Fatigue behavior of neat and long glass fiber (LGF) reinforced blends of nylon 66 and isotactic PP

Abstract

This paper focuses on the study of the fatigue behavior of neat and long glass fiber (LGF) reinforced nylon 66/PP‐blends. The fatigue was characterized using Parislaw plots in the stable crack growth acceleration range. The fatigue crack propagation (FCP) is presented as a function of the crack growth per cycle (da/dN), the amplitude of the stress intensity factor ΔK, and of the strain energy release rate ΔG. It was also of interest to compare the order of performance found in fatigue to that in the static fracture test. The fracture surfaces were characterized with SEM to determine the failure mechanisms. Further, thermographic camera recordings were used to study the size of a “heated” area (ΔT = 2°C) that developed around the crack tip during the cyclic loading of LGF‐PP with different amounts of maleic anhydride grafted PP (PP‐g‐MAH). For the neat materials, a different order of performance was detected under static and cyclic loading. This was explained by the different failure mechanisms observed after static and cyclic fracture that were related to different stress states of the specimens during the fracture process. On the other hand, the LGF‐blends showed a similar order of performance during the static and the fatigue test. This was explained by the observation that similar fiber related failure mechanisms occurred in the composite, both after failure caused by the static and cyclic loading, respectively. For the LGF‐PPs with varying PP‐g‐MAH content, the order of performance in fatigue did not correspond to the size of the “heated area” around the crack tip. This was caused by a change in the composite failure mechanisms, which contributed differently to the size of the “heated area” and to the fatigue performance.

Compósito de resina poliuretano derivada de óleo de mamona e fibras vegetais

“…Segundo Harmia (1996) quando as fibras estão orientadas paralelamente à direção de propagação da trinca observa-se principalmente descolamento das fibras, e quando elas estão orientadas perpendicularmente, deslizamento e fratura das fibras são observados.…”

A review of Long fibre thermoplastic (LFT) composites

“…In addition to their quasi-static material properties and impact performance, the creep behaviour [266][267][268][269][270][271], fatigue behaviour [6,51,[272][273][274][275], vibration behaviour [276], UV resistance [277], machinability [278,279], heat treatment [280], and rheological behaviour [56,58,96,199,[281][282][283][284], of LFT composites have Table 1. Mechanical properties of LFT composites.…”

“…LFTs with multi-matrix systems can gain the benefit of both the matrix polymers. For example, LFTs with a PP + PA66 matrix can benefit from the low water absorption and excellent processing properties of PP and the high mechanical strength and temperature resistance of PA66 [51].…”

“…Polyamide-based LFTs have about 20% of the market share and LFTs with other polymer systems comprise the remaining 15% [17]. Though single polymer systems are most commonly used as the matrix in LFTs, multiple polymer systems have also been studied such as TPU + POM [44], PP+ polystyrene (PS) [45], TPU + acrylonitrile butadiene styrene (ABS) [46], PBT + PET [47,48], polycarbonate + PBT [49], TPU + styrene acrylonitrile (SAN) [50], PA66 + PP [51,52], PP + PBT [53], and polyvinyl chloride (PVC)+PP [54]. LFTs with multi-matrix systems can gain the benefit of both the matrix polymers.…”

Correlation between compounding sequence and the properties of glass fiber‐Reinforced nylon‐6,6 composite

“…Depending on the composite system, especially for fiber/non‐polar polymers, such as polyolefins, a third component has been used to improve the adhesion between the polymer matrix and filler via interactions between functional groups of the GF surface and third component . However, the addition of a third component is not common for GF/polar polymer systems such as GF/polyamide.…”