Thermal and mechanical properties of polyurethane-diacetylene segmented copolymers. I. Molecular weight and annealing effects

1990 ◽  
Vol 23 (4) ◽  
pp. 1005-1016 ◽  
Author(s):  
R. A. Nallicheri ◽  
Michael F. Rubner
Keyword(s):  
Mechanical Properties ◽  
Molecular Weight ◽  
Thermal And Mechanical Properties ◽  
Segmented Copolymers ◽  
Annealing Effects

Weldability of pipe grade polyethylenes as realized from thermal and mechanical properties assessments

2016 ◽  
Vol 36 (8) ◽  
pp. 853-860 ◽  
Author(s):  
Vahabodin Goodarzi ◽  
Zahed Ahmadi ◽  
Mohammad Reza Saeb ◽  
Farkhondeh Hemmati ◽  
Mehdi Ghaffari ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Thermal Analysis ◽  
Molecular Weight ◽  
Aging Process ◽  
Pipe Production ◽  
Lamellar Thickness ◽  
Thermal And Mechanical Properties ◽  
Scanning Calorimetry ◽  
Injection Molded ◽  
The One

Abstract Since polyethylene (PE) has been widely accepted for the production of high-pressure fluid conveying pipelines, studies devoted to weldability of PE connections were always of major importance. In this study, two industrial PE grades designed for pipe production, namely PE80 and PE100, were injection molded, cut, and then welded as PE100-PE100, PE100-PE80, and PE80-PE80. The heat-welded joints were assessed by differential scanning calorimetry and tensile measurements. The results obtained from thermal and mechanical analyses were compared with equivalents for aged samples. Thermal analysis revealed that the melting point of the PE100-PE100 sample is obviously larger than the one for the PE80-PE80 joint, for the PE80 chains deteriorate the crystallization of PE100. Further, the PE80-PE80 sample showed the lowest lamellar thickness and crystalline molecular weight among the studied joints. The aging process was found to increase lamellar thickness and molecular weight, though in the PE100-PE100 sample such quantities very limitedly increased. The yield stress of aged joints was higher than that for just-prepared samples, while an inverse trend was seen for strain at break. From a practical viewpoint, the PE100-PE100 welds offer better properties.

Titanium 6/4 Single Lap Shear Adhesive Performance of Polyimide Homopolymers and Poly(Siloxane Imide) Segmented Copolymers

1989 ◽  
Vol 153 ◽  
Author(s):  
T. H. Yoon ◽  
C. A. Arnold ◽  
J. E. McGrath
Keyword(s):  
Mechanical Properties ◽  
Residual Stress ◽  
High Performance ◽  
Amic Acid ◽  
Thermal Cyclization ◽  
Thermal And Mechanical Properties ◽  
Space Applications ◽  
Aromatic Polyimides ◽  
Segmented Copolymers ◽  
Lap Shear

Polyimides are attractive candidates for advanced electronic and space applications due to their high performance thermal and mechanical properties. However, the typical intractability and insolubility of polyimides has been a disadvantage. Utilization of the soluble intermediate amic acid can, to some extent, circumvent this problem. However, drawbacks to this approach include the hydrolytic instability of the amic acid and the liberation of water during its subsequent thermal cyclization. Residual stress build-up at the imide-substrate interface may occur due to swelling and drying cycles caused by the loss of water and solvent. In addition, the liberation of volatiles from a polyimide adhesive or coating can lead to the creation of voids which may significantly detract from mechanical properties. Polymeric adhesives must flow in order to provide good wetting of adherend surfaces and consolidation of the bond components. Thus, fully imidized, melt and solution processable, high Tg aromatic polyimides are of great interest.

scholarly journals Properties Enhancement of High Molecular Weight Polylactide Using Stereocomplex Polylactide as a Nucleating Agent

Polymers ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 1725
Author(s):  
Purba Purnama ◽  
Muhammad Samsuri ◽  
Ihsan Iswaldi
Keyword(s):  
Mechanical Properties ◽  
Molecular Weight ◽  
Crystallization Behavior ◽  
Testing Machine ◽  
Nucleating Agent ◽  
Mechanical And Thermal Properties ◽  
Nucleating Agents ◽  
Thermal And Mechanical Properties ◽  
X Ray ◽  
Universal Testing

As one of the most attractive biopolymers nowadays in terms of their sustainability, degradability, and material tune-ability, the improvement of polylactide (PLA) homopolymer properties by studying the utilization of stereocomplex polylactide (s-PLA) effectively and efficiently is needed. In this sense, we have studied the utilization of s-PLA compared to poly D-lactide (PDLA) homopolymers as a nucleating agent for PLA homopolymers. The mechanical and thermal properties and crystallization behavior of PLA homopolymers in the presence of nucleating agents have been evaluated using a universal testing machine, differential scanning calorimeter, and X-ray diffractometer instruments, respectively. PDLA and s-PLA materials can be used to increase the thermal and mechanical properties of poly L-lactide (PLLA) homopolymers. The s-PLA materials increased the mechanical properties by increasing crystallinity of the PLLA homopolymers. PLLA/s-PLA enhanced mechanical properties to a certain level (5% s-PLA content), then decreased them due to higher s-PLA materials affecting the brittleness of the blends. PDLA homopolymers increased mechanical properties by forming stereocomplex PLA with PLLA homopolymers. Non-isothermal and isothermal evaluation showed that s-PLA materials were more effective at enhancing PLLA homopolymer properties through nucleating agent mechanism.

Influence of the molecular weight on the thermal and mechanical properties of ethylene/norbornene copolymers

2003 ◽  
Vol 89 (12) ◽  
pp. 3358-3363 ◽  
Author(s):  
Nikos Ekizoglou ◽  
Knut Thorshaug ◽  
María L. Cerrada ◽  
Rosario Benavente ◽  
Ernesto Pérez ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Molecular Weight ◽  
Thermal And Mechanical Properties

scholarly journals Thermal and Mechanical Properties of Vinyltrimethoxysilane (VTMOS) Crosslinked High Molecular Weight Polyethylene (HMWPE)

2017 ◽  
Vol 20 (5) ◽  
pp. 1332-1339 ◽  
Author(s):  
Marisa Cristina Guimarães Rocha ◽  
Lorena Rodrigues da Costa Moraes ◽  
Norberto Cella
Keyword(s):  
Mechanical Properties ◽  
Molecular Weight ◽  
High Molecular Weight ◽  
Thermal And Mechanical Properties
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