Recent studies on accelerated weathering aging test setup and test conditions of different biocomposites and main finding^a.

Composites	Weathering condition & standard	Irradiation intensity & wavelength	Chamber environment	Test duration	Results	Ref.
WPCBP/WF/PP	UV-340A accelerated weatherometer, ISO 4892-1	0.83	50 °C	15 days	WPCBP and WF enhance the retention rate of mechanical prop. of PP after UV exposure	122
					Higher amount of WPCBP increases the carbonyl index due to the presence of transition metals in WPCBP which accelerate the photo-aging
Linseed cake/PLA	UV light, ISO 4892-3	0.76 W m−2, 340 nm	60 °C	250 and 500 h	Incorporation of biofiller accelerates the degradation	123
					Hydrolytic degradation on amorphous phase (initial UV aging – 250 h)
					Hydrolytic degradation on crystalline phase (later UV aging – 500 h)
SiCO/PLA	Xenon lamp, ASTM G155-13 cycle 1	0.35 W m−2 (340 nm)	63 °C, 30% humidity, light and water spray for 18 min	260 and 520 h	Tensile properties, thermal stability and rheology decreased after aging, while, % crystallinity increased	124
PF/PP, PALF/PP	Mercury pressure lamps	400 watts (300 nm)	60 °C	30, 40, 50 h	PF/PP shows better properties retention than PALF/PP after photo-aging due to higher lignin content of PF	116
Wood fibre/PP (bleached and unbleached) with MAPP	Fluorescent bulb UVA, ASTM G154-00a	0.68 W m−2 (340 nm)	50 °C, 2 h condensation per cycle	150, 400, 600, 800 and 1000 h	Both bleached and unbleached wood fibre composites shows reduction in mechanical prop. After accelerated weathering	56
					Reduction in mechanical prop. was due to degradation of lignin, chain scission of PP and deterioration of fibre–matrix interface
Wood flour/PP with MAPP	Weather-Ohmeter (xenon arc	3500 W lamp, 60 W m−2, 300–400 nm	60 °C	14 days	Recycled of the UV-aged WF/PP were able to recover the initial properties of the WF/PP biocomposites	120
WF/PP, lignin/PP, cellulose/PP	QUV accelerated weathering, ASTM G154	0.89 W m−2, at 340 nm	60 °C, 4 h condensation per cycle	960 h	Composite containing lignin was more sensitive to photodegradation (from color change results)	125
					Lignin/PP showed better retention in flexural strength and modulus, better hydrophobicity and less cracks, on UV-aged surface than PP biocomposites
Starch/WF/PLA with 15% of glycerol	Fluorescent lamps, ASTM G154-06	0.89 W m−2, at 340 nm	4 h condensation per cycle	300, 600 and 1200 h	Carboxylic acid was formed on the surface after UV-aging	126
					Glycerol exhibited stabilize effect on the UV durability of the biocomposites
Lignin/PLA	Mercury lamp	39 mW cm−2, 200–700 nm	30 °C, 60% humidity	600 h	Free surface energy increased after weathering	115
					Lignin/PLA show less reduction in tensile and impact strength than other samples after UV-aging
Mt/PLA (1 mass%)	Fluorescent lamps, SAE J2020, ASTM G154-05 and ISO 4892-3	0.49 W m−2, 310 nm	70 °C, 4 h dark condensation per cycle	50, 100, 150 and 200 h	PLA nanocomposite with 1 mass% Mt clay showed extremely beneficial effect on the durability performance after accelerated weathering (good mechanical prop. retention)	127
HNT/PLA	Fluorescent lamps, cycle-C of the ISO 4892-3	0.49 W m−2, 310 nm	70 °C, 4 h dark condensation per cycle	300 h	Intensities of the distinctive IR bands of PLA were decreased after weathering degradation due to photolysis, hydrolysis and chain scission	128
					Reinforcing effect of HNT in PLA could compensate the loss in mechanical prop. After aging
TiO2/EVA/PLA	Accelerated weathering, ISO 4892/3	NS	60 °C, 8 h irradiation, 4 h humidity condensation per cycle	8–56 cycles	Different TiO2 crystal form could affect the degree of photodegradation	129
					Rutile TiO2 do not enhance the degradation, but anatase and mixed crystals TiO2 nanoparticles promoted the degradation of the nanocomposites
WF/PP with pigments	Accelerated weathering, ASTM G 154	0.89 W m−2, at 340 nm	60 °C, 8 h irradiation, 4 h condensation per cycle	240, 480, 720 and 960 h	Incorporation of pigments was proven to be more effective staining method for improving color stability during weathering as compared to the use of dye WF	130
WF/HDPE	Accelerated weathering, ASTM G154-12a	0.89 W m−2, at 340 nm	60 °C, 8 h irradiation, 4 h condensation per cycle	500, 1000, 1500, and 2000 h	Weathering degradation of the biocomposites is affected by the type of WF	131
					A. Mangium/HDPE shows better surface color and properties stability after aging than E. urophylla and P. caribaea/HDPE
ZnO/WF/HDPE	UVB lamps, ASTM D4329	313 nm	60 °C, 8 h irradiation, 4 h condensation per cycle	500, 1000 and 1500 h	Surface cracks, contact angle changes and mechanical prop. loss were reduced with increasing ZnO content	132
					Incorporation of ZnO changed the photodegradation mechanism of the biocomposites
Teakwood sawdust/PBS	ASTM-G154 cycle A	NS	60 °C, 8 h irradiation, 4 h condensation per cycle	5 cycles, 60 h	Tensile modulus increased while flexural properties decreased	112
					Loss in mechanical prop. was due to the hydrolytic degradation which induced by the hydrophilicity of lignocellulosic biofibre
Biofibres (Oak, cotton burr and guayule bagasse)/HDPE	Accelerated weathering, Fluorescent UV lamps, ASTM G 154	0.85 W m−2, 340 nm	45 °C, UV irradiated for 4 h (60 °C), condensation for 4 h (50 °C)	2200 h	Coupling agents helped to retain the mechanical prop. Of biocomposites after UV exposure	133
					Biofibres accelerates the UV degradation rate of HDPE
Flax fibre/epoxidized sucrose soyate	40 watt UVA-340 fluorescent lamps	0.5 W m−2	40 °C, 4 h UV and water condensation	1000 h each side	The properties of biocomposites reduced after weathering	134
					Fibre treatments aid in improving resistance to property degradation after weathering
FDE/PLA, SD/PLA	UVA-340 fluorescent lamps		60 °C, 8 h UVA radiation, 4 h condensation	0, 250, 500, 750 and 1000 h	Larger extend of mechanical prop. deterioration was observed for FDE/PLA as compared to SD/PLA biocomposites after UV-aging	135

^aAbbreviation: WPCBPs: waste-printed circuit boards; WF: wood flour; SiCO: capsicum oleoresin encapsulated porous silica; PF: palm fibre; PALF: pineapple leaf fibres; MAPP: maleated polypropylene; Mt: montmorillonite; HNT: halloysite nanotubes; EVA: ethylene vinyl acetate copolymer; NS: not stated; PBS: poly(butylene succinate); FDE: farm dairy effluent; SD: wood sander dust.