Browse Prior Art Database

Thermally Stable & Low Tg Shape-Memory Polyarylene Composite Blend for Down Hole Sealing Applications

IP.com Disclosure Number: IPCOM000240422D
Publication Date: 2015-Jan-29
Document File: 5 page(s) / 2M

Publishing Venue

The IP.com Prior Art Database

Abstract

In the present invention, a shape memory polymer (SMP) composite is proposed that can be activated by heat over its glass transition temperature (Tg). The proposed SMP is a blend of chemically and thermally stable polymers, namely poly p-phenylene sulfide (PPS) and a substituted, self-reinforcing polyphenylene (SRP). The compatibilized and cross-linked polymer blend exhibits thermal stability up to 550F and elastomeric shape-memory property above 250F. Lower Tg (250F) and higher thermal stability of this SMP broadens the application window for using these materials for down hole sealing applications. A PPS/SRP polymer blend was melt-mixed and cured in presence of a cross-linker (sulfur) and filler (carbon black). The composite showed a single Tg around 130¢XC (266F) and elastomeric properties beyond. It was found that the stable elastomeric property with a single glass-transition behavior occurred only in the presence of carbon black which helped in compatibilizing the two polymers. The resultant composite showed enhanced temperature stability and improved mechanical properties (Young's modulus) over individual polymer blend(s) or a dry blended composite. Several papers and patents talk about shape memory properties of polyarylenes such as, polyphenylene sulfides (PPS), polyphenylene sulfones (PPSU), polyphenylene sulfoxides, polyether sulfones, substituted polyphenylenes, or other polyphenylene derivatives as well as methods of curing them with use of cross-linker(s) [1-6]. Recent publication also mentions cross-linked blends of PPS with PPSU for down hole applications [2]. However, the chemical stability of the latter blend has been questionable beyond 450F specifically due to lack of chemical stability of PPSU. Additionally, these blends seldom exhibit a single Tg; due to differences in the nature of polymers blended (amorphous vs. semi-crystalline), lack of right type and/or amount of compatibilizing agents/cross-linker(s), or the processing techniques used. This invention utilizes a blend of chemically stable and proven (up to 450F) high-temperature engineering thermoplastic (PPS) along with a new non-commercial self-reinforcing polyphenylene (SRP) polymer to create a single Tg composite system that would provide shape-memory properties at least up to 550F. The single Tg is achieved by a melt extrusion process whereby the polymers are mixed in a lab-scale twin screw extruder at temperature above individual Tg¡¦s in presence of sulfur (S) and dispersed with a filler (carbon black), which acts as a compatibilizing agent. This system is envisioned to have excellent chemical resistance due to predominance of PPS which exhibits chemical resistance to harsh down hole fluids. PPS is already used as a backup element sold under the trade name of Ryton„§ (Chevron Phillips chemical co.). The presence of rigid-rod like structure of Primospire„§ SRP (Solvay chemicals) would add stiffness/modulus as well as flexibility/elasticity to the composite system [3].

This text was extracted from a Microsoft Word document.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 51% of the total text.

Thermally Stable & Low Tg Shape-Memory Polyarylene Composite Blend

for Down Hole Sealing Applications

In the present invention, a shape memory polymer (SMP) composite is proposed that can be activated by heat over its glass transition temperature (Tg). The proposed SMP is a blend of chemically and thermally stable polymers, namely poly p-phenylene sulfide (PPS) and a substituted, self-reinforcing polyphenylene (SRP). The compatibilized and cross-linked polymer blend exhibits thermal stability up to 550F and elastomeric shape-memory property above 250F. Lower Tg (250F) and higher thermal stability of this SMP broadens the application window for using these materials for down hole sealing applications.

A PPS/SRP polymer blend was melt-mixed and cured in presence of a cross-linker (sulfur) and filler (carbon black). The composite showed a single Tg around 130¢XC (266F) and elastomeric properties beyond. It was found that the stable elastomeric property with a single glass-transition behavior occurred only in the presence of carbon black which helped in compatibilizing the two polymers. The resultant composite showed enhanced temperature stability and improved mechanical properties (Young's modulus) over individual polymer blend(s) or a dry blended composite. Several papers and patents talk about shape memory properties of polyarylenes such as, polyphenylene sulfides (PPS), polyphenylene sulfones (PPSU), polyphenylene sulfoxides, polyether sulfones, substituted polyphenylenes, or other polyphenylene derivatives as well as methods of curing them with use of cross-linker(s) [1-6]. Recent publication also mentions cross-linked blends of PPS with PPSU for down hole applications [2]. However, the chemical stability of the latter blend has been questionable beyond 450F specifically due to lack of chemical stability of PPSU. Additionally, these blends seldom exhibit a single Tg; due to differences in the nature of polymers blended (amorphous vs. semi-crystalline), lack of right type and/or amount of compatibilizing agents/cross-linker(s), or the processing techniques used. This invention utilizes a blend of chemically stable and proven (up to 450F) high-temperature engineering thermoplastic (PPS) along with a new non-commercial self-reinforcing polyphenylene (SRP) polymer to create a single Tg composite system that would provide shape-memory properties at least up to 550F. The single Tg is achieved by a melt extrusion process whereby the polymers are mixed in a lab-scale twin screw extruder at temperature above individual Tg¡¦s in presence of sulfur (S) and dispersed with a filler (carbon black), which acts as a compatibilizing agent. This system is envisioned to have excellent chemical resistance due to predominance of PPS which exhibits chemical resistance to harsh down hole fluids. PPS is already used as a backup element sold under the trade name of Ryton„§ (Chevron Phillips chemical co.). The pres...