Short polyethylene terephthalate fiber (PET) reinforced NBR rubber composites

Acrylonitrile-butadiene rubber (NBR) has been reinforced with different content of PET up to 25 phr. Vulcanization of prepared composites as will as the unreinforced ones have been induced by ionizing radiation of accelerated electron beam of varying dose up to 150 kGy. Evaluations of the vulcanized composites have been followed up through the measurement of mechanical, physical and thermal properties. Also, scanning electron microscope (SEM) was performed. Mechanical properties, namely tensile strength (TS) and hardness were found to increase with the increase of irradiation dose as well as the increase in the content of PET up to 25 phr. Also, elongation at break (ε _b) was found to decrease with the increase of irradiation dose; however, the decrease in ε_b is not consistence with the increase in fibers loading. Young’s modulus (E) and tensile modulus at 25% elongation (E25) were found to increase with the increase of irradiation dose and fiber loading up to 20 phr. Also, the volume fraction of swollen rubber increases as irradiation dose and/or fiber content increased; it was more influenced by irradiation rather than fiber loading. Anisotropic swelling increased with irradiation and fiber loading up to 20 phr. SEM photomicrograph showed that irradiation causes adhesion between PET fiber and NBR where less pulling out and less pitting on the surface were observed. The thermal properties of the composite irradiated at 100 kGy reveal that the activation energy (E _a) increases up to 10 phr fiber content. When the composite that contains 10 phr fiber irradiated at doses higher than100 kGy, Ea decreased.     

Effects of processing parameters on the filament fiber diameter of spunbonded nonwoven fabrics

The air drawing model of polymer in spunbonding is established. The air drawing model of polypropylene polymer in spunbonding is confirmed by the experimental results obtained with the help of our university's equipment. The predicted filament fiber diameter is in accordance with the experimental data. The effects of the process parameters on the filament fiber are investigated in this article. It is found that a lower polymer throughput rate, a higher polymer melt temperature, a higher primary air temperature, a higher air suction speed, a higher quench pressure, a higher venturi gap can all yield finer fiber, whereas the effect of the web basis weight is not significant. The results show great prospects for this research in the field of computer assisted design of spunbonding technology. POLYM. ENG. SCI., 47:510–515, 2007. © 2007 Society of Plastics Engineers.     

A soft computing approach to model the structure–property relations of nonwoven fabrics

A soft computing approach to model the structure–property relations of nonwoven fabrics for filtration use is developed. Because the number of samples is very limited, the artificial neural network model to be established must be a small‐scale one. Consequently, this soft computing approach includes two stages. In the first stage, the structural parameters are selected by using a ranking method, to find the most relevant parameters as the input variables to fit the small‐scale artificial neural network model. The first part of this method takes the human knowledge on the nonwoven products into account. The second part uses a data sensitivity criterion based on a distance method that analyzes the measured data of nonwoven properties. In the second stage, the artificial neural network model of the structure–property relations of nonwoven fabrics is established. The results show that the artificial neural network model yields accurate prediction and a reasonably good artificial neural network model can be achieved with relatively few data points by integrated with the input variable selecting method developed in this research. The results also show that there is great potential for this research in the field of computer‐assisted design in nonwoven technology. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 442–450, 2007     

A physical‐mathematical model for the dispersion process in continuous mixers

To modify the properties of polymers, mineral fillers are frequently added during the compounding process. Because of adhesive forces, these pulverized fillers tend to agglomerate. Therefore, in order to achieve good homogenization, it is essential not only to distribute them but also to break down the solid agglomerates. A number of relating models have been published, describing observations (agglomerate rupture, erosion, clustering) made during the dispersion process in a mostly isolated manner. New models for each observed effect have been developed and later superimposed in order to get a comprehensive model of the dispersion process. To verify the model, it was implemented into a program for the process simulation of co‐rotating twin‐screw extruders. It was then compared to experimental data. The results showed that the model is able to describe the experimentally determined data.     

Carbon nanotube surface-induced crystallization of polyethylene terephthalate (PET)

The crystallization of polyethylene terephthalate (PET) and its effect on the electrical behavior of nanocomposites of PET and carbon nanotubes (CNTs) was studied. A series of nanocomposites composed of polyethylene terephthalate/carbon nanotubes (PET/CNTs) containing 0, 1 and 2% wt/wt carbon nanotubes were prepared by melt extrusion. The morphology developed by the nanocomposites during non-isothermal crystallization at different cooling rates was evaluated using various experimental techniques. Thermal analysis showed an increase in the crystallization temperature of the nanocomposites, which was associated with the nucleation ability of the CNTs, and confined growth that resulted in a 3D-to-1D reduction in the crystallite geometry of the nanocomposites. X-ray diffraction indicated that the crystal structure of the nanocomposites was not affected by the presence of carbon nanotubes or the cooling rate. However, the crystallinity of PET and the nanocomposites increased as the cooling rate decreased. The electrical conductivity of the materials as a function of the cooling rate, at a constant CNT content, showed a marked (two orders of magnitude) increase in passing from the amorphous state to the crystalline state. The results of theoretical calculations indicated self-assembly between the surface of the nanotubes and the aromatic ring of PET; it was proposed that the stacking of aromatic rings on the surface of the nanotubes has an effect on the rearrangement of electric charge.     

Mechanical properties of recycled kenaf/polyethylene terephthalate (PET) fiber reinforced polyoxymethylene (POM) hybrid composite

Environmental concerns have attracted researchers to study the recycling of composite materials and thermoplastics due to the desire not to waste materials and reduce disposal of scraps that may eventually pollute the environment. The main objective of this article is to study the effect of recycling on the mechanical properties of kenaf fiber/PET reinforced POM hybrid composite. The virgin hybrid composite was produced by compression molding and later subjected to mechanical testing. The scraps obtained after the mechanical testing were shredded, granulated and subjected to compression molding to produce samples for mechanical testing. Tensile strength of 27 MPa was obtained and (after second recycling process) which is lower compared to 73.8 MPa obtained for the virgin hybrid composite. There was a significant increase in flexural modulus (4.7 GPa) compared to the virgin hybrid composite. The impact strength dropped to 4.3 J cm^?1 as against 10.5 J cm^?1 for the virgin hybrid composite. The results of thermal degradation showed about 80% weight loss for kenaf fiber between 300 and 350°C. The weight loss may be due to the degradation of cellulose and hemicellulose content of the fiber. The percentage water absorption of the recycled composite dropped by about 80% compared to the virgin hybrid composite. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39831.     

Alkali dissolution behaviour of sea–island‐type polyethylene terephthalate ultramicrofibre knitted fabrics

Sea–island‐type polyethylene terephthalate ultramicrofibre (0.007 denier per filament) with a single fibre diameter of ca. 800 nm has been produced over the last 4 years. Three kinds of sea–island‐type polyethylene terephthalate knitted fabric manufactured from this ultramicrofibre were alkali treated, and their dissolution behaviour was investigated. It was found that the dissolution ratio was dependent upon temperature and sodium hydroxide concentration in the alkali treatment. Practical dissolution ratios mostly reached the theoretical values after alkali treatment with 1.0% (w/w) sodium hydroxide solution at 95 °C for 40 min in all samples. Alkali dissolution of the sea component and revealing of the island component were confirmed by differential scanning calorimetry and scanning electron microscopy. Alkali dissolution behaviour could also be monitored indirectly by the cationic dye staining method. While all untreated samples exhibited high colour yield values after cationic dyeing, alkali‐treated samples showed reduced colour yield values with increasing alkali treatment time and a final levelling‐off point.     

Niobium compound catalyst for polycondensation reaction to form polyethylene terephthalate(PET)

A catalytic mechanism of PET formation was investigated and new types of tin and antimony catalysts were designed. On the basis of the investigation a new type of niobic acid has been found as an effective catalyst. The result was confirmed with a pilot plant which is a type of continuous thin layer polycondensation method. Niobic acid prepared by hydrolysis of NbCl₅ with NaOH was very effective, whereas one prepared with NH₄OH showed no activity. Coloration of PET, however, remains as an unresolved problem.     

A study on the biodegradability of polyethylene terephthalate fiber and diethylene glycol terephthalate

The degradation of diethylene glycol terephthalate (DTP) and polyethylene terephthalate fiber (PET fiber) by microbes and lipase was studied. The HPLC method was used to determine the degradation ratio and degradation rule of DTP. Greater than 90% DTP was degraded by microbes in 24 days and 40% by lipase in 24 h. The degradation of DTP can be described by the first‐order reaction model. Although the biodegradation ratio of PET fiber was still weak, we demonstrated with SEM micrographs and HPLC analysis that microbes and lipase could act on the PET fiber and there were some cracks on the surface of the fiber. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 1089–1096, 2004     

The development of microstructure in oriented polyethylene terephthalate (PET) during annealing

This work concerns the changes in structural order, which occur when amorphous polyethylene terephthalate (PET) is crystallised by drawing and then subsequent annealing. Real time wide angle X-ray fibre diffraction is used to obtain information about the microstructural changes taking place during drawing and subsequent annealing. The diffraction patterns obtained proved the existence of a liquid crystalline transient mesophase prior to crystallisation. The development of both the mesophase and the crystalline structure are also studied using small angle X-ray scattering during annealing of uniaxially drawn samples held at constant strain. These experiments proved the absence of any microstructure associated with the mesophase and that significant microstructural changes take place only when crystallisation starts to occur.     

Computer‐aided mathematical modeling and numerical simulation and theoretical analysis of the polypropylene polymer air drawing in spunbonding nonwoven process

In this article, as a nonlinear mathematical problem, the air‐drawing model and the air jet flow field model of the polymer during spunbonding process are also presented, because the continuous filament fiber not always occurs in the spunbonding process, therefore, there exists the filament fiber breakage, the broken fibers occur in the flow field of spunbonding process is a two‐phase flow problem, we suggested a new model called the sphere–spring model that can best described the broken fibers movement features. At the same time, the air‐drawing model of the polypropylene polymer in a spunbonding process is presented and solved by introducing the numerical computation results of the air jet flow field of aerodynamic device. The model's predictions of the filament fiber diameters, crystallinities, and birefringences are coincided well with the experimental data. The effects of the processing parameters on the filament fiber diameter are discussed. A lower polymer throughput rate, lower quench air temperature, higher polymer melt initial temperature, higher air initial temperature, higher air initial speed, medium smaller venturi gap, higher air suction speed, higher quench air pressure, higher air suction speed, higher extrusion temperature, higher quench air pressure, higher cooling air temperature, and so on can all produce finer filament fiber. The results show great prospects for this research in the field of computer‐assisted design of spunbonding technology. POLYM. ENG. SCI., 54:481–492, 2014. © 2013 Society of Plastics Engineers     

Antimicrobial polyethylene terephthalate (PET) treated with an aromatic N‐halamine precursor,m‐aramid

A commercial m‐aramid as N‐halamine precursor has been coated onto polyethylene terephthalate (PET) fabric surface by pad‐dry‐curing process. The process is accomplished by padding the scoured PET fabric through the homogeneous m‐aramid solution, drying at 150°C for 3 min, and curing at 230°C for 3 min. The PET surface coated with m‐aramid was characterized using fourier transform infrared‐attenuated total reflection (FTIR‐ATR) spectroscopy, X‐ray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM). FTIR exhibits new bands in the 1645 and 1524 cm^?1 regions as characteristic of m‐aramid bands, which indicate the PET fabric coated with m‐aramid. XPS results show a distinguishable peak at binding energy 398.7 eV, which confirms the nitrogen atom of m‐aramid on the PET surface. In addition, SEM image shows a layer of coating onto the PET surfaces, which demonstrates the presence of m‐aramid coating on the surface of the PET. After exposure to dilute sodium hypochlorite solution, exhibition of antimicrobial activity on the coated PET is attributed to the conversion of N‐halamine moieties from the N‐halamine precursor. The chlorinated PET showed high antimicrobial activity against Gram‐negative and Gram‐positive bacteria. The chlorinated PET coated with 10% m‐aramid exhibited about 6 log reductions of S. aureus and E. coli O157:H7 at a contact time of 10 and 30 min, respectively. Furthermore, the antimicrobial activity was durable and rechargeable after 25 wash cycles. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Compatibilization of polyethylene terephthalate/polypropylene blends with styrene–ethylene/butylene–styrene (SEBS) block copolymers

Blends of polyethylene terephthalate (PET) and polypropylene (PP) at compositions 20/80 and 80/20 were modified with three different styrene–ethylene/butyl–ene-styrene (SEBS) triblock copolymers with the aim of improving the compatibility and in particular the toughness of the blends. The compatibilizers involved an unfunctionalized SEBS and two functionalized grades containing either maleic anhydride (SEBS-g-MAH) or glycidyl methacrylate (SEBS-g-GMA) grafted to the midblock. The effects of the compatibilizers were evaluated by studies on morphology and mechanical, thermal and rheological properties of the blends. The additon of 5 wt % of a SEBS copolymer was found to stabilize the blend morphology and to improve the impact strength. The effect was, however, far more pronounced with the functionalized copolymers. Particularly high toughness combined with rather high stiffness was achieved with SEBS-g-GMA for the PET-rich composition. Addition of the functionalized SEBS copolymers resulted in a finer dispersion of the minor phase and clearly improved interfacial adhesion. Shifts in the glass transition temperature of the PET phase and increase in the melt viscosity of the compatibilized blends indicated enhanced interactions between the discrete PET and PP phases induced by the functionalized compatibilizer, in particular SEBS-g-GMA. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 65:241–249, 1997     

Durable flame‐retardant treatment of polyethylene terephthalate (PET) and PET/cotton blend using dichlorotribromophenyl phosphate as new flame retardant for polyester

Dichlorotribromophenyl phosphate (DCTBPP) was synthesized via the reaction of tribromophenol and phosphorous oxychloride and characterized by elemental analysis, IR, ¹H‐NMR, thermogravimetric analysis, and differential scanning calorimetry. To impart durable flame retardancy the poly(ethylene terephthalate) (PET) fabric was treated with DCTBPP via pad–dry–thermosol fixation and the PET/cotton (50/50) blend fabric was treated with both DCTBPP and tetrakis(hydroxymethyl) phosphonium chloride (THPC)/urea precondensate via a two‐bath sequential treatment. The treated PET fabric's increased limiting oxygen index value was proportional to the increasing DCTBPP application level and showed self‐extinguishing properties at 8.1% add‐on, even after 50 washes. The blend fabric treated with 15% DCTBPP and 30% THPC/urea precondensate became self‐extinguishable and durable to 50 washes, and the treated fabric retained over 85% of its breaking strength without excessive stiffness. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 793–799, 2001     

A mathematical model for the prediction of damage in concrete

A mathematical model was developed to describe the compressive stress-strain behaviour of concrete, mortar and cement paste. The determination of a suitable stress-strain function was necessary to determine the energy dissipated in damage on loading. Previous research had shown that the envelope of the cyclic loading sequence used in assessing damage was the stress-strain curve obtained by monotonic loading. The amount of plastic strain on unloading was determined by constructing a pseudo-stress conventional strain curve. Comparison with experimental results indicated that the model for the prediction of the stress-strain curve provided good correlation. Similarly, predictions of change in initial elastic modulus and energy dissipated in damage were also in close agreement with the experimentally obtained values.     

Effect of fiber surface morphology on the hydrophilicity modification of cold plasma‐treated polypropylene nonwoven fabrics

Cold oxygen plasma was employed to give hydrophilicity modification to polypropylene (PP) nonwoven fabric (NWF). It was found that, after plasma treatment, PP NWF made from fibers with smooth surfaces can only keep its hydrophilicity for a short time and then shows a quick hydrophobic recovery at room temperature. However, this hydrophilic property can last for a long time in the case of the PP NWF made from fibers with rough surfaces. To prove the contribution of the rough surface to the long‐term hydrophilicity, this PP NWF was treated in an organic solvent to smooth the fiber surface. The hydrophilic feature of this PP NWF no longer lasts for a long time after the same plasma treatment. This observation strongly supports our opinion that the fiber surface morphology of PP NWF is a critical factor for long‐term hydrophilicity improvement after plasma treatment, which gives a positive solution to overcoming the aging effect of hydrophilicity modification often found in this technique. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Preparation and characterization of poly(ethylene terephthalate) fabrics treated by blends of cellulose nanocrystals and polyethylene glycol

In this study, the coating based on the blends of low molecular weight polyethylene glycol (PEG) and cellulose nano‐crystals (CNC) was introduced to immobilize on the surface of polyethylene terephthalate (PET) fabrics to modify the surface properties of fabrics, and to fabricate comfortable fabrics for formidable climate. Field‐emission scanning electron microscope, attenuated total reflectance Fourier transform infrared spectroscopy, and differential scanning calorimetry (DSC) were employed to study the topography, superficial ingredients, and thermal activity of the finished fabrics. The observation of field‐emission scanning electron microscope and attenuated total reflectance Fourier transform infrared spectroscopy confirmed that the surface of PET fabrics was covered by CNC/PEG1000/PEG600 coating. The transition onset temperature and phase change enthalpy of PET fabrics treated with CNC/PEG1000/PEG600 were at 7.06°C and 11.41 kJ/kg, respectively. Dimensional memory measurement demonstrated that the introduction of CNC caused the deformation percent to decrease by about 41% for PET fabrics covered with CNC/PEG1000/PEG600 coating. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Investigation into etching mechanism of polyethylene terephthalate (PET) films treated in helium and oxygenated‐helium atmospheric plasmas

This research makes an investigation into the etching mechanism of atmospheric plasma conditions on the surface of polyethylene terephthalate (PET) films. Two types of untreated PET films (S/200 and S/500) were exposed to plasma for 0 to 5.0 min in 30‐s increments. The first set of each film type was treated in helium plasma, while the second was treated in oxygenated‐helium plasma. Differential Scanning Calorimetry (DSC) was used to characterize pre‐ and post‐exposure films. Weight changes and the degree of solubility were also determined. Based on peak area results, the percent crystallinity of PET S/200 increased by an average of 4.57% (helium treated) and 13.56% (oxygenated‐helium treated), while the S/500 showed only a small increase. There was no significant change in the melting or crystallization temperatures of either film type, indicating a decrease in amorphous content versus an increase in crystalline material. Weight loss analysis supports this theory. Solubility testing revealed a continual decrease in swelling as exposure time was increased. A model was developed to predict the change in the degree of solubility for polyphase surfaces considering the etching rate per phase. The model was applied to PET with good correlation between the model and experimental data. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 2383–2389, 2004