. The compression moulded sheets and injection moulding plaques were characterised by shrinkage tests, static tensile tests, dynamic mechanical analysis and falling weight impact tests; the fibre distribution and fibre/matrix adhesion were analysed with light microscopy and scanning electron microscopy. The results showed that with increasing fibre content, both the yield stress and the perforation energy significantly increased. Of the two types of gates used, the fan gate caused the mechanical properties of the plaque specimens to become more homogeneous (i.e., the differences in behaviour parallel and perpendicular to the flow direction became negligible)

Polypropylene fibres within concrete with regard to heat induced spalling and reduction in compressive strength

The paper examines the effect of various polypropylene fibre additions (Types 1 and 2 and different fibre volumes) to concrete with regard to explosive spalling when subject to high temperatures similar to that experienced in building or tunnel fires. The pilot study used to determine an appropriate heat source for the test showed concrete to be a significant insulator and fire protection for structural members. Explosive spalling was shown to be reduced with the use of polypropylene fibres but the final compressive strength of concrete was significantly reduced and had little residual structural value after a 2 hour period of heating

Elaboration and study of the thermo-mechanical properties of an aligned cnt - polypropylene nanocomposite by twin-screw mixer

This study presents first the fabrication of a nanocomposite material based on Multi-Walled Carbon Nanotubes, and on a thermoplastic polymer matrix. First, a twin-screw mixer had been employed for preparing polypropylene nanocomposites loaded at 0.1, 1, 2, and 5wt% of MWCNT. Second, a characterization of rheological behavior for polypropylene as well as polypropylene/multi-walled carbon nanotube mixtures, at three temperatures (180, 200, and 220 °C,) has been carried out using cone and plate rheometer. Then, its thermomechanical properties have been studied. The work demonstrates how the addition of functionalized CNTs to a polypropylene will allow it to act as thermal conductor rather than as insulator

Interfaces and interfacial effects in glass reinforced thermoplastics - Keynote Presentation

Optimization of the fibre-matrix interphase region is critical to achieving the required performance level in thermoplastic matrix composites. Due to its initial location on the fibre surface, the sizing layer is an important component in the formation and properties of the composite interphase. Consequently, any attempt to understand the science of the composite interphase must encompass an understanding of the science of sizing. In this paper the role of sizings from fibre manufacture through to performance of composite parts is reviewed. In particular the role of organosilane coupling agents and how the formation of a polysiloxane interphase is influenced by the surface properties of the fibre is examined. The influence of the sizing film former in terms of its level of interaction with the silane coupling agent is also examined. The importance of residual stresses in thermoplastic composites in the values obtained for the apparent adhesion levels in these systems is highlighted. These residual stresses are shown to play a significant role in determining the level of interfacial strength in thermoplastic composites and in particular in polyolefin matrices. By applying some of the available models for this phenomenon this analysis is extended to explore the effect of the anisotropic fibre microstructure of carbon, aramid and natural fibres on the apparent interfacial strength in thermoplastic composites