Tensile and impact properties of three-component PP/wood/elastomer composites

Abstract

Polypropylene (PP) was reinforced with wood flour and impact modified with elastomers to increase stiffness and impact resistance simultaneously. Elastomer content changed in four (0, 5, 10 and 20 wt%), while that of wood content in seven steps, the latter from 0 to 60 wt% in 10 wt% steps. Structure and adhesion were controlled by the addition of functionalized (maleated) polymers. Composites were homogenized in a twin-screw extruder and then injection molded to tensile bars. Fracture resistance was characterized by standard and instrumented impact tests. The results showed that the components are dispersed independently of each other even when a functionalized elastomer is used for impact modification, at least under the conditions of this study. Impact resistance does not change much as a function of wood content in PP/wood composites, but decreases drastically from the very high level of the PP/elastomer blend to almost the same value obtained without impact modifier in the three-component materials. Increasing stiffness and fiber related local deformation processes led to small fracture toughness at large wood content. Micromechanical deformation processes depend mainly on the strength of PP/wood interaction; debonding and pull-out take place at poor adhesion, while fiber fracture dominates when adhesion is strong. Composites with sufficiently large impact resistance cannot be prepared in the usual range of wood contents (50–60 wt%)

Effect of particle size, coupling agent and DDGS additions on Paulownia wood polypropylene composites

“…10,19,26,27,[29][30][31] Coupling agents act as intermediates to bind hydrophobic polyolefins to hydrophilic lignocellulosic materials (e.g., wood or DDGS). The mechanical testing results of the effect of the coupling agent concentration are graphically presented in Figure 1.…”

“…The MAPP is added to improve the adhesion of the hydrophobic wood particles to the hydrophilic PP matrix. 19 The main advantage of the MAPP will be to minimize incompatible surfaces, or discontinuities, between the reinforcement and the matrix. The net effect is to reduce the formation of microscopic cracks that can ultimately lead to failure either in tension or during impact.…”

“…Thus, this study was conducted utilizing PWF derived from juvenile tree biomass (i.e., 36-month-old). Coupling agents are commonly used with wood fiber polyethylene (PE) and PP composites, 9,16,18,19 so the benefit of adding a maleated PP (MAPP) was examined to determine an optimal level of loading. In addition, because particle size may affect the performance of a WPC, 9,20,21 different sized particles of PWF were tested in composites.…”

Non-uniform dispersion of toughening agents and its influence on the mechanical properties of polypropylene

“…A crosshead speed of 50 mm/min was applied to determine the tensile strength, elongation at break and tensile modulus. Conventional Izod tests can provide information on the impact resistance of materials during high strain rate deformation; no other valuable data can be obtained except the final impact strength, especially in the inhomogeneous filler distribution system [29,30]. Therefore, in this experiment, instrumented falling weight impact test (IFWIT) was used to detect the impact force changing trend versus displacement, establishing the correlation between filler distribution and impact strength IFWIT was performed on a TCJ-25 (Jilin Taihe Tester Co. Ltd, China) machine.…”

Bacterial Cellulose Nanofiber Reinforced Poly (lactic acid) Nanocomposite

“…Hence, the suitable interface Compatibilizer agent between the PLA matrices and BC nanofibers would lead to improving BC distribution. Meanwhile, BC contents reduced surface polarity when interacting with PLA and improved reinforced efficiency [9,10].…”