Adhesive and composite properties of LARCTM-8515 polyimide

1995 ◽  
Vol 7 (1) ◽  
pp. 11-21 ◽  
Author(s):  
B J Jensen ◽  
T H Hou ◽  
S P Wilkinson
Keyword(s):  
Composite Laminates ◽  
High Performance ◽  
Molar Ratio ◽  
Aromatic Polyimide ◽  
Aerospace Applications ◽  
Short Beam ◽  
Beam Shear ◽  
Open Hole ◽  
Biphenyltetracarboxylic Dianhydride ◽  
Langley Research Center

LARCTM-8515 (Langley Research Center-8515) is an aromatic polyimide based on 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA) and an 85:15 molar ratio of 3,4'-oxydianiline (3,4'-ODA) and 1,3-bis(3-amnophenoxy)benzene (APB). This material is currently under evaluation as an adhesive and composite matrix resin for use in high-performance aerospace applications. The synthesis and development of the copolymer as well as studies of the effect of molecular weight on properties will be discussed. LARCTM-8515 has been evaluated as an adhesive, and titanium to titanium tensile shear strengths will be presented. Unidirectional prepreg was' made utilizing the Langley multipurpose tape machine. and the thermal and rheological properties and the solvent/volatile depletion rates of the poly(amide acid)/NMP resin system were determined. This information was used to successfully design a moulding cycle for composite preparation. Composite laminates were moulded under 200 psi, which consistently yielded good consolidation quality as measured by C-scan, acid digestion and optical photomicrography. Composite mechanical properties measured included short-beam shear strength and flexural strength and modulus at RT, 93, 150 and 177C. and compression strength (ITRI) and open hole compression (OHC) strength at RT and 177 C (wet).

Processing and Properties of IM7/LARCTM-SCI Composite

1996 ◽  
Vol 8 (2) ◽  
pp. 169-184 ◽  
Author(s):  
T H Hou ◽  
R G Bryant
Keyword(s):  
Flexural Strength ◽  
Compression Strength ◽  
Composite Laminates ◽  
Thermoplastic Composites ◽  
Longitudinal Tensile Strength ◽  
Molecular Weights ◽  
Short Beam ◽  
Beam Shear ◽  
Open Hole ◽  
Langley Research Center

LARCTM-SCI (Langley Research Center - Semi-Crystaline polyImide) is an aromatic polyimide based on 3,4′-oxydianiline and 3,3′,4,4′-biphenyl tetracarboxylic dianhydride. This polyimide was synthesized and evaluated for use as a neat resin and a matrix resin for advanced composites. Three 30% w/w solids polyamic acid/ N-methypyrrolidone solutions were prepared using 2, 3 and 4% stoichiometric imbalances end-capped with phthalic anhydride to provide polyimides with theoretical number average molecular weights of approximately 22 800, 15 100 and 11 400 g mol−1 respectively. Unidirectional IM7 carbon fibre prepreg was prepared from these three resins using the Langley multipurpose tape machine. Thermal and rheological properties and the solvent/volatile depletion rates along with crystallization kinetics were characterized for the resin scraps taken from the prepreg tapes. Processing characteristics of the LARCTM-SCI resin were thoroughly understood from these results, and a workable moulding cycle was designed for this composite. Composite laminates were moulded at 410 °C at either 200 or 300 psi, which consistently yielded good consolidation and high-quality panels as measured by C-scan, acid digestion and optical photomicrography. The composite mechanical properties were also obtained. Short beam shear strength was 15 ksi at RT. Longitudinal flexural strength was 295 ksi at RT and 200 ksi at 177 °C. Excellent fracture toughness of 6.9 in-lb/in2 was obtained. Excellent values of transverse flexural strength and longitudinal tensile strength indicated a good translation of fibre properties into the composite. Un-notched longitudinal compression strength of 163 ksi was comparable to typical thermoplastic composites. An open hole compression strength of 55 ksi suggested good damage tolerance for this composite.

IM7/LARC™ MPEI-1 Polyimide Composites

1998 ◽  
Vol 10 (2) ◽  
pp. 181-192 ◽  
Author(s):  
T H Hou ◽  
R J Cano ◽  
B J Jensen
Keyword(s):  
Mechanical Properties ◽  
High Performance ◽  
Elevated Temperatures ◽  
Flexural Modulus ◽  
Temperature Dependent ◽  
Aromatic Polyimide ◽  
Longitudinal Tensile Strength ◽  
Short Beam ◽  
Beam Shear ◽  
Langley Research Center

LARC™ MPEI-1 (Langley Research Center™ modified phenylethynyl imide-1) phenylethynyl containing aromatic polyimide, is based on the reaction of biphenyl dianhydride (BPDA), 3,4′-oxydianiline (3,4′-ODA), 1,3-bis(3-aminophenoxy)benzene (APB), 2,4,6-triaminopyrimidine (TAP) and 4-phenylethynyl phthalic anhydride (PEPA), presumably resulting in a mixture of linear, branched and star shaped phenylethynyl containing imides which was evaluated as a matrix for high-performance composites. The poly(amid acid) solution of MPEI-1 in N-methypyrrolidinone was synthesized at 35% and 42% solids. Unidirectional prepreg was fabricated from these solutions and Hercules IM7 carbon fibre utilizing NASA-Langley’s multipurpose prepreg machine. The temperature-dependent volatile depletion rates, thermal crystallization behaviour and resin rheology were characterized. Based on this information, a composite moulding cycle was developed which yielded well consolidated, voidfree laminates. Composite mechanical properties such as short beam shear strength, longitudinal and transverse flexural strength and flexural modulus, longitudinal tensile strength and notched and unnotched compression strengths were measured at room temperature (RT) and elevated temperatures. These mechanical properties are compared with those of IM7/LARC™ PETI-5 composites.

Processing and Properties of IM7/LARC™ -Si Polyimide Composites

1997 ◽  
Vol 9 (4) ◽  
pp. 437-448 ◽  
Author(s):  
T H Hou ◽  
R G Bryant
Keyword(s):  
Fracture Toughness ◽  
Elevated Temperatures ◽  
Flexural Modulus ◽  
Longitudinal Tensile Strength ◽  
Compression After Impact ◽  
Short Beam ◽  
Beam Shear ◽  
Open Hole ◽  
Biphenyltetracarboxylic Dianhydride ◽  
Langley Research Center

LARC™-SI (NASA Langley Research Center-Soluble Imide) is an aromatic thermoplastic polyimide. LARC™-SI is synthesized from equimolar amounts of oxydiphthalic anhydride (ODPA), 3, 3′, 4, 4′-biphenyltetracarboxylic dianhydride (BPDA) and the equivalent amount of 3, 4′-oxydianiline (3, 4′-ODA). Phthalic anhydride (PA) was used as an endcapper to control molecular weight. A 30% solid LARC™-SI solution (in NMP/Xylene: 9/1 v/v) with 3% stoichiometric imbalance was made into unidirectional long-fibre-reinforced prepregs. Thermal properties, volatile depletion behaviour and resin rheology were thoroughly characterized. Using this information, two composite moulding cycles were developed that consistently yielded well consolidated, void-free laminates. Composite mechanical properties such as short-beam shear strength, longitudinal and transverse flexural strength and flexural modulus, longitudinal tensile strength and notched and un-notched compression strengths, fracture toughness, open-hole compression strength and compression after impact (CAI) strength were measured at room temperature (RT) and elevated temperatures. LARC™-SI composite exhibited very good toughness and damage tolerance. The interlaminar fracture toughness and the CAI strength were measured at 1.72 kJ m−2 at 35.2 GPa respectively.

IM7/LARC™-IAX-3 Polyimide Composites

1998 ◽  
Vol 10 (2) ◽  
pp. 193-206 ◽  
Author(s):  
T H Hou ◽  
T L St Clair
Keyword(s):  
Mechanical Properties ◽  
High Performance ◽  
Elevated Temperatures ◽  
Flexural Modulus ◽  
Longitudinal Tensile Strength ◽  
Molecular Weights ◽  
Short Beam ◽  
Beam Shear ◽  
Carrier Solvent ◽  
Langley Research Center

LARC™-IAX-3 (Langley Research Center™-improved adhesive experimental resin-3) aromatic polyimide, based on oxydiphthalic anhydride, 3,′4-oxydianiline (3,′4-ODA) and 1,4-phenylenediamine ( p-PDA), was evaluated as a matrix for high-performance composites. Four poly(amide acid) solutions in either N-methypyrrolidone or γ-butyrolactone, end-capped with phthalic anhydride to various theoretical molecular weights, were synthesized. Unidirectional prepreg was fabricated from each of the four resins utilizing NASA-Langley’s multipurpose prepreg machine. The temperature-dependent volatile depletion rates, the thermal crystallization behaviour and the resin rheology were characterized. Based on this information, a composite moulding cycle was developed which consistently yielded well consolidated void-free laminate parts. Composite mechanical properties such as short beam shear strength, longitudinal and transverse flexural strength and flexural modulus, longitudinal tensile strength and notched and unnotched compression strengths were measured at room temperature (RT) and elevated temperatures. Similar properties were obtained independent of the carrier solvent used during matrix resin synthesis. These mechanical properties were superior to those previously measured for IM7/LARC™-IA and IM7/LARC™-IAX composites. The enhanced mechanical properties were attributed to the substitution of 25% 3,′4-ODA by p-PDA in the LARC™-IA imide backbones.

LaRC ™-SI: A Soluble Aromatic Polyimide

1996 ◽  
Vol 8 (4) ◽  
pp. 607-615 ◽  
Author(s):  
Robert G Bryant
Keyword(s):  
Softening Point ◽  
High Performance ◽  
Adhesive Properties ◽  
Aromatic Polyimide ◽  
Lap Shear ◽  
Biphenyltetracarboxylic Dianhydride ◽  
Langley Research Center ◽  
Hot Melt ◽  
Poly Imide ◽  
Solubility Characteristic

LaRC™-SI (NASA Langley Research Center-Soluble poly Imide) is a wholly aromatic, high-performance thermoplastic with a unique combination of physical, mechanical and adhesive properties. LaRC™-SI is synthesized from equimolar amounts of the dianhydrides 4, 4′-oxydiphthalic anhydride (ODPA) and 3, 3′, 4, 4′-biphenyltetracarboxylic dianhydride (BPDA); 3, 4′-oxydianiline (3, 4′-ODA) and phthalic anhydride (PA) as an endcapping reagent. The most unique property of LaRC™-SI is its initial solubility in conventional high-boiling aprotic solvents. However, when exposed to temperatures above its softening point of 250 °C it becomes insoluble yet retains its melt processability. This allows LaRC™-SI to be solution processed as both a polyamic acid and a polyimide. In addition to this solubility characteristic and high softening point, LaRC™-SI is extremely tough and fracture resistant with G1c and K1c values of 4.6 kJ m−2 and 4.4 MN m−3/2 respectively. As a melt extruded film, LaRC™-SI has been used as a hot melt adhesive to bond titanium and aluminium with lap shear strengths for titanium and cleavage strengths for aluminium exceeding 43 MPa and 16.9 MPa respectively at 23 °C.

A Hybrid Actuation System (HYBAS) and Aerospace Applications

2005 ◽  
Vol 888 ◽  
Author(s):  
Ji Su ◽  
Tian-Bing Xu ◽  
Shujun Zhang ◽  
Thomas R. Shrout ◽  
Qiming Zhang
Keyword(s):  
Single Crystal ◽  
High Performance ◽  
Theoretical Modeling ◽  
Synthetic Jet ◽  
Aerospace Applications ◽  
Actuation System ◽  
Electromechanical Responses ◽  
Control Technologies ◽  
Langley Research Center ◽  
Hybrid Actuation

ABSTRACTAn electroactive polymer-ceramic hybrid actuation system (HYBAS) has been developed at NASA Langley Research Center. The system demonstrates significantly-enhanced electromechanical performance by cooperatively utilizing advantages of a combination of electromechanical responses of an electroative polymer (EAP), and an electroactive ceramic single crystal, PZN-PT single crystal. The electroactive elements are driven by a single power source. Recently, a modification of HYBAS has been made to increase the capability of air driving for synthetic jet devices (SJ) used in aerodynamic control technologies. The dependence of the air driving capability of the modified HYBAS on the configuration of the actuating device has been investigated. For this particular application, the modified HYBAS demonstrated a 50% increase in the volume change in the synthetic jet air chamber, as compared with that of the HYBAS without the modification. The theoretical modeling of the performances of the HYBAS is in good agreement with experimental observation. The consistence between the theoretical modeling and experimental test make the design concept an effective route for the development of high performance actuating devices for many applications. The theoretical modeling, fabrication of the HYBAS and the initial experimental results will be presented and discussed.

Mechanical Performance of Carbon/Epoxy Composites with Embedded Polymeric Films

2007 ◽  
Vol 334-335 ◽  
pp. 469-472 ◽  
Author(s):  
Ben Qi ◽  
Michael Bannister
Keyword(s):  
Composite Laminates ◽  
Mechanical Performance ◽  
Polymeric Films ◽  
Epoxy Composites ◽  
Low Velocity Impact ◽  
Low Velocity ◽  
Lap Shear ◽  
Short Beam ◽  
Monitoring Applications ◽  
Beam Shear

This paper presents experimental results on the mechanical performance of advanced carbon/epoxy composites with embedded polymeric films. The composite laminates with polymeric films, which are potentially used as a sensor/actuator carrier for structural health monitoring applications, were investigated under various mechanical loadings including low velocity impact, single lap shear and short beam shear. The preliminary work showed that embedment of those polymeric films does not degrade, but could significantly improve, the mechanical properties of the composite laminates.

Effect of Electrospun Fibers on the Interlaminar Properties of Woven Composites

2008 ◽  
Vol 47-50 ◽  
pp. 1031-1034 ◽  
Author(s):  
Ajit D. Kelkar ◽  
Ram Mohan ◽  
Ronnie Bolick ◽  
Sachin Shendokar
Keyword(s):  
Composite Laminates ◽  
Hybrid Composites ◽  
Electrospun Fiber ◽  
Low Velocity Impact ◽  
Woven Composites ◽  
Shear Tests ◽  
Fiber Glass ◽  
Electrospinning Technique ◽  
Short Beam ◽  
Beam Shear

Failure by delamination of composite laminates due to low velocity impact damages is critical because of the subsurface nature of delamination. Traditional methods such as stitching and Zpinning, while improving interlaminar properties in woven composites, lead to a reduction of the inplane properties. To alleviate these problems, use of Tetra Ethyl Orthosilicate (TEOS) nano fibers manufactured using electrospinning technique in fiber Glass-Epon composite laminates is investigated for their potential to improve the interlaminar properties. Electrospun coated fiber glass woven mats are impregnated with epoxy resin using Heated-Vaccum Assisted Resin Transfer Moulding (H-VARTM) process. The interlaminar properties of the nano engineered hybrid composites obtained using ASTM Double Cantilever Beam (DCB) tests and short beam shear tests are compared with those without the presence of electrospun fiber layers, to study their influence. The short beam shear tests revealed a 20% improvement due to presence of TEOS interlaminar electrospun nanofibers. It is also noteworthy that fibers cured at different temperature levels had variation in performance as observed in MSBS test results.

Sign in / Sign up

Export Citation Format

Share Document