Poly Trimethylene Terephthalate Research Articles

Long-Term Characteristics of Prestressing Force in Post-Tensioned Structures Measured Using Smart Strands

The proper distribution of prestressing force (PF) is the basis for the design of prestressed concrete (PSC) structures. However, the PF distribution obtained by predictive equations of prestress losses has not been sufficiently validated by comparison with measured data due to the poor reliability and durability of conventional sensing technologies. Therefore, the Smart Strand with embedded fiber optic sensors was developed and applied to PSC structures to investigate the long-term characteristics of PF distribution as affected by concrete creep and shrinkage. The data measured in a 20 m-long full-scale specimen and a 60 m-long PSC girder bridge were analyzed by comparing them with the theoretical estimation obtained from several design equations. Although the long-term decreasing trend of the PF distribution was similar in the measurement and theory, the equation of Eurocode 2 for estimating the long-term prestress losses showed better agreement with the measurement than ACI 209R and ACI 423.10R did. This can be attributed to the more refined form of the predictive equation of Eurocode 2 in dealing with the time-dependency of the PF. The study results also confirmed the need to compensate for the temperature variation in the long-term monitoring to derive the actual mechanical strain related to the PF. We expect our developed Smart Strand to be applied practically in PF measurement for the reasonable safety assessment and maintenance of PSC structures by improving several of the existing drawbacks of conventional sensors.

An Insight into Phenomenology of Polytrimethylene Terephthalate Fibrillation

An Insight into Phenomenology of Polytrimethylene Terephthalate Fibrillation

An Insight into Phenomenology of Polytrimethylene Terephthalate Fibrillation

AbstractThe objective of this work is to analyze the effect of the processing temperature on fibrillation of the dispersed phase and to correlate melt viscoelastic responses to formed morphologies. A blend system of polypropylene (PP)/polytrimethylene terephthalate (PTT) with varying ratios (PP/PTT: 99/1, 94/6, 90/10, and 80/20) is prepared on a co‐rotating twin screw extruder, and then pelletized blend samples are fed into a laboratory mixing extruder to spin monofilaments at three different orifice temperatures of 180, 195, and 240 °C. As revealed by scanning electron microscopy, a nano‐fibrillar morphology forms after employing spinning. Rheological approach performed in the linear region shows a transition from terminal trend into non‐terminal trend in the low‐frequency region when the fibrillar morphology forms, the magnitude and width of which are reflective of the fibril growth. Transient stress measurements prove its capability to enable the blend system to show potentials of morphology development during dynamic tests. Startup of steady shear flow shows that after reaching the percolation concentration of dispersed phase, fibril–fibril coalescence leads to the formation of long fibrils whose contribution to the blend system increases the elasticity of the blend fibers.

Exploring Dual-Substrate Cultivation Strategy of 1,3-Propanediol Production Using Klebsiella pneumoniae.

1,3-Propanediol (1,3-PDO) has numerous industrial applications in the synthesis of the monomer of the widely used fiber polytrimethylene terephthalate. In this work, the production of 1,3-PDO by Klebsiella pneumoniae is increased by dual-substrate cultivation and fed-batch fermentation. Experimental results indicate that the production of 1,3-PDO can be elevated to 16.09g/L using a dual substrate ratio (of glucose to crude glycerol) of 1/30 and to 20.73g/L using an optimized dual-substrate ratio of 1/20. Ultimately, the optimal dual-substrate feeding for a 5L scale fed-batch fermenter that maximizes 1,3-PDO production (29.69g/L) is determined. This production yield is better than that reported in most related studies. Eventually, the molecular weight and chemical structure of 1,3-PDO were obtained by FAB-MS, 1H-NMR, and 13C-NMR. Also, in demonstrating the effectiveness of the fermentation strategy in increasing the production and production yield of 1,3-PDO, experimental results indicate that the fermentation of 1,3-PDO is highly promising for commercialization.

Forensic Fiber Analysis by Thermal Desorption/Pyrolysis-Direct Analysis in Real Time-Mass Spectrometry.

The thermal desorption/pyrolysis-direct analysis in real time-mass spectrometry (TD/Py-DART-MS) method was developed for the analysis of fibers in this study. The fiber samples were pyrolyzed with a temperature gradient and the pyrolysis products were determined by DART-MS. The pyrogram from the TD/Py-DART-MS fiber analysis was found to be associated with the physical properties such as the melting points. At the same time, the TD/Py-DART-MS allows the analyst to obtain the chemical information such as polymeric backbone structures and dyes on the fiber. The pyrolysis profiles of common polymeric fibers in textile materials such as cotton, cellulose triacetate (CT), poly(caprolactam) (nylon-6), poly(hexamethylene adipamide) (nylon-6/6), poly(acrylonitrile) (PAN), poly(ethylene terephthalate) (PET), poly(butylene terephthalate) (PBT), poly(propylene) (PP), and polytrimethylene terephthalate (PTT) and their respective characteristic mass spectra were reported in this study. The fibers from 40 commercial textile samples were analyzed by the TD/Py-DART-MS method, and the statistical methods including principal component analysis (PCA) and Pearson product moment correlation (PPMC) were applied to classify and associate the fibers based on their mass spectral data. The strong correlation between the reference fiber mass spectral profiles and tested fiber mass spectral profiles was observed by using the PPMC method, and the identification accuracy was 97.5%. When combined, the mass spectral and pyrogram data, the types of fibers including the blended fibers were identified effectively. The TD/Py-DART-MS method also demonstrated the promising capability for the identification of dyes on fibers. Overall, the TD/Py-DART-MS method requires small sample size and minimal sample preparation but offers reproducible and multidimensional information for the fiber evidence rapidly (i.e., ∼6.7 min). Since the proposed method is simple to perform and the data are easy to interpret, this approach may significantly contribute to the fiber identification and comparison procedures in forensic settings with high sample throughput potential.

Large strain-tolerated smart steel strand with built in coaxial cable Fabry–Perot interferometer

A steel strand is the principal force-bearing structural member, and its stress state must be monitored throughout its entire service process. A previously developed optical fiber sensor-based smart steel strand has accomplished self-sensing but with a limited measuring range, and cannot monitor the strain entirely until the steel strand fails. This study aims to develop a large strain-tolerated coaxial cable Fabry–Perot interferometer (CCFPI) smart steel strand. Firstly, a thin CCFPI sensor was proposed by the clamping method using an SF047-type coaxial cable. The test results show that its measuring range can reach up to 140,000 με. Subsequently, a glass fiber reinforced polymer (GFRP)-CCFPI smart bar was developed by packaging the CCFPI sensor in a GFRP. Encouraging results of the tensile test were achieved, indicating that the smart bar provides reliable and accurate strain measurements with a dynamic range of 16,000 με. Finally, the CCFPI smart steel strand was further developed by replacing the core wire of the steel strand with the GFRP–CCFPI bar. The experimental results show that the tensile strength and elastic modulus of the smart strand were 86.7% and 89.4% of that of the common steel strand, respectively. Moreover, the smart strand was proved to have a large self-sensing range and its tension or stress can be calculated accurately using the strain measured by itself.

Physical Properties and Wear Comfort of Bio-Fiber-Embedded Yarns and their Knitted Fabrics According to Yarn Structures

Abstract This study examined the physical properties of polytrimethylene terephthalate (PTT)/Tencel/cotton air vortex yarns and the wear comfort of their knitted fabrics for high emotional garments. In fine yarn count, the initial modulus of the air vortex yarn was similar to the ring yarn because of the elastic property of the PTT fibers in the yarns. In particular, the thermal shrinkage of the air vortex yarns was higher than that of the ring yarns because of the sensible thermal shrinkage of the PTT fibers, which resulted in higher relaxation shrinkage of the air vortex knitted fabric than those of ring and compact knitted fabrics. On the basis of the wear comfort, the air vortex yarns are compatible with winter textile goods. The pilling of the air vortex knitted fabric was superior to that of the ring and compact yarns. The tactile hand of the air vortex yarn knitted fabrics was stiffer than that of the ring and compact yarn knitted fabrics. However, the harsh tactile hand of the air vortex knitted fabric was estimated to improve in the thinner fabrics by the low elastic modulus of fine yarn because of the PTT fibers in the air vortex yarns.

Fabrication of Polypropylene (PP)/Poly Trimethylene Terephthalate (PTT)/Nanoclay Nanocomposite Fibers with Tailored Properties

The main aim of this study was to deal with one of the major drawbacks of polypropylene (PP) fibers, i.e., low resiliency and low dyeability, by incorporating polytrimethylene terephthalate (PTT) fibrils, as a dispersed material, and organoclay, as a nano-filler, into the PP polymer matrix. The presence of 10 wt% of PTT and 0.5–1 wt% organoclay in the PP nanocomposite fibers led to an approximately 18.5% and 45.5% increase in the resilience behavior and dye uptake, respectively, compared to pure PP fibers, without using highly toxic carriers. The lowest mean diameter of the nano-fibrils was 75 nm for the hot drawn nanocomposite fiber samples as measured by scanning electron microscopy (SEM). The results of DSC indicated that the presence of both PTT and organoclay significantly influenced the crystallinity of the PP which also confirmed their nucleating effects in the nanocomposite fiber.

Transfer Lengths in Pretensioned Concrete Measured Using Various Sensing Technologies

Although pretensioned concrete structures have increasingly been used worldwide, a number of design issues need to be addressed to further improve the structural performance. Transfer length of pretensioned members was investigated with several test variables in this study by adopting various sensing technologies including the Smart Strands with embedded fiber optic sensors. The effect of increased strength in 2360 MPa high-strength strand on the transfer length was also analyzed. Representative provisions widely used in design were compared with the test results for consistency and appropriate conservatism. The strain distribution required for the transfer length depended partly on the type and location of sensors, which suggests the challenges associated with reasonable determination of the transfer length. According to the results of the analysis, the predictive equation in ACI 318 was relatively accurate and conservative under various conditions including high-strength strands. However, the transfer lengths based on the strand strains rather than the conventional surface strains of concrete require further investigation depending on the bonding behavior between the strand and the surrounding concrete inside a member. Thus, this study also introduces a new sensing technology utilizing the Smart Strand to reliably measure the strain distribution along a strand.

DuPont details unwanted businesses

DuPont, which will separate from DowDuPont on June 1, has disclosed the 10% of its business portfolio that it no longer wants and is likely to sell. DowDuPont officials previously said they wanted to divest 10% of the DuPont portfolio but were scant on details. DuPont will transfer the businesses, which have combined annual sales of about $2 billion, to a new “noncore” operating segment. Included in this group is DuPont’s stake in Hemlock Semiconductor, a silicon joint venture with Corning and Shin-Etsu Handotai. Also in the mix is its biomaterials business, which has a 1,3-propanediol fermentation joint venture with the sugar maker Tate & Lyle. The biomaterials business also makes polytrimethylene terephthalate, a propanediol derivative used in fibers and engineering polymers. Another noncore business is Photovoltaic Solutions and Advanced Materials, which makes metallization pastes and silicone encapsulants. DuPont Clean Technologies, a supplier of technologies for sulfuric acid production and

Towards a plastic engine: Low—temperature tribology of polymers in reciprocating sliding

Fundamental tribological studies of a range of engineering polymers, including a bio-derived Polytrimethylene-terephthalate (PTT) have been conducted at low temperatures (12C∘ and −8C∘). The aim of the study was to replace a conventional honed aluminium liner/polytetrafluoroethylene (PTFE) seal interface with a polymer combination, within a Dearman Engine. The Dearman Engine is a novel piston engine driven by the expansion of a cryogenic fluid, either liquid nitrogen or liquid air, to produce emissions-free combined cooling and power. A tribometer was used to simulate engine conditions.The efficacy of the polymers relative to the honed aluminium benchmark was assessed in terms of a projected material transfer layer. The magnitude of which was determined using a combination of scanning electron microscope (SEM)/energy-dispersive X-ray spectroscopy (EDS) and Abbott—Firestone curves, a descriptor of surface texture. The concept of a frictional overshoot, correlated with the severity of wear measured on the PTFE specimen, is introduced.For the engine, a low coefficient of friction (CoF) leads to reduced parasitic losses and low wear will ensure the integrity of the piston seal is maintained, and so to the sealing capacity of the engine. Material transfer, generally from seal to liner specimens was detected in all but the unhoned polyoxymethylene (POM) and unhoned Aluminium samples. These two combinations had the lowest frictional overshoots and the lowest levels of wear. These are properties that were also linked to a low surface roughness and a low gradient of the interquartile range of the Abbott-Firestone curve. These materials both outperformed the benchmark seal/liner combination and the POM provides the potential for an all polymer expansion chamber.

Application of natural dye on polytrimethylene terephthalate fiber

PurposeThis paper aims to investigate the feasibility of developing an eco-friendly dyeing process for a regenerated polyester fiber (polytrimethylene terephthalate) using a natural dye (Lac) and bio-mordant.Design/methodology/approachThe effects of temperature, time, initial pH of dye bath, material to liquor ratio and mordant concentration on color strength of polytrimethylene terephthalate fiber dyed with Lac were examined. The results were compared using three bio-mordant (catechu, myrobalan and pomegranate) and three inorganic mordant (alum, ferrous sulfate and stannous chloride). Single replicate of 25-design methodology was used to identify three significant factors affecting color strength, and optimization was done using response surface methodology based on 23-central composite rotatable design.FindingsColor strength achieved using catechu as a bio-mordant was close to that with ferrous sulfate and higher than with stannous chloride. Temperature, initial pH and mordant concentration were identified as significant factors affecting color strength of dyed fiber with catechu. Optimization revealed temperature of 133OC, initial pH of 6 and bio-mordant (Catechu) concentration of 10 per cent to be the optimal conditions for dyeing, with K/S value of 4.55.Originality/valueThe study revealed the possibility of satisfactory dyeing of regenerated polyester fibers with natural dyes, replacing disperse dyes. The comparison of color strength achieved indicated the possibility of replacing inorganic mordant with bio-mordant in such dyeing process. The dyeing process could thus be made more eco-friendly by removal of toxic chemicals from effluents.

Effect of Dimethyl 1,4-Cyclohexane Dicarboxylate on Mechanical Properties and Crystallization Behavior of Polytrimethylene Terephthalate Co-Polymer

Dimethyl 1,4-cyclohexane dicarboxylate (DMCD) is formed as an impurity when dimethyl terephthalate (DMT) is manufactured from biomass. Because the boiling point of DMCD is similar to that of DMT, DMCD is known to add considerable cost to the separation and refinement. This prompted us to investigate the effect of the presence of varying amounts of DMCD on the physical properties of poly(trimethylene terephthalate) (PTT), which is manufactured from DMT. In the present study, a small amount of DMCD (1-5 mol% of DMT) was added when manufacturing PTT through the polycondensation of DMT and propanediol (PDO). The results of the analysis of the thermal properties indicated that the glass transition temperature and melting temperature showed a decreasing tendency as the DMCD content increased. The thermal stability increased by 25 °C compared to that of virgin PTT. The iso-thermal scanning analysis showed that the crystallization rate with 1 mol% of DMCD increased compared to that of virgin PTT, whereas the crystallization rate decreased with a higher DMCD content. The mechanical properties are noteworthy. The tensile strength and the tensile strain were simultaneously improved with the addition of DMCD, and the initial modulus remained nearly constant within the range of this experiment. Particularly, the tensile strength increased by a maximum of 15% (76.5 MPa) compared to that of virgin PTT. The physical properties of the PTT co-polyester significantly changed when the DMCD content was 2 mol%. Overall, the thermal properties remained similar, the crystallization rate increased, and the thermal stability and mechanical properties were significantly improved up to 2 mol%. Furthermore, the viscosity and crystal structure were examined by capillary rheometry and X-ray diffraction (XRD) to investigate the changes in these two properties. We concluded that the presence of bio-byproducts such as DMCD enhances the mechanical properties of PTT, such as the tensile strength and strain.

Friction characteristics of post-tensioning tendons in full-scale structures

Friction characteristics between the strands and the duct have a significant effect on the distribution of prestressing force and can be incorporated by the curvature and wobble friction coefficients in the design of prestressed concrete structures. However, the recommended friction coefficients show a wide range of variation, which can cause the inaccurate estimation of prestressing force. In this study, the friction coefficients were evaluated based on the strains of tendons measured by Smart Strands using optical fiber sensors in a full-scale test specimen and two actual long-span girder bridges. The test specimen was investigated to determine how the duct shapes and other factors affect the friction coefficients. Simultaneous equations method and least squares method for obtaining friction coefficients were employed and the results were compared in the actual bridges. This study shows one of the applications of the developed Smart Strand system that can overcome several drawbacks of the existing measurement system.

Thermal and UV Resistance of Polytrimethylene Terephthalate Bulked Continuous Filament (PTT BCF) and The Influence of Additive on Those

Thermal and UV Resistance of Polytrimethylene Terephthalate Bulked Continuous Filament (PTT BCF) and The Influence of Additive on Those

Advances in bioconversion of glycerol to 1,3-propanediol: Prospects and challenges

Abstract 1,3-Propanediol, a monomer for synthesis of polytrimethylene terephthalate, polyethers, polyurethanes, and heterocyclic compounds, has attracted worldwide attention. It can be produced from renewable resources using microorganisms, which focus mainly on the ecologically friendly process, industrial safety and sustainable development. This review summarized and commented in the view of bioprocess and bioengineering, especially on bioconversion of glycerol into 1,3-PD since 2010. Various strategies for microbial production of 1,3-PD from glycerol including strains screening and improvement, two-step and multi-stage fermentation, sole and co-substrate fermentation, co-culture, and microbial consortium were reviewed and compared. Besides experiments, theoretical analyses, such as fermentation kinetics, stability and robustness analysis, metabolic and system engineering analysis were also highlighted. The present strategies of the downstream processing of 1,3-PD were compared according to their advantages and drawbacks. Meanwhile, the novel technology of microbial electrosynthesis for biochemicals was well introduced and discussed. Finally, The future prospects and challenges of 1,3-propanediol from biotechnology were discussed for its industrial production.

Estimation of Tendon Force Distribution in Prestressed Concrete Girders Using Smart Strand

The recently developed smart strand offers the possibility of measuring the prestress force of the tendon from jacking and all along its service life. In the present study, a method estimating the force distribution in all the tendons of a prestressed concrete (PSC) girder installed with one smart strand is proposed. The force distribution in the prestressed tendons is formulated by the friction and the anchorage slip, and is obtained through an optimization process with respect to the compatibility conditions and equilibrium of the forces in the section of the PSC girder. The validation of the proposed method through a numerical example and experiment shows that it can be used to estimate the force developed in the tendon.

Mechanical recyclability of technical biopolymers: Potential and limits

The mechanical recyclability of the technical biopolymers polytrimethylene terephthalate (PTT), cellulose acetate butyrate (CAB), polybutylene succinate (PBS) and polyhydroxy alkanoate blend (PHBV/PBAT) was evaluated by assessing the effect of repeated polymer processing (extrusion without further compounding with virgin material or additives) on the material structure and mechanical properties. Reprocessing-induced hydrolytic degradation was found to be the prevalent aging mechanism of the investigated biopolymer grades. However, susceptibility to hydrolysis, and thus maintenance of the performance characteristics, differed strongly between the biopolymer types. To that effect, PTT and CAB especially exhibit a high potential for mechanical recycling. By taking advantage of appropriate additivation, the mechanical recyclability of PBS and PHBV/PBAT is also assumed to be high.

Analytical Model of Nonlinear Stress-Strain Relation for a Strand Made of Two Materials.

Unlike conventional steel strands, the smart strand supports strain-measuring function and adopts different materials for its core wire and helical wires. This study intends to analytically derive the nonlinear stress-strain model of this strand made of two materials. The effect of the bending moment and torsional moment of the helical wires on the overall load within the range of geometric shapes shown by actually used strands is verified to be negligible and is thus ignored in order to simplify the analytical model. Moreover, the slight difference between the actual and analytic behaviors, which only appears in the slope varying part in the case of bilinear behavior, such as that of steel, is also ignored. The proposed constitutive model of the smart strand obtained by introducing the experimental stress-strain relation between the carbon fiber reinforced polymer core wire and the helical steel wires is in good agreement with the experimental data. The previous analytical models are applicable only to strands made of a unique linear material, whereas the model proposed in this study is also applicable to strands in which the core wire and the helical wires are made of two different materials, exhibiting nonlinear behavior.

The research and development of seamless knitted shapewears made of PTT filament

PurposeThe purpose of this paper is to improve the comfort and shaping function of seamless shapewear on the material and structure and develop new seamless shapewear products. The shaping figure effect will be verified as well.Design/methodology/approachThe performance of the knitted fabrics made of Polytrimethylene terephthalate (PTT) filament was analyzed by orthogonal experiment and fuzzy mathematical methods analysis, in order to get the optimal conditions for the best performance. The new products were designed and made based on the results of the material research with the consideration of the aesthetic requirements. The shaping effect of seamless shapewears on local and global figure was tested by the methods of the combination of subjective and objective evaluation.FindingsThe sample which renders the optimal performance for shapewear is the one with PTT filament as face yarn, nylon core-spun yarn as ground yarn and 3+1 simulate rib knit structure. The material of face yarn, mixed proportion and structure can influence the shape retention, appearance and comfort of PTT fabric in various degrees. Three shapewears which were developed according to the results of material research have different shaping effect. And women with different figures put different satisfaction degrees on each shapewear’s shaping effect.Practical implicationsThis paper provides scientific basis and reference for enterprise to design good tight seamless shapewear as well as for consumer to buy suitable products.Originality/valueIn the view of the problems of present shapewears, this paper completed the development of the shapewears and verified the shaping effect of them on women with different figures. The shapewears can be put into production directly.