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The effect of changing injection temperature on some mechanical and morphological properties for polypropylene material (PP)

Abstract

This is a study of a medical injection factory-Babylon carried out in order to achieve proper mechanical and morphological properties, PP has been injection molded by using cold runner injection molding machine with temperature variation (198, 200, 203……220°C) for ten samples. The physical and mechanical properties of PP product were examined. It has been found that the Shore hardness decreases linearly with injection molding temperature increasing. The tensile strength has a similar behavior to the hardness. However, it has been found that the MIF (Melt Index Flow) rates increases with the increase of injection molding temperature. The density of PP has been found for both virgin PP and the samples, it has been found that the density decreases with increasing operation temperature. FTIR (Fourier Transmission Infrared) spectra were taken for both samples with high and low operation temperature. Besides the SEM (Scanning Electronic Microscopy) test shows the difference in the morphology of the product surface and the PP product at high and low operation temperature. Moreover, for all these properties, the PP product exhibits good mechanical properties (hardness, tensile strength, density) for the samples produced at temperature lower than 207°C. While the physical properties such as MIF improved with injection temperature increasing, additionally, the SEM images show that the sample produced in low temperature have surface damage.

Open access
Application of photochromic pigment in mass dyed polypropylene fibres intended for intelligent textiles

Abstract

At the present time, characterised by worsening environmental conditions, the protection of human organism against irreversible damage is necessary. Protective clothing on base of smart textiles represents the future in human clothing. In this article, the effect of photochromic pigments on spinnability, drawability and properties of pigmented polypropylene (PP) fibres is presented.

Mechanical properties (tenacity and elongation at break, Young’s modulus), thermo-mechanical properties and the factor of average orientation of fibres were evaluated and discussed. The obtained results indicate a possibility of fibres preparation with photochromic pigments.

Open access
Effect of Matrix Viscosity on Rheological and Microwave Properties of Polymer Nanocomposites with Multiwall Carbon Nanotubes

Abstract

Nanocomposites of multiwalled carbon nanotubes (MWCNTs) in epoxy resin and polypropylene (PP) are studied. The effect of matrix viscosity on the degree of dispersion of nanotubes is determined by rheological methods. Rheology and microwave properties are correlated to estimate the optimal limits of nanofiller content required for improving the performance of nanocomposites. Rheological percolation threshold is determined for both types nanocomposites, ϕp=0.27% for the epoxy/MWCNT and; ϕp=1.5% for the PP/MWCNT, as found critical for achieving a network structure of interacting nanotubes in the matrix polymer. Good electromagnetic shielding efficiency was obtained for nanocomposites at nanotube contents above the rheological percolation. Low viscosity matrix facilitates contacts between MWCNTs, resulting in appearance of electromagnetic shielding at very low percolation threshold.

Open access
Structure and tensile properties of polypropylene/carbon nanotubes composites prepared by melt extrusion

Abstract

Polypropylene/carbon nanotubes (PP/CNTs) nancomposites were prepared with a single screw extruder by adding maleic anhydride-grafted poplypropylene (PP-g-MAH) as compatibilizer to polypropylene (PP) with different amounts of carbon nanotubes (CNTs) in the range of 0.1–0.7 wt.%. Structure and morphology of the prepared samples were examined by Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), polarizing light microscopy (PLM) and X-ray diffraction (XRD). The results showed that PP spherulites decreased in size when CNTs were introduced into the polymer. Mechanical properties of the samples were also studied. Tensile tests showed that with increasing amount of CNTs the strain at break decreased whereas the Young’s modulus was improved of 16.41 % to 36.05 % and tensile strength of 36.67 % to 64.70 % compared to pristine PP. The SEM microphotographs showed that majority of the CNTs were dispersed individually and oriented along the shear flow direction.

Open access
The effects of PLA biodegradable and polypropylene nonwoven crop mulches on selected components of tomato grown in the field

ABSTRACT

The results of two years (2010-2011) of field studies using two types of nonwoven mulches (one biodegradable, polylactic acid PLA 54 g m-2, and traditional polypropylene PP 50 g m-2) on the yield and quality of tomato are presented. Seeds of tomato (‘Mundi’ F1) were sown in a greenhouse, in containers filled with perlite and sand, and then the plants at the cotyledon stage were replanted in multipot trays filled with substrate for vegetable plants. In the last week of May, seedlings were planted on mulches in the field at a spacing of 50 × 100 cm. The mulch was maintained throughout the growing season. A plot that remained unmulched served as the control. Tomatoes were harvested once a week. The fruits were evaluated for L-ascorbic acid, dry matter, soluble sugars and nitrate content. In 2011, the analysis of the plant material showed that the concentration of L-ascorbic acid was about 23% higher in the tomato fruits harvested from plants grown on biodegradable PLA 61 g m-2 mulch in comparison to the control. A similar effect was demonstrated for the soluble sugar concentration in 2011 for both types of nonwovens.

Open access
Effect of Newly Synthesized Polypropylene/Silver Nonwoven Fabric Dressing on Incisional Wound Healing in Rats

Abstract

AIM: The present work aimed to investigate the effect of the antimicrobial nano Ag/polypropylene (PP\Ag) dressing on incisional wound healing on the experimental level.

MATERIALS AND METHODS: Male albino rats were divided into, control, PP/Ag dressing, Silver Sulfadiazine (Ag-SD) cream, blank PP dressing and undressed groups. Animals were sacrificed after 5, 10 and 15 days of incisional wound event. RESULTS: Reduction was found in incision wound length in PP/Ag dressed rats, Ag-SD cream treated rats, and blank PP dressed rats after 5, 10 and 15 days compared to undressed rats. Skin of PP/Ag group showed less adverse histopathological changes, enhanced granulation tissue formation, enhanced angiogenesis, accelerated re-epithelialization and quick complete healing; compared to all other groups. Significant decrease in TGF-β level was recorded in PP\Ag and Ag- SD cream groups as compared to blank PP group on day 5. While, significant decrease in TGF-β level was detected in PP\Ag group when compared with undressed and blank PP groups on day 10. TGF-β showed significant in PP\Ag group as compared to undressed, Ag-SD cream and blank PP groups on day 15.

CONCLUSION: The present results suggest that PP/Ag dressing enhances, promotes and plays an important role in wound healing.

Open access
Static and Dynamic Responses of a Reinforced Concrete Beam Strengthened with Steel and Polypropylene Fibers

Abstract

This paper describes an experimental investigation on mono steel and polypropylene (PP) fiber-reinforced concrete beams. The main aim of this present study is to evaluate undamaged and damaged reinforced concrete (RC) beams incorporated with mono fibers such as steel and PP fibers under free-free constraints. In this experimental work, a total of nine RC beams were cast and analyzed in order to study the dynamic behavior as well as the static load behavior of steel fiber-reinforced concrete (SFRCs) and polypropylene fiber-reinforced concrete (PPFRCs). Damage to the SFRC and PPFRC beams was obtained by cracking the concrete for one of the beams in each set under four-point bending tests with different percentage variations of the damage levels such as 50%, 70% and 90% of the maximum ultimate load. The fundamental natural frequency and damping values obtained through the dynamic tests for the SFRC and PPFRC beams were compared with a control RC beam at each level of damage that had been acquired through static tests. The static experimental test results emphasize that the SFRC beam has attained a higher ultimate load compared with the control RC beam.

Open access
Thermal and thermo-catalytic degradation of polyolefins as a simple and efficient method of landfill clearing

Thermal and thermo-catalytic degradation of polyolefins as a simple and efficient method of landfill clearing

Thermal degradation of the low density polyethylene (LDPE), polypropylene (PP) and the municipal waste plastics was investigated. The thermo-catalytic degradation of LDPE and PP was studied in the presence of the following catalysts: four different types of montmorillonite: K5, K10, K20, K30 and - for comparison - zeolites (natural - clinoptilolite, YNa+ and YH+). Thermal analyses TG-DTA-MS of polymers and polymer-catalyst mixtures were carried out in an argon flow atmosphere in isothermal and dynamic conditions. The following order was found: in lowering the reaction temperature for LDPE degradation YH+ > mK5 > mK20 = mK30 >mK10 > NZ > YNa+; for PP degradation: mK20 > mK5 = mK30 >mK10 > YH+ > NZ > YNa+. The activity tests were carried out in a stainless steel batch reactor under atmospheric pressure in a wide temperature range of up to 410°C, and using the atmosphere of argon flow. The liquid products were analysed by the GC-MS method. The hydrocarbons in the liquid products from thermal degradation of polymers were broadly distributed in the carbon fractions of C8 to C26 - for LDPE and C6 to C31 for PP.

Open access
Flexural Performance of Engineered Cementitious Compositelayered Reinforced Concrete Beams

Abstract

This study focuses to develop a new hybrid Engineered Cementitious Composite (ECC) and assesses the performance of a new hybrid ECC based on the steel short random fiber reinforcement. This hybrid ECC aims to improve the tensile strength of cementitious material and enhance better flexural performance in an RC beam. In this study, four different mixes have been investigated. ECC with Poly Vinyl Alcohol (PVA) fiber and PolyPropylene (PP) fiber of 2.0% volume fraction are the two Mono fiber mixes; ECC mix with PVA fiber of 0.65% volume fraction hybridized with steel fiber of 1.35% volume fraction, PP fiber of 0.65% volume fraction hybridized with steel of 1.35% volume fraction are the two additional different hybrid mixes. The material properties of mono fiber ECC with 2.0 % of PVA is kept as the reference mix in this study. The hybridization with fibers has a notable achievement on the uniaxial tensile strength, compressive strength, Young’s modulus, and flexural behavior in ECC layered RC beams. From the results, it has been observed that the mix with PVA fiber of 0.65% volume fraction hybrid with steel fiber of 1.35% volume fraction exhibit improvements in tensile strength, flexural strength, and energy absorption. The PP fiber of 0.65% volume fraction hybridized with steel of 1.35% volume fraction mix has reasonable flexural performance and notable achievement in displacement ductility over the reference mix.

Open access
Changes in Physically-Chemical Parameters of Latvian Cranberries During Storage

Abstract

The main purpose of the present research was to investigate the changes in physical-chemical parameters of fresh Latvian cranberries during storage. Cranberry (′Steven′, ′Bergman′, ′Pilgrim′, ′Early Black′, and ′Ben Lear′) fruit were collected at a processing plant in Kurzeme region, Latvia, in the first part of October 2010. For the experiments, also wild cranberries were collected in the bogs of the same region and at the same time. The berries were rinsed with tap water for 3±1 min, then strained for 10±1 min (mainly for visual cleanness), and afterwards stored in closed non-perforated polypropylene (PP) boxes in air ambiance and in glass jars in a cold boiled-water ambiance at 3±1 °C. Quality parameters of the berries were tested each three months using standard methods: vitamin C content - by high-performance liquid chromatography (HPLC); organic acids - by HPLC; moisture - by oven-dry method; colour parameters - by device COLOR TEC PMC; pH - by potentiometric method; anthocyanin - by spectrophotometrical method; and phenolic compounds - by HPLC. The shelf life of cranberries packaged in closed PP boxes in air ambiance was six months, but of cranberries packaged in glass jars in water ambiance - 12 months. The research showed that differences in moisture content, pH value, colour intensity, and anthocyanin content among the cranberry cultivars under different ambient conditions during storage were not significant. During 12 months of cranberry storage in glass jars in water ambiance, the content of vitamin C decreased on average by 90%, organic acids - by 54%, and phenolic compounds - by 60%. During six-month storage in closed PP boxes in air ambiance, the content of vitamin C decreased on average by 99%, organic acids - by 30%, and phenolic compounds - by 34%.

Open access