Rheology, crystallization, and enhanced mechanical properties of uniaxially oriented ethylene–octene copolymer/polyolefin elastomer blends

A Polyolefin Elastomer Encapsulant Modified by an Ethylene-Propylene-Diene Terpolymer for Photovoltaic Applications

In this study, a newly designed adhesion promoter, a modified ethylene-propylene-diene terpolymer (m-EPDM), was constructed via a simple thiol-ene click reaction between the ethylene-propylene-diene terpolymer (EPDM) and 3-mercaptopropyltrimethoxysilane (MPTS) to employ polyolefin elastomer (POE) encapsulants in photovoltaic modules. The grafting reaction of MPTS on an EPDM backbone (thiol-ene click reaction) was verified using 1H NMR, 29Si NMR, and SEM/EDX. The thermal and mechanical characteristics of the POE compounds did not significantly change with an increasing m-EPDM content irrespective of the cross-linking state. Interestingly, the adhesion strength to the glass substrate increased linearly with an increasing m-EPDM content until 9 phr. Also, the POE compounds containing more than 12 phr m-EPDM showed cohesion failure of the encapsulant layer, remaining as a residue of the encapsulant layer on the glass surface after peel testing. The damp-heat test was conducted to evaluate the long-term durability of the photovoltaic module encapsulated with m-EPDM, and no significant power loss was found even after 1000 h under the test conditions.

Investigation of the Effect of Hybrid Nanofiller on the Mechanical Performance and Surface Properties of Bio-Based Polylactic Acid/Polyolefin Elastomer (PLA/POE) Blend

Polylactic acid has stood out among bio-based polymers for its usage in the food packaging industry and biomedical fields. Through the melt mixing process, the toughened poly(lactic) acid (PLA) was prepared with polyolefin elastomer (POE), incorporated via various ratios of nanoclay and a fixed amount of nanosilver particles (AgNPs). The correlation between the compatibility and morphology, mechanical properties, and surface roughness of samples with nanoclay was studied. The calculated surface tension and melt rheology confirmed the interfacial interaction demonstrated by droplet size, impact strength, and elongation at break. Each blend sample exhibited matrix-dispersed droplets, and the size of POE droplets steadily dropped with increasing nanoclay content, corresponding to the enhanced thermodynamic affinity between PLA and POE. Scanning electron microscopy (SEM) acknowledged that the inclusion of nanoclay in the PLA/POE blend ameliorated the mechanical performance by preferable localization in the interface of used components. The optimum value of elongation at break was acquired at about 32.44%, where the incorporation of 1 wt.% nanoclay led, respectively, to 171.4% and 24% enhancement rather than the PLA/POE blend with the composition of 80/20 and the virgin PLA. Similarly, the impact strength reached 3.46 ± 0.18 kJ m^-1 as the highest obtained amount, showing the proximity of 23% progress to the unfilled PLA/POE blend. Surface analysis indicated that adding nanoclay caused the augment of surface roughness from 23.78 ± 5.80 µm in the unfilled PLA/POE blend to 57.65 ± 18.2 µm in PLA/POE contained 3 wt.% nanoclay. Rheological measurements implied that organoclay resulted in the strengthening of melt viscosity as well as the rheological parameters such as storage modulus and loss modulus. Han plot further showed that the storage modulus is always higher than the loss modulus in all prepared PLA/POE nanocomposite samples, corresponding to the restriction of polymer chains mobility induced by the formation of strong molecular interaction between nanofillers and polymer chains.

Construction and Characterization of Polyolefin Elastomer Blends with Chemically Modified Hydrocarbon Resin as a Photovoltaic Module Encapsulant

In this study, polyolefin elastomer (POE) was blended with a chemically modified hydrocarbon resin (m-HCR), which was modified through a simple radical grafting reaction using γ-methacryloxypropyl trimethoxy silane (MTS) as an adhesion promotor to the glass surface, to design an adhesion-enhanced polyolefin encapsulant material for photovoltaic modules. Its chemical modification was confirmed by 1H and 29Si NMR and FT-IR. Interestingly, the POE blends with the m-HCR showed that the melting peak temperature (Tm) was not changed. However, Tm shifted to lower values with increasing m-HCR content after crosslinking. Additionally, the mechanical properties did not significantly differ with increasing m-HCR content. Meanwhile, with increasing m-HCR content in the POE blend, the peel strength increased linearly without sacrificing their transmittance. The test photovoltaic modules comprising the crosslinked POE blend encapsulants showed little difference in the electrical performance after manufacturing. After 1000 h of damp-heat exposure, no significant power loss was observed.