Experimental and theoretical approaches for structural and mechanical properties of novel side chain LCP-PP graft coproducts

Abstract

The monomers p-biphenyloxycarbonylphenyl acrylate (BPCPA) and p-biphenyloxycarbonylphenyl methacrylate (BPCPMA) were synthesized by the reaction of p-acryloyloxybenzoyl chloride and p-methacryloyloxybenzoyl chloride with 4-hydroxybiphenyl, respectively, and polymerized by bulk polymerization in vacuum by using dicumyl peroxide. The graft copolymerization of the monomers onto polypropylene were carried out by bulk melt polymerization at 170 • C with various concentration levels of the monomers and the initiator in reaction mixtures. The content of monomers in their graft coproducts increased with monomer-initiator percentage in the reaction medium. The graft coproducts were characterized by several available experimental techniques including differential scanning calorimetry, thermogravimetric analysis, Fourier transform infrared spectroscopy, scanning electron microscopy, and mechanical testing. Moreover, the crucial changes in the mechanical performances pertaining to the polypropylene product were investigated by theoretical computations performed based on the density functional theory (B3LYP) with the standard 6-311++G(d,p) level of theory. According to obtained results, the mechanical properties of the graft coproducts deteriorated significantly with the grafting of the homopolymers due to the damage of the rate-dependent viscoelastic deformation or yielding, leading to enhancement in the surface energy values. At the same time, experimental evidence confirmed that the poly(BPCPA) materials exhibited much weaker secondary Van der Waals bonds than those in the poly(BPCPMA) products.

Detailed analysis on thermal, microstructural, mechanical, and morphological features of side chain liquid crystalline polymer/isotactic polypropylene graft copolymers: Effect of grafted and ungrafted polymer units

“…In addition to that, it is known that the groups presenting in the grafted units affect highly the crucial characteristics of the thermoplastics such as IPP. 10,11 Namely, liquid crystalline polymer (LCPs) with their remarkably rigid, rod-like, and stiff molecular backbone causes to form well-ordered structure and better arrangement with dimensional stability in the polymer matrix by forming highly orientations and alignments. Moreover, the existence of LCPs in the polymer matrix, which gains the ability to show the anisotropic behavior due to the underlying or subunit groups called as mesogens, leads to significant advance in the mechanical performance by means of their comparatively higher load capacity.…”

“…In addition to that, it is known that the groups presenting in the grafted units affect highly the crucial characteristics of the thermoplastics such as IPP 10,11 . Namely, liquid crystalline polymer (LCPs) with their remarkably rigid, rod‐like, and stiff molecular backbone causes to form well‐ordered structure and better arrangement with dimensional stability in the polymer matrix by forming highly orientations and alignments.…”

Role of boron mineral size on thermal, microstructural and mechanical characteristic of IPP

“…The thermograms of virgin IPP and the composites containing varying contents (5, 10, 15, 20 and 30) and sizes (45 and 75 µm) of ulexite were depicted graphically in Figure 1. The endothermic heat flows appearing at both figures was attributed to the melting of IPP crystalline domains [37]. Moreover, the results showed that the crystalline melting temperatures of IPP were highly depended on both the contents and size of the ulexite presenting in the IPP matrix.…”

Investigation of the decomposition behavior of the fluoroalkyl acrylate homopolymer and its grafted copolymers onto high-density polyethylene

“…The I.R. vibrations at ~700 and 840 cm -1 were due to out-of-plane bending vibrations of C-H bonds in vinylic groups [26]. As the temperature increased, the I.R.…”