MC Nylon Research Articles

Research into High Performance Zeolite/Monomer Casting Nylon 6 (MCPA6) Composites

Zeolite / MC nylon 6 composites were prepared , followed by morphology and properties characterization of composites. The results demonstrated that a large number of pearlitic structures appeared at the interphase between the organic phases and the inorganic phases, indicating that caprolactam had happened anionic in-situ polymerization within the zeolite. The zeolite played a role of molecular rivet in zeolite / MCPA6 composites. The experimental results also showed that the composites performances were largely improved compared with pure MCPA6. When zeolite was 1 Phr, the impact strength of the composite was increased by 58%, temperature of thermal decomposition was rised by 92.9 °C. When zeolite reached 5 Phr, the composite shrinkage rate was reduced by 33%.

Characterization of Zeolite/Monomer Casting Polyamide 6 Composites

Monomer casting polyamide 6 (MCPA6) was modified by zeolite whose microstructure owns nanoscale holes which has excellent interfacial compatibility with MCPA6. The zeolite / MCPA6 composites were prepared by anionic in-situ polymerization. FTIR indicated that the addition of zeolite did not cause adverse reaction in the reaction system. The results also showed that zeolite / MCPA6 composites had two melting peaks; MCPA6 transformed from α crystal to γ crystal structure partly. The zeolite played a role of heterogeneous nucleation agent which improved the crystallinity of MC nylon 6. When the addition of zeolite was 5 phr, the zeolite / MCPA6 composite crystallization temperature increased over MCPA6 6.8 °C.

Research into the Preparation and Performance of Hydrotalcite/ MC Nylon 6 by <i>In Situ</i> Intercalation Polymerization

Hydrotalcite (LDHs) / MC nylon 6 composites were prepared by in- situ intercalation polymerization, followed by morphology and mechanical properties’ characterization of composites. FTIR shows that chemical structure of the molecular chain of the MC nylon 6 is not changed with adding hydrotalcite; SEM reveales that LDHs (2.5, wt-%) has good dispersion and compatibility in the MC nylon 6 matrixes; but when the amount of LDHs is excessive, the composites show obvious phase separation phenomenon. Hydrotalcite can significantly improve the mechanical properties of the composites. When the amount of hydrotalcite reaches 2.5% (wt-%), the composite has best comprehensive mechanical performance. Comparing with untreated MCPA6, the tensile strength and notched Izod impact strength are respectively increased by 68 % and 53 %.

<i>In Situ</i> Polymerization Organic-Inorganic Hybrid Materials Monomer Casting Polyamide 6/ Nanorods Yttrium Hydroxide

Single crystalline Y(OH)3 nanorods were synthesized from Y2O3 powder by a simple hydrothermal synthesis method under alkaline conditions. SEM images displayed that the nanorods have average diameters of about 400nm and lengths up to several micrometers. In this paper, it is used nano-inorganic particles yttrium hydroxide to modified MC nylon. The different mass fraction of yttrium hydroxide has affected mechanical and thermal properties of the MC nylon composites. The results show that with increasing of the mass fraction of yttrium hydroxide, the impact strength is the highest value when yttrium hydroxide mass fraction of 0.25wt%, however the tensile strength decrease 20%. And there is a little change in thermal stability when Yttrium Hydroxide added.

Research on Friction and Wear Properties of MC Nylon/ Carbon Nanotubes Composites

In this article, MC nylon/carbon nano tubes (CNTs) composites were prepared by in-situ polymerization method. The friction and wear properties were determined. The sample wear surface morphology carried out by scanning electron microscope (SEM) and the wear mechanism was investigated. It was found that the friction coefficient of composites has decreased with the amount of CNTs increasing in the composites. Addition amount of CNTs is up to 0.3% (weight percent), abrasion index decreased to minimum. The abrasion index of the sample of wearing a long time is smaller than that of the sample of wearing a short time. The sample with wearing less time mainly take place adhesive wear, however, mainly happen abrasive wear and adhesive wear for wearing time is longer. Further more, carbon nano tubes (CNTs) are not only improve the wear resistance of composites but also improve the mechanics performance.

상용 MC Nylon계 고분자 재료에서 초음파 특성의 온도 및 주파수 의존성

본 연구에서는 상용화된 monomer-cast nylon (MC nylon)계 고분자 재료로 만든 6종류의 시편에 대하여 감쇠계수 및 위상속도와 같은 초음파 특성의 온도 및 주파수 의존성을 조사하였다. 시편의 초음파 특성은 수중에서 2 MHz부터 8 MHz까지의 광대역 주파수 범위에 대하여 펄스투과법을 이용하여 측정하였다. 수온은 <TEX>$10^{\circ}C$</TEX>부터 <TEX>$60^{\circ}C$</TEX>까지 <TEX>$10^{\circ}C$</TEX> 간격으로 변화시켰다. 측정에 사용된 모든 시편에서 감쇠계수는 주파수가 증가함에 따라 증가하였으며, 주파수의 지수 의존성 n이 선형 (n=1)에서 약간 벗어난 1.16부터 1.44이내의 값을 가졌다. 위상속도는 <TEX>$60^{\circ}C$</TEX>에서 ivory 시편을 제외한 모든 경우에 대하여 주파수가 증가함에 따라 감소하는 음의 분산 특성을 나타냈다. 주파수에 의존하는 위상속도는 모든 시편에서 온도가 증가함에 따라 감소하는 특성을 나타내었다. In the present study, temperature and frequency dependences of ultrasonic properties such as attenuation coefficient and phase velocity was investigated for six kinds of commercial MC-Nylon polymer samples. The ultrasonic properties of the samples were measured by using a pulse transmission method in water over a broadband frequency range of 2 to 8 MHz. Water temperature was varied from 10 to <TEX>$60^{\circ}C$</TEX> with the <TEX>$10^{\circ}C$</TEX> interval. The attenuation coefficients of the samples increased with the frequency and the exponent n of frequency dependence ranged within 1.16 to 1.44, slightly deviating from the linear dependence (n=1). The phase velocities of the samples exhibited negative dispersion, i.e., decreasing velocity with increasing frequency, except for ivory sample at <TEX>$60^{\circ}C$</TEX>. The frequency-dependent phase velocities of the samples showed the decreasing tendency with increasing temperature.

Effect of Heat Treatment on the Structure and Properties of MC Nylon 6

Monomer casting nylon 6 (MC nylon 6) was fabricated by means of a cast moulding technique via the mechanism of anionic ring-opening polymerization, and the effect of heat treatment on the structure and properties of MC nylon 6 were studied. It was found that the heat treatment both in water and oil can improve the crystallinity of MC nylon 6; however, during the process of water heat treatment, the absorbed water in the sample may act as plasticizer, resulting in the remarkable difference in the physical and mechanical properties before and after heat treatment.

Tribological behavior of MC Nylon6 composites filled with glass fiber and fly ash

To improve tribological property of MC Nylon6, the glass fiber and fly ash reinforced monomer casting nylon composites (GFFAPA) were prepared by anionic polymerization of ɛ-caprolactam. The friction and wear behaviors of composites under dry condition, water lubrication and oil lubrication were investigated through a ring-black wear tester. Worn surfaces were analyzed using a scanning electron microscope. The experimental results show that the tensile strength and hardness of nylon composites are obviously improved with reinforcement increasing. Compared to MC nylon, the lowest friction coefficient and wear rate of glass fiber reinforced nylon composites (GFPA) with GF30% respectively decrease by 33.1% and 65.3%, of fly ash reinforced nylon composites (FAPA) with FA20% decrease by 5.2% and 68.9% and of GFFAPA composites with GF30% and FA10% decrease by 57.8% and 89.9%. The main wear mechanisms of FAPA composites are adhesive and abrasive wear and of GFPA composites with high proportion are abrasive and fatigue wear. The worn surfaces of GFFAPA composites are much multiplex and the optional distributing glass fiber and fly ash have a synergetic effect on the wear resistance for GFFAPA composites. Compared with dry friction, the friction coefficient and wear rate under oil lubricated conditions decrease sharply while the latter reversely increase under water lubricated conditions. The wear mechanisms under water lubricated condition are principally chemical corrosion wear and abrasive wear and they become boundary friction under oil lubricated condition.

Torsional Wear Behavior of MC Nylon Composites Reinforced with GF: Effect of Angular Displacement

The torsional wear behavior of monomer cast nylon (MC nylon) composites reinforced with glass fiber was studied with a self-made torsional friction tester. The worn surface of MC nylon composites was investigated with a scanning electron microscope. The worn surface of the steel disk was observed with a 3-D profiler. The experimental results indicated that the shape of torque–angular displacement (T–θ) curves changed from elliptic shape to quasi-parallelogram with the angular displacement increased from 5° to 30°. The serious wear characterized with a deep groove occurred at the position of about 1.5–4 mm radius of contact zone on the steel surface. The mass of MC nylon samples increased after torsional wear test. The torsional contact area can be divided into three zones: (a) a central stick zone, (b) an intermediate mixed-slipping annulus, and (c) a peripheral sliding annulus. The most serious wear occurred in the intermediate annulus because of the higher contact stress and mixed slip regime. The main wear mechanism of MC nylon samples was adhesive wear and abrasive wear. Plastic deformation of asperities was the character in the central zone. Slight adhesive wear was the main wear mechanism in the peripheral annulus.

Research on Water-Lubricated Bearing Applied in Propulsion Improvement of Certain Type of Motorboat

With energy price and environmental pressure increasing, water-lubricated bearing has been further applied in ship propulsion system. By analyzing structure characteristic of propulsion system, especially propeller shaft system of the certain type of motorboat, the improving design is proposed that water-lubricated bearing made by new improved material of MC nylon is used to substitute the oil-lubricated bearing. The abrasion characteristics test for improved motorboat bearing is made, which is analyzed by way of comparison with material sample test to predict useful life, and its environmental suitability analyzed. The results show that the bearing improvement of motorboat propulsion system has met the using requirements, and improved propulsion reliability, lowered fuel consumption, avoided water pollution, saved maintenance costs, and been the significant social and economic benefits.

Fabrication and Operation Testing of an Air-cored Pulse Transformer for Charging a High Voltage Pulse Forming Line

A high voltage air-cored helical strip/wire type pulse transformer has been fabricated for charging of a high voltage pulse forming line. As a primary coil, copper strip of 25mm width was wound helically around a MC nylon cylinder. For a secondary coil, copper enameled wire of 1mm diameter was wound around conical cylinder in order to provide insulation between two windings. The coupling coefficient of 0.53 was obtained when two coils were combined coaxially in the insulation oil filled chamber. Voltage gain and energy transfer efficiency were investigated by varying the parameters of primary and secondary circuit. Test results shows that the voltage gain increases up to 17 with increasing the primary capacitance up to 200nF. And highest energy transfer efficiency of 44% was obtained when the dual resonant operation condition was nearly satisfied. The pulse transformer developed in this study can be used for charging the middle conductor of a Blumlein pulse forming line.

Structure and Micromorphology of Wear Debris of MC Nylon 6 under Dry Sliding: Correlation with Wear Mechanisms

The structure and micromorphology of wear debris of MC nylon 6 under dry sliding were investigated by FTIR, XRD, DSC, and FESEM, and the 3D surface topographies of friction materials before and after the friction test were observed, which will be helpful in understanding the friction and wear processes. The primary crystalline phase of both the unworn MC nylon 6 and the wear debris were α crystal, but the crystallinity of the latter was higher than that of the former. The proportion of α 2 (002 + 202) planes increased and the reflection from the α 1 (200) planes was suppressed in the wear debris, indicating a preferential arrangement of α 2 (002 + 202) on the surface of the wear debris. The transition in structure of the wear debris originated from the activation of the chain segments due to the thermodynamic effects. The thermodynamic effects and high chain segment mobility resulted in the hydrogen bonding whose interchain distance is a larger rupture or even chain scission. MC nylon 6 was severely worn due to the contribution of the tearing force that resulted from the combined action of the tribo-interface adhesion and the shearing effect during friction, whereas no damage happened on the worn surface of the counterpart steel pin even if under severe sliding conditions.

Effect of carbon black on triboelectrification electrostatic potential of MC nylon composites

The triboelectrification electrostatic potential (TEP) of neat MC nylon and MC nylon composites were investigated under dry sliding and dry rolling, respectively, and the effect of carbon black (CB) and mechanisms of anti-triboelectrification of composites were studied. The incorporation of CB with proper fractions made considerable contributions to reduce and stabilize the TEP and to control the electrical resistivity of composites. The TEP of neat MC nylon is easily influenced by friction operating parameters, while the external conditions almost have no influence on the TEP of composites. It is the conductive paths that play the dominant role in composites.

Triboelectrification Electrostatic Potential of MC Nylon 6 under Point Contact Dry Sliding

The triboelectrification electrostatic potential of MC nylon 6 and its influence factors have not been investigated to date. Here, we report on our study of the interaction of tribological behaviors and triboelectrification electrostatic potential for the prevention or application of triboelectrification. The equipment we used to polymerize insulation materials and for instantaneously monitoring the dynamic variations of triboelectrification electrostatic potential, friction coefficient, and temperature at the tribo-interface was self-designed. The dynamic variations in the triboelectrification electrostatic potential of the polymer insulation materials under dry sliding were investigated using this equipment. An obvious influence on magnitude and change tendency of the triboelectrification electrostatic potential of MC nylon 6 could be produced only when the combined action of load (P) and speed (V) made PV values reach a certain degree. After MC nylon 6 rubbing against the bearing steel, the triboelectrification electrostatic potential of MC nylon 6 was not constant, and it could even abruptly drop from hundreds of volts to 0, especially under severe sliding conditions. A positive charge existed on the tribo-surface of MC nylon 6 and a negative charge existed on the tribo-surface of the counterpart steel. During the severe wear process, the experimental conditions, wear rate, the formation of transfer film, and the fraction of film on the counterpart as well as frictional heat were the most significant interaction effects on the abrupt change in the triboelectrification electrostatic potential among all factors studied. The interaction of tribological behaviors and triboelectrification electrostatic potential was clearly not a simple physical mechanism, which might be influenced by the external conditions and internal integration.

Isothermal and nonisothermal crystallization kinetics of MC nylon and polyazomethine/MC nylon composites

AbstractCrystallization kinetics of MC nylon (PA6) and polyazomethine (PAM)/MC nylon (PAM/PA6) both have been isothermally and nonisothermally investigated by different scanning calorimetry (DSC). Two stages of crystallization are observed, including primary crystallization and secondary crystallization. The Avrami equation and Mo's modified method can describe the primary stage of isothermal and nonisothermal crystallization of PA6 and PAM/PA6 composite, respectively. In the isothermal crystallization process, the values of the Avrami exponent are obtained, which range from 1.70 to 3.28, indicating an average contribution of simultaneous occurrence of various types of nucleation and growth of crystallization. The equilibrium melting point of PA6 is enhanced with the addition of a small amount of rigid rod polymer chains (PAM). In the nonisothermal crystallization process, we obtain a convenient method to analyze the nonisothermal crystallization kinetics of PA6 and PAM/PA6 composites by using Mo's method combined with the Avrami and Ozawa equations. In the meanwhile, the activation energies are determined to be −306.62 and −414.81 KJ/mol for PA6 and PAM/PA6 (5 wt %) composite in nonisothermal crystallization process from the Kissinger method. Analyzing the crystallization half‐time of isothermal and nonisothermal conditions, the over rate of crystallization is increased significantly in samples with a small content of PAM, which seems to result from the increased nucleation density due to the presence of PAM rigid rod chain polymer. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 2844–2855, 2004

Preparation and properties of three-dimensionally braided carbon fiber–MC nylon composites

Preparation and properties of three-dimensionally braided carbon fiber–MC nylon composites

FRICTION AND WEAR BEHAVIORS OF TOUGHENED POLYOXYMETHYLENE BLEND UNDER WATER LUBRICATION

This article describes the results from an experimental investigation on the friction and wear performances of the toughened polyoxymethylene/polyurethane blend (M-POM) under water drops lubrication. The sliding experiments were carried out on a block-on-ring tribometer. The contact configuration used was a stationary polymer block on a rotating AISI 1045 steel or MC nylon ring. The selected test material includes a polyoxymethylene (POM)-based composite that was toughened by polyurethane (PU) and filled by polytetrafluoroethylene (PTFE) and silicone oil. The results show that the M-POM with 10% PU (by weight) has better antifriction and antiwear properties under water drops lubrication, compared with pure POM and the POM/PTFE composite. The M-POM is more suitable to slide against MC nylon than steel under water lubrication. Because of the entrance of water, the hydrogen bond formed between water and polymers at the frictional surfaces during friction improves greatly the water lubrication performance of M-POM, in addition to the water-cooling action.

Tribological behaviour of modified polyacetal against MC nylon without lubrication

Compared with other polymers, polyacetal or polyoxymethylene (POM) which is widely used as bearing, guide, gear and other sliding parts, has high strength and stiffness, excellent chemical resistance and superior antifriction and wear resistance. To improve the toughness and self‐lubrication capacity of POM due to its higher crystallizability, other components, which include toughening phase and solid lubricants, are often added to the POM matrix. This paper deals with the friction and wear behaviours of POM which was modified by the toughening phase polyurethane (PU) and filled with polytetrafluoroethylene (PTFE) and silicone oil, during rubbing against MC nylon without liquid lubrication. Friction and wear tests show the tribological performance of the modified POM (M‐POM) with 10 wt% PU is better than those of pure POM and POM blended with PTFE under dry friction. The frictional coefficient of the M‐POM decreases with increasing nominal load. The sliding velocity has a more obvious effect on the tribological properties of the M‐POM than the nominal load. The higher sliding velocity leads to thermal degradation and melting of the experimental polymers because of the frictional heat.

Some Heterocyclic Polymers and Polysiloxanes

Aromatic heterocyclic polymers and polysiloxanes exhibit excellent thermal, mechanical, and insulating properties, having both wide and good potential use as multipurpose structural and functional materials in aerospace, electronic, manufacturing, and chemical industries. This paper briefly reviews our research work on several important aromatic heterocyclic polymers: polyphenylquinoxalines (PPQs), polytriazines (PPTs), polypyrrolones (PYs), polyimides (PIs), polyamide-imides (PAIs), polybenzimidazoles (PBIs); and polysiloxane. Either all or some of them can meet the needs in the above-mentioned high-technology areas. It is believed that the research work and applications of these polymers will be continually developed in the future. We focused our attention on (1) the syntheses of new monomers and polymers; (2) development of new synthetic routes; (3) discovery of new properties of polymers; (4) modification of monomer casting nylon (MC nylon, polycaprolactam) by these polymers and even heterocyclic compounds; (5) study of the mechanism of thermal degradation, pyrolysis, and hydrolysis at high temperature; (6) applications; and (7) conclusions.

Estimate of Antistatic Plastic used as Gear Material.

Antistatic plastic is one of the functional plastics which have been developed recently, but their characteristics when they are used as machine parts have not yet been elucidated. Consequently, various problems have occurred in their practical use. Therefore, in this study, gears were made of two kinds of antistatic plastics which were compounded by filling a conductible agent into matrixes of nylon (MC nylon) and polyacetal (copolymer), which are typical engineering plastics, and operation tests were conducted. The characteristics of the wear of teeth, the change of tooth profile and so on were examined, and the practicality of these plastics as gear materials was evaluated.