IM7/LARCTM-IA polyimide composites

1995 ◽  
Vol 7 (1) ◽  
pp. 105-124 ◽  
Author(s):  
T H Hou ◽  
N J Johnston ◽  
T L St Clair
Keyword(s):  
Mechanical Properties ◽  
Molecular Weight ◽  
High Performance ◽  
Flexural Modulus ◽  
Engineering Properties ◽  
Solvent Resistance ◽  
Polymer Backbone ◽  
Molecular Weights ◽  
Interlaminar Shear ◽  
Langley Research Center

LARCTM-IA (Langley Research Center-Improved Adhesive) aromatic polyimide, based on oxydiphthalic anhydride and 3.4'-oxydianiline, was evaluated as a matrix for high-performance composites. Six poly(amide acid)solutions in N-methylpyrrolidone (NMP), end-capped with phthalic anhydride to various theoretical molecular weights, were synthesized and their molecular weights and molecular weight distributions determined, Importantly, high concentrations of low-molecular-weight species were found in all the offset compositions. Except for the 1% offset polymer, all fully imidized films failed a solvent resistance test which involved immersion in acetone, methyl ethyl ketone, toluene, dimethylacetamide and chloroform for 1 min followed by a fingernail crease. Unidirectional prepreg was fabricated from each of the six resins by both standard drum winding procedures and the LARC multipurpose prepreg machine. The consolidation cycle developed previously for IM7/LARCTM-ITPI composites was found to be equally applicable for IM7/LARCTM-IA composites since both materials are similar and were prepared in and prepregged from NMP. An optimal end-capped resin composition was identified (4% stoichiometric imbalance) by using, as a screening tool, initial composite mechanical properties (short-beam shear strength, longitudinal flexural strength and flexural modulus) at room temperature, 93, 150 and 177°C. Composite engineering properties for the 4% offset composition were obtained, including longitudinal tension, transverse flexural, longitudinal compression, interlaminar shear, short block compression, open hole compression and compression strength after impact. Notably, the CAI strength was 303.2 MPa (44 Ksi) showing that the LARCTM-IA composites have good damage tolerance. A minor modification of LARCTM-IA polymer backbone which did not alter the consolidation cycle, designated as LARCTM-IAX, improved solvent resistance measurably. Mechanical properties of IM7/LARCTM-IAX composites were shown to be comparable to those exhibited by the baseline IM7/LARCTM-IA composites.

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.

scholarly journals Effect of Sizing Agents on Surface Properties of T800 Grade CF and Thermal Aging Time on Mechanical Properties of T800 Grade CF/Epoxy Composites

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Tian Yang ◽  
Yan Zhao ◽  
Hansong Liu ◽  
Shu Xiong
Keyword(s):  
Mechanical Properties ◽  
Molecular Weight ◽  
Aging Time ◽  
Surface Properties ◽  
Thermal Aging ◽  
Ageing Time ◽  
Flexural Modulus ◽  
Thermal Ageing ◽  
Epoxy Composites ◽  
Interlaminar Shear

This paper investigates the effect of sizing agent molecular weight on carbon fiber (CF) surface properties and the effect of thermal aging time on mechanical properties of CF/epoxy composites. The surface properties of three CCF800 CF samples with varying sizing agent molecular weight were characterized by surface morphology, surface roughness, chemical functional groups, and element composition. The results showed that the sample with low molecular weight exhibited low roughness and high proportion of activated carbon atoms. The flexural strength, flexural modulus, and interlaminar shear strength of CCF800/5228 composites were measured at 25°C and 150°C by thermal ageing time 0, 100 h, 250 h, 500 h, and 1000 h. The results showed that the thermal aging time up to 1000 h had little effect on the flexural modulus, and the interlaminar shear performance at 150°C showed a trend of increasing at the beginning and then decreasing.

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.

Synthesis of polyacrylonitrile and mechanical properties of its electrospun nanofibers

e-Polymers ◽  
2018 ◽  
Vol 18 (6) ◽  
pp. 569-573 ◽  
Author(s):  
Gaigai Duan ◽  
Shuwu Liu ◽  
Haoqing Hou
Keyword(s):  
Mechanical Properties ◽  
Molecular Weight ◽  
Carbon Nanofibers ◽  
High Performance ◽  
Mechanical Performance ◽  
Electrospun Nanofibers ◽  
Tensile Tests ◽  
Molecular Weights ◽  
Aligned Nanofibers ◽  
Absolute Viscosity

AbstractPolyacrylonitrile (PAN) nanofibers are very important to achieve high performance carbon nanofibers. In this work, co-polyacrylonitriles (co-PANs) with different molecular weights were synthesized by a simple free-radical polymerization. The effect of the initiator amount on the molecular weight of co-PAN was investigated. The co-PANs with different molecular weight were electrospun into aligned nanofibers by adjusting the absolute viscosity of co-PAN solution into ~1.0 Pa·s. All the co-PAN nanofibers showed smooth surfaces and homogeneous fiber diameters of ~450 nm. Tensile tests were applied to evaluate the mechanical properties of electrospun aligned co-PAN nanofibers. The results indicated that higher molecular weight led to better mechanical performance of electrospun aligned co-PAN nanofibers. When the molecular weight was 2.3×105, the highest strength of 153 MPa, strain of 0.148, and toughness of 16.0 J/g were obtained. These electrospun aligned co-PAN nanofibers could be good candidates for the preparation of high performance carbon nanofibers.

scholarly journals Effects of Molecular Weight of Functionalized Liquid Butadiene Rubber as a Processing Aid on the Properties of SSBR/Silica Compounds

Polymers ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 850
Author(s):  
Donghyuk Kim ◽  
Byungkyu Ahn ◽  
Kihyun Kim ◽  
JongYeop Lee ◽  
Il Jin Kim ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Anionic Polymerization ◽  
High Performance ◽  
Crosslink Density ◽  
Functional Group ◽  
Vital Role ◽  
Butadiene Rubber ◽  
Molecular Weights ◽  
Mooney Viscosity ◽  
Silica Dispersion

Liquid butadiene rubber (LqBR) which used as a processing aid play a vital role in the manufacturing of high-performance tire tread compounds. However, the studies on the effect of molecular weight, microstructure, and functionalization of LqBR on the properties of compounds are still insufficient. In this study, non-functionalized and center-functionalized liquid butadiene rubbers (N-LqBR and C-LqBR modified with ethoxysilyl group, respectively) were synthesized with low vinyl content and different molecular weights using anionic polymerization. In addition, LqBR was added to the silica-filled SSBR compounds as an alternative to treated distillate aromatic extract (TDAE) oil, and the effect of molecular weight and functionalization on the properties of the silica-filled SSBR compound was examined. C-LqBR showed a low Payne effect and Mooney viscosity because of improved silica dispersion due to the ethoxysilyl functional group. Furthermore, C-LqBR showed an increased crosslink density, improved mechanical properties, and reduced organic matter extraction compared to the N-LqBR compound. LqBR reduced the glass transition temperature (Tg) of the compound significantly, thereby improving snow traction and abrasion resistance compared to TDAE oil. Furthermore, the energy loss characteristics revealed that the hysteresis loss attributable to the free chain ends of LqBR was dominant.

Semi-bio-based aromatic polyamides from 2,5-furandicarboxylic acid: toward high-performance polymers from renewable resources

RSC Advances ◽  
2016 ◽  
Vol 6 (90) ◽  
pp. 87013-87020 ◽  
Author(s):  
Kaiju Luo ◽  
Yan Wang ◽  
Junrong Yu ◽  
Jing Zhu ◽  
Zuming Hu
Keyword(s):  
Mechanical Properties ◽  
Thermal Stability ◽  
Molecular Weight ◽  
High Molecular Weight ◽  
Renewable Resources ◽  
High Performance ◽  
Good Thermal Stability ◽  
Aromatic Polyamides ◽  
High Performance Polymers ◽  
Furandicarboxylic Acid

Aromatic furanic polyamides with relatively high molecular weight were synthesized, and good thermal stability and mechanical properties were demonstrated.

Synthesis of Cyclic Polysulfides and their Properties as Curing Agents

2004 ◽  
Vol 77 (2) ◽  
pp. 380-390
Author(s):  
Wonmun Choi ◽  
Tomoyuki Matsumura
Keyword(s):  
Mechanical Properties ◽  
Molecular Weight ◽  
Tensile Strength ◽  
High Molecular Weight ◽  
Mass Spectra ◽  
Elongation At Break ◽  
Molecular Weights ◽  
Aging Properties ◽  
Curing Agents ◽  
Polysulfide Polymer

Abstract The reactions of dichloroalkanes and sodium tetra-sulfide (Na2S4) were carried out in a mixture of water and toluene to produce corresponding cyclic polysulfides and polysulfide polymer. The low molecular weights of cyclic sulfides were obtained by the reaction at 90 °C, while the high molecular weight of polysulfide polymer was obtained by the reaction at 50 °C. GPC chromatograms and Mass spectra revealed that the structures of cyclic polysulfide were 1:1, 2:2, and 3:3 adducts of dichloroalkane and sodium tetra-sulfide. The mechanical properties of vulcanized NR at 148 °C with cyclic sulfides were similar to that with sulfur. However, both tensile strength and elongation at break of vulcanized NR at 170 °C with cyclic sulfides are much higher than that with sulfur. The aging properties of vulcanized NR at 148 °C or 170 °C with cyclic polysulfides indicate better stability.

Comparison of exopolysaccharides from mucoid and nonmucoid strains of Clavibacter michiganensis subspecies sepedonicus

1993 ◽  
Vol 39 (3) ◽  
pp. 291-296 ◽  
Author(s):  
Paul J. Henningson ◽  
Neil C. Gudmestad
Keyword(s):  
Molecular Weight ◽  
High Performance ◽  
Size Exclusion ◽  
Enzyme Linked Immunosorbent Assay ◽  
Low Molecular Weight ◽  
Neutral Sugar ◽  
Clavibacter Michiganensis ◽  
Serological Reaction ◽  
Molecular Weights ◽  
Exclusion Chromatography

The exopolysaccharides produced by six strains of Clavibacter michiganensis ssp. sepedonicus were isolated and purified by liquid chromatography. Neutral sugar composition and molecular weights were determined for each polysaccharide fraction, using gas chromatography and high-performance size-exclusion chromatography. The serological reaction of each fraction was tested using enzyme-linked immunosorbent assay. Exopolysaccharide from nonmucoid strains contained only low molecular weight polysaccharides (1.5 × 103 to 1.1 × 104). Exopolysaccharide from mucoid and intermediate strains could be separated into low (4.0 × 103 to 1.1 × 104) molecular weight and high (5.0 × 105 to 1.6 × 106) molecular weight fractions. High molecular weight polysaccharides were composed almost exclusively of galactose, glucose, and fucose. The ratios of these sugars were highly variable among strains. Low molecular weight polysaccharides were primarily composed of galactose with significant and varying amounts of glucose, rhamnose, mannose, and ribose. All polysaccharide fractions except one, produced by a nonmucoid strain, reacted in the immunoassay test.Key words: exopolysaccharide, polysaccharide, Clavibacter, michiganensis, sepedonicus.

Influence of Processing Aids and Hydroxyapatite as Fillers on Flow Behaviour and Mechanical Properties of Ultra High Molecular Weight Polyethylene/High Density Polyethylene Composites

2011 ◽  
Vol 471-472 ◽  
pp. 827-832 ◽  
Author(s):  
Mazatusziha Ahmad ◽  
Mat Uzir Wahit ◽  
Mohammed Rafiq Abdul Kadir ◽  
Khairul Zaman Mohd Dahlan
Keyword(s):  
Mechanical Properties ◽  
Molecular Weight ◽  
High Molecular Weight ◽  
High Density Polyethylene ◽  
Flexural Modulus ◽  
High Density ◽  
Compression Moulding ◽  
Biomedical Implant ◽  
Bone Properties ◽  
Ultra High Molecular Weight

In this study, blends of ultra high molecular weight polyethylene/high density polyethylene/polyethylene glycol (UHMWPE/HDPE/PEG) and the composites containing Hydroxyapatite (HA) as reinforcement filler were prepared via single screw extruder nanomixer followed by compression moulding. PEG (2phr) was used as processing aid and HA loadings were varied from 10 to 50 phr. HDPE and PEG were introduced to improve the extrudability of UHMWPE. Rheological behavior was studied via capillary rheometer while flexural and izod impact tests were conducted in order to investigate the mechanical properties of the blends and composites. Melt viscosity of the blends was found to decrease with increasing shear rate indicating a pseudoplastic behaviour. Incorporation of PEG shows a synergism effect on the reduction of blends viscosity. Blend of 40% UHMWPE/ 60% HDPE/ 2 phr PEG was chosen as the optimum blend composition with a balance properties in terms of the mechanical properties and processability. The incorporation of HA fillers from 10 to 50 phr into the blend resulted in the increase of flexural modulus and flexural strength with a slight decline of impact strength values. It can be concluded that the composites having adequate strength and modulus within the range of cancellous bone properties were succesfully developed to be used as biomedical implant devices.

Mechanical properties of wood flour/poly (lactic acid) composites coupled with waterborne silane-polyacrylate copolymer emulsion

Holzforschung ◽  
2016 ◽  
Vol 70 (5) ◽  
pp. 439-447 ◽  
Author(s):  
Ru Liu ◽  
Shupin Luo ◽  
Jinzhen Cao ◽  
Yu Chen
Keyword(s):  
Mechanical Properties ◽  
Lactic Acid ◽  
High Performance ◽  
Coupling Effect ◽  
Wood Flour ◽  
Flexural Modulus ◽  
Coupling Agents ◽  
Poly Lactic Acid ◽  
Effective Coupling ◽  
Methacryloxypropyl Trimethoxysilane

Abstract Wood flour/polylactic acid (WF/PLA) composites were produced with a WF content of 50% based on three types of waterborne polyacrylate (PA) emulsions including a PA homopolymer emulsion and two types of silane-PA copolymer emulsions as coupling agents. Two silanes were in focus, namely, γ-methacryloxypropyl- trimethoxysilane (silane-1) and vinyltrimethoxysilane (silane-2). The emulsions and the modified WFs were characterized, and the effects were investigated in terms of emulsion type and their loading levels on the mechanical properties of WF/PLA composites. (1) Both types of silanes could be successfully copolymerized with PA to form stable emulsions. (2) With increasing PA loading, the mechanical properties (except for flexural modulus) of the composites increased at first before reaching the maximum values at 4% PA loading and then the properties worsened. However, these values were larger than those of pure composites, especially in cases when PA-silane emulsions were applied. (3) PA modified with silane-1 showed the best coupling effect among all the three PA emulsions. The results can be interpreted that PA emulsions are effective coupling agents for the preparation of high-performance WPCs.

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