Table 1.

Water-assisted (WA) melt compounding of commodity thermoplastics.

Polymer	Filler Type, Amount	Surfactant Type, Amount	Compatibilizer, toughener type, amount	Compounding	Results	Ref.
LDPE granule/powder	Microcrystalline cellulose 0–30 wt%	-	-	Water injected in the high-pressure compression zone (~125 bar) of a corotating twin-screw extruder.	Cellulose could not be fibrillated in nanoscale. WA contributed to a better dispersion of cellulose compared to the reference “dry” process.	[32]
LDPE LLDPE	Na-MMT 0–5 wt%	Various quaternary ammonium salts	LDPE-g-MA 0–10 wt%	Water, clay slurry, or aqueous surfactant were injected in the high pressure zone of an intermeshing twin-screw extruder (Figure 5).	Design of experiments used to determine effects of surfactants (type, amount) clay amount and processing conditions on mechanical, rheological and barrier properties.	[30,33]
PP 70, 100 part	Na-MMT 0, 5, 10 part	Octadecyl trimethyl ammonium chloride 0, 0.25, 1 part	PP-g-MA 0, 30 part	Corotating intermeshing extruder of very high length-to-diameter ratio (L/D = 77) and special screw design and sealings against high pressure used. Clay slurry injected.	PP/clay nanocomposite by WA melt compounding exhibited similar properties as the reference PP/organoclay. Polymeric compatibilizer (PP-g-MA) required to support MMT exfoliation.	[34]
PP PP-g-MA	Na-MMT, organoclay 21 wt%	-	-	Water injected (amount varied) in the high-pressure compression zone of a corotating twin-screw extruder. PP/(organo)clay masterbatches (MB) also processed by WA technique.	Morphological, mechanical, rheological and thermal properties of the nanocomposites studied. The MB process outperformed the “one pot” version. Water improved the dispersion of clay and proved beneficial to support the chemical reaction between PP-g-MA and hydroxyl groups of the organoclay surfactant.	[35]
PP	Na-MMT, organoclay <7 wt%	-	PP-g-MA (9–10 wt%), Na-acetate (0, 4 wt%) (to convert PP-g-MA into an ionomer)	Water injected in the high-pressure compression zone of a corotating twin-screw extruder.	Morphological, mechanical, rheological and thermal properties assessed. In situ synthesis of “carboxylate clay” from pristine clay and PP-g-MA ionomer, through trihydrate sodium acetate addition with help of WA compounding proved to be an effective alternative to using organomodified clays and compatibilizers.	[36]
TPV (PP-based)	CNF aqueous dispersion (15 g/L) 5 phr	-	EPDM	Crumb EPDM was spray-coated by CNF and melt mixed with TPV.	Morphology, dynamic-mechanical, thermal and tribological properties determined. The fragmented CNF was located in the PP phase.	[37]
TPV (PP-based)	BA (particle size in water 300 nm) 5 wt%	-	-	BA added dry or via WA technique using a corotating twin-screw extruder.	Tensile, thermal, DMA, creep and stress relaxation tests performed. BA located in the PP-phase. WA produced better dispersion than the traditional dry dosage. The better dispersion was best reflected in the creep and stress relaxation results.	[38]
PS	Na-fluorohectorite 0–7 wt%	-	-	Micro- and nanocomposites produced batchwise in a kneader. For nanocomposite preparation Na-fluorohectorite was mixed first with a PS latex which after drying was used as a MB for dilution with molten PS. Dry melt mixing, resulted in microcomposite.	Nanocomposites outperformed the microcomposites with respect to stiffness and resistance to creep. Dispersion in nanoscale affected, however, mostly the initial creep compliance.	[39,40]
PS	BA (particle size in water 25 and 220 nm, respectively) 4.5 wt%	-	-	Nanocomposites produced batchwise in a kneader; dry or through WA technique (latex-mediated). In the latter case PS latex was compounded with BA followed by drying and dilution with molten PS.	Latex-mediated nanocomposites exhibited higher stiffness, resistance to creep, to thermal deflection than the reference composite produced by traditional “dry” melt compounding.	[41]
PS	BA (particle size in water 25 and 220 nm, respectively) 3 wt%	-	SBR from latex 10 wt%	Binary (PS/BA, PS/SBR) and ternary systems (PS/BA/SBR) were produced via WA in a twin-screw extruder	Morphology, DMA, tensile mechanical, impact and short term creep and stress relaxation behaviors studied. BA acted as efficient nanoreinforcement while SBR as toughening agent in the binary systems. BA was mostly embedded in the SBR phase in the ternary blends. Modifiers’ effects best manifested in tensile and stress relaxation tests.	[42]