Effect of microstructure on the thermo-oxidation of solid isotactic polypropylene-based polyolefins

Figures & data

Polymerisation conditions of PP samples.

				Propylene
Sample	Solvent	Catalyst/Co-catalyst	[Al]/[Zr]	pressure (bar)	Temp. (°C)
PP178.1	Toluene	Si(CH3)2 [Ind]2 ZrCl2/MAO	1639	2	− 10.0
PP147.8	Toluene	Si(CH3)2 [Ind]2 ZrCl2/MAO	1639	2	− 10.0
PP131.9	Toluene	Et[Ind]2 ZrCl2/MAO	1529	2^a	− 36.6
PP99.5	Toluene	Et[Ind]2 ZrCl2/MAO	1529	2	− 18.5
PP92.4	Toluene	Et[Ind]2 ZrCl2/MAO	1529	2	− 10.0
PP77.9	Toluene	Et[Ind]2 ZrCl2/MAO	1529	2	− 5.0
PP53.9	Toluene	Et[Ind]2 ZrCl2/MAO	862	2	10.0
PP39.7	Toluene	Et[Ind]2ZrCl2/MAO	862	2	30.0
PP30.3	Toluene	Et[Ind]2 ZrCl2/MAO	862	2^a	30.0
PP25.4	Toluene	Et[Ind]2 ZrCl2/MAO	862	2^a	30.0

^aThe reaction was allowed to continue without restoring the initial monomer pressure of 2 bar.

Polymerisation conditions of EP copolymers.

				Feeding mixture
				ethylene/propylene	Reaction		Ethylene
Sample	Solvent	Catalyst/Co-catalyst	[Al]/[Zr]	(bar ratio)	pressure (bar)	T (°C)	content
EP0.6	Toluene	Et[Ind]2 ZrCl2/MAO	1529	0.8 10^−2	2.0	− 5.0	0.6
EP1.1	Toluene	Et[Ind]2 ZrCl2/MAO	1529	1.0 10^−2	2.0	− 5.0	1.1
EP3.3	Toluene	Et[Ind]2 ZrCl2/MAO	1529	1.5 10^−2	2.0	− 5.0	3.3
EP6.1	Toluene	Et[Ind]2 ZrCl2/MAO	1529	1.0 10^−2	2.0	− 5.0	6.1
EP5.1	Toluene	Et[Ind]2 ZrCl2/MAO	1529	1.9 10^−2	2.0	− 5.0	5.1
EP6.2	Toluene	Et[Ind]2 ZrCl2/MAO	1529	2.2 10^−2	2.0	− 5.0	6.2
EP10.1	Toluene	Et[Ind]2 ZrCl2/MAO	1529	2.6 10^−2	2.0	− 5.0	10.1
EP11.1	Toluene	Et[Ind]2 ZrCl2/MAO	1529	2.2 10^−2	2.0	5.0	11.1
EP23.3	Toluene	Et[Ind]2 ZrCl2/MAO	1529	10.2 10^−2	2.0	− 5.0	23.3
EP91.2	Toluene	Et[Ind]2 ZrCl2/MAO	1529	8.0	2.0	5.0	91.2
EP97.7	Toluene	Et[Ind]2 ZrCl2/MAO	1529	20.0	2.0	− 5.0	97.7
EP98.1	Toluene	Et[Ind]2 ZrCl2/MAO	1529	38.0	2.0	− 5.0	98.1
EP99.0	Toluene	Et[Ind]2 ZrCl2/MAO	1529	132.0	2.0	− 5.0	99.0
EP99.4	Toluene	Et[Ind]2 ZrCl2/MAO	1529	99.0	2.0	− 5.0	99.4
EP99.6	Toluene	Et[Ind]2 ZrCl2/MAO	1529	66.0	2.0	5.0	99.6
EP99.7	Toluene	Et[Ind]2 ZrCl2/MAO	1529	52.0	2.0	− 5.0	99.7

Polymerisation conditions of PE samples.

				Ethylene
Sample	Solvent	Catalyst/Co-catalyst	[Al]/[Zr]	pressure (bar)	Temp. (°C)
PE366.3	Toluene	Et[Ind]2 ZrCl2/MAO	1529	2	− 5.0
PE242.5	Toluene	Et[Ind]2 ZrCl2/MAO	1529	2	− 5.0

Viscosimetry, DSC and ¹³C-NMR characterisation of PP samples.

	Intrinsic	DSC			^13C-NMR
	viscosity		Crystallinity		mm	mr	rr		2,1-insertions
Sample	(ml g^−1)	Tm (°C)	(wt.%)		(mol.%)	(mol.%)	(mol.%)	mm/rr	(mol.%)
PP178.1	178.1	156.8	52		97.8	1.2	0.6	2.0	0.3
PP147.8	147.8	150.9	48		96.3	1.8	0.9	2.0	0.7
PP131.9	131.9	152.4	37		84.8	8.2	6.9	1.2	0
PP99.5	99.5	152.4	44		90.6	5.5	3.0	1.8	0.6
PP92.4	92.4	146.6	49		93.1	3.9	1.8	2.2	0.8
PP77.9	77.9	148.1	38		86.6	7.7	4.1	1.9	1.1
PP53.9	53.9	144.2	44		88.1	6.8	3.0	2.3	1.3
PP39.7	39.7	142.8	43		90.8	6.6	2.6	2.5	–
PP30.3	30.3	139.8	38		91.5	4.6	2.1	2.2	1.2
PP25.4	25.4	136.9	50		89.4	5.8	3.0	1.9	1.2

Viscosimetry, DSC and ¹³C − NMR characterisation of EP copolymers.

	Intrinsic	DSC			^13C-NMR
	viscosity		Crystallinity		mm	mr	rr		2,1-insertions
Sample	(ml g^−1)	Tm (°C)	(wt.%)		(mol.%)	(mol.%)	(mol.%)	mr/rr	(mol.%)
EP0.6	109.4	145.2	64		93.8	2.7	1.3	2.1	0
EP1.1	105.0	138.7	49		91.2	3.4	1.6	2.1	0
EP3.3	127.4	139.1	61		87.6	3.5	1.6	2.2	0
EP6.1	110.4	134.0	49		78.1	5.0	1.8	2.8	0.8
EP5.1	77.4	131.7	46		82.9	4.3	1.6	2.7	0.48
EP6.2	87.9	109.2	39		82.7	3.7	0.9	4.1	0
EP10.1	105.2	103.9	26		78.9	2.7	1.2	2.2	0
EP11.1	101.8	97.2	25		75.4	2.6	1.0	2.6	0
EP23.3	75.0	144.0	20		52.89	0	0	–	0
EP91.2	195.6	108.2	35		–	–	–	–	–
EP97.7	224.5	116.0	69		–	–	–	–	–
EP98.1	276.1	120.1	59		–	–	–	–	–
EP99.0	294.3	124.5	75		–	–	–	–	–
EP99.4	292.5	123.1	74		–	–	–	–	–
EP99.6	306.3	122.8	65		–	–	–	–	–
EP99.7	344.3	126.7	59		–	–	–	–	–

Viscosimetry and DSC characterisation of PE samples.

	Intrinsic	DSC
	viscosity	Tm (°C)	Crystallinity
Sample	(ml g^−1)		(wt.%)
PE366.3	366.3	128.5	71
PE242.5	242.5	132.9	75

Figure 1 Mechanodynamical loss modulus curve of PP92.4. (○) Experimental, (—) calculated, (····) single components.

Figure 2 Arrhenius plot of t_i for EP6.2. The 1/ T scale is normalised to the melting point.

Figure 3 I_CL kinetics of EP1.1 at degradation temperatures between 90 and 130 °C.

Figure 4 I_CL kinetics of iPP samples at 120 °C: (○) PP178.1, (—) PP147.8, (····) PP131.9, (– – –) PP99.5, (–·–) PP92.4, (□) PP77.9.

Figure 5 I_CL kinetics of propylene-rich EP samples at 120 °C: (—–) EP0.6, (– – –) EP1.1, (····) EP3.3, (–·–) EP5.1, (—) EP6.1, (–··–) EP23.3.

Figure 6 I_CL kinetics of PE and ethylene-rich EP samples at 120 °C: (—–) PE242.5, (—) EP99.7, (– – –) EP99.0.

Figure 7 Photoluminescence emission spectra: (a) PP and propylene-rich EP samples; (b) PE and ethylene-rich EP samples obtained under irradiation at λ _exc = 270 nm and T = - 130 °C after a 0.5 s delay. Samples are identified in the graphs.

Figure 8 Variation of t_i with the molar mass for PP samples (black symbols) and propylene-rich EP copolymers (white symbols).

Figure 9 Variation of t_i with the content of stereo defects for PP samples (black symbols) and propylene-rich EP copolymers (white symbols).

Figure 10 Variation of t_i with the ethylene content.

Figure 11 DSC melting endotherms of PP and propylene-rich EP samples (the ethylene content is indicated on each curve).

Figure 12 Variation of t_i with the ethylene content for the propylene-rich EP copolymers.

Figure 13 Variation of t_i with the ethylene content for the propylene-rich EP samples at 110, 120 and 130 °C. Black points correspond to T_deg < T_m and red points correspond to T_deg > T_m.

Figure 14 Variation of t_i with the total of isotacticity interruptions for PP samples (black symbols) and propylene-rich EP copolymers (white symbols).

Figure 15 Methine window of the ¹³C-NMR spectra for EP0.6, EP1.1 and EP3.3.

Figure 16 Changes in the ¹³C-NMR spectrum with the ethylene content showing the region corresponding to propylene-ethylene insertions of methylene, which are contiguous to methines. The chemical environment of the CH₂ nuclei is shown in scheme 1.

short-legendScheme 1

Figure 17 Variation of E_act of the thermo-oxidation in the solid state with the average isotactic length (n₁) for PP samples (black symbols) and propylene-rich EP copolymers (white symbols). Red points correspond to the E_act values of EP samples degraded in the melt.

Figure 18 Variation of E_act with the ethylene content for the thermo-oxidation of propylene-rich EP copolymers in the solid state (black symbols) and molten state (red symbols). The range of E_act corresponding to PP samples is indicated on the Y-axis.

Figure 19 Variation of t_i with the relative intensity of sub-T_g DMA relaxation.

Figure 20 DSC melting endotherms of PP92.4 (—) and EP23.3 (····).