Studies On The Interpenetrating Polymer Networks Based On CO-PU/HCAA

A kind of prepolymer(CO-PU)were synthesized by 2,4-toluene diisocyanate(TDI) reacted with castor oil(CO)with steping polymerizing method in this paper.Then the new castor oil polyurethane interpenetrating polymer(IPN)were made by CO-PU mixed with 2-hydroxyl-3-chlorop ropyl acrylate(HCAA),benzoperoxide(BPO)as initiator and dibutyl tin laurate(DBTDL)as catalyst at room temperature.The effect of reaction conditions on synthesis of CO-PU were studied by testing the free TDI and-NCO;the effect of the system composition on the mechanical properties of IPN were studied by testing tensile strength;the structure and heat resistant of IPN were studied by using thermal analysis(DSC,TG).The results showed:the remaining -NCO and TDI content of CO-PU increased gradually with increasing temperature,the remaining -NCO and TDI content of CO-PU decreased with increasing the reatio of NCO/OH;the remaining -NCO content of CO-PU decreased with time;the remaining -NCO content of CO-PU decreased obviously after adding catalyst DBTDL.The castor oil polyurethane prepolymer CO-PU was mixed with HCAA,and formed IPN at room temperature;the tensile strength of IPN was gradually increased with curing time increaseing,with the maximum about 22.06MPa at 8th day.The tensile strength of CO-PU IPN increased at first and then decreased with increasing the double bond mole ratio of CO-PU and HCAA,with the maximum at 6:1,and NCO/OH mole ratio nNCO/nOH in CO-PU with the maximum at 2.5;the CO-PI/HCAA had the maximum tensile strength at the content of initiator BPO equal to 0.5%and catalyst DBTDL equal to 0.2%.The special absorption peak of-NCO at 2265cm^-1was disappeared after CO-PU/HCAA formed.The results of TG and DSC revealed that IPN's thermal decomposition divided into three stages,the first was degeneration of the polyurethane network which lose weight was 33.09%from 220℃to 328℃,the second was degeneration of the polyurethane network that lose weight was 53.32%from 328℃to 440℃,the last was the melting of the segment that lose weight was 8.69%from 440℃to 500℃;The heat resistance was different about the system composition.The CO-PU/HCAA has the maxâ–³H and the best heat resistance when nCO-PU/nHCAA was 6:1.The CO-PU-2.5/HCAA has best heat resistance.The degeneration of the polyurethane network formed CO₂,H₂O and isocyanate,alcohol,et al.The degeneration of the polyolefine network formed major olefin and hydrocarbon of methane series.The degeneration of CO-PU/HCAA was one-order reaction,the activation energe respectively was different with different system compositon.The Ea was 52.88kJ/mol,59.42 kJ/mol and 53.53kJ/mol when nCO-PU/nHCAA was 4:1,6:1 and 7:1;The Ea was similar when nNCO/nOH was 2.0,2.5 and 3.0.