The Compatibility Study Of Polyurethane/silicone Rubber System And Preparation Of Blending Materials With Polymerization-induced Phase Separation

Thermoplastic polyurethane/silicone rubber(TPU/Si R)blends have the advantages of excellent human touch and biocompatibility,and are widely used in flexible wearable materials,electronic device materials,biomedical materials and other fields.The development of TPU/Si R blends with fine phase structure is of great significance for the preparation of high-performance TPU/Si R materials.However,the compatibility of the TPU/Si R blends is very poor because of the large polarity difference,the application of compatibilizer can optimize the phase of TPU/Si R blends and increase the bonding force between the two phases,which is an important method for preparing TPU/Si R materials with the fine phase structure.At the same time,as a method to control the phase state of blends only through a controllable chemical reaction process,polymerization-induced phase separation(PIPS)has the advantages of simple and controllable preparation process,and no need for solvents and other fillers.This method also can be applied to prepare blends with highprecision phase structure.Therefore,compatibilizer and PIPS were used to regulate the phase state of TPU/Si R system and prepare TPU/Si R blends with excellent performance in this article.Polyurethane-polysiloxane copolymer(PU-PDMS)is an effective compatibilizer for industrial applications,its structure is a key factor affecting the phase structure and interface properties of the blend,but the relationship between its molecular structure and the compatibility effect is still unknown.In the second chapter of this paper,a silane-modified polyurethane(PU-PDMS)of the relative low molecular weight with PTMG(poly-tetrahydro capped with hydroxyl group)and PDMS(Polydimethylsiloxanes capped with hydroxyl group)segments as the mixed soft segment was prepared,and the structure of PU-PDMS was adjusted by the mole ratio of PTMG and PDMS.When the PDMS content in the PU-PDMS is 80%(PU-PDMS-80%),the compatibility effect is best.Under the content of 10 wt.%,compared with TPU/Si R(7/3 wt/wt)blend,the elongation at break of TPU/Si R/PU-PDMS-80% is increased by 57%,and the tensile strength,Si R dispersed phase size and interface thickness of TPU/Si R/PU-PDMS-80% are 2.7,1/6 and 2.3 times that of TPU/Si R,respectively.PU-PDMS compatibilizer can effectively enhance the interface bonding force of TPU/Si R,optimize the phase structure,and improve the performance of the blends,at the same time,by regulating the structure of PUPDMS,the compatibility mechanism of PU-PDMS on TPU/Si R system is proposed,which provides ideas for the design of compatibilizers for other incompatible systems.In the third chapter of this paper,after determining the optimal PDMS content in PU-PDMS,the polyurethane-polysiloxane copolymer compatibilizer with different-NHCOO-content(PU-PDMS-A-X)was prepared,applying PTMG of different molecular weights(Mn=1000,2000,3000 g/mol)to adjust the content of-NHCOO-in PU-PDMS compatibilizers.With the increase of-NHCOO-content,the size of Si R dispersed phase in TPU/Si R/PU-PDMS-A-X decreases and the phase structure is more uniform,among which,PU-PDMSA-H has the best compatibility effect,and the Si R dispersed phase size decreases to 9.5 μm at 10 wt.% content,which is 1/6 of pure TPU/Si R;the tensile strength and elongation at break of TPU/Si R/PU-PDMS-A-H are increased by 173% and 57%,respectively.At the same time,compared with the existing commercial compatibilizer(TPSi U),the Si R dispersed phase in the TPU/Si R/PU-PDMS-A-X blend has finer size and more uniform phase,indicating that the prepared PU-PDMS-A-X compatibilizer has a good compatibility effect.In the fourth chapter of this paper,elastomer materials with similar structures to silicone rubber/polyurethane thermoplastic vulcanizates are prepared by polymerization-induced phase separation(PIPS)to meet the application of related fields.By introducing the principle of PIPS into the preparation of TPU/Si R blending materials,the preparation process is simplified and the structure is easy to adjust,which provides an innovative and feasible solution for the industrial preparation of TPU/Si R composites.According to the results of the structure,phase,mechanical properties and thermal stability of the PIPS-TPU/VI-PDMS system,the feasibility of PIPS for the preparation of TPU/Si R blends was proved,and the optimal phase separation time point of the system was determined.Under the optimal phase separation time point,the size of the crosslinked Vi-PDMS as dispersed phases in the material is 0.54 μm,and the tensile strength and elongation at break of the PIPS-TPU/Vi-PDMS system reach 13 MPa and 450%,the permanent deformation and hysteresis loss are 16.1% and 48.6%,respectively,which are better than the mechanical properties of other materials prepared under other reaction times.It provides an innovative and feasible solution for the industrial preparation of TPU/Si R composites.