Undergraduate: Congcai Wang Supervisor: Professor Ruiwei Guo

1. Department of Polymer Science and Engineering, School of Chemical Engineering and Technology, Tianjin University. Copolymerization reactivity of monomers and sequence structure of copolymers during the curing of UPR Undergraduate: Congcai Wang Supervisor: Professor Ruiwei Guo 2012.9.7

2. 3 3 Content Fountain of the project 1 2 Degradation methods 3 Determination methods Experimental program 4

3. 1. Fountain of the project On basis of developing knowledge on the radical curing of polyester resin systems for AkzoNobel Corporate, the studying team of professor Guo cooperated with AkzoNobel and proposed a project feasibility study report about the research ideas, in which the project was divided into two sub-projects and corresponding research contents.

4. Network structure’s forming and its shielding effect will have an influence on the curing of UPR, and strongly affect properties of UPR, such as toughness, intensity, hardness, shrinkage, etc. Degradation Cured UPR Degradation products 1H NMR 13C NMR DSC FTIR Sequence structure UP/St My task

5. My project: Copolymerization reactivity of monomers and sequence structure of copolymers during the curing of UPR The research content: 2-1. De-crosslinking of cured UPR by alcoholysis or hydrolysis to obtain linear copolymers consisted of fumarate (or maleate) and styrene units; 2-2. Analysis of sequence structure of obtained linear copolymers; 2-3. Study the effect of conversions, monomer content and curing temperature to the sequence structure of styrene units.

6. 2. Degradation methods • Degradation methods of UPR reported are alcoholysis, hydrolysis and Subcritical water. • The degradation of copolymers is a process of opening the ester bonds so that we can obtain short chains or linear chains which are easy to measure. So we also look up other esters’ degradation methods.

7. 2.1 Degradation methods of UPR Alcoholysis: Degradation behavior of unsaturated polyester resin in alcohols.Hojo,H, K. Ogasawara, W. L. Chang, K. Tsuda.Composite Materials.Vol..3,No.4,341-353(1994). The immersion test was conducted by immersing the test specimens in the environmental liquid(pure water, methanol, ethanol, 1-propanol, 1-butanol and methanol solution) at constant concentration and temperature for a maximum of 1600h. Figure 4: After the change in wet weight reaches the maximum(about 12%) independently of temperature it decreases, implying that corrosion is in progress.

8. Methanol Figure 6: The degree of corrosion is in the order methanol＞ethanol ＞ 1-propanol ＞ 1-butanol, which implies that the larger the number of carbon atoms in the alcohol, the larger the molecular size, thus functioning as resistance to diffusion of the alcohol in the resin. Physical degradation is dominant for resin and the degree of corrosion is relatively low. The form of corrosion is of the “penetration type” and the resulting corrosion degradation is due to the transesterification reaction.

9. Alkali hydrolysis by KOH: Crosslinking and Degradation of a Side-Chain-Unsaturated Polyester. N.A.Ghanem,M.H.Nosseir,(Miss)N.I.Hussein. European Polymer Journal,Vol. 7, 943-951(1971). Benzene layer Initiator 1. Extraction Cured UPR UP/St 2. 1M KOH in methanol The bands at 3400cm-1 characteristic for the hydroxyl group is in direct correlation with the experimental hydroxyl values. Distill IR VPO Molecular weight Degradation products Acid and hydroxyl values Calculation Average sequence length

10. n=11 m=0-11 The allylic double bond in the polyester has low reactivity towards styrene which forms branches on the allyl ether side chains. It has higher reactivity towards methyl Methacrylate and its 1:1 mixture with styrene to form real crosslinks between the allyl ether side chains of the polyester.

11. PET(Sulfuric Acid, Nitric Acid, KOH, NaOH.) • Crosslinkable copolyesters(NaOH) 2.2 Degradation methods of other esters Hydrolysis • Alcoholysis

12. 3. Determination methods There are many techniques measuring the sequence structure. The techniques used in UPR mainly contain DSC, FTIR, 1H NMR, 13C NMR. DSC and FTIR can measure conversion rate, and the specras of 1H NMR, 13C NMR can measure the content of less than triad and multi-unit in copolymers. They are also used to calculate the average sequence length.

13. 3.1 DSC, FTIR Effects of Resin Chemistry on Redox Polymerization of Unsaturated Polyester Resins.HUAN YANG, L. JAMES LEE.Journal of Applied Polymer Science, Vol. 84, 211–227 (2002). The reaction kinetics of a series of well-defined polyester resins at temperatures between 35 and 90℃ was studied using DSC and FTIR. The effect of the degree of resin unsaturation on the curing behaviors was investigated. This experiment also affirmed the shielding effect of network.

14. Experimental results from FTIR and DSC measurements agree with each other reasonably well. The higher the degree of C=C unsaturation per molecule, the higher is the reaction rate. The diffusion-limitation effect is more significant for the polyester resin with a higher degree of unsaturation, leaving more unreacted C=C bonds trapped inside the matrix after vitrification, resulting in lower final conversions of polyester and styrene C=C bonds.

15. 3.2 1H NMR, 13C NMR • Determinating the average sequence length: • Cui J. et al. and Zhao Q. Z. et al. determined the ratio of components in copolyesters and calculated the average sequence length by 1H NMR and 13C NMR spectra. • Zhao F. R. et al. studied the relationship of polybutadiene sequence structure and properties by NMR. They separated different conformers (cis-1,4-, trans-1.4-, 1,2-ethenyl) by thin-layer chromatography(TLC), and determined their contents by 13C NMR. • Dong H. R. et al. and James et al. determined ethylene-propylene mole fractions and methylene number average sequence lengths in ethylene-propylene copolymers by 1H NMR, 13C NMR and FTIR.

16. Determinating the sequence distribution: • Bara et al. obtained compositions of vinyl acetate/methyl acrylate (V/M) copolymer from 1H NMR spectroscopy. The microstructure was obtained in terms of the distribution of V- and M-centered triad sequences from 13C{1H}–NMR spectra of copolymers. Homonuclear 1H-2D-COSY and 2D-NOESY NMR were used to determine the most probable conformer for the V/M copolymer. • Bara and his coworkers also determinated the microstructure (triad) of styrene and methyl methacrylate(S/M) copolymer by 1H NMR, 13C NMR, two-dimensional NMR techniques such as heteronuclear single quantum coherence(HSQC) and heteronuclear multiple quantum coherence(HMQC).

17. Monomer Sequence Distribution in Styrene-Maleic Anhydride copolymers.Bonnie E. Buchak, Kermit C. Ramey.Polymer Letters Edition. Vol. 14, 401-405(1976). The chemical shift of C1(the styrene aromatic carbon directly attached to the polymer backbone) in copolymer

18. 4. Experimental program 4.1 De-crosslinking of cured UPR by alcoholysis or hydrolysis to obtain linear copolymers consisted of fumarate (or maleate) and styrene units. Method A: hydrolysis by KOH Benzene layer MEKP 1. Extraction Cured UPR UP/St Co 2. KOH in methanol 3. Separation Distill Degradation products

19. Program B: alcoholysis by methanol MEKP 1. Extraction Cured UPR UP/St Co 2. Methanol, p-toluenesulfonic acid 3. Filtration VPO Molecular weight Degradation products Acid and hydroxyl values Standard method 1H NMR 13C NMR Calculation Average sequence length Sequence structure

20. 4.2 Analysis of sequence structure of obtained linear copolymers The procedure: Prepare polystyrene, maleate ester copolymer and determinate them by 13C NMR; Prepare styrene-maleate copolymer in different component proportions and determinate them by 13C NMR; (3) Assign the chemical shift of C1 in styrene-maleate copolymer according to the changes of peak and component proportions and estiblish the relationship between chemical shift and characteristic C.

21. 1 C

22. 4.3 Study the effect of conversions, monomer content and curing temperature to the sequence structure of styrene units The effect of monomer content: At the constant of initiator, accelerator and temperature, cure the UP at different St/UP(C=C)(the ratio is 1-3), then degradate the UPR, measure the degradation products and analyze the sequence structure according to the relationship established between δ and C; Curing at different St/UP Degradation by alcoholysis or hydrolysis Analysis: δ & C

23. (2) The effect of curing temperature: At the constant of initiator and accelerator and St/UP(C=C), cure at different temperature (30,40,50, 60,70,80,90℃) , then degradate the UPR, measure the degradation products and analyze the sequence structure according to the relationship established between δ and C; Curing at different temperature Degradation by alcoholysis or hydrolysis Analysis: δ & C

24. (3) The effect of conversions: At the constant of initiator and accelerator, at a temperature, cure the UP and regular sampling, measure the samples by FTIR, then analyze the conversion, and calculate the average sequence length combined with the reactivity ratio; Regular sampling Calculation Average sequence length Curing conversion FTIR

25. At the same time, at the constant of initiator and accelerator, set a temperature, measure the process of curing by isothermal DSC, then calculate the relationship between conversion rate and time, and calculate the average sequence length at different conversion rate combined with the reactivity ratio; α-conversion rate; t-time; Q- the heat of the reaction till to t; Q0- the overall heat of the reaction