An Adaptation of the Quality–Loyalty Model to Study Green Consumer Loyalty

Abstract

This research proposes an adaptation of the quality–loyalty model in which affective commitment is integrated as a key factor in the proposed framework. The study presented a comprehensive framework encompassing 11 hypotheses formulated from an extensive literature review. Empirical data collected from 679 environmentally conscious consumers predominantly residing in Vietnam’s three principal urban centers were employed to evaluate these hypotheses. The assessment was executed utilizing the partial least squares structural equation modeling technique. The results of this research authenticate the appropriateness of the integrated model in studying green consumption, verify the critical role of affective commitment in the newly introduced model, and identify the high impact of affective commitment on green loyalty intention and green purchase behavior. This research also shows that other factors of the quality–loyalty model have significant influences on affective commitment and green loyalty intention. Moreover, this study signifies the crucial role of green perceived quality in fostering affective commitment and green loyalty intention. Green perceived quality was identified as a key factor influencing green loyalty intention and played a crucial role in encouraging customers to purchase environmentally friendly products.

1. Introduction

The global community is presently confronted with numerous critical challenges, including climate change, rising sea levels, and degradation of the natural environment. The majority of these dilemmas are attributable to humanity’s negligence regarding the ecological system. In reaction to these pressing concerns, individuals are modifying their interactions with the environment to adopt more sustainable practices. This has given rise to the phenomenon of green consumerism, which is directed towards environmentally sustainable practices and the preservation of the ecosystem. Green consumerism encompasses the procurement of environmentally friendly products, energy-efficient goods, and organic produce. According to Ritter, Borchardt [1], green products are defined as those items whose production and consumption contribute positively to environmental protection across various domains, including energy conservation, recycling, and the minimization of harmful waste. From an ecological perspective, green consumption holds the potential to facilitate the achievement of sustainable environmental development, thereby enhancing the sales and consumption of green products [2].

With the ascent of green consumerism in Vietnam and around the world, this research topic has garnered significant attention from both domestic and international scholars. Understanding green purchasing intentions and behaviors of consumers is also a key objective for marketers and policymakers, especially within emerging markets such as Vietnam. Vietnam is currently classified as an emerging market in Asia [3] and has experienced sustainable economic development in recent years [4]. The enhancement of living standards, coupled with heightened awareness of health and environmental issues in Vietnam, is driving green consumption.

To promote green consumption, companies are eager to sell more green products in their product portfolio and try to encourage customers to continue purchasing their green products [5]. In academic research, numerous researchers have examined why consumers purchase environmentally friendly products [6] and how to encourage customers to choose green products [7]. Others have focused on the elements that affect customers’ green purchasing behavior [8,9], particularly their loyalty to green purchases [10,11,12]. This research specifically targeted loyalty intention, which reflects a person’s inclination to stay engaged with or repeatedly buy from the same brand or product over a prolonged timeframe [13].

According to the literature, the quality–loyalty model [14] is largely regarded as a leading theory for analyzing loyalty intention within the service sector [12] and has also been applied to green consumption [15]. The Loyalty Chain Stage Theory [12], which is another important loyalty-related theory, shares many similarities with the quality–loyalty model; it suggests that perceived value and service quality (cognitive loyalty) affect satisfaction (affective loyalty), which in turn influences the intention to revisit (conative loyalty) and ultimately impacts behaviors (action loyalty). Green loyalty is often linked to the hospitality industry, retail sectors, etc., in the existing literature [12]. Various researchers have studied customers’ loyalty towards green products or product brands [15,16,17]. These studies highlighted that green perceived quality, green perceived value, and green satisfaction significantly enhance customers’ intention to remain loyal.

The quality–loyalty model and Loyalty Chain Stage Theory primarily focus on perceived quality, perceived value, satisfaction, and loyalty stages impacting loyalty intention. Rather, Tehseen [18] showed that satisfaction raised affective commitment, enhancing loyalty intention. In addition, affective commitment may also mediate the impacts of other factors of the quality–loyalty model on loyalty intention. This study, therefore, focuses on affective commitment, a type of commitment identified by Allen and Meyer [19] that has the potential to improve the productivity of loyalty intention. Affective commitment refers to the emotional bond or loyalty an individual has towards an organization, encompassing aspects of belonging, identification, and emotional investment. In marketing discussions, affective commitment suggests that customers wish to maintain their relationship because they value the partnership and feel a sense of loyalty [18]. Within the context of green consumption, affective commitment may signify a customer’s emotional connection to green products that bring them joy. A customer who feels an emotional tie to green products is likely to develop a favorable attitude towards them and demonstrate a stronger intention to purchase green products. Hence, this research integrates affective commitment into the quality–loyalty framework with the expectation of enhancing the explanatory power of the quality–loyalty framework in predicting both green loyalty intention and behavior.

This study addresses the gaps in the research on green loyalty by exploring the role of affective commitment influencing green loyalty intention and green purchase behavior, which has not been explicitly studied in the literature. The research also examines how service loyalty input factors (perceived quality, perceived value, and satisfaction) influenced green loyalty intention and how these factors influenced affective commitment in the integrated service loyalty framework.

The rest of the paper is organized as follows: Section 2 presents the paper’s conceptual framework, Section 3 describes the research methodology of the paper, Section 4 provides results and discussion, and the last section presents conclusions, limitations, and future research of the study.

2. Conceptual Framework

This research utilized the quality–loyalty model [14] as the core model to study loyalty intention with green products. This research focused mainly on green products with energy (saving) labels and product recycling labels for the survey. The quality–loyalty model reflects that perceived quality, perceived value, and satisfaction are the main predictors of loyalty intention. Other authors [20,21] indicate that commitment to products or services may enhance the variance explanation of loyalty intention. Therefore, this research integrates affective commitment into the quality–loyalty model for a better explanation of loyalty intention. In addition, customers with strong emotional commitment are more inclined to repurchase or keep using a product or service, even when there are similar alternatives available. This is comparable to the service sector, where employees who exhibit high levels of emotional commitment are more likely to remain with the organization and positively impact its success [18]. This means that affective commitment may influence purchase behavior; therefore, we include green purchase behavior in the newly proposed framework. The proposed model (Figure 1) has the potential to help us better understand the factors affecting consumer loyalty in green consumption and other environmentally related areas. The main frame for the model in Figure 1 is the quality–loyalty model [14], in which affective commitment is located at the center of the model to reflect the importance of this factor. In addition, purchase behavior is added in the proposed model to examine the impact of affective commitment and green loyalty intention on this factor.

2.1. Green Loyalty Intention and Green Purchase Behavior

Customer loyalty can be understood as a determination to repeatedly buy a product or utilize a service from a provider [22]. In practice, customer loyalty refers to a specific behavior exhibited by a customer toward a product or service that indicates their intention to continue using this offering from the organization. Generally, the willingness to repurchase or keep using the organization’s product or service [23,24] can be seen as a manifestation of loyalty intention. Achieving customer loyalty or the intention to repurchase is a vital objective for an organization [25], as it secures customers and generates profits over time [26].

Studies in the literature show that intention plays a pivotal role in shaping behavior [27], serving as a strong predictor of whether an individual will carry out a specific action. Rooted in motivational and cognitive processes, intention reflects a person’s readiness and commitment to perform a behavior. According to the Theory of Planned Behavior [27], a well-formed intention significantly increases the likelihood of the intended behavior occurring. Therefore, we propose the following hypothesis:

H1. 

Green loyalty intention significantly influences green purchase behavior.

2.2. Affective Commitment (to Green Products)

Commitment (organizational) can be studied from different angles [28], i.e., calculative, attitudinal, and multidimensional approaches. This research is interested in an attitudinal approach, with a focus on the affective aspect of commitment [20]. Affective commitment, characterized as a more emotionally charged element, emerges through personal engagement and mutual exchange between a consumer and an organization. This particular form of commitment results in an enhanced perception of trust and allegiance, as the consumer perceives themselves as emotionally invested in the brand or enterprise [18].

According to the literature, commitment is one of the most frequently studied variables used in buyer–seller relationship studies [29]. In previous studies, commitment has been used as a global construct (similar to attitude in consumer behavioral research) that measures the intention to continue the relationship [30]. Affective commitment, reflecting the emotional component of commitment, measures the feelings and emotional attachments customers may develop towards the firm providing the service [31]. Affective commitment means that customers want to stay in a relationship because they enjoy the partnership and feel a sense of loyalty [29]. This indicates the direct relationship between affective commitment and the loyalty (intention) of customers. Cater and Zabkar [30], in a discussion of the differences between commitment and loyalty, stated that commitment is predominantly cognitive and refers to the power of attitude and loyalty is a behavioral response that is a function of psychological processes. In green consumption research, customers do not tie in with the producers/manufacturers; therefore, affective commitment is the most prominent component that may show significant impacts on behavioral intention.

Studies in the literature have mainly focused on the commitment to maintaining the value relationships that are frequently found between customers and suppliers. The commitment can certainly extend to the relationship between customers and a particular type of product or brand (green product/brand in this case) that they feel they can get value from. Rather [29] argues that customers who demonstrate greater levels of commitment and who have developed robust relationships with a brand are likely to perceive strong associations with the brand. Other authors [29,30] also show that affective commitment has a significantly positive impact on customer loyalty.

The strong relationships between affective commitment, green loyalty intention, and green purchase behavior underscore the importance of emotional engagement in driving consumer behavior toward sustainability. Affective commitment plays a pivotal role in enhancing green loyalty intention and green purchase behavior by fostering strong emotional bonds between consumers and green products. This emotional attachment leads to sustained loyalty and promotes environmentally sustainable consumption behaviors. Therefore, we propose the following hypothesis:

H2a. 

Affective commitment (to green products) significantly influences green purchase behavior.

H2b. 

Affective commitment (to green products) significantly influences green loyalty intention.

2.3. Green Perceived Value

In a broad context, perceived value is conceptualized as the comprehensive evaluation of the value of a product by the consumer, which is contingent upon both the benefits received and the benefits offered. Woodruff [32] articulated that perceived value encapsulates the consumer’s interpretation of product characteristics, functional attributes, and the resultant impacts of usage in relation to the attainment of consumer objectives. According to Zeithaml [33], perceptions of value are influenced by the monetary amount expended on a product, the anticipations held by the consumer regarding that product, the quality attained in correlation with the price paid, and the comparative assessment of what consumers gain in relation to what they have contributed in the exchange. Perceived value fundamentally represents the advantages derived by a consumer from the acquisition of a product or service. An enhanced benefit is posited to correlate with an elevated degree of commitment, heightened satisfaction, and a diminished perception of risk.

Green perceived value also plays a crucial role in fostering customer loyalty. When consumers perceive that green products provide superior value, they are more likely to develop a positive emotional attachment to the brand, leading to affective commitment [34]. This emotional bond encourages repeat purchases and long-term loyalty to the brand. In addition, perceived value enhances customer satisfaction, which is a key determinant of loyalty. Satisfied customers are more likely to continue purchasing from the same brand and recommend it to others, thereby reinforcing their loyalty [31].

Additionally, the perceived value of green products can positively influence affective commitment, where consumers feel emotionally connected to the brand due to the environmental benefits provided. This connection further strengthens their loyalty and commitment to purchasing green products from the same brand in the future [1]. This discussion leads to the following hypotheses:

H3a. 

Green perceived value positively influences green loyalty intention.

H3b. 

Green perceived value positively influences affective commitment (to green products).

2.4. Green Satisfaction

Green satisfaction is the overall perception of customers regarding the performance and benefits of green products relative to their expectations. It encompasses both transactional satisfaction, which arises from the evaluation of a single purchase or usage experience, and cumulative satisfaction, which is based on the overall assessment of repeated usage over time [35]. Green satisfaction specifically focuses on how well green products meet the environmental and functional expectations of consumers, thereby contributing to their overall satisfaction with the product.

Numerous studies have demonstrated that higher levels of customer satisfaction lead to greater loyalty [14,17,36]. When consumers are satisfied with green products, they develop a positive attitude towards the brand, which translates into loyalty. Satisfied customers are more likely to exhibit repeat purchasing behavior, as they trust that the green products will consistently meet their needs and expectations. This loyalty is further reinforced by the alignment of the product’s environmental benefits with the consumer’s values [37].

Moreover, green satisfaction enhances affective commitment, which is the emotional attachment a customer feels toward a product or brand [31]. Affective commitment strengthens the loyalty of customers by fostering a deeper, emotional bond with the brand, making them less likely to switch to competitors. As customers become more emotionally invested in green products, their loyalty becomes more robust and enduring [30].

These arguments assume the relationship between green perceived satisfaction and the two factors of affective commitment and green loyalty intention:

H4a. 

Green satisfaction positively influences green loyalty intention.

H4b. 

Green satisfaction positively influences affective commitment (to green products).

2.5. Green Perceived Quality

Quality is usually defined as the degree to which a product or service satisfies customer requirements. Put another way, product quality is an expected standard of excellence in a product or service [38]. From a broader sense, product quality can be considered as a customer’s perception of all non-price attributes of an organization’s goods and services [39].

Product quality is a primary determinant of customer satisfaction [39]. When consumers perceive green products as high-quality, they are more likely to feel satisfied with their purchase. This satisfaction stems from the product meeting or exceeding their expectations in terms of both functional performance and environmental benefits. Satisfied customers are more likely to have positive experiences with green products, reinforcing their intention to continue purchasing these products in the future [40]. Practically, consumers who perceive green products as high-quality are likely to consider them as offering better value for the price paid as well. This perception of value is crucial for motivating purchase intentions and justifying any premium prices associated with green products [33].

Furthermore, affective commitment, or the emotional attachment a consumer feels towards a product, is also influenced by perceived quality. When consumers perceive green products as high-quality, they are more likely to develop a strong emotional bond with the product and the brand. This affective commitment enhances their loyalty and willingness to continue purchasing the product, as they feel a sense of trust and satisfaction with its performance and environmental impact [18].

Green perceived quality also positively impacts loyalty intention. When consumers believe that green products are of superior quality, they are more likely to remain loyal to the brand and continue purchasing these products. This loyalty is not only based on functional performance but also on the perceived environmental benefits that align with their values and beliefs about sustainability. Loyal customers are more likely to advocate for green products, recommending them to others and supporting the brand’s market position [38].

With these discussions, this paper assumes the following hypotheses:

H5a. 

Green product quality positively influences green loyalty intention.

H5b. 

Green product quality positively influences affective commitment.

H5c. 

Green product quality positively influences green perceived value.

H5d. 

Green product quality positively influences green satisfaction.

3. Methodology

3.1. Constructs and Measurement

The integrated framework in this research is mainly based on the quality–loyalty model, integrating affective commitment, which is a core component of the relationship marketing model. Constructs and indicators are derived from previous research. Indicators of constructs (or variables) are used and adopted from different studies: green satisfaction and green loyalty intention [15], green perceived value [41], green perceived quality [42], affective commitment [18], and green purchase behavior [42]. A five-point Likert scale ranging from 1 (“strongly disagree”) to 5 (“strongly agree”) was used to measure consumers’ opinions.

This investigation seeks to amass demographic data pertaining to consumers—obtained in the initial segment of the questionnaire—as well as to capture consumers’ perspectives regarding the research issue—collected in the subsequent segment of the questionnaire. A preliminary study involving 50 participants was conducted to validate the constructed questionnaire.

3.2. Sample and Data Collection

To gather consumer perspectives, we distributed questionnaires directly to prospective respondents at various locations, including shopping centers, media outlets, grocery stores, and similar venues. Furthermore, we employed Google Forms as an alternate medium for data acquisition. The volunteer sampling methodology [43] was applied to identify the prospective respondents. The participants in this inquiry have previously acquired green products on at least one occasion.

Saunders, Lewis [43] articulated that the volunteer sampling strategy, which is classified as a form of non-probability sampling, can yield more dependable samples in contrast to the frequently employed convenience sampling approach. Throughout the survey, we amassed a total of 679 completed questionnaires for subsequent data analysis. The data collection was conducted over a three-month timeframe (from May to July) in the year 2024.

The adequacy of the sample size in this study was substantiated through various statistical criteria: (a) the dataset must encompass a minimum of five times the number of indicators (given that the model comprises 18 indicators, a minimum of 90 observations is requisite), (b) to ensure an 80% statistical power and detect a minimum R² of 0.1 with a maximum of four paths leading to a green purchase intention construct at a significance level of 95%, a sample size of no less than 113 is essential [44]. In this particular instance, 679 observations were acquired and deemed suitable for analytical purposes.

4. Results and Discussion

4.1. Data Analysis

Table 1. Respondents’ characteristics.

Characteristic	Classification	Frequencies	Percentage (%)
Gender	Male	275	40.5%
	Female	400	58.9%
	Other	4	0.6%
Marital status	Married	422	62.2%
	Single	257	37.8%
Living area	Hanoi	225	33.1%
	HCM City	314	46.2%
	Da Nang	110	16.2%
	Other	30	4.4%
Education	K12	68	10.0%
	Colleague	111	16.3%
	Bachelor	340	50.1%
	Postgraduate	160	23.6%
Age	Under 23	133	19.6%
	23–under 30	173	25.5%
	30–under 45	281	41.4%
	45–under 60	83	12.2%
	60 and above	9	1.3%
Profession	Public servant	81	11.9%
	Entrepreneur	59	8.7%
	Manager/Departmental head	76	11.2%
	Officer/worker in a company	268	39.5%
	Free worker	51	7.5%
	Student	99	14.6%
	Other	45	6.6%
Monthly income (million VND)	Under 5	124	18.3%
	5–under 10	156	23.0%
	10–under 35	323	47.6%
	35–under 50	60	8.8%
	50 and above	16	2.4%
Total		679	100.0%

delineates the classification specifics of the study participants. The characteristics of the participants seem to be substantiated regarding gender, age, marital status, educational attainment, income level, and professional occupation and exhibit a substantial congruence with findings from prior scholarly investigations [45,46].

All indicators sourced from pre-existing scholarly works were employed, an exploratory factor analysis (EFA) was performed to evaluate the appropriateness and reliability of the factors and variables being investigated. According to Hair, Black [47], in general, a qualified factor needs to have a factor loading equal to 0.5 or higher. SmartPLS [44] was utilized to analyze the structural relationships posited by the proposed model. Additionally,

Table 2. Constructs and indicators of the model.

Construct and Indicators	EFA	PLS-SEM	Mean	Std	CA	CR	AVE
Green Perceived Quality					0.908	0.942	0.844
The quality of the green brand is high with respect to environmental concerns	0.908	0.909	3.962	0.705
The quality of the green brand is professional with respect to environmental reputation	0.719	0.918	3.959	0.659
The quality of the green brand is good with respect to environmental image	0.924	0.930	3.943	0.721
Affective Commitment					0.850	0.930	0.869
I am emotionally attached to the green product	0.784	0.931	3.960	0.702
I feel a strong sense of identification with the green product	0.716	Elemi-nated
The environmental friendliness of green products makes me feel good	0.828	0.933	3.990	0.674
Green Perceived Value					0.858	0.934	0.875
The green product’s environmental functions provide good value to me	0.939	0.934	3.971	0.671
The green product’s environmental performance meets my expectations	Eliminated
I purchase green products because it has more environmental benefits than non-green products	0.869	0.937	3.982	0.678
Green Satisfaction					0.900	0.937	0.833
You are glad about the decision to select the green product because of its environmental image	0.586	0.913	3.963	0.689
You think that it is the right decision to purchase the green product because of its environmental functionality	0.970	0.905	4.041	0.639
Overall, you are satisfied with the green product because of its environmental performance	0.763	0.920	3.993	0.668
Green Loyalty Intention					0.877	0.942	0.891
I am willing to repurchase the green product because of its (environmental) functions	0.903	Eliminated
I prefer purchasing the green product to other products because of its (environmental) performance	0.915	0.943	3.981	0.666
I intend to continue buying the green product because it is (environmentally) friendly	0.925	0.944	3.982	0.652
Green Purchase Behavior					0.857	0.933	0.875
I often buy a product or service from a brand that is environmentally friendly	0.653	Eliminated
When I have a choice between two brands, I often purchase the one less harmful to other people and the environment	0.837	0.933	4.050	0.643
I make a special effort to buy environmentally friendly products, e.g., products in biodegradable packages, energy-saving products, etc.	0.789	0.937	4.046	0.663

presents the reliability metrics (CA—Cronbach’s Alpha, CR—Composite Reliability, and AVE—Average Variance Extracted) pertinent to the model. Values for CA and CR exceeding 0.7, coupled with an AVE value surpassing 0.5, indicate that the reliability of the model is assured [44]. This research implemented the EFA procedure using Principal Component Analysis along with Promax with Kaiser Normalization for factor extraction.

After applying EFA, only one indicator of green perceived value was eliminated, and all factors were fed into the PLS-SEM model in SmartPLS4. This research applied an assessment procedure for the model with reflective constructs suggested by Hair, Hult [44]. Practicing assessment procedures, we eliminated a few indicators from several constructs in the model to guarantee the reliability criteria of the PLS-SEM model. All items were eliminated to satisfy the VIF and discriminant criterion of the proposed model.

The validity of the data’s discriminant aspects was confirmed through the implementation of the Fornell–Lacker criterion [48] and is illustrated in

Table 3. Discriminant validity (Fornell–Lacker).

	Affective Commitment	Green Loyalty Intention	Green Per. Qual	Green Per. Value	Green Purchase Behavior	Green Satisfaction
Affective Commitment	0.932
Green Loyalty Intention	0.767	0.944
Green Per. Quality	0.765	0.721	0.919
Green Per. Value	0.739	0.715	0.764	0.936
Green Purchase Behavior	0.729	0.665	0.696	0.748	0.935
Green Satisfaction	0.817	0.786	0.789	0.777	0.727	0.913

. The Fornell–Larcker criterion indicates that a diagonal value should be larger than all values in the same row and column. In this study, it was found that all variance inflation factors (VIFs) related to the latent variables were below the defined limit of 5 stated by Hair, Hult [44], indicating a lack of multicollinearity, as shown in

Table 4. Variance inflation factors (VIFs) and effect size f² of constructs in the model.

	AFC		GLI		GPV		GPB		GS		Q2
	f2	VIF	f2	VIF	f2	VIF	f2	VIF	f2	VIF
Affective Commitment (AFC)			0.074	3.503			0.264	2.429			0.614
Green Loyalty Intention (GLI)							0.062	2.429			0.600
Green Per. Quality (GPQ)	0.071	3.126	0.013	3.348	1.403	1.000			1.649	1.000	0.000
Green Per. Value (GPV)	0.033	2.978	0.021	3.076							0.506
Green Purchase Behavior (GPB)											0.483
Green Satisfaction (GS)	0.254	3.282	0.091	4.116							0.514

.

With regard to discriminant validity, the evaluation of common method bias (CMB) was performed by utilizing SPSS 22 and SmartPLS 4. An extensive analysis was conducted within the SmartPLS framework to verify the absence of multicollinearity, with careful examination of all variance inflation factor (VIF) values associated with both the inner and outer models. The results revealed that the highest VIF value for the inner constructs in this study was 4.116 (see Table 4), which is significantly below the critical threshold of 5 suggested by Hair, Black [47].

Hair, Hult [44] indicated that an f² value exceeding 0.2 signifies the presence of a substantial effect in the model—an effect that was observed in this study. Although the application of model fit in PLS-SEM is limited, the higher SRMR value of 0.076 for the estimated model, being under 0.09, indicates satisfactory results in this case [44]. The Q² values for the key variables (greater than 0) presented in Table 4 demonstrate that the PLS-SEM model possesses good predictive abilities.

The results of the bootstrapping procedure using SmartPLS4 are illustrated in Figure 2. The findings revealed a significant influence from all the variables; hence, all hypotheses were supported.

Figure 2 reveals that green perceived quality caused a significant direct effect on green loyalty intention, which is different from the results in the service field [14,49]. Moreover,

Table 5. Total impacts of factors in the model.

	Original Sample	Sample Mean	Standard Deviation	T Statistics	p Values
Affective Commitment -> Green Loyalty Intention	0.289	0.290	0.054	5.349	0.000
Affective Commitment -> Green Purchase Behavior	0.606	0.602	0.047	12.786	0.000
Green Loyalty Intention -> Green Purchase Behavior	0.257	0.260	0.067	3.819	0.000
Green Per. Quality -> Affective Commitment	0.765	0.764	0.027	28.528	0.000
Green Per. Quality -> Green Loyalty Intention	0.721	0.719	0.033	22.009	0.000
Green Per. Quality -> Green Per. Value	0.764	0.764	0.028	26.988	0.000
Green Per. Quality -> Green Purchase Behavior	0.592	0.591	0.039	15.133	0.000
Green Per. Quality -> Green Satisfaction	0.789	0.787	0.029	27.251	0.000
Green Per. Value -> Affective Commitment	0.167	0.167	0.049	3.423	0.001
Green Per. Value -> Green Loyalty Intention	0.192	0.194	0.054	3.529	0.000
Green Per. Value -> Green Purchase Behavior	0.138	0.140	0.034	4.093	0.000
Green Satisfaction -> Affective Commitment	0.488	0.487	0.053	9.160	0.000
Green Satisfaction -> Green Loyalty Intention	0.487	0.491	0.072	6.725	0.000
Green Satisfaction -> Green Purchase Behavior	0.385	0.384	0.040	9.706	0.000

Bold: most significant impact on green loyalty intention and green purchase behavior.

shows that this factor has the strongest effects on both affective commitment and green loyalty intention. The high R² values of the green loyalty intention (68.1%) and green purchase behavior (55.9%) constructs imply that the proposed model effectively explains these dependent variables.

4.2. Discussion

In the literature, several authors have studied the relationships between perceived service value, service satisfaction, and affective commitment [18,31] and the links between affective commitment and loyalty intention [18,20]. We have not found any study that posits affective commitment as central to the quality–loyalty model in the study of green consumption. Therefore, this research contributes to the literature on green consumption by introducing affective commitment, which is an important variable in the relationship marketing theory, into the quality–loyalty model to study green loyalty intention.

In this research, a green product is viewed as a tangible product including intangible characteristics such as the intangible experiences of customers with pro-environmental aspects. Green product perception, including the customer’s intangible experience, reflects a psychological factor that influences consumer emotions. Therefore, green product consumption research, to some extent, can be approached from the service perspective.

Green loyalty intention, which is the central dependent variable in this research, has been examined in the framework of integrating affective commitment into the quality–loyalty model. Our experimental results show that the integrated model is used appropriately to predict green loyalty intention (SRMR = 0.076). The high R² value (0.681) of green loyalty intention means that factors in the model can explain 68.1% variation of this variable, which is a high value. The R² value of the affective commitment variable is even higher (0.715). This means that the three factors of green perceived quality, perceived quality value, and green satisfaction contribute a large portion to explaining the affective commitment variable.

This research has a finding that is different from other studies in the service area [14,17,49], in which perceived service quality caused a negligible impact on loyalty intention. Green perceived quality in this case had a significant effect on green loyalty intention. Green perceived quality in this research is strongly related to feelings of intangible attributes related to the environmental aspects of green products that share some similarities with perceived service quality. Both are based on consumers’ individual experiences, beliefs, and expectations rather than purely objective measurements. From an emotional aspect, consumers often feel a moral or emotional connection to sustainable products and high-quality services, which influences purchasing decisions. Nonetheless, it seems that tangible aspects of green products play a significant role in this case. This is reflected by the significant direct impact of green perceived quality on green loyalty intention, which is similar to the results of Asshidin, Abidin [50].

In this research, green perceived quality has the highest effect on affective commitment and green loyalty intention. The influence of green loyalty quality on affective commitment can be explained by the idea that when consumers perceive a product/service as environmentally responsible, they may develop a stronger emotional attachment due to shared values. The strong impact of green perceived quality on other variables authenticates its important role in the pro-environmental research area and shows that green perceived quality is a key factor in promoting green consumption in practice. Figure 2 indicates that green perceived quality has a significant impact on other variables in the model (green perceived value, green satisfaction).

As indicated in the literature [18,20], affective commitment, characterized by an individual’s emotional attachment to environmental values, plays a crucial role in shaping green purchase intention and behavior. When consumers feel a deep emotional connection to green consumerism, they are more likely to choose eco-friendly products, remain loyal to green brands, and integrate environmental considerations into their purchasing decisions. This internal motivation fosters consistent, long-term green behavior and encourages the promotion of pro-environmental norms within social circles.

The experimental results (Figure 2) authenticate the important roles of affective commitment to green products in the quality–loyalty model. From an emotional perspective, when consumers feel emotionally connected to a green brand, they are more likely to develop long-term loyalty and repeat purchase behavior. This can explain the significant impact of affective commitment on green loyalty intention in our experiment. An individual who develops an affective commitment to a brand (or product) is likely to be loyal to this brand in the future [18,30].

The central role of affective commitment is assisted by strong links with the quality–loyalty model’s input factors, which are green perceived quality, green perceived value, and green satisfaction. Among these factors, green satisfaction has the highest impact (β = 0.488). Evidence indicates that when consumers are satisfied with a green product’s quality, performance, and ethical impact, they develop a stronger emotional bond with the brand [18,20,31,51]. The significant effect of green perceived value on affective commitment can be explained by the fact that consumers perceive a product or brand as truly valuable in terms of sustainability and so they develop a stronger emotional attachment to it [31,52].

Besides studying green loyalty intention, this research also focused on predicting green purchase behavior. The results in Table 5 signified that affective commitment is the most critical element in predicting green purchase behavior. Similar to the results from other authors, green loyalty intention had a positive effect on green purchase behavior (β = 0.289), but the intensity of the impact is much weaker than the influence of affective commitment (β = 0.522). Practically, when consumers develop an emotional attachment and a sense of identification with green products, they are more likely to consistently choose these products over conventional alternatives. This emotional bond strengthens their motivation to act in environmentally responsible ways, which translates into actual green purchasing behavior. Essentially, the stronger the affective commitment, the more likely consumers are to make sustainable buying choices.

4.3. Implications

The results authenticated the fitness of the proposed model (SRMR = 0.076 < 0.09), which was used to predict green loyalty intention. This model integrated affective commitment into the center of the service loyalty model and highlighted the important role of this factor in the study context.

We verify the crucial role of affective commitment in the integrated model, showing that it assists in further explaining the variation of green loyalty intention and green purchase behavior. This fills in a gap in the literature by demonstrating that affective commitment plays a vital role—beyond satisfaction—that links to the emotional bonds of customers, enhancing green loyalty intention and green purchase behavior in the pro-environmental consumption field.

This research also verified the key role of green perceived quality in influencing affective commitment and green loyalty intention. The strongest impacts of green perceived quality on affective commitment and green loyalty intention indicate that the root of green loyalty intention is green perceived quality. This means that to maintain the loyalty of customers to green products, the quality of green products (related to environmental aspects) is the first priority.

In addition to its theoretical significance, this study emphasized that customer experiences with green products (leading to perceived value and satisfaction), play a vital role in encouraging purchases of these products. This indicates that to effectively market green products and retain customer loyalty, businesses must create offerings that deliver value and leave customers feeling pleased or even thrilled with their eco-friendly choices. The value that consumers perceive is determined by their views on what they receive in comparison to what they provide; thus, improving the quality of green products must be accompanied by maintaining them at an affordable price.

5. Conclusions, Limitations, and Future Research

5.1. Conclusions

This research proposed an adaptation of the service loyalty model that included affective commitment at the center of the model to study green loyalty intention and green purchase behavior. This study verified the strong effects of green perceived quality. Green perceived value, green satisfaction, and affective commitment influence green loyalty intention; affective commitment played a key role. Moreover, affective commitment also exhibited an important role in green purchase behavior in this research context.

5.2. Limitations and Future Research

This study makes valuable contributions to the literature on green consumption. However, some limitations remain. First of all, we are interested in other attitudinal variables, such as attitude towards green products, and aim to incorporate such variables in the integrated model to observe the direct contribution and the interactions among these variables in another proposed framework.

Secondly, this research focused on the Vietnamese context. Vietnam is an emerging market [3] that has some specific cultural values that may have an impact on the research results that need to be explored further.

Thirdly, this research used the convenience (volunteer) sampling approach, which was another limitation. The limitations of volunteer sampling include self-selection bias, lack of generalizability, the overrepresentation of certain groups, motivation-related distortion, etc. To some extent, this limitation was reduced to a minimum, since we tried to evenly distribute participants by spreading data collection areas and sending questionnaires to a wide range of respondents.

Furthermore, the cross-sectional design of this research may limit the accuracy of the causality relationship between green loyalty intention (and even affective commitment) and green purchase behavior, since behavior lags behind intention.

In further research, we would like to study the interactions of attitude towards green products in the quality–loyalty framework and identify factors that motivate customers to purchase green products. Testing the stability of the model results based on longitudinal or cross-cultural studies is also interesting. Moreover, using a probability sampling method such as stratified sampling will help to enhance the validity and generalization capability of the research results.