Featured Publications

DOI

Mechanical and thermal properties of sepiolite strengthened thermoplastic polymer nanocomposites: A comprehensive review

 

Abstract

Sepiolite (Si12Mg8O30(OH,F)4].(H2O)4·8H2O) is a valuable filler with an enormous capacity to be used in thermoplastic composites, substituting costly reinforcing fillers, such as graphene and CNTs. Sepiolite strengthened polymers nanocomposite materials have encouraged the field of research and ventures because of their strengthening ability and bio-compatibility in polymer composites. Sepiolite shows remarkable characteristics over various fillers due to its higher specific surface area and channel type structure. Numerous investigations were performed to decide different properties of Sepiolite strengthened polymer composites in various applications, for example, tensile strength, flexural strength, impact strength, stiffness, thermal, flammability, thermo-mechanical, and morphological. This review paper focuses on the mechanical and thermal properties of sepiolite strengthened polymer nanocomposites. Generally, it can be determined that the properties of sepiolite loaded thermoplastic polymer composites mainly depend on filler content, matrix, bond interaction, shape, size of sepiolite particles. Further assessment and development are required to expand its utilization in several applications. These comprise the utilization of nano-size sepiolite made synthetically as functionalized filler in thermoplastics.

DOI

Mechanical and thermal properties of a newly developed sepiolite filler-filled rPET/PA11 thermoplastic nanocomposites

Abstract

The study examined the impact of sepiolite filler-filled nanocomposites in a novel recycled polyethylene terephthalate (rPET)/polyamide (PA11)/joncryl® blend. Sepiolite filler significantly improved the mechanical and thermal properties of nanocomposites. A twin-screw extruder and injection moulding machines were employed to manufacture five different formulations of nanocomposites. The tensile strength (37.6 MPa) and Young’s modulus (944.25 MPa) of the blend NCS-0 improved with the addition of 2 phr of sepiolite. The tensile strength and Young’s modulus of nanocomposites (NCS-2) were recorded at 41.3 MPa and 974.25 MPa, respectively. The lowest sepiolite filler content (2 phr) had the maximum tensile strength among all other ratios. The flexural strength of NCS-2 was recorded at 47.3 MPa. The tensile and flexural modulus of nanocomposites were significantly enhanced by incorporating 2 phr of sepiolite. The impact strength of NCS-2 (252.98 MPa) was much higher than NCS-8. The addition of sepiolite filler increased the glass transition temperature (Tg) by 38 %. The onset of decomposition temperature (Tonset) of the blend (NCS-0) improved by 20–22° Celsius (oC). Overall, nanocomposites with 2 phr sepiolite demonstrated the ultimate mechanical and thermal properties. These results explored new ways of using rPET/PA11 compatibilized blend in the automotive industry.

DOI

A novel recycled polyethylene terephthalate/polyamide 11 (rPET/PA11) thermoplastic blend

Abstract

This work explores a novel blend of recycled polyethylene terephthalate/polyamide 11 (rPET/PA11). The blend of rPET/PA11 was introduced to enhance the mechanical properties of rPET at various ratios. The work’s main advantage was to utilize rPET in thermoplastic form for various applications. Three different ratios, i.e. 10, 20 and 30 wt.% of PA11 blend samples, were prepared using a twin-screw extruder and injection moulding machine. The mechanical properties were examined in terms of tensile, flexural and impact strength. The tensile strength of rPET was improved more than 50%, while the increase in tensile strain was observed 42.5% with the addition of 20 wt.% of PA11. The improved properties of the blend were also confirmed by the flexural strength of the blends. The flexural strength was increased from 27.9 MPa to 48 MPa with the addition of 30 wt.% PA11. The flexural strain of rPET was found to be 1.1%. However, with the addition of 10, 20 and 30 wt.% of PA11, the flexural strain was noticed as 1.7, 2.1, and 3.9% respectively. The impact strength of rPET/PA11 at 20 wt.% PA11 was upsurged from 110.53 to 147.12 J/m. Scanning electron microscopy analysis revealed a dispersed PA11 domain in a continuous rPET matrix morphology of the blends. This work practical implication would lead to utilization of rPET in automobile, packaging, and various industries.
DOI

Enhanced mechanical properties of a novel compatibilized recycled polyethylene terephthalate/polyamide 11 (rPET/PA11) blends

Abstract

This research investigates various proportions of a compatibilizer, Joncryl®, in a newly developed blend of
rPET/PA11 having 80 wt% rPET and 20 wt% PA11. The proposed blend exhibits unique and outstanding mechanical properties. A few of the significant benefits of carrying out this research work include recycling the highest amount of rPET,
saving natural recourses, and encountering the environmental issues associated with the wastage of polymers. Five different
proportions of Joncryl® (0, 1, 2, 3 and 4 phr) were introduced to the blend of rPET/PA11 through a twin-screw extruder and
injection moulding machine. The blend interface studied by scanning electron microscope (SEM) indicated that Joncryl®
boosted the chain extension. The results of tensile strength, Young’s modulus and flexural strength displayed the boost up
in properties at all proportions; however, the properties at 2 phr of Joncryl® were unique and exclusive. The tensile strength
of blend at 2 phr (Joncryl®) is remarkably increased from 26.8 to 46.24 MPa with a uniquely increased strain% from 3.56
to 196%. Young’s modulus is also significantly improved. The impact strength rose from 147.12 to 667.68 J/m.
DOI

An overview of the recent advances in flame retarded poly(lactic acid)

Abstract

Poly(lactic acid) (PLA) is derived from crops, and has a broad application prospect in electronics and electrical, automotive industries due to its biodegradability and good physical and mechanical properties. However, PLA’s flammability and serious melt dripping cannot meet the requirements of terminal products, thus limiting its application. Over the past decade, much research on flame retardant PLA has emerged. This paper reviews the development of PLA flame retardants in recent years, focusing on phosphorus-based, phosphorus–nitrogen-based, bio-based, nanoparticles, intumescent flame retardants, and their combinations. Besides that, the efficiency of flame retardant and its loading on the thermal and mechanical properties of PLA is also thoroughly reviewed. Finally, the future development of flame-retardant PLA is briefly summarized and prospected.
DOI

Emerging trends in flame retardancy of rigid polyurethane foam and its composites: A review

Abstract

Owing to the superior thermal insulating attributes of rigid polyurethane foam (RPUF) compared to other insulating materials (expanded and extruded polystyrene, mineral wool), it remains the most dominant insulating material and most studied polymer foam. Like other polyurethane foam, RPUF is highly flammable, necessitating the incorporation of flame retardants (FR) during production to lower combustibility, promoting its continuous use as insulation material in construction, transportation, and others. The popular approaches for correcting the high flammability of RPUF are copolymerization and blending (with FR). The second method has proven to be most effective as there are limited trade-offs in RPUF properties. Meanwhile, the high flammability of RPUF is still a significant hindrance in emerging applications (sensors, space travel, and others), and this has continuously inspired research in the flame retardancy of RPUF. In this study, properties, and preparation methods of RPUF are described, factors responsible for the high flammability of PUF are discussed, and flame retardancy of RPUF is thoroughly reviewed. Notably, most FR for RPUF are inorganic nanoparticles, lignin, intumescent FR systems of expandable graphite (EG), ammonium polyphosphate (APP), and hybridized APP or EG with other FR. These could be due to their ease of processing, low cost, and being environmentally benign. Elaborate discussion on RPUF FR mechanisms were also highlighted. Lastly, a summary and future perspectives in fireproofing RPUF are provided, which could inspire the design of new FR for RPUF.
DOI

Effects of ammonium polyphosphate and casein on the properties of poly (lactic acid)

Abstract

In this paper, ammonium polyphosphate (APP) and casein (CSN) were added to poly (lactic acid) (PLA) to improve flame retardancy and maintain biodegradability. The flame retardancy, mechanical, and thermal properties of PLA/APP/CSN composites were evaluated, and the optimum ratio of APP and CSN was determined. The results showed that with the addition of 9 wt% flame retardant (APP:CSN=5:4), the limiting oxygen index (LOI) of the PLA/APP/CSN composite reached 28.3%, and passed the UL-94 V-0 rating at 3 mm, char residue increased at 800°C and smoke emission was also significantly reduced compared to addition of APP without the addition of CSN. Besides that, the cone calorimeter result showed that the peak heat release rate and total heat release of the PLA/APP/CSN-5 composite were 18.2% and 13.3%, respectively, lower than those of pure PLA. The addition of flame retardants inevitably led to a reduction in tensile and flex strength values, but the impact strength was improved.
DOI

Surface and stability analysis of immobilized laccase on poly (ethylene terephthalate) grafted maleic anhydride nanofiber mat

Abstract

The highest laccase activity recovery for laccase immobilized on PET-g-MAH nanofiber mat was 59.17% using covalent bonding, followed by the crosslinking method. The static water contact angle of PET-g-MAH nanofiber mats was reduced from 129 ± 8o to 109 ± 12o. Based on the Wenzel model, the reduction was due to the decrease in surface roughness of the hydrophobic surface. Besides, the immobilized laccase also withstood high temperature up to 60 °C and retained about 29.22% ± 5.06% of its initial activity after 30 days of storage and repeated use.

CONCLUSION

Laccase immobilization on PET-g-MAH nanofiber has good stability (thermal, storage and reusability) and is recommended to be implemented in the industries. © 2021 Society of Chemical Industry (SCI).

DOI

Optimization strategy for laccase immobilization on polyethylene terephthalate grafted with maleic anhydride electrospun nanofiber mat

Abstract

Enzyme immobilization has been known to be one of the methods to improve the stability and reusability of enzyme. In this study, a strategy to optimize laccase immobilization on polyethylene terephthalate grafted with maleic anhydride electrospun nanofiber mat (PET-g-MAH ENM) was developed. The development involves the screening and optimization processes of the crucial factors that influence the immobilization yield such as enzyme concentration, pH values, covalent bonding (CV) time, CV temperature, crosslinking (CL) time, CL temperature and glutaraldehyde concentration using two-level factorial design and Box-Behnken design (BBD), respectively. It was found that laccase concentration, pH values and glutaraldehyde concentration play important role in enhancing the immobilization yield of laccase on PET-g-MAH ENM in the screening process. Subsequently, the optimization result showed at 0.28 mg/ml laccase concentration, pH 3 and 0.45% (v/v) glutaraldehyde concentrations gave the highest immobilization yield at 87.64% which was 81.2% increment from the immobilization yield before optimization. Under the optimum condition, the immobilized laccase was able to oxidize 2, 2-azino-bis 3-ethylbenzothiazoline-6- sulfonic acid (ABTS) in a broad range of pH (pH 3–6) and temperature (20- 70 °C). Meanwhile, the kinetic parameters for Km and Vmax were 1.331 mM and 0.041 mM/min, respectively. It was concluded that the optimization of immobilized laccase on PET-g-MAH ENM enhance the performance of this biocatalyst.

DOI

Alginate Based Sustainable Films and Composites for
Packaging: A Review

Abstract

Alginate is an abundantly hydrophilic polysaccharide as much as 40 % of dry weight and commonly available
in the cell wall of brown seaweed. The thickening, gel-forming and stabilizing properties of alginate makes it
widely used biopolymer with a broader range of application including packaging. The superior valuable feature
of alginate is the capability to yield a stable gel and insoluble polymer when they react through their
carboxylate group with polyvalent metal cation especially Ca2+. Despite a wide range of applications, alginate
has some drawbacks on the water resistivity due to hydrophilic nature, so its modifications with synthetic and
natural polymers are carried out. This review article presents a different type of additives or polymer and their
impact on the functional properties of alginate based composite films with special emphasis on packaging
application.

DOI

Properties enhancement of packaging materials based on gelatin

Abstract

The main disadvantages of plastic materials are that they do not readily break down in the environment and cause harmful effects. For a specific use, biodegradable and/or edible films have been produced to totally replace some typical polymeric packaging materials. Protein and polysaccharides biopolymers have film-forming properties that are useful for food packaging. Gelatin is an example of a protein that has the ability to form a film, has strong functional qualities, and can be used as an exterior barrier to prevent drying. Gelatin has adverse effects on food packaging application, especially mechanical properties and water vapor permeability. The effect of the incorporation of plasticizers in gelatin films is reviewed and presented. The plasticizer can improve the extensibility, dispensability, flexibility, elasticity, and rigidity of biopolymers and biopolymers composites. The plasticizers reviewed are glycerol, sorbitol, lignin, root essential oils, bergamot oil, lemongrass oil, sucrose, oleic acid, malic acid, and citric acid, and others. These plasticizers have strengthened the film structure by continuity of polymer matrix where the gelatin films become more stretchable and also flexible. This study also discussed the effect of plasticizers on other properties of gelatin film such as water vapor permeability (WVP), thermal properties, water-solubility, moisture content, oxygen permeability, light transmission, and transparency.

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