Monomer Casting Nylon Research Articles

Carbon felt/nitrogen-doped graphene/paraffin wax 3D skeleton regulated tribological performances of the MCPA6 composites: A novel strategy of oil embedding and transporting

A novel carbon felt/nitrogen-doped reduced graphene oxide/paraffin wax ternary skeleton (CF/N−RGO/PW) is developed to enhance the tribological performances of monomer casting nylon-6 (MCPA6). FE−SEM results confirm the successful formation of the three-dimensional (3D) CF/N−RGO/PW skeleton, where N−RGO sheets are decorated on carbon fibers. Most importantly, the flexuous N−RGO sheets can accommodate PW to provide sufficient lubricity for MCPA6, working as ponds to store PW. On the other hand, abundant cracks are found along carbon fibers, working as ditches to transport PW onto the rubbing surface. Thus, the ternary CF/N−RGO/PW 3D skeleton exhibits a pond and ditch structure for the efficient storage and transportation of PW. In comparison with the neat MCPA6, the friction coefficient and wear loss of MCPA6/CF/N−RGO/PW decline by (83 and 65) %, respectively. Theoretical calculations based on density functional theory support the efficient adsorption of PW onto N−RGO. Therefore, the as-prepared MCPA6/CF/N−RGO/PW composite herein provides a new reference to prepare polymer composites with advanced tribological performance on account of the novel strategy of the storage and transportation of lubricants.

Superior mechanical and tribological properties of short-cut carbon fiber reinforced monomer casting nylon composites after heat treatment

The effect of oil and water treatment with respect to the mechanical and tribological properties of short-cut carbon fiber (SCF)/monomer casting (MC) nylon composites was investigated. It was found that both the oil and water treatment can improve the crystallinity of SCF/MC nylon composites. The tensile strength and impact strength of oil treatment composites increase and the friction coefficient and the volumetric wear decrease. In addition, the water treatment is not as effective as oil treatment in improving material properties. This work would provide significant guidance for the preparation and post-treatment of SCF/MC nylon composites with excellent properties. It is also a useful attempt to develop new composite materials further to meet the needs of certain special spiral drives.

Preparation and properties of carboxylated cellulose nanofibers/monomer casting nylon composites

AbstractPolyisocyanate was used to chemically functionalize carboxylated cellulose nanofibers (CNF‐C). Composites of CNF‐C/ monomer casting nylon (MC nylon) and modified CNF‐C/MC nylon were fabricated by anionic ring‐opening polymerization. The mechanical characteristics of the MC nylon composites and the dispersion of the CNF‐C in the MC nylon were studied. The tensile strength and impact strength of composites were first increased with CNF‐C addition, but then decreased as further CNF‐C was added. The composites had good mechanical properties when CNF‐C was added to MC nylon at 1.0 wt%, and the tensile strength and impact strength were increased by 21.2% and 34.9%, respectively, compared to MC nylon. When modified CNF‐C was added at 1.5 wt%, the tensile strength of composites was increased by 47.90%. The addition of CNF‐C causes an increase in the melting point, crystallinity, and crystallization temperature, which was confirmed by differential scanning calorimetry (DSC). The modified CNF‐C had better dispersibility in MC nylon which was confirmed by scanning electron microscopy (SEM).

Mechanical simulation study of reapproximated sternum rigidity comparing sternal fixation devices.

A reliable sternal fixation is one of the most basic parts of cardiac surgery requiring sternotomy for preventing wound complications and promoting early recovery. Although various products have been released to the markets, the characteristics of each device are still unclear. A simulation study was conducted to compare the properties of two sternal fixation device: a commonly used monofilament stainless-steel wire and a newly designed cable comprised of several titanium alloys strands. Sternum models made of monomer casting nylon were tied with each material and displaced in longitudinal, antero-posterior, and horizontal directions. Resistance against each directional external force was measured and compared. The titanium cable showed a higher resistance to every directional displacement since slight deviations and a twofold higher maximum strength than the stainless wire. An in vitro simulation study revealed the titanium cable system provide stronger sternum fixation than stainless-steel wire.

Preparation of an aminographene–aliphatic hydroxyl-terminated polysiloxane hybrid for synergistic enhancement of the mechanical and tribological performance of monomer casting nylon 6

UFG–AHPDMS hybrid with covalent linkage was prepared by reaction of GO/urea/AHPDMS. Addition of UFG–AHPDMS led to enhancement of mechanical/tribological property of MC PA6 with synergistic reinforcing/friction reduction effect.

Tribological performances and self-lubricating mechanism of monomer casting nylon-6 composite coatings containing lube base oil-loaded microcapsules

The tribological properties of monomer casting nylon-6 (MC PA6) play an important role in ensuring energy consumption, component integrity and reliability in construction machinery. In this work, MC PA6 coatings containing different amount of lube base oil-loaded poly(urea-formaldehyde) microcapsules are prepared, and the tribological properties of the composite coatings are investigated. Compared with the pure coating, the friction coefficient and specific wear rate of the composite coating containing 20 wt% of oil-loaded microcapsules are 0.16 and 0.47 × 10−5 mm3/Nm, which correspond to decreases of 56.7% and 91.8% respectively. Moreover, by introducing the oil-loaded microcapsules, the heat produced during friction is greatly reduced and the friction temperature of all composite coatings (~40–50 °C) decreases more than 40 °C, as compared with that of pure coating (93.7 °C). Self-lubricating mechanism is investigated through microscopy and EDS analysis, which indicate that the improvement of tribological properties is attributed to the formation of uniform, continuous and thin lubricating film on the worn surface. This study would provide significant guidance for the design and preparation of MC PA6 composite coatings with high self-lubricating properties.

In situ reinforcing of monomer casting nylon-6 with nylon fiber and the interface failure mechanism

ABSTRACT Nylon fiber with identical structure with PA6 was firstly applied as reinforcing filler, and MC PA6/nylon fiber composites were in situ synthesized by introducing polyethylene glycol (PEG). Thus interfacial interaction, uniformity, and dispersion of composite were improved without settling of fibers in caprolactam during polymerization. Effect of nylon fiber content on polymerization kinetics was studied, and crystallization behavior and mechanical properties of composites were investigated, while nylon fiber-PEG showed reinforcing and toughening effect on matrix. Under stress, nylon fiber with skin-core structure was pulled out without interfacial debonding, resulting in ductile fracture with large deformation on fractured surface of composite.

Preparation and properties of wear‐resistant and flame‐retardant polyphenylsulfoneurea/monomer casting nylon copolymers

AbstractA poly(phenylsulfone)‐urea (PPSUU) macro‐activator is synthesized by in situ anionic polymerization of 4,4′‐diaminodiphenylsulfone and hexamethylene diisocyanate. The PPSUU segment is embedded into the nylon molecular chain through copolymerization to improve the wear resistance and flame retardancy of monomer cast nylon 6 (MC PA6) materials. The mechanical properties, thermal stability, friction and wear properties and combustion heat release rate of copolymers with different macro‐activator contents are tested. Results indicate that a small amount of PPSUU can improve the wear resistance and impact properties of nylon materials. The wear loss of MC nylon is 54.8% less than pure MC nylon from 1.049 × 10−8 to 0.474 × 10−8 g/Nm with 6 wt% PPSUU. Moreover, better flame retardancy is verified. The peak of HRR reduced 36.8% from 654 to 413 kw/m2 with 4 wt% PPSUU, accompanied by advanced ignition time and flame extinction time, thus reducing the risk of fire.

Modified α-Al2O3/oil-impregnated monomer casting nylon nanocomposite with both improved friction and mechanical properties

ABSTRACT For shock-absorbing and wear-resistant devices, there is an urgent need for monomer casting nylon (MC nylon) with excellent friction properties and mechanical properties simultaneously. Liquid lubricating oil is known to reduce friction effectively, but it will cause a dramatical decline in the mechanical properties of oil-impregnated monomer casting nylon (OMC nylon). Herein, α-Al2O3 nanoparticles modified by γ-aminopropyl triethoxy silane (APTS) were filled into OMC nylon, and the tribological and mechanical properties of APTS-α-Al2O3/OMC nylon composite were investigated systematically. Compared with OMC nylon, the addition of 0.1 wt% APTS-α-Al2O3 resulted in 19.5% increase in the tensile strength, 33.4% and 29.1% growth in compressive strength and modulus, 30.8% and 33.1% growth in flexural strength and modulus, respectively. Meanwhile, over 44% and 64.8% reduction in the friction coefficient and abrasion quality, respectively, were achieved for the nanocomposite. And the worn surface displayed smooth features, confirming the abrasion resistance of APTS-α-Al2O3. Hence, the combination of lubricating oil and α-Al2O3 is an appropriate choice when excellent mechanical and tribological properties are required to broaden the application field of MC nylon much further.

Synergistic effects of graphene oxide and paraffin wax on the tribological properties of monomer casting nylon-6 composites

In this work, monomer casting nylon-6 (MCPA6)/melamine foam (Me)/graphene oxide (GO)/paraffin wax (PW) composites were synthesized using Me foam as a three-dimensional template and adsorbing GO and PW on the Me foam skeleton. The microstructure and tribological behaviors of the MCPA6/Me/GO/PW composites were determined and the interaction of PW with GO were theoretical investigated. The results showed that the addition of both GO and PW significantly improved the tribological properties of the composites. Compared with pure MCPA6, the friction coefficient and specific wear rate of the composite with the ratio of 2:3.5 (GO to PW) were reduced by 82% and 84%, respectively. The improvement of tribological performance was attributed to the synergistic lubrication and anti-wear effects of PW and GO.

Influence of welding parameters on morphology and mechanical performance of friction spot pressure welded thin monomer cast nylon 6 sheets

In this paper, 1-mm-thickness monomer cast nylon 6 sheets were joined under the pressure and the frictional heat generated between the pinless tool and thin stainless steel plates, which was named friction spot pressure welding technology. Influences of welding parameters on spot weld diameter, morphology, and mechanical performance were investigated. Results showed that incomplete interfacial bonding was observed under insufficient plunge depth. Increased rotational speed, plunge depth, and dwell time caused severer extrusion ring and reticular cracks on the joint surface. Material overheating occurred under rotational speed of 1000 rpm and material adhesion on the back of steel plate happened under plunge depth of 0.25 mm. The weld-bonded area diameter increased with larger welding parameters, but the corresponding joint fracture loads increased and then decreased. Four failure modes including lap interface tearing (IT), upper sheet fracture (UF), outer bonding area separation (BS), and the mixed UF and BS were observed. Spot welds failed with UF possessed the maximum tensile load while joints fractured with IT showed low performance. Three different morphologies were observed on the fracture surface of the IT joints while the fracture surfaces of the joints failed with other fracture modes showed elongated strips and flocculent structures.

Effect of modified Mg2B2O5w on mechanical and friction properties of oil‐containing monomer casting nylon

ABSTRACTThe Mg2B2O5w modified by toluene‐2, 4‐diisocyanate (TDI) and fatty amine (n‐dodecylamine(D) or n‐octadecylamine (O)) was used in oil‐containing monomer casting (OMC) nylon, and the effect of modified Mg2B2O5w on mechanical and friction properties of OMC nylon composites was investigated. The significant improvement of the mechanical and friction properties of composites was observed. The addition of 0.15 wt% TDI‐D‐Mg2B2O5w or TDI‐O‐Mg2B2O5w resulted in 21 and 20% growth in the tensile strength, 53 and 52% increase in the flexural strength, respectively. Additionally, nearly 60 and 58% reduction in the friction coefficient, about 84 and 80% decrease in the abrasion quantity. Furthermore, the worn surface of composites exhibited smooth, which confirmed the antiwear effect of Mg2B2O5w. The improvement was attributed to the interfacial adhesion between whiskers and matrix by hydrogen bonds. This work provided a facile approach to the design of wear‐resistant polymer composites that hold significant potential in construction machinery industry. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020, 137, 48856.

Polydimethylsiloxane/monomer casting nylon copolymers: Preparation, flame‐retardant properties, and wear‐resistant properties

ABSTRACTIn order to improve the toughness, wear resistance, and combustion properties of the monomer casting nylon (MC nylon) materials, the polydimethylsiloxane (PDMS) segment is bonded to the nylon molecular chain by copolymerization. PDMS/MC nylon copolymers are prepared via in situ anionic polymerization with macro‐activator based on PDMS terminated with hexamethylene diisocyanate. The effects of different macro‐activator content on the mechanical properties, water absorption, thermal stability, friction and wear properties, and combustion properties of the copolymers are characterized. The results show that the impact strength of the copolymer improves significantly (optimally increases by 2.6 times) and the water absorption rate decreases with the increase of PDMS content. The introduction of the silicon–oxygen structure reduces the peak heat release rate of copolymer materials (optimally decreases about 28.7%), while it promotes the decomposition of the system, resulting in a slight decrease in the thermal stability of the materials. Adding 5 wt % PDMS can decrease the wear loss of MC nylon from 6.2 mg of pure nylon to 1.6 mg. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020, 137, 48753.

Simultaneous enhancements of mechanical and thermal properties of monomer cast nylon via polydimethylsiloxane‐modified kaolin

AbstractPolydimethylsiloxane (PDMS)‐modified Kaolin was prepared by the reaction between kaolin and PDMS. MC nylon 6/kaolin and MC nylon 6/kaolin‐PDMS composites with different filler contents were prepared through in situ polymerization. Thermogravimetric analysis and differential scanning calorimetry analysis show that the feeding of kaolin improved thermal stability and crystallinity of nylon. When 1 wt% addition of kaolin‐PDMS, the tensile strength and impact strength of the as‐prepared composites reached a maximum value of 77.7 MPa and 4.5 kJ/m2, respectively, exhibiting remarkable mechanical properties. Meanwhile, the water absorption capacity of the as‐prepared composites was greatly reduced by 60% with the addition of kaolin, and the modified kaolin possesses even better performances. The results show that the treated kaolin can greatly enhance the properties of cast nylon and has an outstanding application prospect.

Oil‐impregnated monomer casting nylon composites reinforced by graphene oxide and Lanthanum(III) chloride

Oil‐impregnated monomer casting (OMC) nylon composites reinforced by graphene oxide and Lanthanum(III) chloride (LaCl3) were prepared by anionic ring‐opening polymerization in the presence of sodium hydroxide catalyst and toluene‐2, 4‐diisocyanate cocatalyst. The cross‐linked GO was formed by the coordination and electrostatic interactions between La3+ and the carboxyl on the edge of GO, which resulted in an obvious reinforcement for the OMC nylon composites. The effects of different rare earth contents on mechanical and tribological properties of the composites were carried out. The results showed that the composites exhibited excellent comprehensive properties when 0.01 wt% GO and 0.007 wt% LaCl3 were incorporated in OMC nylon. The elastic modulus, flexural strength, flexural modulus, compressive strength, notched impact strength, and elongation‐at‐break for the OMC nylon/GO/LaCl3 composites increased by 6.1, 9.9, 18.2, 7.2, 40.8, and 24.4%, respectively, and the tensile strength was slightly improved. In addition, the abrasion quantity was reduced. POLYM. ENG. SCI., 59:982–988, 2019. © 2019 Society of Plastics Engineers

Chemically functionalized SiO2 to improve mechanical properties of oil‐impregnated monomer casting nylon

ABSTRACT: Toluene‐2,4‐diisocyanate and dodecanol were used to chemically functionalize nanosilica (TDID‐SiO2). Composites of TDID‐SiO2 and oil‐impregnated monomer casting nylon (OMC nylon) were prepared by an in situ anionic ring‐opening polymerization. The dispersion of the TDID‐SiO2 in oil was studied along with the mechanical and friction properties of the composites. The results show that the dispersion of the TDID‐SiO2 in oil was significantly enhanced. Specifically, some TDID‐SiO2 was wrapped in oil droplets, and the size of the oil droplets increased from 2.3 to 3.3 μm for 0–0.125 wt % of the TDID‐SiO2 nanoparticles, which was confirmed by scanning electron microscopy. The composites exhibited excellent mechanical properties when 0.10 wt % TDID‐SiO2 was integrated into OMC nylon. The tensile strength, elastic modulus, notched impact strength, flexural strength, and flexural modulus increased by 6.9%, 7.1%, 33.2%, 15%, and 77.5%, respectively, compared to OMC nylon without TDID‐SiO2 nanoparticles. The friction coefficient was effectively controlled and the abrasion quantity was reduced. Thermogravimetric analysis showed that the thermal decomposition temperature was also improved. The improved mechanical and frictional properties of TDID‐SiO2/OMC nylon composite will enhance its application in wear‐resistant products in heavy industry. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 46994.

Simultaneous enhancements of mechanical and thermal properties of monomer cast nylon via kaolin modified by poly (ethylene glycol diglycidyl ether)

ABSTRACTMonomer cast nylon was incorporated with different contents of kaolin, which is grafted with poly (ethylene glycol diglycidyl ether) via in-situ polymerization. The influence of treated-kaolin and kaolin contents on composites properties was studied. Treated-kaolin has a better effect on the properties of nylon than kaolin. Thermogravimetric analysis and Differential scanning calorimetry analysis show that that the feeding of kaolin improved thermal stability and crystallinity of nylon. The results indicate that using treated-kaolin as reinforcement, the composites displayed remarkable mechanical properties, the tensile strength and notched impact strength are 83.6 MPa and 4.46 MPa, respectively. The water absorption capacity of composites was greatly reduced by 50% with the feeding of kaolin.

Study on the Tribological Properties of MC Nylon Composites Filled with Hydraulic Oil

Mechanical parts utilized in machinery, such as nylon slider and pulley, should have certain mechanical properties and good tribological properties, so that equipments’ stability and smoothness can be assured. A kind of MC nylon (monomer cast nylon) composites filled with hydraulic oil was studied in this paper. The addition of hydraulic oil changed nylon’s mechanical properties and tribological properties significantly, and improved the material’s toughness and coefficient of friction. The composites have excellent strength, toughness and relatively low coefficient of friction when the content of the hydraulic oil is 4wt%.

In Situ Synthesis of Monomer Casting Nylon-6/Graphene-Polysiloxane Nanocomposites: Intercalation Structure, Synergistic Reinforcing, and Friction-Reducing Effect.

On the basis of the industrialized graphene nanosheets (GNs) product, we synthesized monomer casting nylon-6 (MC PA6)/GN-3-aminopropyl-terminated poly(dimethylsiloxane) (APDMS) nanocomposite in situ through the anchoring effect of APDMS onto the GN surface. APDMS/PA6 molecules were confirmed to intercalate into the GN layers by the formation of strong interfacial interactions. The intercalation ratio and the average layer thickness of the grafted GN sample decreased in the presence of APDMS. Moreover, for MC PA6/GN-APDMS nanocomposite, GN-APDMS was uniformly distributed in the matrix and no phase separation was observed. The size of spherical APDMS particles was obviously reduced compared with that of MC PA6/APDMS composite, revealing a strong interaction between APDMS and GN and the enhancement of compatibility in the composite system. Compared with neat MC PA6, the addition of GN-APDMS resulted in 12% increase in the tensile strength and 37% increase in the impact strength; meanwhile, increase in both the storage modulus (E') and the glass transition temperature (Tg) indicated synergistic reinforcing and toughening effect of GN-APDMS on MC PA6. Furthermore, over 81 and 48% reduction in the friction coefficient and the specific wear rate, respectively, was achieved for the nanocomposite, and the worn surface displayed flat and smooth features with a uniform depth distribution, a low annealing effect, and a reduced friction heat, further confirming the synergistic friction-reducing effect of GN-APDMS on MC PA6.

Structure and Tribological Performance of Monomer Casting Nylon-6/Colloidal Graphite Composites Synthesized through in Situ Polymerization

ABSTRACTA series of monomer casting nylon-6/colloidal graphite composites were synthesized through in situ anionic ring-opening polymerization. It was found that colloidal graphite layers modified with titanate coupling agent had a uniform distribution in the matrix, and the molecular weight of monomer casting nylon-6 decreased slightly below 5 wt% titanate coupling agent-colloidal graphite content. The crystallizing ability was much improved at lower titanate coupling agent-colloidal graphite content, indicating the nucleation effect of titanate coupling agent-colloidal graphite on monomer casting nylon-6. The notched charpy impact strength of the composites increased by addition of 0.5–1 wt% titanate coupling agent-colloidal graphite, and the obvious ductile fracture characteristics was presented. Meanwhile the storage modulus and the glass transition temperature (Tg) increased, and the loss factor (tan δ) decreased by addition of titanate coupling agent-colloidal graphite, indicating the toughening effect of titanate coupling agent-colloidal graphite on monomer casting nylon-6 matrix and improvement of the stiffness of the composites. Compared with neat monomer casting nylon-6 specimen, the composites presented a remarkable lower friction coefficient at the initial friction stage, and the wear resistance of monomer casting nylon-6/4 wt% titanate coupling agent-colloidal graphite specimen was enhanced by more than 10-fold. For neat monomer casting nylon-6, the melting and crystallization temperature, and crystallinity of the worn surface were obviously higher than that of the bulk part, indicating that the surface was fully annealed and the crystallizing ability was improved under produced friction heat, resulting in a poor anti-wear performance with abrasive wear form. For monomer casting nylon-6/titanate coupling agent-colloidal graphite composite, the annealing degree of the surfaces exhibited much lower than that of neat monomer casting nylon-6, due to the protective effect and suppression effect of titanate coupling agent-colloidal graphite layers and reduction of friction heat, resulting in the formation of uniform transfer film and a significant improvement of the wear resistance of the composites with the adhesive wear form.