Effects of poly(butylene adipate‐co‐terephthalate) and ultrafined wollastonite on the physical properties and crystallization of recycled poly(ethylene terephthalate)

Abstract

Recycled poly(ethylene terephthalate) (rPET), obtained mainly from postconsumer bottles, was melt-mixed with either poly(butylene adipate-co-terephthalate) (PBAT) or PBAT plus ultrafine wollastonite (5 lm) at different weight ratios on a twin-screw extruder and then injection-molded. Among the five rPET/PBAT blends (10-50 wt% PBAT) evaluated, the 80/20 wt% rPET/PBAT blend exhibited the highest tensile strength and degree of crystallinity, a slight increase in the tensile strain, and a remarkable increase in the melt flow index, but a lower tensile modulus and thermal stability with respect to the neat rPET. This blend was subsequently filled with four loading levels of wollastonite (10-40 wt%), where the tensile properties (modulus, strain at break, and strength) and thermal stability of the blend were all improved by the addition of wollastonite in a dose-dependent manner. Based on differential scanning calorimetry analysis, the crystallinity of rPET in the rPET/PBAT/wollastonite composites decreased in the presence of wollastonite, accompanied with a noticeable increase in the glass transition, cold crystallization, and crystallization temperatures, but only a slight change in the melting temperature was noted compared with those of the neat 80/20 wt% blend. Moreover, the addition of wollastonite at 30 wt% or higher showed a strong reduction in the melt dripping of the composites during combustion. J. VINYL ADDIT. TECHNOL., 00:000-000, 2015.

Use of synthetic wollastonite nanofibers in enhancing mechanical, thermal, and flammability properties of polyoxymethylene nanocomposites

“…The nature of SWN provides a large contact area with the polymer matrix and enhances the stress transfer. [52] Besides, a good dispersion with a very small agglomeration of SWN in the POM matrix was observed based on the micrographs from FESEM and EDX analysis, which is one of the significant factors that led to the increment in tensile strength when in low SWN content. However, the tensile strength of nanocomposites decreased with increasing SWN content when it surpassed 1 phr and reached the lowest value of F I G U R E 4 Scanning electron micrograph and energy dispersive X-ray analysis mapping of fractured specimens at 1 k magnification for polyoxymethylene nanocomposites with synthetic wollastonite nanofibers content of (A) 0.5 phr, (B) 1.0 phr, (C) 1.5 phr, (D) 2.0 phr, (E) 3.0 phr.…”

Composites of poly(lactic acid)/poly(butylene adipate‐co‐terephthalate) blend with wood fiber and wollastonite: Physical properties, morphology, and biodegradability

“…One of the global concerns at the present days is mainly due to the ecological problems related to the environmental pollution caused by petroleum‐based plastics. The manifold consumption of plastics in industries and households is attributed to their useful properties and relatively easy processing into various articles, which inevitably generate an excessive quantity of discarded plastic waste accumulation in the environment due to their inherent nonbiodegradability and high atmospheric resistance . The entire process that plastics can be metabolized by microorganisms is time consuming, which therefore takes an extremely long time to degrade, giving rise to the serious ecological and economic problems .…”

“…However, some applications of PLA are found to be limited due to its high brittleness and low toughness . PBAT, an aliphatic‐aromatic copolyester with high toughness, flexibility, melt processability, and thermal stability, is a petroleum‐based plastic but fully biodegradable through the metabolism of biological enzymes or microorganisms existing in soil or compost . These suggest PBAT as a good option for melt blending with PLA, which is a straightforward and relatively simple method to improve toughness and application of the PLA‐based product without the expense of reducing its biodegradability .…”

“…Wollastonite (WT), a calcium metasilicate (CaSiO 3 ) mineral, occurs naturally in an acicular (needle shaped) crystal structure with a high aspect ratio (L/D of 10–20). The WT used in the polymer industries has a high chemical purity with a range of useful properties including a high chemical and thermal stability, low coefficient of thermal expansion and water absorption, high level of whiteness and hardness (Moh's hardness 4.8), and small health hazard compared to asbestos as well as low cost . These properties recommend both WF and WT for inclusion into the PLA/PBAT blend matrix to produce composite materials with improved properties and applications.…”

Mechanical properties of wollastonite reinforced thermoplastic composites: A review

“…The work on the effect of different loadings of ultrafine wollastonite on the mechanical properties of the rPET/PBAT blend was documented . The improved tensile properties are tensile modulus (40 wt% optimal), tensile strength (10 wt% optimal) and strain at break (only improved at 10 and 20 wt%).…”