The effect of fiber concentration on mechanical and thermal properties of fiber‐reinforced polypropylene composites

Abstract

A novel composite material consisting of polypropylene (PP) fibers in a random poly(propylene-coethylene) (PPE) matrix was prepared and its properties were evaluated. The thermal and mechanical properties of PP-PPE composites were studied by dynamic mechanical analysis (DMA) and differential scanning calorimetry (DSC) with reference to the fiber concentration. Although, by increasing PP fiber concentration in PPE, no significant difference was found in melting and crystallization temperatures of the PPE, the storage, and the tensile and flexural modulus of the composites increased linearly with fiber concentrations up to 50%, 1.5, 1.0, 1.3 GPa, respectively, which was approximately four times higher than that for the pure PPE. There is a shift in glass transition temperature of the composite with increasing fiber concentration in the composite and the damping peak became flatter, which indicates the effectiveness of fiber-matrix interaction. A higher concentration of long fibers (Ͼ50% w/w) resulted in fiber packing problems, difficulty in dispersion, and an increase in void content, which led to a reduction in modulus. Cox-Krenchel and Haplin-Tsai equations were used to predict tensile modulus of random fiber-reinforced composites. A ColeCole analysis was performed to understand the phase behavior of the composites. A master curve was constructed based on time-temperature superposition (TTS) by using data over the temperature range from Ϫ50 to 90°C, which allowed for the prediction of very long and short time behavior of the composite.

Evaluation of the Bending Strength, Impact Strength, and Morphological Properties of Wheat Straw Fiber/Paper Mill Sludge/Polypropylene Composites

“…The improvement in the combined ratio to PP matrix was 114%, which showed a dramatic improvement in the bending modulus of elasticity. An increase in the bending modulus composite PP/wheat straw fiber ratio to pure PP was attributed to higher stiffness, which represents the reinforcement properties of the wheat straw fiber in the matrix to the fiber stress of their transfer (Houshyar et al 2005). By adding paper mill sludge, the bending modulus of elasticity increased to higher hardness values.…”

Fabrication and mechanical properties of self-reinforced poly(ethylene terephthalate) composites

“…Presently manufacturers fabricate Armordon ® and Pure ® by applying the co-extrusion technique. Many studies have explored the film stacking method for manufacturing self-reinforced polymeric composites [15][16][27][28][29]. After producing the reinforced textile structure, it is sandwiched between films, which should overtake the role of the matrix after melting and subsequent cooling.…”

Polyamide 6 single polymer composites

“…In contrast to the foregoing approach, the most frequently used technique is film stacking where the film is generally chosen to have a lower melting temperature (T m ) compared to the orientated fibers [10][11][12][13][14][15][16]. A characteristic feature of this technique [10][11][12][13][14][15][16][17][18][19] is that the two constituents of the same polymer are used as starting materials for manufacturing of SPCs. Recently, the authors have explored both of these approaches for preparation of SPCs based on poly(ethylene terephthalate) (PET) using a new type of reinforcement, namely, PET nanofibrils, by means of techniques developed earlier [20,21] for nanofibrillar composites (NFCs).…”