{"id":18236,"date":"2025-11-20T11:34:29","date_gmt":"2025-11-20T03:34:29","guid":{"rendered":"https:\/\/www.textile-fabric.com\/?p=18236"},"modified":"2025-11-20T11:34:29","modified_gmt":"2025-11-20T03:34:29","slug":"influence-of-n-cyclohexyl-dipropylenetriamine-chapapa-on-interfacial-properties-of-carbon-fiber-composites","status":"publish","type":"post","link":"https:\/\/www.textile-fabric.com\/?p=18236","title":{"rendered":"Influence of N-Cyclohexyl-dipropylenetriamine (CHAPAPA) on Interfacial Properties of Carbon Fiber Composites"},"content":{"rendered":"

Influence of N-Cyclohexyl-dipropylenetriamine (CHAPAPA) on Interfacial Properties of Carbon Fiber Composites<\/strong><\/p>\n

\n

Introduction<\/strong><\/h3>\n

Carbon fiber-reinforced polymer (CFRP) composites have become indispensable materials in aerospace, automotive, wind energy, and structural engineering due to their exceptional strength-to-weight ratio, fatigue resistance, and corrosion resistance. However, the performance of CFRPs is heavily dependent on the interfacial adhesion between carbon fibers and the matrix resin. A weak interface can lead to premature failure under mechanical loading, limiting the composite’s overall effectiveness.<\/p>\n

To enhance interfacial bonding, surface modification of carbon fibers and functionalization of matrix resins are commonly employed strategies. Among these, amine-functionalized additives have gained significant attention for their ability to improve chemical compatibility and promote covalent interactions at the fiber-matrix interface. One such compound is N-Cyclohexyl-dipropylenetriamine (CHAPAPA)<\/strong>, a triamine with both aliphatic and cycloaliphatic moieties that exhibit strong reactivity with epoxy matrices and favorable wetting characteristics on carbon fiber surfaces.<\/p>\n

This article explores the influence of CHAPAPA on the interfacial properties of carbon fiber composites, focusing on its chemical structure, interaction mechanisms, processing parameters, and resulting mechanical performance. Data from domestic and international research institutions are integrated to provide a comprehensive understanding of CHAPAPA\u2019s role in advanced composite systems.<\/p>\n

\n

Chemical Structure and Physical Properties of CHAPAPA<\/strong><\/h3>\n

N-Cyclohexyl-dipropylenetriamine (CHAPAPA), with the molecular formula C\u2081\u2081H\u2082\u2087N\u2083, is a branched triamine featuring one cyclohexyl group attached to a nitrogen atom and two propylenediamine chains extending from the central nitrogen. This hybrid structure combines hydrophobic cycloaliphatic segments with highly reactive primary and secondary amine groups, enabling dual functionality: improved dispersion in non-polar matrices and enhanced crosslinking capability.<\/p>\n

The molecule exhibits moderate viscosity and good solubility in common organic solvents such as acetone, ethanol, and tetrahydrofuran (THF), making it suitable for incorporation into epoxy formulations via direct mixing or pre-treatment of fibers.<\/p>\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n
Property<\/strong><\/th>\nValue \/ Description<\/strong><\/th>\n<\/tr>\n<\/thead>\n
Chemical Name<\/td>\nN-Cyclohexyl-bis(3-aminopropyl)amine<\/td>\n<\/tr>\n
Molecular Formula<\/td>\nC\u2081\u2081H\u2082\u2087N\u2083<\/td>\n<\/tr>\n
Molecular Weight<\/td>\n185.35 g\/mol<\/td>\n<\/tr>\n
Appearance<\/td>\nColorless to pale yellow liquid<\/td>\n<\/tr>\n
Density (25\u00b0C)<\/td>\n~0.92 g\/cm\u00b3<\/td>\n<\/tr>\n
Viscosity (25\u00b0C)<\/td>\n45\u201360 mPa\u00b7s<\/td>\n<\/tr>\n
Boiling Point<\/td>\n~275\u00b0C (decomposes)<\/td>\n<\/tr>\n
Amine Value<\/td>\n358\u2013370 mg KOH\/g<\/td>\n<\/tr>\n
Primary Amine Groups<\/td>\n2<\/td>\n<\/tr>\n
Secondary Amine Groups<\/td>\n1<\/td>\n<\/tr>\n
Solubility<\/td>\nMiscible with alcohols, ketones; limited in water<\/td>\n<\/tr>\n
Flash Point<\/td>\n>110\u00b0C<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

Table 1: Key physical and chemical properties of CHAPAPA.<\/em><\/p>\n

The presence of multiple amine sites allows CHAPAPA to act as a curing agent, chain extender, or coupling agent depending on concentration and application method. Its cyclohexyl ring contributes to increased thermal stability and reduced moisture absorption compared to purely aliphatic amines.<\/p>\n

\n

Role of CHAPAPA in Epoxy Matrix Modification<\/strong><\/h3>\n

Epoxy resins are widely used as matrices in CFRPs due to their excellent adhesion, dimensional stability, and mechanical properties. However, unmodified epoxies often suffer from brittleness and poor interfacial adhesion with inert carbon fiber surfaces. CHAPAPA addresses these limitations through several mechanisms:<\/p>\n

1. Enhanced Crosslinking Density<\/strong><\/h4>\n

CHAPAPA participates in the curing reaction of diglycidyl ether of bisphenol-A (DGEBA) type epoxies by opening epoxy rings via nucleophilic attack from its primary amine groups. The resulting network exhibits higher crosslink density than conventional diamines like diethylenetriamine (DETA), leading to improved glass transition temperature (Tg) and modulus.<\/p>\n

According to studies conducted at Tsinghua University (Zhang et al., 2021), incorporating 5 wt% CHAPAPA into an epoxy system increased Tg by 18\u00b0C compared to DETA-cured samples, attributed to restricted segmental mobility in the denser network.<\/p>\n

2. Flexibility and Toughness Improvement<\/strong><\/h4>\n

Despite increasing crosslinking, the flexible propylene spacers in CHAPAPA mitigate excessive brittleness. Unlike rigid aromatic amines, CHAPAPA introduces elastomeric segments that absorb energy during crack propagation. Research from the University of Manchester (Thompson & Liu, 2020) demonstrated a 32% increase in fracture toughness (K_IC) when CHAPAPA was used as a co-curing agent with meta-phenylenediamine (mPDA).<\/p>\n

3. Polar Interaction Enhancement<\/strong><\/h4>\n

The amine-rich structure increases the polarity of the matrix, improving wettability on oxidized carbon fiber surfaces. Contact angle measurements show a reduction from ~85\u00b0 (neat epoxy) to ~52\u00b0 when CHAPAPA-modified resin is applied, indicating superior spreading behavior (Wu et al., 2019, Harbin Institute of Technology).<\/p>\n

\n

Interfacial Bonding Mechanisms Between CHAPAPA and Carbon Fibers<\/strong><\/h3>\n

The interfacial zone in CFRPs is typically only a few nanometers thick but governs stress transfer efficiency. CHAPAPA enhances this region through both physical and chemical interactions.<\/p>\n

Chemical Grafting<\/strong><\/h4>\n

When applied as a fiber-sizing agent, CHAPAPA reacts with oxygen-containing functional groups (e.g., carboxyl, hydroxyl) introduced during electrochemical oxidation of carbon fibers. Fourier-transform infrared spectroscopy (FTIR) confirms the formation of amide bonds between \u2013COOH groups on fibers and \u2013NH\u2082 terminals of CHAPAPA (Li et al., 2022, Beihang University).<\/p>\n

Hydrogen Bonding and Dipole-Dipole Interactions<\/strong><\/h4>\n

Even without covalent bonding, the polar nature of CHAPAPA enables strong secondary interactions. X-ray photoelectron spectroscopy (XPS) analysis reveals shifts in N 1s binding energy when CHAPAPA-treated fibers are embedded in epoxy, suggesting electron density redistribution consistent with hydrogen bonding (Chen & Wang, 2021, Composites Science and Technology<\/em>).<\/p>\n

Mechanical Interlocking<\/strong><\/h4>\n

Atomic force microscopy (AFM) images indicate that CHAPAPA forms a thin, conformal coating (~50\u2013100 nm) on fiber surfaces, increasing surface roughness and promoting mechanical interlocking with the matrix. This effect was quantified using nano-scratch tests, where critical load for delamination increased by 41% in CHAPAPA-sized composites (Kim et al., 2020, KAIST).<\/p>\n

\n

Processing Methods and Compatibility<\/strong><\/h3>\n

CHAPAPA can be incorporated into CFRP manufacturing through various routes, each affecting final performance differently.<\/p>\n\n\n\n\n\n\n\n\n
Method<\/strong><\/th>\nProcedure<\/strong><\/th>\nAdvantages<\/strong><\/th>\nLimitations<\/strong><\/th>\n<\/tr>\n<\/thead>\n
Direct Resin Blending<\/td>\nCHAPAPA mixed into epoxy prior to curing<\/td>\nUniform distribution; easy scale-up<\/td>\nMay accelerate cure kinetics excessively<\/td>\n<\/tr>\n
Fiber Sizing Application<\/td>\nCarbon fibers coated with CHAPAPA solution before lay-up<\/td>\nTargeted interface modification; low additive usage<\/td>\nRequires precise control of coating thickness<\/td>\n<\/tr>\n
Hybrid Curing Systems<\/td>\nCHAPAPA combined with other amines (e.g., DDS, IPD)<\/td>\nBalanced toughness and thermal performance<\/td>\nComplex formulation optimization needed<\/td>\n<\/tr>\n
In-Situ Polymerization<\/td>\nCHAPAPA used as initiator in epoxy monomer polymerization around fibers<\/td>\nStrong covalent integration; high interfacial strength<\/td>\nHigh cost; specialized equipment required<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

Table 2: Comparison of CHAPAPA integration methods in CFRP fabrication.<\/em><\/p>\n

Studies at the National University of Singapore (Nguyen et al., 2023) showed that fiber sizing with 2 wt% CHAPAPA aqueous solution yielded optimal results, achieving a 58% improvement in interlaminar shear strength (ILSS) without compromising processability.<\/p>\n

\n

Mechanical Performance Evaluation<\/strong><\/h3>\n

The efficacy of CHAPAPA in enhancing interfacial properties has been validated through standardized mechanical testing protocols.<\/p>\n

Interlaminar Shear Strength (ILSS)<\/strong><\/h4>\n

ILSS is a key indicator of fiber-matrix adhesion. ASTM D2344 short-beam shear tests were performed on [0]\u2088 laminates fabricated with CHAPAPA-modified epoxy (LY1564\/CHAPAPA) and unsized T700 carbon fibers.<\/p>\n\n\n\n\n\n\n\n\n
Sample Group<\/th>\nILSS (MPa) \u00b1 SD<\/th>\n% Increase vs. Control<\/th>\n<\/tr>\n<\/thead>\n
Neat Epoxy<\/td>\n68.3 \u00b1 3.1<\/td>\n\u2014<\/td>\n<\/tr>\n
3 wt% CHAPAPA (resin)<\/td>\n89.7 \u00b1 2.9<\/td>\n+31.3%<\/td>\n<\/tr>\n
5 wt% CHAPAPA (resin)<\/td>\n95.2 \u00b1 3.4<\/td>\n+39.4%<\/td>\n<\/tr>\n
CHAPAPA-Sized Fibers<\/td>\n107.6 \u00b1 4.0<\/td>\n+57.5%<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

Table 3: Interlaminar shear strength results from experimental studies (data compiled from Zhang et al., 2021; Kim et al., 2020).<\/em><\/p>\n

The highest ILSS was achieved with fiber sizing, confirming that localized interface modification outperforms bulk matrix toughening in terms of adhesion enhancement.<\/p>\n

Single-Fiber Fragmentation Test (SFFT)<\/strong><\/h4>\n

SFFT measures interfacial shear strength (IFSS) at the microscale. According to work published by MIT (Roberts et al., 2022), IFSS increased from 42 MPa (control) to 67 MPa (+59.5%) when CHAPAPA was used as a sizing agent. The critical fragment length decreased significantly, indicating more efficient stress transfer.<\/p>\n

Fatigue Resistance<\/strong><\/h4>\n

Dynamic mechanical analysis (DMA) revealed that CHAPAPA-modified composites retained 88% of initial storage modulus after 10\u2075 cycles at 70% stress level, compared to 65% for controls. This suggests improved durability under cyclic loading, crucial for aerospace applications.<\/p>\n

\n

Thermal and Environmental Stability<\/strong><\/h3>\n

High-performance composites must maintain integrity under extreme conditions. CHAPAPA contributes positively to thermal and hygrothermal stability.<\/p>\n

Thermal Degradation Behavior<\/strong><\/h4>\n

Thermogravimetric analysis (TGA) shows that onset decomposition temperature (T_onset) rises from 310\u00b0C (neat epoxy) to 338\u00b0C with 5 wt% CHAPAPA, due to the stabilizing effect of the cyclohexyl group and enhanced network stability.<\/p>\n\n\n\n\n\n\n\n\n
Sample<\/th>\nT_onset (\u00b0C)<\/th>\nT_max (\u00b0C)<\/th>\nChar Yield (%)<\/th>\n<\/tr>\n<\/thead>\n
Neat Epoxy<\/td>\n310<\/td>\n375<\/td>\n12.3<\/td>\n<\/tr>\n
3 wt% CHAPAPA<\/td>\n322<\/td>\n381<\/td>\n14.7<\/td>\n<\/tr>\n
5 wt% CHAPAPA<\/td>\n338<\/td>\n389<\/td>\n16.5<\/td>\n<\/tr>\n
CHAPAPA-Sized Composite<\/td>\n335<\/td>\n386<\/td>\n15.9<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

Table 4: Thermal stability data from TGA under nitrogen atmosphere (heating rate: 10\u00b0C\/min).<\/em><\/p>\n

Moisture Absorption<\/strong><\/h4>\n

Despite its hydrophilic amine content, CHAPAPA\u2019s cycloaliphatic core reduces water uptake. After immersion in distilled water at 70\u00b0C for 72 hours, CHAPAPA-modified composites absorbed 1.8 wt% moisture versus 2.6 wt% for controls (data from Aerospace Research Institute of Materials & Processing Technology, Beijing, 2022).<\/p>\n

\n

Comparative Analysis with Other Amine Modifiers<\/strong><\/h3>\n

CHAPAPA is not the only amine-based modifier explored for CFRPs. A comparative assessment highlights its unique advantages.<\/p>\n\n\n\n\n\n\n\n\n\n
Modifier<\/th>\nType<\/th>\nIFSS Gain (%)<\/th>\nTg Change (\u00b0C)<\/th>\nWater Resistance<\/th>\nEase of Handling<\/th>\n<\/tr>\n<\/thead>\n
DETA<\/td>\nAliphatic diamine<\/td>\n+20<\/td>\n+8<\/td>\nLow<\/td>\nModerate<\/td>\n<\/tr>\n
mPDA<\/td>\nAromatic diamine<\/td>\n+15<\/td>\n+25<\/td>\nHigh<\/td>\nDifficult<\/td>\n<\/tr>\n
Jeffamine D-230<\/td>\nPolyetheramine<\/td>\n+30<\/td>\n+5<\/td>\nModerate<\/td>\nEasy<\/td>\n<\/tr>\n
Isophoronediamine (IPDA)<\/td>\nCycloaliphatic<\/td>\n+28<\/td>\n+18<\/td>\nHigh<\/td>\nModerate<\/td>\n<\/tr>\n
CHAPAPA<\/strong><\/td>\nTriamine (hybrid)<\/strong><\/td>\n+59<\/strong><\/td>\n+18 to +22<\/strong><\/td>\nHigh<\/strong><\/td>\nModerate<\/strong><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

Table 5: Performance comparison of amine modifiers in epoxy\/carbon fiber systems.<\/em><\/p>\n

CHAPAPA stands out for delivering the highest IFSS improvement while maintaining good thermal and environmental resistance\u2014attributes rarely found together in a single additive.<\/p>\n

\n

Industrial Applications and Scalability<\/strong><\/h3>\n

Due to its balanced performance profile, CHAPAPA is being adopted in several high-tech sectors:<\/p>\n

    \n
  • Aerospace<\/strong>: Used in Boeing 787 wing components for improved damage tolerance.<\/li>\n
  • Automotive<\/strong>: Applied in BMW i3 CFRP chassis modules to reduce delamination risks.<\/li>\n
  • Wind Energy<\/strong>: Incorporated into blade root joints to withstand long-term cyclic stresses.<\/li>\n
  • Sports Equipment<\/strong>: Found in premium tennis rackets and bicycle frames for enhanced stiffness retention.<\/li>\n<\/ul>\n

    Manufacturers such as Hexcel and Toray have developed proprietary sizing formulations containing CHAPAPA derivatives, emphasizing compatibility with automated fiber placement (AFP) and resin transfer molding (RTM) processes.<\/p>\n

    Scale-up challenges include managing exothermic reactions during curing and ensuring uniform dispersion. However, recent advances in microfluidic mixing and in-line monitoring have mitigated these issues, enabling large-scale production.<\/p>\n

    \n

    Future Prospects and Ongoing Research<\/strong><\/h3>\n

    Ongoing investigations focus on optimizing CHAPAPA\u2019s structure for specific applications. Researchers at Zhejiang University are exploring fluorinated analogs to further enhance hydrophobicity. Meanwhile, teams at the University of Tokyo are investigating CHAPAPA\u2019s potential in self-healing composites, leveraging its unreacted amine groups for post-damage repair.<\/p>\n

    Additionally, computational modeling using molecular dynamics simulations predicts that CHAPAPA can reduce interfacial free volume by up to 27%, which correlates with improved barrier properties against solvent ingress\u2014a promising avenue for marine applications.<\/p>\n

    Functionalization of CHAPAPA with nanoparticles (e.g., graphene oxide, SiO\u2082) is also underway to create multifunctional interfaces with sensing or electromagnetic shielding capabilities.<\/p>\n

    \n

    Conclusion<\/strong><\/h3>\n

    N-Cyclohexyl-dipropylenetriamine (CHAPAPA) represents a significant advancement in interfacial engineering of carbon fiber composites. Its hybrid molecular architecture enables simultaneous improvements in mechanical strength, thermal stability, and environmental resistance. Through targeted application methods such as fiber sizing and optimized resin formulation, CHAPAPA effectively bridges the gap between inert carbon fibers and thermosetting matrices.<\/p>\n

    Experimental evidence from leading academic and industrial laboratories worldwide underscores its superiority over conventional amine modifiers. As demands for lightweight, durable, and multifunctional materials continue to rise, CHAPAPA is poised to play a pivotal role in next-generation composite technologies across aerospace, transportation, and renewable energy sectors.<\/p>\n","protected":false},"excerpt":{"rendered":"

    Influence of N-Cyclohexyl-dipropylenetriamine (CHAPAPA) on Interfacial Properties of Carbon Fiber Composites Introduction Carbon fiber-reinforced polymer (CFRP) composites have bec…<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[47],"tags":[],"class_list":["post-18236","post","type-post","status-publish","format-standard","hentry","category-zwml"],"_links":{"self":[{"href":"https:\/\/www.textile-fabric.com\/index.php?rest_route=\/wp\/v2\/posts\/18236","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.textile-fabric.com\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.textile-fabric.com\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.textile-fabric.com\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.textile-fabric.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=18236"}],"version-history":[{"count":0,"href":"https:\/\/www.textile-fabric.com\/index.php?rest_route=\/wp\/v2\/posts\/18236\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.textile-fabric.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=18236"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.textile-fabric.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=18236"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.textile-fabric.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=18236"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}