Polyhydroxybutyrate: a review of experimental and simulation studies of the effect of fillers on crystallinity and mechanical properties

Abstract

Polyhydroxybutyrate (PHB) is a sustainable polymer that is a promising candidate for replacing petroleum-based plastics in food packaging. Fillers are used to improve the mechanical properties of PHB composites, simultaneously changing the crystallinity of the polymer matrix. However, it is not well understood how fillers affect crystallisation and microstructure, and thus the resulting mechanical properties of the composite. This review summarises simulation work on polymer nucleation and crystallisation and how nucleation is influenced by different types of polymer-filler interfaces. Experimental studies of PHB composites with a wide variety of fillers are reviewed to find trends between the filler type, crystallinity and mechanical properties. It is clear that fillers act as nucleants that increase the number of spherulites while reducing spherulite size. This behaviour is apparent for almost all fillers regardless of filler chemistry or topology. However, the data obtained from the literature do not seem to produce strong conclusions about the effect of the degree of crystallinity on the tensile properties of PHB-filler composites, although there are some weak trends that indicate the importance of microstructure. In order to enable prediction and control of PHB composite properties, further systematic studies are required to elucidate the effect of specific filler types and the connection between crystallinity, microstructure and mechanical properties.

Magnetoactive Composite Conduits Based on Poly(3-hydroxybutyrate) and Magnetite Nanoparticles for Repair of Peripheral Nerve Injury

“…The total porosity of the scaffolds was computed by the gravimetric method reported previously . Wall thickness values of the conduits were measured by means of ImageJ in optical photographs of the conduits’ cross sections, and the total porosity was calculated using eq normalp orosity 0.25em ( % ) = ( 1 − a pparent density 0.25em ( g cm − 3 ) b ulk density 0.25em ( g cm − 3 ) ) · 100 % The apparent density of the conduits was calculated as follows normala pparent density false( g cm − 3 false) = ( c onduit mass false( normalg false) w all thickness false( cm false) · w all area 0.25em ( cm 2 ) ) The bulk density of pure PHB was assumed to be 1.2 g cm –3 (ref ), while the bulk density of the PHB/Fe 3 O 4 –CA composite (ρ) was calculated using eq ρ = ( m PHB + m magnetite ) / ( m PHB ρ PHB + m magnetite ρ magnetite ) ...…”

“…The total porosity of the scaffolds was computed by the gravimetric method reported previously . Wall thickness values of the conduits were measured by means of ImageJ in optical photographs of the conduits’ cross sections, and the total porosity was calculated using eq The apparent density of the conduits was calculated as follows The bulk density of pure PHB was assumed to be 1.2 g cm –3 (ref ), while the bulk density of the PHB/Fe 3 O 4 –CA composite (ρ) was calculated using eq where m magnetite is the weight of Fe 3 O 4 –CA added to the conduits, m PHB is the weight of PHB in the conduits, ρ PHB is the bulk density of PHB, and ρ magnetite is the bulk density of magnetite (5.1 g cm –3 ).…”

Special Issue: Enabling Research in Smart Sustainable Plastic Packaging

“…However, it is not well understood how fillers affect polymer crystallisation and microstructure, and thus the resulting mechanical properties of the composite. Johnston and co‐workers review a combination of computational and experimental studies examining polymer nucleation and crystallisation, and how nucleation is influenced by different types of polymer–filler interface 14 . The data obtained from the literature do not seem to produce strong conclusions about the effect of the degree of crystallinity on the tensile properties of PHB–filler composites, although there are some weak trends that indicate the importance of microstructure, highlighting the necessity for further systematic studies to elucidate the effect of specific filler types and the connection between crystallinity, microstructure and mechanical properties.…”

Biobased Itaconate Polyester Thermoset with Tunable Mechanical Properties

“…In response, synthetic biobased polymers like polylactic acid (PLA), polycaprolactone (PCL), polyhydroxyalkanoate (PHA), and polybutylene succinate (PBS) offer better control of properties and reproducibility. However, their intricate synthesis involving toxic solvents or catalysts and the need for fillers to tune properties hamper eco-friendly adoption. − Researchers address this by exploring biobased polyols and polyacids to create more sustainable polyesters like poly­(glycerol- co -sebacate) (PGS), poly­(1,8-octanediol- co -citric acid) (POC), and poly­(1,8-octanediol- co -1,12-dodecanedioate- co -citrate) (PODDC), through solventless, catalyst-free polyesterification. These polyesters offer a simple tunability approach by varying monomer molar ratios, driving sustainable innovations across diverse applications, spanning elastomers, − biomedical, − coating, shape-memory polymer, and additive manufacturing. , …”