Study On Properties Of Tremolite/Nylon1010 Composites

Incorporating inorganic mineral fillers into plastic resin is usually used to improve various physical properties of the materials, such as mechanical properties and heat deflection temperature etc. Also, the cost for the polymer products can be lowered by substitute the expensive resins with cheap fillers. Thus the field of particle-filled polymer composites has gained considerable attention. Polyamides are one of the most widely used engineering thermoplastics especially in machine, automotive, and electrical industries because of their excellent mechanical properties. However, the lower heat deflection temperature, higher water absorption, and dimensional instability of the pure nylon have prevented their applications as structural components. Numerous efforts have been made to utilize nylon as the matrix resin for composites by adding glass fibers or other inorganic fillers such as clay, montmorillonite, MoS2, Kaolin, Al2O3, carbon, mica, tremolite and so on.In a general way,the mechanical properties of particulate-filled polymer composites are dependent strongly upon dispersion of the filler in the matrix and adhesion at the filler/matrix interface. Because of the hydrophilic nature, the filler does not wet or interact interfacially with hydrophobic polymer due to the difference in surface energies. It is necessary to treat the filler with a coupling agent in order to improve the compatibility between filler and matrix. In this paper, tremolite (Ca2Mg5[(OH)Si4O11]2), a naturally occurring, cheap nonmetallic mineral was chosen as a filler to reinforce PA1010(Nylon1010). Prior to being incorporated into PA1010, tremolite was pretreated withγ-methacryloxypropyl trimethoxy silane (MPS). Modified or non-modified tremolite was mixed with PA1010 resin at different ratios and extruded on a twin-screw extruder and and then injection-molded on a screw injection-molding machine to prepare standard test specimens.In order to test the MPS on tremolite, MPS modified tremolite powder was extracted on a soxhlet with toluene for 12 hours before measurements. On IR spectra, band at 1720 cm-1 coming from the vibration of C=O bonds of the MPS. Another more convictive proof for the graft of MPS was provided by X-ray photoelectron spectroscopy. An evident change is that organic C (284.99 and 289.6244eV) appears attributed to C-H and C-O(C=O) that cannot be found before modification. A conclusion can be drawn that MPS has been grafted onto the surface of tremolite really.The addition of filler to Nylon1010 brings about an evident change in Young's modulus and elongation at break of composites. Young's modulus enhances sharply with the increase of the content of filler, and a drastic decrease of the break-strain can be seen for both modified and non-modified tremolite. Additionally, it can be found the break-strain of composites with modified tremolite is lower than that of non-modified tremolite, which is consistent with the enhancement of Young's modulus.In case of composites with the loading of MPS modified tremolite, the tensile strength is much higher than that of pure PA1010 matrix in the range of filler content. Furthermore, a maximum is achieved at a content of 10%, which increases 33.1% compare to PA1010 matrix. When the content is above 10%, the tensile strength has a little decrease and changes slowly, but it is still higher than that of pure matrix. The notched Izod impact strength degreases with increasing filler content in the case of non-modified tremolite composites. Whereas the modified composites are concerned, we can see that the strength is greater than that of non-modified ones, and a 22.6 % increase compared to pure PA1010 at filler content of 10%. Therefore, the optimum concentration of filler is 10%. SEM micrographs of the fractured surface with a filler content of 10% are shown that there is no aggregate in MPS-modified composites. On SEM micrographs of the tensile fracture surface of composites with MPS-modified tremolite, the particles are embedded partly in matrix. In addition, the particle surface is not smooth, there being filiform PA1010 remained on it. The matrix around the particles or wall of the cavities is irregular. It can be deduced that the adhesion between filler and PA1010 is reinforced markedly.Also the crystallization properties of Nylon1010 and its composites were investigated beside mechanical and thermal properties. Though the structure of crystal cell does not change, the crystallization behavior of Nylon1010 affected by tremolite.Isothermal crystallization results show that the rate of crystallization of tremolite/Nylon1010 is faster than that of pure Nylon. Avrami equation was used to analyze the data. Results show that n of tremolite/Nylon1010 is smaller than the one of pure Nylon1010. That is to say, the growth of crystal in Nylon1010 is changed by tremolite whether modified or not. The k decreases with crystal temperature's increasing. Crystallization activation energy is also calculatedfor Nylon1010 and its composites, and the value of the later is larger than that of the former. It is shown that composites T-40 and M-10 are sensitive to temperature mostly.During nonthermal crystallization, tremolite takes different place comparing with thermal cystallization. Results show tremolite facilitates Nylon1010 crystallization, but the course of cystallization itself is slow. Cystallization kinetics analysis reveals the growth of crystal in Nylon1010 is changed by tremolite whether modified or not. The value of F(T) to MPS modified tremolite is larger than that of pure tremolite filled Nylon1010, which means cystallization of MPS modified tremolite/nylon1010 is retarded distinctly. On DSC curves of Nylon1010 and its composites, double-melting peaks can be found. The crystallization temperature or cooling rate brings effect to the peak appearing at the lower temperature.In order to know the effect of tremolite to Nylon1010 rheological property, a Dynisco polymer test LCR7001 capillary rheometer is used. Results reveal Nylon1010 and its composites are pesudo plastic fluid. Under same condition, the apparent viscosity of MPS modified tremolite/Nylon1010 is smaller than its non- modified partner. Also, the appearance of MPS modified tremolite/Nylon1010 is slipperier than its non- modified partner. The quality of appearance is improved.