Preparation Of Epoxy Pickering Emulsions And Application In Basalt Fiber Sizing Agents

As a new resource of green materials,basalt fiber and its reinforced polymers(BFRP)have been widely used in some fields,such as civil construction,war industry and ship industry,because of their high specific strength,high specific modulus and environmental friendliness.But the BFRP showed poor hydrothermal aging,which have become an urgent problem to be solved.According to the surface characteristics of basalt fiber,a cationic surfactant(cetyl trimethyl ammonium chloride,CTAC),a nonionic surfactant(PEO-PPO-PEO block copolymer,F108)and a silane coupling agent(?-glycidoxy propyl trimethoxy silane,KH-560)were introduced to modify the surface of the fumed silica particles respectively.Then the modified silica particles were used to stabilise eco-friendly bisphenol-F epoxy Pickering emulsions to improve hydrothermal aging and green manufacturing.Finally,these Pickering emulsions were applied as the film-former for basalt fiber(BF)sizing agents.In this thesis,the surface peculiarities of the water sized BF were characterized.The results showed that the bare BF surface was polar and negatively charged.Therefore,a small amount of cationic surface modifiers,non-ionic surface modifiers or silane coupling agents were used to modify the fumed silica particles for preparation of bisphenol-F epoxy Pickering emulsions.It was expected that these Pickering emulsions would not only significantly reduce the content of emulsifier which had adverse effects on the environment and interfacial adhesion,but also introduce a large number of nanoparticles onto the BF surface,which would eventually enhance the interface bonding between the fiber and the matrix resin,and improve the hygrothermal aging performance.Both cationic surfactant CTAC and nonionic surfactant F108 could perform the surface wettability and flocculation modification of the fumed silica,and made it become Pickering emulsifiers.When CTAC is 0.004 wt%or F108 is 0.16 wt%,the average particle size of prepared PE cationic and PFE nonionic Pickering emulsions were both small,and showed no stratification during 6 months.And the sizing application tests for PE cationic and PFE nonionic Pickering emulsions were carried out on a basalt fiber production line,respectively.Compared with the control sample of the emulsion prepared by the phase-inversion emulsification method with 4.5wt%of F108,the properties of the basalt fibers and their BFRP sized by the sizing agents of both Pickering emulsion served as the film-former were improved.However,the water absorption of unidirectional basalt fiber reinforced polymers(Uni-BFRP)prepared by PE cationic Pickering emulsion was only reduced by 21.1%.The water absorption of Uni-BFRP and the bending strength of Uni-BFRP after hydrothermal aging treatment prepared by PFE nonionic Pickering emulsion were only reduced by0.9%and 8.8%,respectively.Both PE cationic and PFE nonionic Pickering emulsions failed to meet the three target values of this thesis.In addition,it was found that the emulsifying temperature could not be ignored for the preparation of Pickering emulsion using bisphenol F epoxy resin as oil phase because of its high viscosity.The optimal emulsifying temperature was 60 ~oC,and the saturated content of the fumed silica was 4 wt%.When the silane coupling agent KH-560 was used as the surface modifier for the fumed silica to prepare the epoxy Pickering emulsions,it was found that silane KH-560 could not perform the flocculation modification of the fumed silica for its molecular chain was too short,and the epoxy Pickering emulsion for BF sizing agents could not be prepared by increasing the addition of KH-560.Using F108 or a nonionic lubricant NBR-1090 as the flocculant,it was found that F108 showed a significant synergistic effect with the fumed silica modified by KH-560 to prepare the epoxy Pickering emulsions.When KH-560 and F108 were only 0.06 wt%and0.05 wt%,the average particle size of the prepared PKFE compound Pickering emulsion was the smallest,and no stratification was observed during 6 months.Moreover,the sizing agent prepared by the PKFE compound Pickering emulsion improved the performance of BF and its BFRP completely,and realized the three target values.The water absorption of Uni-BFRP was decreased by 33.7%,the tensile strength of the impregnated BF roving and the bending strength of Uni-BFRP after hydrothermal aging treatment were increased by 67.6%and 19.7%,respectively.To summary,the compound Pickering emulsion prepared by the synergistic effect of the silane coupling agent which can form chemical bonds with fumed silica and the block copolymer with lower water absorption had the best performance.And the compound Pickering emulsion has been applied to the BF trial production of small lot size,and the first article inspection of a novel BFRP storage and launching box has been completed.Pickering emulsion has great prospects as the film-former for fiber sizing agents.