Compounding of glass fiber-reinforced polypropylene and investigation of its mechanical properties under simple and complex loading

✍ Scribed by S. N. Pandit; V. B. Gupta; K. Subramanian

• Publisher: Society for Plastic Engineers
• Year: 1981
• Tongue: English
• Weight: 515 KB
• Volume: 2
• Category: Article
• ISSN: 0272-8397
• DOI: 10.1002/pc.750020205

✦ Synopsis

Abstract

Polypropylene is one of the important thermoplastics that has been reinforced with glass fibers to give a reasonably good engineering plastic. Because of its inert nature, it does not easily adhere to the glass surface and hence some improvement in mechanical properties. In the present study a vinyltriethoxysilane coupling agent in polymeric form has been tried and seen to improve the properties. Tests have been carried out at (a) constant strain rate (in the Instron testing machine), and (b)constant stress rate (water loading on a biaxial testing machine). Under constant strain rate only tensile properties have been studied while under constant stress rate, the tensile, torsional and combined tensile‐torsional tests have been carried out. In each of the above cases, a considerable improvement in elastic modulus has been observed. The Tensile strength is improved to the extent of about 25 percent. There is only a slight improvement in torsional strength. Different fiber volume contents were used and their effect studied on modulus and strength. The mechanical data for reinforced‐polypropylene samples have been discussed in terms of the fiber‐length distribution in the composite. Detailed analysis of tensile data suggests that at low strains, when the critical length is relatively low, the fibers contribute to a high modulus. With increasing strain the critical length increases and the load carrying capacity of the fibers is reduced. Consequently the gain in strength is relatively less. The effect of fiber length distribution in torsion and combined tension‐torsion tests would be expected to be similar and the results seem to confirm this.