Determinants of the Purchase of Secondhand Products: An Approach by the Theory of Planned Behaviour

Abstract

In the context of sustainable consumption, this study aims to understand the determinants of the intention to purchase secondhand products, exploring the direct and indirect effect of each in the constructs of the Theory of Planned Behaviour (TPB). To the traditional variables of TPB, Attitude, subjective norm and perception of behavioural control, were added the price, the need for exclusivity, frugality, environmental concern and environmental knowledge. Quantitative approaches were used, data were collected through a questionnaire and 805 responses were analyzed through PLS-SEM. The results revalidated the TPB variables, frugality, price and environmental concern, as determinants of the intention to purchase secondhand products. Price and environmental concern were the greatest influence on purchase intention. The results also reveal differences between younger and older people in relation to secondhand purchasing and sustainable consumption. Environmental concern is only significant in the purchase intention of younger people, because in older people the price prevails as more influential. This study expands TPB, introducing secondhand and sustainability determinants and analyzing the direct and indirect effects of behavioural constructs applied to purchase intention of secondhand products. Firms and brands need to change from linearity to circular production and follow the intentions of consumers to buy secondhand products, especially young consumers.

1. Introduction

Continuing economic growth alongside environmental degradation is not sustainable, and more sustainable lifestyles need to be promoted [1]. According to Majhi [2], it is necessary to bet on education that is to inform consumers about the environmental impacts that our consumption habits cause in the environment and how the degradation of this can have serious consequences for our lives and those of future generations.

More recently, studies have been developed in the area of sustainability in order to find a new balance between man and nature. For example, consumers’ intention to adhere to sustainable behaviours and their motivational factors have been extensively studied by several authors [3,4,5,6,7]. Most of the results show that, effectively, consumers demonstrate intentions to change their habits and this motivation will be greater the greater the environmental knowledge they have [6,8].

Secondhand buying falls within the scope of sustainable consumption, as it allows for the reduction in the waste of resources and excessive consumption [9] motivated by trends such as fast fashion. In the literature there are several studies that focus on the intention to buy secondhand clothes [10,11,12,13], but there are few who have extended the research to different types of products [14,15]. Some have revealed that the motivational factors for buying used products are mostly economic and hedonic [15,16], with few that deepen the connection with environmental awareness. However, today, with the growing call for attention to environmental issues and sustainability, this can become a central focus that motivates the acquisition of secondhand products. In a study of French consumers, they said they already buy or are willing to buy secondhand products in order to protect the environment [17]. Known studies have identified several factors, but as far as we know, there are few studies that use the theory of planned behaviour (TPB) in the context of secondhand purchase and sustainability behaviour.

So, two questions arise: How can we extend TPB to predict the purchase intent of secondhand products? What factors have a greater influence on the intention to purchase secondhand products?

To close the gap found in the literature related to the positioning of secondhand purchases in the context of sustainability and the extension of the TPB model to understanding the motivations for buying secondhand products, this study aims to understand the impact of different factors, related to the sustainability behaviour on the purchase intention of secondhand products, exploring the direct and indirect effect of each on the TPB constructs.

Price, the need for exclusivity and frugality were adapted from previous studies and introduced as antecedents of the TPB model. The environmental issue is also considered through two variables, one that represents the emotional side, that is, the environmental concern; and the other the cognitive side, that is, environmental knowledge.

Expectations point to a high growth of the secondhand market that can compete and threaten traditional markets as well as the identification of the overlap of environmental factors with economic factors as key drivers for this consumption [18].

From a management point of view, it is necessary to understand current consumer trends so that strategies can be developed that accompany this development and at the same time, continue to satisfy consumers. As they are increasingly aware and thoughtful in the purchases they make, integrating sustainability into business is a must.

This paper is divided into seven sections: introduction, theoretical framework and hypotheses, methodology, results, discussion as well as the conclusion, limitations and future research.

2. Theoretical Framework and Hypotheses

2.1. Theory of Planned Behaviour (TPB)

In an attempt to better understand and predict customers’ intentions to adhere to certain activities, many researchers have turned to the theory of planned behaviour [19,20]. Theory of Planned behaviour (TPB) is a social and psychological model of consumer behaviour that proposes that a set of three variables are the main explanatory factors of an individual’s behavioural intentions and later of their behaviour [19]. This is because, the stronger the intention (INT) of someone to engage in the performance of a behaviour, the more likely it is to occur [19].

The first variable, the attitude (AT) towards a behaviour, refers to the degree of evaluation and/or positive or negative appreciation which a person has about the behaviour in question [19]. The second antecedent of intention, the subjective norm (SN), is the social pressure perceived by the consumer and exerted, for example, by friends and family to perform a certain behaviour [19]. Finally, the perception of behavioural control (PBC) is the perception of the individual relative to the ease or difficulty in exercising their behaviour [19].

The theory of planned behaviour has already been used in various behavioural studies from secondhand purchase of children’s clothing [21], choice of organic menus in restaurants [22], purchase of green products [7], reduction in car use [23], among others. It is especially used in the area of sustainability to analyse the sustainable behaviour of consumers [1,24].

As to limitations of the theory, some authors point out that, in some studies, the variables do not reveal any effect on intention. However, they often do not have the same importance in predicting intention [25], varying according to the type of behaviour and the situation [19]. Of the three factors, attitude has proved to be the most significant in predicting behaviour [19] and the subjective norm the least significant [26]. However, regarding the purchase intention, there was no such difference between the relationship with attitude and the subjective norm [25]. On the contrary, there seems to be a strong association between the subjective norm and behaviours linked to social responsibility, especially in collectivist cultures [25,27]. As there is a tendency to follow the standards of society in order to be accepted by it, the probability of acquiring used products will be greater if there is incentive from third parties [14]. A study developed in China showed that an individual’s intention to buy secondhand clothing increases when they observe other consumers doing so [16]. The study by Hansen et al. [28] also points out that the subjective norm plays a more important role in uncertain situations, because the word of the family members will have a greater weight on the decision. Some individuals still do not feel comfortable buying in secondhand markets, so third-party referrals may have an influence on purchase intent [29]. Regarding the perception of behavioural control, for it to have a significant impact it is necessary to have available the various resources necessary to carry out the behaviour [20]. Seo & Kim’s [29] study found a positive relationship between attitude and intent to buy secondhand clothing in nonprofit stores, but on the contrary, subjective norm and perception of behavioral control revealed no influence on intention. In the study by Han & Stoel [25] a strong association was revealed between the three behavioural antecedents and the intention to buy, the most significant being the relationship with the attitude, followed by the subjective norm and finally, the perception of behavioural control. In another context, the study by Varah et al. [7], showed that the intention to purchase green products is predicted by the three components of the theory of planned behaviour. The research of Kumar et al. [30], on the intention to purchase eco-friendly clothing, also validated the relevance of the three variables, however, the role of attitude as the main factor was highlighted.

The results of previous studies show inconsistency and the need to continue to deepen and test the role of behavioral antecedents on the intention to perform certain behaviours.

The present study assumes the hypothesis that behavioural variables positively influence the intention to purchase secondhand products, considering a positive and easy-to-perform behaviour, as well as socially accepted.

Hypothesis 1.

Attitude (a), subjective norm (b) and perception of behavioural control (c) have a positive influence on the intention to purchase secondhand products.

The theory of planned behaviour can be extended by adding other variables in order to better understand the intention about a given behaviour [19]. In this study we extend TPB by introducing different variables identified in previous studies as influencers of secondhand purchases.

2.2. Price Influence

Price has always been seen as one of the main motivational factors of buying secondhand products [15,31]. As these are products that have already been used, the amount charged to the second buyer will be lower than the original value [15,32,33], unless it is considered a rare good [34].

Within the secondhand market are recent products or products from past eras, the latter sometimes being more expensive than the initial price since they are no longer produced and are not available for sale [34]. However, in most situations, many consumers are able to simultaneously purchase numerous goods, which are in perfect condition, and save [31] since the costs are lower than normal [11,15]. Regardless of the other factors, the pleasure gained by buying good products at lower prices continues to have its weight in consumers’ decisions, for example for the purchase of secondhand clothing [16,35]. This economic variable is related to the enthusiasm, pointed out by some studies, to hunt and find bargains [15].

In addition, there are consumers who wish to have a more sustainable behaviour and buy green products, but as a rule the prices of these are higher compared to traditional products and this is a barrier to consumption [36,37]. As much interest as they may have, sometimes they do not have the financial availability to do so and therefore, the purchase of secondhand products can be a more affordably sustainable option [38].

In this sense, it is assumed that the lower prices practiced facilitate the practice of this action, positively influencing the attitude, the perception of behavioural control and the intention to buy. To our knowledge, the price variable has not yet been previously added to TPB, so in this sense the following research hypothesis is proposed:

Hypothesis 2.

Price has a positive influence on attitude (a), perception of behavioural control (b) and intention to purchase secondhand products (c).

2.3. Need for Exclusivity

The concept of the need for exclusivity arises from the theory developed by Snyder and Fromkin [39], which analyses the need for the individual to see and show himself differently from others. This individuality can be expressed in different ways: displaying the possession of unique products, mode of interaction, in-depth knowledge about themes, among others [39]. According to Tian et al. [40] (p. 52), the need for exclusivity is defined as “the trait that leads to the search for difference in relation to others, through the acquisition, use and/or disposition of consumer goods in order to develop and improve their self-image and social image”. In the market of used products, it is possible to find a wide range of products, from recent to old. A very attractive factor in these articles is their unique and differentiating character in relation to the products that are found in ordinary stores [15]. Often, they are products which, even if recent, are no longer produced and therefore are not available [40]. Customers of secondhand products see here an opportunity to escape the “ordinary” and differentiate themselves from the rest [15,41]. They seek to build and transmit their identity and personality through the originality of their articles. By fleeing the system and goods en masse, these individuals are simultaneously running away from the patterns. This status of differentiation is even greater by displaying in unique pieces and dressing differently [42,43]. If on the one hand this need can be a barrier to the consumption of sustainable products, since usually the range of products is reduced, on the other hand this can be a motivation for buying used products [42,43]. Secondhand pieces are then a means to realise this desire for individuality and therefore, there is a positive relationship between the need for unique pieces and the intention to buy secondhand [11,15]. Personality traits may have an influence on the intention to perform social and environmental behaviours through the dimensions of TPB [19]. These individual traits mainly influence attitude and social norms [42,44]. In the research of Lang & Armstrong [42] this need was positively related only to the subjective norm and the intention to change clothes, having no influence on the attitude and perception of behavioural control. Thus, we postulate the following hypothesis:

Hypothesis 3.

The need for exclusivity has a positive influence on the subjective norm (a) and the intention to purchase secondhand products (b).

2.4. Frugality

Frugality is considered a lifestyle. This trait characterises the degree to which consumers’ acquisition of goods and services are restricted in order to achieve certain long-term goals [45]. For example, by purchasing secondhand products they can save and use this money for other purposes [32]. In addition to the monetary issue, it is also associated with the efficient use of resources, that is, using a product until it is useless [13]. In this follow-up, a frugal consumer is considered less materialistic, less impulsive and more thoughtful in their decisions [32,45]. This weighting also leads to a preference for products that have a high quality and durability, in order to extract the highest possible value from the purchase made [46]. Within the secondhand market, there is the luxury products segment that allows one to obtain these products considered premium [34] or find branded products.

Frugality is also associated with recycling and reuse behaviors of objects [32,33]. Secondhand buying promotes this behaviour, since purchased products have been discarded by third parties and are being reused by interested parties [13]. The studies by Cervello et al. [32] and Zaman et al. [13] considered frugality as one of the main influencers in the purchase of secondhand garments, supporting the results, previously obtained by Guiot and Roux [15]. The study by Seo & Kim [29] introduced the variable frugality in TPB, however, it only evaluated its relationship with attitude.

Although frugality is strongly present in the literature related to secondhand purchases, as far as we know, its relationship with the behavioural variables of TPB has never been studied, hence it is introduced in the developed model and the following hypothesis is proposed:

Hypothesis 4.

Frugality has a positive influence on attitude (a), subjective norm (b), perception of behavioural control (c), and intention to purchase secondhand products (d).

2.5. Environmental Concern

According to some studies conducted [14,25,47], consumers are increasingly concerned and emotionally connected with environmental problems and threats, seeking to change their consumption habits [14] with the aim of protecting the environment [30]. The concept of environmental concern refers to the “degree to which people are aware of problems related to the environment, support efforts to solve them, and show a willingness to personally contribute to the solution” [48].

This variable has been added to the TPB by several authors, contributing to the explanation of the intention to make sustainable purchases [25].

It was found that environmental concern (EC) motivates the intention to purchase eco-friendly clothing [30] and green products [7].

Relative to the influence of environmental concern on the purchase intention of green products, the research of Paul et al. [47] corroborated the positive results of previous research but added a positive relationship on the three behavioural variables of Ajzen’s theory. Studies by Rausch and Kopplin [6] and Seo and Kim (2019) [29] inferred that environmental concern influences not only the intention to buy sustainable clothing and used clothing respectively, but also attitude. By introducing the variable into the theory of planned behaviour, Chen & Tung [49] validated the influence on attitude, subjective norm, and perception of behavioural control in relation to visiting green hotels.

The purchase of used products is a way to reduce the impact on the environment, reducing the production of new products and, therefore, the consumption of more resources does not occur [11,38]. In this sense, the following research hypothesis is proposed:

Hypothesis 5.

Environmental concern has a positive influence on attitude (a), subjective norm (b), perception of behavioural control (c) and intention to purchase secondhand products (d).

2.6. Environmental Knowledge

In a more cognitive aspect, we sought to analyse the relationship between environmental knowledge and behavioural intentions, in particular, the intention to purchase sustainable products or adherence to responsible behaviours.

Environmental knowledge (EK) corresponds to “individual knowledge of facts and concepts about the environment and ecosystems” [50] (p. 48). This requires knowledge about the environmental problems that are largely generated by human actions [21,27]. While environmental knowledge translates into the information that the consumer has about the origin of environmental problems, environmental concern evaluates these causes and triggers a reaction that can be verified by the change in behaviour [21].

The positive relationship between environmental knowledge and the intention to perform sustainable behaviours is well evidenced in studies. Consumers who have greater environmental knowledge, as well as greater concern, are more predisposed to the consumption of sustainable products [6,8].

In the study by Ko & Jin [51] the results also verified the existence of a positive relationship between environmental knowledge and attitude about buying green products, as well as with the perception of behavioural control. According to Peña-Vinces et al. [21], knowledge will influence the decision of parents to buy or rent secondhand clothes for babies. According to the literature review, environmental knowledge seems to be a significant antecedent of responsible attitudes and intentions towards the planet, and this can be represented by the purchase of used products. In this connection, the following hypothesis has been constructed:

Hypothesis 6.

Environmental knowledge has a positive influence on attitude (a), perception of behavioural control (b) and intention to purchase secondhand products (c).

Following the hypotheses presented, the following conceptual model emerges, developed based on the research and literature review carried out (see Figure 1).

3. Methodology

This study aims to understand the impact of different factors on the purchase intention of secondhand products, exploring the direct and indirect effect of each in the constructs of the extended Theory of Planned Behaviour. This study follows a quantitative methodology considered adequate to test our model and analyses the causal relationships in the TPB and other variables [52].

For data collection we used a self-administered questionnaire. The questionnaire is divided into two parts. The first part aims to evaluate the impact of the different factors of purchase intent; the second part collects the sociodemographic characteristics of the sample. Price and the need for exclusivity were measured using four and three items, respectively, adapted from Padmavathy et al. [53] and Guiot & Roux [15]. The frugality of consumers was based on the eight items adapted from Lastovicka et al. [45]. Environmental concern was measured based on four items by Rausch and Kopplin [6]. Regarding environmental knowledge, the four items were adapted from La Trobe & Acott [54] and Peña-Vinces et al. [21]. Regarding the constructs of the Theory of Planned Behaviour, the items were adapted from previous studies based on Ajzen [52]. The attitude towards purchase intention was measured according to the six-item scale of Yazdanpanah & Forouzani [55]. Both the subjective norm and the perception of behavioural control were assessed through three and four item scales, respectively, adapted from Borusiak et al. [14]. Finally, the intention to purchase secondhand products was measured by four items adapted from Yazdanpanah & Forouzani [55] and Armitage et al. [56]. All items were measured using a five-point Likert scale. In the last section of the questionnaire, questions regarding the sociodemographic characteristics of the sample were asked.

Data were collected between February and March of 2021, on social networks and the Amazon MTurk platform, thus allowing for a more diverse sample in relation to sociodemographic characteristics to be obtained [57] as well as increasing the quality of the data collected [58].

A convenience sample of 805 valid responses were obtained and used in the analysis. For data analysis, the PLS-SEM method was used through the Smart PLS 3.0 software. This method has been used in studies of several areas, since this allows for the study of complex models measuring direct and mediation relationships between different variables [59,60]. In fact, this method proved to be the most appropriate for the proposed research model.

4. Results

This section characterises and analyses the data collected. Validity and reliability tests were performed. The hypotheses were tested through the PLS-SEM model and the existence of mediation effects was verified. Finally, a multigroup analysis was performed in order to increase knowledge about possible generational differences.

4.1. Sample Characterisation

Regarding the sociodemographic characterisation of the sample, most of the respondents were female (N = 544, 68%), a minority were male (N = 251, 31%) and the rest did not specify (N = 10, 1%). Regarding the age groups of the respondents, the majority were between 18 and 24 years (N = 312, 39%), followed by 25–34 years (N = 178, 22%) and 35–44 years (N = 153, 19%). As for academic qualifications, the largest number of respondents had a bachelor’s degree (N = 367, 46%) and secondary education (N = 241, 30%). Regarding net monthly income, the majority answered that they had no income (N = 228, 28%), which can be justified by the fact that young people represent a large portion of the sample and may only be students. However, many participants reported an income between EUR 700–1399 (N = 181, 22%) and up to EUR 699 (N = 122, 15%).

The main country of origin of the respondents was Portugal (N = 492, 61%), since the questionnaire in Portuguese was disseminated on social networks for a longer period of time. However, through the MTurk platform, responses were obtained from several countries, such as the United States of America (N = 121, 15%) and India (N = 59, 7%).

4.2. Reliability and Validation of Measures

To verify the reliability and validity of the constructs, several indicators were used: the individual reliability of the items, the composite reliability (CR), Cronbach’s alpha α (CA) and the AVE criterion (Average Variance Extracted) [59,61].

The results obtained by the PLS-SEM, represented in

Table 1. Reliability and validity of the model.

Dimension	Item	L	α	Mean	SD	CR	AVE
Attitude (AT)	AT1	0.806	0.911	4.068	1.032	0.931	0.691
	AT2	0.817		4.119	1.03
	AT3	0.82		4.065	1.064
	AT4	0.842		4.18	0.996
	AT5	0.867		4.01	1.05
	AT6	0.837		4.045	1.022
Subjective Norm (SN)	SN1	0.909	0.877	2.691	1.232	0.915	0.731
	SN2	0.897		2.631	1.234
	SN3	0.72		2.703	1.196
	SN4	0.879		2.688	1.185
Perception of behavioural control(PBC)	PBC1	0.797	0.765	3.836	1.143	0.863	0.677
	PBC2	0.865		4.193	1.001
	PBC3	0.806		3.667	1.232
Price (PR)	PR1	0.892	0.884	3.779	1.114	0.92	0.741
	PR2	0.878		3.901	1.034
	PR3	0.874		3.928	1.049
	PR4	0.798		3.755	1.123
Need for exclusivity(NE)	NE1	0.893	0.905	2.508	1.395	0.941	0.841
	NE2	0.935		2.445	1.397
	NE3	0.923		2.493	1.369
Frugality (FRU)	FRU1	0.718	0.858	4.513	0.762	0.888	0.5
	FRU2	0.707		4.492	0.784
	FRU3	0.81		4.535	0.712
	FRU4	0.739		4.334	0.887
	FRU5	0.757		4.588	0.767
	FRU6	0.624		4.25	0.885
	FRU7	0.639		4.284	0.88
	FRU8	0.641		4.251	0.891
Environmental concern (EC)	EC1	0.887	0.896	4.337	0.882	0.928	0.763
	EC2	0.883		4.376	0.863
	EC3	0.872		4.127	0.986
	EC4	0.85		4.378	0.899
Environmental knowledge (EK)	EK1	0.799	0.881	4.441	0.839	0.908	0.585
	EK2	0.717		4.328	0.88
	EK3	0.79		4.399	0.844
	EK4	0.769		4.502	0.791
	EK5	0.746		4.176	0.901
	EK6	0.696		4.434	0.946
	EK7	0.826		4.564	0.761
Intention (INT)	INT1	0.897	0.939	4.283	0.957	0.956	0.846
	INT2	0.937		4.143	1.022
	INT3	0.934		3.971	1.111
	INT4	0.91		4.157	1.001

, reveal the individual reliability of the construct indicators and all items reached values elevated to 0.5 [59,61]. In this way, no items were deleted. Composite reliability was also achieved, since the values are between 0.863 and 0.956, all higher than the recommended 0.7 [62]. Considering 0.7 the minimum acceptable value for Cronbach’s α, the reliability of the constructs is confirmed. The values are between 0.765 and 0.939. To measure convergent validity, the AVE criterion was used, which must be greater than 0.5 [63]. Validity was reached, since the AVE of all constructs (with the exception of frugality) exceeded the appropriate value, ranging from 0.585 to 0.846. Although frugality presents a stroke of only 0.500, as CR is higher than 0.6, the convergent validity of the construct is maintained [63].

To evaluate the discriminant validity, the Fornell and Larcker criterion was used, which confirms its validity if the square root of the AVE is superior to the correlations of the constructs [63]. As shown in

Table 2. Fornell and Larcker criterion.

	AT	EC	EK	FRU	INT	NE	PBC	PR	SN
AT	0.832
EC	0.241	0.873
EK	0.232	0.732	0.765
FRU	0.377	0.468	0.529	0.707
INT	0.681	0.289	0.265	0.428	0.920
NE	0.264	−0.019	−0.113	−0.009	0.257	0.917
PBC	0.408	0.061	0.061	0.273	0.591	0.242	0.823
PR	0.500	0.050	0.092	0.357	0.589	0.315	0.538	0.861
SN	0.308	0.066	−0.017	0.081	0.391	0.436	0.398	0.341	0.855

, the square root of the AVE for each variable (indicated in bold) is greater than the correlations between the remaining constructs. Thus, according to this criterion there is discriminant validity.

In summary, reliability, convergent validity and discriminant validity have been proven. The model has been validated and it has been confirmed that the scales used are adequate to measure the respective variables.

4.3. Hypothesis Testing

After verifying the validity of the items, hypothesis testing was performed using the bootstrapping procedure with 5000 samples.

Table 3. Results.

	Hypothesis		Coef.	t Value
H1a	Attitude → Intention		0.395	10.552 ***
H1b	Subjective Norm → Intention		0.087	3.218 **
H1c	PBC → Intention		0.27	8.170 ***
H2a	Price → Attitude		0.439	11.133 ***
H2b	Price → PBC		0.502	15.465 ***
H2c	Price → Intention		0.186	5.640 ***
H3a	NE → Subjective Norm		0.437	13.284 ***
H3b	NE → Intention		−0.005	0.196 ns
H4a	Frugality → Attitude		0.15	3.690 ***
H4b	Frugality → Subjective Norm		0.064	1.917 ns
H4c	Frugality → PBC		0.115	2.926 **
H4d	Frugality → Intention		0.067	2.101 **
H5a	EC → Attitude		0.143	3.435 **
H5b	EC → Subjective Norm		0.045	1.252 ns
H5c	EC → PBC		0.035	0.788 ns
H5d	PA → Intention		0.115	3.166 **
H6a	EK → Attitude		0.007	0.162 ns
H6b	EK → PBC		0.072	1.493 ns
H6c	EK → Intention		0.022	0.557 ns
	R square
	Attitude	0.312
	Subjective Norm	0.199
	PBC	0.299
	Intention	0.639

Note: Coefficients|** p < 0.05; *** p < 0.001; ns: not significant.

presents the results obtained for the coefficients, the values of t and p.

The results of the coefficient of determination show that the various antecedents explain 31.2% of the variance of attitude, 19.9% of the variance of the subjective norm and 29.9% of the variance of the perception of behavioural control. In turn, the antecedents and constructs of TPB (attitude, subjective norm and perception of behavioural control) explain 63.9% of the variance of purchase intention.

H1 proposes that attitude (H1a), subjective norm (H1b) and PBC (H1c) positively affect the intention to purchase secondhand products. The results validate the positive relationship for the three constructs, and attitude (coef = 0.395, p < 0.001) plays a higher role than the subjective norm (coef = 0.087, p < 0.05) and PBC (coef = 0.270, p < 0.001).

H2, which proposes that price (PR) positively influences attitude (H2a) (coef = 0.439, p < 0.001), PBC (H2b) (coef = 0.502, p < 0.001) and directly intention (H2c) (coef = 0.186, p < 0.001), is supported.

H3 proposed that the need for exclusivity (NE) positively influences the subjective norm (H3a) and intention (H3b). However, NE is not significant in intention only about the subjective norm (coef = 0.437, p < 0.001). Thus, only H3a is empirically validated.

H4 proposes that frugality positively affects the three constructs of TPB and intention. As shown in Table 3, the effect of frugality is not significant in the subjective norm but is in attitude (coef = 0.150, p < 0.001), PBC (coef = 0.115, p < 0.01) and intention (coef = 0.067, p < 0.05). Therefore, H4a, H4c and H4d are validated and H4b rejected.

H5 proposed that environmental concern (EC) positively influences the different behavioural variables of TPB and intention. However, EC only significantly affects attitude (coef = 0.143, p < 0.05) and intention (coef = 0.115, p < 0.01). In this way, H5a and H5d are confirmed. The results reject H6, which means that the effect of environmental knowledge (EK) is not significant on attitude (H6a), PBC (H6b) and intention (H6c).

To test the existence of mediation effects, indirect effects and adjusted confidence intervals were extracted and represented in

Table 4. Mediation effect.

	Coefficient	Std. Error	Valor t	95% IC Bias
				Lower	Upper
PR → AT → INT	0.173	0.025	6.900 ***	0.128	0.226
PR → PBC → INT	0.136	0.019	7.197 ***	0.102	0.177
NE → SN → INT	0.038	0.012	3.127 **	0.015	0.064
FRU → AT → INT	0.059	0.017	3.557 ***	0.028	0.095
FRU → SN → INT	0.006	0.003	1.601 ns	0.000	0.014
FRU → PBC → INT	0.031	0.011	2.717 **	0.011	0.055
EC → AT → INT	0.056	0.018	3.102 **	0.023	0.094
EC → SN → INT	0.004	0.004	1.105 ns	−0.001	0.013
EC → PBC → INT	0.009	0.012	0.779 ns	−0.014	0.034
EK → AT → INT	0.003	0.017	0.161 ns	−0.031	0.036
EK → PBC → INT	−0.019	0.014	1.441 ns	−0.047	0.005

Note: Bootstrapping n = 5000 sample; Coef—Coefficient; Std. E—Standard Error; IC—95% Confidence Interval Bias Corrected (Lower and Upper Bounds) ** p < 0.05; *** p < 0.001; ns: no significance.

. In the theoretical model described (Figure 1), attitude, SN and PBC can generate this mediating effect between the antecedent variables and the intention to purchase secondhand products.

Starting with the mediation effect of the attitude between price and intent, the IC for the indirect effect does not include zero (95% IC [0.128, 0.226]). The same happens in the PBC’s mediation effect between price and intent, the IC for the indirect effect does not include zero (95% IC [0.102, 0.177]). The results show that attitude and PBC mediate the relationship between price and intention and as the direct effect is also significant (coef = 0.186, p > 0.001), in both cases, it is a complementary mediation [64].

On the mediation of the subjective norm between the need for exclusivity and intention, the IC for the indirect effect excludes zero (95% IC [0.015, 0.064]). It was found that SN mediates the relationship between NE and intention, but since the direct effect is not significant (coef = −0.005, p > 0.05), it is only an indirect mediation [64].

Attitude (95% IC [0.028, 0.095]) and PBC (95% IC [0.011, 0.055]) mediate the relationship between frugality and intention, since IC for the indirect effect exclude zeros. As the direct effect is also significant (coef = 0.067, p < 0.05), it is a complementary mediation [64].

However, the same is not true in the mediation of the subjective norm between frugality and intention. As the IC for the indirect effect includes zero (95% IC [0.000, 0.014]), SN does not measure the relationship, but the direct effect is significant (coef = 0.067, p < 0.05), so it is a direct effect without mediation (direct only non-mediation) [64].

Regarding the mediation effect of the attitude between environmental concern and intention, the IC for the indirect effect excludes zero (95% IC [0.023, 0.094]), showing that attitude mediates the relationship. As the direct effect is also significant (coef = 0.115, p < 0.05), it is a complementary mediation [64].

In the case of IC for the indirect effect of the subjective norm (95% IC [−0.001, 0.013]) and PBC (95% IC [−0.014, 0.034]), these include the zeros and therefore they do not mediate the relationship but the direct effect is significant (coef = 0.115, p < 0.05). Therefore, it corresponds to a direct-only non-mediation effect [64].

Finally, in the case of environmental knowledge, attitude and PBC do not mediate the relationship between EK and intention, since both IC for indirect effects include zeros (95% IC [−0.031, 0.036] and (95% IC [−0.047, 0.005]), respectively. In addition, the direct effect is also not significant (coef = 0.022, p > 0.05). Therefore, there is no effect (no effect non mediation) [64].

4.4. Multigroup Analysis

To test the results of different groups, a multigroup analysis was conducted, although this analysis did not correspond to the main objective of the study. The data were grouped in order to obtain only two groups. The first group is young people between 18 and 34 years old (young), the second is composed of individuals over 34 years old (old). This analysis was carried out in order to verify possible behavioural differences between individuals of different ages and which factors have the greatest influence on the intention to purchase secondhand products in each age group.

The estimated coefficients of the three groups and the estimated differences between them were recorded in

Table 5. Multigroup analysis.

	Hypothesis	Coef (Young)	Coef (Old)	Difference
H1a	Attitude → Intention	0.446 ***	0.285 ***	0.161 **
H1b	Subjective Norm→ Intention	0.077 **	0.108 **	−0.031 ns
H1c	PBC → Intention	0.247 ***	0.307 ***	−0.061 ns
H2a	Price → Attitude	0.362 ***	0.548 ***	−0.186 **
H2b	Price → PBC	0.446 ***	0.576 ***	−0.131 **
H2c	Price → Intention	0.151 ***	0.256 ***	−0.106 ns
H3a	NE → Subjective Norm	0.401 ***	0.470 ***	−0.069 ns
H3b	NE → Intention	0.002 ns	−0.016 ns	0.018 ns
H4a	Frugality → Attitude	0.121 **	0.143 **	−0.023 ns
H4b	Frugality → Subjective Norm	−0.040 ns	0.168 ***	−0.209 **
H4c	Frugality → PBC	0.108 **	0.104 ns	0.004 ns
H4d	Frugality → Intention	0.060 ns	0.068 ns	−0.008 ns
H5a	EC → Attitude	0.289 ***	−0.001 ns	0.290 ***
H5b	EC → Subjective Norm	0.088 **	0.020 ns	0.068 ns
H5c	EC → PBC	0.096 ns	−0.033 ns	0.130 ns
H5d	PA → Intention	0.133 **	0.069 ns	0.064 ns
H6a	EK → Attitude	0.004 ns	0.018 ns	−0.014 ns
H6b	EK → PBC	−0.122 ns	0.010 ns	−0.132 ns
H6c	EK → Intention	0.013 ns	0.039 ns	−0.026 ns

Note: Bootstrapping n = 5000 sample; ** p < 0.05; *** p < 0.001; ns: no significance.

.

The results suggest some significant differences between the estimated coefficients of the two groups. The main differences were between attitude and intention (p < 0.05), price and attitude (p < 0.05), price and perception of behavioural control (p < 0.05), frugality and subjective norm (p < 0.05), environmental concern and attitude (p < 0.001).

Attitude has a greater impact on purchase intent for younger consumers (coef = 0.446, p < 0.001) compared to older consumers (coef = 0.285, p < 0.001). The former believe more in the positive impact of secondhand buying than the latter. For older people, price has a greater impact on attitude (coef = 0.548, p < 0.001), while for younger people, its impact is less strong (coef = 0.362, p < 0.001). In the case of the effect of price on PBC, the effect is greater on older individuals (coef = 0.576, p < 0.001) than on young people (coef = 0.446, p < 0.001). Regarding frugality, there were also different effects. Its effect on the subjective norm is significant (coef = 0.168, p < 0.001) in the elderly, but not in the younger.

Finally, the effect of environmental concern on attitude was significant only in younger people (coef = 0.289, p < 0.001), and not in the case of individuals older than 34 years.

The results allow us to infer the impact of different factors on the mediation effect of behavioural variables and generational differences.

Table 6. Validation of hypotheses.

	Hypothesis	Validation
H1a	Attitude → Intention	Confirmed
H1b	Subjective Norm→ Intention	Confirmed
H1c	PBC → Intention	Confirmed
H2a	Price → Attitude	Confirmed
H2b	Price → PBC	Confirmed
H2c	Price → Intention	Confirmed
H3a	NE → Subjective Norm	Confirmed
H3b	NE → Intention	Rejected
H4a	Frugality → Attitude	Confirmed
H4b	Frugality → Subjective Norm	Rejected
H4c	Frugality → PBC	Confirmed
H4d	Frugality → Intention	Confirmed
H5a	EC → Attitude	Confirmed
H5b	EC → Subjective Norm	Rejected
H5c	EC → PBC	Rejected
H5d	PA → Intention	Confirmed
H6a	EK → Attitude	Rejected
H6b	EK → PBC	Rejected
H6c	EK → Intention	Rejected

presents the validation of twelve hypotheses and the rejection of seven hypotheses.

5. Discussion

This study sought to extend the theory of planned behaviour, analysing the direct and indirect effects between different factors and behavioural variables, measuring the impact on secondhand purchase intention and, consequently, more sustainable consumption. First, the study validates the role of attitude, subjective norm and perception of behavioural control in purchase intention [7,14,19], as the TPB maintains. In addition, the greatest significance of attitude and PBC was confirmed, with the subjective norm being the least significant about the intention to purchase secondhand products [26]. As argued by the author Ajzen [19] the weight of the variables varies according to the context and the type of behaviour to be performed.

From the results we can infer that the evaluation of secondhand purchases as a positive behaviour, as well as the perception of the behaviour as easy to perform, are more decisive factors than the social pressure exerted to do so. However, this contradicts Seo & Kim’s [29] proposal that the PBC would have no influence due to consumers’ lack of availability to buy secondhand. This is perhaps justified by the growing online sales and physical markets of secondhand goods that facilitate access to these products.

Another fact acquired is related to the significance of the attitude being superior in young people, demonstrating that they have a more positive position on secondhand buying. This conclusion supports the assertion that the predisposition to purchase is greater in younger people [38].

The results also allowed us to identify which antecedents cause a greater effect on the dimensions of TPB and consequently on purchase intention. Regarding price, this study corroborates the previously defended conclusions that this is one of the main factors that motivates the purchase of used products [15,18,31]. However, the price has a positive impact mostly on the perception of the possibility of performing the behaviour. This is because lower prices make products more affordable by allowing consumers, especially those with lower incomes, to have more sustainable consumption through the purchase of secondhand products [15,31].

Although previous studies have demonstrated a transition from economic to environmental factors [29], the analysis identified price as still being the antecedent with the greatest influence on behavioural constructs and intention.

Analysing by age groups, the relationship between price and behavioural variables, attitude and PBC, is more significant in older people. This observation contradicts the study of purchase intention among Chinese consumers in which only the youngest (post 90s) revealed an influence of price [16].

In turn, the need for exclusivity only proved significant on the subjective norm, partially supporting the results obtained by Lang & Armstrong [42]. NE increases the impact of social pressure for sustainable behaviour but is not directly significant on intention. Thus, the results on NE were different from previous studies, since this individuality was recurrently pointed out by consumers in different surveys [15,53]. Perhaps their influence is higher in fashion consumption, such as clothing and accessories, as they are among the most visible goods by third parties. Another justification may be that the desire for similarity to those around us, as a sense of belonging, overrides the desire for differentiation. The authors of Xu et al. [27] state that the relevance of the need for exclusivity varies according to the collectivist or individualistic level of the culture of individuals. The respondents did not in fact demonstrate a great need to differentiate themselves from the others (M < 3).

Previous studies pointed to frugality as a motivational trait of consumers of used products [13,15,32]. However, we were not aware of the detailed evaluation of it in the TPB and therefore we decided to do so. Frugality is related to sustainable behaviours linked to recycling. Respondents believe that they should not buy a new item while one is still useful (M < 5), which often happens with used products that are dispensed by some and repurposed by others. Frugality proved to be significant in attitude, PBC and intention, which despite the lack of theoretical support under its influence on the constructs, ends up highlighting its impact on sustainable consumption, as verified in previous studies [13,15,32]. Frugal consumers demonstrate a positive attitude about secondhand buying behaviour and perceive the action as something feasible. The positive relationship found with the attitude contradicts Seo & Kim [29], who indicated it as not significant for the intention to buy secondhand clothes. However, its effect is not significant on the subjective norm. The results also oppose the study by Fernando et al. [46] that indicated consumers of used products as less frugal than consumers of new products, contrary to other research. Additionally, the relationship between frugality and subjective norm is only significant in older consumers. This may be connected with the fact that as a rule adults think more about the types of goods they buy in order to get the most out of them.

Regarding environmental concerns, the results support the conclusions of some existing studies and contrast others. Our research shows an influence of EC only on attitude and purchase intent, as advocated by some authors [6,29]. This confirms that, effectively, consumers who are more concerned about the environment consider and seek more sustainable consumption alternatives [14,30,65]. Respondents were highly concerned about the future of the environment and the negative consequences of unsustainable behaviour (M < 5). The EC proved to be the second most significant antecedent in the intention to purchase used products and may be an indicator of the growing concern with environmental impacts, as verified in the analysis of the profile of the ecologically conscientious consumer [65]. In addition to these results, it was also found that the relationship between EC and attitude is not significant in older individuals and only in younger individuals. This point contradicts the conclusions of the study by Yan et al. [31], on the purchase of secondhand clothes, in which EC was not presented as a motivational factor among young students. On the other hand, it supports studies that point to young people (post 1980s) as the greatest environmental protectors, having grown up in an era where the theme is recurrent [16].

Finally, the results of environmental knowledge did not corroborate previous studies that pointed to it as being both an influencer of the TPB constructs and of the purchase intention itself [21,51]. The lack of knowledge about environmental impacts can in turn become a barrier to the modification of unsustainable consumption [21]. The emotional side overlaps with the cognitive side demonstrating that the change in consumer behaviour is motivated by an emotional connection to the environment and not by factual knowledge of the impacts.

In short, understanding the purchase of secondhand products and its relationship with sustainable consumption is complex [66] but important for brands to develop or adjust their social responsibility and circular economy initiatives [67]. The determinants related to sustainable consumption play a decisive role in the purchase of secondhand products. Age, like other individual characteristics already studied [68,69,70], can influence the sustainable behaviour of consumers.

6. Conclusions

The results of this study reveal the intentions of consumers to make their habits more sustainable, specifically the intention to buy secondhand products.

TPB has been widely applied, but as far as is known, there are few studies of secondhand purchases that use TPB and that analyse the direct and indirect effects of the antecedent variables on attitude, subjective norm, PBC and the intention to purchase secondhand products. By using TPB and extending it to different variables, related to the sustainable consumption, the study adds value to the existing theory and contributes new results to management.

In this study, the relevant role of the three behavioural variables was confirmed: the strong influence of price, the need for exclusivity and frugality. Regarding environmental reasons, a greater influence of the emotional side (environmental concern) was confirmed, and the cognitive side (environmental knowledge) was denied.

The investigation also allowed us to evaluate the mediation effect of behavioural variables, highlighting the role of the attitude between price and purchase intention.

Finally, the research also contributes to the differentiation between the motivations of younger and older individuals. While for young people the environmental concern influences their intention to buy secondhand, in the case of older people this has no relevance. Many consumers are already highly aware of its impacts, but some are unaware of it. The communication of brands, relative to their sustainability should be one of their focuses in order to raise awareness and educate the consumer about the environmental benefits of changing their consumption. In this way, environmental factors may come to play a greater influence than economic issues, for example.

With the increase of information about changing habits along with the positive attitude towards sustainable consumption, such as secondhand shopping, will increase and consequently social pressure will influence individuals to perform such behaviours.

By understanding the motivations of individuals, brands can adapt strategies, implement initiatives and develop new products and services more tailored to the needs and interests of consumers.

Firms and brands must analyse and rethink their products/services in order to make their cycles more circular, from production to final disposal. Currently, there are several brands that have circularity initiatives implemented, from the sale of refurbished appliances to secondhand furniture. However, this market has to be easily accessible and comfortable for consumers. Creating online or physical spaces where used products can be easily found will reduce the possible barriers and fears that exist associated with the secondhand market. In this way, the behaviour becomes more noticeable to be executed and consequently, the role of the PBC will increase.

With these offers to sell, rent and/or exchange used products, brands can attract consumers who have an interest in sustainable products but who also have economic constraints. The secondhand market is a way to have a more sustainable consumption giving utility to goods that are still functional and avoiding the production of new ones.

Finally, looking at generational differences, we understand that younger people are more aware of the environmental situation, which ultimately influences their choices. Brands must emphasise their social responsibility to create a connection with young people as they will be the future consumers. In relation to the elderly, the economic side should be highlighted but an effort should be made to convey the environmental theme to them.

7. Limitations and Future Research

Although the present study evidences important contributions, it is important to identify some of its limitations that should be eliminated in future research.

First, for the convenience of data collection, the developed model evaluates the intention to purchase secondhand products and not the actual behaviour. There is a high correlation between the intention and the realisation of the action, that is, the stronger the intention to perform a certain behaviour, the greater the probability of it being realised [19]. Therefore, the results of the intention can give close indications of the realisation of the actual behaviour. Nevertheless, future studies may extend the model with the introduction of new variables and verify actual behaviour rather than intention.

In the extension of TPB we decided to focus on the factors of purchase intent in order to better recognise the motivations of consumers. In the future, it is suggested the introduction of risks/barriers that reduce the purchase intention in order to alert to their elimination.

The existing literature is quite limited to the fashion industry hindering the selection and introduction of different variables in the model. In this study and in order to broaden the knowledge, it does not focus on any specific product or a specific market, however, in future research it is suggested to focus on a type of product (furniture, technology, luxury products, etc.) or specific means of purchase (online, physical stores, etc.).

The sample analysed was diversified in sociodemographic terms, allowing for the multigroup analysis by age, although it presents the limitations of a convenience sample, and we cannot generalise the results. For future studies, a sample is suggested that allows for the generalisation of the results and that makes multigroup analyses based on other variables possible.