Heat-setting Temperature Research Articles

Effect of thermal stress on the life of DC link capacitors for smart grid

Thermal stress is an important factor affecting the life of a DC link capacitor (DCLC). However, relevant studies on thermal stress mechanism directly influencing the lifetime of the capacitor are rarely reported. In this paper, the heat setting and thermal stress of DCLC has been analyzed, and the relevant experimental platforms have been developed to evaluate the breakdown strength of DCLC at two heat setting temperatures (HSTs). Simultaneously, the life aging analysis of DCLC at different HSTs and the life aging tests at various temperatures were also executed to attain insights into the influence of thermal stress on the lifetime of DCLC. The results showed that the stress caused by heat setting and operating temperature influenced the breakdown voltage capability and the lifetime of DCLC. With an increase in HST by 5 °C, a step-increase in the withstand voltage capability of DCLC from 7,000 V to 7,200 V was observed that demonstrated an enhancement of 2.86% in the breakdown strength performance. Correspondingly, the lifetime of DCLC with a capacitance change rate of -3% enhanced from 1,500 h to 1,700 h. However, severe deterioration in the life span of DCLC from 4,200 h to 500 h was observed with an increasing operating temperature from 55 °C to 85 °C, respectively. The lifetime could be enhanced by increasing the HST as well as reducing the operating temperature. The presented results could be termed a harbinger for industrial production of high-performance DCLC with enhanced lifetime that augers well for high-power applications.

Analyzing the dyeing behaviour of easy dyeable and regular polyester by the influence of different heat-setting temperature

The heat-setting effects of easy-dyeable polyester (EDP) have been investigated by comparing it with regular polyester fabric (PES). Using XRD analysis, the crystallinity and amorphousness of the easy-dyeable polyester and regular polyester fabric were assessed after 45 s during heat-setting of EDP and PES at nominal temperatures (120, 140, 160, 180, and 200 °C). The heat-set of EDP and PES fabric were dyed separately and competitively at temperatures ranging from 100 to 130 °C using S-type (C.I. Disperse Red 167) and E-type (C.I. Disperse Red 60) dyes. The color strength (fk ) and dye uptake were found to be lower at the heat-setting temperatures of 180 °C for PES and 140 °C for EDP. To ascertain the impact of varying heat-setting temperatures on PES and EDP-dyed fabric, the dimensional stability and GSM were assessed. When the heat set temperature was raised from 140 °C, the EDP fabric showed greater dimensional stability. On the other hand, the dimensional stability of untreated PES fabric (−4.2% lengthwise) and GSM (111 g/m2) gradually stabilized when the heat-setting temperature increased. However, the color fastness rating has improved after applying the heat-setting process for PES and EDP at 180o C and 140 °C, respectively.

Effect of Heat-Setting Temperature on the Structure and Properties of BOPET Film

Effect of Heat-Setting Temperature on the Structure and Properties of BOPET Film

Effect of drawing and heat‐setting process on aggregate structure of Poly(ethylene terephthalate) industrial fiber in large‐scale spinning production

AbstractIt is a vital route to develop new fiber products with various physical‐mechanical properties by which their aggregation structure can be changed via controlling the spinning process parameters. In this study, five groups fiber samples had been obtained by changing the spinneret drawing ratio, two stages drawing ratio and two stages heat‐setting rate. The aggregation structure of the poly(ethylene terephthalate) (PET) industrial fibers from different spinning process was analyzed by combination use of thermal analysis, two‐dimensional wide‐angle X‐ray diffraction (WAXD), small‐angle X‐ray scattering (SAXS), and Infrared Spectroscopy (IR) measurements. It was found that, increasing the spinneret drawing ratio and two stages drawing ratio promoted the orientation and crystallinity within a certain range. For the subsequent two stages heat‐setting process, the disorientation of the amorphous chain is simulated by reducing the relaxation rate and heat setting temperature. Finally, a concise three‐dimensional structure model was established to explain the relationship between aggregation structure and property. These results have important reference for the structure and property analysis of polyester industrial fiber.

Effects of Mechanical Stress on the Life and Insulation Performance of DC-Link Capacitors

Mechanical stress is a crucial factor affecting the life and insulation performance of DC-link capacitors (DCLCs). However, at present, there is a lack of long-term experimental observations on the effects of mechanical stress on the life and insulation performance of DCLCs. The element-winding process for DCLCs is carried out by winding metalized film on a reel and adjusting the various winding tensions and pressures according to performance requirements, usually with a winding tension coefficient (WTC) of kT = 1.5. The pull pressure of the winding machine on the film produces tension during the elements’ winding process, and the tension in the film grows after the heat-setting process. In this study, by adjusting the four tension coefficients of the elements in the winding process, which were 1.4, 1.5, 1.6, and 1.7, various winding tensions of the DCLC components were changed. Additionally, various heat-setting shrinkage tensions were appropriately generated by setting different heat-setting temperatures (HSTs). Relevant test platforms were established, and a life aging test, insulation resistance measurement, and withstand voltage test were performed on these DCLCs at different tension coefficients and HSTs. The obtained results reveal that the mechanical stress of DCLCs is affected by the parameters of the material itself, including the tension coefficient during the winding process and the HST. The winding tension affects the life of DCLCs, such that those with the highest tension (kT = 1.7) demonstrate the longest life at an HST of 105 °C, whereas samples with the lowest tension (kT = 1.4) exhibit the longest life at an HST of 110 °C. HSTs are capable of improving the lifetime of DCLCs. HSTs are also able to improve the withstand voltage capability of DCLCs, but the tension is not proportional to the withstand voltage capability of DCLCs. This research provides a suitable basis for further explorations of the life and insulation performance of DCLCs.

Design, preparation, and performance research of a knitted sensor for respiratory rate detection

Owing to flexible, good wearing comfort and fitting the human body well, flexible knitted sensors can play a significant role in monitoring respiratory signals, an important auxiliary diagnostic information. We proposed an idea that underwear is equipped with flexible sensors to realize respiratory signal detection by daily underwear. Four conductive fibers were used to knit jersey stitches and ribs to produce eight knitted flexible sensor samples. We explored flexible knitted sensors' design and preparation first. Considering the influence of production and daily cleaning on durability, we tested conductive properties, an essential property for sensors before and after heat setting and multi-wash tests. Meanwhile, practical application was tested. The results prove that the most suitable raw materials and knitting structure are 111dtex silver-plated yarn and jersey stitch. Because the sensor fabricated by 111dtex silver-plated yarn has better durability. Washing can optimize its conductivity and the conductivity of sensors fabricated by other conductive yarn is worse than that after washing. Then, the amounts of courses can influence conductivity greatly. Under the same condition, more courses mean better conductivity and durability after washing. Meanwhile, the heat setting temperature can be selected as 100–120 ℃. Because this temperature can promote the conductive properties of most sensors. At last, practical applications prove the feasibility of sensors. There is only a slight gap between the tested by sensors and the actual value. This paper can guide the design of flexible knitting sensors for raw materials and structure. What’s more, it is meaningful for the thermal setting process in the actual production process of the factory. Last but not least, the underwear equipped with sensors based on integrated weaving can detect respiratory frequency accurately. This will make a significant difference in medicine.

Preparation of stereocomplex polylactic acid fiber and evolution of crystal structures

Stereocomplex polylactic acid (ScPLA) fibers were successfully prepared by mixing equal mass melts of poly(L-lactic acid) (PLLA) and poly(D-lactic acid) (PDLA) by melt spinning process. The evolution of crystal structures of ScPLA fibers was investigated by differential scanning calorimetry (DSC) and wide-angle X-ray diffraction (WAXD). The results show that the homogeneous crystal (Hc) will be converted to stereocomplex crystal (Sc) as the heat setting temperature (HT) increases. The crystallinity curves of Hc and Sc cross into an “X” and the cross point is near the melting point of the Hc. The temperature range to form ScPLA fiber with fully stereoscomplex structures is 187 ℃ to 197 ℃ and the maximum Sc content is about 60%.

The synergistic effect of heterogeneous nucleation and stress-induced crystallization on supramolecular structure and performances of poly(lactic acid) melt-spun fibers

As a kind of bio-based polymer, poly (lactic acid) has potential application in fibers fields. Due to the weak nucleation ability, PLA crystallizes slowly and forms large spherulites during the forming process, which deteriorates the properties of PLA fibers. In this work, melt-spun method is employed for the fabrication of PLA/T composite fibers using succinate diphenyl dihydrazide (TMC-306) as the nucleating agent, and then the hot-drawing and heat setting is performed to the as-spun fibers. Compared with pure PLA fibers, PLA/T fibers show faster crystallization rate and improved performance due to the synergistic effect of heterogeneous nucleation and stress-induced crystallization. The characterization of non-isothermal crystallization behavior indicates that the peak crystallization temperature as well as crystallinity of PLA composites is increased to 121.5 °C and 36.78 % respectively by blending 0.3 wt% TMC-306. Meanwhile, the obtained PLA/0.3T composite fibers are highly crystallized and oriented at hot-drawing ratio of 2.4 folds and heat setting temperature of 100 °C, and the conformational stability is noticeably enhanced. Further, the tensile strength and storage modulus of PLA/0.3T composite fiber are 3.46 cN/dtex and 46,953 MPa respectively, which are increased by 42 % and 41 % compared with neat PLA fibers.

Scalable Preparation of Complete Stereo-Complexation Polylactic Acid Fiber and Its Hydrolysis Resistance.

Due to their high sensitivity to temperature and humidity, the applications of polylactic acid (PLA) products are limited. The stereo-complexation (SC) formed by poly(L-lactic acid) (PLLA) and its enantiomer poly(D-lactic acid) (PDLA) can effectively improve the heat resistance and hydrolysis resistance of PLA products. In this work, the blended melt-spinning process of PLLA/PDLA was carried out using a polyester fiber production line to obtain PLA fiber with a complete SC structure. The effects of high-temperature tension heat-setting on the crystalline structure, thermal properties, mechanical properties, and hydrolysis resistance were discussed. The results indicated that when the tension heat-setting temperature reached 190 °C, the fiber achieved an almost complete SC structure, and its melting point was 222.5 °C. An accelerated hydrolysis experiment in a 95 °C water bath proved that the SC crystallites had better hydrolysis resistance than homocrystallization (HC). The monofilament strength retention rate of SC-190 fiber reached as high as 78.5% after hydrolysis for 24 h, which was significantly improved compared with PLLA/PDLA drawn fiber.

Structural Evolution of Polyglycolide and Poly(glycolide-co-lactide) Fibers during In Vitro Degradation with Different Heat-Setting Temperatures.

The structural evolution of polyglycolide (PGA) and poly(glycolide-co-lactide) (P(GA-co-LA)) with 8% LA content fibers with different heat-setting temperatures was investigated during in vitro degradation using WAXD, SAXS, and mechanical property tests. It was found that the PGA fiber was more susceptible to the degradation process than the P(GA-co-LA) fiber and a higher heat-setting temperature reduced the degradation rate of the two samples. The weight and mechanical properties of the samples showed a gradual decrease during degradation. We proposed that the degradation of PGA and P(GA-co-LA) fibers proceeded in four stages. A continuous increase in crystallinity during the early stage of degradation and a gradual decline during the later period indicated that preferential hydrolytic degradation occurred in the amorphous regions, followed by a further degradation in the crystalline regions. The cleavage-induced crystallization occurred during the later stage of degradation, contributing to an appreciable decrease in the long period and lamellar thickness of both PGA and P(GA-co-LA) samples. The introduction of LA units into the PGA skeleton reduced the difference in the degradation rate between the crystalline and amorphous regions, and they were simultaneously degraded in the early stage of degradation, leading to a degradation mechanism different from that of the PGA fiber.

Prediction of Polypropylene Yarn Shrinkage in the Heat-Setting Process Using the Fuzzy Inference System

In the carpet industry, yarn shrinkage is a very important specification, the percent of shrinkage affected by heat setting parameters, time and temperature. In order to obtain the best uniform appearance of carpets, the shrinkage of pile yarns should be minimum in the carpet sizing process. An inappropriate heat set yarn may cause an undesirable shrinkage result and uneven pile height on carpets after the sizing process. It could be useful for manufacturers to understand the optimum condition of heat setting to obtain the low shrinkage of heat set yarns before weaving. Therefore, a fuzzy logic model is designed to predict the shrinkage percentage of polypropylene yarn in different heat setting conditions. Time and temperature are taken into account as input variables and yarn shrinkage is predicted as output. For validation of the model, the yarn samples heat set under various sets of time and temperature and finally yarn shrinkages have been measured experimentally. The result of the fuzzy model prediction compared to regression results and signify the fuzzy results present good and better match with experimental results with the acceptable R2=0.97 and average error (2.59%).

Thermal behaviour of heat treated polyester knitted fabrics

PurposeThermoplastic polymer fabrics are normally heat set to make them dimensionally stable. These fabrics in garment panel form may again be exposed to heat during the processes such as bonding, sublimation printing and cause to change their dimensions. The purpose of this paper is to investigate the response of polyester yarns in knitted fabrics to heat setting and post-heat treatments.Design/methodology/approachIn this study, the thermal shrinkage behaviour of heat set polyester knitted fabrics when subjected to post-heat treatment processes are analyzed using differential scanning calorimetry (DSC) and analysis of fabric shrinkage. DSC is a thermo-analytical technique that measures the difference in the amount of heat needed to increase the temperature of the sample and the reference. A heat flux versus temperature curve is one of the results of a DSC experiment. The polymer structure and morphology of polyester heat-treated and post-heat–treated fabrics were determined by examining the DSC thermograms.FindingsHeat setting and post-heat setting causes the effective temperature of polyester to change. Effective temperature occurred around 160°C for fabrics heat set at low temperatures and increases as the heat setting temperature increases. Post-heat treatments cause to elevate the effective temperature. Shrinkage of fabrics below the effective temperature is not statistically significant while the shrinkage at higher temperatures is significant. Effective temperature is the main determinant of thermal shrinkage behaviour of polyester.Originality/valueThe study reveals the significance of the effective temperature of polyester on heat treatments and post-heat treatments. The study revealed that heat-setting temperature is a primary determinant of the thermal stability of polyester fabric that are subjected to heat treatments.

Effect of Relaxation Heat Setting at Various Temperatures on Molecular Orientation in Polypropylene Fiber

Commercially available polypropylene fiber (PPF) samples with relaxation heat setting for 30 minutes in a drying oven at various temperatures (room temperature, 90 °C, 100 °C, 110 °C, 120 °C, 130 °C, 140 °C, 150 °C, respectively.) were prepared for measurement of their sonic velocity, orientation degree, orientation angle and modulus. According to the obtained data for the PPF molecular orientation before and after the relaxation heat setting, it is found that, with the increasing of relaxation heat setting temperature, the sonic velocity in PPF, orientation degree and modulus decreased, while the orientation angle increased. The result may be helpful to choose proper working temperature for PP hernia patch fabrication.

Effects of Heat Setting on the Morphology and Performance of Polypropylene Separator for Lithium Ion Batteries

In this study, effects of heat setting treatment (pre-set heat setting ratio λ and heat setting temperature Tsetting) on the crystalline structures, orientation status, microporous structures, gas permeability, and electrochemical performance of the separators were studied in detail by means of differential scanning calorimetry (DSC), infrared dichroism, scanning electron microscope (SEM), ultrasmall angle X-ray scattering (U-SAXS), Gurley value test, and electrochemical measurement. It was found that with the decrease of λ or the increase of Tsetting, the melting temperature and degree of crystallinity change regularly and the orientation degree decreases gradually, resulting in small-sized micropores and lower porosity and S/V ratio of the separator. Finally, the gas permeability and ionic conductivity of the separator decreased while the dimensional stability increased. By tuning λ and Tsetting, the microstructure, morphology, and performance of the separators can be efficiently controlled.

Effect of coating process on morphology, bending rigidity and wearability of polyester harness cords

In this article, the harness cords were manufactured by braiding, coating and heat setting at the temperatures of 130 and 195℃, respectively. The film formers used in coating process were poly(butyl acrylate), copolymer size and partial alcoholysis polyvinyl alcohol. The pure film formers' spectra were obtained using in-situ infrared test method on a spectrometer. The scanning electron microscope, bending tester and wearing test device were used to measure the morphology, bending rigidity and wearability of harness cords, respectively. The results showed that the temperature of heat setting changed the molecular structure of coatings, and different influences of temperature on the bending rigidity and wearability of coated harness cords were observed. When the heat setting temperature rose from 130 to 195℃, the bending rigidity of poly(butyl acrylate)-coated harness cord almost kept constant. However, the bending rigidity of copolymer size and polyvinyl alcohol-coated harness cords increased by 33.1% and decreased by 47.4%, respectively. The poly(butyl acrylate) coating presented the best adhesivity to hydrophobic polyester harness cord, and the coated harness cord showed the best uniformity and flexibility as well as higher wearability. After heat setting at 195℃, the wearability of harness cords coated with poly(butyl acrylate), copolymer size and polyvinyl alcohol was increased by 380, 120 and 585%, respectively, when compared with the uncoated one.

Parametric analysis on the temperature response rules in inner surfaces for the homogeneity walls

The response rules of the surface temperature with indoor air temperature have been particularly important under the air-conditioning and heating intermittent operation due to their affecting the thermal comfortable level and building energy consumption. In this study, a homogeneity wall was built and the effect of many parameters including the density, the specific heat capacity, the heat conductivity coefficient, the convective heat transfer coefficient, initial temperature and setting temperature of indoor air was analyzed on the response rules of surface temperatures by the analytical solution of the one-dimensional and unsteady heat conduction equation. And a multi-factor coupling regression formula was obtained for the time constant, which was used to evaluate the response rate of inner surface temperature.

Identifying a suitable heat setting temperature to optimize the elastic performances of cotton spandex woven fabric

PurposeThe purpose of this paper is to facilitate the production of cotton spandex woven fabric with some user-friendly properties like wearer comfort, super stretch and elasticity. The findings could contribute to ease spandex production and to optimize its property of elasticity. Stretch or a super stretch property is generally desirable, as it can increase the comfort level of those who wear it. In this experiment, the difficulties which were identified while manufacturing cotton spandex woven fabric resolved after identification.Design/methodology/approachIn this experiment, three types of cotton spandex woven fabrics, with different composition and constructions, were used to find out their elastic properties. Temperature ranging from 160°C to 200°C with the machine speed of 20 to 26 MPM (meter per minute) was applied with an adjusted industrial setting with the facilities of a stenter machine to optimize the properties of cotton spandex woven fabric.FindingsThe findings establish that the temperature treatment closely compacted the elastic portions with cotton fibers, giving stability to the spandex yarn, which as a result, influenced cotton spandex woven fabric’s elastic properties, namely, stretch, growth and recovery. The consequences of temperature on cotton spandex yarns were assessed using a microscope, and the results were subsequently analyzed.Research limitations/implicationsBecause of the poor facilities in testing laboratory, only few tests with microscopic evaluation were conducted to assess the elastic performances of cotton spandex woven fabric.Practical implicationsIt is a practice-based research, and the findings could be beneficial to personnel in the textile industry, who are responsible for the manufacturing of cotton spandex woven fabric.Social implicationsThis research could enhance the wearer’s satisfaction, with some comfort elastic properties, which can have a positive influence over spandex clothing industries.Originality/valueThis research establishes that heat setting had a progressive influence on the production of cotton spandex woven fabric and for the optimization of its elastic performances. This research opens a possible way for scholars to further study in this field.

Attaining Optimum Strength of Cotton-Spandex Woven Fabric by Apposite Heat-Setting Temperature

The purpose of this research established in this paper was to optimize the strength of cotton spandex woven fabric through heat setting with the facilitates of a stenter machine with some adjusted industrial setting. Heat setting was carried out at sufficiently high temperatures with precise time and speed, so that the spandex yarn in the fabric would get set at a desired stretched dimension. Heat setting parameters were preferred to attain the optimized strength properties of cotton spandex fabric within moderately rigid limits. Heat setting reduced the spandex recovery forces to further compression or extension. Heat setting of cotton spandex fixed the spandex inside. Heat setting also condensed the spandex inside. Due to temperature application, spandex portion gripped the cotton fibers which gave stability in the internal structure of yarn. Trials were conducted in textile mills at various temperatures those were accomplished by heating the fabric at an agreed temperature. Three different nomenclature of cotton spandex fabrics having various composition were used in this experiment to find out the strength parameters. Different temperature varied from 165 °C to 195 °C with the adjusted machine speed from 21 to 25 m per minute (m/min) were applied in this experiment to the get optimum strength. Heat setting was preferably carried out at early stages of the processing zone rather than at the end to avoid yellowing effect while drying. Improper heat seating could discolor the cotton spandex with its companion fibers. Overheat could spoil the elasticity and strength of cotton spandex, therefore it was very important to adjust the temperature and speed accordingly. This experiment proved that, temperature application had an impact over the strength of cotton spandex and also it created a suitable way for the researcher to further experiment in spandex production.

Fabrication and properties of FEP fibers by melt spinning method

ABSTRACTPoly(tetrafluoroethylene-co-hexafluoropropylene) (FEP) is a copolymer of tetrafluoroethylene (TFE) and hexafluoropropylene (HFP) which not only maintains the excellent properties of polytetrafluoroethylene (PTFE) but also breaks the drawback of PTFE's hard melt-processability. In this study, FEP fibers were spun by melt spinning method using a single screw extruder. The obtained FEP fibers’ thermal and crystallization properties were investigated via DSC, XRD and DMA respectively. Results showed that FEP fibers’ melting temperature and crystallinity degree improved as the heat setting temperatures rising from 120℃ to 160℃. The melting enthalpy increased from 29.3 J/g to 31.5 J/g while the crystal temperature decreased from 233.8℃ to 232.1℃. The morphologies of FEP fiber showed that the grooves became light, and accompanied with the decrease of the fiber diameter when the nascent fiber suffered drawing.

Effect of heat-setting on the physical properties of chemically recycled polyester nonwoven fabrics

Chemically recycled polyester fibers consisting of a core and sheath layer were used to produce nonwoven fabrics for ecofriendly automotive interiors. The density and thermal shrinkage of the recycled polyester nonwoven fabrics were higher than in virgin polyester nonwoven fabrics, irrespective of the heat-setting temperature and time, but the air permeability was lower. The wicking property of the recycled polyester nonwoven fabrics decreased significantly above 180℃. The tensile stress and modulus of the recycled polyester nonwoven fabrics increased gradually with increasing heat-setting temperature. However, the strain at maximum stress of the recycled polyester nonwoven fabrics decreased rapidly. The abrasion strength of the recycled polyester nonwoven fabrics improved above a heat-setting temperature of 200℃. The impact strength of the recycled polyester nonwoven fabrics was higher than that of virgin polyester nonwoven fabrics. As the heat-setting temperatures used for the nonwoven fabrics were higher than the melting temperature of chemically recycled and virgin polyester fibers, thermal bonding occurred between fibers. The lightness of the recycled polyester nonwoven fabrics decreased with increased heat-setting temperature and time. The recycled polyester nonwoven fabrics also showed slight yellowing. The thermal bonding between the fibers in the recycled polyester nonwoven fabrics was generated at a lower heat-setting temperature than for virgin polyester nonwoven fabrics, and therefore it is considered that under more relaxed heat treatment conditions, the recycled polyester nonwoven fabrics would show a performance similar to that of the virgin ones.