Investigation of the Thermal Properties of Different Grades Polyamide 12 (PA12) in Improving Laser Sintering Process (SLS)

2014 ◽  
Vol 548-549 ◽  
pp. 294-296 ◽  
Author(s):  
Yusoff Way ◽  
D.T. Pham ◽  
K.D. Dotchev
Keyword(s):  
Glass Transition ◽  
Thermal Properties ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Melting Temperature ◽  
Crystallization Temperature ◽  
Selective Laser Sintering ◽  
Laser Sintering ◽  
Sintering Process ◽  
Melt Flow Rate

Selective Laser Sintering (SLS) is a combined technology of computer and laser to produce complex 3D prototypes directly from CAD modeling. One of the main advantages of employing this technology is that the non-sintered powder can be recycled and reused for another fabrication. However, the fabricated part could be affected by rough and unacceptable surface texture. As a result, the parts may have to be scrapped and the build has to be repeated with a higher ratio of new material. This paper presents an experimental study of the thermal properties of new and recycled of PA12 powder in the Laser Sintering process. The influence of melting temperature, glass transition temperature and crystallization temperature on these properties is investigated. The experimental results have shown that PA12 powder with high melt flow rate, low melting temperature, low glass transition temperature and low degree of crystallization temperature could improve the sintering process.

Study on the Crystallization Activation Energy of Poly (L-lactic acid) Nucleated with P-tert-butylcalix[8]arene

2018 ◽  
Vol 26 (2) ◽  
pp. 169-175
Author(s):  
Yaoqi Shi ◽  
Liang Wen ◽  
Zhong Xin
Keyword(s):  
Activation Energy ◽  
Lactic Acid ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Crystallization Temperature ◽  
Nucleating Agent ◽  
Crystallization Activation Energy ◽  
Temperature Range ◽  
Chain Mobility

The crystallization activation energy (Δ E) of a polymer comprises the nucleation activation energy Δ F and the transport activation energy Δ E*. In this paper, the Δ E of poly (L-lactic acid) (PLLA) nucleated with nucleating agent p- tert-butylcalix[8]arene (tBC8) was calculated. The results showed that the Δ E of nucleated PLLA was 165.97 kJ/mol, which is higher than that of pure PLLA. The reason why Δ E of PLLA increased when incorporating nucleating agent was studied. The increment of glass transition temperature ( Tg) for nucleated PLLA revealed that the polymer chain mobility was restricted by tBC8, which was considered as the reason for the increase of Δ E*. Further, polyethylene glycol (PEG) was added to improve the chain mobility, thus eliminated the variation of the transport activation energy Δ E* caused by tBC8. Then the effect of the increment of crystallization temperature range on the increase of Δ F was also taken into consideration. It was concluded that both decreasing the mobility of chain segments and increasing the crystallization temperature range caused an increase of Δ E for PLLA/tBC8.

Thermal Properties of Bi2O3-B2O3-ZnO Glass System

2006 ◽  
Vol 510-511 ◽  
pp. 578-581 ◽  
Author(s):  
Yu Jin Kim ◽  
Seong Jin Hwang ◽  
Hyung Sun Kim
Keyword(s):  
Glass Transition ◽  
Thermal Properties ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Lead Oxide ◽  
Lead Free ◽  
Oxide Glasses ◽  
Glass Formation Region ◽  
Formation Region ◽  
Lower Glass Transition Temperature

Oxide glasses having lower glass transition temperature are widely used in electric devices. The oxide glasses usually contain lead oxide. Recently, lead oxide glasses have been replaced with lead-free oxide glasses because of the environmental pollution. We investigated the thermal properties and the glass formation region in the Bi2O3-B2O3-ZnO ternary system. The results showed that the ratio of Tg/Tl of the bismate glasses is around 0.55, which is lower than the value of ratio 0.67, the two-third rule (Tg/ Tl=2/3)

The Impact of Employing Different Quality PA2200 Powder Grades to Shrinkage on Sintered Part in Selective Laser Sintering Process

2015 ◽  
Vol 789-790 ◽  
pp. 126-130
Author(s):  
W.A.Y. Yusoff ◽  
D.T. Pham ◽  
K.D. Dotchev
Keyword(s):  
Selective Laser Sintering ◽  
Laser Sintering ◽  
Sintering Process ◽  
Melt Flow Rate ◽  
Input Material ◽  
Low Degree ◽  
Powder Properties ◽  
Plastic Parts ◽  
The Impact

One of the challenges which Laser Sintering faces is the Rapid Manufacturing of plastic parts with good consistent quality. This is due to the fact that plastic powder properties deteriorate during the long periods of time through the LS building and cooling cycles. This paper presents an experimental study of the deterioration or ageing of PA12 powder properties in the LS process. The influences of different grades of recycled PA12 powders are investigated. The main aim of this research is to develop a methodology of controlling the input material properties that will ensure consistent and good quality of the fabricated parts. From the experiment it was found that PA12 powder with high melt flow rate, low melting temperature, low glass transition temperature and low degree of crystallization temperature could improve the sintering process to produce a good Laser Sintering (LS) parts with lower shrinkage rate.

Study on Glass Transition Temperature of Polyvinylamine Hydrochloride

2011 ◽  
Vol 217-218 ◽  
pp. 1066-1069 ◽  
Author(s):  
Hong Chi Zhao ◽  
Qi Li ◽  
Li Bin Bai ◽  
Fan Huang
Keyword(s):  
Molecular Weight ◽  
Glass Transition ◽  
Thermal Properties ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Differential Scanning Calorimeter ◽  
Degradation Rate ◽  
Average Molecular Weight ◽  
Weight Average Molecular Weight ◽  
Dsc Curves

Polyvinylamine (PVAm) was synthesized by Hofmann degradation of polyacrylamide (PAM). The thermal properties of the Polyvinylamine hydrochloride (PVAm•HCl) were studied by differential scanning calorimeter (DSC). The degradation rate (a) decreased with increasing weight-average molecular weight (Mw) of PAM and decreasing amount of NaOH, and a were the better values when the concentration of PAM was 5% and the amount of NaClO was 10 mL. DSC curves showed that the glass transition temperature (Tg) of PVAm•HCl increased with increasing Mw of PAM, concentration of NaClO and decreasing concentration of NaOH. Tg of PVAm•HCl appeared the minimum value when the concentration of PAM was 5.0%.

scholarly journals Thermal and thermodynamic characterization of a dye powder from liquid turmeric extracts by spray drying

2016 ◽  
Vol 69 (1) ◽  
pp. 7845-7854 ◽  
Author(s):  
Aura Yazmin Coronel Delgado ◽  
Héctor José Ciro Velásquez ◽  
Diego Alonso Restrepo Molina
Keyword(s):  
Thermal Conductivity ◽  
Heat Capacity ◽  
Glass Transition ◽  
Thermal Properties ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Mass Loss ◽  
Spray Drying ◽  
Transient Flow ◽  
Sorption Isotherms

This study aimed to evaluate the thermodynamic properties of sorption isotherms and glass transition temperature (Tg) and the thermal properties of a dye powder obtained from turmeric extracts using spray drying. The sorption isotherms were evaluated at 15, 25 and 35 °C using the dynamic gravimetric method, wherein the isotherm data of the experiment were fit to GAB and BET models. Likewise, the Tg was measured using differential scanning calorimetry (DSC). Thermogravimetric analysis (TGA) was used to determine the mass loss, and the thermal properties (heat capacity, diffusivity and thermal conductivity) were determined using transient flow method. The results demonstrated that the GAB model best fit the adsorption data. The DSC analysis presented a glass transition temperature of 65.35 °C and a loss of volatiles at 178.07 °C. The TGA analysis indicated a considerable mass loss starting at 193 °C, resulting in degradation of the product. The thermal properties demonstrated a heat capacity of 2.45 J/g °C, a thermal conductivity of 0.164 ± 0.001 W/mK and a thermal diffusivity of 8.7x10-8 ± 0.000 m2/s.

Physical Properties of Fluoride Glasses for Ionics

2005 ◽  
Vol 480-481 ◽  
pp. 299-304 ◽  
Author(s):  
Viera Trnovcová ◽  
R.M. Zakalyukin ◽  
N.I. Sorokin ◽  
D. Ležal ◽  
P.P. Fedorov ◽  
...  
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Ionic Conductivity ◽  
Physical Properties ◽  
Crystallization Temperature ◽  
Glass Composition ◽  
Point Of View ◽  
Fluoride Glasses ◽  
Glass Compositions

The ionic conductivity and permittivity of glasses based on ZrF4, BaF2, LaF3, AlF3 and NaF (ZBLAN) or PbF2, InF3, BaF2, AlF3 and LaF3 (PIBAL) are studied. The influence of the glass composition on the glass transition temperature (Tg) and on the crystallization temperature (Tx) is reported. For all ZBLAN glasses the temperature dependencies of the ionic conductivity are close one to another (s500 = 8(2)·10-6 S/cm) and their conduction activation enthalpies are equal to 0.82(1)eV. From the point of view of the ionic conductivity, the best glass compositions are the PIBAL50 (50 m/o PbF2) and PIB45 ( 45 m/o PbF2).

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