Preparation Of Cationic Nanoparticles With Core-shell Structre For Sugarcane Fibre Hydrophobic Modification

Cationic polymer latex,poly(styrene/butyl acrylate-co-glycidyl methacrylate)[P(St/BA-co-GMA)],which had core-shell structure,was synthesized by a two-step semi-batch emulsion polymerization technology with cetyl trimethyl ammonium chloride(CTAC)as surfactant,ethylene glycol dimethacrylate(EGDMA)as crosslinker,2,2'-azobis(2-methylpropionamidine)dihydrochloride(AIBA)as cationic initiator.The core-shell structure of latex particles was confirmed by the TEM image and the DLS analysis.The influences of the monomer ratio,the surfactant dosage,the initiator dosage,reaction temperature and time on the properties of latex were investigated.The monomer conversion of cationic latex reached to 98.03%when the reaction proceeded under the following conditions:surfactant dosage of 6%,initiator dosage of 0.5%,and 2 h reaction time at 80 ?.The mean particle size and Zeta potential of the resulted latex particles were 57.21 nm and +47.62 mV,respectively.The latex was used for hydrophobic modification of sugarcane fibres.The influences of adsorption time,the latex concentration,pH,temperature and ionic strength on the adsorption of cationic latex on sugarcane fibres were explored.Furthermore,the adsorption kinetics and thermodynamics were also studied.The fitting results suggested that the adsorption of latex on fibres was better described by Pseudo-second-model,and the adsorption rate was dominated by chemical adsorption.The data obtained from adsorption experimental fitted the Langmuir adsorption model well,which means the adsorption was monolayer sorption and the maximum theoretical adsorption capacity of the latex particles on the sugarcane fibres reached 197.6 mg/g.The positive value of AS0 and ?H°,and the negative value of AG° indicated that the adsorption of latex particles onto the surface of sugarcane fibres was spontaneously and the adsorption process was endothermic as well.The SEM,BET,TGA and FT-IR analysis were employed to further confirm the adsorption of latex on sugarcane fibre surface.The water contact angle of the modified fibre was increased from 0 °to 98 °,compared with the untreated fibre,which indicated that the sugarcane fibres were rendered hydrophobic by the latex.According to "similar compatibility" principle,the hydrophobically modified fibres were used as a reinforcing filler to prepare sugarcane fibre reinforced PVC composites.Composite mechanical properties test results showed that the tensile strength,breaking elongation and compression strength of composites were higher than PVC without addition of fibres when modified fibres added into PVC was of 10%.