بررسی اثر کوپلیمر شانه­ای پلی(وینیل‌کلرید)-پیوند- پلی(بوتیل‌آکریلات) به‌عنوان نرم­کننده بر عملکرد فیلم­های پلی(وینیل‌کلرید)

Research subject: This study investigates the effect of poly(butyl acrylate) (PBA)-based polymeric plasticizers on the performance of poly(vinyl chloride) (PVC) films. The main objectives were the synthesis and evaluation of graft copolymer plasticizers, PVC-g-PBA, with varying PBA chain lengths, and the examination of their impact on the microstructure, mechanical properties, and stability of PVC films.
Research approach: PBA chains with different molar percentages (40–80%) were grafted onto PVC chains via atom transfer radical polymerization (ATRP). The microstructures of the synthesized copolymers were confirmed using Fourier-transform infrared spectroscopy (FT-IR) and proton nuclear magnetic resonance (¹H-NMR). These copolymers were then used as plasticizers (at 22 wt%) in the preparation of PVC films. The mechanical properties (tensile strength and elongation at break), morphology (via wide-angle X-ray diffraction (WAXD)), plasticizer stability in the PVC matrix (extraction test), and thermomechanical behavior (via dynamic mechanical thermal analysis (DMTA)) were evaluated.
Main results: Increasing the molar percentage of PBA in the copolymers reduced the yield stress from 53 to 10 MPa, while significantly increasing the elongation at break from 9% to 162%, indicating enhanced flexibility of the PVC films. WAXD results revealed that at lower PBA contents (up to 63%), chain ordering improved, whereas higher PBA incorporation (73%) led to a notable reduction in crystallinity due to the amorphous nature of PBA. The extraction test confirmed the high stability of the synthesized plasticizers in the PVC matrix after 24 hours. DMTA analysis indicated shifts in the glass transition temperature between phases as the PBA content increased. Compared to the conventional plasticizer dioctyl phthalate (DOP), the synthesized plasticizers exhibited superior mechanical performance and are proposed as a highly stable alternative for PVC applications.