Wahit, M.U., Lim, J.W., Hassan, A. and Mohd Ishak, Z.A. (2004). Polyamide6/ PolypropyleneBlends Nanocomposites : The Effect of Blend Ratio on the Mechanical Properties. 1st National Postgraduate Colloquium. School of Chemical Engineering. USM, 96-104.
was initially obtained at the ratio of 90:10 wt % . The derived agglomerate was dried in vacuum at 80°C and mechanically mixed with polypropylene at ratios of 5:95, 15:85, 30:70 wt %. The blends obtained were plasticized by the method described in literature . The last stage was obtaining samples by the injection mold- ing under investigation in the form of standard blades applying the Kuasy 32/25 injection mold- ing machine following the optimal technological parameters: temperatures in zones of the injec- tor’s heating cylinder – 170, 195, 235°C; tem- perature of the injection mould – 68-70°С; in- jection pressure – 100 MPa; injection boost time – 6 s; cooling time – 25 s.
Most of the mechanical studies on MFC were made with systems based on polyolefin matrices [low-density polyethylene (LDPE), HDPE, or polypropylene (PP)], reinforced by virgin of recycled poly(ethylene terephthalate) (PET) microfibrils. Thus, MFC obtained from LDPE/PET oriented blends selectively isotropized by injection molding achieved elastic moduli approaching those of LDPE+30% glass fibers. The tensile strength of MFC has reached at least two times that of the neat LDPE matrix material, the impact strength of the MFC being 50% higher . Extensive mechanical studies have also been performed with the PP/PET [9, 20] and HDPE/PET MFC [21, 22]. HDPE/PA12 MFCs have also been obtained and characterized in tensile mode , observing a 74% improvement of the ultimate strength and a maximum of 43% improvement in the Young’s modulus, when compared with HDPE. It should be noted that these results were obtained with a single MFC (HDPE/PA12/YP ¼ 70/ 20/10 wt %), i.e., without any optimization of composition. The tribological properties of polyolefin matrices reinforced by PET or PA6,6 were also studied . It was established that the reinforcement with PA66 fibrils leads to higher wear resistance in comparison to PET in MFC with the same matrix material. The wear rates were found to be much lower in MFC with uniaxialy oriented reinforcing fibrils when compared to materials with random orientation of the reinforcements.
Figures 8(a) and 9(a) represent starch content at 10 wt. % in which starch is less visible due to poor dispersion of the starch in the PP matrix. However, a minimal effect was observed in Fig 9(a) due to the presence of compatibilizer. On the other hand, Figures 8(b) and 9(b) represent starch content at 50 wt. % in which the starch particles are evidently visible; an indication that the particles of the starch are not completely covered by the matrix as displayed in Fig. 8(b), but a better distribution of starch in PP matrix was seen. This validated the improvement of tensile properties of PS/PP blends on the incorporation of PP-g-MA. As can be seen from the micrographs, majority of the starch particles seem to disappear because of microbial attack after 90 days of soil burial. This leaves a blend with a surface full of holes which appear very significant with increase in starch content as shown in Fig.9 (b) for starch content at 50 wt. %.
To minimize the effects of moisture, PA6 was firstly dried in a vacuum oven for 24 h at 80 C prior to the melt blending. The melt-reactive blending process for preparing TPV samples (PA6: EDPM=50: 50 wt%) was carried out in an XSS-300 torque rheometer (Shanghai Kechuang Rubber Plastics Machinery Set Ltd, China) with a rotor speed of 30 rpm and a set temperature of 250 °C. PA6 and EPDM were first added in the mixer, and after 2.5 min, PF (1 wt%, 2 wt%, 4 wt% and 6 wt% to the total weight of the blends) was added and melt-reactive blending was continued for another 4 min. At last, the mixture was taken out and cut up. For the sake of brevity, TPVs with different PF loading were designated as TPV1 (1 wt%), TPV2 (2 wt%), TPV4 (4 wt%) and TPV6 (6 wt%), respectively. Also, PA6/EPDM blends without PF loading were named as TPV0, were prepared with the same procedure and processing parameters for comparison. The mixtures were compression-molded into sheets with a thickness of about 1.0 mm at 240 °C for 10 min under a pressure of 10 MPa.
Table II summarizes combustion parameters of the electrospun nanofiber membranes measured using the Micro-scale Combustion Calorimeter (MCC). Those include Heat Release Capacity, Peak Heat Release Rate (PHRR), and Total Heat Release. Compared to neat PA6, all FR-PA6 nanofiber films achieved significantly reduced heat-release parameters, indicating enhanced flame-retardant properties. For instance, the material’s Peak Heat Release Rate (PHRR) decreases significantly when FR loading is increased from 0wt% (PHRR = 655.5 w/g) to 15wt% (PHRR = 428 w/g). The addition of nanoparticles into the 15wt% FR-loaded PA6 further reduced PHRR to 385.2 w/g in the case of nanoclay and to 380.5 in the case of MWNT (Table II, Figure 4). The results observed for heat release capacity follow a similar pattern (Figure 5). On the other hand, Total Heat Release was reduced significantly with the addition of FR particles, but did not appear to be significantly affected by the nanoparticles (Figure 6). This result underscores the conclusion by Morgan & Wilkie  that nano-fillers alone have little chance of yielding a flame-retardant material that meets industrial standards. Our results show that it is the combination of the nano-fillers with intumescent particles that results in both effectively slowing the combustion (reduced heat release rate) and reducing the total heat release.
Different toughening mechanisms such as mechanical damping hypothesis , micro crack theory by Merz et al. in 1956 , multiple crazing theory by Bucknall and Smith in 1965 , shear yielding theory by Newman and Strella  have been proposed to improve the toughness of polymer composites. Since the cavitation of particles plays an important role in the toughening of rubber filled plastics, a prediction of the cavity initiation is a matter of concern. In this section, the cavitation criteria are introduced. A model of particle cavitation is advanced by Lazzeri and Bucknall . Two assumed preconditions are
Hence based on the literature survey, in our present study an attempt has been made to prepare the glutaraldehyde crosslinked ternary polymeric blends of nanochitosan with polyurethane foam and polypropylene glycol and ion addition the antioxidant property of prepared glutaraldehyde crosslinked nanochitosan/polyurethane foam/poly propylene glycol (1:1:1 ratio) antioxidant activity were evaluated and the results were discussed. PPG was used as the sole polyol to react with NCS and followed by this the chemistry of pre-polymer is altered by the functionalization of final PU foam using a chain extender. DPPH (2,2- diphenyl-1-picryl-hydrazyl-hydrate) free radical method is an antioxidant assay based on electron-transfer that produces a violet solution in ethanol.  This free radical, stable at room temperature, is reduced in the presence of an antioxidant molecule, giving rise to colorless ethanol solution. The use of the dPPH assay provides an easy and rapid way to evaluate antioxidants by spectrophotometry,  so it can be useful to assess various products at a time. The percentage of antioxidant activity (aa%) of each substance was assessed by DPPH free radical assay. The measurement of the DPPH radical scavenging activity was performed according to methodology described by Brand-Williams et al.  The prepared novel blends was characterized using FT-IR, XRD and SEM analysis. The results were discussed below.
This discussion shows that although nanoclays in presence of compatibilisers are effective in reducing flammability of polypropylene, but they do not do so to the same extent as seen for other polymer-nanocomposites systems. It must also be noted that these are thermally and physically thin samples and behave differently than bulk polymers, which are tested as thick plaques. It is believed that in polymer-nanoclay nano/micro composites, a carbonaceous-silicate char builds up on the polymer surface during burning, which insulates the underlying material and slows the mass loss rate of decomposition products, hence conferring flame retardant property to the polymer. 17 The poor performance of the thinner samples may be explained in terms of a competition between the formation of a surface carbonaceous-silica shield and the volatilisation to fuel of surrounding polymer. In thicker polymer-nancomposite samples, the competition favours ceramic barrier formation while for thin composites, volatilisation dominates. This can be considered as the difference between so-called thick and thin thermal behaviour 17 and so in similarly “thin” films or textile fabrics it is possible that the “shield-forming” mechanism observed for bulk polymer nanocomposites may be too slow for effective improvement in fire performance.
A novel charring agent, poly(p-ethylene terephthalamide) (PETA), for halogen-free flame retardant polypropylene was synthesized by using p-phthaloyl chloride (TPC) and ethylenediamine through solution polycondensation at low temperature, and the effects of PETA on flame retardance of polypropylene (PP)/IFR systems were studied. The experimental results showed that PETA could considerably enhance the fire retardant performance as proved by evidence of the increase of limiting oxygen index (LOI) values, the results of UL-94 tests, and cone calorimeter tests (CCT). Fourier transform infrared spectroscopy (FTIR) and scanning electron microscope (SEM) demonstrated that an appropriate amount of PETA could react with PP/IFR system to form cross-link network; a more compact char layer could be formed which was responsible for the improved thermal and flame retardant properties of PP/IFR systems. However, the superfluous amount of PETA would play the negative role.
The thermal and flammability properties of polyamide6/clay (2 and 5% by mass fraction) nanocomposites were measured to determine their flame retardant (FR) performance. The gasification process of the nanocomposite samples at an external radiant flux of 50 kW/m 2 in a nitrogen atmosphere was observed, and the residues collected at various sample mass losses were analyzed by thermogravimetric analysis, transmission electron microscopy, and X-ray diffraction to determine the content of the residue and to understand the FR mechanism of the nanocomposites. The analysis of the floccules of blackened residues shows that up to 80% by mass of the residues consists of clay particles and the remainder is thermally stable organic components with possible graphitic structure. Furthermore, clay particles are stacked in the carbonaceous floccule residues and the d-spacing of the clay platelets is in the range of 1.3 – 1.4 nm as compared to the well exfoliated original sample. The accumulation of the initially well-dispersed clay particles in the sample on the burning/gasifying sample surface are due to two possible mechanisms. One is recession of the polymer resin from the surface by pyrolysis with the de-wetted clay particles left behind. Another mechanism is the transportation of clay particles pushed by numerous rising bubbles of degradation products and the associated convection flow in the melt from the interior of the sample toward the sample surface. Numerous rising bubbles may have another effect on the transport of clay particles. Bursting of the bubbles at the sample surface pushes the accumulated clay particles outward from the bursting area and forms the island-like floccules instead of forming a continuous net-like structure of a clay filled protective layer. Therefore, both PA6/clay nanocomposite samples did not produce sufficient amounts of protective floccules to cover the entire sample surface and vigorous bubbling was observed over the sample surface which was not covered by the protective floccules.
5. Manikandan, P., Varga, J., Kocsubé, S., Anita, R., Revathi, R., Németh, T.M., Narendran, V., Vágvölgyi, C., Panneer S.K., Shobana, C.S., Babu Singh, Y.R., Kredics, L. Epidemiology of Aspergillus keratitis at a tertiary care eye hospital in South India and antifungal susceptibilities of the causative agents. Mycoses., 2012; 56: 26-33. 6. Bharathi, M.J., Ramakrishnan, R., Vasu, S., Meenakshi, R., Palaniappan, R. Aetiological diagnosis of microbial keratitis in South India - A study of 1618 cases. Indian J. Med. Microbiol., 2002; 20: 19-24.
Abstract. Polyamide (PA6) nanocomposites containing 4 wt% organo-montmorillonite (OMMT) were melt-compounded followed by injection molding. The mechanical properties of the PA6/OMMT nanocomposites were studied through tensile and flexural tests. The rheological behaviour of the nanocomposites was determined by plate/plate rheological measure- ments. Attempts were made to trace the rheological parameters that reliably reflect the observed changes in the clay disper- sion. X-ray diffraction (XRD) and atomic force microscopy (AFM) were used to characterize the exfoliation and dispersion of the OMMT in the PA6 matrix. The thermal properties of PA6/OMMT nanocomposite were characterized by Dynamic Mechanical Thermal Analysis (DMTA). The tensile modulus and strength of the PA6 was increased in the presence of OMMT. The flexural strength of PA6/OMMT was approximately doubled compared to the tensile strength value. The sig- nificant enhancement of both tensile and flexural strength was attributed to the delaminated clay formation. XRD and AFM results revealed the formation of PA6 nanocomposites as the OMMT was successfully exfoliated.
Thailand is one of the major countries in the world for pineapple production [2,6]. Tons of pineapple leaf have become agricultural wastes after harvesting which have been interested for value adding. Pineapple leaf fiber (PALF) consists of cellulose about 70-80 %wt giving its high specific modulus and strength [2,4,7]. It can be an efficient reinforcement for different polymers [2,7-9] after its surface improvement with coupling agent. Compatibility of the components within the composites especially at the interfacial region, where stress transfer occurred, plays an important role for mechanical properties of the composite materials. Amornsakchai T. et al [2,10] has introduced a new extraction method called mechanical milling for preparing PALF. This method has ability to produce high yield, fine and short PALF to reinforce polypropylene with development in mechanical properties as well as heat distortion temperature.
The dielectric constant of o-Cresol–PA6 mixture, the values are quite low compared to m-Cresol and p-Cresol. Due to the presence of methyl group in ortho position, the intra molecular H- bond interaction of o-Cresol is high. In addition steric effect also occurs within o-Cresol. The combined effects led to decrease in the molecular interaction between PA6 and o-Cresol (Fig.5). Hence it has been shown that the PA 6 with o-Cresol mixture was giving low dielectric constant and relaxation time.
The purpose of this study was to obtain polyamide-6 nanocomposites with national organically modified clay (termed 12-montmorillonite). The formation of polyamide-6 was confirmed by infrared spectroscopy (IR), the prepared nanocomposites were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and thermogravimetric analysis (TGA). The evolution of mechanical properties was also studied. The obtained results confirm the intercalation of molecules of salt in the clay layers, and a good interaction with the polymer, showing the formation of intercalated and/or partially exfoliated structures. The nanocomposites showed higher thermal stability compared to pure polymer, and the mechanical properties presented interesting and promising results.
Long branches on PP backbone increase molecular entanglements and enhance melt strength. Numer- ous attempts have been made to produce long-chain branched polypropylene directly using constrained metallocene catalysts [3, 4, 5] or by grafting process. Grafting of long chain branches onto linear backbone is the most commercially attractive and efficient way to enhance the melt strength of linear polymers like poly (ethylenetherphetalate)  and polypropylene [7, 8]. It can be carried out by using ionizing irradia- tion, such as electron beam or gamma ray radiation  or with using peroxides and free radical co-agents via reactive extrusion process [7, 9]. Chain-scission, crosslinking and grafting are the competing reactions during grafting process, resulting in branching struc- tures. It has been proposed that the chain-scission and degradation reactions in the radical functionalization of PP can be controlled by using co-agents, such as furan and thiophene derivatives. It is found that these agents significantly prevent the decrease in molecu- lar weight of PP by grafting onto the backbone and promote the reaction with the macro-radicals formed through H-abstraction [10, 11].
Polystyrene (PS) has high thermal resistance thus can be applied as thermally comfort- able textile. However, the application is limited due its low mechanical strength. In this study, polyamide6 (PA6) was blended with PS to improve the mechanical strength of PS, by means of a multi-jet electrospinning. Content ratio of the blend web was measured by chemical immersion test and confocal microscopy analysis. Fiber content was in accordance with the number of syringes used for PS and PA6 respectively. The effects of content ratio on the web morphology, thermal resistance, tensile behavior, air and water vapor permeability, and surface hydrophilicity were investigated. The influence of environmental humidity during electrospinning process on three dimen- sional (3D) web structure was also reported. PS web produced from higher humidity had more pores and corrugations at the surface. The increased surface roughness and porosity led to the increased hydrophobicity and thermal resistance. Though the blending of PA6 with PS enhanced the mechanical strength, the added PA6 decreased air/water vapor permeability and thermal resistance. The lowered thermal resistance by the addition of PA6 was mainly attributed to higher thermal conductivity of PA6 mate- rial and lowered air content with PA6 fibers.
In the agricultural applications of structural materials show some typical environment for machine elements. Very often improved abrasion resistance is needed due to high dust content of the surroundings. In slideways ad transport systems of crops and grains the antistatic surface is important to avoid static charge and explosion. Further step is when the antistatic behaviour is not enough and fire-retardant or fire-safe polymer is required. Finally we decided to develop some new composite versions of magnesium catalytic cast polyamide6: