Thermal behaviour of heat treated polyester knitted fabrics

2020 ◽  
Vol 24 (4) ◽  
pp. 305-319
Author(s):  
Henadeera Arachchige Ayomi Enoka Perera ◽  
Wilathgamuwage Don Gamini Lanarolle
Keyword(s):  
Effective Temperature ◽  
Heat Treatments ◽  
Thermal Shrinkage ◽  
Scanning Calorimetry ◽  
Knitted Fabrics ◽  
Heat Setting ◽  
Content Type ◽  
Analytical Technique ◽  
Shrinkage Behaviour ◽  
Heat Treated

Purpose Thermoplastic 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/approach In 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. Findings Heat 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/value The 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.

Comparative study on the thermal shrinkage behaviour of polyester yarn and its plain knitted fabrics

2020 ◽  
Vol 111 (12) ◽  
pp. 1755-1765
Author(s):  
Henadeera Arachchige Ayomi Enoka Perera ◽  
Wilathgamuwage Don Gamini Lanarolle
Keyword(s):  
Comparative Study ◽  
Thermal Shrinkage ◽  
Polyester Yarn ◽  
Knitted Fabrics ◽  
Shrinkage Behaviour

Precipitation Behaviour and Mechanical Properties during Short-Term Heat Treatment for Tailor Heat Treated Profiles (THTP) of Aluminium Alloy 6060 T4

2016 ◽  
Vol 877 ◽  
pp. 400-406 ◽  
Author(s):  
Hannes Fröck ◽  
Matthias Graser ◽  
Benjamin Milkereit ◽  
Michael Reich ◽  
Michael Lechner ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Aluminium Alloy ◽  
Heat Treatments ◽  
Maximum Temperature ◽  
Short Term ◽  
Scanning Calorimetry ◽  
Heat Treated ◽  
Precipitation Behaviour ◽  
Dissolution And Precipitation

Precipitation hardening aluminium alloys are widely used for automotive applications. To enhance the application of aluminium profiles, improved formability is needed. Tailor Heat Treated Profiles (THTP) with locally different material properties attempt to increase formability e.g. in bending processes. Tailoring of local properties is obtained by a local short-term heat treatment, dissolving the initial precipitate state (retrogression) and still allowing subsequent ageing. In the present study, the dissolution and precipitation behaviour of the aluminium alloy EN AW-6060 T4 was investigated during heating with differential scanning calorimetry (DSC). Heating curves from 20 to 600 °C with heating rates of 0.01 up to 5 K/s were recorded. Interrupted heat treatments with different maximum temperatures were performed in a deformation dilatometer. Immediately afterwards, tensile tests were carried out at room temperature. The course of the recorded mechanical properties as a function of the maximum temperature is discussed with regard to the dissolution and precipitation behaviour during heating. Finally, the aging behaviour of the investigated alloy was recorded after different typical short-term heat treatments and is discussed with reference to the DSC‐curves. The correlation of the microstructure and the mechanical properties enables the derivation of optimal parameters for the development of THTP through a local softening.

scholarly journals Scanning Rate Extension of Conventional DSCs through Indirect Measurements

Materials ◽  
2019 ◽  
Vol 12 (7) ◽  
pp. 1085 ◽  
Author(s):  
Hannes Fröck ◽  
Michael Reich ◽  
Benjamin Milkereit ◽  
Olaf Kessler
Keyword(s):  
Aluminum Alloys ◽  
Indirect Measurement ◽  
Heat Treatments ◽  
Dissolution Behavior ◽  
Heating Rates ◽  
Scanning Calorimetry ◽  
Heating And Cooling ◽  
Heat Treated ◽  
Conventional Dsc

In this work, a method is presented which allows the determination of calorimetric information, and thus, information about the precipitation and dissolution behavior of aluminum alloys during heating rates that could not be previously measured. Differential scanning calorimetry (DSC) is an established method for in-situ recording of dissolution and precipitation reactions in various aluminum alloys. Diverse types of DSC devices are suitable for different ranges of scanning rates. A combination of the various available commercial devices enables heating and cooling rates from 10−4 to 5 Ks−1 to be covered. However, in some manufacturing steps of aluminum alloys, heating rates up to several 100 Ks−1 are important. Currently, conventional DSC cannot achieve these high heating rates and they are still too slow for the chip-sensor based fast scanning calorimetry. In order to fill the gap, an indirect measurement method has been developed, which allows the determination of qualitative information, regarding the precipitation state, at various points of any heat treatment. Different rapid heat treatments were carried out on samples of an alloy EN AW-6082 in a quenching dilatometer and terminated at defined temperatures. Subsequent reheating of the samples in the DSC enables analysis of the precipitation state of the heat-treated samples. This method allows for previously un-measurable heat treatments to get information about the occurring precipitation and dissolution reactions during short-term heat treatments.

scholarly journals In vitro corrosion analyses of heat treated cobalt-chromium alloys manufactured by direct metal laser sintering

2015 ◽  
Vol 21 (1) ◽  
pp. 111-116 ◽  
Author(s):  
Frank Alifui-Segbaya ◽  
Jeffrey Lewis ◽  
Dominic Eggbeer ◽  
Robert John Williams
Keyword(s):  
Thermal Stresses ◽  
Artificial Saliva ◽  
Heat Treatments ◽  
Dental Alloys ◽  
Cobalt Chromium ◽  
Ion Release ◽  
Content Type ◽  
Heat Treated ◽  
Main Effect ◽  
Academic Review

Purpose – The purpose of this research paper is to compare corrosion data obtained from additive-manufactured heat-treated (HRx) and non-heat-treated (NHRx) cobalt-chromium (Co–Cr) alloys. Heat treatments are indicated as necessary in complex intra-oral framework production by additive manufacturing to remove accumulated thermal stresses. However, heat treatments have been linked to corrosion in cast dental alloys. Currently, there are few publications on this subject for laser-sintered dental alloys required for academic review. Design/methodology/approach – Five rectangular specimens (n = 5), each with a total surface area of 10.27 cm2, were fabricated for the two groups. Specimens were immersed in an artificial saliva solution suspended by a nylon thread for 42 days at 37°C. Readings for Co, Cr and molybdenum ions released into the solution were obtained using an atomic absorption spectrometer at 1-, 4-, 7-, 14-, 21-, 28-, 35- and 42-day intervals at a detection limit of one part per million. Test methods are in accordance with ISO 10271. Findings – Results showed a higher ion release in the HRx sample, statistically significant at 99 per cent confidence level (p < 0.01). A two-way ANOVA test conducted showed that there was a main effect of day and a main effect of finish, and there was also a significant interaction between these factors. Originality/value – The study concludes that, although ion release in both samples was within the safe level recommended by ISO for the three major alloying elements, heat treatment, indeed, contributed extensively to the reduced corrosion resistance in the laser-sintered Co–Cr alloy. Further biocompatibility tests are recommended.

3-D Characterization of Global and Local Microstructural Effects on Spall Damage in Shock Loaded FCC Metals: Experimental and Modeling

2013 ◽  
Author(s):  
A. Brown ◽  
K. Krishnan ◽  
L. Wayne ◽  
P. Peralta ◽  
S. N. Luo ◽  
...  
Keyword(s):  
Weak Link ◽  
Heat Treatments ◽  
Taylor Factor ◽  
Weak Links ◽  
Spall Damage ◽  
Heat Treated ◽  
Microstructural Effects ◽  
Global And Local ◽  
Low Pressures

Global and local microstructural weak links for spall damage were investigated using 3-D characterization in polycrystalline (PC) and multicrystalline (MC) copper samples, respectively. All samples were shocked via flyer-target plate experiments using a laser drive at low pressures (2–6 GPa). The flyer plates measured approximately 500 μm thick and 8 mm in diameter and the target plates measured approximately 1000 μm thick and 10 mm in diameter. Electron Backscattering Diffraction (EBSD) and optical microscopy were used to determine to presence of voids and relate them to the surrounding microstructure. Statistics on the strength of grain boundaries (GBs) was conducted by analyzing PC samples and collecting the misorientation across GBs with damage present, and it was found that a misorientation range of 25–50° is favorable for damage. Statistics were also taken of copper PC samples that had undergone different heat treatments and it was found that although the 25–50° range is less dominant, it is still favorable for damage nucleation. Removal of initial plastic strain via heat treatments and an increase in Σ3 CSL boundaries, indicative of strong annealing twins, also led to an increased amount of transgranular damage. 3-D X-ray tomography data were used to investigate the shape of the voids present in untreated, as received and heat treated samples. It was found that the as received sample contained a higher amount of “disk”, or, “sheet-like” voids indicative of intergranular damage, whereas the heat treated samples had a higher fraction of spherical shaped voids, indicative of transgranular damage. MC samples were used to study microstructural weak links for spall damage because the overall grain size is much larger than the average void size, making it possible to determine which GBs nucleated damage. Simulations and experimental analysis of damage sites with large volumes indicate that high Taylor factor mismatches with respect to the crystallographic grain GB normal is the primary cause for the nucleation of damage at a GB interface and a low Taylor factor along the shock direction in either grain drives void growth perpendicular to the GB. Cases where experimental results show damage and simulation results show no damage are attributed to the presence of an intrinsic microstructural weak link, such as an incoherent twin boundary.

Study in performance and morphology of polyamide 12 produced by selective laser sintering technology

2018 ◽  
Vol 24 (5) ◽  
pp. 813-820 ◽  
Author(s):  
Junjie Wu ◽  
Xiang Xu ◽  
Zhihao Zhao ◽  
Minjie Wang ◽  
Jie Zhang
Keyword(s):  
Selective Laser Sintering ◽  
Polarized Light ◽  
Chain Scission ◽  
High Energy ◽  
Laser Sintering ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Content Type ◽  
X Ray ◽  
Polyamide 12

Purpose The purpose of this paper is to investigate the effect of selective laser sintering (SLS) method on morphology and performance of polyamide 12. Design/methodology/approach Crystallization behavior is critical to the properties of semi-crystalline polymers. The crystallization condition of SLS process is much different from others. The morphology of polyamide 12 produced by SLS technology was investigated using scanning electron microscopy, polarized light microscopy, differential scanning calorimetry, X-ray diffraction and wide-angle X-ray diffraction. Findings Too low fill laser power brought about bad fusion of powders, while too high energy input resulted in bad performance due to chain scission of macromolecules. There were three types of crystal in the raw powder material, denoted as overgrowth crystal, ring-banded spherulite and normal spherulite. Originality/value In this work, SLS samples with different sintering parameters, as well as compression molding sample for the purpose of comparison, were made to study the morphology and crystal structure of sintered PA12 in detail.

Computational contact mechanics analysis of laterally graded orthotropic half-planes

2017 ◽  
Vol 14 (2) ◽  
pp. 145-154 ◽  
Author(s):  
Onur Arslan
Keyword(s):  
Contact Mechanics ◽  
Solution Method ◽  
Solution Procedure ◽  
Engineering Applications ◽  
Linear Solution ◽  
Content Type ◽  
Analytical Technique ◽  
Computational Contact Mechanics ◽  
Mechanics Analysis ◽  
Contact Response

Purpose Frictional sliding contact problems between laterally graded orthotropic half-planes and a flat rigid stamp are investigated. The presented study aims at guiding engineering applications in the prediction of the contact response of orthotropic laterally graded members. Design/methodology/approach The solution procedure is based on a finite element (FE) approach which is conducted with an efficient FE analysis software ANSYS. The spatial gradations of the orthotropic stiffness constants through the horizontal axis are enabled utilizing the homogeneous FE approach. The Augmented Lagrangian contact algorithm is used as an iterative non-linear solution method in the contact analysis. Findings The accuracy of the proposed FE solution method is approved by using the comparisons of the results with those computed using an analytical technique. The prominent results indicate that the surface contact stresses can be mitigated upon increasing the degree of orthotropy and positive lateral gradations. Originality/value One can infer from the literature survey that, the contact mechanics analysis of orthotropic laterally graded materials has not been investigated so far. In this study, an FE method-based computational solution procedure for the aforementioned problem is addressed. The presented study aims at guiding engineering applications in the prediction of the contact response of orthotropic laterally graded members. Additionally, this study provides some useful points related to computational contact mechanics analysis of orthotropic structures.

Effect of Heat Setting Methods on Structures and Properties of High Strength Polyvinyl Alcohol Fibre

2015 ◽  
Vol 815 ◽  
pp. 643-648
Author(s):  
Yin Zhu ◽  
Jiong Xin Zhao
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Polyvinyl Alcohol ◽  
Setting Time ◽  
High Strength ◽  
Single Fibre ◽  
X Ray Diffraction ◽  
Heat Setting ◽  
Heat Treated ◽  
Setting Process

The effect of heat setting methods on the structures and mechanical properties of high strength polyvinyl alcohol (PVA) fibre is studied in this article. The microstructure and mechanical properties of heat treated PVA fibre is investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD), and single fibre electronic tensile strength tester. Results show that the heat setting method with constant tension is a good heat setting method which can largely enhance the tensile strength of PVA fibre. During the heat setting process, the mechanical properties of PVA fibre are greatly affected by the temperature, tension and setting time. When the temperature is 220°C, tension is 5cN/dtex and setting time is 90sec, the tensile strength of PVA fibre increases from 12.0cN/dtex to 16.4cN/dtex in compare with the PVA fibre without heat setting

How the creative mindset affects entrepreneurial success in the tourism sector: the mediating role of innovation capability

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Natthawut Yodchai ◽  
Pham Thi Minh Ly ◽  
Lobel Trong Thuy Tran
Keyword(s):  
Tourism Industry ◽  
Innovation Capability ◽  
Entrepreneurial Success ◽  
Content Type ◽  
Analytical Technique ◽  
Mediating Role ◽  
Business Goals ◽  
Tourism Sector ◽  
And Performance

Purpose This study aims to adopt implicit theory (IPT) to develop a creative mindset model and drive entrepreneurial success through innovation capability (IC). Design/methodology/approach Expert interviews were conducted using a questionnaire protocol. This study investigated the effect of the creative mindset on entrepreneurial success through IC, using a partial least squares analytical technique and by interviewing 176 Thai business owners. Findings The creative mindset drove entrepreneurial success through IC. Entrepreneurs possessing a growth mindset reflected and drove success directly or through IC. Although, those with a strong, fixed mindset did not significantly affect entrepreneurial success, they could drive success through IC. Research limitations/implications This study provides further insight into the probable causation of how the creative mindset and IC affect tourism entrepreneurs’ success. Accordingly, this study contributes a framework to help entrepreneurs’ creativity and performance in achieving their business goals. Originality/value Drawing from IPT, this study empirically tests and substantiates the mediating role of IC in the relationship between the creative mindset and entrepreneurial success in the tourism industry. This study can help entrepreneurs increase their managerial effectiveness.

Dlts-Studies on the “New Oxygen Donor” in Heat Treated and Hydrogenated CZ-Grown SI

1985 ◽  
Vol 59 ◽  
Author(s):  
Karlheinz Hölzlein ◽  
G. Pensl ◽  
M. Schulz ◽  
N. M. Johnson
Keyword(s):  
Low Temperature ◽  
Heat Treatments ◽  
Experimental Results ◽  
Interface Model ◽  
Trap States ◽  
High Concentration ◽  
Oxygen Donor ◽  
Heat Treated ◽  
Processing Steps

ABSTRACTCz-grown Si samples containing a high concentration of oxygen are investigated after various processing steps by DLTS. Heat treatments ranging from 500°C–1000°C are performed to study the formation and annihilation of the “New Oxygen Donor” (ND) traps. Hydrogenation at low temperature leads to a reduction of the ND trap states. The experimental results confirm the “SiOx Interface Model” which assumes two differing types of interfacerelated states.

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