Dynamic and static mechanical properties of PP/EVA blend nanocomposites: Effects of type of masterbatch preparation technique and nature of compatibilizer

Abstract

Polypropylene (PP)/poly (ethylene-co-vinyl acetate) (EVA) nanocomposites were prepared with use of 3 wt% of organophilic halloysite nanotubes (Org-HNTs) and 3 types of compatibilizers in two steps. First, masterbatchs of EVA and the compatibilizers with the Org-HNT were prepared by two different preparation techniques; melt masterbatch (MM) and solution masterbatch (SM). The masterbatchs were then melt compounded with PP in the second step. Special attention was paid to effects of nature of compatibilizer and masterbatch preparation technique on morphology-mechanical property relationship for the composites. Poly(ethylene-vinyl acetate-carbon monoxide) (EVACO) and maleic anhydride grafted EVA (EVA-g-MA) were used as EVA-based compatibilizers which gave a homogeneous distribution of the nanotubes in the matrix and at the matrix-elastomer interphase as compared to maleic anhydride grafted PP (PP-g-MA). The both masterbatch techniques provided a core-shell morphology composed of nanotubes as core surrounded with elastomer phase as a shell, which led to higher toughness and impact resistance for the composites. Particularly, the EVACO compatibilizer provided the highest toughness, tensile modulus and impact resistance for 3% Org-HNT loaded nanocomposite produced with the SM technique. The same nanocomposite was found to act as an effective damper with an optimum modulus in a broad range of temperature and show a relatively higher creep resistance than the counterpart produced with the MMT technique. It also exhibited 66% higher scratch resistance compared to the PP/EVA blend, which makes it advantageous for the visible parts in automotive applications.

High strength, tough/damping and creep resistant EVA/HNT nanocomposites via help of EVA-g-MA compatibilizer

“…The observed increases in tan δ relative to the pure EVA polymer can be attributed to the friction-induced ability between polymer molecules and nanotubes to convert mechanical energy into heat energy. 12,27,28 It is seen from the Table 3 that the EVA/5H as the binary composite has the lowest damping parameter and storage modulus at room temperature, which is consistent with its tensile mechanical test results (Table 2). This can be ascribed to the HNT aggregates visible in the SEM pictures of the EVA/5H microcomposite structure (Figure S5, Supplementary Material File).…”

“…12 At higher loadings (7 phr), there may be relatively higher intertubular interactions between the nanotubes leading to some regions in the EVA matrix without Org-HNT, that weakens elastic recovery ability. Therefore, EVA/EMA-5H composite can be considered as the material with optimum composition, which has better creep deformation resistance with its high elastic character at short time deformation 28 in accordance with its high dynamic modulus (Table 3).…”

“…Organophilic halloysite nanotube interacting with polymer molecules have been shown to reduce creep deformation by limiting polymer molecular mobility. 28 Although the EVA/ EMA-7H composite had the lowest creep strain, the EVA/ EMA-5H composite with 5 phr Org-HNT had a lower permanent deformation as well as a higher creep rate and recovery percent (Table 4). This can be most probably due to well-distributed nanotubes in the matrix with optimum amount of the Org-HNT (5 phr) resulting in the composite with high elastic character, decreasing the permanent deformation after the stress was removed.…”

Thermal, mechanical, electrical properties of poystyrene/poly (styrene-b-isobutylene-b-styrene/carbon nanotube nanocomposites

“…The information about creep resistance of the material is provided with creep strain and recovery versus time curves. [32][33][34] Short-term isothermal creep behaviors of PS, PS20SIBS blend, and its nanocomposites as well as PS-5CNT as representative binary composite were investigated. The creep test results are presented in Table 5.…”