Low-Pressure Carbon Dioxide Enhanced Polymer Chain Mobility below the Bulk Glass Transition Temperature

2007 ◽  
Vol 40 (4) ◽  
pp. 1108-1111 ◽  
Author(s):  
Yong Yang ◽  
Mark Ming-Cheng Cheng ◽  
Xin Hu ◽  
Dehua Liu ◽  
Richard J. Goyette ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Polymer Chain ◽  
Low Pressure ◽  
Bulk Glass ◽  
Chain Mobility

Measuring the glass-transition temperature in electrospun polyvinyl alcohol fibers using AFM nanomechanical bending tests

2009 ◽  
Vol 1185 ◽  
Author(s):  
Wei Wang ◽  
Asa H. Barber
Keyword(s):  
Glass Transition ◽  
Elastic Modulus ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Polyvinyl Alcohol ◽  
Polymer Chain ◽  
Fiber Diameter ◽  
Bending Tests ◽  
Chain Mobility ◽  
Pva Fiber

AbstractThe glass transition of individual electrospun PVA fibers was found using an AFM fiber bending technique within a heated chamber. A considerably loss in the measured elastic modulus was observed with temperature when the glass transition temperature was reached. The glass transition temperature was observed to decrease as the electrospun PVA fiber diameter decreased, indicating diameter dependent enhanced polymer chain mobility.

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.

Surface Mobile Layer of Polystyrene Film below Bulk Glass Transition Temperature

2001 ◽  
Vol 34 (18) ◽  
pp. 6164-6166 ◽  
Author(s):  
Daisuke Kawaguchi ◽  
Keiji Tanaka ◽  
Atsushi Takahara ◽  
Tisato Kajiyama
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Bulk Glass ◽  
Polystyrene Film

The Effect of Methylene Diphenyl Diisocyanate on the Nonisothermal Properties of Polylactic Acid/Elaeis guineensis Fibres Biocomposites

2013 ◽  
Vol 594-595 ◽  
pp. 823-827
Author(s):  
Luqman Hakim Ahmad Subri ◽  
Sakinah Mohd Alauddin ◽  
Senawi Rosman
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Polylactic Acid ◽  
Elaeis Guineensis ◽  
Fibre Surface ◽  
Degree Of Crystallinity ◽  
Chain Mobility ◽  
Methylene Diphenyl Diisocyanate ◽  
The Degree Of Crystallinity

Biocomposites demands are significantly rising due to environmental regulations and concerns. However, incompatibility between the fibre and matrix is a major setback that diminishes the biocompostie properties. Therefore in this work, methylene diphenyl diisocynate (MDI) compatibilizers were used together with fibre surface treatment in order to increase compatibility between polylactic acid (PLA) and Elaeis Guineensis Fibres (EGF) biocomposite. Nonisothermal properties were investigated and it was found that, MDI increased compatibility of the PLA and EGF which led to the restriction of chain movements in the biocomposite. This restriction in chain mobility caused an increase the glass transition temperature and crystallization temperature and also reduced the degree of crystallinity.

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