Mechanical and Physical Properties of PP and HDPE

Abstract

The properties of these polymers, as in the case of any materials, depending on the molecular weight of the polymer and the structure of the polymer chains. The main objective of this work is to study the mechanical and physical properties of pure PP and HDPE. To obtain a full characterization of pure polymer, samples were produced using a compression molding technique. Polymeric samples successfully filled the cavity of the die. The mechanical properties of PP and HDPE were determined using three-point bending, compression, hardness and impact test. While the physical properties were studied through density and water absorption. Also, the thermal analysis behavior was determined by thermogravimetric analysis, differential scanning calorimetry and thermomechnical analysis. Results showed the structure affects the properties. The PP showed better elastic modulus and strength due to the methyl attached to the carbon that prevents the chain rotation and hence makes the material stronger but inflexible. On the other hand, the absorbed energy of PP is less than that of HDPE. The thermogravimetric analysis results show a single weight-loss event with a degradation temperature of 310°C for HDPE and 255°C for PP. The differential scanning calorimetry shows that the crystallinity of PP (≅51) is less than that for HDPE (≅68) due to the difference in the specific heat. The coefficient of thermal expansion of HDPE is higher than that of PP due to the stronger interatomic forces.

Influence of Recycled High-Density Polyethylene Fibers on the Mechanical and Electrochemical Properties of Reinforced Concrete

“…The results show HDPE fibers with a low water absorption percentage of around 0.255%, due to the hydrophobic nature of the HDPE fibers, and some material micro-cracks, and the HDPE recycled fibers' density is 0.955 g/cm 3 . These results are similar to those reported in the literature [22,33,37]. In Figure 3, the HDPE recycled fibers' direct stress-strain curve is observed, and the data on the mechanical properties are shown in Table 2.…”

“…Five samples, thirty fiber pieces each, were water-saturated for 24 h and weighed using a Denver Instrument 0.0001 g precision electronic balance. Samples were deposited in 50 mL probes, and distilled water was poured in a 30 mL gauge and calculated according to the ASTM D792 standard [32] using the following Equation (2) [33,34]:…”

Polyolefins and Polyethylene Terephthalate Package Wastes: Recycling and Use in Composites

“…Upon addition of PP, the Young's modulus and yield strength increased, but elongation at break and impact strength decreased. Hassan Awad et al [198] observed similar tensile property trends in rPP/rHDPE blends upon rPP addition. The crystallisation behaviour of PO blends is also affected by the recycling process.…”

Evaluation of the Effectiveness of Geogrids Manufactured from Recycled Plastics for Slope Stabilization—A Case Study

“…Finally, the results of Table 1 indicate that the T1 composite exhibited the highest resistance to deformation under tensile load, indicative of HDPE’s ductile nature [ 63 ]. Conversely, PP’s inclusion tends to reduce the material’s plasticity, making it more prone to deformation at lower loads due to its inherent brittleness.…”