Statistical Study on Additives Used to Improve Mechanical Properties of Polypropylene

Polypropylene (PP) is a semi-crystalline polymer that is brittle under severe conditions. To meet industry needs, and to increase the applications of polypropylene, its mechanical properties should be improved. In this research, the mechanical properties of polypropylene, such as tensile strength at break, tensile strength at yield, % elongation, and Young’s modulus, were improved using two types of additives. Additives used were calcium carbonate master batch filler composed of 80% calcium carbonate and 20% polyethylene, and a mixture of linear low-density polyethylene (LLDPE)/low density polyethylene (LDPE). Results showed that both tensile strength at break, and tensile strength at yield, decrease with increasing the amount of both additives. Percentage elongation of PP increased using both additives. The modulus of elasticity of PP increases by increasing the amount of both additives, until a value of 20 wt%. Analysis of variance (ANOVA test) or (F-test) shows significant differences between the effect of different weights of LLDPE/LDPE mixture and calcium carbonate filler on the four mechanical properties of polypropylene studied at a level of 0.05. T-tests are applied to compare between the effect of both calcium carbonate master batch filler and the mixture LLDPE/LDPE on the four mechanical properties of polypropylene studied. T-tests show no significant differences between the effect of both calcium carbonate master batch filler and the mixture LLDPE/LDPE on all mechanical properties of polypropylene studied at a level of 0.05.

Longevity of Twelve Geomembranes in Chlorinated Water

The long-term performance of geomembranes with twelve different resin/antioxidant master-batch combinations, including eight HDPE, three linear low density polyethylene (LLDPE), and one blended polyolefin (BPO) base resins, is investigated. Results are reported for immersion tests in chlorinated water (0.5 ppm) for 35 months at 85oC. The degradation trends show that the choice of resin type played a key role in the longevity of the geomembranes but also that some hindered amine light stabilizer (HALS) packages contributed to better resistance to degradation in chlorinated water. The results show that the specific antioxidant package is more important than the initial oxidative induction time (OIT) in terms of long-term performance. Finally, it is shown that while increased thickness may be beneficial, a more resistant resin or antioxidant/stabilizes package can be more effective than increasing thickness in improving geomembrane performance in chlorinated water. The conclusion regarding the beneficial role of HALS is specific to chlorinated water and generally is not true in other cases of submerged or buried geomembranes.

Improvement of Mechanical and Rheological Properties of Natural Rubber for Anti-Vibration Applications

This research aims to study and improve the passivating specifications of rubber resistant to vibration. In this paper, seven different rubber recipes were prepared based on mixtures of natural rubber(NR) as an essential part in addition to the synthetic rubber (IIR, BRcis, SBR, CR)with different rates. Mechanical tests such as tensile strength, hardness, friction, resistance to compression, fatigue and creep testing in addition to the rheological test were performed. Furthermore, scanning electron microscopy (SEM)test was used to examine the structure morphology of rubber. After studying and analyzing the results, we found that, recipe containing (BRcis) of 40% from the natural rubber has the best mechanical and physical specifications to be used in applications that require the presence of rubber, resistant to vibration. Keywords: Ant vibration behavior , Natural rubber, Synthetic rubber, master batch.

Preparation PET Hybrided Materials by In Situ Polymerization for Delustered Fibers

A series of polyethylene terephthalate (PET) hybrid materials with high-load TiO2 content were prepared via in situ polymerization by dispersing unmodified titanium dioxide (TiO2) in Ethylene Glycol (EG), and the influence of load TiO2 nanofillers on the physical properties of PET masterbatch was investigated. The intrinsic viscosities of the prepared PET hybrid materials were affected by the addition of the nanoparticles and in both cases a slight decrease was observed. In addition, the thermal behavior of these PET hybrid materials and neat PET was investigated using Differential Scanning Calorimetry (DSC). The chemical structures of PET hybrid materials were characterized by Fourier Transform Infrared (FTIR) and Scanning Electron Microscopy (SEM). The TiO2 nanoparticles show well dispersibility in PET matrix. The PET hybrid material with 40wt.% TiO2 content was used as master batch to prepare full dull PET fiber with 2.5 wt.% TiO2. The melt flow ability of PET hybrid materials shows good winding and drawing performance, and also the resulted fiber has better mechanical properties than neat PET fiber. It suggests that this PET/TiO2 masterbatch by in situ polymerization may find good application for delustered fiber preparation.