Table 2.

The type of thermoplastic polymer and CF, modification techniques for CF, and mechanical properties of a variety of CFRTP composites.

Composite Material	CF Modification Method	Mechanical Properties	[Reference No.] (Publication Year)
PEI/CCF	Not mentioned	Young’s modulus, toughness, and % strain with respect to the loading direction were increased remarkably.	[15] (2010)
PP/RCF	Coupling agents followed by plasma treatments	An increase of up to 47.8% in ILSS.	[28] (2012)
CBT/CF	Microwave plasma treatments	Tensile strength enhanced by ~436.3%.	[34] (2014)
PP/SCF	Sizing materials followed by plasma treatment. A coupling agent was added to all samples	An increase of up to 47.8% in ILS.	[39] (2014)
PP/LCF	Coupling agent	The mechanical strength of the resulting composite was significantly enhanced.	[40] (2014)
PVDF/CF	Coupling agent	Flexural strength and modulus improved by 47% and 74%, respectively.	[44] (2016)
PA6/CF	Coupling agent and sizing treatment	The tensile strength of composites containing LCF was much higher than other composites having SCF by 24%.	[47] (2014)
PC/CF	Sizing materials	The tensile strength and modulus improved by 150% and 540%, respectively.	[48] (2014)
PPEK/CF	Sizing materials	The value of ILSS of sized CF is about 51.50 MPa, higher than the unsized CF, which was around 39.50 MPa.	[50] (2013)
PPEK/CF	Sizing materials	About 80% of the ILSS in PPEK/CF composite system was attributed to residual radial compressive stress at the fiber/matrix interface.	[51] (2013)
PC/shopped CF	Material coating followed by coupling agent treatment.	The strength and modulus of composites continuously increased along with a clear ductile-brittle transition by increasing the amount of CF.	[52] (2018)
HDPE/CF	Without using any coupling agent	Flexural properties increased significantly upon increasing the layer of CF in the composites.	[54] (2016)
POM/CF	Oxidation treatments	The flexural strength and modulus were enhanced remarkably.	[57] (2015)
PA12/CF	Oxidation method followed by coating with a layer of PA12	The flexural strength and modulus improved by 114% and 243.4%, respectively.	[60] (2011)
UHMWPE/CF	Acid treatment	A 70% increase in ILSS was observed.	[61] (2017)
PA6/ABS/SCF	Acid treatment	The tensile strength and tensile modulus improved significantly. However, these properties were enhanced dramatically when PA6 was blended with ABS.	[62] (2011)
PI/CF	Ozone modification and air-oxidation modification.	Improved friction and wear properties of the composite.	[64] (2010)
PP/RCF	Different plasma powers treatment	The tensile and flexural strength values of composites increased considerably by 17% and 11%, respectively, at 100 W.	[69] 2019
PP/CF	Irradiated PP as compatibilizer agent.	The tensile strength improved by 30%.	[70] (2013)
PP/SCF	Material coating	All flexural, tensile, and impact strength increased by about 43%.	[75] (2018)
PA6/CF	Material coating	ILSS increased by 40.2%.	[77] (2018)
PES/CF	Material coating	The maximum improvement was 12.1%, 31.7%, 12.4%, and 17.3% for the tensile strength, Young’s modulus, flexural strength, and flexural modulus, respectively.	[78] (2015)
PP/CF	Material coating	The ILSS increased by 300%.	[83] (2013)
PEEK/CF	Material coating	An increase of 115.4% and a 27% increase in impact toughness.	[84] (2017)
Nylon/CF	Not mentioned	An increase in ILSS of 33%.	[85] (2019)
ABS/CF	Not mentioned	An enhancement in hardness and compression strength was reported.	[87] (2014)
PPS/CF	Not mentioned	The strength, modulus, wear resistance, and hardness were improved significantly, although the strain values at break and impact strength were slightly decreased.	[88] (2013)
PTFE/CF & PPS/CF	Sizing materials	The strength, modulus, hardness and wear resistance, the elongation at break, and hardness were improved.	[89] (2016)
PTT/CF	Sizing materials	A significant tensile enhancement of up to 120% and flexural strength up to 30% were observed.	[91] (2012)
PA6/CF	Not mentioned	The addition of CF significantly enhanced flexural strength and modulus by 208% and 438%, respectively.	[92] (2014)
PA6/CF	Not mentioned	The results indicated that excellent tensile properties, including tensile modulus and strength and uniform CF distribution, have been proved.	[93] (2018)
PA6/CF	Not mentioned	An increasing CF loading led to improvements in tensile strength, modulus, and hardness, but reduced strain at break values of composites. Meanwhile, the investigated length ranges of CF (0 to 50 µm) had no effect on these mechanical properties except that strain at break was improved.	[98] (2013)
PP/SCF	Sizing materials	Tensile strength, tensile modulus, and impact strength were improved upon the increasing amount of SCF despite reducing fiber length, tensile strength, tensile modulus, and impact strength.	[102] (2020)
PBT/CF	Not mentioned	Improvements in tensile strength up to a certain amount of CF; however, further addition of CF led to a reduction in such property.	[103] (2016)
PI/CF	Not mentioned	The tensile strength was higher than 1200 MPa in the fiber direction on a temperature range varying from −50 to 250 °C but with low ILSS at high temperatures.	[104] (2016)
PEEK/CF	Not mentioned	Improvements in wear resistance were reported.	[105] (2019)
PEEK/CF	Coupling agent	The tensile strength and modulus increased by 455% and 168%, respectively.	[107] (2018)
PA6/CF	Coupling agent	The ultimate tensile strength, elastic modulus, and elongation at break values were exceptional.	[108] (2016)
PK/CF	Not mentioned	An enhancement in Young’s modulus of 520% and in tensile strength by 189%. In contrast, a significant decrease in the elongation at break was observed in the PK/CF composites even at very low loading.	[109] (2019)
PLA/SCF&CCF	Not mentioned	The tensile strength and flexural stress increased by 460% and 121%, respectively.	[113] (2021)
UHMWPE/CF	Not mentioned	Young’s modulus with the tensile strength significantly increased by 415% and 46%, correspondingly. However, the elongation/strain at break decreased substantially by 95%.	[114] (2014)