Study On Aging Resistance Of Polypropylene Carbonate Type Polyurethane

Polypropylene carbonate polyol?PPC?derived from CO₂ and propylene oxide is a kind of green polymer material with industrial application value.After years of efforts,our research team successfully synthesized PPC with high carbonate group content,low by-product and residual catalyst content,and excellent performance.The synthesized PPC polyol has been successfully applied in various industrial production.Until now,the degradation of PPC was mainly focused on the biodegradation of PPC.The researches on the degradation and stability of PPC in natural environment were rarely reported.In this paper,the degradation and aging mechanism of PPC under the circumstance of heat,thermal oxygen and UV light were studied.The changes of viscosity,molecular weight and molecular structure of PPC which was exposed to long-term high temperature with and without oxygen,and UV light were investigated,respectively.Degradation mechanism of PPC under thermal,thermal oxygen and UV conditions was proposed.Moreover,PUD was prepared by using PPC as raw material,and the UV aging resistance of PPC-PUD was researched.The effects of the type,amount and compounding of organic additives on the photoaging resistance of PPC based polyurethane were studied.The research results indicates:?1?PPC showed excellent long-term thermal stability at 120-180?without oxygen.No obvious thermal degradation occurred.?2?At 200-210?,PPC began to degrade with increasing temperature,accompanied by decrease of PPC viscosity and-COO content with time.PC content increased.When the temperature was raised over 220?,random chain scission degradation and zipper degradation appeared.?3?With the existence of oxygen,the tertiary carbon bonded to the ether atom in PPC was oxidatively decomposed to ketone and hydroxyl group at 120-180?,which resulted in the decrease of the molecular weight.At 200-210?,oxidative degradation and zipper degradation occurred.At 220-230?,random chain scission degradation,zipper degradation and oxidative degradation appeared.?4?Antioxidants could effectively inhibit random chain breakage,zipper degradation,and oxidative degradation of PPC.?5?Obvious photooxidative degradation and zipper degradation was detected after7d exposure to the UV light.?6?Compared to the PUDs using PBA,PCDL,PPG and PTMG as soft segments,respectively,PPC based PUD showed better UV resistance than PPG and PTMG type,but lower UV resistance than PCDL and PBA type.?7?The PUD with higher hard segment content showed better UV resistance.?8?The ultraviolet absorbing agent UV-1130 and antioxidant 1010 exhibited excellent UV resistance.With further increasing the additives amount,the UV resistance of UV-1130 increased slightly.However,the anti-ultraviolet effect of 1010 enhanced extremely.To further increase the UV resistance,UV-absorbing agent UV-1130 was combined with the free radical scavenger 1010.At the ratio of 1:3,PPC-type PUD exhibited superior anti-ultraviolet degradation property.After 5d UV irradiation,the strength was almost invariable.